阅读说明：本技术 液体喷出头和液体喷出设备 (Liquid ejection head and liquid ejection apparatus ) 是由 奥岛真吾 刈田诚一郎 青木孝纲 永井议靖 西谷英辅 驹宫友美 于 2017-01-06 设计创作，主要内容包括：提供液体喷出头和液体喷出设备。该液体喷出头包括：沿着第一方向的喷出口列；具有打印元件的压力室；与压力室连通的流路；供给口列,其沿着第一方向具有在第二方向上延伸且向流路供给液体的供给口；回收口列,其沿着第一方向具有在第二方向上延伸且从流路回收液体的回收口；沿着第一方向的第一共用供给流路,其用于向供给口列供给液体；沿着第一方向的第一共用回收流路,其用于从回收口列回收液体；在第二方向上延伸的第一供给侧连通口,其用于向第一共用供给流路供给液体；和在第二方向上延伸的第一回收侧连通口,其用于从第一共用回收流路回收液体,其中,第一供给侧连通口和第一回收侧连通口中的至少一者设置在多个位置。(A liquid ejection head and a liquid ejection apparatus are provided. The liquid ejection head includes: an ejection orifice row along a first direction; a pressure chamber having a printing element; a flow path communicating with the pressure chamber; a supply port row having supply ports extending in a second direction along the first direction and supplying liquid to the flow path; a recovery port row having a recovery port extending in the second direction along the first direction and recovering the liquid from the flow path; a first common supply flow path along a first direction for supplying liquid to the supply port row; a first common recovery flow path along the first direction for recovering the liquid from the recovery port row; a first supply-side communication port extending in the second direction for supplying the liquid to the first common supply flow path; and a first recovery-side communication port extending in the second direction for recovering the liquid from the first common recovery flow path, wherein at least one of the first supply-side communication port and the first recovery-side communication port is provided at a plurality of positions.)

1. A printing element substrate, comprising:

an ejection orifice array provided on one surface side and having a plurality of ejection orifices arranged in a first direction for ejecting a liquid;

a plurality of pressure chambers provided in correspondence with the ejection ports, each of the pressure chambers including an element for generating energy for ejecting liquid;

a supply port array in which a plurality of supply ports extending in a second direction and configured to supply a liquid to the pressure chamber are arranged in the first direction, wherein the liquid is ejected from the ejection port in the second direction;

a recovery port row in which a plurality of recovery ports are arranged in the first direction, the recovery ports extending in the second direction and configured to recover liquid from the pressure chambers;

a common supply flow path extending in the first direction and configured to supply liquid to the supply ports included in the supply port row;

a common recovery flow path extending in the first direction and configured to recover liquid from the recovery ports included in the recovery port row;

a supply-side communication port provided on the other surface side opposite to the one surface side for supplying a liquid to the common supply flow path; and

a recovery-side communication port provided on the other surface side for recovering the liquid from the common recovery flow path,

wherein at least one of the supply-side communication port and the recovery-side communication port is provided in number of two or more.

2. The printing element substrate according to claim 1,

when the printing element substrate is viewed from the other surface side, the supply-side communication port is smaller than the common supply flow path, and the recovery-side communication port is smaller than the common recovery flow path.

3. A printing element substrate according to claim 1, wherein each of the elements is a heating element.

4. The printing element substrate according to claim 1, wherein the other surface side is provided with a film member, and the supply-side communication port and the recovery-side communication port are formed in the film member.

5. The printing element substrate according to claim 4, wherein the film member contains a photosensitive resin material.

6. The printing element substrate according to claim 1, wherein a silicon member is provided on the other surface side, and the supply-side communication port and the recovery-side communication port are formed in the silicon member.

7. The printing element substrate according to claim 1, wherein the ejection orifices included in the ejection orifice array are arranged at a density of 600dpi or more.

8. A printing element substrate according to claim 1, wherein liquid circulates inside and outside the pressure chamber.

9. The printing element substrate according to claim 1, wherein the common supply flow path has a length corresponding to the ejection orifice array, and the common recovery flow path has a length corresponding to the ejection orifice array.

10. A printing element substrate according to claim 1, wherein the supply-side communication port and the recovery-side communication port are provided different in number.

11. A printing element substrate according to claim 1, wherein the supply-side communication port and the recovery-side communication port are provided to be the same in number.

12. A printing element substrate according to claim 1, wherein the supply port row and the supply-side communication port are provided at positions overlapping with the common supply flow path, and the recovery port row and the recovery-side communication port are provided at positions overlapping with the common recovery flow path, when the printing element substrate is viewed from the one surface side.

13. A printing element substrate according to claim 1, wherein said printing element substrate further comprises a plurality of ejection orifice arrays which eject different kinds of liquid.

14. A liquid ejection head, comprising:

a support member; and

a printing element substrate, the printing element substrate comprising:

an ejection orifice array provided on one surface side and having a plurality of ejection orifices arranged in a first direction for ejecting a liquid;

a plurality of pressure chambers provided in correspondence with the ejection ports, each of the pressure chambers including an element for generating energy for ejecting liquid;

a supply port array in which a plurality of supply ports extending in a second direction and configured to supply a liquid to the pressure chamber are arranged in the first direction, wherein the liquid is ejected from the ejection port in the second direction;

a recovery port row in which a plurality of recovery ports are arranged in the first direction, the recovery ports extending in the second direction and configured to recover liquid from the pressure chambers;

a common supply flow path extending in the first direction and configured to supply liquid to the supply ports included in the supply port row;

a common recovery flow path extending in the first direction and configured to recover liquid from the recovery ports included in the recovery port row;

a supply-side communication port provided on the other surface side opposite to the one surface side for supplying a liquid to the common supply flow path;

a recovery-side communication port provided on the other surface side for recovering liquid from the common recovery flow path, wherein the support member supports the printing element substrate, and

at least one of the supply-side communication port and the recovery-side communication port is provided in two or more in number.

15. A liquid ejection head according to claim 14, wherein the liquid ejection head is a page-wide liquid ejection head on which a plurality of the printing element substrates are arranged.

16. A liquid ejection head according to claim 15, wherein a plurality of the printing element substrates are arranged in a zigzag shape.

17. A liquid ejection head according to claim 15, wherein a plurality of the printing element substrates are linearly arranged.

18. A liquid ejection head according to claim 14, wherein the support member includes a second common supply flow path and a second common recovery flow path extending from one end side to the other end side of the support member, a plurality of independent supply flow paths extending from the second common supply flow path toward a central side in the lateral direction of the support member, and a plurality of independent recovery flow paths extending from the second common recovery flow path toward the central side.

19. A liquid ejection head according to claim 18, wherein the liquid ejection head includes a first pressure control unit that communicates with the second common supply flow path and a second pressure control unit that communicates with the second common recovery flow path, and a pressure value controlled by the first pressure control unit is larger than a pressure value controlled by the second pressure control unit.

20. A liquid ejection head according to claim 14, wherein liquid circulates inside and outside the pressure chamber.

21. A liquid ejection head according to claim 14, wherein each of the elements is a heating element.

22. A liquid ejection head according to claim 14, wherein a film member is provided on the other surface side, and the supply-side communication port and the recovery-side communication port are formed in the film member.

23. A liquid ejection head according to claim 22, wherein the film member contains a photosensitive resin material.

24. A liquid ejection head according to claim 14, wherein a silicon member is provided on the other surface side, and the supply-side communication port and the recovery-side communication port are formed in the silicon member.

Technical Field

The present invention relates to a liquid ejection head and a liquid ejection apparatus capable of ejecting liquid such as ink from ejection orifices.

Background

In the ink jet technology for printing an image by ejecting liquid such as ink, demands for high precision and high quality printing operation are increasing according to various application fields of recent ink jet printing operation. In order to improve the accuracy of the printing operation, a method of improving the printing resolution by densely arranging a plurality of ejection ports is known. Further, in order to realize a high-quality printing operation, it is necessary to suppress thickening of ink due to evaporation of water in the ejection orifice, because the thickened ink causes a decrease in the ejection speed of droplets or modulation of color density.

As a method of suppressing thickening of ink due to evaporation of water in the ejection orifice, the following methods are known: ink in a pressure chamber in which an ejection port is arranged is forcibly flowed, so that thickened ink staying in the pressure chamber flows to the outside. However, when the circulation flow rate of the ink flowing in each pressure chamber is not uniform or the pressure in each pressure chamber is not uniform, there arises a problem that the difference in ejection characteristics or color density between the ejection orifices is increased. In order to solve this problem, japanese patent laid-open No. 2009-179049 discloses the following method: the flow path resistance of the pressure chamber is kept at 1/100 or less of the flow path resistance of the flow path for supplying ink to the pressure chamber and the flow path resistance of the flow path for recovering ink from the pressure chamber.

However, in order to arrange a plurality of ejection orifices densely, when the number of ejection orifices constituting the ejection orifice array is increased or the interval between the ejection orifice arrays is narrowed, a problem in japanese patent laid-open No. 2009-179049 is found. That is, it is found that it is not easy to suppress a change in the circulation flow rate of the ink flowing in each pressure chamber or a change in the pressure of each pressure chamber. When the number of the ejection orifices constituting the ejection orifice array is increased, the distribution of the ejection orifices in the array direction (array extending direction) of the ejection orifice array becomes wider. Therefore, a change in the circulation flow rate of ink flowing through each pressure chamber or a change in the pressure of each pressure chamber is likely to occur between the plurality of pressure chambers arranged in the row direction of the ejection orifice row. Further, when a plurality of ejection orifice arrays are arranged at high density, it is difficult to increase the width of the flow path extending in the array direction of the ejection orifice arrays (the length in the arrangement direction of the plurality of ejection orifice arrays) due to the relationship between the adjacent flow paths. For this reason, a large pressure loss occurs. As a result, there are cases where: a change in the circulation flow rate of ink flowing in each pressure chamber or a change in the pressure of each pressure chamber occurs between the plurality of pressure chambers arranged in the row direction of the ejection orifice row.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to suppress a pressure change or a circulation flow rate change of a liquid flowing through a flow path of a liquid ejection head in which a plurality of ejection orifices are densely arranged.

According to a first aspect of the present invention, there is provided a liquid ejection head comprising: an ejection orifice array in which a plurality of ejection orifices configured to eject a liquid are arranged in a first direction; a pressure chamber configured with a printing element configured to generate energy for ejecting liquid; a flow path communicating with the pressure chamber; a supply port array in which a plurality of supply ports extending in a second direction intersecting a surface on which the printing elements are provided and configured to supply liquid to the flow path are arranged in the first direction; a recovery port row in which a plurality of recovery ports extending in the second direction and configured to recover liquid from the flow path are arranged in the first direction; a first common supply flow path extending in the first direction and configured to supply liquid to the supply port row; a first common recovery flow path extending in the first direction and configured to recover liquid from the recovery port row; a first supply-side communication port that extends in the second direction and is configured to supply liquid to the first common supply flow path; and a first recovery-side communication port extending in the second direction and configured to recover liquid from the first common recovery flow path, wherein at least one of the first supply-side communication port and the first recovery-side communication port is provided at a plurality of positions.

According to a second aspect of the present invention, there is provided a liquid ejection apparatus including: a liquid ejection head comprising: an ejection orifice array in which a plurality of ejection orifices configured to eject a liquid are arranged in a first direction; a pressure chamber configured with a printing element configured to generate energy for ejecting liquid; a flow path communicating with the pressure chamber; a supply port array in which a plurality of supply ports extending in a second direction intersecting a surface on which the printing elements are provided and configured to supply liquid to the flow path are arranged in the first direction; a recovery port row in which a plurality of recovery ports extending in the second direction and configured to recover liquid from the flow path are arranged in the first direction; a first common supply flow path extending in the first direction and configured to supply liquid to the supply port row; a first common recovery flow path extending in the first direction and configured to recover liquid from the recovery port row; a first supply-side communication port that extends in the second direction and is configured to supply liquid to the first common supply flow path; and a first recovery-side communication port extending in the second direction and configured to recover liquid from the first common recovery flow path, wherein at least one of the first supply-side communication port and the first recovery-side communication port is provided at a plurality of positions; and a supply unit configured to supply liquid to the first supply-side communication port, the first common supply flow path, the pressure chamber, the first common recovery flow path, and the first recovery-side communication port in this order.

According to a third aspect of the present invention, there is provided a liquid ejection head including an ejection orifice configured to eject a liquid, the liquid ejection head including: a first substrate including a pressure chamber having a plurality of printing elements configured to generate energy for ejecting liquid, a plurality of supply ports serving as through holes configured to supply liquid to the pressure chamber, and a plurality of recovery ports serving as through holes configured to recover liquid from the pressure chamber; a second substrate including a first common supply flow path that communicates with the plurality of supply ports and extends in a direction along a surface of the first substrate on which printing elements are provided, and a first common recovery flow path that communicates with the plurality of recovery ports and extends in the direction; and a cover member including a first supply-side communication port serving as a through-hole configured to supply liquid to the first common supply flow path and a first recovery-side communication port serving as a through-hole configured to recover liquid from the first common recovery flow path, wherein at least one of the first supply-side communication port and the first recovery-side communication port is provided at a plurality of positions.

According to a fourth aspect of the present invention, there is provided a liquid ejection head including an ejection orifice configured to eject a liquid, the liquid ejection head including: a printing element substrate including a pressure chamber having a plurality of printing elements configured to generate energy for ejecting liquid, a plurality of supply ports serving as through holes configured to supply liquid to the pressure chamber, a plurality of recovery ports serving as through holes configured to recover liquid from the pressure chamber, a first common supply flow path communicating with the plurality of supply ports and extending in a direction along a face on which the printing elements are provided, and a first common recovery flow path communicating with the plurality of recovery ports and extending in the direction; and a cover member including a first supply-side communication port serving as a through-hole configured to supply liquid to the first common supply flow path and a first recovery-side communication port serving as a through-hole configured to recover liquid from the first common recovery flow path, wherein at least one of the first supply-side communication port and the first recovery-side communication port is provided at a plurality of positions.

According to the present invention, it is possible to suppress a change in the circulation flow rate and a change in the pressure of the liquid flowing through the liquid ejection head.

Other features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the accompanying drawings).

Drawings

Fig. 1 is a diagram showing a schematic configuration of a liquid ejection apparatus that ejects a liquid;

fig. 2 is a schematic diagram showing a first circulation pattern among circulation paths suitable for the printing apparatus;

FIG. 3 is a schematic diagram showing a second circulation pattern among circulation paths suitable for the printing apparatus;

fig. 4 is a schematic diagram showing a difference in ink inflow amount to the liquid ejection head;

fig. 5A is a perspective view illustrating a liquid ejection head;

fig. 5B is a perspective view showing the liquid ejection head;

fig. 6 is an exploded perspective view showing component parts or units constituting the liquid ejection head;

fig. 7 is a view showing front and back surfaces of the first to third flow path members;

fig. 8 is a perspective view showing a portion α of fig. 7 (a) when viewed from the ejection module mounting surface;

FIG. 9 is a sectional view taken along line IX-IX of FIG. 8;

fig. 10A is a perspective view showing one ejection module;

FIG. 10B is an exploded view showing one ejection module;

fig. 11A is a diagram illustrating a printing element substrate;

fig. 11B is a diagram illustrating a printing element substrate;

fig. 11C is a diagram illustrating a printing element substrate;

fig. 12 is a perspective view showing a cross section of the printing element substrate and the cover member;

fig. 13 is a partially enlarged top view of an adjacent portion of the printing element substrate;

fig. 14A is a perspective view showing a liquid ejection head;

fig. 14B is a perspective view showing the liquid ejection head;

fig. 15 is an oblique exploded view showing the liquid ejection head;

fig. 16 is a diagram showing a first flow path member;

fig. 17 is a perspective view showing a liquid connection relationship between the printing element substrate and the flow path member;

FIG. 18 is a cross-sectional view taken along line XVIII-XVIII of FIG. 17;

fig. 19A is a perspective view showing one ejection module;

FIG. 19B is an exploded view showing one ejection module;

fig. 20 is a schematic view showing a printing element substrate;

fig. 21 is a diagram illustrating an inkjet printing apparatus that prints an image by ejecting liquid;

fig. 22A to 22M are exploded views showing main portions of a liquid ejection head according to a first embodiment of the present invention;

fig. 23A to 23G are exploded views showing a part of a liquid ejection head according to a first embodiment;

fig. 24A and 24B are sectional views showing a part of a liquid ejection head according to the first embodiment;

fig. 25 is an equivalent circuit diagram showing a part of a liquid ejection head according to the first embodiment;

fig. 26A is an equivalent circuit diagram showing a part of a liquid ejection head according to the first embodiment;

fig. 26B is a diagram showing a pressure distribution within a flow path of the liquid ejection head according to the first embodiment;

fig. 27 is a plan view showing a printing element substrate according to the first embodiment;

fig. 28A to 28C are top perspective views illustrating a part of a liquid ejection head according to the first embodiment;

fig. 29A to 29M are exploded views showing main portions of a liquid ejection head according to a second embodiment of the present invention;

fig. 30 is a plan view showing a printing element substrate according to the second embodiment;

fig. 31 is a top perspective view showing a part of a liquid ejection head according to a second embodiment;

fig. 32A to 32D are diagrams showing changes in the circulation flow rate according to the second embodiment;

fig. 33A to 33L are exploded views showing a liquid ejection head according to a third embodiment of the present invention;

fig. 34A to 34M are exploded views showing a liquid ejection head according to a fourth embodiment of the present invention;

fig. 35A to 35E are overall views showing a liquid ejection head of the present invention;

fig. 36 is a conceptual diagram showing an example of the ink supply system of the present invention;

fig. 37 is a graph showing the influence of the flow rate variation of the ink circulation flow;

fig. 38 is a view showing an example of a manufacturing step of the liquid ejection head of the present invention; and

fig. 39A to 39D are diagrams illustrating temperature distributions of the printing element substrate according to the second embodiment.

Fig. 40 is a schematic explanatory diagram showing a liquid ejection apparatus according to a first application example;

fig. 41 is an explanatory diagram showing a third cycle mode;

fig. 42A and 42B are explanatory views showing a liquid ejection head of a first application example;

fig. 43 is an explanatory view showing a liquid ejection head of the first application example;

fig. 44 is an explanatory view showing a liquid ejection head of a first application example;

fig. 45 is a schematic explanatory view showing a liquid ejection apparatus according to a third application example;

fig. 46 is an explanatory diagram showing a fourth cycle mode;

fig. 47A and 47B are explanatory views each showing a liquid ejection head according to a third application example; and fig. 48A, 48B, and 48C are explanatory views each showing a liquid ejection head according to a third application example.

Detailed Description

Hereinafter, a liquid ejection head and a liquid ejection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

In addition, the liquid ejection head and the liquid ejection apparatus of the present invention can be suitably used for printers, copiers, facsimile machines having a communication system, and word processors having a printer, and industrial printing apparatuses combined with various processing devices. For example, the liquid ejection head and the liquid ejection apparatus can be used for manufacturing biochips (biochips) or printing circuits.

Further, since application examples and embodiments to be described below are specific examples of the present invention, various technical limitations can be imposed on the examples of the present invention. However, the embodiments are not limited to the embodiments of the present specification or other detailed methods, and can be modified within the gist of the present invention.

Hereinafter, suitable application examples of the present invention will be explained.

(first application example)

(Explanation of ink jet printing apparatus)

Fig. 1 is a diagram showing a schematic configuration of a liquid ejection apparatus that ejects a liquid in the present invention, particularly, an inkjet printing apparatus (hereinafter, also referred to as a printing apparatus) 1000 that prints an image by ejecting ink. The printing apparatus 1000 includes: a conveying unit 1 for conveying a printing medium 2; and a line-type (page width type) liquid ejection head 3 arranged substantially orthogonal to the conveyance direction of the printing medium 2. Then, the printing apparatus 1000 is a line printing apparatus as follows: the printing apparatus continuously prints images in one pass by ejecting ink onto the relatively moving printing medium 2 while continuously or intermittently conveying the printing medium 2. The liquid ejection head 3 includes: a negative pressure control unit 230 that controls the pressure (negative pressure) in the circulation path; a liquid supply unit 220 that communicates with the negative pressure control unit 230 so that fluid can flow between the liquid supply unit 220 and the negative pressure control unit 230; a liquid connection portion 111 serving as an ink supply port and an ink discharge port of the liquid supply unit 220; and a housing 80. The printing medium 2 is not limited to cut paper, but may be a continuous roll medium (rolmedium).

The liquid ejection head 3 is capable of printing a full-color image by inks of cyan C, magenta M, yellow Y, and black K, and the liquid ejection head 3 is fluidly connected to a liquid supply member, a main tank, and a buffer tank (refer to fig. 2 described later) as a supply path that supplies liquid to the liquid ejection head 3. Further, a control unit that supplies electric power and sends an ejection control signal to the liquid ejection head 3 is electrically connected to the liquid ejection head 3. The liquid path and the electric signal path in the liquid ejection head 3 will be described later.

The printing apparatus 1000 is an inkjet printing apparatus that circulates liquid such as ink between a liquid tank and a liquid ejection head 3 described later. The circulation mode includes: a first circulation mode in which the liquid is circulated by driving two circulation pumps (for high pressure and low pressure) at the downstream side of the liquid ejection head 3; and a second circulation mode in which the liquid is circulated by driving two circulation pumps (for high pressure and low pressure) on the upstream side of the liquid ejection head 3. Hereinafter, the first and second circulation patterns of the circulation will be explained.

(description of the first circulation mode)

Fig. 2 is a schematic diagram showing a first circulation pattern among circulation paths of the printing apparatus 1000 suitable for the present application example. The liquid ejection head 3 is fluidly connected to a first circulation pump (high pressure side) 1001, a first circulation pump (low pressure side) 1002, and a buffer reservoir 1003. In fig. 2, for the sake of simplifying the description, a path through which ink of one color of cyan C, magenta M, yellow Y, and black K flows is shown. However, in reality, circulation paths of four colors are provided in the liquid ejection head 3 and the printing apparatus main body.

In the first circulation mode, the ink in the main tank 1006 is supplied to the buffer tank 1003 by the replenishment pump 1005, and then supplied to the liquid supply unit 220 of the liquid ejection head 3 via the liquid connection portion 111 by the second circulation pump 1004. Subsequently, the ink adjusted to two different negative pressures (high pressure and low pressure) by the negative pressure control unit 230 connected to the liquid supply unit 220 is circulated while being divided into two flow paths having high pressure and low pressure, respectively. The ink inside the liquid ejection head 3 is circulated in the liquid ejection head by the action of a first circulation pump (high pressure side) 1001 and a first circulation pump (low pressure side) 1002 on the downstream side of the liquid ejection head 3, the ink is discharged from the liquid ejection head 3 through the liquid connection portion 111, and the ink is returned to the buffer tank 1003.

The buffer tank 1003 as a sub tank is connected to the main tank 1006 and includes an atmospheric communication port (not shown) that communicates the inside and outside of the tank, and thus can discharge bubbles in the ink to the outside. A makeup pump 1005 is provided between the buffer tank 1003 and the main tank 1006. After ink is consumed by ejecting (discharging) ink from the ejection orifices of the liquid ejection head 3 in the printing operation and the suction recovery operation, the replenishment pump 1005 sends the ink from the main tank 1006 to the buffer tank 1003.

The two first circulation pumps 1001 and 1002 suck out the liquid from the liquid connection portion 111 of the liquid ejection head 3 so that the liquid flows toward the buffer reservoir 1003. As the first circulation pump, a volumetric pump having a quantitative liquid conveying capacity is desired. Specifically, a tube pump, a gear pump, a diaphragm pump, and a syringe pump can be exemplified. However, for example, a general constant flow valve or a general safety valve may be provided at the outlet of the pump to ensure a predetermined flow rate. When the liquid ejection head 3 is driven, the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 operate so that ink flows through the common supply flow path 211 and the common recovery flow path 212 at predetermined flow rates. Since the ink flows in this manner, the temperature of the liquid ejection head 3 during the printing operation is maintained at the optimum temperature. The predetermined flow rate when the liquid ejection head 3 is driven is desirably set to be equal to or higher than the flow rate when the temperature difference between the printing element substrates 10 within the liquid ejection head 3 does not affect the printing quality. In particular, when an excessively high flow rate is set, the negative pressure difference between the printing element substrates 10 increases due to the influence of pressure loss of the flow path in the liquid ejection unit 300, and thus density unevenness in an image is caused. For this reason, it is desirable to set the flow rate in consideration of the temperature difference and the negative pressure difference between the printing element substrates 10.

The negative pressure control unit 230 is disposed in a path between the second circulation pump 1004 and the liquid ejection unit 300. The negative pressure control unit 230 is operated to be able to keep the pressure on the downstream side of the negative pressure control unit 230 (i.e., the pressure in the vicinity of the liquid ejection unit 300) at a predetermined pressure even in the case where the flow rate of ink in the circulation system varies due to a difference in ejection amount per unit area. As the two negative pressure control mechanisms constituting the negative pressure control unit 230, any mechanism may be used as long as the pressure on the downstream side of the negative pressure control unit 230 can be controlled within a predetermined range centered on a desired set pressure.

As an example, a mechanism such as a so-called "pressure reducing regulator" or the like can be employed. In the circulation flow path of the present application example, the upstream side of the negative pressure control unit 230 is pressurized by the second circulation pump 1004 via the liquid supply unit 220. With this configuration, since the influence of the water head pressure of the buffer tank 1003 with respect to the liquid ejection head 3 can be suppressed, the degree of freedom in layout of the buffer tank 1003 of the printing apparatus 1000 can be expanded.

As the second circulation pump 1004, a turbo pump or a displacement pump can be used as long as a predetermined head pressure (head pressure) or more can be exhibited in a range of the ink circulation flow rate used when the liquid ejection head 3 is driven. In particular, a diaphragm pump may be used. Further, for example, a water head reservoir configured to have a certain water head difference with respect to the negative pressure control unit 230 can be used instead of the second circulation pump 1004. As shown in fig. 2, the negative pressure control unit 230 includes two negative pressure adjustment mechanisms having different control pressures, respectively. In the two negative pressure adjustment mechanisms, a relatively high pressure side (indicated by "H" in fig. 2) and a relatively low pressure side (indicated by "L" in fig. 2) are connected to the common supply flow path 211 and the common recovery flow path 212 in the liquid ejection unit 300, respectively, by the liquid supply unit 220.

The liquid discharge unit 300 is provided with a common supply channel 211, a common recovery channel 212, and an independent channel 215 (an independent supply channel 213 and an independent recovery channel 214) that communicate with the printing element substrate. The negative pressure control mechanism H is connected to the common supply flow path 211, the negative pressure control mechanism L is connected to the common recovery flow path 212, and a pressure difference is formed between the two common flow paths. Then, since the independent channel 215 communicates with the common supply channel 211 and the common collection channel 212, the following flows (flows indicated by arrow directions in fig. 2) are generated: a part of the liquid flows from the common supply channel 211 to the common recovery channel 212 through the channels formed in the printing element substrate 10.

In this way, the liquid ejection unit 300 has the following flows: a part of the liquid flows through the printing substrate 10 while flowing through the common supply flow path 211 and the common recovery flow path 212. For this reason, heat generated by the printing element substrate 10 can be discharged to the outside of the printing element substrate 10 by ink flowing through the common supply flow path 211 and the common recovery flow path 212. With this configuration, even in a case where the pressure chamber or the ejection port does not eject the liquid when an image is printed by the liquid ejection head 3, the ink flow can be generated. Therefore, the thickening of the ink can be suppressed so as to reduce the viscosity of the ink thickened in the ejection port. Further, the thickened ink or foreign matter in the ink can be discharged toward the common recovery flow path 212. Therefore, the liquid ejection port 3 of the present application example can print a high-quality image at high speed.

(description of second circulation mode)

Fig. 3 is a schematic diagram showing a second circulation pattern which is a circulation pattern different from the first circulation pattern in the circulation path of the printing apparatus applied to the present application example. The main difference from the first circulation mode is that both the two negative pressure control mechanisms constituting the negative pressure control unit 230 control the pressure on the upstream side of the negative pressure control unit 230 within a predetermined range centered on a desired set pressure. Further, another difference from the first cycle mode is that: the second circulation pump 1004 serves as a negative pressure source for reducing the pressure on the downstream side of the negative pressure control unit 230. Further, still another difference from the first circulation mode is that a first circulation pump (high pressure side) 1001 and a first circulation pump (low pressure side) 1002 are disposed on the upstream side of the liquid ejection head 3, and the negative pressure control unit 230 is disposed on the downstream side of the liquid ejection head 3.

In the second circulation mode, the ink in the main tank 1006 is supplied to the buffer tank 1003 by the replenishment pump 1005. Subsequently, the ink is divided into two flow paths and circulated in the two flow paths on the high pressure side and the low pressure side by the action of the negative pressure control unit 230 provided to the liquid ejection head 3. The ink divided into two flow paths on the high pressure side and the low pressure side is supplied to the liquid ejection head 3 through the liquid connection portion 111 by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002. Subsequently, the ink circulated inside the liquid ejection head by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 is discharged from the liquid ejection head 3 via the liquid connection portion 111 by the negative pressure control unit 230. The discharged ink is returned to the buffer tank 1003 by the second circulation pump 1004.

In the second circulation mode, even when the flow rate changes due to a change in the ejection amount per unit area, the negative pressure control unit 230 can stabilize the change in the pressure on the upstream side of the negative pressure control unit 230 (i.e., the liquid ejection unit 300) within a predetermined range centered on a predetermined pressure. In the circulation flow path of the present application example, the downstream side of the negative pressure control unit 230 is pressurized by the second circulation pump 1004 via the liquid supply unit 220. With this configuration, since the influence of the head pressure of the buffer tank 1003 with respect to the liquid ejection head 3 can be suppressed, the layout of the buffer tank 1003 in the printing apparatus 1000 can be made to have many choices.

For example, instead of the second circulation pump 1004, it is also possible to use a water head reservoir configured to have a predetermined water head difference with respect to the negative pressure control unit 230. In the second circulation mode, the negative pressure control unit 230 includes negative pressure control mechanisms having different control pressures, respectively, as in the first circulation mode. In the two negative pressure adjustment mechanisms, a high pressure side (indicated by "H" in fig. 3) and a low pressure side (indicated by "L" in fig. 3) are connected to the common supply flow path 211 or the common recovery flow path 212 in the liquid ejection unit 300, respectively, by the liquid supply unit 220. When the pressure of the common supply channel 211 is set higher than the pressure of the common recovery channel 212 by the two negative pressure adjustment mechanisms, a liquid flow from the common supply channel 211 to the common recovery channel 212 through the independent channels 215 and the channels in the printing element substrate 10 is formed.

In such a second circulation mode, the same liquid flow as in the first circulation mode can be obtained in the liquid ejection unit 300, but there are two advantages different from the first circulation mode. As a first advantage, in the second circulation mode, since the negative pressure control unit 230 is disposed on the downstream side of the liquid ejection head 3, there is little fear that foreign matters or waste generated by the negative pressure control unit 230 flow into the liquid ejection head 3. As a second advantage, in the second circulation mode, the maximum value of the flow rate required for the liquid to flow from the buffer reservoir 1003 to the liquid ejection head 3 is smaller than that in the first circulation mode. The reason is as follows.

In the case of circulation in the print standby state, the sum of the flow rates of the common supply flow path 211 and the common recovery flow path 212 is set to the flow rate a. The value of the flow rate a is defined as a minimum flow rate required to adjust the temperature of the liquid ejection head 3 in the printing standby state so that the temperature difference within the liquid ejection unit 300 falls within a desired range. Further, an ejection flow rate obtained in a case where ink is ejected from all the ejection orifices of the liquid ejection unit 300 (a full ejection state) is defined as a flow rate F (ejection amount per ejection orifice × ejection frequency per unit time × number of ejection orifices).

Fig. 4 is a schematic diagram showing a difference in ink inflow amount of the liquid ejection head 3 between the first circulation mode and the second circulation mode. Fig. 4 (a) shows a standby state in the first circulation mode, and fig. 4 (b) shows a full ejection state in the first circulation mode. Fig. 4 (c) to 4 (f) show the second cycle mode. Here, (c) of fig. 4 and (d) of fig. 4 show the case where the flow rate F is lower than the flow rate a, and (e) of fig. 4 and (F) of fig. 4 show the case where the flow rate F is higher than the flow rate a. In this way, the flow rates in the standby state and the full ejection state are shown.

In the case of the first circulation mode in which the first circulation pump 1001 and the first circulation pump 1002 each having a fixed-amount liquid conveying capacity are disposed on the downstream side of the liquid ejection head 3 (fig. 4 (a) and 4 (b)), the total flow rate of the first circulation pump 1001 and the first circulation pump 1002 is set to the flow rate a. The flow rate a allows the temperature in the liquid discharge unit 300 to be controlled in the standby state. Thus, in the case of the full discharge state of the liquid discharge head 3, the total flow rate of the first circulation pump 1001 and the first circulation pump 1002 is maintained at the flow rate a. However, due to the action of the negative pressure generated by the ejection of the liquid ejection head 3, the maximum flow rate of the liquid supplied to the liquid ejection head 3 is obtained by adding the flow rate F consumed by the full ejection to the flow rate a of the total flow rate. Thus, the maximum value of the supply amount to the liquid ejection head 3 satisfies the relationship of the flow rate a + the flow rate F by adding the flow rate F to the flow rate a ((b) of fig. 4).

Meanwhile, in the case of the second circulation mode in which the first circulation pump 1001 and the first circulation pump 1002 are disposed on the upstream side of the liquid ejection head 3 (fig. 4 (c) to 4 (f)), the supply amount required for the liquid ejection head 3 in the print standby state is the flow rate a, as in the first circulation mode. Therefore, in the case where the flow rate a is higher than the flow rate F in the second circulation mode in which the first circulation pump 1001 and the first circulation pump 1002 are disposed on the upstream side of the liquid ejection head 3 (fig. 4 (c) and 4 (d)), the flow rate a as the supply amount to the liquid ejection head 3 is sufficient even in the full ejection state. At this time, the discharge flow rate of the liquid ejection head 3 satisfies the relationship of flow rate a-flow rate F ((d) of fig. 4).

However, in the case where the flow rate F is higher than the flow rate a ((e) of fig. 4 and (F) of fig. 4), in the case where the flow rate of the liquid supplied to the liquid ejection head 3 is set to the flow rate a in the full ejection state, the flow rate becomes insufficient. For this reason, when the flow rate F is higher than the flow rate a, the supply amount to the liquid ejection head 3 needs to be set to the flow rate F. At this time, since the flow rate F is consumed by the liquid ejection head 3 in the full ejection state, the flow rate of the liquid discharged from the liquid ejection head 3 is almost zero ((F) of fig. 4). Further, if the liquid is ejected in the non-full ejection state in the case where the flow rate F is higher than the flow rate a, the liquid absorbed by the amount consumed by the ejection of the flow rate F is discharged from the liquid ejection head 3. Further, in the case where the flow rate a and the flow rate F are equal to each other, the flow rate a (or the flow rate F) is supplied to the liquid ejection head 3, and the flow rate F is consumed by the liquid ejection head 3. For this reason, the flow rate discharged from the liquid ejection head 3 becomes almost zero.

In this way, in the case of the second circulation mode, the total value of the flow rates set for first circulation pump 1001 and first circulation pump 1002, that is, the maximum value of the required supply flow rate becomes the larger value of flow rate a and flow rate F. For this reason, as long as the liquid ejection units 300 having the same configuration are used, the maximum value of the supply amount (flow rate a or flow rate F) required for the second circulation mode becomes smaller than the maximum value of the supply amount (flow rate a + flow rate F) required for the first circulation mode.

For this reason, in the case of the second circulation mode, the degree of freedom of the applicable circulation pump is increased. For example, a circulation pump having a simple configuration and low cost can be used or the load of a cooler (not shown) provided in the main body side path can be reduced. Therefore, there is an advantage that the cost of the printing apparatus can be reduced. This advantage is large in the line head having a large value of the flow rate a or the flow rate F. Therefore, a line head having a long length in the longitudinal direction is advantageous in the line head.

Meanwhile, there are various cases where the first circulation mode is advantageous over the second circulation mode. That is, in the second circulation mode, since the flow rate of the liquid flowing through the liquid ejecting unit 300 is the maximum in the print standby state, the smaller the ejection amount per unit area of an image (hereinafter also referred to as a low-load image), the higher the negative pressure applied to the ejection orifice. Therefore, when the flow path width is narrow and the negative pressure is high, the high negative pressure is applied to the ejection orifice in printing of a low-load image in which unevenness is likely to occur. Therefore, there is a fear that: the print quality is deteriorated in correspondence with an increase in the number of so-called satellite droplets (satellite droplets) ejected following the main droplets of ink.

Meanwhile, in the case of the first circulation mode, since negative pressure is applied to the ejection orifices when an image having a large ejection amount per unit area (hereinafter, also referred to as a high-duty image) is formed, there are advantages as follows: even in the case where many satellites are generated, the influence of the satellites on the image can be made small. These two circulation modes can be desirably selected while taking into account the specifications of the liquid ejection head and the printing apparatus main body (ejection flow rate F, minimum circulation flow rate a, and flow path resistance in the head).

(description of third cycle mode)

Fig. 41 is a schematic diagram showing a third circulation pattern which is one pattern of circulation paths of the printing apparatus applied to the present application example. The description of the same functions and configurations as the first and second circulation modes will be omitted, and only the differences will be mainly described.

In the circulation path, the liquid is supplied to the liquid ejection head 3 from three positions, i.e., two positions at the center of the liquid ejection head 3 and one position at one end of the liquid ejection head 3. The liquid flowing from the common supply flow path 211 to each pressure chamber 23 is recovered by the common recovery flow path 212, and is recovered to the outside from a recovery port located at the other end portion of the liquid ejection head 3. The independent supply flow path 213 communicates with the common supply flow path 211 and the common recovery flow path 212, and the printing element substrate 10 and the pressure chamber 23 disposed therein are provided in the path of the independent supply flow path 213. Therefore, a part of the liquid flowing by the first circulation pump 1002 flows from the common supply flow path 211 to the common recovery flow path 212 while passing through the pressure chambers 23 of the printing element substrate 10 (see the arrow of fig. 41). This is because a pressure difference is generated between the pressure adjustment mechanism H connected to the common supply flow path 211 and the pressure adjustment mechanism L connected to the common recovery flow path 212, and the first circulation pump 1002 is connected only to the common recovery flow path 212.

In this way, in the liquid ejection unit 300, a flow of the liquid passing through the common recovery flow path 212 and a flow of the liquid flowing from the common supply flow path 211 to the common recovery flow path 212 while passing through the pressure chambers 23 in the respective printing element substrates 10 are generated. For this reason, the heat generated by each printing element substrate 10 can be discharged to the outside of the printing element substrate 10 by the flow from the common supply flow path 211 to the common recovery flow path 212 while suppressing the pressure loss. Further, according to the circulation mode, the number of pumps as the liquid transfer unit can be reduced as compared with the first circulation mode and the second circulation mode.

(description of the construction of the liquid ejection head)

The configuration of the liquid ejection head 3 according to the first application example will be explained. Fig. 5A and 5B are perspective views showing a liquid ejection head 3 according to the present application example. The liquid ejection head 3 is a line-type liquid ejection head in which 15 printing element substrates 10 are arranged in series (arranged linearly) in a case where one printing element substrate 10 can eject ink of four colors of cyan C, magenta M, yellow Y, and black K. As shown in fig. 5A, the liquid ejection head 3 includes a printing element substrate 10, a signal input terminal 91, and a power supply terminal 92 capable of supplying electric power to the printing element substrate 10, the signal input terminal 91 and the power supply terminal 92 being electrically connected to each other through the flexible circuit board 40 and the electric wiring substrate 90.

The signal input terminal 91 and the power supply terminal 92 are electrically connected to a control unit of the printing apparatus 1000 in such a manner that an ejection drive signal and power necessary for ejection are supplied to the printing element substrate 10. When the circuit in the electric wiring board 90 is integrated with the wiring, the number of the signal input terminals 91 and the power supply terminals 92 can be reduced compared to the number of the printing element boards 10. Therefore, the number of electrical connection members to be separated when the liquid ejection head 3 is assembled to the printing apparatus 1000 or when the liquid ejection head is replaced is reduced.

As shown in fig. 5B, liquid connection portions 111 provided at both end portions of the liquid ejection head 3 are connected to a liquid supply system of the printing apparatus 1000. Accordingly, inks of four colors including cyan C, magenta M, yellow Y, and black K are supplied from the supply system of the printing apparatus 1000 to the liquid ejection head 3, and the ink flowing through the liquid ejection head 3 is recovered by the supply system of the printing apparatus 1000. In this way, it is possible to circulate the inks of different colors through the path of the printing apparatus 1000 and the path of the liquid ejection head 3.

Fig. 6 is an exploded perspective view showing component parts or units constituting the liquid ejection head 3. The liquid discharge unit 300, the liquid supply unit 220, and the electrical wiring board 90 are mounted on the housing 80. The liquid connection portion 111 (see fig. 3) is provided in the liquid supply unit 220. Further, in order to remove foreign substances in the supplied ink, filters 221 for different colors are provided in the liquid supply unit 220 while communicating with the opening of the liquid connection portion 111 (refer to fig. 2 and 3). The two liquid supply units 220 corresponding to the two colors, respectively, are provided with filters 221. The liquid passing through the filter 221 is supplied to the negative pressure control unit 230 disposed in the liquid supply unit 220 disposed corresponding to each color.

The negative pressure control unit 230 is a unit including negative pressure control valves of different colors. The variation in pressure loss inside the supply system of the printing apparatus 1000 (the supply system on the upstream side of the liquid ejection head 3) caused by the variation in the flow rate of the liquid is greatly reduced by the function of the spring member or the valve provided in the spring member. Therefore, the negative pressure control unit 230 can stabilize the change in the negative pressure on the downstream side of the negative pressure control unit (the liquid ejection unit 300) within a predetermined range. As shown in fig. 2, two negative pressure control valves of different colors are disposed in the negative pressure control unit 230. The two negative pressure control valves are set to different control pressures, respectively. Here, the high-pressure side is communicated with the common supply flow path 211 (see fig. 2) and the low-pressure side is communicated with the common recovery flow path 212 (see fig. 2) in the liquid ejection unit 300 by the liquid supply unit 220.

The casing 80 includes a liquid ejection unit support portion 81 and an electric wiring substrate support portion 82, and the casing 80 ensures rigidity of the liquid ejection head 3 while supporting the liquid ejection unit 300 and the electric wiring substrate 90. The electric wiring substrate support portion 82 is for supporting the electric wiring substrate 90 and is fixed to the liquid ejection unit support portion 81 by screws. The liquid ejection unit support 81 is used to correct warpage or deformation of the liquid ejection unit 300 to ensure relative positional accuracy in the printing element substrate 10. Therefore, streaking (striping) and unevenness of the print medium are suppressed.

For this reason, the liquid ejecting unit support 81 is desired to have sufficient rigidity. A metal such as SUS or aluminum or a ceramic such as alumina is desirable as a material. The liquid ejection unit support 81 is provided with openings 83 and 84 into which the joint rubber 100 is inserted. The liquid supplied from the liquid supply unit 220 is guided to the third flow path member 70 constituting the liquid discharge unit 300 through the joint rubber.

The liquid ejection unit 300 includes a plurality of ejection modules 200 and a flow path member 210, and a cover member 130 is mounted on a surface near a printing medium in the liquid ejection unit 300. Here, as shown in fig. 6, the cover member 130 is a member having a picture frame-like surface and provided with a long opening 131, and the printing element substrate 10 and the sealing member 110 (refer to fig. 10A described later) included in the ejection module 200 are exposed from the opening 131. The peripheral frame of the opening 131 serves as a contact surface of the cap member that covers the liquid ejection head 3 in the print standby state. For this reason, it is desirable to form a closed space in a covered state by applying an adhesive, a sealing material, and a filling material along the periphery of the opening 131 to fill irregularities or spaces on the ejection port surface of the liquid ejection unit 300.

Next, the configuration of the flow path member 210 included in the liquid ejection unit 300 will be described. As shown in fig. 6, the flow path member 210 is obtained by laminating the first flow path member 50, the second flow path member 60, and the third flow path member 70, and the flow path member 210 distributes the liquid supplied from the liquid supply unit 220 to the ejection modules 200. The flow path member 210 is a flow path member that returns the liquid recirculated from the ejection module 200 to the liquid supply unit 220. The flow path member 210 is fixed to the liquid ejecting unit supporting portion 81 with screws, and thus warpage or deformation of the flow path member 210 is suppressed.

Fig. 7 (a) to 7 (f) are diagrams showing front and back surfaces of the first to third flow path members. Fig. 7 (a) shows a surface on which the ejection module 200 is mounted in the first flow path member 50, and fig. 7 (f) shows a surface in contact with the liquid ejection unit support 81 in the third flow path member 70. The first flow path member 50 and the second flow path member 60 are engaged with each other such that portions indicated by (b) of fig. 7 and (c) of fig. 7 and corresponding to the contact surfaces of the flow path members face each other, and the second flow path member and the third flow path member are engaged with each other such that portions indicated by (d) of fig. 7 and (e) of fig. 7 and corresponding to the contact surfaces of the flow path members face each other. Eight common flow paths (211a, 211b, 211c, 211d, 212a, 212b, 212c, 212d) extending in the longitudinal direction of the flow path member are formed by the common flow path grooves 62 and 71 of the flow path member with the second flow path member 60 and the third flow path member 70 joined to each other.

Therefore, a set of the common supply channel 211 and the common collection channel 212 is formed in the channel member 210 corresponding to each color. The ink is supplied from the common supply channel 211 to the liquid ejection head 3 and the ink supplied to the liquid ejection head 3 is recovered through the common recovery channel 212. The communication port 72 (see fig. 7 (f)) of the third flow path member 70 communicates with the hole of the joint rubber 100 and is fluidly connected to the liquid supply unit 220 (see fig. 6). The bottom surface of the common channel groove 62 of the second channel member 60 is provided with a plurality of communication ports 61 (a communication port 61-1 communicating with the common supply channel 211 and a communication port 61-2 communicating with the common recovery channel 212) and communicates with one end portion of the independent channel groove 52 of the first channel member 50. The other end portion of the independent flow path groove 52 of the first flow path member 50 is provided with a communication port 51 and is fluidly connected to the ejection module 200 through the communication port 51. The independent flow channel grooves 52 allow the flow channels to be densely provided on the center side of the flow channel member.

It is desirable that the first to third flow path members be formed of a material that is corrosion-resistant to liquid and has a low linear expansion coefficient. For example, a composite material (resin) obtained by adding an inorganic filler such as fibers or silica microparticles to a base material such as alumina, LCP (liquid crystal polymer), PPS (polyphenylene sulfide), PSF (polysulfone), modified PPE (polyphenylene ether), or the like can be suitably used as the material. As a forming method of the flow path member 210, three flow path members may be laminated and bonded to each other. In the case where a resin composite material is selected as the material, a joining method of welding may be used.

Fig. 8 is a partially enlarged perspective view showing a portion α of (a) of fig. 7, and shows a partially enlarged perspective view when a flow path within the flow path member 210 formed by joining the first to third flow path members to each other is viewed from a surface of the first flow path member 50 on which the ejection module 200 is mounted. The common supply channel 211 and the common recovery channel 212 are formed such that the common supply channel 211 and the common recovery channel 212 are alternately arranged from the channels at both ends. Here, the connection relationship between the flow paths within the flow path member 210 will be described.

The flow path member 210 is provided with a common supply flow path 211(211a, 211b, 211c, 211d) and a common recovery flow path 212(212a, 212b, 212c, 212d) for each color extending in the longitudinal direction of the liquid ejection head 3. The individual supply channels 213(213a, 213b, 213c, 213d) formed by the individual channel grooves 52 are connected to the common supply channel 211 of a different color via the connection port 61. The individual recovery flow paths 214(214a, 214b, 214c, 214d) formed by the individual recovery flow path grooves 52 are connected to the common recovery flow path 212 of a different color through the communication port 61. With this flow path structure, ink can be collectively supplied from the common supply flow path 211 to the printing element substrate 10 located at the center portion of the flow path member through the independent supply flow path 213. Further, the ink can be recovered from the printing element substrate 10 to the common recovery flow path 212 through the independent recovery flow path 214.

Fig. 9 is a sectional view taken along line IX-IX of fig. 8. The independent recovery flow paths (214a, 214c) communicate with the discharge module 200 through the communication port 51. In fig. 9, only the independent recovery flow paths (214a, 214c) are shown, but in a different cross section, as shown in fig. 8, the independent supply flow path 213 and the ejection module 200 communicate with each other. The support member 30 and the printing element substrate 10 included in each ejection module 200 are provided with the following flow paths: the flow path supplies ink from the first flow path member 50 to the printing elements 15 provided on the printing element substrate 10. Further, the support member 30 and the printing element substrate 10 are provided with the following flow paths: this flow path recovers (recirculates) a part or all of the liquid supplied to the printing element 15 to the first flow path member 50.

Here, the common supply flow path 211 of each color is connected to the negative pressure control unit 230 (high pressure side) of the corresponding color through the liquid supply unit 220, and the common recovery flow path 212 is connected to the negative pressure control unit 230 (low pressure side) through the liquid supply unit 220. The negative pressure control means 230 generates a differential pressure (pressure difference) between the common supply channel 211 and the common recovery channel 212. Therefore, as shown in fig. 8 and 9, in the liquid ejection head of the present application example having the flow paths connected to each other, the flows are generated in the order of the common supply flow path 211, the independent supply flow path 213, the printing element substrate 10, the independent recovery flow path 214, and the common recovery flow path 212 for each color.

(Explanation of Ejection Module)

Fig. 10A is a perspective view showing one ejection module 200, and fig. 10B is an exploded view of the ejection module 200. As a manufacturing method of the ejection module 200, first, the printing element substrate 10 and the flexible circuit board 40 are bonded to the support member 30 provided with the liquid communication port 31. Subsequently, the terminals 16 on the printing element substrate 10 and the terminals 41 on the flexible circuit board 40 are electrically connected to each other by wire bonding, and the wire bonding portions (electrical connection portions) are sealed by the sealing member 110.

The terminal 42 of the flexible circuit board 40 opposite to the printing element substrate 10 is electrically connected to the connection terminal 93 of the electric wiring substrate 90 (refer to fig. 6). Since the support member 30 serves as a support body that supports the printing element substrate 10, and the support member 30 serves as a flow path member that fluidically communicates the printing element substrate 10 and the flow path member 210 with each other, it is desirable that the support member has high flatness and sufficiently high reliability when bonded to the printing element substrate. For example, alumina or resin is desirable as the material.

(description of the Structure of the printing element substrate)

Fig. 11A is a plan view showing a surface of the printing element substrate 10 provided with the ejection port 13, fig. 11B is an enlarged view of a portion a of fig. 11A, and fig. 11C is a plan view showing a back surface of fig. 11A. Here, the configuration of the printing element substrate 10 of the present application example will be explained. As shown in fig. 11A, the ejection orifice forming member 12 of the printing element substrate 10 is provided with four ejection orifice arrays corresponding to inks of different colors. The extending direction of the ejection orifice row of the ejection orifices 13 is referred to as "ejection orifice row direction". As shown in fig. 11B, printing elements 15 serving as ejection energy generating elements that eject liquid by thermal energy are arranged at positions corresponding to the respective ejection orifices 13. A pressure chamber 23 provided in the printing element 15 is defined by the partition wall 22.

The printing element 15 is electrically connected to the terminal 16 through an electric wire (not shown) provided to the printing element substrate 10. Then, the printing element 15 boils the liquid while being heated based on a pulse signal input from a control circuit of the printing apparatus 1000 via the electric wiring substrate 90 (refer to fig. 6) and the flexible circuit board 40 (refer to fig. 10B). The liquid is ejected from the ejection port 13 by a foaming force (foaming force) generated by boiling. As shown in fig. 11B, the liquid supply path 18 extends on one side along each ejection orifice row, and the liquid recovery path 19 extends on the other side along the ejection orifice row. The liquid supply path 18 and the liquid recovery path 19 are flow paths extending in the ejection orifice array direction provided to the printing element substrate 10, and the liquid supply path 18 and the liquid recovery path 19 communicate with the ejection orifices 13 through the supply ports 17a and the recovery ports 17 b.

As shown in fig. 11C, a sheet-like cover member 20 is laminated on the back surface of the printing element substrate 10 on which the ejection port 13 is provided, and the cover member 20 is provided with a plurality of openings 21 communicating with the liquid supply path 18 and the liquid recovery path 19. In the present application example, the cover member 20 is provided with three openings 21 for the respective liquid supply paths 18 and two openings 21 for the respective liquid recovery paths 19. As shown in fig. 11B, the opening 21 of the cover member 20 communicates with the communication port 51 shown in fig. 7 (a).

It is desirable that the cover member 20 have sufficient corrosion resistance to liquid. From the viewpoint of preventing color mixing, the opening shape and the opening position of the opening 21 are required to have high accuracy. For this reason, it is desirable to form the opening 21 by photolithography by using a photosensitive resin material or a silicon plate as the material of the cover member 20. In this way, the cover member 20 changes the pitch of the flow path through the opening 21. Here, it is desirable to form the cover member from a membrane-like member having a thin thickness in consideration of pressure loss.

Fig. 12 is a perspective view showing the printing element substrate 10 and the cover member 20 taken along the line XII-XII of fig. 11A. Here, the flow of liquid within the printing element substrate 10 will be explained. The cover member 20 serves as a cover forming a part of the walls of the liquid supply path 18 and the liquid recovery path 19 formed in the substrate 11 of the printing element substrate 10. The printing element substrate 10 is formed by laminating a substrate 11 formed of silicon and an ejection orifice forming member 12 formed of a photosensitive resin, and a cover member 20 is bonded to the back surface of the substrate 11. One surface of the substrate 11 is provided with printing elements 15 (refer to fig. 11B), and the back surface of the substrate 11 is provided with grooves forming a liquid supply path 18 and a liquid recovery path 19 extending along the ejection orifice row.

The liquid supply path 18 and the liquid recovery path 19 formed by the substrate 11 and the cover member 20 are connected to the common supply flow path 211 and the common recovery flow path 212 in each flow path member 210, respectively, and a pressure difference is generated between the liquid supply path 18 and the liquid recovery path 19. When liquid is ejected from the ejection ports 13 to print an image, the liquid in the liquid supply path 18 provided in the substrate 11 flows toward the liquid recovery path 19 through the supply port 17a, the pressure chamber 23, and the recovery port 17b at the ejection port from which the liquid is not ejected by a pressure difference (refer to an arrow C of fig. 12). By this flow, thickened ink, foreign matter, and bubbles generated in the ejection orifice 13 or the pressure chamber 23 due to evaporation from the ejection orifice 13, which are not related to the printing operation, can be recovered by the liquid recovery path 19. Further, the ink of the ejection port 13 or the pressure chamber 23 can be suppressed from thickening.

The liquid recovered in the liquid recovery path 19 is recovered through the opening 21 of the cover member 20 and the liquid communication port 31 (see fig. 10B) of the support member 30 in the order of the communication port 51 (see fig. 7 a), the individual recovery flow path 214, and the common recovery flow path 212 in the flow path member 210. Then, the liquid is recovered by a recovery path of the printing apparatus 1000. That is, the liquid supplied from the printing apparatus main body to the liquid ejection head 3 flows in the order of supply and recovery.

First, the liquid flows from the liquid connecting portion 111 of the liquid supply unit 220 to the liquid ejection head 3. Then, the liquid is supplied sequentially through the joint rubber 100, the communication port 72 and the common channel groove 71 provided in the third channel member, the common channel groove 62 and the communication port 61 provided in the second channel member, and the independent channel groove 52 and the communication port 51 provided in the first channel member. Subsequently, the liquid is supplied to the pressure chamber 23 while sequentially passing through the liquid communication port 31 provided to the support member 30, the opening 21 provided to the cover member 20, and the liquid supply path 18 and the supply port 17a provided to the substrate 11. Among the liquid supplied to the pressure chamber 23, the liquid not ejected from the ejection orifice 13 flows through the recovery port 17b and the liquid recovery path 19 provided in the substrate 11, the opening 21 provided in the cover member 20, and the communication port 31 provided in the support member 30 in this order. Subsequently, the liquid flows through the communication port 51 and the independent flow path groove 52 provided to the first flow path member, the communication port 61 and the common flow path groove 62 provided to the second flow path member, the common flow path groove 71 and the communication port 72 provided to the third flow path member 70, and the joint rubber 100 in this order. Then, the liquid flows from the liquid connecting portion 111 provided to the liquid supply unit 220 to the outside of the liquid ejection head 3.

In the first circulation mode shown in fig. 2, the liquid flowing in from the liquid connection portion 111 is supplied to the joint rubber 100 by the negative pressure control unit 230. Further, in the second circulation mode shown in fig. 3, the liquid recovered from the pressure chamber 23 passes through the joint rubber 100 and flows from the liquid connection portion 111 to the outside of the liquid ejection head through the negative pressure control unit 230. All the liquid flowing from one end of the common supply channel 211 of the liquid discharge unit 300 is not supplied to the pressure chamber 23 through the independent supply channel 213 a.

That is, the liquid can flow from the other end portion of the common supply channel 211 to the liquid supply unit 220 in a state where the liquid flowing in from the one end portion of the common supply channel 211 does not flow to the individual liquid supply channel 213 a. In this way, since the path is provided so that the liquid flows without passing through the printing element substrate 10, even in the case where the printing element substrate 10 includes a large flow path of small flow resistance as in the present application example, the reverse flow of the circulating flow of the liquid can be suppressed. In this way, in the liquid ejection head 3 of the present application example, since the liquid can be suppressed from thickening in the vicinity of the ejection port or the pressure chamber 23, it is possible to suppress a slip (slip) or non-ejection. As a result, a high-quality image can be printed.

(description of positional relationship between printing element substrates)

Fig. 13 is a partially enlarged plan view showing an adjacent portion of the printing element substrate between two adjacent ejection modules. In the present application example, a substantially parallelogram-shaped printing element substrate is used. The ejection orifice arrays (14a to 14d) having the ejection orifices 13 arranged along each printing element substrate 10 are arranged to be inclined in a state of having a predetermined angle with respect to the longitudinal direction of the liquid ejection head 3. Then, at the adjacent portion between the printing element substrates 10, the ejection port arrays are formed such that at least one ejection port overlaps in the printing medium conveying direction. In fig. 13, the two ejection ports overlap each other on a straight line D.

With this configuration, even in the case where the position of the printing element substrate 10 is slightly deviated from the predetermined position, black streaks or white spaces (missing) of the printed image are not seen by the drive control of the overlapped ejection orifices. Even in the case where the printing element substrates 10 are arranged in a straight line (straight line shape) instead of a zigzag shape, it is possible to dispose of black stripes or voids at the connection portions between the printing element substrates 10 while suppressing an increase in length of the liquid ejection heads 3 in the printing medium conveying direction by the configuration shown in fig. 13. Further, in the present application example, the principal plane of the printing element substrate has a parallelogram shape, but the present invention is not limited thereto. For example, even in the case of using a printing element substrate having a rectangular shape, a trapezoidal shape, and other shapes, the configuration of the present invention can be desirably used.

(description of modified example of the configuration of the liquid ejection head)

A modified example of the configuration of the liquid ejection head shown in fig. 40 and fig. 42A to fig. 44 will be explained. The description of the same configuration and function as those of the above-described examples will be omitted, and only the differences will be mainly described. In the present modification, as shown in fig. 40, 42A, and 42B, the liquid connection portion 111 between the liquid ejection head 3 and the outside is arranged concentratedly on one end side in the longitudinal direction of the liquid ejection head. The negative pressure control unit 230 is centrally arranged on the other end side of the liquid ejection head 3 (see fig. 43). The liquid supply unit 220 belonging to the liquid ejection head 3 is configured as a long unit corresponding to the length of the liquid ejection head 3, and includes flow paths and filters 221 corresponding to the four liquids to be supplied, respectively. As shown in fig. 43, the positions of the openings 83 to 86 provided at the liquid ejection unit support 81 are also located at positions different from the above-described liquid ejection head 3.

Fig. 44 shows a laminated state of the flow path members 50, 60, and 70. The printing element substrate 10 is linearly arranged on the upper surface of the flow path member 50 positioned at the uppermost layer among the flow path members 50, 60, and 70. As channels communicating with the openings 21 (fig. 17) formed on the back surface side of each printing element substrate 10, two independent supply channels 213 and one independent recovery channel 214 are provided for the liquid of each color. Therefore, as the openings 21 formed in the cover member 20 provided on the rear surface of the printing element substrate 10, two supply openings 21 and one recovery opening 21 are provided for the liquid of each color. As shown in fig. 44, the common supply channel 211 and the common recovery channel 212 extending in the longitudinal direction of the liquid ejection head 3 are alternately arranged.

(second application example)

Hereinafter, configurations of the inkjet printing apparatus 2000 and the liquid ejection head 2003 according to a second application example of the present invention will be described with reference to the drawings. In the following description, only differences from the first application example will be described, and descriptions of the same constituent components as those of the first application example will be omitted.

(Explanation of ink jet printing apparatus)

Fig. 21 is a diagram showing an inkjet printing apparatus 2000 according to the present application example for ejecting liquid. The printing apparatus 2000 of the present application example differs from the first application example in that a full-color image is printed on a printing medium by a configuration in which four single-color liquid ejection heads 2003 are arranged in parallel corresponding to inks of cyan C, magenta M, yellow Y, and black K, respectively. In the first application example, the number of the ejection orifice arrays for one color is one. However, in the present application example, the number of ejection orifice arrays for one color is twenty. For this reason, in the case where the print data is appropriately distributed to a plurality of ejection port arrays to print an image, the image can be printed at a higher speed.

Further, even in the case where there is an ejection port from which liquid is not ejected, liquid can be ejected complementarily from ejection ports of other rows located at positions corresponding to the non-ejection ports in the printing medium conveyance direction. Reliability is improved and thus commercial images can be properly printed. As in the first application example, the supply system of the printing apparatus 2000, the buffer tank 1003 (see fig. 2 and 3), and the main tank 1006 (see fig. 2 and 3) are fluidly connected to the liquid ejection head 2003. Further, an electric control unit that sends electric power and an ejection control signal to the liquid ejection head 2003 is electrically connected to the liquid ejection head 2003.

(description of circulation route)

As in the first application example, the first circulation mode and the second circulation mode shown in fig. 2 or 3 can be used as the liquid circulation mode between the printing apparatus 2000 and the liquid ejection head 2003.

(description of the Structure of the liquid ejection head)

Fig. 14A and 14B are perspective views showing a liquid ejection head 2003 according to the present application example. Here, the structure of the liquid ejection head 2003 according to the present application example will be explained. The liquid ejection head 2003 is a line-type (page-wide type) inkjet printhead that includes 16 printing element substrates 2010 arranged linearly in a longitudinal direction of the liquid ejection head 2003 and is capable of printing an image by one type of liquid. As in the first application example, the liquid ejection head 2003 includes a liquid connection portion 111, a signal input terminal 91, and a power supply terminal 92. However, since the liquid ejection head 2003 of the present application example includes a plurality of ejection orifice rows, the signal input terminal 91 and the power supply terminal 92 are arranged on both sides of the liquid ejection head 2003, as compared with the first application example. This is because it is necessary to reduce a voltage drop or a signal transmission delay caused by a wiring portion provided in the printing element substrate 2010.

Fig. 15 is an oblique exploded view showing the liquid ejection head 2003 and constituent parts or units constituting the liquid ejection head 2003 according to their functions. The functions of the respective units and members or the order of liquid flow in the liquid ejection head are basically the same as those of the first application example, but the function of ensuring the rigidity of the liquid ejection head is different. In the first application example, the rigidity of the liquid ejection head is mainly ensured by the liquid ejection unit support 81, but in the liquid ejection head 2003 of the second application example, the rigidity of the liquid ejection head is ensured by the second flow path member 2060 included in the liquid ejection unit 2300.

The liquid ejection unit support portions 81 of the present application example are connected to both end portions of the second flow path member 2060, and the liquid ejection unit 2300 is mechanically connected to the carriage of the printing apparatus 2000 to position the liquid ejection head 2003. The electric wiring substrate 90 and the liquid supply unit 2220 including the negative pressure control unit 2230 are connected to the liquid ejection unit support part 81. Both liquid supply units 2220 include a filter (not shown) disposed.

Two negative pressure control units 2230 are set to control the pressures of different, relatively high and low negative pressures. Further, as shown in fig. 14B and 15, in the case where the negative pressure control units 2230 on the high pressure side and the low pressure side are provided at both end portions of the liquid ejection head 2003, the liquid flows in the common supply flow path and the common recovery flow path extending in the longitudinal direction of the liquid ejection head 2003 are opposed to each other in the extending direction. In this configuration, heat exchange between the common supply flow path and the common recovery flow path is promoted, and thus the temperature difference in the two common flow paths is reduced. Therefore, the temperature difference of the printing element substrates 2010 disposed along the common flow path is reduced. As a result, there are the following advantages: the printing unevenness is not easy to be caused by the temperature difference.

Next, the detailed configuration of the flow path member 2210 of the liquid ejection unit 2300 will be described. As shown in fig. 15, a flow path member 2210 is obtained by laminating a first flow path member 2050 and a second flow path member 2060, and the flow path member 2210 distributes the liquid supplied from the liquid supply unit 2220 to the ejection modules 2200. The flow path member 2210 serves as a flow path member for returning the liquid recirculated from the ejection module 2200 to the liquid supply unit 2220. The second flow path member 2060 of the flow path member 2210 is a flow path member in which the common supply flow path and the common recovery flow path are formed, and improves the rigidity of the liquid ejection head 2003. For this reason, the material of the second flow path member 2060 is desired to have sufficient corrosion resistance against liquid and high mechanical strength. Specifically, SUS, Ti, or alumina can be used.

Fig. 16 (a) is a view showing a surface of the first flow path member 2050 on which the ejection module 2200 is mounted, and fig. 16 (b) is a view showing a back surface of the first flow path member 2050 and a surface in contact with the second flow path member 2060. Unlike the first application example, the first flow path member 2050 of the present application example has the following structure: in this configuration, the plurality of members are respectively disposed adjacent to the ejection modules 2200 in correspondence therewith. By adopting such a division structure, a plurality of modules can be arranged in accordance with the length of the liquid ejection head 2003. Therefore, this structure can be suitably used for a relatively long liquid ejection head corresponding to, for example, paper having a size of B2 or more, in particular.

As shown in fig. 16 (a), the communication port 51 of the first flow path member 2050 is in fluid communication with the ejection module 2200. As shown in fig. 16 (b), the independent communication port 53 of the first flow path member 2050 is in fluid communication with the communication port 61 of the second flow path member 2060. Fig. 16 (c) shows a contact surface of the second flow path member 60 with respect to the first flow path member 2050, fig. 16 (d) shows a cross section of the thickness direction center portion of the second flow path member 60, and fig. 16 (e) shows a contact surface of the second flow path member 2060 with respect to the liquid supply unit 2220. The function of the communication port or the flow channel of the second flow path member 2060 is the same as that of one color of the first application example. The common channel groove 71 of the second channel member 2060 is formed such that one side thereof is a common supply channel 2211 and the other side thereof is a common recovery channel 2212 as shown in fig. 17. These flow paths are respectively provided along the longitudinal direction of the liquid ejection head 2003 so that the liquid is supplied from one end of the flow path to the other end of the flow path. The present application example differs from the first application example in that the liquid flow directions in the common supply passage 2211 and the common recovery passage 2212 are opposite to each other.

Fig. 17 is a perspective view showing a liquid connection relationship between the printing element substrate 2010 and the flow path member 2210. A pair of a common supply flow path 2211 and a common recovery flow path 2212 extending in the longitudinal direction of the liquid ejection head 2003 are provided in the flow path member 2210. The communication port 61 of the second flow path member 2060 is connected to the independent communication port 53 of the first flow path member 2050 such that the two positions are fitted to each other, and the liquid supply flow path is formed as follows: the liquid supply flow path communicates with the communication port 51 of the first flow path member 2050 through the communication port 61 from the common supply flow path 2211 of the second flow path member 2060. Likewise, the following liquid supply paths are also formed: the liquid supply path communicates with the communication port 51 of the first channel member 2050 via the common recovery flow path 2212 from the communication port 72 of the second channel member 2060.

Fig. 18 is a sectional view taken along line XVIII-XVIII of fig. 17. The common supply flow path 2211 is connected to the ejection module 2200 through the communication port 61, the independent communication port 53, and the communication port 51. Although not shown in fig. 18, it is apparent that the common recovery flow path 2212 is connected to the ejection module 2200 through the same path in different cross sections of fig. 17. As in the first application example, the ejection module 2200 and the printing element substrate 2010 are each provided with a flow path communicating with each ejection port, and thus a part or all of the supplied liquid can be recirculated while passing through the ejection port where the ejection operation is not performed. Further, as in the first application example, the common supply passage member 2211 is connected to the negative pressure control unit 2230 (high pressure side) and the common recovery passage 2212 is connected to the negative pressure control unit 2230 (low pressure side) by the liquid supply unit 2220. Thus, a flow is formed such that the liquid flows from the common supply flow path member 2211 to the common recovery flow path 2212 through the pressure chambers of the printing element substrate 2010 due to the pressure difference.

(Explanation of Ejection Module)

Fig. 19A is a perspective view showing one ejection module 2200, and fig. 19B is an exploded view of the ejection module 2200. The difference from the first application example is that the terminals 16 are arranged on both sides of the ejection orifice row direction of the printing element substrate 2010 (long side portions of the printing element substrate 2010), respectively. Thus, two flexible circuit boards 40 electrically connected to the printing element substrates 2010 are arranged for each printing element substrate 2010. Since the number of ejection orifice arrays provided to the printing element substrate 2010 is twenty, the ejection orifice arrays are more than the eight ejection orifice arrays of the first application example. Here, since the maximum distance between the terminal 16 and the printing element is shortened, a decrease in voltage or a signal delay generated in the wiring portion provided in the printing element substrate 2010 is reduced. Further, the liquid communication port 31 of the support member 2030 opens along all the ejection port arrays provided to the printing element substrate 2010. The other configurations are the same as those of the first application example.

(description of the Structure of the printing element substrate)

Fig. 20 (a) is a schematic view showing a face of the printing element substrate 2010 on which the ejection outlet 13 is arranged, and fig. 20 (c) is a schematic view showing a back face of the face of fig. 20 (a). Fig. 20 (b) is a schematic diagram illustrating a surface of the printing element substrate 2010 in a case where the cover member 2020 provided on the back surface of the printing element substrate 2010 in fig. 20 (c) is removed. As shown in (b) of fig. 20, the liquid supply path 18 and the liquid recovery path 19 are alternately provided on the back surface of the printing element substrate 2010 in the direction of the ejection orifice row.

The number of ejection orifice arrays is larger than that of the first application example. However, the essential difference from the first application example is that the ground terminals 16 are arranged on both side portions of the printing element substrate in the ejection orifice array direction as described above. The basic configuration is the same as that of the first application example, a pair of the liquid supply path 18 and the liquid recovery path 19 are provided in each ejection orifice row and the cover member 2020 is provided with an opening 21 communicating with the liquid communication port 31 of the support member 2030.

(third application example)

The configurations of the ink jet printing apparatus 1000 and the liquid ejection head 3 according to the third application example of the present invention will be explained. A liquid ejection head of a third application example is a page-wide liquid ejection head that prints an image on a B2-sized printing medium by one scan. Since the third application example is the same as the second application example in many respects, only the differences from the second application example will be mainly described in the following description, and the description of the same configuration as the second application example will be omitted.

(Explanation of ink jet printing apparatus)

Fig. 45 is a schematic diagram showing an inkjet printing apparatus according to the present application example. The printing apparatus 1000 has the following configuration: in this configuration, an image is not directly printed on a printing medium by the liquid ejected from the liquid ejection head 3. That is, first, the liquid is ejected to the intermediate transfer member (intermediate transfer drum 1007) to form an image on the intermediate transfer member, and the image is transferred to the printing medium 2. In the printing apparatus 1000, liquid ejection heads 3 respectively corresponding to inks of four Colors (CMYK) are arranged in a circular arc shape along an intermediate transfer drum 1007. Accordingly, the full-color printing process is performed on the intermediate transfer member, the printed image is appropriately dried on the intermediate transfer member, and the image is transferred to the printing medium 2 conveyed by the paper conveying roller 1009 through the transfer portion 1008. The paper conveying system of the second application example is mainly used for conveying single sheets of paper in a horizontal direction. However, the paper conveying system of the present application example can also be applied to continuous paper fed from a main roller (not shown). In such a drum conveyance system, since the paper is conveyed while a predetermined tension is applied to the paper, conveyance jam hardly occurs even in a high-speed printing operation. For this reason, the reliability of the apparatus is improved, and thus the apparatus is suitable for commercial printing purposes. As in the first and second application examples, the supply system, the buffer tank 1003, and the main tank 1006 of the printing apparatus 1000 are fluidly connected to the respective liquid ejection heads 3. Further, an electric control unit that transmits an ejection control signal and electric power to the liquid ejection heads 3 is electrically connected to each liquid ejection head 3.

(fourth circulation mode explanation)

As in the second application example, the first circulation path and the second circulation path shown in fig. 2 or 3 can also be used as the liquid circulation paths between the liquid ejection head 3 and the tank of the printing apparatus 1000, but the circulation paths shown in fig. 46 are desirable. The main difference from the second circulation path of fig. 3 is that a bypass valve 1010 is additionally provided in communication with each flow path of the first circulation pumps 1001 and 1002 and the second circulation pump 1004. The bypass valve 1010 has a function (first function) of reducing the upstream pressure of the bypass valve 1010 by opening a valve when the pressure exceeds a predetermined pressure. Further, the bypass valve has a function (second function) of opening and closing the valve at an arbitrary timing by a signal from a control substrate of the printing apparatus main body.

By the first function, it is possible to suppress large or small pressure from being applied to the downstream side of the first circulation pumps 1001 and 1002 or the upstream side of the second circulation pump 1004. For example, when the functions of the first circulation pumps 1001 and 1002 cannot function normally, there are cases where a large flow rate or pressure may be applied to the liquid ejection head 3. Therefore, there is a fear that liquid may leak from the ejection orifice of the liquid ejection head 3 or that each bonded portion within the liquid ejection head 3 may be broken. However, when a bypass valve is added to the first circulation pumps 1001 and 1002 as in the present application example, the bypass valve 1010 is opened if there is a large pressure. Therefore, the liquid flow path is opened to the upstream side of each circulation pump, and therefore the above-described problem can be suppressed.

Further, when the circulation driving action is stopped, all the bypass valves 1010 are quickly opened based on the control signal of the printing apparatus main body after the actions of the first circulation pumps 1001 and 1002 and the second circulation pump 1004 are stopped by the second function. Therefore, the high negative pressure (for example, several kPa to several tens kPa) at the downstream portion of the liquid ejection head 3 (between the negative pressure control portion 230 and the second circulation pump 1004) can be released in a short time. When a displacement pump such as a diaphragm pump is used as the circulation pump, a check valve is generally provided in the pump. However, when the bypass valve is opened, the pressure at the downstream portion of the liquid ejection head 3 can also be released from the downstream buffer tank 1003. Although the pressure at the downstream portion of the liquid ejection head 3 can be released only from the upstream side, pressure loss exists in the upstream flow path of the liquid ejection head and the flow path inside the liquid ejection head. For this reason, since it takes some time when the pressure is released, the internal pressure of the common flow path in the liquid ejection head 3 is instantaneously excessively lowered. Therefore, there is a fear that the meniscus of the ejection orifice may break. However, since the downstream pressure of the liquid ejection head is further released when the bypass valve 1010 on the downstream side of the liquid ejection head 3 is opened, the risk of the meniscus of the ejection orifice breaking is reduced.

(description of the Structure of the liquid ejection head)

The structure of a liquid ejection head 3 according to a third application example of the present invention will be described. Fig. 47A is a perspective view showing the liquid ejection head 3 according to the present application example, and fig. 47B is an exploded perspective view of the liquid ejection head 3. The liquid ejection head 3 is an ink-jet pagewidth type print head that includes thirty-six printing element substrates 10 arranged in a linear shape (linear shape) along the length direction of the liquid ejection head 3 and prints an image by one color. As in the second application example, the liquid ejection head 3 includes the protector 132, and the protector 132 protects the rectangular side surface of the head in addition to the signal input terminal 91 and the power supply terminal 92.

Fig. 47B is an exploded perspective view of the liquid ejection head 3, which shows that the constituent members or units constituting the liquid ejection head 3 are divided according to their functions (the shield 132 is not shown). The functions of the units and the members or the order of circulating the liquid in the liquid ejection head 3 are the same as in the second application example. The main difference from the second application example is that the separate electric wiring board 90 and the negative pressure control unit 230 are arranged at different positions, and the first flow path member has a different shape. As in the present application example, for example, in the case of a liquid ejection head 3 having a length corresponding to a B2-sized printing medium, the power consumed by the liquid ejection head 3 is large, and therefore eight electric wiring boards 90 are provided. Four electrical wiring boards 90 are mounted on each of both side surfaces of the long electrical wiring board support portion 82 mounted to the liquid ejecting unit support portion 81.

Fig. 48A is a side view showing a liquid ejection head 3 including a liquid ejection unit 300, a liquid supply unit 220, and a negative pressure control unit 230, fig. 48B is a schematic view showing a flow of liquid, and fig. 48C is a perspective view showing a cross section taken along a line xlviic-xlviic of fig. 48A. A part of the configuration is simplified for easy understanding of the drawings.

The liquid connection part 111 and the filter 221 are provided in the liquid supply unit 220, and the negative pressure control unit 230 is integrally formed at a lower side of the liquid supply unit 220. Therefore, the distance in the height direction between the negative pressure control unit 230 and the printing element substrate 10 becomes shorter than in the second application example. With this configuration, the number of flow path connection portions in the liquid supply unit 220 is reduced. As a result, there are the following advantages: the reliability of preventing the printing liquid from leaking is improved, and the number of constituent parts or steps is reduced.

Further, since the water head difference between the negative pressure control unit 230 and the ejection port formation surface is relatively reduced, the configuration can be applied to a printing apparatus in which: in this printing apparatus, the inclination angles of the respective liquid ejection heads 3 shown in fig. 45 are different. Since the water head difference can be reduced, even when the liquid ejection heads 3 having different inclination angles are used, the negative pressure difference applied to the ejection orifices of the printing element substrate can be reduced. Further, since the distance from the negative pressure control unit 230 to the printing element substrate 10 is reduced, the flow resistance between the negative pressure control unit 230 and the printing element substrate 10 is reduced. Therefore, a pressure loss difference caused by a change in the liquid flow rate is reduced, and thus the negative pressure can be more desirably controlled.

Fig. 48B is a schematic view illustrating the flow of the printing liquid within the liquid ejection head 3. Although the circulation path differs from that shown in fig. 46 in terms of the circuit, fig. 48B shows the flow of the liquid in the constituent components of the actual liquid ejection head 3. A pair of a common supply flow path 211 and a common recovery flow path 212 extending in the longitudinal direction of the liquid ejection head 3 are provided in the long second flow path member 60. The common supply flow path 211 and the common recovery flow path 212 are formed such that the liquids flow in opposite directions within the common supply flow path 211 and the common recovery flow path 212, and a filter 221 is provided on the upstream side of each flow path to capture foreign matter that has intruded from the connection portion 111 or the like. In this way, since the liquid flows through the common supply flow path 211 and the common recovery flow path 212 in opposite directions, it is possible to desirably reduce the temperature gradient in the longitudinal direction within the liquid ejection head 3. To simplify the explanation of fig. 46, the flows in the common supply flow path 211 and the common recovery flow path 212 are shown in the same direction.

The negative pressure control unit 230 is connected to the downstream side of each of the common supply flow path 211 and the common recovery flow path 212. The common supply channel 211 is provided with a branching portion in the middle of being connected to the individual supply channel 213a, and the common recovery channel 212 is provided with a branching portion in the middle of being connected to the individual recovery channel 213 b. An independent supply flow path 213a and an independent recovery flow path 213b are formed in the first flow path member 50, and each independent supply flow path communicates with an opening 21 (see (c) of fig. 11) of the cover member 20 provided at the back surface of the printing element substrate 10.

The negative pressure control unit 230 represented by "H" and "L" of fig. 48B is a unit of the high pressure side (H) and the low pressure side (L). The negative pressure control unit 230 is a back pressure type pressure adjustment mechanism that controls the upstream pressure of the negative pressure control unit 230 to a high negative pressure (H) and a low negative pressure (L). The common supply flow path 211 is connected to the negative pressure control unit 230 (high pressure side), and the common recovery flow path 212 is connected to the negative pressure control unit 230 (low pressure side), so that a pressure difference is generated between the common supply flow path 211 and the common recovery flow path 212. By this pressure difference, the liquid flows from the common supply channel 211 to the common recovery channel 212, and simultaneously passes through the individual supply channel 213a, the ejection port 11 (pressure chamber 23) in the printing element substrate 10, and the individual recovery channel 213b in this order.

Fig. 48C is a perspective view showing a cross section taken along line xlviic-xlviic of fig. 48A. In the present application example, each of the ejection modules 200 includes the first flow path member 50, the printing element substrate 10, and the flexible circuit board 40. In the present embodiment, the support member 2030 (fig. 18) described in the second application example is not present, and the printing element substrate 10 including the cover member 20 is directly joined to the first flow path member 50. The liquid is supplied from the communication port 61 formed in the upper surface of the common supply flow path 211 provided in the second flow path member to the independent supply flow path 213a through the independent communication port 53 formed in the lower surface of the first flow path member 50. Subsequently, the liquid passes through the pressure chamber 23, and passes through the independent recovery flow path 213b, the independent communication port 53, and the communication port 61 to be recovered to the common recovery flow path 212.

Here, unlike the second application example shown in fig. 15, the independent communication port 53 formed in the lower surface of the first flow path member 50 (the surface close to the second flow path member 60) is sufficiently large relative to the communication port 61 formed in the upper surface of the second flow path member 60. With this configuration, even when positional deviation occurs when the ejection module 200 is attached to the second flow path member 60, the first flow path member and the second flow path member can reliably be in fluid communication with each other. As a result, the yield in the head manufacturing process is improved, and thus cost reduction can be achieved.

The description of the above application example does not limit the scope of the present invention. As an example, in the present application example, a thermal driving manner (thermal type) in which bubbles are generated by a heating element to eject liquid has been described. However, the present invention can also be applied to a liquid ejection head that employs a piezoelectric method and other various liquid ejection methods.

In the present application example, an inkjet printing apparatus (printing apparatus) in which liquid such as ink is circulated between a liquid tank and a liquid ejection head has been described, but other application examples may also be used. In other applicable examples, for example, a configuration may be adopted in which ink is not circulated and two reservoirs are provided on the upstream side and the downstream side of the liquid ejection head in such a manner that ink flows from one reservoir to the other reservoir. In this way, the ink in the pressure chamber can flow.

In the present application example, an example of a so-called line head having a length corresponding to the width of a printing medium has been described, but the present invention can also be applied to a so-called serial type liquid ejection head that prints an image on a printing medium while scanning the printing medium. As the serial type liquid ejection head, for example, the liquid ejection head may be equipped with a printing element substrate that ejects black ink and a printing element substrate that ejects color ink, but the present invention is not limited thereto. That is, a liquid ejection head which is shorter than the width of the printing medium and includes a plurality of printing element substrates arranged such that ejection orifices overlap with each other in the ejection orifice array direction may be provided, and the printing medium may be scanned by the liquid ejection head.

Embodiments of the present invention will be described below.

(first embodiment)

Referring to fig. 22A to 28C, a liquid ejection head according to a first embodiment of the present invention will be described. The liquid supply path of the above application example corresponds to the first common supply flow path of the present embodiment. Likewise, the liquid recovery path corresponds to the first common recovery flow path, the first communication port corresponds to the opening, the common supply path corresponds to the third common supply flow path, and the common recovery path corresponds to the third common recovery flow path.

Fig. 22A to 22M are exploded views illustrating a liquid ejection head according to an embodiment of the present invention. Fig. 22A to 22G are exploded perspective views showing component parts. Fig. 22H to 22M are exploded top views corresponding to fig. 22B to 22G illustrating constituent members. Fig. 23A to 23G are schematic views showing the structure of one ejection orifice row 3024 of the plurality of ejection orifice rows 3024 shown in fig. 22A. Fig. 23A to 23D are perspective views corresponding to fig. 22A to 22D, respectively. Fig. 23E to 23G are plan views corresponding to fig. 22H to 22J, respectively. Further, fig. 24A is a sectional view taken along line XXIVa-XXIVa of fig. 23E to 23G. Fig. 24B is a cross-sectional view taken along line XXIVb-XXIVb. Fig. 25 is an equivalent circuit diagram showing a part of the liquid ejection head of the present embodiment. Fig. 26A and 26B are equivalent circuit diagrams showing a part of the liquid ejection head of the present embodiment and pressure distribution in the flow path. Fig. 27 is a plan view showing the shape of the printing element substrate of the present embodiment. Fig. 28A to 28C are schematic perspective views showing the end of the ejection orifice array.

As shown in fig. 22A to 24B, the liquid ejection head of the present embodiment has a six-layer laminated flow path structure including an ejection orifice forming member 3012, a first flow path layer 3011, a second flow path layer 3050, a third flow path layer 3060, a fourth flow path layer 3070, a fifth flow path layer 3080, and a sixth flow path layer 3090.

The ejection orifice forming member 3012 is provided with a plurality of ejection orifice arrays 3024, and each ejection orifice array 3024 has a plurality of ejection orifices 3013 arranged in a row. The first flow path layer 3011 has the following configuration: in this configuration, a printing element 3015 that generates energy for ejecting liquid is provided at a position corresponding to the ejection port 3013. The ejection orifice forming member 3012 and the first flow path layer 3011 are stacked so that a space for forming a pressure chamber 3023 and a flow path 3310 are formed between the ejection orifice forming member 3012 and the first flow path layer 3011 (fig. 24A and 24B). The liquid ejection head can eject liquid such as ink located in the pressure chamber 3023 (the flow path 3310) from the ejection ports 3013 by energy generated by the print element 3015. The pressures in the flow path 3310 and the pressure chamber 3023 are maintained in a negative pressure state in a rest state, so that the meniscus of the liquid (ink) in the ejection orifice 3013 protrudes inward. When this pressure change is generated in the pressure chamber, ejection characteristics such as a liquid ejection speed or a volume of ejected liquid droplets are affected.

As shown in fig. 22A to 22C and fig. 22H to 22I, in the present embodiment, a plurality of ejection orifice arrays 3024 are densely arranged at 600 dpi. The first common supply channel 3313 and the first common recovery channel 3314 are formed along the main surface of the second channel layer 3050. The third flow path layer 3060 is provided with a first communication port 3315a (supply-side communication port) and a first communication port 3315b (recovery-side communication port). The first flow path layer 3011 is provided with a print element row in which print elements 3015 are arranged and a through hole row in which through holes 3017 for supplying and recovering liquid are arranged. As shown in fig. 24A and 24B, the through-hole 3017 includes a supply port 3017a and a recovery port 3017B. The plurality of supply ports 3017a extend in a direction (second direction) intersecting a face on which the print elements 3015 are provided to form supply flow paths, and the plurality of supply ports 3017a are arranged in an arrangement direction (first direction) of the print elements 3015 serving as a row direction of the ejection port rows to form the supply port rows. Similarly, the plurality of recovery ports 3017b extend in a direction (second direction) intersecting with the surface on which the printing elements 3015 are provided to form a recovery flow path, and the plurality of recovery ports 3017b are arranged in the arrangement direction (first direction) of the printing elements 3015 serving as the row direction of the ejection port row to form a recovery port row.

As shown in fig. 24A and 24B, the first common supply passage 3313 communicates with the passage 3310 and the pressure chamber 3023 through the supply port 3017 a. Similarly, the first common recovery passage 3314 communicates with the passage 3310 and the pressure chamber 3023 through the recovery port 3017 b. The first common supply passage 3313 receives liquid from a first communication port 3315a (supply-side communication port) formed in the third passage layer 3060. Similarly, the first common recovery flow path 3314 communicates with the first communication port 3315b (recovery-side communication port) formed in the third flow path layer 3060. As shown in fig. 22D and 22J, the plurality of first communication ports 3315a are arranged in a direction intersecting with the row direction of the ejection orifice row to form a first communication port row. The plurality of first communication ports 3315b are also arranged in the same direction to form a first communication port row.

As shown in fig. 22E to 22G and 22K to 22M, the fourth channel layer 3070 is provided with a second common supply channel 3331 and a second common recovery channel 3332. The fifth channel layer 3080 is provided with a second communication port 3333a (supply-side communication port) and a second communication port 3333b (collection-side communication port). The sixth channel layer 3090 is provided with the third common supply channel 3335 and the third common collection channel 3336.

The first common supply channel 3313 of the second channel layer 3050 communicates with the plurality of supply ports 3017a on one surface side and communicates with the first communication port 3315a on the other surface side. Similarly, the first common recovery flow path 3314 of the second flow path layer 3050 communicates with the recovery ports 3017b on one surface side and communicates with the first communication port 3315b on the other surface side. The second common supply channel 3331 of the fourth channel layer 3070 communicates with the first communication port 3315a on one surface side and communicates with the plurality of second communication ports 3333a on the other surface side. Similarly, the second common recovery channel 3332 of the fourth channel layer 3070 communicates with the first communication port 3315b on one surface side and communicates with the second communication port 3333b on the other surface side. Here, at least one of the first communicating port 3315a and the first communicating port 3315b is provided at a plurality of positions. The third common supply flow channel 3335 of the sixth flow channel layer 3090 communicates with the plurality of second communication ports 3333 a. Similarly, the third common collection flow channel 3336 of the sixth flow channel layer 3090 communicates with the plurality of second communication ports 3333 b.

The plurality of first communication ports 3315a (first supply-side communication ports) are arranged in a direction (third direction) intersecting with the row direction (first direction) of the ejection port row to form a first supply-side communication port row. The plurality of first communication ports 3315b (first recovery-side communication ports) are arranged in a direction (third direction) intersecting with the row direction (first direction) of the ejection port row to form a first recovery-side communication port row.

The plurality of second communication ports 3333a (second supply-side communication ports) are arranged in the row direction (first direction) of the ejection port row to form a second supply-side communication port row. The plurality of second communication ports 3333b (second recovery-side communication ports) are arranged in the row direction (first direction) of the ejection port row to form a second recovery-side communication port row.

The arrangement density of the plurality of second communication ports 3333a and the arrangement density of the plurality of second communication ports 3333b are smaller than the arrangement density of the plurality of first communication ports 3315a and the arrangement density of the plurality of first communication ports 3315 b. The arrangement density of the first communication ports 3315a and 3315b is smaller than the arrangement density of the supply ports 3017a and the arrangement density of the recovery ports 3017 b. The first common supply passages 3313 and the first common recovery passages 3314 extend in the first direction, and the first common supply passages 3313 and the first common recovery passages 3314 are alternately arranged in parallel in a third direction intersecting the first direction. The second common supply channel 3331 and the second common collection channel 3332 extend in a third direction intersecting the first direction, and the second common supply channel 3331 and the second common collection channel 3332 are alternately arranged in parallel in the first direction. The third common supply channel 3335 and the third common collection channel 3336 extend in the first direction.

The liquid ejection head of the present embodiment can have the following configuration: this structure is formed by stacking a plurality of flow path layers so that the density of the flow paths gradually increases from the sixth flow path layer 3090 toward the first flow path layer 3011. Therefore, it is possible to provide a liquid ejection head having a plurality of ejection orifice rows arranged densely while suppressing an increase in the size of the printing element substrate and each flow path member.

The flow of liquid (hereinafter, referred to as ink) of the liquid ejection head of the present embodiment will be described. Ink supplied from the outside flows into the liquid ejection head from the third common supply flow path 3335 serving as an inflow port. Next, the ink is supplied to the flow path 3310 (the pressure chamber 3023) while sequentially passing through the second communication port 3333a, the second common supply flow path 3331, the first communication port 3315a, the first common supply flow path 3313, and the supply port 3017 a. Subsequently, the ink flows to the outside from the third common recovery flow path 3336 serving as an outflow port while sequentially passing through the recovery port 3017b, the first common recovery flow path 3314, the first communication port 3315b, the second common recovery flow path 3332, the second communication port 3333b, and the third common recovery flow path 3336.

When the ink is forcibly flowed in this way, thickening of the ink in the ejection head can be suppressed. As a result, a decrease in ink ejection speed or modulation of color density of each printed dot can be suppressed. Hereinafter, in this specification, such forced flow of ink is referred to as "ink circulation flow".

The present embodiment has the following configuration to suppress a pressure change of each pressure chamber or a flow rate change of an ink circulation flow in each pressure chamber. That is, as shown in fig. 23A to 23G, the first communication port 3315a communicates with one first common supply passage 3313. Similarly, the first communication port 3315b communicates with one first common recovery passage 3314. Here, at least one of the first communicating port 3315a and the first communicating port 3315b is provided at a plurality of positions. The first communication port 3315a and the first communication port 3315b are arranged so that a change in the flow rate of the ink circulation flow in each pressure chamber 3023 or a change in the pressure of each pressure chamber does not have a large influence on the ejection characteristics. Specifically, one ejection orifice row 3024 has the following configuration: in this structure, the first communication ports 3315a and 3315b are alternately arranged in the row direction with respect to the ejection port row. The alternate arrangement can narrow the interval between the first communication ports 3315a and 3315 b. That is, even when the first common supply flow path 3313 and the first common recovery flow path 3314 have relatively narrow flow path widths, it is possible to suppress variations in the flow rate of the ink circulation flow in each pressure chamber 3023 (each flow path 3310) or variations in the pressure of each pressure chamber.

The first communication port 3315a and the first communication port 3315b are arranged as follows. First, of the plurality of pressure chambers 3023 (flow paths 3310), the flow path resistance of the flow path including the pressure chamber 3023 (flow path 3310) between the first common recovery flow path 3314 and the first common supply flow path 3313 is denoted by "r". In addition, in the first common supply flow path 3313, the flow path resistance of the flow path between the adjacent supply ports 3017a (i.e., the supply flow path) is denoted by "R". Similarly, in the first common recovery flow path 3314, the flow path resistance of the flow path between the adjacent recovery ports 3017b (i.e., the recovery flow path) is represented by "R". The flow rate of ink flowing through each of the channels 3310 (pressure chambers 3023) is represented by "q" as an average flow rate, "Δ q" as a flow rate difference between a maximum flow rate and a minimum flow rate in a range where the discharge characteristics are not affected, that is, the variation in landing position or color unevenness does not affect the image, and "X" as a ratio therebetween (that is, the flow rate ratio X is Δ q/q). At this time, the first communication ports 3315 are arranged so that the number N of the ejection ports between the first communication ports 3315a and 3315b satisfies the following expression.

[ formula 1]

When the first communication port 3315a and the first communication port 3315b are arranged under such conditions, it is possible to suppress a flow rate variation of the ink circulation flow between the pressure chambers in the pressure chamber 3023 (the flow path 3310) to a flow rate difference that does not affect the ejection characteristics.

Equation (1) for suppressing the variation in the flow rate of the ink circulation flow between the pressure chambers of the respective pressure chambers 3023 will be described in detail with reference to fig. 25. Fig. 25 is an equivalent circuit diagram showing a portion between the first communication port 3315a and the first communication port 3315b adjacent to each other with respect to the first direction. A case where N pressure chambers 3023 (flow paths 3310) are provided between the first communication port 3315a and the first communication port 3315b adjacent to each other will be described.

In this case, the maximum amount of ink flows to the pressure chamber 3023 (the pressure chamber 1 in fig. 25) closest to the first communication port 3315a and the pressure chamber 3023 closest to the first communication port 3315b among the N pressure chambers 3023. Further, a minimum amount of ink flows to the pressure chamber 3023 located in the middle of the first communication port 3315a and the first communication port 3315b among the N pressure chambers 3023. When the maximum flow rate and the minimum flow rate are represented by "Q1" and "Q2", respectively, and the average value of the flow rates of the inks flowing in the respective pressure chambers 3023 is represented by "Q", the total amount Q of the supplied ink satisfies the relationship Q — Nq.

The pressure loss p1 of the ink is represented by the following formula: the ink flows from the first communication port 3315a to the pressure chamber 3023 (the pressure chamber 1 in fig. 25) closest to the first communication port 3315a and flows through the first common recovery passage 3314 to reach the first communication port 3315 b.

[ formula 2]

The pressure loss p of the ink is represented by the following formula₂: ink flows from the first common supply passage 3313 through the first communication port 3315a, passes through a pressure chamber (pressure chamber 2 in fig. 25) located between the first communication port 3315a and the first communication port 3315b, and passes through the first common recovery passage 3314 to reach the first communication port 3315 b.

[ formula 3]

Due to pressure loss p₁And pressure loss p₂Are equal to each other, so that the maximum flow rate q of ink flowing through each pressure chamber₁And minimum flow q₂The flow rate difference Δ q' therebetween satisfies the following equations from equations (2) and (3).

[ formula 4]

Here, in order to prevent the influence on the ejection characteristics, it is necessary to make q the flow rate difference Δ q' between the maximum flow rate and the minimum flow rate of the ink flowing through each pressure chamber₁-q₂And the average flow rate q of ink flowing through each pressure chamber is set to a predetermined flow rate ratio X or less. For this reason, the conditions in the following formula are required.

[ formula 5]

When equation (5) is modified by the number N of pressure chambers that focus on between the first communication port 3315a and the first communication port 3315b, equation (1) is obtained.

In the embodiment of the present invention, when the flow rate of the ink circulation flow is increased and decreased by a certain ratio or more, the ink recovery effect obtained by the ink circulation flow in the lower portion of the ejection orifice is changed. Therefore, it is understood that the ejection speed or the ejected droplet volume changes or the color density may change greatly. In particular, in the non-limiting example of the present embodiment, in the case where the flow rate is increased and decreased by 10% with respect to a certain flow rate of the ink circulation flow, the ejection speed or the ejected droplet volume is changed, and thus the color density is largely changed. In addition, in this example, in the case where the ratio Δ q/q between the average flow rate and the flow rate difference between the maximum flow rate and the minimum flow rate is set to the predetermined flow rate ratio X0.2 or less, the ejection characteristic or the color density is not greatly affected.

Next, an example of the influence on the flow rate variation of the ink circulation flow will be described with reference to fig. 37.

Fig. 37 is a graph showing a non-limiting example of the relationship between the flow rate of the ink circulation flow (circulation flow rate) in the lower portion of each ejection port and the ejection speeds as follows: when the ink circulates at each circulation flow rate, the ink ejection speed is the ink ejection speed of the first droplet ejection after the ink ejection operation is temporarily stopped for a predetermined time. In this example, under the condition that the boundary line is set in the vicinity of the circulation flow rate of 7000pl/s, in the case where the circulation flow rate is about 7000pl/s or more, the ink of the first droplet can be ejected at the ejection speed equal to or higher than 90% of the normal ejection speed. In contrast, in the case where the circulation flow rate is less than about 7000pl/s, the ejection speed of the ink of the first droplet is lower than about 90% of the normal ejection speed. When the ink ejection speed is reduced, positional deviation may occur when the ejected ink reaches (lands on) a printing medium, and thus deterioration in image quality occurs.

Therefore, in order to prevent deterioration of image quality due to positional deviation during the landing operation, it is important to increase the circulation flow rate to a certain extent so as to suppress a decrease in the ink ejection speed after the ink ejection operation is temporarily stopped for a predetermined time.

Here, fig. 36 shows an example of an ink supply system that can be applied to the liquid ejection head of the present invention. In fig. 36, the liquid ejection head 3003 is in fluid communication with a first upstream reservoir 3044 and a second downstream reservoir 3045. The first reservoir 3044 supplies ink to the third common supply flow path 3335. The supplied ink passes through the second common supply flow path 3331 and the first common supply flow path 3313 while flowing through the respective communication ports to be supplied to the pressure chamber 3023 (flow path 3310). Further, the ink passes through the first common recovery flow path 3314 and the second common recovery flow path 3332 while flowing from the pressure chamber 3023 (flow path 3310) through each communication port, and the ink is recovered from the third common recovery flow path 3336 to the second reservoir 3045. In this structure, as a method of generating an ink circulation flow, there is a method of using a water head difference between the first reservoir 3044 and the second reservoir 3045. Further, there are methods of controlling the pressure of the first and second reservoirs 3044, 3045 and using the pressure differential between the first and second reservoirs 3044, 3045. Further, there is a method of generating a flow by a pump or the like.

However, when the circulation flow rate is increased by a pump or the like or a pressure difference between the first reservoir 3044 and the second reservoir 3045, it tends to be difficult to control the pressure at the lower portion of the discharge port. Therefore, in consideration of the difficulty of pressure control and the degradation of image quality due to the positional deviation of ink during the landing operation, the circulation flow rate can be set small so that the ejection speed is not lowered excessively.

As described above, in the present embodiment, the first communication ports 3315a and 3315b are respectively disposed in the first common supply passage 3313 and the first common recovery passage 3314 such that at least one of the first communication ports 3315a and 3315b is provided at a plurality of positions to satisfy formula (1). Therefore, the value of the flow rate difference between the maximum flow rate and the minimum flow rate and the ratio of the average flow rate (flow rate ratio) X can be reduced while the ratio R/R of the fluid resistance is fixed. That is, variations in the flow rate of the ink circulation flow between the pressure chambers of the pressure chambers 3023 can be suppressed without widening the channel widths of the first common supply channel 3313 and the first common recovery channel 3314. Therefore, since a decrease in the ejection speed of the liquid droplets or a modulation in the color density due to evaporation of the moisture from the ejection ports 3013 can be suppressed, a high-quality image can be formed with high accuracy.

Similarly, in the present embodiment, a pressure change between the pressure chambers of the pressure chambers 3023 can be suppressed. The pressure loss generated in the first common supply passage 3313 or the first common recovery passage 3314 is a pressure change between the pressure chambers of the respective pressure chambers in the row direction of the ejection port row. That is, when the pressure change is represented by "Δ P", the following equation is established.

[ formula 6]

Here, when the maximum pressure variation allowed in a range not affecting the ejection characteristics is represented by "Δ Pm", the first communication ports 3315a and 3315b are arranged so that the number N of ejection ports therebetween satisfies the following expression.

[ formula 7]

In this way, in the present embodiment, the plurality of first communication ports 3315a and the plurality of first communication ports 3315b are respectively arranged in the first common supply passage 3313 and the first common recovery passage 3314 so as to satisfy formula (7). Therefore, pressure variations between the pressure chambers of the respective pressure chambers can be suppressed without widening the channel width of the first common supply channel 3313 or the first common recovery channel 3314. Therefore, since a change in the ink ejection speed or a change in the volume of the ejected ink droplets can be suppressed, a high-quality image can be formed with high accuracy.

Further, in order to suppress a flow rate change of the ink circulation flow between the pressure chambers respectively corresponding to the ejection ports 3013 arranged densely or a pressure change between the pressure chambers of the pressure chambers, it is preferable that the present embodiment has the following configuration. That is, as shown in fig. 22A to 22M, the second common supply flow path 3331 extends in a direction (third direction) intersecting with the row direction (first direction) of the ejection port row 3024, and communicates with the plurality of first communication ports 3315a arranged in the third direction. Similarly, the second common recovery flow path 3332 extends in a third direction intersecting the row direction (first direction) of the ejection port row 3024, and communicates with the plurality of first communication ports 3315b arranged in the third direction. The plurality of second common supply flow paths 3331 are integrated into one flow path corresponding to the third common supply flow path 3335 through the second communication port 3333 a. Similarly, the plurality of second common collection channels 3332 are integrated into one channel corresponding to the third common collection channel 3336 through the second communication port 3333 b.

In this manner, in this embodiment, the flow path is connected to the ejection port forming member 3012 by a six-layer structure including the first flow path layer 3011, the second flow path layer 3050, the third flow path layer 3060, the fourth flow path layer 3070, the fifth flow path layer 3080, and the sixth flow path layer 3090. Therefore, the plurality of first common supply passages 3313 arranged at a narrow pitch in the plurality of ejection port rows 3024 arranged densely can be integrated, and the first communication ports 3315a are arranged so as to satisfy the formula (1). Similarly, the plurality of first common recovery passages 3314 arranged at a narrow pitch in the plurality of ejection port rows 3024 arranged densely can be integrated, and the first communication ports 3315b are arranged so as to satisfy the formula (1). That is, the ejection port rows can be densely formed without widening the flow path widths of the first common supply flow path 3313 and the first common recovery flow path 3314. Further, it is possible to suppress a flow rate variation of an ink circulation flow between pressure chambers in the respective pressure chambers 23 (flow paths 3310) corresponding to the ejection ports 3013 of the plurality of ejection port arrays 3024 arranged densely, or a pressure variation between pressure chambers in the respective pressure chambers. Further, while suppressing a change in the flow rate of the ink circulation flow in each pressure chamber 3023 (flow path 3310) or a change in the pressure in each pressure chamber, ink can be easily supplied from the reservoir to the ejection ports 3013 arranged densely and recovered to the reservoir. Therefore, there are the following advantages: a liquid ejection head having a compact size can be provided, and an entire system of a liquid ejection apparatus having a compact size including the liquid ejection head can be provided.

The present embodiment is particularly effective in the case where the number of pressure chambers 3023 respectively arranged at the ejection orifice arrays 3024 is large (for example, 100 or more) and the arrangement density of the plurality of ejection orifice arrays 3024 (the arrangement density of the ejection orifice arrays in the direction intersecting the ejection orifice arrays) is high (for example, 50dpi or more). In this case, even when the ratio (R/R) between the pressure chamber and the flow path resistance of the flow path is small (for example, about 1/1000), there is a tendency that the flow rate of the ink circulation flow is not uniform. That is, in the case where the number of ejection orifices constituting the ejection orifice array is further increased or the interval between the ejection orifice arrays is narrowed, the configuration of the present invention can be effectively used to suppress the pressure change of each pressure chamber or the flow rate change of the ink circulation flow of each pressure chamber. In particular, the configuration of the present invention is effective for the following line head: the line head is a liquid ejection head having a length corresponding to the width of a printing medium and liquid ejection heads in which ejection orifices are densely arranged at 600dpi or more.

Next, in this embodiment, a case where ink is ejected from a plurality of ejection ports 3013 will be described. In order to suppress a change in the flow rate of the ink circulation flow in the pressure chamber 3023 that is temporarily stopped when ink is ejected from the plurality of ejection ports 3013, the present embodiment preferably has the following configuration. Here, "I" indicates the flow rate of ink ejected from each ejection port 3013. At this time, the first communication ports 3315a and 3315b are arranged so that the number N of the ejection ports 3013 therebetween satisfies the following expression.

[ formula 8]

In the present embodiment, the first communication port 3315a and the first communication port 3315b are arranged under this condition. Therefore, when ink is ejected from the plurality of ejection ports 3013, the flow rate variation of the ink circulation flow between the pressure chambers of the pressure chambers 3023 that are temporarily stopped can be suppressed to a flow rate difference that does not affect the ejection characteristics.

Referring to fig. 26A and 26B, expression (8) for suppressing a change in the flow rate of the ink circulation flow in the pressure chamber 3023 that is temporarily stopped in the case of ejecting ink from the plurality of ejection ports 3013 will be described in detail.

In the case where an ink circulation flow is generated at a flow rate sufficient to suppress the influence caused by evaporation of moisture from the ejection ports 3013, there is a case where the amount of ink ejected from the plurality of ejection ports 3013 is larger than the flow rate of the ink circulation flow. In this case, as shown in fig. 26A, the ink of the first common recovery flow path 3314 flows reversely. That is, in fig. 26A, the ink flows in the first common supply passage 3313 in a direction from the first communication port 3315a toward the first communication port 3315b as indicated by an arrow. Further, at the plurality of pressure chambers 3023, ink is ejected from ejection orifices at a flow rate I. Therefore, the ink flows in the first common recovery flow path 3314 in a direction from the first communication port 3315b toward the first communication port 3315 a.

Fig. 26B shows a graph obtained by imaging the relationship between the pressure distributions of the first common supply passage 3313 and the first common recovery passage 3314 at this time. In this graph, the horizontal axis represents the relative position L in the direction from the first communication port 3315a located adjacent to the first communication port 3315b, and the vertical axis represents the pressure P. When the ink ejection operation from the pressure chamber 3023 is temporarily stopped in the state shown in fig. 26A, the ratio of the amounts of ink supplied from the pressure chambers to the first common supply channel 3313 and the first common recovery channel 3314 is set to t: 1-t. At this time, when the pressure loss generated in the first common supply flow path 3313 is represented by "Δ Pin 1" and the pressure loss generated in the first common recovery flow path 3314 is represented by "Δ Pout 1", the following two equations are established.

[ formula 9]

[ formula 10]

Further, the pressure generated in each pressure chamber on the first common supply passage 3313 side is denoted by "Pin", the pressure generated in the first common recovery passage 3314 side is denoted by "Pout", the maximum value of the pressure change in each pressure chamber is denoted by "Δ Pmax", and the minimum value of the pressure change in each pressure chamber is denoted by "Δ Pmin". At this time, since the equation of Δ Pmax ═ Pin-Pout + Δ Pout1 and the equation of Δ Pmin ═ Pin-Pout- Δ Pin1 are established, the change in the flow rate Δ q' of the ink circulation flow is expressed by the following equation.

[ formula 11]

In order to set the variation in the flow rate Δ q' of the ink circulation flow at a predetermined flow rate ratio X or less, the condition of the following formula is necessary.

[ formula 12]

When equation (12) is modified by the number N of pressure chambers that focus on between the first communication port 3315a and the first communication port 3315b, equation (8) is obtained.

Here, in the present embodiment, the first common supply flow path 3313 and the first common recovery flow path 3314 of the liquid ejection head as a non-limiting example of the present invention are set to have a flow path width of 200 μm and a flow path height of 500 μm. Further, the ejection ports 3013 of the ejection port array 3024 are arranged at a density of 600dpi, and the flow path 3310 located below the ejection ports 3013 is formed in a shape having a flow path width of 30 μm, a flow path height of 14 μm, and a flow path length of 100 μm. In the liquid ejection head, a case where ink was ejected when the flow rate of the ink circulation flow in the lower portion of the ejection orifice was set to 0.01m/s, the ejection amount was set to 5pl, and the drive frequency was set to 10kHz was examined. In this case, when the number N of the ejection ports between the first communication port 3315a and the first communication port 3315b is set to about 65 or less, the influence on the flow rate variation can be suppressed.

In this way, in the present embodiment, the first communication ports 3315a and 3315b are respectively arranged in the first common supply passage 3313 and the first common recovery passage 3314 such that at least one of the first communication ports 3315a and 3315b is provided at a plurality of positions so as to satisfy formula (8). Therefore, the value of the flow rate ratio X can be reduced while the ratio R/R of the flow path resistance is fixed. That is, the flow rate of the ink circulation flow in the pressure chamber 3023 (the flow path 3310) which is temporarily stopped when the ink is ejected from the plurality of ejection ports can be suppressed from varying, and the flow path widths of the first common supply flow path 3313 and the first common recovery flow path 3314 can be prevented from increasing. Therefore, since a decrease in the ejection speed of the droplets of the ink or a modulation in the color density due to evaporation of the moisture from the ejection ports 3013 can be suppressed, a high-quality image can be formed with high accuracy.

Further, in order to suppress a pressure change of each pressure chamber or a flow rate change of an ink circulation flow in each pressure chamber, it is desirable that the present embodiment has the following configuration. That is, the first communication ports 3315a and 3315b arranged at both ends of the ejection port row 3024 in the row direction are formed in a shape having an opening area smaller than that of the first communication ports 3315a and 3315b arranged at positions other than both ends.

The ejection ports 3013 are arranged only on one side in the row direction of the ejection port row when viewed from the first communication port 3315a or the first communication port 3315b arranged at both ends. For this reason, the total ink amount Q of the ink passing through the first communication port 3315a or the first communication port 3315b is smaller than the total ink amount of the ink passing through the first communication port 3315a or the first communication port 3315b arranged at a position different from both end portions in the row direction of the ejection port row. For this reason, when the flow path resistance increases while the first communication ports 3315a or 3315b at both end portions are formed smaller than the center portion, the pressure loss generated in the first communication ports 3315a or 3315b arranged at positions different from the end portions can be made substantially uniform. Thus, it is possible to reduce a difference between an ink circulation flow passing through the pressure chamber communicating with the first communication port 3315a or the first communication port 3315b at both end portions and an ink circulation flow passing through the pressure chamber communicating with the first communication port 3315a or the first communication port 3315b arranged at different positions. Therefore, the flow rate variation of the ink circulation flow in each pressure chamber can be further suppressed.

Referring to fig. 27, 28A to 28C, another embodiment will be explained. In order to suppress a change in the flow rate of the ink circulation flow in each pressure chamber 3023, the present embodiment has the following configuration.

Fig. 27 is a plan view showing a printing element substrate of the liquid ejection head of the present embodiment. As shown in fig. 27, in the print element substrate 3010 of the present embodiment, the area between the end of the ejection port row 3024 and the end of the print element substrate 3010 is large. For example, a driving circuit or a board which transmits and receives an electric signal to and from the printing element substrate 3010 is disposed in this region.

Fig. 28A to 28C are schematic top perspective views illustrating a part of one ejection orifice array 3024 in the liquid ejection head of the present embodiment. In fig. 28A to 28C, arrows indicate the direction of the ink circulation flow. In the case of the print element substrate 3010 shown in fig. 27, as shown in fig. 28A and 28B, the first communication ports 3315B are arranged so as to overlap the ejection ports 3013 located at the ends of the ejection port array 3024. In contrast, fig. 28C shows an example in which the first communication port 3315b is arranged so as not to overlap with the end of the ejection port 3013. According to the configuration of fig. 28A and 28B, the length of the ink flowing from the first communication port 3315a located at the end of the ejection orifice row 3024 to the first communication port 3315B through the pressure chamber 3023 can be shortened as compared with the configuration of fig. 28C. That is, according to the arrangement shown in fig. 28A or 28B, the maximum pressure loss occurring in the first common supply flow path 3313 and the first common recovery flow path 3314 located in the vicinity of the end portion of the ejection port row 3024 can be reduced. For this reason, a change in the flow rate of the ink circulation flow in each pressure chamber 3023 can be suppressed. The same applies to a structure in which the first communication ports 3315a, not the first communication ports 3315b, are arranged so as to overlap with the ejection ports at the end of the ejection port row 24.

Referring to fig. 22A to 22M, another embodiment will be explained. In order to suppress the temperature distribution in the chip (printing element substrate 3010), the present embodiment has the following configuration. That is, as shown in fig. 22D and 22J, the first communication ports 3315 located at both ends in the row direction of the ejection orifice row 3024 are formed as the first communication ports 3315 b.

In the case of forcibly circulating the ink of each pressure chamber as in the configuration of the present embodiment, when the heat emitted from the printing element 3015 or the like is substantially absorbed by the liquid (ink), the temperature of the recovery-side ink flowing out from the pressure chamber may increase. Further, there are cases where: even when an ink circulation flow is generated at a flow rate sufficient to suppress the influence caused by evaporation of moisture in the ejection ports 3013, the amount of ink ejected from the plurality of ejection ports 3013 increases. At this time, ink is also supplied from the first communication port 3315b through the third common recovery flow path 3336. That is, there are cases where: when ink is ejected from the plurality of liquid ejection ports 3013, high-temperature ink is supplied from the first communication port 3315 b. Therefore, the temperature near the first communication port 3315b is higher than the temperature near the first communication port 3315a, and thus a difference in ejection speed occurs between the ejection port 3013 located near the first communication port 3315a and the ejection port 3013 located near the first communication port 3315 b. Thus, the first communication ports 3315 located at both end portions of the ejection orifice row 3024 are arranged such that the first communication port 3315a is arranged at one end portion and the first communication port 3315b is arranged at the other end portion, and when viewed from the entire ejection orifice row 3024, a temperature distribution that is inclined in the row direction is generated. For this reason, the thermal distribution width in the entire chip increases. As a result, variations in ejection characteristics occur in the entire chip. That is, when the first communication ports 3315b corresponding to the same kind of flow path are arranged at both end portions in the row direction of the ejection port row 3024, the inclined temperature distribution can be suppressed. Thus, variations in ejection characteristics can be suppressed.

In fig. 22D and 22J, the first communication ports 3315b are disposed at both end portions, but even when the first communication ports 3315a are disposed at both end portions, an inclined temperature distribution can be suppressed. However, as shown in fig. 22D and 22J, it is desirable to arrange the first communication ports 3315b at both ends in the row direction of the ejection orifice row 3024. In the print element substrate 3010 of the present embodiment, a region where the ejection port 3013 is not present between the end of the print element substrate 3010 and each of the two ends of the ejection port row 3024 is large, and heat generated by the ink ejection operation is emitted from this region. For this reason, there is a tendency that: in the case of ejecting ink from a plurality of ejection orifices 3013, the temperature at both ends in the row direction of the ejection orifice row 3024 is lower than the temperature at other positions. In contrast, when the first communication ports 3315b are arranged at both end portions, high-temperature ink can be supplied to both end portions, and the temperatures at both end portions can be further increased. Therefore, the temperature difference with respect to other positions can be reduced. That is, since the temperature distribution in the entire chip can be reduced, the variation in the ejection characteristics can be suppressed.

In addition, although the structure in which the first communication port 3315a and the first communication port 3315 are provided at a plurality of positions has been described in the present embodiment, the present invention may have a structure in which at least one of the first communication port 3315a and the first communication port 3315 is provided at a plurality of positions. That is, the present invention also includes a structure in which at least one of the first communication port 3315a and the first communication port 3315b is provided at a plurality of positions and variation in ejection characteristics is suppressed. For example, the present invention also includes a structure in which the first communicating port 3315a is provided at two positions and the first communicating port 3315b is provided at one position. Further, as another example, the present invention includes a structure in which the first communicating port 3315a is provided at one position and the first communicating port 3315b is provided at two positions.

Further, the relationship between the constituent members and the flow path layer of each embodiment of the present invention does not limit the present invention. In the configuration of the ejection orifice forming member and the first to sixth flow path layers, the liquid ejection head may be obtained by laminating different members. Further, the liquid ejection head can be obtained by integrally molding a plurality of layers. As an example, the following two configuration examples can be exemplified. With the first configuration example, the first flow path layer 3011 and the second flow path layer 3050 are integrated as the print element substrate 10 of the above-described application example. Specifically, the supply port 3017a, the recovery opening 2017b, the first common supply path 3313, and the first common recovery path 3314 are formed in the Si substrate on which the print element 3015 is provided. The third flow channel layer 3060 is formed on the cover member 20 or 2020, and a part of the fourth flow channel layer 3070 is formed on the support member 30 of fig. 10. The other part of the fourth channel layer 3070 is formed in the first channel member 50 of fig. 7, and part of the fifth channel layer 3080 and the sixth channel layer 3090 is formed in the second channel member 60. The other part of the sixth flow channel layer 3090 is formed in the third flow channel member 70. In the second configuration example, the first flow path layer 3011 and the second flow path layer 3050 are formed on the printing element substrate 10 of the above-described application example. The third flow channel layer 3060 is formed on the cover member 20 or 2020, and a part of the fourth flow channel layer 3070 is formed on the support member 2030. The other parts of the fourth channel layer 3070 and the fifth channel layer 3080 are formed in the first channel member 2050, and the sixth channel layer 3090 is formed in the second channel member 2060. In addition, the first flow path layer 3011 may be formed on the printing element substrate 10, and the second flow path layer 3050 may be formed on the second substrate.

(liquid ejection head manufacturing step)

Fig. 38 shows an example of a manufacturing step of the liquid ejection head of the present embodiment. As shown in fig. 38, in the present example, first, in step S91, an ejection orifice forming member 3012 is formed on a printing element substrate 3010 having a printing element 3015 or forming necessary circuits to form an ejection orifice (ejection orifice forming step). Next, in step S92, the supply port 3017a and the recovery port 3017b are formed on the back surface of the printing element substrate 3010, which is the surface opposite to the ejection port formation surface (back surface supply/recovery flow path forming step). Next, in step S93, the cover member 20 is formed on the back surface of the printing element substrate 10 so as to cover the supply port 3017a and the recovery port 3017b (cover member forming step). Next, in step S94, the printing element substrate 10 having the stacked structure obtained in step S93 is processed from the wafer shape (wafer shape) into a chip shape (chipshape) (cutting step). Further, in step S95, the printing element substrate 10 obtained as a chip in step S94 is bonded to the support member 30 (bonding step).

In this way, in the present example, the third flow path layer 3060 (cover member 20) is formed on the back surface of the printing element substrate 3010 (printing element substrate 10) by the cover member forming step (S93) before the bonding step (S95). Therefore, the first communication port 3315a and the first communication port 3315b can be formed in a wafer step of processing the substrate into a wafer shape. Since the cover member 20 is formed by a wafer step, the accuracy of the member is satisfactory as compared with the case where the member is formed by machining or molding. For this reason, a fine hole can be formed with high accuracy. Further, the cover member 20 can be formed thin. Thus, the ejection ports can be densely arranged. Further, the flow path resistance of the first communication port 3315a or the first communication port 3315b can be reduced, and the variation thereof can be reduced. Therefore, the pressure difference that generates the ink circulation flow can be stabilized, and the circulation flow rate change can be reduced.

Here, the cover member 20 may be formed of a silicon substrate from the viewpoint of manufacturing steps. That is, since the cover member 20 formed of a wafer-shaped silicon substrate is bonded to the wafer-shaped printing element substrate 10, the number of steps can be reduced as compared with the case where the cover member 20 is bonded to a chip obtained by cutting the wafer.

Alternatively, the cover member 20 may be formed of a resin film. Since the cover member 20 can be bonded by laminating a film-like resin on the wafer-like printing element substrate 10 as in the case of forming the cover member by a silicon substrate, the number of steps of bonding the cover member to each chip can be reduced.

Here, the order or contents of the steps of the embodiment are merely examples of the present invention, and do not limit the present invention. That is, the order of the ejection orifice forming step, the back surface supply/recovery flow path forming step, the cap member forming step, and the cutting step does not limit the present invention, and the cap member forming step (S93) may be performed before the joining step (S95).

(second embodiment)

Referring to fig. 29A to 32D, a liquid ejection head according to a second embodiment of the present invention will be described. The same reference numerals will be given to the same constituent elements as those of the above-described embodiment, and the description thereof will be omitted.

Fig. 29A to 29M are exploded views showing main parts of a liquid ejection head according to an embodiment of the present invention. Fig. 29A to 29G are exploded perspective views illustrating constituent members, and fig. 29H to 29M are exploded plan views illustrating constituent members.

Fig. 30 is a plan view showing the shape of the printing element substrate of the liquid ejection head of the present embodiment. Fig. 31 is a schematic perspective view showing a liquid ejection head and showing an end of an ejection orifice array. Fig. 32 is a diagram showing changes in the circulation flow rate in the present embodiment. Fig. 32A and 32B are top perspective views illustrating the printing element substrate, and fig. 32C and 32D are diagrams illustrating pressure distributions in the first common supply flow path and the first common recovery flow path.

As shown in fig. 30, the printing element substrate 4010 of the present embodiment is formed in a parallelogram shape, and an area between an end of the ejection orifice row 3024 and an end of the printing element substrate 4010 is small as compared with the configuration of the printing element substrate 3010 of the first embodiment shown in fig. 27. In this case, a driver circuit or a board which transmits and receives an electric signal to and from the outside and is provided in the printing element substrate 4010 is disposed on the long side of the printing element substrate 4010. In this embodiment mode, such a printing element substrate 4010 is used. Therefore, even in a line head in which a plurality of printing element substrates 4010 are arranged in a substantially one row shape instead of a zigzag shape, ejection orifice rows of adjacent printing element substrates 4010 can overlap each other in the scanning direction at adjacent portions between printing element substrates 4010. Here, the scanning direction means a relative movement direction of the liquid ejection head with respect to the medium when a printing action is performed on the medium by the liquid ejection head. In addition, the shape of a substantial row indicates a state in which the adjacent printing element substrates 4010 are partially overlapped in the scanning direction and the longitudinal direction of the liquid ejection head (arrangement direction of the printing element substrates).

As shown in fig. 30, in the second embodiment, the ejection port 3013 is arranged near the end of the printing element substrate 4010. As described above with reference to fig. 28A and 28B, in the first embodiment, the first communication port 3315a or the first communication port 3315B is arranged at a position overlapping with an end portion in the ejection orifice row direction of the printing element substrate 3010. However, in the second embodiment, it is difficult to arrange the first communication port 3315a or the first communication port 3315b at a position overlapping with the end portion in the ejection orifice row direction of the printing element substrate 4010 because the positional relationship of these members is different from that in the first embodiment. Therefore, as shown in fig. 31, the first communication port 3315a and the first communication port 3315b are arranged at positions separated toward the center side in the row direction of the ejection port row 3024 with respect to the end portion of the ejection port row.

In order to suppress temperature distribution in the printing element substrate 4010, pressure variation of each pressure chamber (each channel), and flow rate variation of an ink circulation flow between pressure chambers (between channels), the present embodiment has the following configuration. That is, as shown in fig. 29H and 29J, the first communication port 3315a is arranged on both end sides in the row direction of the ejection port row 3024.

Fig. 32A to 32D are diagrams illustrating an example of a state in which liquid is ejected from a plurality of ejection orifices. In fig. 32A and 32B, arrows indicate the flow direction of ink, and Δ Pin2, Δ Pout2, Δ Pin3, and Δ Pout3 each indicate a pressure loss generated in each flow path. Fig. 32C shows a pressure distribution corresponding to the state of fig. 32A, and fig. 32D shows a pressure distribution corresponding to the state of fig. 32B. In fig. 32C and 32D, a solid line indicates the pressure in the first common supply passage 3313, and a two-dot chain line indicates the pressure in the first common recovery passage 3314.

As shown in fig. 32A, in the case where the first communication port 3315 located at the end portion in the row direction of the ejection port row is formed as the first communication port 3315a, a pressure difference between the first common supply flow path 3313 located at the end portion of the ejection port row 3024 and the first common recovery flow path 3314 is represented by "Δ P2". Similarly, as shown in fig. 32B, in the case where the first communication port 3315 located at the end portion in the row direction of the ejection port row is formed as the communication port 3315B, the pressure difference between the first common supply flow path 3313 and the first common recovery flow path 3314 located at the end portion of the ejection port row 3024 is represented by "Δ P3". At this time, the following equation is established.

Δ P2 ═ (Pin- Δ Pin2) - (Pout- Δ Pout2) ═ (Pin-Pout) + (Δ Pout2- Δ Pin2) … formula (13)

Δ P3 ═ P- Δ Pin3) - (Pout- Δ Pout3 ═ P-Pout) - (Δ Pin3- Δ Pout3) … formula (14)

Here, the pressure loss satisfies the relationships of Δ Pout2 > Δ Pin2 and Δ Pin3 > Δ Pout3 based on the positional relationship between the end portion of the ejection orifice row and the first communication port 3315 (the first communication port 3315a and the first communication port 3315 b). Therefore, the differential pressure Δ P2 is larger than the initial differential pressure (Pin-Pout) in the initial non-ejection state, and the differential pressure Δ P3 is smaller than the initial differential pressure. When the pressure difference is reduced, the amount of ink circulation flow is reduced, thereby reducing the effect of suppressing the decrease in the ejection speed of the liquid droplet or the modulation of the color density caused by the evaporation of the moisture in the ejection orifice. Therefore, the influence is larger than the case where the differential pressure increases. Therefore, when the first communication ports 3315a are arranged at both end portions in the row direction of the ejection port row 3024, the influence of the flow rate variation can be reduced.

Further, in order to generate the ink circulation flow, the pressure of the first communication port 3315a is set to be higher than that of the first communication port 3315 b. Therefore, the ink can be easily supplied during the ink ejection operation. The first communication port 3315a through which ink can be easily supplied is arranged near the end of the ejection orifice row 3024. Therefore, the pressure loss occurring in the first common supply flow path 3313 or the first common recovery flow path 3314 when ink is ejected from the plurality of ejection ports can be adjusted to be smaller than that in the case where the communication port 3315b is arranged in the vicinity of the end of the ejection port row 24.

Further, as shown in fig. 30, in the present embodiment, unlike the first embodiment, in the printing element substrate 4010, an area where no ejection port (printing element) exists between an end of the printing element substrate 4010 and each of both ends in a row direction of the ejection port row 3024 is small.

In the case of this structure, heat generated by the ink ejection action is confined to be radiated from the region. On the contrary, the lengths of the first common supply passage 3313 and the first common recovery passage 3314 in the row direction from the first communication port 3315a or the first communication port 3315b to the ejection port row 3024 are both increased. Ink flowing through a long flow path easily receives heat from the printing element substrate 4010. Then, there is a tendency that the temperature at both end portions in the row direction of the ejection orifice row 3024 is higher than the temperature at other positions when the ink is ejected from the plurality of ejection orifices 3013. Further, the pressure loss generated in each flow path during the ink ejection operation increases due to the length of the flow path. Therefore, the pressure at the end of the ejection orifice row 3024 tends to become uneven.

In contrast, in the present embodiment, the first communication ports 3315a are arranged at both end portions of the ejection port row 3024. Therefore, a larger amount of ink is supplied from the first communication ports 3315a corresponding to the first communication ports 3315 arranged at positions near the ejection ports 3013 near the end portions in the row direction of the ejection port row 3024 than the amount of ink supplied from the first communication ports 3315 b. Thus, since the amount of high-temperature ink supplied from the first communication port 3315b is reduced when ink is ejected from the plurality of ejection ports 3013, a temperature rise at the end of the ejection port array 3024 can be reduced.

In this way, in the present embodiment, when the first communication ports 3315a are arranged at both ends in the row direction of the ejection port row 3024, the influence of the flow rate change, the pressure change, or the temperature distribution in the chip can be suppressed. Therefore, since variations in ejection characteristics can be suppressed, or reduction in the ejection speed of droplets or modulation of color density due to evaporation of water in the ejection openings can be suppressed, high-quality images can be formed with high accuracy.

Next, a temperature distribution in the entire printing element substrate 4010 of the present embodiment will be described with reference to fig. 39A to 39D. Fig. 39A to 39D are graphs showing temperature distributions when ink is ejected from all the ejection orifices in the row direction of the ejection orifice row 3024. The printing element substrate 4010 is controlled at a temperature of 50 ℃.

A case where the flow rate of the ink ejected from the ejection orifice is larger than the flow rate of the ink circulation flow will be described. The direction of the ink circulation flow in the first communication port 3315a and the first communication port 3315b is directed toward the ejection port 3013. Further, the ink flow rates at the first communication ports 3315a and 3315b tend to be larger than the ink flow rate at the first communication port 3315 a.

Fig. 39A and 39B are graphs showing a relationship between the temperature and the position between the first communication port 3315a and the first communication port 3315B in one ejection port array 3024.

Fig. 39A shows a temperature distribution in the following case as a comparative example: the first communication port 3315a and the first communication port 3315b are arranged at one position in one ejection port row 3024. Since the ink flowing through the first common supply flow path 3313 and the first common recovery flow path 3314 receives heat from the printing element substrate 4010, the temperature of the central portion of the flow path separated from the communication port increases. Further, when the temperatures of the first communication port 3315a and the first communication port 3315b are compared with each other, the temperature of the first communication port 3315a is made low due to a large flow rate of the ink circulation flow.

In addition, even under the condition that ink flows in the first communication ports 3315b not oppositely toward the ejection ports 3013, ink flowing through the flow path and receiving heat from the printing element substrate flows toward the first communication ports 3315 b. Therefore, the temperature near the first communication port 3315a tends to decrease.

Fig. 39B shows the temperature distribution in the following case: the first communication ports 3315a and 3315b are alternately arranged at a plurality of positions in one ejection port row in the present embodiment.

In the present embodiment, the first communication port 3315a and the first communication port 3315b are disposed at a plurality of positions. For this reason, the distance between the first communication ports 3315a and 3315b adjacent to each other is shorter than the comparative example of fig. 39A. Thus, the length of the ink flowing through the first common supply flow path 3313 and the first common recovery flow path 3314 becomes short, and thus the degree of temperature rise of the ink due to heat transferred from the printing element substrate when the ink flows through the flow paths is suppressed to be small. In the present example, in particular, the temperature of the first communicating port 3315b is equal to the temperature of the first communicating port 3315 a.

In the present embodiment, since the first communication ports 3315a and the first communication ports 3315b are alternately arranged with respect to the row direction of the ejection port rows, the maximum length of the ink passing through the first common supply flow path 3313 and the first common recovery flow path 3314 becomes short. Therefore, the degree of temperature increase of the ink caused by heat transferred from the printing element substrate when the ink flows through the flow path is suppressed to be small.

In this way, in the present embodiment, since the first communication ports 3315a and the first communication ports 3315b are alternately arranged at a plurality of positions in one ejection port row, the temperature difference in the printing element substrate 4010 can be reduced as compared with the comparative example shown in fig. 39A. Therefore, since the variation in the ejection characteristics can be suppressed, a high-quality image can be formed with high accuracy.

Fig. 39C shows the temperature distribution of the communication ports in each ejection port array 3024 in the following case: the first communication port 3315a and the first communication port 3315b in the plurality of ejection port arrays 3024 are offset corresponding to the parallelogram shape of the printing element substrate 4010. In the figure, the ejection orifice forming member and the ejection orifice are not shown.

Although the absolute values of the temperatures of the ejection orifice arrays are different from each other depending on the positions of the ejection orifice arrays, it is understood that the high-temperature position and the low-temperature position are shifted from each other in correspondence with a positional shift between the first communication port 3315a and the first communication port 3315b in the array direction of the ejection orifice arrays among the plurality of ejection orifice arrays.

Fig. 39D is a graph showing an average of the temperature distribution of fig. 39C in the arrangement direction of the plurality of ejection port arrays 3024. Since the high-temperature position and the low-temperature position in the ejection orifice arrays are offset from each other, the temperature difference within the printing element substrate 4010 in the averaged state is smaller than that of each of all the ejection orifice arrays of fig. 39C. Thus, when the print medium scanning direction (relative scanning direction between the liquid ejection head and the print medium) is a direction (particularly, a perpendicular direction) intersecting the row direction of the ejection orifice row 3024, the influence of the variation in ejection characteristics due to the temperature difference can be averaged out.

In this way, in the present embodiment, the positions of the first communication port 3315a and the first communication port 3315b in the row direction of the ejection orifice rows are offset from each other between the ejection orifice rows in the plurality of ejection orifice rows. Therefore, the temperature difference caused by the positional relationship between the first communication ports 3315a and 3315b can be uniformly adjusted. Therefore, since the variation in the ejection characteristics can be suppressed, a high-quality image can be formed with high accuracy.

(third embodiment)

Fig. 33A to 33L are diagrams illustrating a liquid ejection head according to a third embodiment of the present invention. The same reference numerals will be given to the same constituent elements as those of the above-described embodiment, and the description thereof will be omitted.

Fig. 33A to 33L are exploded views showing main parts of a liquid ejection head according to an embodiment of the present invention. Fig. 33A to 33F are perspective views. Fig. 33G to 33L are plan views.

In the present embodiment, as shown in fig. 33G and 33H, one first common supply flow path 5313 communicates with the pressure chambers 3023 arranged in the two ejection port arrays 3024. Similarly, the one first common recovery flow path 5314 communicates with the pressure chambers 3023 arranged in the two discharge port arrays 3024. That is, as shown in fig. 33G and 33H, one first common supply channel 5313 or one first common recovery channel 5314 is located between two adjacent rows of the discharge port rows 3024.

In addition to the effects of the first embodiment, the present embodiment is desirable for the following reasons. That is, when the first common supply flow path 5313 and the first common recovery flow path 5314 in two adjacent discharge port rows are shared, the number of partition walls between the flow paths can be reduced. Further, since the flow path resistance is proportional to the square root of the flow path width, when the number N of the ejection ports is the same, it is possible to establish (1) two ejection port rows having a flow path width smaller than the flow path width of the two first common supply flow paths 3313 or the two first common recovery flow paths 3314 of the first embodiment. Further, since the flow resistance R of the first common supply flow path 5313 or the first common recovery flow path 5314 of expression (1) in one ejection port array can be reduced in the case where the intervals of the ejection port arrays are the same, the number N of ejection ports can be increased.

Therefore, compared to the above embodiment, the ejection orifice arrays 3024 can be arranged more densely while further suppressing the pressure change of each pressure chamber or the flow rate change of the ink circulation flow in each pressure chamber. For this reason, the size of the printing element substrate (chip size) can be reduced. Further, in the case where the ejection orifice arrays 3024 are arranged at the same density, the number of the first communication ports 3315a or 3315b can be reduced while further suppressing a pressure change between the pressure chambers or a flow rate change of the ink circulation flow between the pressure chambers. Therefore, the flow path structure of the liquid ejection head can be further simplified.

(fourth embodiment)

Fig. 34A to 34M are diagrams illustrating a liquid ejection head according to a fourth embodiment of the present invention. Here, the same reference numerals will be given to the same constituent elements as those of the above-described embodiment, and the description thereof will be omitted. Fig. 34A to 34M are exploded views showing main parts of a liquid ejection head of an embodiment of the present invention. Fig. 34A to 34G are perspective views. Fig. 34H to 34M are plan views.

As shown in fig. 34A to 34M, in the present embodiment, in order to eject different colors or different kinds of inks, ejection orifices 6051 for a first ink and ejection orifices 6061 for a second ink are arranged in one liquid ejection head. The first flow path member 3050 is provided with a first common supply flow path 6052 for the first ink, a first common supply flow path 6062 for the second ink, a first common recovery flow path 6053 for the first ink, and a first common recovery flow path 6063 for the second ink. Further, the second flow path member 3060 is provided with a first communication port 6054a for the first ink, a first communication port 6064a for the second ink, a first communication port 6054b for the first ink, and a first communication port 6064b for the second ink. Further, the third flow path member 3070 is provided with a second common supply flow path 6056 for the first ink, a second common supply flow path 6066 for the second ink, a second common recovery flow path 6057 for the first ink, and a second common recovery flow path 6067 for the second ink. Further, the fourth flow path member 3080 is provided with a second communication port 6058a for the first ink, a second communication port 6068a for the second ink, a second communication port 6058b for the first ink, and a second communication port 6068b for the second ink. Then, the fifth flow path member 3090 is provided with a third common supply flow path 6070 for the first ink, a third common supply flow path 6080 for the second ink, a third common recovery flow path 6071 for the second ink, and a third common recovery flow path 6081 for the second ink. As for the first ink and the second ink, as in the third embodiment, the inks supplied from the third common supply flow paths 6070 and 6080 pass through the pressure chambers 3024 (flow paths 3310) and flow out of the third common recovery flow paths 6071 and 6081.

Further, as in the third embodiment, one first common supply flow path may communicate with the pressure chambers arranged at the two ejection port arrays. Likewise, one first common recovery flow path may communicate with the pressure chambers arranged at the two discharge port arrays.

Further, the third common supply flow path 6070 and the third common recovery flow path 6071 for the first ink and the third common supply flow path 6080 and the third common recovery flow path 6081 for the second ink may be formed in the following sizes: the sixth flow path layer 3090 is larger than the printing element substrate 3010. That is, the sixth flow path layer 3090 may be formed wide, for example, in a direction intersecting with the row direction of the ejection orifice row 3024 (for example, a direction perpendicular thereto).

Further, as in the present embodiment, when the following configuration is employed in the case of ejecting liquids of different colors from one liquid ejection head, it is possible to reduce the size of the liquid ejection head while suppressing the colors of the liquids from mixing with each other. Specifically, in fig. 34C and 34I, the interval between the first common supply flow path 6052 and the first common collection flow path 6053 that supply the liquids of the same color (the thickness of the wall that separates the two flow paths) can be appropriately smaller than the interval between the flow paths that supply the liquids of different colors (the thickness of the wall that separates the two flow paths). More specifically, the interval between the flow paths of the same color is set smaller than the interval between the first common supply flow path 6052 that supplies the liquid of the first ink and the first common recovery flow path 6053 that recovers the liquid of the second ink and is adjacent to the first common supply flow path 6052.

In this way, even in a liquid ejection head for inks of a plurality of colors or a plurality of inks, it is possible to suppress a pressure change of each pressure chamber and an ink circulation amount change between the pressure chambers without widening the widths of the first common supply flow path and the first common recovery flow path. Therefore, since a decrease in the ejection speed of the liquid droplets or a modulation in the color density due to evaporation of the water in the ejection openings can be suppressed, a high-quality image can be formed with high accuracy.

(fifth embodiment)

Fig. 35A to 35E are perspective views illustrating various liquid ejection heads of the present invention.

Fig. 35A shows an example of a liquid ejection head of the present invention having one printing element substrate. The liquid ejection head prints an image while moving in a reciprocating manner with respect to a printing medium. The fifth flow channel layer 7080 is disposed on the sixth flow channel layer 7090, and the fourth flow channel layer 7070 is disposed on the fifth flow channel layer 7080. Further, the printing element substrate 7010 including the third flow path layer 7060 and the second flow path layer 7050 is disposed on the support member 7030.

Fig. 35B and 35C illustrate an example of a liquid ejection head corresponding to a line head in which a plurality of printing element substrates 7010 are arranged in a zigzag shape. In fig. 35B, each printing element substrate 7010 is disposed on a common support member 7032. Further, in fig. 35C, each printing element substrate 7010 is disposed to each individual supporting member 7034.

Fig. 35D and 35E illustrate an example of a liquid ejection head corresponding to a line head in which a plurality of printing element substrates 7010 are arranged in a row. In fig. 35D, the printing element substrate 7010 is disposed on the common supporting member 7032. Further, in fig. 35E, each printing element substrate 7010 is disposed to each individual supporting member 7034. In this case, the printing element substrate 7010 may have the same shape as the printing element substrate 4010 of the fourth embodiment.

The various liquid ejection heads of the present embodiment can generate the above-described ink circulation flow. Therefore, a pressure change of each pressure chamber or a change in the ink circulation amount between the pressure chambers can be suppressed. Therefore, since a decrease in the ejection speed of the liquid droplets or a modulation in the color density due to evaporation of the water in the ejection openings can be suppressed, a high-quality image can be formed with high accuracy.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.