阅读说明：本技术 液体喷射头 (Liquid ejection head ) 是由 水野泰介 于 2019-09-11 设计创作，主要内容包括：液体喷射头包括由第一行、第二行以及与第一行及第二行连通的流动路径构成的多个组。所述多个组中的每一个组被设置用于彼此不同的多个种类的液体中的相应一种液体。第一行包括多个第一压力室。第二行包括多个第二压力室。第二行位于第一行旁边。流动路径与所述多个第一压力室及所述多个第二压力室连通。流动路径包括多个第一连通通路、多个第二连通通路、多个第三连通通路、多个第四连通通路、第一集管、第二集管和公共集管。(The liquid ejection head includes a plurality of groups of first and second rows and flow paths communicating with the first and second rows. Each of the plurality of groups is provided for a corresponding one of a plurality of kinds of liquids different from each other. The first row includes a plurality of first pressure chambers. The second row includes a plurality of second pressure chambers. The second row is located next to the first row. A flow path communicates with the plurality of first pressure chambers and the plurality of second pressure chambers. The flow path includes a plurality of first communication passages, a plurality of second communication passages, a plurality of third communication passages, a plurality of fourth communication passages, a first header, a second header, and a common header.)

1. A liquid ejection head comprising:

a plurality of groups constituted by a first row, a second row, and flow paths communicating with the first row and the second row, each of the plurality of groups being provided for a corresponding one of a plurality of kinds of liquids different from each other; wherein:

the first row includes a plurality of first pressure chambers aligned in a line in an alignment direction;

the second row includes a plurality of second pressure chambers aligned in the alignment direction, the second row being located beside the first row in a width direction perpendicular to the alignment direction; and is

The flow path is in communication with the plurality of first pressure chambers and the plurality of second pressure chambers, the flow path including:

a plurality of first communication passages, each of which communicates with each of the first pressure chambers at a position close to the second row in the width direction;

a plurality of second communication passages, each of which communicates with each of the first pressure chambers at a position distant from the second row in the width direction;

a plurality of third communication passages, each of which communicates with each of the second pressure chambers at a position close to the first row in the width direction;

a plurality of fourth communication passages, each of which communicates with each of the second pressure chambers at a position distant from the first row in the width direction;

a first header that communicates with the plurality of first pressure chambers through the plurality of second communication passages;

a second header communicating with the plurality of second pressure chambers through the plurality of fourth communication passages; and

a common header located between the first header and the second header in the width direction, the common header communicating with the plurality of first pressure chambers through the plurality of first communication passages, and the common header communicating with the plurality of second pressure chambers through the plurality of third communication passages.

2. The liquid ejection head according to claim 1, wherein the first header, the second header, and the common header extend in the arrangement direction, and a sectional area of the common header taken along a plane perpendicular to the arrangement direction is larger than a sectional area of the first header taken along the plane and a sectional area of the second header taken along the plane.

3. The liquid ejection head according to claim 2, wherein the sectional area of the common header is at least 1.6 times larger than the sectional area of the first header and the sectional area of the second header.

4. The liquid ejection head according to claim 1, wherein a length of the first manifold in the arrangement direction is equal to a length of the second manifold in the arrangement direction.

5. The liquid ejection head according to claim 4, wherein the first manifold is at a position different from a position of the second manifold in the arrangement direction.

6. The liquid ejection head according to claim 1, wherein a length of the common header in the arrangement direction is smaller than a length of the first header in the arrangement direction and a length of the second header in the arrangement direction.

7. The liquid ejection head according to claim 1,

wherein the first header is a return header into which the liquid can flow from the plurality of first pressure chambers through the plurality of second communication passages;

wherein the second header is a return header into which the liquid can flow from the plurality of second pressure chambers through the plurality of fourth communication passages;

wherein the common header is a supply header from which the liquid is able to flow into the plurality of first pressure chambers through the plurality of first communication passages and into the plurality of second pressure chambers through the plurality of third communication passages.

8. The liquid ejection head according to claim 1, wherein the plurality of groups comprise:

a first set through which a first liquid is configured to flow, the first set providing a first circulation path comprising the first row, the second row, and the flow path; and

a second group through which a second liquid different from the first liquid is configured to flow, the second group providing a second circulation path that is independent of the first circulation path, the second circulation path including the first row, the second row, and the flow path, the first row, the second row, and the flow path of the second circulation path being different from the first row, the second row, and the flow path of the first group, respectively;

wherein the second row of the first set and the first row of the second set are positioned adjacent to each other;

wherein in the first group, the first group is selected,

the first header is a return header into which the first liquid can flow from the plurality of first pressure chambers through the plurality of second communication passages;

the second header is a return header into which the first liquid can flow from the plurality of second pressure chambers through the plurality of fourth communication passages; and is

The common header is a supply header from which the first liquid is able to flow into the plurality of first pressure chambers through the plurality of first communication passages and into the plurality of second pressure chambers through the plurality of third communication passages;

wherein in the second set of the plurality of sets,

the first header is a supply header from which the second liquid is able to flow into the plurality of first pressure chambers through the plurality of second communication passages;

the second header is a supply header from which the second liquid can flow into the plurality of second pressure chambers through the plurality of fourth communication passages;

the common header is a return header into which the second liquid is able to flow from the plurality of first pressure chambers through the plurality of first communication passages and from the plurality of second pressure chambers through the plurality of third communication passages.

9. The liquid ejection head according to claim 1, wherein the flow path further comprises an engaging passage, the engaging passage being connected to the first manifold and the second manifold.

10. The liquid ejection head according to claim 9, wherein the joint passage overlaps the first header in a stacking direction that is perpendicular to the arrangement direction and the width direction at a position opposite to the second communication passage with respect to the first header, and the joint passage also overlaps the second header in the stacking direction at a position opposite to the fourth communication passage with respect to the second header.

11. The liquid ejection head according to claim 9, wherein the engagement passage has one end and another end in a length direction of the engagement passage, the one end being at a position other than a position farther from the fourth communication passage than the second communication passage, and the another end being at a position other than a position farther from the second communication passage than the fourth communication passage than the second communication passage.

12. The liquid ejection head according to claim 9, wherein the first manifold has an end in the arrangement direction, and the second manifold has an end in the arrangement direction;

wherein the joining passage is connected to the end of the first header and the end of the second header.

13. The liquid ejection head according to claim 9, wherein the first header and the second header have downstream end portions in a flow direction of the liquid flowing through the first header and the second header, the joint passage being connected to the downstream end portions.

14. The liquid ejection head according to claim 9, wherein the engagement passage extends in a length direction thereof, the length direction and the arrangement direction defining an angle therebetween that is greater than zero and less than 90 degrees.

15. The liquid ejection head according to claim 9, wherein the flow path further comprises:

a first reservoir passage connected to a tank of the liquid;

a first connection passage through which the engagement passage is connected to the first reservoir passage;

a second reservoir passage connected to the tank; and

a second connection passage through which the second reservoir passage is connected to the common header.

16. The liquid ejection head according to claim 15, wherein the first connection passage extends from the junction passage toward the first reservoir passage in a direction away from a center in the width direction of an arrangement of the plurality of the first headers and the second headers.

17. The liquid ejection head according to claim 15, wherein the engagement passage has one end portion and another end portion in a length direction, the one end portion being connected to the first manifold, and the other end portion being connected to the second manifold;

wherein the first connecting passage is connected to a central portion of the engaging passage between the one end portion and the other end portion in the length direction.

18. The liquid ejection head according to claim 15, wherein the first header, the second header, and the common header have end portions and an intermediate portion in the arrangement direction;

wherein the engagement passage comprises:

an end joining passage through which the end of the first header and the end of the second header are connected together; and

an intermediate joining passage through which the intermediate portion of the first header and the intermediate portion of the second header are connected together;

wherein the first connection path includes:

a first end connection passage through which the end engagement passage is connected to the first reservoir passage; and

a first intermediate connection passage through which the intermediate junction passage is connected to the first reservoir passage;

wherein the second connection path includes:

a second end connection passage through which the end portion of the common header is connected to the second reservoir passage; and

a second intermediate connection passage through which the intermediate portion of the common header is connected to the second reservoir passage.

19. The liquid ejection head according to claim 18, wherein the first intermediate connection passage extends from the intermediate junction passage toward the first reservoir passage in a direction away from a center in the width direction of an arrangement of the plurality of the first headers and the second headers;

wherein the second intermediate connection passage extends from the common header toward the second reservoir passage in a direction away from the center in the width direction of the arrangement of the plurality of first headers and the second header.

20. The liquid ejection head according to claim 18, wherein the end joint passage is connected to each end of the first header in the arrangement direction and to each end of the second header in the arrangement direction, thereby providing a pair of end joint passages;

wherein said first end connection passageway is connected to each end engagement passageway, thereby providing a pair of said first end connection passageways, each end of each first end connection passageway providing a pair of ends directly connected to said first reservoir passageway;

wherein one end of said first intermediate connecting passage is directly connected to said first reservoir passage, said pair of ends of said first end connecting passage and said one end of said first intermediate connecting passage being aligned with each other in said alignment direction;

wherein the second end connection passageway is connected to each end of the common header in the arrangement direction, thereby providing a pair of second end connection passageways, one end of each second end connection passageway being directly connected to the second reservoir passageway, thereby providing an opposite end of the second end connection passageway;

wherein one end of said second intermediate connecting passage is directly connected to said second reservoir passage, said pair of ends of said second end engagement passage and said one end of said second intermediate connecting passage are aligned with each other in said alignment direction.

21. A liquid ejection head comprising:

a first plate formed with a first header according to claim 1, a second header according to claim 1, and a common header according to claim 1;

a damping plate that is laminated on the first plate and is elastically deformable; and

a second plate laminated on the damper plate, the second plate having a surface facing the damper plate, the surface being formed with damper grooves, one of the damper grooves being positioned in an overlapping relationship with the first header, another of the damper grooves being positioned in an overlapping relationship with the second header, and yet another of the damper grooves being positioned in an overlapping relationship with the common header, in a lamination direction perpendicular to the arrangement direction and the width direction.

Technical Field

The present disclosure relates to a liquid ejection head.

Background

Japanese patent application publication 2013-67178 discloses an ink jet head. The ink-jet head includes a head plate at which two rows of a plurality of pressure chambers, an ink discharge passage, and a pair of ink supply passages are formed. An ink discharge passage is formed between the two rows of the plurality of pressure chambers. The two rows of pressure chambers and the ink discharge passage are located between the pair of ink supply passages. The ink supply passage is connected to the tank through an inlet pipe, and the ink discharge passage is connected to the tank through an outlet pipe.

The pressure chamber described in japanese patent application publication 2013-67178 is configured to allow a single kind of liquid to flow therethrough. The publication does not disclose a pressure chamber allowing a plurality of kinds of liquids to flow therethrough. Therefore, the generalization of the inlet pipes of the pressure chambers each in fluid communication with each of the plurality of kinds of liquids may result in the mixing of the plurality of kinds of liquids.

Disclosure of Invention

In view of the above, an object of the present disclosure is to provide a liquid ejection head capable of avoiding color mixing of liquid.

To achieve the above and other objects, according to one aspect, the present disclosure provides a liquid ejection head comprising: a plurality of sets of a first row, a second row, and a flow path in communication with the first row and the second row. Each of the plurality of groups is provided for a corresponding one of a plurality of kinds of liquids different from each other. The first row includes a plurality of first pressure chambers aligned in a line in an alignment direction. The second row includes a plurality of second pressure chambers aligned in the alignment direction. The second row is located beside the first row in a width direction perpendicular to the arrangement direction. The flow path communicates with the plurality of first pressure chambers and the plurality of second pressure chambers. The flow path includes a plurality of first communication passages, a plurality of second communication passages, a plurality of third communication passages, a plurality of fourth communication passages, a first header, a second header, and a common header. The plurality of first communication passages each communicate with each of the first pressure chambers at a position close to the second row in the width direction. The plurality of second communication passages each communicate with each of the first pressure chambers at a position distant from the second row in the width direction. Each of the plurality of third communication passages communicates with each of the second pressure chambers at a position close to the first row in the width direction. Each of the plurality of fourth communication passages communicates with each of the second pressure chambers at a position distant from the first row in the width direction. The first header communicates with the plurality of first pressure chambers through the plurality of second communication passages. The second header communicates with the plurality of second pressure chambers through the plurality of fourth communication passages. The common header is located between the first header and the second header in the width direction, and the common header communicates with the plurality of first pressure chambers through the plurality of first communication passages, and the common header communicates with the plurality of second pressure chambers through the plurality of third communication passages.

Preferably, the first header, the second header, and the common header extend in the arrangement direction. The common header has a cross-sectional area taken along a plane perpendicular to the arrangement direction that is larger than a cross-sectional area taken along the plane of the first header and a cross-sectional area taken along the plane of the second header.

Preferably, the cross-sectional area of the common header is at least 1.6 times greater than the cross-sectional area of the first header and the cross-sectional area of the second header.

Preferably, the length of the first header in the arrangement direction is equal to the length of the second header in the arrangement direction.

Preferably, the first header is at a position different from a position of the second header in the arrangement direction.

Preferably, the length of the common header in the arrangement direction is smaller than the length of the first header in the arrangement direction and the length of the second header in the arrangement direction.

Preferably, the first header is a return header into which the liquid can flow from the plurality of first pressure chambers through the plurality of second communication passages. The second header is a return header into which the liquid can flow from the plurality of second pressure chambers through the plurality of fourth communication passages. The common header is a supply header from which the liquid can flow into the plurality of first pressure chambers through the plurality of first communication passages and into the plurality of second pressure chambers through the plurality of third communication passages.

Preferably, the plurality of sets includes a first set through which a first liquid is configured to flow and a second set through which a second liquid different from the first liquid is configured to flow. The first group provides a first circulation path including the first row, the second row, and the flow path. The second set provides a second circulation path that is independent of the first circulation path. The second circulation path includes the first row, the second row, and the flow path, the first row, the second row, and the flow path of the second circulation path being different from the first row, the second row, and the flow path of the first group, respectively. The second row of the first set and the first row of the second set are located adjacent to each other. In the first group, the first header is a return header into which the first liquid can flow from the plurality of first pressure chambers through the plurality of second communication passages; the second header is a return header into which the first liquid can flow from the plurality of second pressure chambers through the plurality of fourth communication passages; and the common header is a supply header from which the first liquid is able to flow into the plurality of first pressure chambers through the plurality of first communication passages and into the plurality of second pressure chambers through the plurality of third communication passages. In the second group, the first header is a supply header, and the second liquid is able to flow from the supply header into the plurality of first pressure chambers through the plurality of second communication passages; the second header is a supply header from which the second liquid can flow into the plurality of second pressure chambers through the plurality of fourth communication passages; the common header is a return header into which the second liquid is able to flow from the plurality of first pressure chambers through the plurality of first communication passages and from the plurality of second pressure chambers through the plurality of third communication passages.

Preferably, the flow path further comprises a junction passage connected to the first header and the second header.

Preferably, the joint passage overlaps with the first header in a stacking direction perpendicular to the arrangement direction and the width direction at a position opposite to the second communication passage with respect to the first header, and the joint passage also overlaps with the second header in the stacking direction at a position opposite to the fourth communication passage with respect to the second header.

Preferably, the engagement passage has one end and the other end in a length direction of the engagement passage, the one end being at a position other than a position farther from the fourth communication passage than the second communication passage, and the other end being at a position other than a position farther from the second communication passage than the fourth communication passage.

Preferably, the first header has an end in the arrangement direction, and the second header has an end in the arrangement direction. The junction passage is connected to the end of the first header and the end of the second header.

Preferably, the first header and the second header have downstream ends in a flow direction of the liquid flowing through the first header and the second header, the junction passage being connected to the downstream ends.

Preferably, the engagement passage extends in a length direction thereof, the length direction and the arrangement direction defining an angle therebetween that is greater than zero and less than 90 degrees.

Preferably, the flow path further comprises: a first reservoir passage connected to a tank of the liquid; a first connection passage through which the engagement passage is connected to the first reservoir passage; a second reservoir passage connected to the tank; and a second connection passage through which the second reservoir passage is connected to the common header.

Preferably, the first connection passage extends from the junction passage toward the first reservoir passage in a direction away from a center in the width direction of an arrangement of the plurality of first headers and the second header.

Preferably, the engaging passage has one end portion and the other end portion in the length direction, the one end portion being connected to the first header, and the other end portion being connected to the second header. The first connection passage is connected to a central portion of the engagement passage between the one end portion and the other end portion in the length direction.

Preferably, the first header, the second header, and the common header have end portions and an intermediate portion in the arrangement direction. The engagement passage includes: an end joining passage through which the end of the first header and the end of the second header are connected together; and an intermediate joining passage through which the intermediate portion of the first header and the intermediate portion of the second header are connected together. The first connection path includes: a first end connection passage through which the end engagement passage is connected to the first reservoir passage; and a first intermediate connection passage through which the intermediate junction passage is connected to the first reservoir passage. The second connection path includes: a second end connection passage through which the end portion of the common header is connected to the second reservoir passage; and a second intermediate connection passage through which the intermediate portion of the common header is connected to the second reservoir passage.

Preferably, the first intermediate connection passage extends from the intermediate junction passage toward the first reservoir passage in a direction away from a center in the width direction of an arrangement of the plurality of first headers and the second header. The second intermediate connection passage extends from the common header toward the second reservoir passage in a direction away from the center in the width direction of the arrangement of the plurality of first headers and the second header.

Preferably, the end joining passage is connected to each end of the first header in the arrangement direction and to each end of the second header in the arrangement direction, thereby providing a pair of end joining passages. The first end connection passage is connected to each of the end joining passages, thereby providing a pair of the first end connection passages. Each end of each first end connection path provides a pair of ends that are directly connected to the first reservoir path. One end of the first intermediate connection passage is directly connected to the first reservoir passage. The pair of ends of the first end connecting passage and the one end of the first intermediate connecting passage are aligned with each other in the arrangement direction. The second end connection passage is connected to each end of the common header in the arrangement direction, thereby providing a pair of second end connection passages. One end of each second end connection passageway is directly connected to the second reservoir passageway, thereby providing a pair of ends of the second end connection passageway. One end of the second intermediate connection passage is directly connected to the second reservoir passage. The pair of ends of the second end engagement passage and the one end of the second intermediate connecting passage are aligned with each other in the array direction.

According to another aspect, the present disclosure provides a liquid ejection head including a first plate, a damping plate, and a second plate. The first plate is formed with the first header, the second header, and the common header. The damping plate is laminated on the first plate, and the damping plate is elastically deformable. The second plate is laminated on the damping plate. The second plate has a surface facing the damping plate. The surface is formed with a damping groove. One of the dampening grooves is positioned in overlapping relation with the first header. Another of the damper grooves is positioned in overlapping relation with the second header. Still another one of the damper grooves is positioned in an overlapping relationship with the common header in a stacking direction perpendicular to the arrangement direction and the width direction.

Drawings

The particular features and advantages of the embodiments, as well as other objects, will become apparent from the following description when taken in conjunction with the accompanying drawings, wherein:

fig. 1 is a schematic view of a liquid ejection apparatus provided with a head according to a first embodiment;

FIG. 2 is a plan view of the head, and particularly shows the ejection surface of the head;

FIG. 3 is an enlarged cross-sectional view of the head taken along line A-A in FIG. 2;

FIG. 4 is an exploded perspective view of a head according to a second embodiment;

FIG. 5 is an enlarged cross-sectional view of a head according to a second embodiment taken along a line corresponding to line A-A in FIG. 2;

fig. 6A is a perspective view of a second plate in the head according to the third embodiment, viewed from above in the stacking direction;

fig. 6B is a perspective view of the second plate in the head according to the third embodiment, viewed from below in the stacking direction;

FIG. 7 is an enlarged cross-sectional view of a head according to a third embodiment taken along a line corresponding to line A-A in FIG. 2;

FIG. 8 is an exploded perspective view of a head according to a fourth embodiment;

fig. 9 is a perspective view showing a second plate, a first connecting plate, a second connecting plate, and a third connecting plate in the head according to the fourth embodiment as viewed from above in the stacking direction;

fig. 10 is a perspective view showing a second plate, a first connecting plate, a second connecting plate, and a third connecting plate in the head according to the fourth embodiment as viewed from below in the stacking direction; and is

Fig. 11 is a perspective view showing the second plate, the first connecting plate, the second connecting plate, and the third connecting plate in the head according to the fifth embodiment as viewed from above in the stacking direction.

Detailed Description

[ first embodiment ]

A liquid ejection head 11 according to a first embodiment will be described with reference to fig. 1 to 3. The liquid ejection head 11 is provided in a liquid ejection apparatus 10 such as an ink jet printer.

[ Structure of liquid ejecting apparatus ]

The liquid ejecting apparatus 10 includes a platen 12, a transport mechanism 13, and a line head 14. The platen 12 is a support on which the sheet 15 can be mounted. The conveying mechanism 13 includes a pair of conveying rollers 13a, 13 a. The platen 12 is located between a pair of conveying rollers 13a and 13a in the conveying direction, so that the sheet 15 is conveyed by the pair of conveying rollers 13a, 13a in the conveying direction.

The line head 14 extends in the longitudinal direction by a length greater than the length in the width direction of the sheet 15. The longitudinal direction is perpendicular to the conveying direction, and is an example of a "vertical direction". The line head 14 includes a plurality of heads 11. The head 11 includes an ejection plate 20, and an ejection surface 21 of the ejection plate 20 is formed with a plurality of ejection ports 22, the plurality of ejection ports 22 being aligned with each other in an alignment direction. Details of the head 11 will be described in detail. Further, the arrangement direction is perpendicular to the conveying direction. In this case, the arrangement direction is the same as the vertical direction. Alternatively, the arrangement direction may intersect the conveyance direction.

Each injection port 22 is fluidly connected to the canister 16. Tank 16 includes a subtank 16a and a storage tank 16b, subtank 16a being located on line head 14, and storage tank 16b being connected to subtank 16a through a pipe 17. The liquid is stored in the sub tank 16a and the storage tank 16 b. The number of tanks 16 corresponds to the number of colors of the liquid ejected from the ejection openings 22. For example, four tanks 16 are provided for four colors of black, yellow, cyan, and magenta. Therefore, the line head 14 is configured to eject a plurality of kinds of liquids.

The line head 14 is movable but fixed at one position, and the line head 14 is configured to: the line head 14 ejects liquid from the plurality of ejection openings 22 while the sheet 15 is moved in the conveyance direction by the conveyance mechanism 13. Thus, an image is formed on the sheet 15. A serial head that can move in the vertical direction may be used instead of the line head 14.

[ Structure of head ]

The longitudinal direction of the head 11 corresponds to the "vertical direction" and the "arrangement direction", and the line head 11 also defines a width direction perpendicular to the longitudinal direction, and the width direction corresponds to the conveyance direction. As shown in fig. 2 and 3, the head 11 includes an ejection plate 20, a pressure chamber plate 30, a vibration plate 40, a containing plate 50, and a first plate 60. Each of the plates is in the shape of a rectangular flat plate and is made of silicon, resin, or metal.

The plates are successively laminated in the above-described order, and adjacent plates are joined together by an adhesive. The stacking direction (lamination direction) is perpendicular to the alignment direction and the width direction, and the width direction is perpendicular to the alignment direction. In the following description, the terms "above" and "below" are used so that the ejection plate 20 is located below the pressure chamber plate 30, and the pressure chamber plate 30 is located above the ejection plate 20. However, the orientation of the head 11 is not limited to this orientation.

The spray plate 20 is formed with a plurality of nozzles 23, the plurality of nozzles 23 extending through the thickness of the spray plate 20 in the stacking direction. The spray plate 20 has a lower surface which serves as a spray surface 21 where the nozzles 23 are open. The nozzle 23 has an open end as the ejection port 22.

The plurality of ejection openings 22 are arranged one after another in the arrangement direction to form an ejection opening row 24. Eight ejection port rows 24 are arranged in the width direction. A pair of ejection openings 24 adjacent in the width direction corresponds to one color of liquid, and therefore, four pairs of adjacent ejection openings 24 correspond to four colors of liquid, for example, black, yellow, cyan, and magenta, respectively.

The pressure chamber plate 30 is formed with a plurality of pressure chambers 31. Each pressure chamber 31 communicates with each nozzle 23. The pressure chamber 31 is part of a separate channel and each separate channel communicates with each nozzle 23.

The pressure chamber 31 is defined by a through hole formed in the pressure chamber plate 30 in the stacking direction and communicating with the nozzle 23. The through hole has a lower end covered by the injection plate 20. The pressure chamber 31 is a rectangular parallelepiped, and the longitudinal direction thereof coincides with the width direction. Each nozzle 23 is located at the center in the width direction of each pressure chamber 31.

The plurality of pressure chambers 31 are sequentially arranged in line in the arrangement direction to form a pressure chamber row 32. A plurality of pressure chamber rows 32 (eight pressure chamber rows 32 in this embodiment) extend parallel to each other and are arranged in the width direction. A pair of pressure chamber rows 32 adjacent in the width direction (e.g., a first pressure chamber row 32a and a second pressure chamber row 32b) are connected to the same tank 16 (fig. 1).

The vibration plate 40 is positioned opposite to the ejection plate 20 with respect to the pressure chamber 31. The vibration plate 40 includes an elastic film 41 and an insulating film 42. The elastic membrane 41 is located on the upper surface of the pressure chamber plate 30, and is capable of being elastically deformed in the stacking direction. The insulating film 42 covers the upper surface of the elastic film 41, and is made of an electrically insulating material. The vibration plate 40 is formed with a plurality of pairs of communication passages 43, and each pair of communication passages 43 communicates with each pressure chamber 31.

The receiving plate 50 is positioned opposite to the pressure chamber plate 30 with respect to the vibration plate 40. That is, the accommodating plate 50 is located on the upper surface of the insulating film 42. The accommodation plate 50 is formed with a plurality of pairs of communication passages, each pair communicating with each pair of communication passages 43. The receiving plate 50 is also formed with a plurality of receiving spaces 55.

The plurality of pairs of communication passages include a first pair of first and second communication passages 51 and 52 for the first pressure chamber 31a and a second pair of third and fourth communication passages 53 and 54 for the second pressure chamber 31 b. That is, two pairs of communicating paths are provided for each color. According to the present embodiment, sixteen communication passages are formed in one head 11. Therefore, four sets of two pairs of communication passages are provided for four colors.

Each communication passage extends through the accommodation plate 50 in the stacking direction, and communicates with each pressure chamber 31 through each communication passage 43 of the vibration plate 40. The pair of first and second communication passages 51, 52 are fluidly connected to the first pressure chambers 31a constituting the first pressure chamber row 32a, and the pair of third and fourth communication passages 53, 54 are fluidly connected to the second pressure chambers 31b constituting the second pressure chamber row 32 b. Therefore, each pair of communication passages is provided for each pressure chamber 31.

The accommodation space 55 is located between the first communication passage 51 and the second communication passage 52 in the width direction, and the other accommodation space 55 is located between the third communication passage 53 and the fourth communication passage 54 in the width direction. Further, in the width direction, the first communication passage 51 and the third communication passage 53 are positioned close to each other and between the second communication passage 52 and the fourth communication passage 54.

Therefore, the first communication passage 51 communicates with the first pressure chamber 31a at a position close to the second pressure chamber row 32b, and the second communication passage 52 communicates with the first pressure chamber 31a at a position farther from the second pressure chamber row 32b than the first communication passage 51 from the second pressure chamber row 32 b. Further, the third communication passage 53 communicates with the second pressure chamber 31b at a position close to the first pressure chamber row 32a, and the fourth communication passage 54 communicates with the second pressure chamber 31b at a position farther from the first pressure chamber row 32a than the third communication passage 53 from the first pressure chamber row 32 a.

The accommodation space 55 provides an inner space of the accommodation plate 50, and the accommodation space 55 is upwardly recessed from a lower surface of the accommodation plate 50. The accommodation space 55 is, for example, a rectangular parallelepiped shape, and is elongated in the arrangement direction. The plurality of accommodating spaces 55 are arrayed in the array direction, and a piezoelectric element 56 is accommodated in each accommodating space 55.

Each piezoelectric element 56 is located on the vibration plate 40 at a position overlapping each pressure chamber 31 in the stacking direction. The piezoelectric element 56 includes a common electrode 57, a piezoelectric body 58, and a discrete electrode 59, and the common electrode 57, the piezoelectric body 58, and the discrete electrode 59 are laminated in this order. The common electrode 57 is shared by the plurality of piezoelectric elements 56, and is laminated on the upper surface of the vibration plate 40 so as to completely cover a portion of the vibration plate 40, which defines each pressure chamber 31. The common electrode 57 extends over the first pressure chamber row 32 a. A piezoelectric body 58 and a discrete electrode 59 are provided for each pressure chamber 31, and the piezoelectric body 58 and the discrete electrode 59 are located above the pressure chamber 31.

When a voltage is applied to the discrete electrodes 59, the piezoelectric bodies 58 are deformed, so that the vibration plate 40 is displaced in the stacking direction. Due to the displacement of the vibration plate 40 toward the pressure chamber 31, the internal volume of the pressure chamber 31 is reduced to apply pressure to the liquid in the pressure chamber 31, thereby ejecting the liquid through the nozzle 23 communicating with the pressure chamber 31.

A plurality of headers including a first header 61, a second header 62, and a common header 63 are formed in the first plate 60. These headers 61, 62, 63 extend through the first plate 60 in the stacking direction. Each lower end of each of the headers 61, 62, 63 is covered by the upper surface of the receiving plate 50.

Each of the headers 61, 62, 63 is elongated in the arrangement direction, and each of the headers is parallel to each other with a space between adjacent headers in the width direction. The common header 63 is located between the first header 61 and the second header 62 in the width direction. These headers 61, 62, 63 provide a longitudinal direction as an arrangement direction.

The first header 61 communicates with the plurality of first pressure chambers 31a constituting the first pressure chamber row 32a through the plurality of second communication passages 52. The second header 62 communicates with the plurality of second pressure chambers 31b constituting the second pressure chamber row 32b through the plurality of fourth communication passages 54. The common header 63 communicates with the plurality of first pressure chambers 31a constituting the first pressure chamber row 32a through the plurality of first communication passages 51, and the common header 63 communicates with the plurality of second pressure chambers 31b constituting the second pressure chamber row 32b through the plurality of third communication passages 53.

In the present embodiment, four pairs of the first pressure chamber row 32a and the second pressure chamber row 32b are provided in one head 11, and four sets of headers (each set of headers includes a first header 61, a second header 62, and a common header 63) are provided accordingly. Each set of headers 61, 62, 63 is connected to the same sub-tank 16 a. Therefore, the flow path 33 connected to the same sub-tank 16a includes a first communication passage communicating with the first pressure chamber 31a and a second communication passage communicating with the second pressure chamber 31 b.

Specifically, the first communication passage includes a common header 63, a first communication passage 51, a second communication passage 52, and a first header 61, and is fluidly connected to the first pressure chamber 31a such that the liquid flows in the order of the common header 63, the first communication passage 51, the first pressure chamber 31a, the second communication passage 52, and the first header 61. Further, the second communication passage includes a common header 63, a third communication passage 53, a fourth communication passage 54, and a second header 62, and is fluidly connected to the second pressure chamber 31b such that the liquid flows in the order of the common header 63, the third communication passage 53, the second pressure chamber 31b, the fourth communication passage 54, and the second header 62.

The common header 63 is common to the first communication passage and the second communication passage of the flow path 33. In other words, the first communication passage 51 and the third communication passage 53 branch off from the common header 63. A liquid circulation path including the flow path 33, the first pressure chamber 31a, and the second pressure chamber 31b is connected to the sub-tank 16 a. Specifically, the circulation path includes: a first circulation passage for circulating the liquid through the sub-tank 16a, the first communication passage, and the first pressure chamber 31 a; and a second circulation passage for circulating the liquid through the sub-tank 16a, the second communication passage, and the second pressure chamber 31 b.

More specifically, as shown in fig. 2, the head 11 is formed with a plurality of (four in this embodiment) liquid circulation paths including a first liquid circulation path 34a, a second liquid circulation path 34b, a third liquid circulation path 34c, and a fourth liquid circulation path 34d for four kinds of liquids. That is, the first liquid flows through the first liquid circulation path 34a, the second liquid flows through the second liquid circulation path 34b, the third liquid flows through the third liquid circulation path 34c, and the fourth liquid flows through the fourth liquid circulation path 34 d.

The tank 16 is provided for each of the liquid circulation paths 34a to 34d, and each liquid circulation path is connected to each tank 16 independently of each other. Each liquid circulation path includes a first header 61, a second header 62, and a common header 63. The first header 61, the common header 63, and the second header 62 of the first liquid circulation path 34a and the first header 61, the common header 63, and the second header 62 of the second liquid circulation path 34b are parallel to each other and arranged in the width direction in the above-described order.

Therefore, the second header 62 of the first liquid circulation path 34a and the first header 61 of the second liquid circulation path 34b extend in parallel with each other and are positioned side by side. Incidentally, the description of the third liquid circulation path 34c and the fourth liquid circulation path 34d will be omitted because the third liquid circulation path 34c and the fourth liquid circulation path 34d have the same structure or layout as the first liquid circulation path 34a and the second liquid circulation path 34 b.

In the liquid circulation passage, the first header 61 serves as a return header for returning the liquid from the first pressure chamber 31a to the sub-tank 16 through the second communication passage 52, and the second header 62 serves as a return header for returning the liquid from the second pressure chamber 31b to the sub-tank 16 through the fourth communication passage 54.

Further, the common header 63 serves as a supply header for supplying the liquid from the sub-tank 16 to the first pressure chamber 31a through the first communication passage 51 and to the second pressure chamber 31b through the third communication passage 53. Therefore, the common header 63 located between the first pressure chamber row 32a and the second pressure chamber row 32b in the width direction is common to the first pressure chamber row 32a of the first pressure chambers 31a and the second pressure chamber row 32b of the second pressure chambers 31 b. Therefore, the dimension of the common header 63 in the width direction can be set small.

Here, the inflow of liquid from the first pressure chamber 31a and the second pressure chamber 31b into the first header 61 and the second header 62 can suppress an increase in the size of bubbles contained in the liquid, as compared with the inflow of liquid from the first pressure chamber 31a and the second pressure chamber 31b into the single common header 63.

In the head 11, a liquid circulation passage including a first pressure chamber 31a, a second pressure chamber 31b, and a flow path 33 is provided for each sub-tank 16a, that is, for each liquid. The plurality of liquid circulation paths are independent from each other so that mixing of liquids does not occur between a liquid flowing through one liquid circulation path and a liquid flowing through another liquid circulation path, thereby avoiding mixing of colors.

As shown in fig. 3, in the flow path 33, the common header 63 has a larger sectional area than each of the sectional areas of the first header 61 and the second header 62 taken along a plane perpendicular to the longitudinal direction thereof.

In the flow path 33, a first header 61 and a second header 62 are provided with respect to one common header 63. Therefore, the amount of liquid flowing through each of the first header 61 and the second header 62 is half of the amount of liquid flowing through the common header 63. With this structure, the first header 61 and the second header 62 can have a size smaller than that of the common header 63, thereby making the head 11 compact.

The sectional area of the common header 63 is 1.6 times as large as the sectional area of the first header 61 and the sectional area of the second header 62. Therefore, the amount of liquid flowing through the common header 63 is larger than the amount of liquid flowing through each of the first header 61 and the second header 62. Here, the passage resistance in the common header 63 can be equal to or approximately equal to the passage resistance in the first header 61 and the second header 62. Accordingly, a smooth flow of the liquid is achieved in the flow path 33.

Further, the first header 61 has a length in the arrangement direction equal to that of the second header 62. Here, as long as the sectional area of the first header 61 is equal to that of the second header 62, the amount of liquid flowing through the first header 61 is equal to that of the second header 62.

Incidentally, the common header 63 may serve as a return header, and the first header 61 and the second header 62 may serve as supply headers. In this case, the first communication passage 51 and the third communication passage 53 are return passages, and the second communication passage 52 and the fourth communication passage 54 are supply passages.

[ modification of the first embodiment ]

According to the first embodiment, in all of the plurality of liquid-circulation paths, all of the first headers 61 and the second headers 62 are return headers, and all of the common headers 63 are supply headers, or all of the first headers 61 and the second headers 62 are supply headers, and all of the common headers 63 are return headers. In contrast, as a variation, the supply header may be replaced with a return header for each of the plurality of liquid circulation paths, and vice versa.

For example, according to the first embodiment, the first header 61 and the second header 62 of the first liquid circulation path 34a are return headers, and the first header 61 and the second header 62 of the second liquid circulation path 34b are also return headers. On the other hand, according to the modification, the first header 61 and the second header 62 of the first liquid circulation path 34a are return headers, and the first header 61 and the second header 62 of the second liquid circulation path 34b are supply headers. Therefore, in this modification, the first liquid flows from the second pressure chamber row 32b to the sub-tank 16a through the second header 62 of the first liquid circulation path 34a, and the second liquid flows from the sub-tank 16a to the first pressure chamber row 32a through the first header 61 of the second liquid circulation path 34 b.

Here, a heater (not shown) for heating the liquid to be supplied to each pressure chamber is provided at each sub-tank 16a or at a position between the sub-tank 16a and each header. In the first liquid circulation path 34a, the heated liquid flows through the common header 63, and then flows through the first header 61 and the second header 62. On the other hand, in the second liquid circulation path 34b, the heated liquid flows through the first header 61 and the second header 62, and then flows through the common header 63.

The temperature of the liquid decreases toward the downstream of the circulation passage. Therefore, the temperature of the second liquid flowing through the first header 61 of the second liquid circulation path 34b is higher than the temperature of the first liquid flowing through the second header 62 of the first liquid circulation path 34 a. In this way, since the temperatures of the liquids flowing through the adjacent headers 61 and 62 are different from each other, heat exchange occurs between the adjacent liquids, thereby uniformizing the temperatures of the liquids.

[ second embodiment ]

A head 111 according to a second embodiment will be described with reference to fig. 4 and 5, in which like parts and components are denoted by like reference numerals as shown in the first embodiment, to avoid repetitive description. The head 111 further includes a damping plate 64 and a second plate 70.

The damping plate 64 is laminated on the upper surface of the first plate 60, and the second plate 70 is laminated on the upper surface of the damping plate 64. The plates are bonded together by an adhesive. Alternatively, the damping plate 64 may be integral with the first plate 60. In the latter case, the lower surface of the first plate 60 made of metal such as SUS is subjected to half etching to form the headers 61, 62, 63. The upper portion of the metal plate remaining on each upper end of each header serves as a damper plate 64.

The damper plate 64 is a single layer, such as a resin layer and a metal layer made of polyimide resin and SUS. Alternatively, the damping plate 64 may be in the form of a plurality of layers including a resin layer and/or a metal layer. The damping plate 64 is flat plate-shaped and elastically deformable. The damping plate 64 has a thickness that is less than the thickness of the first and second plates 60, 70. The damper plate 64 covers the upper surface of the first plate 60 and closes the upper openings of the headers 61, 62, 63 in the stacking direction.

The damper plate 64 has each end portion in its longitudinal direction (arrangement direction) formed with a plurality of (twelve) hole portions 65. The hole portion 65 is a through hole extending through the thickness of the damper plate 64. The three hole portions of each group communicate with each group of the headers 61, 62, 63 at the end portions of the damper plate 64 in the arrangement direction (fig. 4).

The second plate 70 is a flat plate whose lower surface faces the damper plate 64. The damping groove 66 is formed at the lower surface. The damping groove 66 is formed by, for example, half-etching the second plate 70 such that the damping groove 66 is recessed upward from the lower surface. Therefore, the damping groove 66 is open downward. The damper groove 66 is located between the pair of hole portions 65 of the damper plate 64 in the arrangement direction. That is, the damping grooves 66 do not extend to the distal end of the second plate 70 in the arrangement direction. The lower opening of the damper groove 66 is covered with the damper plate 64. Thus, the damper groove 66 is blocked from the headers 61, 62, 63.

The damper groove 66 extends in the array direction, and is positioned to overlap the return header in the stacking direction through the damper plate 64. For example, in the case where the first header 61 and the second header 62 are return headers, the damper grooves 66 are positioned to be aligned with the first header 61 and the second header 62 in the stacking direction. The dampening grooves 66 themselves are shown in fig. 6B.

Because the damping plate 64 is located between the damping grooves 66 and the first and second headers 61 and 62, the damping plate 64 can be deformed due to pressure fluctuations of the fluid flowing through the first and second headers 61 and 62. Therefore, the pressure fluctuation of the liquid can be attenuated. The hole portions 65 connected to the first and second headers 61 and 62 and the common header 63 are directly or indirectly connected to the tank 16.

[ third embodiment ]

Next, a head 211 according to a third embodiment will be described with reference to fig. 6A to 7. The third embodiment is the same as the second embodiment except for the second plate 170 corresponding to the second plate 70 of the second embodiment. According to the third embodiment, the flow path 33 further includes a junction passage 71, the junction passage 71 being fluidly connected to the first header 61 and the second header 62.

Specifically, the second plate 170 is formed with a plurality of engaging passages 71, each engaging passage 71 connecting each first header 61 and each second header 62 together. Each of the engagement passages 71 is positioned to overlap each of the first headers 61 and each of the second headers 62 in the stacking direction, and extends through the thickness of the second plate 170 in the stacking direction. Therefore, each of the lower opening ends of each of the joint passages 71 is connected to each of the first headers 61 and each of the second headers 62, thereby connecting each of the first headers 61 to each of the second headers 62.

The engaging passage 71 is positioned opposite to the second communication passage 52 with respect to the first header 61. The joint passage 71 is located above the first header 61. Further, the engagement passage 71 is positioned opposite to the fourth communication passage 54 with respect to the second header 62. The joint passage 71 is located above the second header 62.

As described above, since the joint passage 71 overlaps with the first header 61 and the second header 62 in the stacking direction, the flow path 33 extends from the first header 61 and the second header 62 to the joint passage 71 in the stacking direction. Therefore, the bonding path 71 can be provided without increasing the size of the head 211 in the direction perpendicular to the stacking direction.

Further, the joining passage 71 is a slit-like configuration having a rectangular sectional shape taken along a plane perpendicular to the stacking direction. That is, the engagement passage 71 is elongated to straddle between the first header 61 and the second header 62. The engagement passage 71 has one end 71x and the other end 71y in its longitudinal direction. As shown in fig. 7, the one end 71x is not positioned farther from the fourth communication passage 54 than the second communication passage 52 is from the fourth communication passage 54 in the width direction, and the other end 71y is not positioned farther from the second communication passage 52 than the fourth communication passage 54 is from the second communication passage 52 in the width direction. In other words, one end 71x is positioned to be aligned with the open end of the second communication passage 52, and the other end 71y is positioned to be aligned with the open end of the fourth communication passage 54.

With this structure, in the longitudinal direction of the engaging passage 71, the engaging passage 71 does not extend beyond the first header 61 in the direction away from the second header 62 and does not extend beyond the second header 62 in the direction away from the first header 61. In other words, the joint passage 71 is located on the first header 61 and on the second header 62 at a position between the first header 61 and the second header 62. Therefore, the liquid can flow through the first header 61, the second header 62, and the junction passage 71 without any liquid congestion.

More specifically, the engagement passage 71 includes a first engagement passage 71a and a second engagement passage 71 b. One end of the first header 61 in the longitudinal direction (array direction) and one end of the second header 62 in the longitudinal direction (array direction) are connected to each other through a first engaging passage 71 a. The other end of the first header 61 in the longitudinal direction (the arrangement direction) and the other end of the second header 62 in the longitudinal direction (the arrangement direction) are connected to each other through a second engagement passage 71 b. Therefore, the first joining passage 71a and the second joining passage 71b are distant from each other in the arrangement direction.

The liquid flows through the first header 61 and the second header 62 in the arrangement direction. Therefore, each end of the first header 61 and the second header 62 in the arrangement direction serves as a downstream end. Since the first joining passage 71a and the second joining passage 71b are connected to each downstream end, the liquid that has flowed through the first header 61 and the second header 62 can smoothly flow through the joining passage 71.

Further, each of the first engaging passage 71a and the second engaging passage 71b is connected to the first header 61 and the second header 62 through the hole portion 65 of the damper plate 64 at each end portion of the damper plate 64 in the arrangement direction. The damper groove 66 is formed in the second plate 170 at a position between the first engagement passage 71a and the second engagement passage 71b in the arrangement direction. As described above, the damper groove 66 suppresses pressure fluctuation of the liquid flowing through the first header 61 and the second header 62.

Here, the positions of the first header 61 and the second header 62 are different from each other in the arrangement direction, and the length of the first header 61 is equal to the length of the second header 62. Specifically, one end of the second header 62 in the arrangement direction is positioned farther from one end of the first header 61 in the arrangement direction than one end of the first header 170 in the arrangement direction. Therefore, one end of the first header 61 is not aligned with one end of the second header 62 in the arrangement direction. Further, the other end of the second header 62 in the arrangement direction is positioned closer to the other end of the 170 in the arrangement direction than the other end of the first header 61 in the arrangement direction. Therefore, the other end of the first header 61 is not aligned with the other end of the second header 62 in the arrangement direction.

With this arrangement, the first engagement passage 71a and the second engagement passage 71b extend obliquely at an angle θ 1 with respect to the arrangement direction. Further, the adjacent first joining passages 71a extend parallel to each other with a space therebetween in the width direction, and the adjacent second joining passages 71b extend parallel to each other with a space therebetween in the width direction. Due to the oblique orientation of the engagement passages 71, it is possible to provide a larger space between the adjacent first engagement passages 71a and a larger space between the adjacent second engagement passages 71b than in the case where the first engagement passages 71a and the second engagement passages 71b extend perpendicularly to the arrangement direction.

The angle θ 1 is greater than zero and less than 90 degrees. Preferably, the angle θ 1 is equal to or greater than 45 degrees and less than 90 degrees, for example, 70 degrees. The first engaging passage 71a and the second engaging passage 71b can connect the first header 61 to the second header 62 by setting the angle θ 1 to be larger than zero.

Further, if the interval in the width direction between the adjacent first and second headers 61 and 62 is small, the interval between the end of each of the first and second engagement passages 71a and 71b connected to the first header 61 and the end of each of the first and second engagement passages 71a and 71b connected to the second header 62 is narrow. Therefore, the liquid flowing through the first joining passage 71a and the second joining passage 71b may leak.

On the other hand, if the interval in the width direction between the adjacent first header 61 and second header 62 is large, the head becomes bulky. Further, if the angle θ 1 is set to 90 degrees, the plurality of first engagement passages 71a and second engagement passages 71b extend in the width direction, resulting in an increase in the size of the head. In contrast, by setting the angle θ 1 to be smaller than 90 degrees, each adjacent end of each of the first engagement passage 71a and the second engagement passage 71b can be displaced from each other in the arrangement direction. Therefore, a larger interval between the adjacent first and second joining passages 71a, 71b can be obtained without increasing the interval between the adjacent first and second headers 61, 62.

Further, the common header 63 has a length in the array direction smaller than the lengths of the first header 61 and the second header 62 in the array direction. One end of the common header 63 in the arrangement direction is positioned farther from one end of the second plate 170 in the arrangement direction than each of the one ends of the first header 61 and the second header 62 in the arrangement direction, and the other end of the common header 63 in the arrangement direction is positioned farther from the other end of the second plate 170 in the arrangement direction than each of the other ends of the first header 61 and the second header 62 in the arrangement direction.

With this arrangement, the common header 63 does not overlap with the first joining passage 71a and the second joining passage 71b in the stacking direction. Therefore, the common header 63 can be arranged between the first header 61 and the second header 62 without interfering with the first engagement passage 71a and the second engagement passage 71 b. The first and second joint passages 71a, 71b and the hole portions 65 (the hole portions 65 are connected to the first and second headers 61, 62 and the common header 63) are directly or indirectly connected to the tank 16.

[ fourth embodiment ]

Next, a head 311 according to a fourth embodiment will be described with reference to fig. 8 to 10, in which like parts and components are denoted by like reference numerals as shown in the foregoing embodiments. The fourth embodiment is the same as the third embodiment except that the flow path 33 of the fourth embodiment further includes a first connecting passage 81, a second connecting passage 82, a first reservoir passage 91, and a second reservoir passage 92.

The fourth embodiment further comprises reservoir plates comprising a first reservoir plate 90a and a second reservoir plate 90b, connecting plates comprising a first connecting plate 80a, a second connecting plate 80b and a third connecting plate 80c, and a filter plate 93 for providing the flow path 33. First and second reservoir passages 91 and 92 are formed in the first and second reservoir plates 90a and 90 b. The first connection path 81 is formed in the first connection plate 80a, the second connection plate 80b, and the third connection plate 80 c. The second connection path 82 is formed in the second plate 170, the first connection plate 80a, the second connection plate 80b, and the third connection plate 80 c. The filter plate 93 is located between the first reservoir plate 90a and the second reservoir plate 90b in the stacking direction.

The plates are in the shape of flat plates, and a first connecting plate 80a, a second connecting plate 80b, a third connecting plate 80c, a second reservoir plate 90b, a filter plate 93, and a first reservoir plate 90a are laminated on the second plate 170 in this order, and bonded together by an adhesive.

The first reservoir passage 91 and the second reservoir passage 92 extend in the arrangement direction and are spaced apart from each other in the width direction. The first reservoir passage 91 communicates with the first header 61 and the second header 62 through the first connecting passage 81 and the joining passage 71. The second reservoir passage 92 communicates with the common header 63 through the second connecting passage 82. Since the first header 61 and the second header 62 are connected together by the joint passages 71, four first reservoir channels 91 are formed for the eight first headers 61 and the second header 62 and four second reservoir channels 92 are formed for the four third headers 63 in the first reservoir plate 90 a.

Each of the first reservoir passage 91 and the second reservoir passage 92 penetrates the first reservoir plate 90a and the second reservoir plate 90b in the stacking direction. The lower opening ends of the first reservoir passage 91 and the second reservoir passage 92 are covered by the third connecting plate 80 c. The first reservoir passage 91 includes a first reservoir passage 91a formed in the first reservoir plate 90a and a first reservoir passage 91b formed in the second reservoir plate 90b, and the second reservoir passage 92 includes a second reservoir passage 92a formed in the first reservoir plate 90a and a second reservoir passage 92b formed in the second reservoir plate 90 b. Further, a filter 93a is formed on the filter plate 93.

The first reservoir passage 91a, the filter 93a, and the first reservoir passage 91b overlap each other in the stacking direction. The first reservoir passage 91a and the first reservoir passage 91b form a first reservoir passage 91 communicating with the tank 16.

The second reservoir passage 92a, the filter 93a provided in the filter plate 93, and the second reservoir passage 92b overlap each other in the stacking direction. The second reservoir passage 92a and the second reservoir passage 92b form a second reservoir passage 92 that communicates with the tank 16.

The filter 93a covers the lower open end of the first reservoir passage 91a and covers the upper open end of the first reservoir passage 91 b. The filter 93a also covers the lower open end of the second reservoir passage 92a and covers the upper open end of the second reservoir passage 92 b. Therefore, when the liquid flowing through the first and second reservoir passages 91 and 92 passes through the filter 93a, impurities contained in the liquid can be captured by the filter 93 a.

The first connecting passage 81 is connected to the junction passage 71 and the first reservoir passage 91. The first connection path 81 includes a pair of first portions 83, and the pair of first portions 83 are positioned away from each other in the arrangement direction. Each of the first portions 83 includes four first holes 83a, four second holes 83b, and four third holes 83 c.

Each first hole 83a extends through the thickness of the first connecting plate 80a in the stacking direction at a position overlapping each first joining passage 71a (or second joining passage 71 b). The first hole 83a has a circular cross section taken along a plane perpendicular to the stacking direction. The four first holes 83a are arrayed in the width direction with a space between the adjacent first holes 83 a.

Each of the first holes 83a is connected to an intermediate position of each of the first engaging passages 71a (or the second engaging passage 71 b). Specifically, the intermediate position is the center of each of the first engaging passages 71a (or the second engaging passages 71b) in the length direction, and the length direction is defined between one end of the first engaging passage 71a (or the second engaging passage 71b) connected to the first header 61 and the other end connected to the second header 62. Therefore, the amount of liquid flowing from the first header 61 into the first hole 83a through the first engaging passage 71a (or the second engaging passage 71b) can be equal to or close to the amount of liquid flowing from the second header 62 into the first hole 83a through the first engaging passage 71a (or the second engaging passage 71 b).

Each of the second holes 83b extends through the thickness of the second connecting plate 80b in the stacking direction at a position overlapping each of the first holes 83 a. The second hole 83b has an elliptical sectional shape taken along a plane perpendicular to the stacking direction. Thus, the second hole 83b has a lower open end connected to the upper open end of the first hole 83 a.

Each third hole 83c extends through the thickness of the third connecting plate 80c in the stacking direction at a position overlapping each second hole 83 b. The third hole 83c has a circular cross section taken along a plane perpendicular to the stacking direction. The third hole 83c has a lower open end connected to the upper open end of the second hole 83 b. Further, in the stacking direction, each third hole 83c overlaps with one end portion of each first reservoir passage 91 in the arrangement direction. Therefore, the upper open end of each third hole 83c is connected to the lower open end of the first reservoir passage 91. The four third holes 83c are arrayed in the width direction with a space between the adjacent third holes 83 c.

Thus, each of the first and second engagement passages 71a and 71b is connected to each of the first reservoir passages 91 through each of the first connection passages 81 including the first hole 83a, the second hole 83b, and the third hole 83 c. The second hole 83b has one end in its longitudinal direction connected to the first hole 83a and the other end in its longitudinal direction connected to the third hole 83 c. The longitudinal direction is deviated in a direction from the first hole 83a toward the third hole 83c with respect to the width direction and the arrangement direction.

In fig. 9, an imaginary line AL is shown. The line AL extends in the width direction at the center of the twelve headers 61, 62, 63 in the arrangement direction. Each of the second holes 83b extends obliquely with respect to the line AL such that the other end (connected to the third hole 83 c) is positioned farther from the line AL than the one end (connected to the first hole 83 a) from the line AL. Further, the four second holes 83b arrayed in the width direction have lengths in the arrayed direction equal to each other.

Therefore, the length of the first reservoir passage 91 connected to the other end portion of the second hole 83b through the third hole 83c is larger than the length of the first header 61 and the second header 62 connected to the one end portion of the second hole 83b through the first engaging passage 71a (second engaging passage 71b) and the first hole 83 a.

In fig. 9, another imaginary line WL is shown. The line WL extends in the arrangement direction at the center in the width direction of the twelve headers 61, 62, 63. Each of the second holes 83b extends obliquely with respect to the line WL. The inclination of the two second holes 83b located on one side of the line WL in the width direction is opposite to the inclination of the remaining two second holes 83b located on the other side of the line WL in the width direction, so that the other end portions (connected to the third holes 83 c) of the second holes 83b are positioned farther from the line WL than the one end portions (connected to the third holes 83 a) of the second holes 83 b.

Further, the second hole 83b positioned farther from the line WL in the width direction than the other second hole 83b has a length in the width direction larger than that of the other third hole 83 c. Thus, the second hole 83b positioned farther from the line WL than the other second hole 83b from the line WL in the width direction defines an angle θ 2 with respect to the line AL, the angle θ 2 being smaller than an angle defined between the other second hole 83b and the line AL. For example, another second hole 83b located beside the line WL defines an angle θ 2 with respect to the line AL of 70 degrees, while the second hole 83b furthest from the line WL defines an angle θ 2 with respect to the line AL of 45 degrees. Therefore, by setting the angle θ 2 to not less than 45 degrees, interference between the adjacent second holes 83b can be avoided without increasing the size of the head 311 in the width direction.

With this arrangement, the interval between the adjacent third holes 83c is larger than the interval between the adjacent first holes 83a in the width direction. Thus, by forming the third hole 83c, as the first connection passage 81 travels from the first engagement passage 71a (the second engagement passage 71b) connected to the first portion 83a toward the first reservoir passage 91 connected to the second hole 83b, the first connection passage 81 extends in a direction away from the line WL.

In this way, the position of the first reservoir passage 91 in the width direction with respect to the first header 61 and the second header 62 can be adjusted by providing the first connection passage 81. Therefore, the dimensions of the first reservoir passage 91 in the width direction and the arrangement direction can be larger than those of the first header 61 and the second header 62. As a result, the sectional area of the first reservoir passage 91 can be larger than the sectional areas of the first header 61 and the second header 62, so that shortage of the liquid supplied to the pressure chamber 31 can be eliminated.

The second connection passage 82 is connected to the second reservoir passage 92 and the common header 63. The second connecting passage 82 includes a pair of end connecting passages 84, and the pair of end connecting passages 84 are positioned away from each other in the arrangement direction. Each end connection passage 84 includes four first hole portions 84a, four second hole portions 84b, four third hole portions 84c, and four fourth hole portions 84 d.

Each of the first hole portions 84a extends through the thickness of the second plate 170 in the stacking direction at a position overlapping each of the common headers 63 to communicate with the common headers 63. The first hole portion 84a has a circular cross section taken along a plane perpendicular to the stacking direction. The first hole portion 84a is positioned closer to the line AL than the first joining passage 71a (second joining passage 71b) in the arrangement direction. Further, the first hole portion 84a is located at the center of the first joining passage 71a (the second joining passage 71b) in the width direction. The four first hole portions 84a are arranged in the width direction with a space between adjacent first hole portions 84 a.

Each of the second hole portions 84b extends through the thickness of the first connecting plate 80a in the stacking direction at a position overlapping each of the first hole portions 84 a. The second hole portion 84b has a circular cross section taken along a plane perpendicular to the stacking direction. The second hole portion 84b is aligned with the first hole 83a in the arrangement direction, and the second hole portion 84b is positioned closer to the line AL than the first hole 83 a.

Each third hole portion 84c extends through the thickness of the second connecting plate 80b in the stacking direction at a position overlapping each second hole portion 84b to communicate with the second hole portion 84 b. The third hole portion 84c has an elliptical sectional shape taken along a plane perpendicular to the stacking direction.

Each fourth aperture portion 84d extends through the thickness of the third web 80c at a location that overlaps each third aperture portion 84 c. The third hole portion 84c has a circular cross section taken along a plane perpendicular to the stacking direction. The fourth bore portion 84d has a lower open end connected to the upper open end of the third bore portion 84 c. Further, the fourth hole portion 84d is positioned to overlap with the end portion of the second reservoir passage 92 in the arrangement direction in the stacking direction, and the fourth hole portion 84d has an upper opening end connected to the lower opening end of the second reservoir passage 92.

The third hole portion 84c extends in the width direction, and the third hole portion 84c has one end connected to the second hole portion 84b and the other end connected to the fourth hole portion 84d in the width direction. In other words, the third hole portion 84c extends in a direction away from the line WL in a direction from the second hole portion 84b toward the fourth hole portion 84 d.

Specifically, two third hole portions 84c located on one side of the line WL in the width direction extend in one width direction, and the remaining two third hole portions 84c located on the other side of the line WL in the width direction extend in the opposite width direction. Further, the third hole portion 84c positioned farther from the line WL than the other third hole portion 84c has a length greater than that of the other third hole portion 84 c. Therefore, in the width direction, the interval between the adjacent fourth hole portions 84d is larger than the interval between the adjacent second hole portions 84 b. Thus, by forming the third hole portion 84c, the second connection passage 82 extends in a direction away from the line WL as the second connection passage 82 travels from the common header 63 connected to the first and second hole portions 84a, 84b toward the second reservoir passage 92 connected to the fourth hole portion 84 d.

In this way, the position of the second reservoir passage 92 relative to the common header 63 can be adjusted by providing the second connection passage 82. Therefore, the dimension of the second reservoir passage 92 in the width direction can be larger than the dimension of the common header 63. As a result, the sectional area of the second reservoir passage 92 can be larger than the sectional area of the common header 63, so that shortage of the liquid supplied to the pressure chamber 31 can be eliminated.

[ fifth embodiment ]

A head 411 according to a fifth embodiment will be described with reference to fig. 11, in which like parts and components are denoted by like reference numerals as shown in the preceding embodiments. The fifth embodiment is the same as the fourth embodiment except for the following: in the fifth embodiment, the joint passage 71c further includes an intermediate joint passage 71c in addition to the first joint passage 71a and the second joint passage 71b, the first connection passage 81 further includes a first intermediate connection passage 85 in addition to the first portion 83, and the second connection passage 82 further includes a second intermediate connection passage 86 in addition to the end connection passage 84.

The first engaging passage 71a connects one end portion in the arrangement direction of the first header 61 and one end portion in the arrangement direction of the second header 62 together. The second joining passage 71b connects the other end portion in the array direction of the first header 61 and the other end portion in the array direction of the second header 62 together. The intermediate joining passage 71 extends in the width direction at a position between the first joining passage 71a and the second joining passage 71b in the arrangement direction. The intermediate joint passage 71 connects together the intermediate portion in the array direction of the first header 61 and the intermediate portion in the array direction of the second header 62.

Therefore, the liquid flows from the first header 61 and the second header 62 into the first joining passage 71a, the second joining passage 71b, and the intermediate joining passage 71 c. Therefore, the liquid flowing out from the first header 61 and the second header 62 can be smoothly joined at the first joining passage 71a, the second joining passage 71b, and the intermediate joining passage 71 c.

Further, a plurality of intermediate joint passages 71c including the first path 71c1, the second path 71c2, the third path 71c3, and the fourth path 71c4 are formed in the head 411. The first path 71c1 and the third path 71c3 are aligned in a straight line in the width direction, and the second path 71c2 and the fourth path 71c4 are aligned in a straight line in the width direction. Further, the arrangement of the first path 71c1 and the third path 71c3 and the arrangement of the second path 71c2 and the fourth path 71c4 are distant from each other in the arrangement direction. Since the adjacent intermediate joint passages 71c (e.g., the first path 71c1 and the second path 71c2) are not aligned in the width direction, it is possible to provide a large interval between the adjacent intermediate joint passages 71c in the width direction, thereby avoiding leakage of liquid.

As described above, the first portion 83 is connected to the first engagement passage 71a, the second engagement passage 71b, and the end of the first reservoir passage 91. The first portion 83 connected to the first joining passage 71a is connected to one end portion of the first reservoir passage 91 in the arrangement direction, and the first portion 83 connected to the second joining passage 71b is connected to the other end portion of the first reservoir passage 91 in the arrangement direction. As described above, the first portion 83 includes the first hole 83a, the second hole 83b, and the third hole 83 c.

The first intermediate connection passage 85 is located between the pair of first portions 83 in the arrangement direction, and the first intermediate connection passage 85 is connected to the intermediate joint passage 71c and an intermediate position of the first reservoir passage 91. The first intermediate connection path 85 includes a first connection portion 85a, a second connection portion 85b, and a third connection portion 85 c.

The first connection portion 85a extends through the thickness of 280a at a position overlapping with the first connection portion 85a in the stacking direction. The first connecting portion 85a is connected to the central portions of the intermediate joint passage 71c in the longitudinal direction, which are connected to the first header 61 and the second header 62.

The second connecting portion 85b extends through the thickness of 280b at a position overlapping with the first connecting portion 85a in the stacking direction. The third connecting portion 85c extends through the thickness of the third connecting plate 280c at a position overlapping with the second connecting portion 85b in the stacking direction.

The second connecting portion 85b extends in the width direction, and the second connecting portion 85b has one end connected to the first connecting portion 85a and the other end connected to the third connecting portion 85c in the width direction. Two second connecting portions 85b are located on one side of the center line WL in the width direction, and the remaining two second connecting portions 85b are located on the other side of the center line WL in the width direction. Of each set of two second connection portions 85b located on both sides of the center line WL, the second connection portion 85b located farther from the center line WL than the other second connection portion 85b has a length greater than that of the other second connection portion 85 b. The interval in the width direction between the adjacent third connecting portions 85c is larger than the interval in the width direction between the adjacent first connecting portions 85 a.

Thus, by the second connection portion 85b, the first intermediate connection passage 85 extends from the intermediate joint passage 71c connected to the first connection portion 85a toward the first reservoir passage 91 connected to the third connection portion 85c in a direction away from the center line WL. Therefore, the first reservoir passage 91 can have a width larger than the widths of the first header 61 and the second header 62, thereby avoiding a shortage of the liquid supplied to the pressure chamber 31.

The third connecting portion 85c of the first intermediate connecting passage 85 and the pair of third holes 83c aligned with each other in the alignment direction are aligned in a straight line in the alignment direction. The third connecting portion 85c is an end of the first intermediate connecting passage 85 connected to the first reservoir passage 91, and the pair of third holes 83c are ends of the first portion 83 connected to the first reservoir passage 91. In other words, the pair of first portions 83 and the first intermediate connecting passage 85 are connected to one first reservoir passage 91.

The end connection passage 84 is connected to an end portion of the common header 63 in the arrangement direction and to the second reservoir passage 92. Specifically, a pair of end connection passages 84 are provided, and one end connection passage 84 of the pair of end connection passages 84 is connected to one end of the common header 63 in the arrangement direction and to one end of the second reservoir passage 92 in the arrangement direction. The remaining one of the pair of end connection passages 84 is connected to the other end of the common header 63 in the arrangement direction and to the other end of the second reservoir passage 92 in the arrangement direction. As described above, the end connection passage 84 includes the first hole portion 84a, the second hole portion 84b, the third hole portion 84c, and the fourth hole portion 84 d.

The second intermediate connection passage 86 is connected to an intermediate position of the common header 63 and to an intermediate position of the second reservoir passage 92 at a position between the pair of end connection passages 84 in the arrangement direction. The second intermediate connecting passage 86 includes a first passage 86a, a second passage 86b, a third passage 86c, and a fourth passage 86 d.

The first passage 86a extends through the thickness of the second plate 270 in the stacking direction at a position overlapping the common header 63 in the stacking direction. The first passage 86a communicates with the common header 63. The plurality of (four) first passages 86a are aligned in the width direction at positions between the first path 71c1 and the second path 71c2 and between the third path 71c3 and the fourth path 71c 4.

The second passage 86b extends through the thickness of the first connecting plate 280a in the stacking direction at a position overlapping the first passage 86a in the stacking direction. The second passage 86b communicates with the first passage 86 a. The third channel 86c extends through the thickness of the second connecting plate 280b in the stacking direction at a position overlapping the second channel 86b in the stacking direction. The fourth passage 86d extends through the thickness of the third connecting plate 280c in the stacking direction at a position overlapping with the third passage 86c in the stacking direction.

The third passage 86c includes a first section 86c1, a second section 86c2, a third section 86c3, and a fourth section 86c4 arranged in the width direction in this order. The second and third sections 86c2 and 86c3, which are positioned closer to the center line WL in the width direction than the first and fourth sections 86c1 and 86c4, have circular cross sections taken along a plane perpendicular to the stacking direction. The first and fourth segments 86c1 and 86c4, which are positioned farther from the center line WL in the width direction than the second and third segments 86c2 and 86c3, have elliptical cross-sectional shapes extending in the width direction, taken along a plane perpendicular to the stacking direction.

Each of the first section 86c1 and the fourth section 86c4 has one end in its lengthwise direction connected to the second channel 86b and has the other end in its lengthwise direction connected to the fourth channel 86 d. Therefore, the interval in the width direction between the adjacent fourth passages 86d is larger than the interval in the width direction between the adjacent second passages 86 b.

Thus, through the third passage 86c, the second intermediate connection passage 86 extends in the width direction in a direction away from the center line WL from the common header 63 connected to the first passage 86a and the second passage 86b toward the second reservoir passage 92 connected to the fourth passage 86 d. Therefore, the second reservoir passage 92 can have a width larger than that of the common header 63, thereby avoiding a shortage of the liquid supplied to the pressure chamber 31.

The fourth passage 86d of the second intermediate connecting passage 86 and the pair of fourth hole portions 84d aligned with each other in the alignment direction are aligned in a straight line in the alignment direction. The fourth channel 86d is an end portion of the second intermediate connection passage 86 connected to the second reservoir passage 92, and the pair of fourth hole portions 84d are end portions of the end connection passage 84 connected to the second reservoir passage 92. In other words, the pair of end connection passages 84 and the second intermediate connection passage 86 are connected to one second reservoir passage 92.

Incidentally, in the fifth embodiment described above, the intermediate joining passage 71c extends in the width direction. However, the intermediate joint passage 71c may extend obliquely with respect to the arrangement direction and the width direction.

The above-described embodiments may be combined as long as the combination does not cause a collision problem. The above-described techniques described herein may be embodied in various forms without departing from the spirit of the essential characteristics thereof. Accordingly, the described embodiments are intended to be illustrative only and not limiting, since the scope of the disclosure is defined by the appended claims rather than by the foregoing description. Accordingly, all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.