Liquid dispensing head and liquid dispensing device

Abstract

The liquid circulation flow rate must be appropriately controlled. [Solution] The liquid discharge head includes a circulation channel through which liquid can circulate, a discharge unit that discharges the liquid circulating in the circulation channel, a circulation pump that circulates the liquid in the circulation channel, a pump driving means that drives the circulation pump based on capability information that can be set by the components of the circulation pump, a head board on which the function of the pump driving means is implemented, and a storage means that is implemented on the head board and stores the capability information. The capability information is an indicator of the ability to circulate the liquid in the circulation channel.

Description

Technical Field

[0001] The present disclosure relates to the control of the circulation flow rate of ink.

Background Art

[0002] In the field of inkjet printers in recent years, an ink circulation type liquid ejection device has been demanded. Further, Patent Document 1 discloses a technique for continuously circulating ink (hereinafter also referred to as a liquid) by continuously adjusting the drive voltages of a supply pump and a recovery pump so that the nozzle pressure of an inkjet head becomes a target pressure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, due to manufacturing variations in the liquid ejection device, the circulation flow rate of the liquid may not be stable, and there may be cases where the circulation flow rate of the liquid cannot be appropriately controlled as needed.

Means for Solving the Problems

[0005] A liquid ejection head according to an aspect of the present disclosure includes a discharge unit that discharges a liquid circulating in the circulation flow path, a circulation pump that circulates the liquid in the circulation flow path, pump drive means for driving the circulation pump based on ability information that can be set by components of the circulation pump, a head substrate on which the function of the pump drive means is implemented, and storage means that is mounted on the head substrate and stores the ability information, and the ability information is an index of the ability to circulate a liquid in the circulation flow path.

Effects of the Invention

[0006] According to this disclosure, the circulation flow rate of the liquid can be appropriately controlled as needed. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows a schematic configuration example of a liquid dispensing device in the first embodiment. [Figure 2] This figure shows an example of the hardware configuration of the liquid dispensing device in Figure 1 in the first embodiment. [Figure 3] This is an exploded perspective view of the liquid dispensing head in Figure 1 in the first embodiment. [Figure 4] This is a schematic diagram of the external appearance of the ink circulation unit in Figure 3 in the first embodiment. [Figure 5] This is a schematic diagram of the circulation path in the liquid discharge head shown in Figure 1 in the first embodiment. [Figure 6] This figure shows an example of the wiring of the circulation pump in Figure 5 in the first embodiment. [Figure 7] This is a schematic cross-sectional view of the circulation pump in Figure 6 in the first embodiment. [Figure 8] This figure shows a schematic example of the configuration of the pump drive circuit that drives the circulation pump shown in Figure 7 in the first embodiment. [Figure 9] This figure shows an example of the circuit configuration of the boost circuit in Figure 8 in the first embodiment. [Figure 10] This figure shows an example of the circuit configuration of the output switching circuit in the first embodiment shown in Figure 8. [Figure 11] This is a timing chart of the control signals that control the pump drive circuit in Figure 8 in the first embodiment. [Figure 12] This is a table showing the relationship between the capacitance of a piezoelectric element provided in the circulation pump in the first embodiment and the pump drive frequency. [Figure 13] This is a table showing the relationship between the thickness of the diaphragm provided in the circulation pump in the second embodiment and the pump drive frequency. [Figure 14]A table showing the correspondence between the thickness of the valve body of the diaphragm unit provided in the circulation pump in the third embodiment and the pump drive frequency. [Figure 15] A table showing the ranks corresponding to the capacitance of the piezoelectric element, the diaphragm thickness of the diaphragm, and the diaphragm valve thickness of the valve body provided in the circulation pump in the fourth embodiment. [Figure 16] A table showing the correspondence between the total value of the ranks in the fourth embodiment and the pump drive frequency. [Figure 17] A table showing the correspondence between the capacitance of the piezoelectric element provided in the circulation pump in the fifth embodiment and the pump drive voltage. [Figure 18] A timing chart of the control signal for controlling the pump drive circuit in the sixth embodiment. [Figure 19] A table showing the correspondence between the capacitance of the piezoelectric element provided in the circulation pump in the sixth embodiment and the pump drive pulse width. [Figure 20] A diagram showing a schematic example of the configuration of the pump drive circuit for driving the circulation pump in the seventh embodiment. [Figure 21] A diagram showing a schematic example of the configuration of the pump drive circuit for driving the circulation pump in the eighth embodiment.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present disclosure, and not all combinations of the features described in the following embodiments are essential for the solution means of the present disclosure. The same reference numerals are assigned to the same components

[0009] (Overview) In recent years, in the field of inkjet printers, there has been a demand for an ink circulation type liquid ejection device that can handle special inks according to the ejected medium for outputting high-quality printed materials. As such an ink circulation type liquid ejection device, a configuration has been proposed in which a liquid supply path and a recovery path are provided, and a differential pressure is generated between the supply path and the recovery path so that the liquid can be circulated. Also, as one configuration in which the liquid can be circulated, a liquid circulation device that circulates the liquid by the operation of a piezoelectric diaphragm has been disclosed. This liquid circulation device includes a supply pump, a recovery pump, and a pump control unit. The supply pump supplies the liquid from the liquid storage container toward the liquid ejection device by the operation of the piezoelectric diaphragm. The recovery pump recovers the liquid from the liquid ejection device and returns it to the liquid storage container by the operation of the piezoelectric diaphragm. The pump control unit controls each of the supply pump and the recovery pump. Specifically, the pump control unit controls the operation of the piezoelectric diaphragm by adjusting the voltage or frequency of the drive wave of the supply pump or the recovery pump so that the nozzle pressure of the inkjet becomes the target pressure, and the supply and recovery of the liquid are performed. Thus, by performing the supply and recovery of the liquid, the liquid can be circulated.

[0010] However, even if the above operation is performed, the circulation flow rate of the liquid may not be appropriately controlled. For example, a phenomenon may occur in which the ejection performance of the liquid ejection head deteriorates due to evaporation of moisture from the liquid ejection port in the liquid ejection head. To avoid this phenomenon, a liquid circulation operation is performed in which the liquid with evaporated moisture is recovered near the ejection port and the liquid with less moisture evaporation is supplied. That is, a circulation flow rate of a certain level or more is desirable to reduce the moisture evaporation of the liquid near the ejection port.

[0011] On the other hand, the temperature difference between the liquid in the liquid discharge head and the liquid in the liquid reservoir can cause a temperature distribution within the liquid discharge head where the liquid circulation flow rate differs between areas with high and low flow rates. When such a temperature distribution occurs, the viscosity of the liquid changes with temperature, resulting in uneven concentration of the liquid discharged from the liquid discharge head. Therefore, the temperature distribution within the liquid discharge head can be a factor in uneven concentration during liquid discharge recording. In other words, from the viewpoint of image quality, it is desirable to suppress the circulation flow rate to below a certain level in order to avoid the occurrence of temperature distributions with different temperatures.

[0012] Furthermore, temperature control of the liquid discharge head is a power-consuming control mechanism. For example, as the liquid circulation flow rate within the liquid discharge head increases, the power required to maintain the liquid's temperature also increases. In other words, from the standpoint of reducing power consumption, it is desirable to keep the liquid circulation flow rate below a certain level.

[0013] Therefore, a liquid dispensing device capable of appropriately controlling the liquid circulation flow rate is desired. However, due to manufacturing variations in liquid dispensing devices, particularly in circulation pumps, the liquid circulation flow rate was sometimes unstable, making it impossible to appropriately control the liquid circulation flow rate.

[0014] Therefore, the liquid dispensing device in this disclosure comprises a circulation channel, a dispensing unit, a circulation pump, a pump driving means, a head board, and a storage means. The circulation channel is a channel through which liquid can circulate. The dispensing unit dispensing the liquid circulating in the circulation channel. The circulation pump circulates the liquid in the circulation channel. The pump driving means drives the circulation pump based on capability information that can be set by the components of the circulation pump. The head board implements the functions of the pump driving means. The storage means is mounted on the head board and stores the capability information. The capability information is an indicator of the capacity to circulate the liquid in the circulation channel. With this configuration, even if there are manufacturing variations in the liquid dispensing device, particularly the circulation pump, the circulation pump is driven based on capability information that can be set by the components of the circulation pump. Therefore, the liquid circulation flow rate is stable, and the liquid circulation flow rate can be appropriately controlled as needed. For example, it is possible to decrease the liquid circulation flow rate when it increases, and to increase it when it decreases. Therefore, it is possible to appropriately achieve both the reduction of power consumption and the reduction of water evaporation, thereby achieving overall compatibility. Further details of this disclosure will be explained below.

[0015] (First embodiment) (Common configuration for each embodiment) Figure 1 is a diagram showing a schematic configuration example of a liquid dispensing device 50 in the first embodiment. Figure 1(a) is a schematic perspective view of the liquid dispensing device 50. Figure 1(b) is a block diagram of the control system of the liquid dispensing device 50 in Figure 1(a). The liquid dispensing device 50 comprises a liquid dispensing head 1 and transport rollers 55, 56, 57, and 58. The liquid dispensing head 1 is scannable in a direction X that intersects the transport direction Y of the medium to be dispensed P. In the example in Figure 1(a), the liquid dispensing head 1 is mounted on a carriage 53. The carriage 53 reciprocates along the guide axis 51 in the main scanning direction (also referred to as direction X). The transport rollers 55, 56, 57, and 58 transport the medium to be dispensed P in a sub-scanning direction (also referred to as transport direction Y) that intersects (orthogonal in this example) the main scanning direction. In other words, the liquid ejection device 50 constitutes a serial-type inkjet liquid ejection device by ejecting liquid from the liquid ejection head 1 onto the ejection medium P being transported in the transport direction Y while scanning the liquid ejection head 1 in direction X. However, the application of this disclosure is not limited to serial-type inkjet liquid ejection devices. This disclosure can also be applied to a page-wide type inkjet liquid ejection device that ejects liquid onto the ejection medium P being transported in the transport direction Y by using a line head (page-wide type head) that is long in the page width direction of the ejection medium P. In Figure 1(a), direction Z indicates the vertical direction. That is, direction Z is the direction that intersects (orthogonal in this example) the XY plane specified by direction X and transport direction Y. In the following explanation, direction X, transport direction Y, and direction Z will be used with the same meaning as described above.

[0016] The liquid ejection head 1 is capable of ejecting four types of ink: black (K), cyan (C), magenta (M), and yellow (Y). The liquid ejection head 1 can eject a full-color image using these four types of ink. However, the inks that can be ejected from the liquid ejection head 1 are not limited to the above four types. For example, this disclosure is also applicable to a liquid ejection head 1 for ejecting other types of ink, such as spot color inks. That is, the type and number of inks ejected from the liquid ejection head 1 are not limited. Furthermore, a cap member may be positioned to cover the face surface of the liquid ejection head 1, away from the transport path of the ejection medium P. When not performing a recording operation, the cap member moves relative to the position that covers the face surface of the liquid ejection head 1. This operation prevents the liquid ejection port of the liquid ejection head 1 from drying out, or allows for suction operations for filling or restoring.

[0017] In the example shown in Figure 1(a), an ink circulation unit 54 is mounted on the liquid ejection head 1. A guide 59 housing four ink supply tubes (liquid passages) is attached to the ink circulation unit 54. In addition to the ink supply tubes, the guide 59 also houses the electrical wiring and air piping necessary for liquid ejection. Furthermore, an ink tank 2 and a pump 21 are provided on the main body (not shown) side of the liquid ejection device 50. The ink tank 2 stores ink. The ink stored in the ink tank 2 is supplied to the ink circulation unit 54 via the four ink supply tubes by the driving force of the pump 21. The liquid ejection head 1 may be provided integrally with the ink circulation unit 54 and configured to be removable or attachable to the carriage 53. Alternatively, the ink circulation unit 54 may be provided integrally with the carriage 53, and only the ink circulation unit 54 may be configured to be removable or attachable. In the following description, an example in which the liquid ejection head 1 includes the ink circulation unit 54 will be described.

[0018] The CPU 400 in Figure 1(b) controls various aspects of the liquid dispensing device 50. ROM 401 stores programs such as processing procedures. The CPU 400 retrieves these programs from ROM 401. Based on the programs retrieved from ROM 401, the CPU 400 controls the liquid dispensing device 50. The CPU 400 uses RAM 402 as a work area for executing the programs retrieved from ROM 401. The CPU 400 retrieves image data from a host device 500 located outside the liquid dispensing device 50. Based on the image data retrieved from the host device 500, the CPU 400 controls the head driver 1A. The head driver 1A controls the liquid dispensing by the liquid dispensing head 1. The CPU 400 also controls the motor driver 403A. The motor driver 403A controls the carriage motor 403. The carriage motor 403 moves the carriage 53 along the X direction. The CPU 400 also controls the motor driver 404A. The motor driver 404A controls the transport motor 404. The transport motor 404 controls the transport rollers 55, 56, 57, and 58. The transport rollers 55, 56, 57, and 58 transport the medium to be discharged P along the transport direction Y.

[0019] (Hardware configuration) Figure 2 shows an example of the hardware configuration of the liquid dispensing device 50 in Figure 1 in the first embodiment. The liquid dispensing device 50 includes a control IC 40 and a drive circuit 40A as control elements for the liquid dispensing head 1. The control IC 40 in Figure 2 includes, for example, the CPU 400, ROM 401, and RAM 402 in Figure 1(b). The drive circuit 40A in Figure 2 includes, for example, the head driver 1A, motor driver 403A, and motor driver 404A in Figure 1(b). The liquid dispensing head 1 in Figure 2 includes an EEPROM 427, a circulation pump 27, a first regulator 24, a second regulator 28, and a dispensing module 302. As will be described in detail later, capability information is stored in the EEPROM 427. Capability information can be set by the components of the circulation pump 27 as an indicator of the ability to circulate liquid in the circulation path. The circulation path, as will be described later using Figure 5, consists of a path that passes through the circulation pump 27, the first regulator 24, the dispensing module 302, and the second regulator 28. The control IC 40 generates a control signal based on capability information supplied from the EEPROM 427. The drive circuit 40A generates a drive signal based on the control signal generated by the control IC 40. The circulation pump 27 controls the circulation flow rate of the liquid flowing through the circulation channel based on the drive signal generated by the drive circuit 40A. The liquid circulating through the circulation channel is supplied from the ink tank 2. That is, the circulation pump 27 controls the circulation flow rate of the ink stored in the ink tank 2.

[0020] (Liquid dispensing head 1) Figure 3 is an exploded perspective view of the liquid discharge head 1 of Figure 1 in the first embodiment. The liquid discharge head 1 comprises a flow channel member 110, an ink circulation unit 54, and a discharge unit 300. At least a portion of the ink circulation unit 54 is housed in the flow channel member 110 and connected to the flow channel member 110. The discharge unit 300 is provided at the bottom of the flow channel member 110 and connected to the flow channel member 110. Specifically, the ink circulation unit 54 consists of ink circulation units 54m, 54y, 54k, and 54c, each corresponding to a different ink. When not specifically distinguishing between the ink circulation units 54m, 54y, 54k, and 54c, they are referred to as the ink circulation unit 54. Each ink circulation unit 54 is housed in and connected to the flow channel member 110. Each ink circulation unit 54 and the flow channel member 110 may be connected by screw fastening with a sealing member sandwiched between them. Alternatively, each ink circulation unit 54 and the flow path member 110 may be connected by welding. The flow path member 110 has a surface on which four joints 200 are connected to each of the four ink supply tubes corresponding to the four types of ink. That is, a separate ink supply path is provided for each type of ink. Specifically, each of the ink circulation units 54m, 54y, 54k, and 54c is connected to each of the ink supply tubes corresponding to each ink from the main body side of the liquid discharge device 50 via its respective joint 200. Each ink supplied from the respective corresponding ink supply tube is supplied to each ink circulation unit 54 via the joint 200. Each ink supplied to each ink circulation unit 54 is supplied to the discharge unit 300 via the flow path member 110.

[0021] The ejection unit 300 comprises an ejection element substrate 310, a support member 320, an electrical wiring board 330, and a cover member 340. The ejection element substrate 310 and the electrical wiring board 330 are bonded and fixed to the support member 320. The cover member 340 is bonded and joined to cover the surface of the electrical wiring board 330. The portion of the cover member 340 corresponding to the ejection element substrate 310 is open. The ejection element substrate 310 has an actuator for ejecting ink. Therefore, the ejection element substrate 310 can eject liquid into the medium P to be ejected, which passes below the liquid ejection head 1. The ejection unit 300 and the flow path member 110 are bonded together using adhesive. Alternatively, the ejection unit 300 and the flow path member 110 may be fixed together by screwing in a sealing member.

[0022] The ejection element substrate 310 and the electrical wiring board 330 are electrically connected by wire bonding. The electrical wiring board 330 sends various electrical signals to the ejection element substrate 310. The ejection element substrate 310 ejects liquid according to the various electrical signals from the electrical wiring board 330, using the drive voltage supplied from the head driver 1A. Details of the various electrical signals will be described later. Note that the ejection element substrate 310 and the electrical wiring board 330 may also be electrically connected by flying lead bonding or the like.

[0023] A contact surface is provided on the side of the flow channel member 110 opposite to the side where the joint 200 is located. The head board 210 is connected to the contact surface. The head board 210 and the flow channel member 110 may be fixed by crimping, by adhesive, or by double-sided tape. The head board 210 receives electrical signals from the main body of the liquid dispensing device 50. The head board 210 and the electrical wiring board 330 are electrically connected by ACF (Anisotropic conductive film) crimping. The head board 210 and the electrical wiring board 330 may also be electrically connected by wire bonding. Alternatively, the head board 210 and the electrical wiring board 330 may be electrically connected by flying lead bonding. The electrical signals received by the head board 210 are sent to the dispensing element board 310 via the electrical wiring board 330.

[0024] Furthermore, this disclosure works favorably even if the ink circulation unit 54 is located within the liquid ejection device but outside the liquid ejection head 1. However, in the configuration where the circulation pump 27 is located within the liquid ejection head 1, the pump capacity is limited due to the size constraints of the circulation pump 27, and therefore the effects of this disclosure are particularly obtained.

[0025] (Circulation channel) Figure 4 is a schematic diagram of the external appearance of the ink circulation unit 54 in Figure 3 in the first embodiment. One ink circulation unit 54 is provided for each color. The ink circulation unit 54 comprises a first regulator 24, a second regulator 28, a filter 23, and a circulation pump 27. Figure 5 is a schematic diagram of the circulation flow path in the liquid ejection head 1 in Figure 1 in the first embodiment. The circulation flow path in Figure 5 is for one color. The liquid ejection head 1 is provided with the circulation flow path in Figure 5 for each ink. The ink tank 2 and the pump 21 are provided on the main body side of the liquid ejection device 50. The first regulator 24 comprises a first valve chamber 25 and a first pressure control chamber 26. The first valve chamber 25 and the first pressure control chamber 26 are in communication via a valve (not shown). The second regulator 2 comprises a second valve chamber 29 and a second pressure control chamber 30. The second valve chamber 29 and the second pressure control chamber 30 are connected via a valve (not shown). The circulation pump 27 and the first pressure control chamber 26 are connected via a pump outlet passage 78. The first pressure control chamber 26 and the flow path member 110 are connected via a supply passage 75. A portion of the flow path member 110 may constitute the supply passage 75. The flow path member 110 and the second pressure control chamber 30 are connected via a recovery passage 76. A portion of the flow path member may constitute the recovery passage 76. The second pressure control chamber 30 and the circulation pump 27 are connected via a pump inlet passage 77. That is, a circulation flow path is formed consisting of the first pressure control chamber 26, the supply passage 75, the flow path member 110, the recovery passage 76, the second pressure control chamber 30, the pump inlet passage 77, the circulation pump 27, and the pump outlet passage 78. Ink can circulate through this circulation flow path. Furthermore, the flow path member 110 and the discharge unit 300 constitute a discharge module 302. Furthermore, a bypass channel 79 is provided between the first pressure control chamber 26 and the second valve chamber 29, which bypasses the ink circulation channel from the first pressure control chamber 26 to the second valve chamber 29. Details of the bypass channel 79 will be described later. Next, the details of the circulation pump 27 will be explained, followed by the flow of ink circulating through the circulation channel.

[0026] (Drive mechanism of circulation pump 27) Figure 6 shows an example of the wiring of the circulation pump 27 in Figure 5 in the first embodiment. The liquid discharge device 50 includes a main board 230, a carriage board 220, and a head board 210. The main board 230 is provided on the body of the liquid discharge device 50. The CPU 400 is mounted on the main board 230. The carriage board 220 is provided on the carriage 53. The main board 230 and the carriage board 220 are connected via an FFC (Flexible Flat Cable). A drive signal is sent from the CPU 400 to the carriage board 220 via the FFC. The carriage board 220 and the head board 210 are connected via an electrical connection part 212. A pump control signal and a pump drive reference voltage are supplied from the carriage board 220 to the head board 210 via the electrical connection part 212. The head board 210 and the circulation pump 27 are connected via a harness 211. The harness 211 consists of a cable assembly including a first wiring 211a and a second wiring 211b. A pump drive signal 608, generated based on a pump control signal 605 and a pump drive voltage 607 generated from a pump drive reference voltage 604, is supplied to the circulation pump 27 via the harness 211. The circulation pump 27 is driven based on the pump drive signal 608. The liquid in the liquid discharge head 1 circulates due to the operation of the circulation pump 27. Details of the pump control signal 605, pump drive reference voltage 604, pump drive voltage 607, and pump drive signal 608 will be described later. Note that the head board 210 and the carriage board 220 may be electrically connected by fixing them using ACF crimping. Next, the configuration of the circulation pump 27 will be described.

[0027] (Internal configuration of the circulation pump 27) Figure 7 is a schematic cross-sectional view of the circulation pump 27 of Figure 6 in the first embodiment. The circulation pump 27 comprises a pump housing 271, a diaphragm unit 276, a first electrode 272, a piezoelectric element 273, a second electrode 274, and a vibrating plate 275. The piezoelectric element 273 is provided between the first electrode 272 and the second electrode 274. One surface of the piezoelectric element 273 is in contact with the first electrode 272. The other surface of the piezoelectric element 273 is in contact with the second electrode 274. The first wiring 211a is connected to the first electrode 272 via an electrical connection member 277a. The first wiring 211a is a signal medium that transmits the pump control signal 605a and the pump drive signal 608a to the circulation pump 27. The second wiring 211b is connected to the second electrode 274 via an electrical connection member 277b. The second wiring 211b is a signal medium that transmits the pump control signal 605b and the pump drive signal 608b to the circulation pump 27. In this embodiment, the electrical connection members 277a and 277b are solder, but are not limited to this. Conductive materials such as gold bushings may be used for the electrical connection members 277a and 277b. Details of the pump control signals 605a and 605b and the pump drive signals 608a and 608b will be described later with reference to Figures 10 and 11. The second electrode 274 has one surface in contact with the piezoelectric element 273 and the other surface in contact with the diaphragm 275. That is, a laminate is formed by stacking the first electrode 272, the piezoelectric element 273, the second electrode 274, and the diaphragm 275 in that order. A concave pump housing 271 is provided so as to cover this laminate. Furthermore, a diaphragm unit 276 is provided on the side of the diaphragm 275 opposite to the side on which the laminate is formed. The diaphragm unit 276 comprises a diaphragm unit housing 276a, an outlet valve body 276b, and an inlet valve body 276c. The diaphragm unit housing 276a is made of a concave housing. A pressure chamber 276d is formed when the concave edge of the diaphragm unit housing 276a and the edge of the diaphragm 275 are fixed in contact. That is, the pressure chamber 276d is positioned in close contact with the diaphragm 275. An inlet and an outlet are provided at the bottom of the diaphragm unit housing 276a. The outlet valve body 276b is positioned at the outlet. The inlet valve body 276c is positioned at the inlet.The outlet valve body 276b functions as a check valve that can move freely in response to the outflow of liquid from the pressure chamber 276d. The inlet valve body 276c functions as a check valve that can move freely in response to the inflow of liquid into the pressure chamber 276d. Opposite the outlet valve body 276b, the pump outlet passage 78 shown in Figure 5 is located via the outlet. Opposite the inlet valve body 276c, the pump inlet passage 77 shown in Figure 5 is located via the inlet. Next, the flow of ink will be explained using Figure 5.

[0028] (Ink flow) Returning to Figure 5, the pump 21 in Figure 5 pressurizes and supplies ink stored in the ink tank 2 to the liquid discharge head 1. The filter 23 removes dust contained in the pressurized ink supplied from the pump 21. The ink from which dust has been removed by the filter 23 is supplied to the first valve chamber 25. As the ink supplied to the first valve chamber 25 flows into the first pressure control chamber 26, the pressure is controlled by the circulation pump 27. Next, the details of the pressure control by the circulation pump 27 will be explained using Figure 7.

[0029] By applying a voltage to the piezoelectric element 273 in Figure 7, a potential difference is generated, causing the piezoelectric element 273 to vibrate. This vibration moves the diaphragm 275, changing the volume inside the pressure chamber 276d and causing pressure fluctuations inside the pressure chamber 276d. Due to the pressure fluctuations inside the pressure chamber 276d, the outlet valve body 276b and the inlet valve body 276c move alternately, sending ink, and the circulation pump 27 functions as a piezoelectric diaphragm pump. The circulation pump 27 is driven to send ink with the pump inlet passage 77 on the downstream side and the pump outlet passage 78 on the upstream side. Now, let's return to Figure 5. Driven by the circulation pump 27 in Figure 5, the ink whose pressure is controlled inside the first pressure control chamber 26 is supplied to the supply passage 75 and the bypass passage 79. The supply passage 75 supplies ink to the flow path member 110. The flow path member 110 supplies the ink supplied from the supply passage 75 to the discharge unit 300. The ink supplied to the discharge unit 300 is supplied to the discharge element substrate 310 inside the discharge unit 300. The discharge element substrate 310 is equipped with a discharge element. The ink supplied to the discharge element substrate 310 passes through the discharge element and is then discharged into the recovery channel 76. The discharge element comprises an energy generating element, a pressure chamber, and a discharge port. The ink that passes through the pressure chamber inside the discharge element and is discharged into the recovery channel 76 is supplied to the second pressure control chamber 30. In addition, ink supplied to the second valve chamber 29 via the bypass channel 79 is supplied to the second pressure control chamber 30, which is connected to the second valve chamber 29 via a valve. Therefore, the second pressure control chamber 30 is supplied with ink from both the recovery channel 76 and the bypass channel 79. The ink supplied to the second pressure control chamber 30 is supplied to the circulation pump 27 via the pump inlet channel 77. The ink supplied to the circulation pump 27 is supplied to the first pressure control chamber 26 via the pump outlet passage 78. In this way, the ink is circulated by the circulation pump 27, passing through the ejection element formed on the ejection element substrate 310. That is, the configuration of the circulation passage can suppress the thickening of the ink near the ejection element. The circulation passage is not limited to a configuration that passes through the ejection element. For example, the circulation passage may be configured to circulate the ink inside the ejection unit 300, as long as it is within a range that effectively suppresses the thickening of the ink near the ejection element.

[0030] The ejection unit 300 is equipped with a temperature sensor (not shown) and a heating element. The CPU 400 monitors the output value of the temperature sensor provided in the ejection unit 300 and drives the heating element as appropriate. This operation makes it possible to maintain the temperature of the ejection unit 300 in a state suitable for liquid ejection. Furthermore, although this disclosure works even without a temperature sensor and heating element, when they are present, the power required for maintaining the temperature by the heating element increases as the ink circulation flow rate increases. Therefore, the effects of this disclosure can be particularly realized. Next, the first to third use cases regarding the inflow and outflow of ink will be explained using Figure 7.

[0031] (First use case) Let's describe a first use case in which ink flows into the pressure chamber 276d. Assume that a potential difference is generated from the second electrode 274 towards the first electrode 272, causing the piezoelectric element 273 and the diaphragm 275 to be displaced in a direction that expands the pressure chamber 276d. In this scenario, the inflow valve body 276c opens, and ink flows into the pressure chamber 276d from the pump inlet passage 77.

[0032] (Second use case) A second use case in which ink flows out from the pressure chamber 276d is described. Assume that a potential difference is generated from the first electrode 272 to the second electrode 274, causing the piezoelectric element 273 and the diaphragm 275 to be displaced in a direction that contracts the pressure chamber 276d. In this scenario, the outflow valve body 276b opens, and ink flows out from the pressure chamber 276d into the pump outlet passage 78.

[0033] (Third use case) A third use case will be described in which neither ink flows into nor out of the pressure chamber 276d. Assume that no potential difference is generated between the first electrode 272 and the second electrode 274. In this assumption, the piezoelectric element 273 and the diaphragm 275 are not displaced in either the expansion or contraction direction into the pressure chamber 276d. Therefore, neither ink flows into nor out of the diaphragm unit 276.

[0034] Specifically, by periodically changing the potential difference between the first electrode 272 and the second electrode 274, the circulation pump 27 allows ink to flow in through the pump inlet passage 77 and to flow out through the pump outlet passage 78. In such a circulation pump 27, variations in the manufacturing of the diaphragm 275, piezoelectric element 273, and diaphragm unit 276 can affect the fluid delivery capacity of the circulation pump 27. Specifically, the thickness of the diaphragm 275 can affect the displacement of the pressure chamber 276d. Therefore, variations in the manufacturing of the diaphragm 275 can affect the fluid delivery capacity of the circulation pump 27. In addition, the capacitance of the piezoelectric element 273 can affect the displacement speed of the piezoelectric element 273 when a constant potential difference is applied between the first electrode 272 and the second electrode 274. Therefore, variations in the manufacturing of the piezoelectric element 273 can affect the fluid delivery capacity of the circulation pump 27. Furthermore, the ease with which the outlet valve body 276b and the inlet valve body 276c of the diaphragm unit 276 can open and close may affect the ease with which liquid flows into and out of the pressure chamber 276d. Therefore, manufacturing variations in the diaphragm unit 276 may affect the liquid delivery capacity of the circulation pump 27. Next, the process of generating a drive signal to drive the circulation pump 27 based on a control signal and a reference voltage will be described.

[0035] (Pump drive circuit) Figure 8 shows a schematic example of the configuration of the pump drive circuit that drives the circulation pump 27 shown in Figure 7 in the first embodiment. The main body of the liquid discharge device 50 includes a CPU 400, a power supply 410, and a head output terminal 421. The liquid discharge head 1 includes, in addition to the ink circulation unit 54, a head input terminal 422, a boost circuit 423, an output switching circuit 424, a pump output terminal 425, and an EEPROM 427. The head output terminal 421 supplies various signals and various voltages to the head input terminal 422. Examples of various signals include the pump control signal 605 and the boost signal 606a. Examples of various voltages include the pump drive reference voltage 604. Details of the pump control signal 605, the boost signal 606a, and the pump drive reference voltage 604 will be described later. The head input terminal 422 also supplies a feedback signal to the head output terminal 421. The feedback signal will also be referred to as the FB signal below. Furthermore, among the head input terminal 422, boost circuit 423, output switching circuit 424, pump output terminal 425, and EEPROM 427, the boost circuit 423 and output switching circuit 424 function as the pump drive circuit.

[0036] A print signal 601, as image data, is input from the host device 500 to the CPU 400 included in the main body of the liquid dispensing device 50. Meanwhile, a power supply voltage 602 is supplied from the external power supply 510 to the power supply unit 410 included in the main body of the liquid dispensing device 50. Upon receiving the print signal 601 from the host device 500, the CPU 400 activates a power control signal 603 to the power supply unit 410. In this embodiment, the power control signal 603 is assumed to be high active. That is, it is assumed that the power supply unit 410 is set to operate when the power control signal 603 is high. Specifically, when the signal potential of the power control signal 603 transitions from 0V to 3.3V, the power supply unit 410 outputs a pump drive reference voltage 604 to the head output terminal 421. In this embodiment, the pump drive reference voltage 604 is assumed to be 5V. Upon receiving a print signal 601 from the host device 500, the CPU 400 outputs a pump control signal 605 and a boost signal 606a to the head output terminal 421.

[0037] (Pump control signal 605) The pump control signal 605 includes pump control signal 605a and pump control signal 605b. Pump control signal 605a and pump control signal 605b correspond to the first electrode 272 and the second electrode 274, respectively. Pump control signals 605a and 605b are sent to the output switching circuit 424 via the head output terminal 421 and the head input terminal 422. The signal potential of pump control signals 605a and 605b transitions from 0V to 3.3V, at which point each of the pump control signals 605a and 605b becomes active. That is, each of the pump control signals 605a and 605b is assumed to be highly active.

[0038] (Boost signal 606) The boost circuit 423 is driven when the signal potential of the boost signal 606 transitions from 0V to the active potential of 5V. Specifically, the head output terminal 421 supplies the pump control signal 605, the boost signal 606a, and the pump drive reference voltage 604 to the head input terminal 422. The head input terminal 422 supplies the pump drive reference voltage 604 supplied from the head output terminal 421 to the voltage input terminal of the boost circuit 423. The head input terminal 422 supplies the boost signal 606a supplied from the head output terminal 421 to the signal input terminal of the boost circuit 423. The boost circuit 423 converts the 5V pump drive reference voltage 604 to a predetermined voltage necessary for the piezoelectric element 273 provided on the circulation pump 27 to be sufficiently displaced, according to the boost signal 606a. For example, the boost circuit 423 converts the 5V pump drive reference voltage 604 to a voltage of 72V. In other words, in this embodiment, the set center voltage for the boost is assumed to be 72V. The boost circuit 423 outputs the voltage converted to 72V as the pump drive voltage 607 to the output switching circuit 424. A specific circuit example of the boost circuit 423 will be explained with reference to Figure 9.

[0039] (Boost circuit 423) Figure 9 shows an example of the circuit configuration of the boost circuit 423 in Figure 8 in the first embodiment. In the example in Figure 9, the boost circuit 423 includes a bypass capacitor 705, an inductor 701, a switching element 702, a diode 703, a capacitor 704, a voltage divider resistor 706, and a voltage divider resistor 707. For example, a chip inductor is used for the inductor 701. For example, an n-channel FET is used for the switching element 702. In Figure 9, the ground constitutes the potential that serves as the operating reference for the circuit. The ground is configured by a ground terminal, for example, as a frame ground or a signal ground. Alternatively, the ground may be configured by a ground terminal, for example, as a frame ground or a signal ground.

[0040] (Connection configuration of boost circuit 423) One terminal of the bypass capacitor 705 is connected to the ground terminal. The other terminal of the bypass capacitor 705 is connected to the voltage input terminal of the boost circuit 423. The pump drive reference voltage 604 is applied to the voltage input terminal of the boost circuit 423. One terminal of the inductor 701 is also connected to the input terminal of the boost circuit 423. The other terminal of the inductor 701 is connected to the anode of the diode 703 and the drain of the switching element 702. The source of the switching element 702 is connected to the ground terminal. When the boost signal 606a input from the signal input terminal of the boost circuit 423 is input to the gate of the switching element 702, the drain and source of the switching element 702 become conductive. One terminal of the capacitor 704 is connected to the cathode of the diode 703. The other terminal of the capacitor 704 is connected to the ground terminal. Furthermore, one terminal of the voltage divider resistor 706 and the first voltage output terminal of the boost circuit 423 are connected to the cathode of the diode 703. The first voltage output terminal of the boost circuit 423 can output the pump drive voltage 607. One terminal of the voltage divider resistor 707 is connected to the other terminal of the voltage divider resistor 706. The other terminal of the voltage divider resistor 707 is connected to the ground terminal. The connection point between the voltage divider resistor 706 and the voltage divider resistor 707 is connected to the second voltage output terminal of the boost circuit 423. The second voltage output terminal of the boost circuit 423 can output the feedback signal 606b. The feedback signal 606b is also appropriately referred to as the FB signal.

[0041] (Operation of the boost circuit 423) When the potential of the boost signal 606a transitions from ground potential to the active potential of 5V, the switching element 702 becomes conductive. Therefore, when the pump drive reference voltage 604 is applied to the voltage input terminal of the boost circuit 423, current flows from the voltage input terminal of the boost circuit 423 to the ground terminal via the inductor 701 and the switching element 702. Here, when the potential of the boost signal 606a transitions from active potential to ground potential, the switching element 702 becomes non-conductive, and a back electromotive force is generated in the inductor 701. Therefore, the current generated by the back electromotive force of the inductor 701 flows to the capacitor 704 via the diode 703. As a result, charge flows into the capacitor 704. The charge that flows into and is stored in the capacitor 704 cannot return to the anode side of the diode 703 due to the diode 703. Therefore, as the switching element 702 repeatedly switches between conductive and non-conductive states due to the boost signal 606a, charge flows into and is stored in the capacitor 704. As a result, the pump drive voltage 607 is boosted to a voltage higher than the pump drive reference voltage 604. In this embodiment, the pump drive voltage 607 is divided by the resistance ratio of the series-connected voltage divider resistor 706 and voltage divider resistor 707, and then linearly stepped down. The linearly stepped-down voltage is output as an FB signal 606b from the second voltage output terminal. The FB signal 606b is output to the CPU 400. Based on the FB signal 606b, the CPU 400 controls the on / off duty cycle of the boost signal 606a so that the potential of the pump drive voltage 607 output from the first voltage output terminal becomes 72V. Note that the boost circuit 423 is not limited to the example in Figure 9. For example, the boost circuit 423 may be composed of a charge pump circuit. Alternatively, the boost circuit 423 may be composed of a power supply unit that converts an externally input AC to 72V DC.

[0042] (Output switching circuit 424) Return to Figure 8. The output switching circuit 424 outputs the pump drive voltage 607 as a pump drive signal 608 to the pump output terminal 425 according to the pump control signal 605 input from the head input terminal 422. The pump drive signal 608 includes pump drive signal 608a and pump drive signal 608b. Details of the output switching circuit 424 will be explained using Figure 10.

[0043] Figure 10 shows an example of the circuit configuration of the output switching circuit 424 in Figure 8 in the first embodiment. The output switching circuit 424 includes a first voltage control circuit 424a and a second voltage control circuit 424b. The first voltage control circuit 424a and the second voltage control circuit 424b are provided in parallel. The first voltage control circuit 424a outputs a pump drive signal 608a based on the input of a pump control signal 605a when a pump drive voltage 607 is input to it. The first voltage control circuit 424a includes an a signal system corresponding to the first electrode 272. The a signal system controls the output of the pump drive signal 608a to the first electrode 272 via the first wiring 211a. Therefore, the a signal system can control the voltage applied to the first electrode 272. The second voltage control circuit 424b outputs a pump drive signal 608b based on the input of a pump control signal 605b when a pump drive voltage 607 is input to it. The second voltage control circuit 424b includes a b signal system corresponding to the second electrode 274. The b signal system outputs a pump drive signal 608b to the second electrode 274 via the second wiring 211b. Thus, the b signal system can control the voltage applied to the second electrode 274.

[0044] (Connection configuration of the first voltage control circuit 424a) The first voltage control circuit 424a includes a resistor 801a, transistors 802a, 803a, 805a, and capacitor 806a. Transistor 802a is an NPN transistor. Transistor 803a is a PNP transistor. Transistor 805a is an NPN transistor. One terminal of resistor 801a is connected to the collector of transistor 802a. The collector of transistor 802a is connected to the voltage input terminal of the pump drive voltage 607. The other terminal of resistor 801a is connected to the base of transistor 802a. The base of transistor 802a is connected to the base of transistor 803a, one terminal of capacitor 806a, and the collector of transistor 805a. The emitter of transistor 803a is connected to the emitter of transistor 802a. A pump drive signal 608a can be output from a signal output terminal provided between the emitter of transistor 803a and the emitter of transistor 802a. A pump control signal 605a is input to the base of transistor 805a. The emitter of transistor 805a and the other terminal of capacitor 806a are connected to the ground terminal. Note that the switching elements of the first voltage control circuit 424a are not limited to transistors 802a, 803a, and 805a. The switching elements of the first voltage control circuit 424a may be FETs.

[0045] (Operation of the first voltage control circuit 424a) (Position of pump control signal 605a: Ground potential) When the potential of the pump control signal 605a is at ground potential, the emitter and collector of transistor 805a are not conducting. Therefore, transistor 805a is open. When transistor 805a is open, the pump drive voltage 607 is applied to the bases of transistor 802a and transistor 803a. At this time, if the potential of the pump drive signal 608a is at ground potential, the potential of the emitter of transistor 802a is at ground potential. Therefore, the potential of the emitter of transistor 802a is lower than the potential of the base of transistor 802a. Consequently, base current flows from the base of transistor 802a to the output of the pump drive signal 608a. As a result, transistor 802a becomes active, and a voltage at the same potential as the pump drive voltage 607 is output as the pump drive signal 608a. In this case, the output voltage is 72V. On the other hand, the potential of the emitter of transistor 803a and the potential of the base of transistor 803a are at the same potential. Therefore, transistor 803a is open. From the above, when the potential of the pump control signal 605a is at ground potential, the potential of the pump drive signal 608a is at the potential of the pump drive voltage 607.

[0046] (Potential of pump control signal 605a: Active potential) When the potential of the pump control signal 605a is at the active potential, base current flows from the base of transistor 805a to the emitter of transistor 805a. Therefore, transistor 805a becomes active, and the bases of transistor 802a and transistor 803a are connected to the ground terminal. At this time, if the potential of the pump drive signal 608a is 72V, base current flows from the emitter of transistor 803a to the base of transistor 803a. Therefore, transistor 803a becomes active. When transistor 803a becomes active, the emitter and collector of transistor 803a become conductive, and the collector of transistor 803a is connected to the ground terminal. Therefore, the potential between the emitter of transistor 802a and the emitter of transistor 803a is at ground potential. On the other hand, since the potential of the base of transistor 802a and the potential of the emitter of transistor 802a are at the same potential, transistor 802a becomes open. Based on the above, when the potential of the pump control signal 605a is at the active potential, the potential of the pump drive signal 608a becomes the ground potential.

[0047] (Connection configuration of the second voltage control circuit 424b) The second voltage control circuit 424b includes a resistor 801b, transistors 802b, 803b, 805b, and capacitor 806b. Transistor 802b is an NPN transistor. Transistor 803b is a PNP transistor. Transistor 805b is an NPN transistor. One terminal of resistor 801b is connected to the collector of transistor 802b. The collector of transistor 802b is connected to the voltage input terminal of the pump drive voltage 607. The other terminal of resistor 801b is connected to the base of transistor 802b. The base of transistor 802b is connected to the base of transistor 803b, one terminal of capacitor 806b, and the collector of transistor 805b. The emitter of transistor 803b is connected to the emitter of transistor 802b. A pump drive signal 608b can be output from a signal output terminal located between the emitter of transistor 803b and the emitter of transistor 802b. A pump control signal 605b is input to the base of transistor 805b. The emitter of transistor 805b and the other terminal of capacitor 806b are connected to the ground terminal. Note that the switching elements of the second voltage control circuit 424b are not limited to transistors 802b, 803b, and 805b. The switching elements of the second voltage control circuit 424b may be FETs.

[0048] (Operation of the second voltage control circuit 424b) (Position of pump control signal 605b: Ground potential) When the potential of the pump control signal 605b is at ground potential, the emitter and collector of transistor 805b are not conducting. Therefore, transistor 805b is open. When transistor 805b is open, the pump drive voltage 607 is applied to the bases of transistor 802b and transistor 803b. At this time, if the potential of the pump drive signal 608b is at ground potential, the potential of the emitter of transistor 802b is at ground potential. Therefore, the potential of the emitter of transistor 802b is lower than the potential of the base of transistor 802b. Consequently, base current flows from the base of transistor 802b to the output destination of the pump drive signal 608b. As a result, transistor 802b becomes active, and the pump drive voltage 607 is output as the pump drive signal 608b. In this case, the output voltage is 72V. On the other hand, the potential of the emitter of transistor 803b and the potential of the base of transistor 803b are at the same potential. Therefore, transistor 803b is open. From the above, when the potential of the pump control signal 605b is at ground potential, the potential of the pump drive signal 608b is at the potential of the pump drive voltage 607.

[0049] (Potential of pump control signal 605b: Active potential) When the potential of the pump control signal 605b is at the active potential, base current flows from the base of transistor 805b to the emitter of transistor 805b. Therefore, transistor 805b becomes active, and the bases of transistor 802b and transistor 803b are connected to the ground terminal. At this time, if the potential of the pump drive signal 608b is 72V, base current flows from the emitter of transistor 803b to the base of transistor 803b. Therefore, transistor 803b becomes active. When transistor 803b becomes active, the emitter and collector of transistor 803b become conductive, and the collector of transistor 803b is connected to the ground terminal. Therefore, the emitter of transistor 802b and the emitter of transistor 803b are connected to the ground terminal. As a result, the potential of the pump drive signal 608b becomes the ground potential. On the other hand, since the base potential of transistor 802b and the emitter potential of transistor 802b are at the same potential, transistor 802b becomes open. Therefore, when the potential of the pump control signal 605b is at the active potential, the potential of the pump drive signal 608b becomes the ground potential.

[0050] (Pump output terminal 425) Return to Figure 8. The pump output terminal 425 is composed of pump output terminals 425a and 425b, which correspond to the first electrode 272 and the second electrode 274, respectively. The pump output terminal 425 is provided on the head board 210. Of the pump drive signals 608a and 608b, pump drive signal 608a is output to pump output terminal 425a. Of the pump drive signals 608a and 608b, pump drive signal 608b is output to pump output terminal 425b. The potential of the pump drive signals 608a and 608b transitions between 0V and 72V at the pump drive frequency. 72V is set as the pump drive voltage of the circulation pump 27. The pump drive signals 608a and 608b output from the pump output terminals 425a and 425b, respectively, are input to the pump input terminal 426 provided on the ink circulation unit 54 via the first wiring 211a and the second wiring 211b. In this embodiment, the center of the set frequency for the pump drive frequency is 20 Hz.

[0051] (Ink circulation unit 54) The ink circulation unit 54 includes a pump input terminal 426 and a circulation pump 27 as components related to the pump drive signals 608a and 608b. The pump drive signals 608a and 608b sent from the pump output terminals 425a and 425b, respectively, are input to the pump input terminal 426. The pump input terminal 426 outputs the pump drive signals 608a and 608b, respectively, to the circulation pump 27. The circulation pump 27 is driven according to the pump drive signals 608a and 608b, respectively, output from the pump input terminal 426. Next, the driving of the circulation pump 27 will be explained using Figure 11.

[0052] (Driving the circulation pump 27) Figure 11 is a timing chart of the control signals that control the pump drive circuit of Figure 8 in the first embodiment. First, the potential of the pump drive reference voltage 604 transitions from 0V to 5V. This transition applies the pump drive reference voltage 604 to the boost circuit 423. Next, the potential of the boost signal 606a transitions from 0V to 5V, repeating according to a certain rule. For example, the potential of the boost signal 606a repeats between 0V and 5V based on a constant duty cycle. This repetition increases the potential of the pump drive voltage 607 output from the boost circuit 423 from 0V to 72V. The boosted pump drive voltage 607 is applied to the output switching circuit 424. Within the output switching circuit 424, with the application of the pump drive voltage 607, the potentials of the pump drive signals 608a and 608b rise to 72V, becoming the same potential as the pump drive voltage 607.

[0053] (Drive pulse width T11) Next, the potential of the pump control signal 605a transitions from 0V to 3.3V. When the potential of the pump control signal 605a is 3.3V, the potential of the pump control signal 605b is 0V. After the potential of the pump control signal 605a transitions to 3.3V, the potential of the pump control signal 605a is maintained at 3.3V over the drive pulse width T11. Meanwhile, as the potential of the pump control signal 605a transitions to 3.3V, the potential of the pump drive signal 608a decreases from 72V to 0V. The time it takes to decrease from 72V to 0V mainly depends on the capability of the boost circuit 423 and the capacitance of the piezoelectric element 273. The higher the capability of the boost circuit 423, the longer the time it takes to decrease from 72V to 0V. While the potential of the pump drive signal 608a is decreasing, the potential of the pump control signal 605b remains at 0V, so the potential of the pump drive signal 608b remains at 72V. The potential of the pump drive signal 608a reaches 0V and remains at 0V for the duration of the drive pulse width T11 during which the pump control signal 605a maintains a voltage of 3.3V. Therefore, during the drive pulse width T11, there is a period when the potential difference between the potential of the pump drive signal 608a and the potential of the pump drive signal 608b is 72V. During this period, the potential difference between the second electrode 274 and the first electrode 272 is 72V. This potential difference causes the volume of the piezoelectric element 273 to displace, and ink flows from the pump inlet channel 77 into the pressure chamber 276d.

[0054] (Drive pulse width T12) Next, as the potential of the pump control signal 605a transitions to 0V, the potential of the pump control signal 605b transitions from 0V to 3.3V. After the potential of the pump control signal 605b transitions to 3.3V, the potential of the pump control signal 605b is maintained at 3.3V for the duration of the drive pulse width T12. Meanwhile, as the potential of the pump control signal 605b transitions to 3.3V, the potential of the pump drive signal 608b decreases from 72V to 0V. After the potential of the pump drive signal 608b reaches 0V, it remains at 0V for the duration of the drive pulse width T12 during which the pump control signal 605b continues to maintain 3.3V. While the potential of the pump drive signal 608b is decreasing, the potential of the pump control signal 605a remains at 0V, so the potential of the pump drive signal 608a transitions from 0V to 72V. After the potential of the pump drive signal 608a reaches 72V, the potential of the pump drive signal 608a remains at 72V while the potential of the pump control signal 605a remains at 0V. Therefore, at a drive pulse width T12, the potential difference between the potential of the pump drive signal 608a and the potential of the pump drive signal 608b becomes -72V. Due to this potential difference, the volume of the piezoelectric element 273 is displaced, and ink flows out from the pressure chamber 276d to the pump outlet channel 78.

[0055] (Summary of timing charts) After the period T12 described above has elapsed, the pump control signal 605a transitions again to the active potential of 3.3V over the drive pulse width T11. That is, control is repeatedly performed in T11+T12, where the drive pulse width T11 and the drive pulse width T12 constitute one period. In this embodiment, the center setting value of this T11+T12 is set to 50ms. The drive frequency is set to 20Hz.

[0056] Returning to Figure 8, as shown in Figure 8, the ink circulation unit 54 is equipped with an EEPROM (Electrically Erasable Programmable ReadOnly Memory) 427. The EEPROM 427 contains information 609 regarding the capacitance of the piezoelectric element 273 of the circulation pump 27.

[0057] The timing at which the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 is written to the EEPROM 427 is not particularly limited. For example, the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 may be written during the assembly process of the liquid ejection head 1. Alternatively, the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 may be written during the inspection process before the liquid ejection head 1 is incorporated into the liquid ejection device 50. Alternatively, the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 may be written during the process of incorporating the liquid ejection head 1 into the liquid ejection device 50. Alternatively, the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 may be written before the EEPROM 427 is mounted on the ink circulation unit 54. The capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 may also be obtained by integrating the discharge current value obtained by discharging the piezoelectric element 273 of the circulation pump 27 through a resistor after it has been fully charged. That is, the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 may be measured by the constant current discharge method. Alternatively, the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 may be measured by an LCR meter. The CPU 400 reads the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 from the EEPROM 427 via the head input terminal 422. The capacitance information 609 of the piezoelectric element 273 of the circulation pump 27 is used as information regarding the fluid delivery capacity of the circulation pump 27, so-called capacity information of the circulation pump 27. The capacity information of the circulation pump 27 is information that can be set by the components of the circulation pump 27, as will be described in detail later. Furthermore, the capacity information of the circulation pump 27 is an indicator of the ability to circulate liquid. In this embodiment, an example of using the EEPROM 427 as a configuration for storing information regarding the fluid delivery capacity of the circulation pump 27 is described, but it is not limited to this. For example, the configuration for storing information regarding the fluid delivery capacity of the circulation pump 27 may be an EPROM (Erasable Programmable ReadOnly Memory). Alternatively, the configuration for storing information regarding the fluid delivery capacity of the circulation pump 27 may be a mask ROM (ReadOnly Memory).

[0058] (Information on the capabilities of the circulation pump 27: capacitance; pump drive frequency) Figure 12 is a table showing the correspondence between the capacitance of the piezoelectric element 273 provided in the circulation pump 27 in the first embodiment and the pump drive frequency. The capacitance of the piezoelectric element 273 is a component of the circulation pump 27 and can be used as performance information for the circulation pump 27. Therefore, the drive of the circulation pump 27 can be controlled based on the capacitance of the piezoelectric element 273. Furthermore, in this embodiment, it is assumed that not only the capacitance information 609 of the piezoelectric element 273 of the circulation pump 27, but also the contents of the table shown in Figure 12 are written to the EEPROM 427.

[0059] Specifically, the CPU 400 reads the corresponding pump drive frequency as the pump control signal 605 by referring to the table in Figure 12, based on the capacitance information 609 of the piezoelectric element 273 read from the EEPROM 427. The timing chart in Figure 11 corresponds to the case where the capacitance information 609 of the piezoelectric element 273 is 20 nF. More specifically, as the capacitance value of the piezoelectric element 273 increases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied decreases. Therefore, as the capacitance value of the piezoelectric element 273 increases, it is preferable to set the pump drive frequency higher than the set center. On the other hand, as the capacitance value of the piezoelectric element 273 decreases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied increases. Therefore, as the capacitance value of the piezoelectric element 273 decreases, it is preferable to set the pump drive frequency lower than the set center. In other words, when the capacitance of the piezoelectric element 273 is a second capacitance which is greater than the first capacitance, the CPU 400 preferably increases the driving frequency of the circulation pump 27 compared to the case of the first capacitance. By performing such processing, even if there are manufacturing variations in the capacitance of the piezoelectric element 273 of the circulation pump 27, it is possible to suppress variations in the liquid delivery capacity of the circulation pump 27. That is, the circulation pump 27 can be driven at the circulation flow rate required by the liquid discharge device 50.

[0060] (Second embodiment) (Information on the capabilities of the circulation pump 27: Thickness of the diaphragm 275; Pump drive frequency) The second embodiment differs from the first embodiment in that it utilizes the thickness of the diaphragm 275 as performance information for the circulation pump 27. The differences from the first embodiment will be explained below. Figure 13 is a table showing the correspondence between the thickness of the diaphragm 275 provided in the circulation pump 27 in the second embodiment and the pump drive frequency. The diaphragm thickness in Figure 13 refers to the thickness of the diaphragm 275. The diaphragm 275 is a component of the circulation pump 27. The thickness of the diaphragm 275 can be performance information for the circulation pump 27. Therefore, the drive of the circulation pump 27 can be controlled based on the thickness of the diaphragm 275. In this embodiment, it is assumed that the information 629 regarding the thickness of the diaphragm 275 and the contents of the table shown in Figure 13 are written to the EEPROM 427.

[0061] The timing at which the information 629 regarding the thickness of the diaphragm 275 is written to the EEPROM 427 is not particularly limited. For example, the information 629 regarding the thickness of the diaphragm 275 may be written during the assembly process of the liquid ejection head 1. Alternatively, the information 629 regarding the thickness of the diaphragm 275 may be written during the inspection process before the liquid ejection head 1 is incorporated into the liquid ejection device 50. Alternatively, the information 629 regarding the thickness of the diaphragm 275 may be written during the process of incorporating the liquid ejection head 1 into the liquid ejection device 50. Alternatively, the information 629 regarding the thickness of the diaphragm 275 may be written before the EEPROM 427 is mounted on the ink circulation unit 54. The information 629 regarding the thickness of the diaphragm 275 may be measured, for example, with a laser distance meter during the assembly process.

[0062] Specifically, the CPU 400 reads the corresponding pump drive frequency as the pump control signal 625 by referring to the table in Figure 13, based on the information 629 of the diaphragm thickness 275 read from the EEPROM 427. More specifically, as the value of the diaphragm thickness 275 increases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied decreases. Therefore, as the value of the diaphragm thickness 275 increases, it is preferable to set the pump drive frequency higher than the set center. On the other hand, as the value of the diaphragm thickness 275 decreases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied increases. Therefore, as the value of the diaphragm thickness 275 decreases, it is preferable to set the pump drive frequency lower than the set center. In other words, when the thickness of the diaphragm thickness 275 is a second diaphragm thickness which is thicker than the first diaphragm thickness, the CPU 400 prefers to increase the drive frequency of the circulation pump 27 compared to the case of the first diaphragm thickness. By performing this process, even if there are manufacturing variations in the thickness of the diaphragm 275, variations in the liquid delivery capacity of the circulation pump 27 can be suppressed. In other words, the circulation pump 27 can be driven at the circulation flow rate required by the liquid discharge device 50.

[0063] (Third embodiment) (Information on the capabilities of circulation pump 27: Diaphragm valve thickness; Pump drive frequency) The third embodiment differs from the first and second embodiments in that it utilizes the diaphragm valve thickness, specifically the outlet valve body 276b and the inlet valve body 276c of the diaphragm unit 276, as performance information for the circulation pump 27. The differences from the first and second embodiments will be explained below. Figure 14 is a table showing the correspondence between the thickness of the valve body of the diaphragm unit provided in the circulation pump in the third embodiment and the pump drive frequency. The diaphragm valve thickness in Figure 14 refers to the thickness of the outlet valve body 276b and the inlet valve body 276c, respectively. The outlet valve body 276b and the inlet valve body 276c are components of the circulation pump 27. The thickness of the outlet valve body 276b and the inlet valve body 276c can serve as performance information for the circulation pump 27. Therefore, the drive of the circulation pump 27 can be controlled based on the thickness of the outlet valve body 276b and the inlet valve body 276c, respectively. Furthermore, in this embodiment, it is assumed that the information 639 regarding the thickness of the outflow valve body 276b and the inflow valve body 276c, and the contents of the table shown in Figure 14, are written to the EEPROM 427.

[0064] The timing at which the information 639 regarding the thicknesses of the outlet valve body 276b and the inlet valve body 276c is written to the EEPROM 427 is not particularly limited. For example, the information 639 regarding the thicknesses of the outlet valve body 276b and the inlet valve body 276c may be written during the assembly process of the liquid ejection head 1. Alternatively, the information 639 regarding the thicknesses of the outlet valve body 276b and the inlet valve body 276c may be written during the inspection process before the liquid ejection head 1 is installed in the liquid ejection device 50. Alternatively, the information 639 regarding the thicknesses of the outlet valve body 276b and the inlet valve body 276c may be written during the process of installing the liquid ejection head 1 in the liquid ejection device 50. Alternatively, the information 639 regarding the thicknesses of the outlet valve body 276b and the inlet valve body 276c may be written before the EEPROM 427 is mounted on the ink circulation unit 54. The information 639 regarding the thickness of the outlet valve body 276b and the inlet valve body 276c may be measured, for example, with a laser distance meter during the assembly process.

[0065] Specifically, the CPU 400 reads the corresponding pump drive frequency as a pump control signal 635 by referring to the table in Figure 14, based on the information 639 regarding the thickness of the outlet valve body 276b and the inlet valve body 276c, respectively, read from the EEPROM 427. More specifically, as the thickness values ​​of the outlet valve body 276b and the inlet valve body 276c increase, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied decreases. Therefore, as the thickness values ​​of the outlet valve body 276b and the inlet valve body 276c increase, it is preferable to set the pump drive frequency higher than the set center. On the other hand, as the thickness values ​​of the outlet valve body 276b and the inlet valve body 276c decrease, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied increases. Therefore, as the thickness values ​​of the outlet valve body 276b and the inlet valve body 276c decrease, it is preferable to set the pump drive frequency lower than the set center. In other words, the CPU 400 may increase the drive frequency of the circulation pump 27 when the thickness of the inlet valve body 276c is a second valve thickness which is thicker than the first valve thickness. Also, the CPU 400 may increase the drive frequency of the circulation pump 27 when the thickness of the outlet valve body 276b is a second valve thickness which is thicker than the first valve thickness. By performing such processing, even if there are manufacturing variations in the thickness of the outlet valve body 276b and the inlet valve body 276c, it is possible to suppress variations in the liquid delivery capacity of the circulation pump 27. That is, the circulation pump 27 can be driven at the circulation flow rate required by the liquid discharge device 50. Figure 14 shows an example in which the average values ​​of the outlet valve body 276b and the inlet valve body 276c are stored in the EEPROM 427, but it is not limited to this. The outlet valve body 276b and the inlet valve body 276c may each be stored in separate tables. In addition, information indicating the height of the pressure chamber 276d, or information indicating the opening areas of the inlet and outlet, may be stored in the EEPROM 427, not limited to the outlet valve body 276b and the inlet valve body 276c.

[0066] (Fourth embodiment) (Information on the capabilities of the circulation pump 27: Rank of the components of the circulation pump 27; Pump drive frequency) The fourth embodiment differs from the first to third embodiments in that it utilizes the rank of the components of the circulation pump 27 as performance information for the circulation pump 27. The differences from the first to third embodiments will be explained below. Figure 15 is a table showing the ranks corresponding to the capacitance of the piezoelectric element, the thickness of the diaphragm, and the diaphragm valve thickness of the valve body, which are provided in the circulation pump in the fourth embodiment. Figure 16 is a table showing the correspondence between the sum of the ranks and the pump drive frequency in the fourth embodiment. As shown in Figure 15, ranks from +4 to -4 are assigned to the capacitance of the piezoelectric element 273, the thickness of the diaphragm 275, and the average values ​​of the outlet side valve body 276b and the inlet side valve body 276c. In this embodiment, it is assumed that the sum of the ranks of the capacitance of the piezoelectric element 273, the thickness of the diaphragm 275, and the average values ​​of the outlet side valve body 276b and the inlet side valve body 276c, and the contents of the table shown in Figure 16 are written to the EEPROM 427.

[0067] Specifically, the CPU 400 reads the corresponding pump drive frequency as the pump control signal 645 by referring to the table in Figure 16, based on the sum of ranks 649 read from the EEPROM 427. More specifically, as the sum of ranks increases on the positive side, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied increases. Therefore, as the sum of ranks increases on the positive side, the fluid delivery capacity of the circulation pump 27 is higher, so it is preferable to set the pump drive frequency lower than the set center. On the other hand, as the sum of ranks increases on the negative side, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied decreases. Therefore, as the sum of ranks increases on the negative side, the fluid delivery capacity of the circulation pump 27 is lower, so it is preferable to set the pump drive frequency higher than the set center. By performing this processing, even if there are manufacturing variations in the components of the circulation pump 27, it is possible to suppress variations in the fluid delivery capacity of the circulation pump 27. That is, the circulation pump 27 can be driven at the circulation flow rate required by the liquid discharge device 50. Furthermore, the total rank value of 649 may be weighted accordingly. For example, the capacitance of the piezoelectric element 273 may be weighted.

[0068] (Fifth embodiment) (Information on the capabilities of circulation pump 27: capacitance; pump drive voltage) The fifth embodiment is similar to the first embodiment in that it utilizes the capacitance of the piezoelectric element 273 as the capacity information of the circulation pump 27, but differs from the first to fourth embodiments in that it controls the pump drive voltage. The differences from the first to fourth embodiments will be mainly explained below. Figure 17 is a table showing the correspondence between the capacitance of the piezoelectric element provided in the circulation pump 27 and the pump drive voltage in the fifth embodiment. In this embodiment, it is assumed that not only the capacitance information 659 of the piezoelectric element 273 of the circulation pump 27, but also the contents of the table shown in Figure 17 are written to the EEPROM 427.

[0069] Specifically, the CPU 400, based on the capacitance information 659 of the piezoelectric element 273 read from the EEPROM 427, refers to the table in Figure 17 and outputs a boost signal 656a to set the corresponding pump drive voltage. More specifically, as the capacitance value of the piezoelectric element 273 increases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied decreases. Therefore, as the capacitance value of the piezoelectric element 273 increases, it is preferable to output a boost signal 656a so that the pump drive voltage is set higher than the set center. On the other hand, as the capacitance value of the piezoelectric element 273 decreases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied increases. Therefore, as the capacitance value of the piezoelectric element 273 decreases, it is preferable to output a boost signal 656a so that the pump drive voltage is set lower than the set center. By performing this process, even if there are manufacturing variations in the capacitance of the piezoelectric element 273 of the circulation pump 27, variations in the liquid delivery capacity of the circulation pump 27 can be suppressed. In other words, the circulation pump 27 can be driven at the circulation flow rate required by the liquid discharge device 50.

[0070] (Sixth embodiment) (Information on the capabilities of circulation pump 27: capacitance; pump drive pulse width) The sixth embodiment is similar to the first embodiment in that it utilizes the capacitance of the piezoelectric element 273 as the capability information of the circulation pump 27, but differs from the first to fifth embodiments in that it controls the pump drive pulse width. The differences from the first to fifth embodiments will be mainly explained below. Figure 18 is a timing chart of the control signals that control the pump drive circuit in the sixth embodiment. The pump drive reference voltage 664 transitions from 0V to 5V. Thereafter, the potential of the boost signal 666a transitions between 0V and 5V according to a prescribed rule. Due to the transition of the potential of the boost signal 666a, the pump drive voltage 667 is boosted from 0V to 72V. Thereafter, the potential of the pump control signal 665a transitions from 0V to 3.3V. The potential of the pump control signal 665b remains at 0V. The potential of the pump control signal 665a remains at 3.3V over a predetermined drive pulse width T23. The potential of the pump drive signal 668a transitions from 72V to 0V. When the potential of the pump control signal 665a is 3.3V and the potential of the pump drive signal 668a transitions from 72V to 0V, the potential of the pump control signal 665b is 0V. Therefore, the potential of the pump drive signal 668b is 72V. With a drive pulse width T23, the potential difference between the potential of the pump drive signal 668b and the potential of the pump drive signal 668a, that is, the potential difference between the potential of the second electrode 274 of the circulation pump 27 and the potential of the first electrode 272, is 72V. Next, the potential of the pump control signal 665a transitions to 0V. After a predetermined period T21 has elapsed since the potential of the pump control signal 665a transitioned from 0V to 3.3V, the potential of the pump control signal 665b transitions from 0V to 3.3V, and the potential of the pump control signal 665b is maintained at 3.3V over a predetermined drive pulse width T24. At a drive pulse width T24, the potential of the pump drive signal 668a becomes 72V, and the potential of the pump drive signal 668V becomes 0V. Therefore, the potential difference between the potential of the second electrode 274 and the potential of the first electrode 272 becomes -72V. After a predetermined period T22 has elapsed since the potential of the pump control signal 665b transitioned from 0V to 3.3V, the potential of the pump control signal 665a transitioned again from 0V to 3.3V over a predetermined period T21. That is, control with periods T21 and T22 as one cycle is repeatedly performed. In this embodiment, the center setting value of the drive pulse width T11 + T12 is assumed to be 50ms, and the drive frequency is assumed to be 20Hz.Furthermore, the center setting value for drive pulse widths T23 and T24 is assumed to be 12.5 ms.

[0071] Figure 19 is a table showing the correspondence between the capacitance of a piezoelectric element provided in the circulation pump and the pump drive pulse width in the sixth embodiment. In this embodiment, it is assumed that not only the capacitance information 669 of the piezoelectric element 273 of the circulation pump 27, but also the contents of the table shown in Figure 19 are written to the EEPROM 427.

[0072] Specifically, the CPU 400, based on the capacitance information 669 of the piezoelectric element 273 read from the EEPROM 427, refers to the table in Figure 19 and outputs a boost signal 666a to set the corresponding pump drive pulse width. More specifically, as the capacitance value of the piezoelectric element 273 increases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied decreases. Therefore, as the capacitance value of the piezoelectric element 273 increases, it is preferable to output a boost signal 666a so that the pump drive pulse width is set to a width larger than the set center. On the other hand, as the capacitance value of the piezoelectric element 273 decreases, the displacement speed of the piezoelectric element 273 when the pump drive voltage 607 is applied increases. Therefore, as the capacitance value of the piezoelectric element 273 decreases, it is preferable to output a boost signal 666a so that the pump drive pulse width is set to a width smaller than the set center. By performing this process, even if there are manufacturing variations in the capacitance of the piezoelectric element 273 of the circulation pump 27, variations in the liquid delivery capacity of the circulation pump 27 can be suppressed. In other words, the circulation pump 27 can be driven at the circulation flow rate required by the liquid discharge device 50.

[0073] (Seventh Embodiment) The seventh embodiment differs from the first to sixth embodiments in the placement of the EEPROM 467. The differences from the first to sixth embodiments will be mainly described below. Figure 20 is a schematic example of the configuration of the pump drive circuit that drives the circulation pump 27 in the seventh embodiment. The EEPROM 467 is located outside the ink circulation unit 54 and inside the liquid ejection head 1. The EEPROM 467 has capacitance information 669 of the piezoelectric element 273 written to it. The CPU 400 reads the capacitance information 669 of the piezoelectric element 273 from the EEPROM 467 via the head input terminal 472. As in this embodiment, the EEPROM 467, which stores capability information that can be set by the components of the circulation pump 27, such as capacitance information 669 of the piezoelectric element 273, may be located outside the ink circulation unit 54 and inside the liquid ejection head 1. Specifically, the EEPROM 467 may be mounted on the head board 210. By arranging it in this way, the head board 210 can be shared. Therefore, it is possible to miniaturize the liquid ejection head 1.

[0074] (Eighth embodiment) The eighth embodiment differs from the first to seventh embodiments in that the EEPROM 467 is located on the main body side of the liquid dispensing device 50. The differences from the first to seventh embodiments will be mainly described below. Figure 21 is a diagram showing a schematic example of the configuration of a pump drive circuit that drives the circulation pump 27 in the eighth embodiment. The EEPROM 467 is located outside the liquid dispensing head 1 and on the main body side of the liquid dispensing device 50. The capacitance information 669 of the piezoelectric element 273 is written to the EEPROM 467. The CPU 400 reads the capacitance information 669 of the piezoelectric element 273 from the EEPROM 467. As in this embodiment, the EEPROM 467, which stores capability information that can be set by the components of the circulation pump 27, such as the capacitance information 669 of the piezoelectric element 273, may be located outside the liquid dispensing head 1 and on the main body side of the liquid dispensing device 50. In this configuration, where the circulation pump 27 is provided separately from the liquid discharge head 1, after the process of incorporating the circulation pump 27 into the liquid discharge device 50, the capacity information that can be set by the components of the circulation pump 27 can be written to the EEPROM 467. Therefore, manufacturing management of the liquid discharge device 50 becomes easier.

[0075] (Other embodiments) Although various examples and embodiments of this disclosure have been described above, the spirit and scope of this disclosure are not limited to the specific descriptions herein. This disclosure is not limited to the embodiments described above, and various modifications may be made. Furthermore, this disclosure may combine some of the embodiments described above as appropriate.

[0076] (Variation 1) For example, an example of controlling the pump drive frequency or pump drive voltage 607 of the circulation pump 27 based on the capacity information of the circulation pump 27 has been described, but the explanation is not limited to this. For example, the pump drive frequency of the circulation pump 27 may vary due to manufacturing variations in the drive circuit 40A in Figure 2. In this case, the drive of the circulation pump 27 may be controlled by the pump drive voltage 607 of the circulation pump 27. Alternatively, the pump drive voltage 607 of the circulation pump 27 may vary due to manufacturing variations in the drive circuit 40A in Figure 2. In this case, the drive of the circulation pump 27 may be controlled by the pump drive frequency of the circulation pump 27.

[0077] The disclosure of this embodiment includes the following configurations, which are representative of the liquid dispensing device and liquid dispensing head.

[0078] <Configuration 1> A circulation channel that allows liquid to circulate, A discharge unit that discharges the liquid circulating in the aforementioned circulation channel, A circulation pump that circulates the liquid in the aforementioned circulation channel, A pump driving means for driving the circulation pump, based on the capability information that can be set by the components of the circulation pump, A head board on which the function of the pump drive means is implemented, A storage means mounted on the head board for storing the capability information, Equipped with, The liquid discharge head is characterized in that the aforementioned capacity information is an indicator of the capacity to circulate liquid in the circulation channel.

[0079] <Configuration 2> The circulation pump is equipped with a piezoelectric element that vibrates when a voltage is applied, and uses the vibration of the piezoelectric element to generate a circulating flow of liquid in the circulation channel. The liquid discharge head according to configuration 1, characterized in that the pump driving means utilizes the capacitance of the piezoelectric element as the capacity information.

[0080] <Structure 3> The liquid discharge head according to configuration 2, characterized in that the pump driving means controls the driving frequency of the circulation pump based on the capacitance of the piezoelectric element.

[0081] <Structure 4> The liquid discharge head according to configuration 3, characterized in that when the capacitance of the piezoelectric element is a second capacitance which is larger than the first capacitance, the driving frequency of the circulation pump is increased compared to the case of the first capacitance.

[0082] <Composition 5> The circulation pump further comprises a vibrating plate that vibrates based on the application of voltage, and moves the vibrating plate to generate a circulating flow of the liquid. The liquid discharge head according to configuration 1, characterized in that the pump driving means utilizes the thickness of the diaphragm as the capacity information.

[0083] <Composition 6> The liquid discharge head according to configuration 5, characterized in that the pump driving means controls the driving frequency of the circulation pump based on the thickness of the diaphragm.

[0084] <Composition 7> The liquid discharge head according to configuration 6, characterized in that when the thickness of the diaphragm is a second diaphragm thickness which is greater than the thickness of the first diaphragm thickness, the pump driving means increases the driving frequency of the circulation pump compared to the case of the first diaphragm thickness.

[0085] <Structure 8> The circulation pump further comprises a diaphragm unit that controls the inflow and outflow of the liquid circulating in the circulation channel, The diaphragm unit is A pressure chamber for generating pressure fluctuations to create a circulating flow of the liquid circulating in the aforementioned circulation channel, An inlet valve body that controls the inflow of the liquid circulating in the circulation channel from the circulation channel to the pressure chamber, An outlet valve body that controls the outflow of liquid circulating in the circulation channel from the pressure chamber to the circulation channel, Equipped with, The liquid discharge head according to configuration 1, characterized in that the pump driving means utilizes the respective thicknesses of the inlet valve body and the outlet valve body as the capacity information.

[0086] <Composition 9> The liquid discharge head according to configuration 8, characterized in that when the thickness of the front inlet valve body is a second valve thickness which is greater than the first valve thickness, the driving frequency of the circulation pump is increased compared to the case of the first valve thickness.

[0087] <Composition 10> The liquid discharge head according to configuration 8, characterized in that when the thickness of the front outlet side valve body is a second valve thickness which is greater than the first valve thickness, the driving frequency of the circulation pump is increased compared to the case of the first valve thickness.

[0088] <Composition 11> The aforementioned circulation pump, The piezoelectric chip A diaphragm is placed on top of the piezoelectric element, A diaphragm unit that controls the inflow and outflow of the liquid circulating in the circulation channel, Equipped with, The diaphragm unit is A pressure chamber is positioned in close contact with the diaphragm, An inlet valve body that controls the inflow of the liquid circulating in the circulation channel from the circulation channel to the pressure chamber, An outlet valve body that controls the outflow of liquid circulating in the circulation channel from the pressure chamber to the circulation channel, Equipped with, The liquid discharge head according to configuration 2, characterized in that the pump driving means utilizes a combination of the capacitance of the piezoelectric element, the thickness of the diaphragm, and the respective thicknesses of the inlet valve body and the outlet valve body as the capability information.

[0089] <Composition 12> The liquid discharge head according to configuration 2, characterized in that the pump driving means controls the driving voltage of the circulation pump based on the capacitance of the piezoelectric element.

[0090] <Composition 13> The liquid discharge head according to configuration 2, characterized in that the pump driving means controls the drive pulse width of the circulation pump based on the capacitance of the piezoelectric element.

[0091] <Composition 14> A storage means mounted on the head board for storing the capability information, A liquid dispensing head according to configuration 1, further comprising the above.

[0092] <Composition 15> The system further comprises a storage means for storing the aforementioned capability information, The liquid dispensing head according to configuration 1, characterized in that the storage stage is mounted on the main body side of the liquid dispensing device in which the liquid dispensing head is housed.

[0093] <Composition 16> A circulation channel that allows liquid to circulate, A discharge unit that discharges the liquid circulating in the aforementioned circulation channel, A circulation pump that circulates the liquid in the aforementioned circulation channel, A pump driving means for driving the circulation pump, based on the capability information that can be set by the components of the circulation pump, Equipped with, The liquid dispensing device is characterized in that the capacity information is an indicator of the capacity to circulate the liquid in the circulation channel. [Explanation of symbols]

[0094] 1. Liquid dispensing head 27 Circulation pump 400 CPU

Claims

1. A circulation channel that allows liquid to circulate, A discharge unit that discharges the liquid circulating in the aforementioned circulation channel, A circulation pump that circulates the liquid in the aforementioned circulation channel, A pump driving means for driving the circulation pump, based on the capability information that can be set by the components of the circulation pump, A head board on which the function of the pump drive means is implemented, A storage means mounted on the head board for storing the capability information, Equipped with, The liquid discharge head is characterized in that the aforementioned capacity information is an indicator of the capacity to circulate liquid in the circulation channel.

2. The circulation pump is equipped with a piezoelectric element that vibrates when a voltage is applied, and uses the vibration of the piezoelectric element to generate a circulating flow of liquid in the circulation channel. The liquid discharge head according to claim 1, characterized in that the pump driving means utilizes the capacitance of the piezoelectric element as the capacity information.

3. The liquid discharge head according to claim 2, characterized in that the pump driving means controls the driving frequency of the circulation pump based on the capacitance of the piezoelectric element.

4. The liquid discharge head according to claim 3, characterized in that when the capacitance of the piezoelectric element is a second capacitance which is larger than the first capacitance, the driving frequency of the circulation pump is increased compared to the case of the first capacitance.

5. The circulation pump further comprises a vibrating plate that vibrates based on the application of voltage, and moves the vibrating plate to generate a circulating flow of the liquid. The liquid discharge head according to claim 1, characterized in that the pump driving means utilizes the thickness of the diaphragm as the capacity information.

6. The liquid discharge head according to claim 5, characterized in that the pump driving means controls the driving frequency of the circulation pump based on the thickness of the diaphragm.

7. The liquid discharge head according to claim 6, characterized in that when the thickness of the diaphragm is a second diaphragm thickness which is greater than the thickness of the first diaphragm, the driving frequency of the circulation pump is increased compared to the case of the first diaphragm thickness.

8. The circulation pump further comprises a diaphragm unit that controls the inflow and outflow of the liquid circulating in the circulation channel, The diaphragm unit is A pressure chamber for generating pressure fluctuations to create a circulating flow of the liquid circulating in the aforementioned circulation channel, An inlet valve body that controls the inflow of the liquid circulating in the circulation channel from the circulation channel to the pressure chamber, An outlet valve body that controls the outflow of liquid circulating in the circulation channel from the pressure chamber to the circulation channel, Equipped with, The liquid discharge head according to claim 1, characterized in that the pump driving means utilizes the respective thicknesses of the inlet valve body and the outlet valve body as the capacity information.

9. The liquid discharge head according to claim 8, characterized in that when the thickness of the front inlet valve body is a second valve thickness which is greater than the first valve thickness, the driving frequency of the circulation pump is increased compared to the case of the first valve thickness.

10. The liquid discharge head according to claim 8, characterized in that when the thickness of the front outlet side valve body is a second valve thickness which is greater than the first valve thickness, the driving frequency of the circulation pump is increased compared to the case of the first valve thickness.

11. The aforementioned circulation pump, The piezoelectric chip A diaphragm is placed on top of the piezoelectric element, A diaphragm unit that controls the inflow and outflow of the liquid circulating in the circulation channel, Equipped with, The diaphragm unit is A pressure chamber is positioned in close contact with the diaphragm, An inlet valve body that controls the inflow of the liquid circulating in the circulation channel from the circulation channel to the pressure chamber, An outlet valve body that controls the outflow of liquid circulating in the circulation channel from the pressure chamber to the circulation channel, Equipped with, The liquid discharge head according to claim 2, characterized in that the pump driving means utilizes a combination of the capacitance of the piezoelectric element, the thickness of the diaphragm, and the respective thicknesses of the inlet valve body and the outlet valve body as the capability information.

12. The liquid discharge head according to claim 2, characterized in that the pump driving means controls the driving voltage of the circulation pump based on the capacitance of the piezoelectric element.

13. The liquid discharge head according to claim 2, characterized in that the pump driving means controls the drive pulse width of the circulation pump based on the capacitance of the piezoelectric element.

14. A storage means mounted on the head board for storing the capability information, The liquid dispensing head according to claim 1, further comprising the features described above.

15. The system further comprises a storage means for storing the aforementioned capability information, The liquid dispensing head according to claim 1, characterized in that the storage means is mounted on the main body side of the liquid dispensing device in which the liquid dispensing head is housed.

16. A circulation channel that allows liquid to circulate, A discharge unit that discharges the liquid circulating in the aforementioned circulation channel, A circulation pump that circulates the liquid in the aforementioned circulation channel, A pump driving means for driving the circulation pump, based on the capability information that can be set by the components of the circulation pump, Equipped with, The liquid dispensing device is characterized in that the capacity information is an indicator of the capacity to circulate the liquid in the circulation channel.

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