Liquid ejecting head unit and liquid ejecting apparatus

文档序号：693760 发布日期：2021-05-04 浏览：28次中文

阅读说明：本技术 液体喷头单元及液体喷出装置 (Liquid ejecting head unit and liquid ejecting apparatus ) 是由佐藤达也中野修一于 2020-10-27 设计创作，主要内容包括：提供一种液体喷头单元及液体喷出装置。在检测配线损伤的结构中减少误测,该配线供给用于驱动液体喷头单元中的喷出部的固定电位。液体喷头单元,具备：喷出部,喷出液体；第一配线,用于供给用以驱动喷出部的固定电位；第二配线,传输规定喷出部中的液体的喷出定时的脉冲信号；第一计数器,其计数值基于第一配线中的电位变化而变化；第二计数器,其计数值基于第二配线中的电位变化而变化；以及喷出限制部,根据第一计数器的计数值和第二计数器的计数值来限制喷出部中的液体的喷出动作。(A liquid ejecting head unit and a liquid ejecting apparatus are provided. In a structure for detecting damage to wiring which supplies a fixed potential for driving a discharge portion in a liquid discharge head unit, erroneous detection is reduced. A liquid ejecting head unit includes: a discharge section for discharging a liquid; a first wiring for supplying a fixed potential for driving the ejection section; a second wiring for transmitting a pulse signal for specifying a discharge timing of the liquid in the discharge section; a first counter whose count value changes based on a potential change in the first wiring; a second counter whose count value changes based on a potential change in the second wiring; and a discharge limiting section that limits a discharge operation of the liquid in the discharge section based on the count value of the first counter and the count value of the second counter.)

1. A liquid ejecting head unit is provided with:

a discharge section for discharging a liquid;

a first wiring for supplying a fixed potential for driving the ejection section;

a second wiring line that transmits a pulse signal that specifies a discharge timing of the liquid in the discharge portion;

a first counter whose count value changes based on a potential change in the first wiring;

a second counter whose count value changes based on a potential change in the second wiring; and

and an ejection regulating section for regulating the ejection operation of the liquid in the ejection section based on the count value of the first counter and the count value of the second counter.

2. The liquid ejection head unit according to claim 1,

the pulse signal is a latch signal.

3. The liquid ejection head unit according to claim 1 or 2,

the ejection limiting section limits the ejection operation of the liquid in the ejection section based on a ratio between a change amount of the count value of the first counter and a change amount of the count value of the second counter in a predetermined period.

4. The liquid ejection head unit according to claim 3,

the predetermined period is a period in which the amount of change in the count value of the first counter becomes a predetermined amount,

the ejection limiting portion limits the ejection operation of the liquid in the ejection portion when a variation amount of the count value of the second counter is smaller than a threshold value within the predetermined period.

5. The liquid ejection head unit according to claim 4,

the ejection limiting section determines whether or not an amount of change in the count value of the second counter within the predetermined period is smaller than a threshold value when the count value of the first counter reaches a predetermined value.

6. The liquid ejection head unit according to claim 3,

the predetermined period is a period in which the amount of change in the count value of the second counter becomes a predetermined amount,

the ejection limiting portion limits the ejection operation of the liquid in the ejection portion when a change amount of the count value of the first counter exceeds a threshold value within the predetermined period.

7. The liquid ejection head unit according to claim 6,

the ejection limiting section determines whether or not an amount of change in the count value of the first counter exceeds a threshold value within the predetermined period when the count value of the second counter reaches a predetermined value.

8. The liquid ejection head unit according to any one of claims 1 to 2 and 4 to 7,

the liquid ejecting head unit is used by being mounted on a serial printer.

9. A liquid ejecting apparatus includes:

a discharge section for discharging a liquid;

a first wiring for supplying a fixed potential for driving the ejection section;

a power supply circuit configured to supply the fixed potential to the first wiring using power supplied from a commercial power supply;

a second wiring line that transmits a pulse signal that specifies a discharge timing of the liquid in the discharge portion;

a first counter whose count value changes in accordance with a potential change in the first wiring;

a second counter whose count value changes in accordance with a potential change in the second wiring; and

and an ejection regulating section for regulating the ejection operation of the liquid in the ejection section based on the count value of the first counter and the count value of the second counter.

10. The liquid ejection device according to claim 9,

the pulse signal is a latch signal.

11. The liquid ejection device according to claim 9 or 10,

12. The liquid ejection device according to claim 11,

the predetermined period is a period in which the amount of change in the count value of the first counter becomes a predetermined amount,

13. The liquid ejection device according to claim 12,

14. The liquid ejection device according to claim 11,

the predetermined period is a period in which the amount of change in the count value of the second counter becomes a predetermined amount,

15. The liquid ejection device according to claim 14,

16. The liquid ejection device according to any one of claims 9 to 10 and 12 to 15,

the liquid ejecting apparatus includes:

a housing to which the power supply circuit is fixed;

a carriage on which the ejection unit is mounted and which reciprocates in a predetermined direction with respect to the housing; and

a flexible flat cable including the first wiring and the second wiring, and connecting the power supply circuit and the carriage.

Technical Field

The present invention relates to a liquid ejecting head unit and a liquid ejecting apparatus.

Background

Conventionally, a liquid ejecting apparatus which ejects a liquid such as ink, as typified by an ink jet printer, is known. For example, as disclosed in patent document 1, such an apparatus has a liquid ejection head unit including a liquid ejection head for ejecting liquid. The liquid ejecting head unit is electrically connected to a substrate mounted on the apparatus main body via a cable such as a flexible flat cable.

Such a cable may be damaged by aging, such as breakage of the wiring. In particular, as shown in patent document 1, when the carriage reciprocates relative to the apparatus main body, the cable is repeatedly deformed in accordance with the reciprocation, and thus there is a risk of damage to the wiring. Thus, the device described in patent document 1 detects damage to the wiring based on the voltage value of the wiring provided on the cable.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 2010-52166

Disclosure of Invention

Technical problem to be solved by the invention

However, in the device described in patent document 1, since whether or not the wiring is damaged is determined only from the voltage value of the wiring, when used in an environment where the voltage value of a commercial power supply fluctuates such as an emerging country, the wiring damage may be erroneously detected due to the influence of the voltage value fluctuation. Therefore, in the device described in patent document 1, there is a problem that the operation of the device is unnecessarily restricted due to the erroneous detection, resulting in a lack of usability.

Means for solving the problems

In order to solve the above problem, a liquid ejecting head unit according to a preferred embodiment of the present invention includes: a discharge section for discharging a liquid; a first wiring for supplying a fixed potential for driving the ejection section; a second wiring line that transmits a pulse signal that specifies a discharge timing of the liquid in the discharge portion; a first counter whose count value changes based on a potential change in the first wiring; a second counter whose count value changes based on a potential change in the second wiring; and a discharge limiting unit that limits a discharge operation of the liquid in the discharge unit based on the count value of the first counter and the count value of the second counter.

Further, a liquid discharge apparatus according to a preferred embodiment of the present invention includes: a discharge section for discharging a liquid; a first wiring for supplying a fixed potential for driving the ejection section; a power supply circuit configured to supply the fixed potential to the first wiring using power supplied from a commercial power supply; a second wiring line that transmits a pulse signal that specifies a discharge timing of the liquid in the discharge portion; a first counter whose count value changes in accordance with a potential change in the first wiring; a second counter whose count value changes in accordance with a potential change in the second wiring; and a discharge limiting section that limits a discharge operation of the liquid in the discharge section based on the count value of the first counter and the count value of the second counter.

Drawings

Fig. 1 is a perspective view showing a schematic configuration of a liquid ejecting apparatus according to a first embodiment.

Fig. 2 is a block diagram showing an electrical configuration of the liquid ejecting apparatus according to the first embodiment.

Fig. 3 is a cross-sectional view showing a schematic configuration of a recording head including a discharge portion.

Fig. 4 is a diagram showing an electrical structure of the liquid ejection head unit.

Fig. 5 is a timing chart for explaining an example of the operation of the liquid ejecting head unit.

Fig. 6 is a diagram for explaining a determination period of the ejection limiting portion in the first embodiment.

Fig. 7 is a flowchart for explaining the operation of the ejection regulating section in the first embodiment.

Fig. 8 is a diagram for explaining a determination period of the ejection limiting portion in the second embodiment.

Fig. 9 is a flowchart for explaining the operation of the ejection regulating section in the second embodiment.

Fig. 10 is a diagram for explaining a determination period of the ejection limiting portion in modification 1.

Fig. 11 is a timing chart for explaining the operation of the ejection regulating unit in modification 1.

Description of the symbols

1 … liquid ejection device, 20 … carriage, 53 … power supply circuit, 60 … cable, 61 … wiring, 62 … wiring, 81 … first counter, 82 … second counter, 83 … ejection limiting section, D … ejection section, HU … head unit, LAT … latch signal, Td … determination period, VHV … power supply potential.

Detailed Description

Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. However, in the drawings, the size and the proportion of each part are different from the actual ones. In addition, the embodiments described below are preferable specific examples of the present invention, and therefore various technically preferable limitations are attached, and the scope of the present invention is not limited to these forms unless otherwise specified in the following description to limit the present invention.

A1. First embodiment

A1-1 overview of the liquid ejecting apparatus 1

Fig. 1 is a perspective view showing a schematic configuration of a liquid discharge apparatus 1 according to an embodiment. The liquid discharge apparatus 1 is an ink jet printer that performs printing by discharging ink, which is an example of a liquid, as droplets onto a print medium P. A typical example of the printing medium P is a printing paper. However, the printing medium P is not limited to printing paper, and may be a printing target made of any material such as a resin film or a fabric.

In the example shown in fig. 1, the liquid ejection apparatus 1 is a serial printer. Specifically, as shown in fig. 1, the liquid ejection device 1 has a housing 10, a carriage 20, a movement mechanism 30, a conveyance mechanism 40, and a control module 50.

In the liquid ejecting apparatus 1, print data is supplied to the control module 50 from a host computer, which is an external device such as a personal computer or a digital camera, not shown. Under the control of the control module 50, the transport mechanism 40 transports the print medium P in the sub-scanning direction, and the moving mechanism 30 reciprocates the carriage 20 in the main scanning direction, and the head unit HU mounted on the carriage 20 ejects ink toward the print medium P. At this time, the control module 50 controls the operation of the head unit HU based on the print data, thereby printing an image corresponding to the print data on the print medium P.

Next, first, the structure of each part in the liquid ejection device 1 is briefly described based on fig. 1. Further, for convenience of description, the following description is made using X, Y, and Z axes orthogonal to each other as appropriate. One direction along the X axis is referred to as an X1 direction, and the direction opposite to the X1 direction is referred to as an X2 direction. Similarly, one direction along the Y axis is referred to as a Y1 direction, and the direction opposite to the Y1 direction is referred to as a Y2 direction. One direction along the Z axis is referred to as the Z1 direction, and the opposite direction to the Z1 direction is referred to as the Z2 direction. In this embodiment, one or both of the Y1 direction and the Y2 direction are the main scanning direction, and the X1 direction is the sub scanning direction. However, the X, Y, and Z axes are not limited to being orthogonal to each other, and may intersect each other within a range that does not adversely affect the operation of the liquid ejection device 1.

The housing 10 is a structure that supports the moving mechanism 30 and the conveying mechanism 40.

The moving mechanism 30 is a mechanism that reciprocates the carriage 20 in the Y1 direction and the Y2 direction with respect to the housing 10. Specifically, the moving mechanism 30 has a guide shaft 31, a pair of pulleys 32 and 33, a timing belt 34, a motor 35, and an encoder 37.

The guide shaft 31 is fixed to the housing 10, formed in a bar shape extending along the Y axis, and movably supports the carriage 20 along the Y axis. The pulley 32 is rotationally driven by a motor 35. The pulley 33 is driven to rotate by a driving force transmitted from the pulley 32 via the timing belt 34. The timing belt 34 is formed in an endless shape, and is stretched over a pair of pulleys 32 and 33 in a state of extending along the guide shaft 31. The carriage 20 is fixed to a part of the timing belt 34 in the circumferential direction.

The decoder 37 is a transmissive linear encoder that detects the position of the carriage 20 in the Y1 direction or the Y2 direction. The decoder 37 has a scale 37a and an optical sensor 37 b. The scale 37a is a band-shaped light-transmissive member fixed to the housing 10 and arranged along the Y axis. Although not shown, the scale 37a is further provided with a plurality of light-shielding patterns arranged at predetermined intervals in the longitudinal direction by printing or the like. The optical sensor 37b is fixed to the carriage 20, and outputs a signal corresponding to a change in the relative position of the scale 37 a. Although not shown, the optical sensor 37b includes a light emitting element that emits light toward the scale 37a, and a light receiving element that receives light transmitted through the scale 37a from the light emitting element. The decoder 37 is not limited to the configuration shown in fig. 1 as long as it can detect the position of the carriage 20 in the Y1 direction or the Y2 direction, and may be a reflective linear decoder, for example.

In the above-described movement mechanism 30, by alternately switching the rotation of the motor 35 between the forward direction and the reverse direction, the carriage 20 is reciprocated in the Y1 direction and the Y2 direction along the guide shaft 31 in accordance with the driving force transmitted from the motor 35 to the carriage 20 via the timing belt 34. In addition, the output of the decoder 37 is input to the control module 50, and is appropriately used to control the respective portions of the liquid ejection device 1.

The conveyance mechanism 40 is a mechanism that conveys the print medium P in the X1 direction with respect to the casing 10. Specifically, the conveyance mechanism 40 includes a platen 41, a conveyance roller 42, and a motor 43. The platen 41 is a plate-shaped base that supports the printing medium P to which ink is applied from the head unit HU. The printing medium P is fed one by one onto the platen 41 by a paper feed roller, not shown. The conveying roller 42 is rotationally driven by a motor 43, and conveys the print medium P on the platen 41 in the X1 direction.

By the above-described cooperative operation of the moving mechanism 30 and the conveying mechanism 40, the relative position of the carriage 20 with respect to the print medium P is changed in both the direction along the X axis and the direction along the Y axis. The head unit HU and the plurality of ink cartridges C are mounted on the carriage 20.

Each of the plurality of ink cartridges C contains ink supplied to the head unit HU. The ink cartridges C contain different kinds of ink. In the example shown in fig. 1, the number of the ink cartridges C is four, and the colors of the inks contained in the four ink cartridges C are different from each other. As the colors of the inks contained in the four ink cartridges C, for example, four colors of cyan, magenta, yellow, and black are cited. The plurality of ink cartridges C may be mounted on the casing 10 instead of the carriage 20. In this case, for example, ink may be supplied from the plurality of ink cartridges C to the head unit HU via the tubes. The number of ink cartridges C included in the head unit HU may be three or less, or five or more.

The head unit HU ejects ink from the plurality of ink cartridges C toward the print medium P as droplets. In the example shown in fig. 1, the head unit HU receives the four colors of ink from the four ink cartridges C described above and ejects the four colors of ink.

The carriage 20 described above is electrically connected to the control module 50 via a cable 60. In the example shown in fig. 1, the cable 60 is a flexible flat cable. Further, the cable 60 is not limited to a flexible flat cable, and may be a flexible wiring board, for example.

A1-2 electric structure of liquid ejecting apparatus 1

Fig. 2 is a block diagram showing an electrical configuration of the liquid discharge apparatus 1 according to the first embodiment. As shown in fig. 2, the moving mechanism 30 includes a motor driver 36 for driving the motor 35 in addition to the above-described components. The conveying mechanism 40 includes a motor driver 44 for driving the motor 43 in addition to the above-described components. Additionally, a portion or all of the motor drive 36 or 44 may be included in the control module 50.

The head unit HU has a recording head HD, a supply circuit 70, and a limiting circuit 80. The recording head HD has a plurality of discharge portions D that discharge ink. The supply circuit 70 supplies a supply drive signal Vin for driving the discharge section D to one or more discharge sections D selected from the plurality of discharge sections D. When a damage of the wiring in the cable 60 is detected, the limiting circuit 80 limits the ejection of the ink in the recording head HD. The above recording head HD, cable 60, supply circuit 70, and limiting circuit 80 will be described in detail later.

In the example shown in fig. 2, the number of recording heads HD included in the head unit HU is one, but the number is not limited to this, and the number of recording heads HD included in the head unit HU may be two or more. In addition, the recording head HD may have one ejection portion D. In the following description, when the number of the discharge portions D included in the recording head HD is M, the discharge portions D may be represented as discharge portions D [ M ] by using subscripts [ M ] in order to distinguish the M discharge portions D from each other. However, both M and N are natural numbers of 1 or more. Note that M other components or signals in the liquid ejecting apparatus 1 may be associated with the ejecting section D [ M ] by using the subscript [ M ].

The control module 50 is a circuit for controlling the driving of the moving mechanism 30, the conveying mechanism 40, and the head unit HU. Specifically, the control module 50 has a control circuit 51, a storage circuit 52, a power supply circuit 53, and a drive signal generation circuit 54.

The control circuit 51 has a function of controlling the operation of each part of the liquid ejection device 1 and a function of processing various data. The control circuit 51 includes a processor such as one or more CPUs (Central Processing units). The control circuit 51 may include a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to the CPU.

The storage circuit 52 stores various programs executed by the control circuit 51 and various data such as print data Img processed by the control circuit 51. The Memory circuit 52 includes, for example, one or both of a volatile Memory such as a RAM (Random Access Memory) and a nonvolatile Memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). The print data Img is supplied from a host computer as an external device such as a personal computer or a digital camera, not shown.

The power supply circuit 53 receives supply of electric power from a commercial power supply, not shown, and generates predetermined various potentials. Specifically, the power supply circuit 53 generates a high-potential-side power supply potential VHV, a low-potential-side power supply potential VDD, and an offset potential VBS. As the setting values of these potentials, for example, the power supply potential VHV is about 42V, the power supply potential VDD is about 3.3V, and the offset potential VBS is about 6V. These potentials are supplied to the head unit HU via the cable 60. Here, the power supply potential VHV is an example of a "fixed potential" supplied to the first wiring included in the cable 60. The power supply potential VHV is also supplied to the drive signal generation circuit 54. Although not shown, a reference potential of 0V, which is a reference value of the above potentials, is supplied to the head unit HU via the cable 60.

The drive signal generation circuit 54 is a circuit that generates a drive signal Com for driving the discharge unit D. Specifically, the drive signal generation circuit 54 has, for example, a DA conversion circuit and an amplification circuit. The drive signal generation circuit 54 is configured to convert the waveform designation signal dCom from the control circuit 51 from a digital signal to an analog signal, and the amplification circuit amplifies the analog signal using the power supply potential VHV from the power supply circuit 53 to generate the drive signal Com. Here, among the waveforms included in the drive signal Com, the waveform actually supplied to the ejection section D is the supply drive signal Vin. The waveform designating signal dCom is a digital signal for defining the waveform of the drive signal Com.

The control circuit 51 has the following functions: the operation of each part of the liquid ejection device 1 is controlled by executing a program stored in the storage circuit 52. Specifically, the control circuit 51 executes the program to generate the control signals CNT1 and CNT2, the print signal SI, the waveform designation signal dCom, the clock signal CLK, the latch signal LAT, and the change signal CNG as signals for controlling the operations of the respective parts of the liquid ejection device 1. Here, the latch signal LAT is an example of a "pulse signal" transmitted to the second wiring included in the cable 60.

The control signal CNT1 is a signal for controlling the driving of the moving mechanism 30. The control signal CNT1 is supplied to the motor driver 36 of the moving mechanism 30. The motor driver 36 drives the motor 35 in accordance with the control signal CNT 1.

The control signal CNT2 is a signal for controlling the driving of the conveyance mechanism 40. The control signal CNT2 is supplied to the motor driver 44 of the conveyance mechanism 40. The motor driver 44 drives the motor 43 in accordance with the control signal CNT 2.

The print signal SI is a digital signal for specifying the operation type of the ejection section D. Specifically, the print signal SI specifies the operation type of the ejection unit D by specifying whether or not the drive signal Com is supplied to the ejection unit D. Here, the designation of the operation type of the ejection portion D is, for example, a designation of whether or not to drive the ejection portion D, a designation of whether or not to eject ink from the ejection portion D when driving the ejection portion D, or a designation of an amount of ink ejected from the ejection portion D when driving the ejection portion D.

The latch signal LAT and the change signal CNG are used together with the print signal SI to define the timing of ink ejection from the ejection section D. For example, based on the output of the decoder 37 described above, the timing of the pulses included in these signals is set to a timing synchronized with the movement of the carriage 20.

A1-3, schematic structure of discharge section D

Fig. 3 is a cross-sectional view showing a schematic configuration of the recording head HD including the ejection portion D. As shown in fig. 3, the recording head HD includes a nozzle plate 91, a flow path substrate 92, a vibration plate 93, and a plurality of piezoelectric elements PZ. These are laminated in the order of the nozzle plate 91, the flow path substrate 92, the vibration plate 93, and the plurality of piezoelectric elements PZ.

The nozzle plate 91 has a plurality of nozzles N arranged in a predetermined direction. Each of the plurality of nozzles N is a through hole through which ink passes. The flow path substrate 92 has a plurality of chambers SC, a reservoir SRV, a plurality of ink supply paths SS, and an ink inlet OI formed therein. The chamber SC is a space provided separately for each nozzle N and communicating with the nozzle N. The reservoir SRV is a space provided in common for the plurality of nozzles N and extending in the arrangement direction of the plurality of nozzles N. The plurality of ink supply paths SS are spaces which are provided individually for each nozzle N and which communicate the plurality of chambers SC with the reservoir SRV. The ink inlet OI is an opening for introducing ink from the ink cartridge C into the reservoir SRV. The vibration plate 93 constitutes a part of the wall surface of each of the plurality of chambers SC, and is a plate-like member elastically deformable in a direction of changing the volume of the chamber SC per chamber SC.

In the example shown in fig. 3, each of the plurality of piezoelectric elements PZ is a unimorph (single crystal) type piezoelectric element. Specifically, each of the plurality of piezoelectric elements PZ has an upper electrode Zu, a piezoelectric body Zm, and a lower electrode Zd. They are laminated in this order. The offset potential VBS from the power supply circuit 53 is supplied to the lower electrode Zd. The supply drive signal Vin, which is composed of a part or all of the waveform included in the drive signal Com from the drive signal generation circuit 54, is supplied to the upper electrode Zu. By applying a voltage based on the potential difference between the offset potential VBS and the supply drive signal Vin between the upper electrode Zu and the lower electrode Zd, the piezoelectric element PZ vibrates the vibration plate 93 in the Z1 direction or the Z2 direction in accordance with the inverse piezoelectric effect of the piezoelectric body Zm. By this vibration, the pressure in the chamber SC changes with the change in the volume of the chamber SC, and ink is ejected from the nozzle N. The structure of the piezoelectric element PZ is not limited to the unimorph type, and may be, for example, a bimorph type, a laminated type, or the like.

Among the components of the recording head HD described above, the aggregate of the components provided for each nozzle N is the discharge portion D. Here, the ejection section D includes a chamber SC, a piezoelectric element PZ, and a nozzle N.

A1-4. Electrical Structure of head Unit HU

Fig. 4 is a diagram showing an electrical structure of the head unit HU. As described above, as shown in fig. 4, the head unit HU is connected to the cable 60, and has the recording head HD, the supply circuit 70, and the limiting circuit 80.

The cable 60 includes a plurality of wires 61-68. The wiring 61 is an example of a first wiring. The wiring 61 of the present embodiment is a power supply line on the high potential side of a fixed potential, i.e., the power supply potential VHV. The power supply potential VHV is used to drive the ejection section D. The wiring 62 is an example of a second wiring. The wiring 62 of the present embodiment is a signal line for transmitting a LAT signal, which is an example of a pulse signal for defining the ejection timing of ink in the ejection section D. The wiring 63 is a signal line for transmitting the drive signal Com. The wiring 64 is a signal line for transmitting the print signal SI. The wiring 65 is a signal line that transmits the clock signal CLK. The wiring 66 is a signal line for transmitting the change signal CNG. The wiring 67 is a power supply line for supplying the offset potential VBS. The wiring 68 is a low-potential-side power supply line for supplying the power supply potential VDD. The power supply potential VDD is used to drive various logic circuits within the head unit HU. Although not shown, the cable 60 includes a ground potential 0V wiring serving as a reference potential in addition to the above-described wiring.

The supply circuit 70 has M switches SW (SW 1 to SW M) and a connection state specifying circuit 71 for specifying the connection state of each switch SW. In fig. 4, for convenience of explanation, a case where M is 3 is shown.

The switch SW [ m ] is a switch for switching conduction (on) and non-conduction (off) between the wiring 63 and the piezoelectric element PZ [ m ] in a transmission path for transmitting the drive signal Com from the drive signal generation circuit 54 to the piezoelectric element PZ [ m ]. Each switch SW is, for example, a transmission gate.

The connection state specifying circuit 71 generates connection state specifying signals SL [1] to SL [ M ] for specifying on and off of the switches SW [1] to SW [ M ] based on the clock signal CLK, the print signal SI, the latch signal LAT, and the change signal CNG supplied from the control circuit 51. Here, the latch signal LAT is an example of a pulse signal that defines the ejection timing of the ink in the ejection portion D.

More specifically, the connection state specifying circuit 71 includes transmission circuits SR [1] SR [ M ], latch circuits LT [1] LT [ M ], and decoders DC [1] DC [ M ] in one-to-one correspondence with the ejection sections D [1] D [ M ]. The print signal SI is supplied to the transmission circuit SR [ m ] through the wiring 64. Here, the individual specification signal Sd [ m ] described later is included in the print signal SI. In the example shown in fig. 4, the individual specification signals Sd [1] to Sd [ M ] are supplied in series, and for example, the individual specification signals Sd [ M ] are sequentially transmitted from the transmission circuit SR [1] to the transmission circuit SR [ M ] in synchronization with the clock signal CLK from the wiring 65. The latch circuit LT [ m ] latches the individual specification signal Sd [ m ] supplied to the transmission circuit SR [ m ] at the timing when the pulse PlsL of the latch signal LAT from the wiring 62 rises to the high level. The decoder DC [ m ] generates the connection state specifying signal SL [ m ] based on the individual specifying signal Sd [ m ], the latch signal LAT, and the change signal CNG. Here, the power supply potential VHV is also used to generate the connection state designation signal SL [ m ] in the decoder DC [ m ].

The switch SW m is switched on and off in accordance with the connection state specifying signal SL m generated as described above. For example, when the connection state designating signal SL [ m ] is high level, the switch SW [ m ] is turned on, and when it is low level, the switch SW [ m ] is turned off. As described above, the supply circuit 70 supplies a part or all of the waveform included in the drive signal Com to one or more discharge units D selected from the plurality of discharge units D as the supply drive signal Vin.

When a damage of the wiring in the cable 60 is detected, the limiting circuit 80 limits the ejection of the ink in the recording head HD. Specifically, the limiting circuit 80 includes a first counter 81, a second counter 82, an ejection limiting section 83, and a storage circuit 84.

The first counter 81 is a circuit whose count value changes based on a potential change in the wiring 61. Therefore, the first counter 81 outputs a count value that changes each time the potential in the wiring 61 is lower than the lower limit value that is the range allowed by the original power supply potential VHV. Specifically, the first counter 81 is electrically connected to the wiring 61, and outputs a count value that counts up each time the potential in the wiring 61 becomes smaller than a predetermined first count threshold. The first count threshold is the lower limit value or a value smaller than the lower limit value, and is set to an arbitrary value between 0V and a set value of the power supply potential VHV, for example, as appropriate. Further, the first counter 81 may output a count value that counts down each time the potential in the wiring 61 becomes smaller than the first count threshold.

The second counter 82 is a circuit whose count value changes based on a potential change in the wiring 62. Therefore, the second counter 82 outputs a count value that changes in accordance with the number of pulses of the latch signal LAT. Specifically, the second counter 82 is electrically connected to the wiring 62, and outputs a count value that counts up each time the potential in the wiring 62 exceeds a predetermined second count threshold. The second count threshold is set to an arbitrary value between a high level and a low level in the latch signal LAT, for example, as appropriate. Here, the second counter 82 counts the number of pulse rising edges in the latch signal LAT. Further, the second counter 82 may also count the number of pulse falling edges in the latch signal LAT. The second counter 82 may output a count value that counts down each time the potential in the wiring 62 exceeds the second count threshold.

The ejection regulating section 83 is a circuit for regulating the ink ejection operation in the ejection section D based on the count value of the first counter 81 and the count value of the second counter 82. As will be described in detail later, the ejection limiting section 83 of the present embodiment limits the ejection action of the ink in the ejection section D based on the ratio between the amount of change in the count value of the first counter 81 and the amount of change in the count value of the second counter 82 in a predetermined period, i.e., the determination period Td. When the ratio satisfies a predetermined condition, for example, the ejection limiting section 83 stops the operation of the connection state specifying circuit 71 so that the switch SW [ m ] is kept in the off state. Further, the ejection limiting section 83 may also include a programmable logic device such as an FPGA.

The storage circuit 84 is a circuit for storing information necessary for the operation of the ejection regulating section 83. The memory circuit 84 includes, for example, a semiconductor memory. The storage circuit 84 of the present embodiment stores period designation information D1 and threshold information D2. The period specification information D1 is information for specifying the determination period Td in the ejection limiting section 83. The period specifying information D1 of the present embodiment is information relating to the count value of the second counter 82. The threshold information D2 is information relating to a threshold as a reference for determining whether or not the wiring 61 is damaged. The threshold information D2 in the present embodiment is information related to the count value of the first counter 81. A part or the whole of the memory circuit 84 may be included in the ejection limiting section 83.

A1-5. action of head Unit HU

Fig. 5 is a timing chart for explaining an example of the operation of the head unit HU. As shown in fig. 5, the latch signal LAT includes a pulse PlsL for specifying the unit period Tu. The unit period Tu is defined as a period from the rising edge of the pulse PlsL to the rising edge of the next pulse PlsL, for example. In addition, the change signal CNG includes a pulse PlsC for distinguishing the unit period Tu into the control period Tu1 and the control period Tu 2. The control period Tu1 is, for example, a period from the rising edge of the pulse PlsL to the rising edge of the pulse PlsC. The control period Tu2 is, for example, a period from the rising edge of the pulse PlsC to the rising edge of the pulse PlsL.

The print signal SI includes individual specification signals Sd [1] to Sd [ M ] for specifying operation types of the ejection sections D [1] to D [ M ] in each unit period Tu. Before the unit period Tu, as described above, the individual specification signals Sd [1] to Sd [ M ] are supplied to the connection state specifying circuit 11 in synchronization with the clock signal CLK. The connection state specifying circuit 11 generates the connection state specifying signal SL [ m ] based on the individual specifying signal Sd [ m ] in the unit period Tu.

As shown in fig. 5, the drive signal Com has the waveform PX set in the control period Tu1 and the waveform PY set in the control period Tu 2. In the example shown in fig. 5, the potential difference between the highest potential VHX and the lowest potential VLX in the waveform PX is larger than the potential difference between the highest potential VHY and the lowest potential VLY in the waveform PY.

When the individual designation signal Sd [ m ] is a value shaped to the midpoint, the connection state designation signal SL [ m ] is at the high level in the control period Tu1 and at the low level in the control period Tu 2. Therefore, only the waveform PX of the drive signal Com is supplied to the discharge unit D as the supply drive signal Vin. As a result, an ink amount corresponding to the midpoint is ejected from the ejection portion D.

When the individual designation signal Sd [ m ] is a value shaped to a small dot, the connection state designation signal SL [ m ] is at a low level in the control period Tu1 and at a high level in the control period Tu 2. Therefore, only the waveform PY of the drive signal Com is supplied to the ejection section D as the supply drive signal Vin. As a result, an amount of ink corresponding to the small dot is discharged from the discharge portion D.

When the individual designation signal Sd [ m ] is a value shaped to a large dot, the connection state designation signal SL [ m ] is high level in both of the control periods Tu1 and Tu 2. Accordingly, the waveforms PX and PY in the drive signal Com are supplied to the ejection section D as the supply drive signal Vin. As a result, an amount of ink corresponding to the large dot is discharged from the discharge portion D.

When the individual specification signal Sd [ m ] is a value that specifies that ink is not ejected, the connection state specification signal SL [ m ] is low in both of the control periods Tu1 and Tu 2. Therefore, neither of the waveforms PX and PY in the drive signal Com is supplied to the discharge portion D. As a result, the ink is not ejected from the ejection section D.

A1-6 operation of the ejection regulating part 83

Fig. 6 is a diagram for explaining the determination period Td of the ejection limiting section 83 in the first embodiment. A relationship between the potential V1 of the wiring 61, the potential V2 of the wiring 62, and the determination period Td is shown in fig. 6. The ejection limiting section 83 limits the ink ejection operation in the ejection section D based on the ratio between the amount of change in the count value of the first counter 81 and the amount of change in the count value of the second counter 82 in the determination period Td.

As shown in fig. 6, the determination period Td of the present embodiment is specified by the number of pulses PlsL of the latch signal LAT. In fig. 6, a case where the determination period Td is defined by n pulses PlsL _1 to PlsL _ n is shown. N in the present embodiment is a natural number of 2 or more. In this manner, the determination period Td in the present embodiment is a period in which the amount of change in the count value of the second counter 82 becomes the predetermined amount n.

Fig. 6 shows a case where the potential V1 has p fluctuations FL _1 to FL _ p within the determination period Td, the potentials of the p fluctuations FL _1 to FL _ p being lower than the first count threshold value of the first counter 81. The greater the amount of change in the count value of the first counter 81 in the determination period Td, the higher the possibility of damage to the wiring 61.

The count value of the first counter 81 changes when the wiring 61 is damaged, but also changes when the voltage value of the commercial power supply fluctuates. Therefore, if an attempt is made to detect damage to the wiring 61 based only on the count value of the first counter 81, damage may be erroneously detected when a fluctuation or the like occurs in the voltage value of the commercial power supply.

Examples of the damaged state of the wiring 61 include a state in which a part of the wiring 61 is missing, and a state in which portions of the wiring 61 separated by disconnection may come into contact with each other. When the wiring 61 or 62 is completely disconnected, no power or signal is supplied to the ejection unit D, and therefore ink cannot be ejected from the ejection unit D.

On the other hand, the second counter 82 outputs a count value that changes based on a change in displacement of the wiring 62 included in the same cable 60 as the wiring 61. Therefore, when the count value of the first counter 81 changes and the count value of the second counter 82 also changes, since the wiring 62 is not damaged, it can be presumed that the wiring 61 is also not damaged. Here, since the potential of the latch signal LAT is much lower than the power supply potential VHV, the latch signal LAT is generated with little problem when the voltage value of the commercial power supply fluctuates. In contrast, when the count value of the first counter 81 is changed and the count value of the second counter 82 is not changed, the possibility that the wiring 62 is damaged is high, and it can be estimated that the wiring 61 is damaged.

Thus, the discharge limiting section 83 determines whether or not the amount of change in the count value of the first counter 81 exceeds the threshold value within the determination period Td. When the count value of the second counter 82 reaches a predetermined value, the ejection limiting unit 83 of the present embodiment performs this determination. Then, when the amount of change in the count value of the first counter 81 in the determination period Td exceeds the threshold value, the ejection limiting section 83 limits the ink ejection operation in the ejection section D. On the other hand, when the amount of change in the count value of the first counter 81 in the determination period Td is equal to or less than the threshold, the ejection regulating section 83 does not regulate the ink ejection operation in the ejection section D.

From the viewpoint of accurately determining damage to the wiring 61, the predetermined value, that is, the number n of pulses PlsL of the predetermined determination period Td is preferably in the range of 100 to 10000, more preferably in the range of 500 to 3000, and even more preferably in the range of 700 to 2000. On the other hand, if the number n is too small or too large, the false detection wiring 61 tends to be damaged.

From the same viewpoint, the threshold value, i.e., the number p of damages of the wiring 61, is preferably 2 or more, and more preferably in the range of 2 or more and 5 or less.

Fig. 7 is a flowchart for explaining the operation of the ejection limiting section 83 in the first embodiment. As shown in fig. 7, first, in step S100, the ejection limiting section 83 resets the first counter 81 and the second counter 82. Next, in step S110, the ejection limiting portion 83 determines whether the count value of the second counter 82 has reached a predetermined value based on the above-described period specification information D1. This step S110 is repeated until the count value of the second counter 82 reaches a predetermined value.

When the count value of the second counter 82 has reached the predetermined value, the ejection limiting section 83 determines whether or not the count value of the first counter 81 exceeds the threshold value based on the threshold value information D2 in step S120. When the count value of the first counter 81 is equal to or less than the threshold value, the process returns to step S100. On the other hand, when the count value of the first counter 81 exceeds the threshold value, the ejection regulating section 83 regulates the ink ejection operation in the ejection section D in step S130.

As described above, the liquid ejecting apparatus 1 described above includes the power supply circuit 53 and the head unit HU as an example of the liquid ejecting head unit. Here, the head unit HU includes the discharge portion D, the wiring 61 as an example of the first wiring, the wiring 62 as an example of the second wiring, the first counter 81, the second counter 82, and the discharge limiting portion 83.

In the head unit HU, the ejection portion D ejects ink as an example of liquid. The wiring 61 is a wiring for supplying a power supply potential VHV as an example of a fixed potential for driving the ejection section D. The power supply potential VHV is supplied to the wiring 61 by using electric power supplied from a commercial power supply not shown. The wiring 62 transmits a latch signal LAT as an example of a pulse signal that defines the ejection timing of the ink in the ejection portion D. The count value of the first counter 81 changes according to the potential change in the wiring 61. The count value of the second counter 82 changes according to the potential change in the wiring 62. The ejection regulating section 83 regulates the ink ejection operation in the ejection section D based on the count value of the first counter 81 and the count value of the second counter 82.

Therefore, compared with the conventional structure in which the ejection action of the liquid in the ejection section D is limited based only on the count value of the first counter 81, it is possible to detect the wiring damage of the wiring 61 with high accuracy and to limit the ejection action of the ink in the ejection section D. That is, in the conventional configuration, the fluctuation of the voltage value of the commercial power supply or the like is erroneously detected as the damage of the wiring 61, and the ink discharge operation in the discharge portion D is unnecessarily restricted based on the erroneous detection, whereas in the head unit HU, the unnecessary restriction of the ink discharge operation in the discharge portion D based on the erroneous detection is reduced as compared with the conventional configuration.

Further, by using the conventional latch signal LAT as a pulse signal for specifying the ejection timing of the ink in the ejection portion D, the circuit configuration of the ejection regulating portion 83 is not complicated as compared with the conventional one. The latch signal LAT is less susceptible to fluctuations in the voltage value of the commercial power supply than the power supply potential VHV. Therefore, the state of the potential fluctuation of the power supply potential VHV can be detected with high accuracy using the potential fluctuation of the latch signal LAT as a reference. As a result, it is effectively reduced that the voltage value fluctuation of the commercial power supply or the like is erroneously detected as damage to the wiring 61.

The head unit HU of the present embodiment is mounted on a serial printer and used. That is, the liquid ejecting apparatus 1 includes a housing 10 to which a power supply circuit 53 is fixed, a carriage 20 that reciprocates in a predetermined direction with respect to the housing 10, and a cable 60 that is a flexible flat cable connecting the power supply circuit 53 and the carriage 20. Here, the discharge portion D is mounted on the carriage 20. The cable 60 includes wires 61 and 62. Therefore, if the carriage 20 is repeatedly reciprocated relative to the housing 10, since the wiring 61 included in the cable 60 is repeatedly deformed, the risk of damage to the wiring 61 is high. Therefore, when the head unit HU is mounted on the serial printer, it is useful to restrict the operation of the ejection section D when damage to the wiring 61 is detected.

A2. Second embodiment

Fig. 8 is a diagram for explaining the determination period Td of the ejection limiting section 83 in the second embodiment. As shown in fig. 8, the ejection limiting unit 83 according to the second embodiment defines a determination period Td by the count value of the first counter 81, and determines whether or not the ratio of the count values in the determination period Td satisfies a predetermined condition by whether or not the count value of the second counter 82 is smaller than a threshold value. Further, the period specification information D1 of the present embodiment is information relating to the count value of the first counter 81. The threshold information D2 in the present embodiment is information related to the count value of the second counter 82.

As shown in fig. 8, the determination period Td of the present embodiment is defined by the number p of fluctuations FL of the power supply potential VHV. Fig. 8 shows a case where the determination period Td is defined by p fluctuations FL _1 to FL _ p. In this manner, the determination period Td in the present embodiment is a period in which the amount of change in the count value of the first counter 81 becomes the predetermined amount p.

When the count value of the first counter 81 has reached the predetermined value, the ejection limiting section 83 of the present embodiment determines whether or not the amount of change in the count value of the second counter 82 within the determination period Td is smaller than the threshold value. When the amount of change in the count value of the second counter 82 in the determination period Td is smaller than the threshold value, the ejection limiting section 83 limits the ink ejection operation in the ejection section D. On the other hand, when the amount of change in the count value of the second counter 82 in the determination period Td is equal to or greater than the threshold, the ejection regulating section 83 does not regulate the ink ejection operation in the ejection section D.

From the viewpoint of accurately determining damage to the wiring 61, the above-described predetermined value, that is, the number p of fluctuations FL of the prescribed determination period Td is preferably within a range of 2 or more and 5 or less. From the same viewpoint, the threshold value, i.e., the number n of damages determined to the wiring 61, is preferably in the range of 100 to 10000, more preferably 500 to 3000, and even more preferably 700 to 2000.

Fig. 9 is a flowchart for explaining the operation of the ejection limiting section 83 in the second embodiment. As shown in fig. 9, first, in step S100, the ejection limiting section 83 resets the first counter 81 and the second counter 82. Next, in step S140, the ejection limiting portion 83 determines whether the count value of the first counter 81 has reached a predetermined value based on the above-described period specification information D1. This step S140 is repeated until the count value of the first counter 81 reaches a predetermined value.

When the count value of the first counter 81 has reached the predetermined value, the ejection limiting section 83 determines whether or not the count value of the second counter 82 is smaller than the threshold value based on the threshold value information D2 in step S150. When the count value of the second counter 82 is equal to or greater than the threshold value, the process returns to step S100. On the other hand, when the count value of the second counter 82 is smaller than the threshold value, the ejection regulating section 83 regulates the ink ejection operation in the ejection section D in step S130.

The second embodiment described above can also provide the same effects as those of the first embodiment described above. In the present embodiment, since the number of fluctuations FL within the determination period Td is fixed, there is an advantage that the driving of the ejection portion D is reduced in a state of the unstable power supply potential VHV as compared with the above-described first embodiment. In addition, reducing the driving of the ejection portion D in the state of the unstable power supply potential VHV also contributes to reducing the risk of failure of the head unit HU.

B. Modification example

Various modifications may be made to the embodiments described above. Specific modifications will be exemplified below. Two or more modes arbitrarily selected from the following examples may be appropriately combined within a range not contradictory to each other. In addition, in the modification shown below, for elements having the same actions and functions as those of the embodiment, the symbols referred to in the above description will be used, and detailed description of each element will be appropriately omitted.

B1. Modification example 1

The determination period Td in each of the above embodiments is not limited to a period based on the count value of the first counter 81 or the second counter 82, and may be a period determined according to the predetermined number of pulses of the clock signal CLK, for example.

Fig. 10 is a diagram for explaining the determination period Td of the ejection limiting section 83 in the modification 1. In modification 1, as shown in fig. 10, the determination period Td is a fixed period set in advance. The determination period Td in modification 1 is defined by, for example, the number of pulses of the clock signal CLK. Further, the ejection limiting section 83 of modification 1 determines, for each determination period Td, whether or not the ratio between the count value of the first counter 81 and the count value of the second counter 82 in the determination period Td satisfies a predetermined condition. Further, the period specification information D1 of the present embodiment is information relating to the number of pulses of the clock signal CLK. The threshold information D2 of the present embodiment is information relating to the ratio between the count value of the first counter 81 and the count value of the second counter 82.

Fig. 11 is a flowchart for explaining the operation of the ejection regulating section 83 in modification 1. As shown in fig. 11, first, in step S100, the ejection limiting section 83 resets the first counter 81 and the second counter 82. Next, in step S160, the ejection limiting section 83 determines whether or not a predetermined time has elapsed based on the predetermined number of pulses of the clock signal CLK. This step S160 is repeated until a predetermined time elapses.

When the predetermined time has elapsed, in step S160, the ejection limiting portion 83 determines whether or not the ratio of the count value of the first counter 81 to the count value of the second counter 82 exceeds the threshold value based on the threshold value information D2 described above within the period of the predetermined time. When the ratio is equal to or lower than the threshold value, the process returns to step S100. On the other hand, when the ratio exceeds the threshold value, the ejection regulating section 83 regulates the ink ejection operation in the ejection section D in step S130.

B2. Modification 2

The fixed potential supplied to the first wiring is not limited to the power supply potential VHV, and may be, for example, an offset potential VBS. The pulse signal transmitted to the second wiring is not limited to the latch signal LAT, and may be, for example, a print signal SI, a clock signal CLK, a change signal CNG, or the like.

B3. Modification 3

In the above-described embodiment and modification, the liquid ejection device 1 has one drive signal generation circuit 54 and one head unit HU, but the present invention is not limited thereto, and the liquid ejection device 1 may have a plurality of drive signal generation circuits 54 or a plurality of head units HU.

B4. Modification example 4

In the above-described embodiment and modification, the liquid discharge device 1 is assumed to be a serial printer, but the present invention is not limited to this, and the liquid discharge device 1 may be a so-called line printer in which a plurality of nozzles N are provided in the recording head HD so as to extend wider than the width of the printing medium P.

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