LIQUID EJECTION HEAD AND LIQUID EJECTION APPARATUS

Abstract

To solve the problem that particles contained in liquid may clog a flow path.SOLUTION: A liquid discharge device 1, which is a liquid discharge head 20 that discharges liquid from a nozzle N, comprises: a plurality of individual flow paths 71 including pressure chambers 77A communicating with the nozzle; a common supply flow path 74A communicating with the plurality of individual flow paths in common, which supplies liquid to the plurality of individual flow paths; and an adjustment part 91, provided between the pressure chambers and the common supply flow paths, which varies cross sectional areas of the flow paths through which liquid flows. The adjustment part, when pressure of liquid in the common supply flow path is higher than pressure of liquid in the pressure chambers and when a pressure difference that is a difference between the pressure of liquid in the common supply flow path and the pressure of liquid in the pressure chambers is equal to a first pressure difference, varies the cross sectional areas to first cross sectional areas, and when the pressure difference is equal to a second pressure difference larger than the first pressure difference, varies the cross sectional areas to second cross sectional areas larger than the first cross sectional areas.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus. [Background technology]

[0002] There is a liquid ejection head that ejects liquid such as ink. The liquid ejection head described in Patent Document 1 includes a plurality of nozzles that eject liquid, a plurality of individual flow paths provided for each of the plurality of nozzles, and a liquid supply chamber that is commonly connected to the plurality of individual flow paths. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-24082 Summary of the Invention [Problem to be solved by the invention]

[0004] In a liquid ejection head, a plurality of individual flow paths are connected to a common liquid chamber. The cross-sectional area of ​​the individual flow paths is narrower than the cross-sectional area of ​​the liquid supply chamber. Therefore, in the region where the cross-sectional area of ​​the flow path is narrower, particles present in the liquid may accumulate and cause the flow path to become clogged. [Means for solving the problem]

[0005] A liquid ejection head according to one aspect of the present invention is a liquid ejection head that ejects liquid from a nozzle, the liquid ejection head including a plurality of individual flow paths including a pressure chamber communicating with the nozzle, a common supply flow path that communicates in common with the plurality of individual flow paths and supplies liquid to the plurality of individual flow paths, and an adjustment unit that is provided between the pressure chamber and the common supply flow path and changes a cross-sectional area of ​​the flow path through which the liquid flows. When the pressure of the liquid in the common supply flow path is higher than the pressure of the liquid in the pressure chamber and a pressure difference that is a difference between the pressure of the liquid in the common supply flow path and the pressure of the liquid in the pressure chamber is a first pressure difference, the adjustment unit has a first cross-sectional area, and when the pressure difference is a second pressure difference that is larger than the first pressure difference, the adjustment unit has a second cross-sectional area that is larger than the first cross-sectional area.

[0006] A liquid ejection device according to one aspect of the present invention includes the liquid ejection head described above, and an ejection control unit that controls an ejection operation for ejecting liquid from the liquid ejection head. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an exploded perspective view showing a liquid ejection head according to a first embodiment. [Diagram 2] 2 is a cross-sectional view of the liquid ejection head, taken along line II-II in FIG. [Diagram 3] FIG. 2 is a plan view showing a nozzle plate. [Figure 4] 4 is a cross-sectional view of the communicating plate, taken along line IV-IV in FIG. 2. [Diagram 5] FIG. 4 is a plan view showing a pressure chamber forming plate. [Figure 6] 3 is an enlarged cross-sectional view showing a main part of a diaphragm and a piezoelectric actuator. FIG. [Figure 7] 3A and 3B are schematic diagrams illustrating the flow of liquid in a liquid ejection head. [Figure 8] FIG. 4 is a cross-sectional view showing a relay flow path in which an adjustment unit is provided. [Figure 9] FIG. 13 is a diagram showing a relay flow path provided with an adjustment unit, as viewed from the inside of a common liquid chamber. [Figure 10]FIG. 11 is a cross-sectional view showing a relay flow path, and is a view showing an adjustment unit during ejection. [Figure 11] 13 is a cross-sectional view showing a relay flow path, and is a diagram showing an adjustment section when pressure is applied from a common liquid chamber. FIG. [Figure 12] FIG. 11 is a cross-sectional view showing a liquid ejection head according to the prior art, illustrating a case where clogging due to particles occurs at the boundary between the relay flow path and the common liquid chamber. [Figure 13] FIG. 2 is a cross-sectional view showing the liquid ejection head in a state where the nozzles are sealed. [Figure 14] FIG. 4 is a cross-sectional view showing a relay flow path of the liquid ejection head according to the first embodiment, illustrating the state of an adjustment section during ejection. [Figure 15] 5 is a cross-sectional view showing a relay flow path of the liquid ejection head according to the first embodiment, illustrating a state of an adjustment section when pressure is applied from a common liquid chamber. FIG. [Figure 16] 11 is a cross-sectional view showing a relay flow path of a liquid ejection head according to a second embodiment. FIG. [Figure 17] 11 is a cross-sectional view showing a relay flow path of a liquid ejection head according to a third embodiment. FIG. [Figure 18] FIG. 11 is a cross-sectional view showing a liquid ejection head according to a second embodiment. [Figure 19] 19 is a cross-sectional view of the communicating plate taken along line XIX-XIX in FIG. 18. [Figure 20] FIG. 11 is a cross-sectional view showing a liquid ejection head according to a third embodiment. [Figure 21] FIG. 11 is a cross-sectional view showing a liquid ejection head according to a third embodiment. [Figure 22] 22 is a cross-sectional view of the communicating plate taken along line XXII-XXII in FIG. 20. [Diagram 23] FIG. 11 is a cross-sectional view showing a liquid ejection head according to a fourth embodiment. [Figure 24] FIG. 13 is a schematic diagram illustrating a liquid ejection device according to a fifth embodiment. [Diagram 25] FIG. 1 is a block diagram showing a liquid ejection device.

[0008] Hereinafter, the embodiments for carrying out the present invention will be described with reference to the drawings. However, in each drawing, the dimensions and scale of each part are appropriately different from the actual ones. In addition, since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are attached, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited.

[0009] In the following description, the three mutually intersecting directions may be described as the X-axis direction, the Y-axis direction, and the Z-axis direction. The X-axis direction includes the X1 direction and the X2 direction, which are opposite directions. The Y-axis direction includes the Y1 direction and the Y2 direction, which are opposite directions. The Z-axis direction includes the Z1 direction and the Z2 direction, which are opposite directions. The Z1 direction is the downward direction, and the Z2 direction is the upward direction. Furthermore, in this specification, the terms "upper" and "lower" are used. "Up" and "lower" correspond to "upper" and "lower" in the normal usage state where the nozzle of the liquid ejection head 20 is at the bottom.

[0010] The X-axis, Y-axis, and Z-axis directions are perpendicular to each other. The Z-axis direction is usually a direction along the vertical direction, but it does not have to be a direction along the vertical direction.

[0011] Fig. 1 is a schematic diagram showing a liquid ejection head 20 according to a first embodiment. Fig. 2 is a cross-sectional view of the liquid ejection head 20, showing a cross section along line II-II in Fig. 1. The liquid ejection head 20 includes a nozzle plate 21, a compliance substrate 23, a communication plate 24, a pressure chamber forming plate 25, a vibration plate 26, and a piezoelectric actuator 50. The liquid ejection head 20 also includes a protection substrate 27, a case 28, and a COF 60. COF is an abbreviation for Chip on Film. The communication plate 24 is an example of a flow path substrate.

[0012] The thickness direction of the nozzle plate 21, the compliance substrate 23, the communication plate 24, the pressure chamber forming plate 25, the vibration plate 26, the protection substrate 27, and the case 28 is along the Z-axis direction. The nozzle plate 21 and the compliance substrate 23 are disposed at the bottom of the liquid ejection head 20. The communication plate 24 is disposed in the Z2 direction of the nozzle plate 21 and the compliance substrate 23. The pressure chamber forming plate 25 is disposed in the Z2 direction of the communication plate 24. The vibration plate 26 is disposed in the Z2 direction of the pressure chamber forming plate 25. A plurality of piezoelectric actuators 50 are formed on the vibration plate 26. The protection substrate 27 is disposed in the Z2 direction of the vibration plate 26. The protection substrate 27 covers the plurality of piezoelectric actuators 50. The case 28 is disposed on the communication plate 24.

[0013] As shown in FIG. 2, the liquid ejection head 20 is formed with a flow path 70 through which ink flows. The flow path 70 includes a supply port 72A, a discharge port 72B, common liquid chambers 73A, 73B, 74A, 74B, relay flow paths 75A, 75B, 76A, 76B, pressure chambers 77A, 77B, communicating flow paths 78A, 78B, 78C, and a nozzle N. The flow path 70 includes a plurality of individual flow paths 71. The individual flow path 71 has a supply side individual flow path 71A and a discharge side individual flow path 71B. The supply side individual flow path 71A may include relay flow paths 75A, 76A, pressure chambers 77A, communicating flow paths 78A, and a part of the communicating flow path 78C. The discharge side individual flow path 71B may include a part of the communicating flow path 78C, the communicating flow path 78B, pressure chambers 77B, and relay flow paths 75B, 76B. The common liquid chambers 73A and 74A are an example of a common supply flow path that is commonly connected to the multiple individual flow paths 71 and supplies liquid to the multiple individual flow paths 71. The common liquid chambers 73B and 74B are an example of a common discharge flow path that is commonly connected to the multiple individual flow paths 71 and discharges liquid flowing in from the multiple individual flow paths 71.

[0014] Ink passes through the supply port 72A and flows into the common liquid chamber 73A. The common liquid chambers 73A and 74A form a common liquid chamber that is in communication with each other. The ink in the common liquid chambers 73A and 74A passes through the relay flow path 75A and is supplied to the pressure chamber 77A. The ink in the pressure chamber 77A passes through the communication flow paths 78A and 78C and is ejected from the nozzle N.

[0015] Of the ink in the communication flow path 78C, the ink that has not been ejected from the nozzle N passes through the communication flow path 78B and flows into the pressure chamber 77B. The ink in the pressure chamber 77 passes through the relay flow path 75B and is discharged into the common liquid chamber 74B. The common liquid chambers 73B, 74B form a common liquid chamber that is in communication with each other. The ink in the common liquid chamber 73B passes through the outlet 72B and is discharged to the outside of the liquid ejection head 20. The flow of ink outside the liquid ejection head 20 will be described later.

[0016] 3 is a plan view showing the nozzle plate 21. The nozzle plate 21 has a rectangular shape when viewed in the Z-axis direction. A plurality of nozzles N are formed in the nozzle plate 21. The plurality of nozzles N are aligned in the Y-axis direction to form a nozzle row N1. The nozzles N are through holes that penetrate the nozzle plate 21 in the Z-axis direction.

[0017] 1 and 2, the compliance substrate 23 is disposed on both sides of the nozzle plate 21 in the X-axis direction. The compliance substrate 23 includes a flexible film. The compliance substrate 23 constitutes the bottom surfaces of the common liquid chambers 74A, 74B. The compliance substrate 23 is deformable when subjected to ink pressure. The compliance substrate 23 deforms due to the ink pressure, and can absorb pressure fluctuations of the ink inside the liquid ejection head 20.

[0018] Fig. 4 is a cross-sectional view showing the communication plate 24. As shown in Fig. 2 and Fig. 4, common liquid chambers 74A, 74B, relay flow paths 75A, 75B, and communication flow paths 78A, 78B, 78C are formed in the communication plate 24. In Fig. 4, the positions of the pressure chambers 77A, 77B, and the nozzles N are indicated by virtual lines.

[0019] The common liquid chambers 74A, 74B are long in the Y-axis direction. The length of the common liquid chambers 74A, 74B in the Y-axis direction corresponds to the arrangement of the multiple nozzles N. The common liquid chamber 74A is arranged so as to overlap with the common liquid chamber 73A when viewed in the Z-axis direction. The common liquid chamber 74A penetrates in the Z-axis direction. The common liquid chamber 74B is arranged so as to overlap with the common liquid chamber 73B when viewed in the Z-axis direction. The common liquid chamber 74B penetrates in the Z-axis direction. The portion of the common liquid chamber 74B closer to the nozzle N is formed to a position overlapping with the pressure chamber 77B when viewed in the Z-axis direction.

[0020] The relay flow paths 75A, 76A communicate between the pressure chamber 77A and the common liquid chamber 74A. The relay flow paths 75A, 76A are provided for each of the multiple pressure chambers 77A. The multiple relay flow paths 75A, 76A are arranged at a predetermined interval in the Y-axis direction. The relay flow path 75A extends in the X-axis direction. The relay flow path 76A extends in the Z-axis direction. The X1-direction end of the relay flow path 75A communicates with the common liquid chamber 74A. The X2-direction end of the relay flow path 75A communicates with the Z1-direction end of the relay flow path 76A. The Z2-direction end of the relay flow path 76A communicates with the pressure chamber 77A.

[0021] The relay flow paths 75B, 76B communicate between the pressure chamber 77B and the common liquid chamber 74B. The relay flow paths 75B, 76B are provided for each of the multiple pressure chambers 77B. The multiple relay flow paths 75B, 76B are arranged at a predetermined interval in the Y-axis direction. The relay flow path 75A extends in the X-axis direction. The relay flow path 76B extends in the Z-axis direction. The X2-direction end of the relay flow path 75B communicates with the common liquid chamber 74A. The X2-direction end of the relay flow path 75B communicates with the Z1-direction end of the relay flow path 76B. The Z2-direction end of the relay flow path 76B communicates with the pressure chamber 77B.

[0022] The communication channels 78A, 78B, and 78C extend in the X-axis direction and communicate between the pressure chambers 77A and 77B. The communication channels 78A, 78B, and 78C are provided for the multiple pressure chambers 77A and 77B, respectively. The multiple communication channels 78A, 78B, and 78C are arranged at predetermined intervals in the Y-axis direction.

[0023] The communicating flow paths 78A and 78B penetrate the communicating plate 24 in the Z-axis direction. The communicating flow paths 78A and 78B are spaced apart in the X-axis direction. The communicating flow path 78A is disposed at a position overlapping with the pressure chamber 77A when viewed in the Z-axis direction. The communicating flow path 78B is disposed at a position overlapping with the pressure chamber 77B when viewed in the Z-axis direction. The communicating flow path 78C extends in the X-axis direction and communicates the communicating flow path 78A with the communicating flow path 78B. The nozzles N are each connected to the multiple communicating flow paths 78C.

[0024] FIG. 5 is a plan view showing the pressure chamber forming plate 25. In FIG. 5, the position corresponding to the nozzle N is shown by a virtual line. As shown in FIG. 2 and FIG. 5, a plurality of pressure chambers 77A, 77B are formed in the pressure chamber forming plate 25. The pressure chambers 77A, 77B penetrate the pressure chamber forming plate 25 in the Z-axis direction. The pressure chambers 77A, 77B are spaced apart in the X-axis direction. The plurality of pressure chambers 77A, 77B are provided for the plurality of nozzles N, respectively. The plurality of pressure chambers 77A are arranged at a predetermined interval in the Y-axis direction. The plurality of pressure chambers 77B are arranged at a predetermined interval in the Y-axis direction. The pressure chamber 77A communicates with the relay flow passage 75A and the communication flow passage 78A. The pressure chamber 77B communicates with the communication flow passage 78B and the relay flow passage 75B. The pressure chamber forming plate 25 can be manufactured from, for example, a single crystal substrate of silicon. The pressure chamber forming plate 25 may be manufactured from other materials.

[0025] 1 and 2, the vibration plate 26 is disposed on the upper surface of the pressure chamber forming plate 25. The vibration plate 26 covers the openings of the pressure chamber forming plate 25. The portions of the vibration plate 26 that cover the openings of the pressure chamber forming plate 25 form the upper wall surfaces of the pressure chambers 77A, 77B. A plurality of piezoelectric actuators 50 are formed on the vibration plate 26. The piezoelectric actuators 50 are provided corresponding to the plurality of pressure chambers 77A, 77B, respectively.

[0026] Fig. 6 is an enlarged cross-sectional view showing the main parts of the vibration plate 26 and the piezoelectric actuator 50. As shown in Fig. 6, the vibration plate 26 is formed of a plurality of insulating layers 26a, 26b. The vibration plate 26 includes an insulating layer 26a made of silicon dioxide (SiO2) and an insulating layer 26b made of zirconium dioxide (ZrO2). The insulating layer 26a is formed on the pressure chamber forming plate 25, and the insulating layer 26b is formed on the insulating layer 26a.

[0027] The diaphragm 26 is driven by the piezoelectric actuator 50 to vibrate in the Z-axis direction. The total thickness of the diaphragm 26 is, for example, 2 μm or less. The total thickness of the diaphragm 26 may be 15 μm or less, 40 μm or less, or 100 μm or less. For example, when the total thickness of the diaphragm 26 is 15 μm or less, the diaphragm 26 may include a resin layer. The diaphragm 26 may be made of a metal. Examples of the metal include stainless steel and nickel. When the diaphragm 26 is made of a metal, the thickness of the diaphragm 26 may be 15 μm or more and 100 μm or less.

[0028] The piezoelectric actuator 50 has electrodes 51 and 52, and a piezoelectric layer 53. The electrode 51, the piezoelectric layer 53, and the electrode 52 are laminated in this order on the vibration plate 26. The piezoelectric layer 53 is sandwiched between the electrodes 51 and 52. The electrode 51 is an individual electrode, and the electrode 52 is a common electrode. The electrode 51 may be a common electrode, and the electrode 52 may be an individual electrode. The electrode 51 is disposed at a position overlapping with each of the pressure chambers 77A and 77B when viewed in the Z-axis direction.

[0029] The electrode 51 includes an underlayer and an electrode layer. The underlayer includes, for example, titanium (Ti). The electrode layer includes, for example, a low-resistance conductive material such as platinum (Pt) or iridium (Ir). The electrode layer may be formed of an oxide such as strontium ruthenate (SrRuO3) or lanthanum nickelate (LaNiO3). The piezoelectric layer 53 is disposed so as to cover the multiple electrodes 51. The piezoelectric layer 53 is a strip-shaped dielectric film extending in the Y-axis direction.

[0030] The electrode 52 includes a base layer and an electrode layer. The base layer includes, for example, titanium. The electrode layer includes, for example, a low-resistance conductive material such as platinum or iridium. The electrode layer may be formed of an oxide such as strontium ruthenate and lanthanum nickelate. In the piezoelectric layer 53, a region between the electrodes 51 and 52 is a driving region. Driving regions are formed on the multiple pressure chambers 77A and 77B, respectively.

[0031] The piezoelectric actuator 50 is electrically connected to a lead electrode 54. The lead electrodes 54 extend in the X-axis direction and are drawn out into the openings 27a of the protective substrate 27. The lead electrodes 54 are not shown in FIGS. 1 and 2. The openings 27a penetrate the protective substrate 27 in the Z-axis direction. As viewed in the Z-axis direction, the lead electrodes 54 are electrically connected to the COF 60 at positions corresponding to the openings 27a. The lead electrodes 54 are formed of a conductive material having a lower resistance than the electrodes 51. For example, the lead electrodes 54 are conductive patterns having a structure in which a conductive film of gold (Au) is laminated on the surface of a conductive film formed of nichrome (NiCr).

[0032] The protective substrate 27 has a rectangular shape when viewed in the Z-axis direction. The protective substrate 27 protects the multiple piezoelectric actuators 50 and reinforces the mechanical strength of the pressure chamber forming plate 25 and the vibration plate 26. The protective substrate 27 is adhered to the vibration plate 26 by, for example, an adhesive.

[0033] The COF 60 includes a flexible wiring board 61 and a driving circuit 62. The flexible wiring board 61 is a wiring board having flexibility. The flexible wiring board 61 is, for example, an FPC. The flexible wiring board 61 may be, for example, an FFC. FPC is an abbreviation for Flexible Printed Circuit. FFC is an abbreviation for Flexible Flat Cable.

[0034] The flexible wiring board 61 is connected to the piezoelectric actuator 50 via the lead electrodes 54. The flexible wiring board 61 is electrically connected to a circuit board (not shown). The circuit board includes a drive signal generating circuit 32 shown in FIG.

[0035] The drive circuit 62 is mounted on the flexible wiring board 61. The drive circuit 62 includes a switching element for driving the piezoelectric actuator 50. The drive circuit 62 is electrically connected to the control unit 30 shown in FIG. 25 via the flexible wiring board 61 and the circuit board. The drive circuit 62 receives the drive signal Com output from the drive signal generation circuit 32. The switching element of the drive circuit 62 switches whether or not the drive signal Com generated by the drive signal generation circuit 32 is supplied to the piezoelectric actuator 50. The drive circuit 62 supplies a drive voltage or current to the piezoelectric actuator 50 to vibrate the diaphragm 26.

[0036] FIG. 7 is a schematic diagram showing the flow path of ink. The liquid ejection device 1 equipped with the liquid ejection head 20 includes a circulation mechanism 8 that circulates the ink. The liquid ejection device 1 will be described later with reference to FIG. 24. The circulation mechanism 8 has a supply flow path 81 that supplies ink to the liquid ejection head 20, and a recovery flow path 82 that recovers ink discharged from the liquid ejection head 20. The circulation mechanism 8 includes a pump 83 connected to the supply flow path 81, and a pump 84 connected to the recovery flow path 82. The pumps 83 and 84 are controlled by the control unit 30. The pump 83 supplies ink from the supply flow path 81 to the liquid ejection head 20. The pump 84 can supply ink from the recovery flow path 82 to the liquid ejection head 20. The liquid ejection device 1 can drive the pump 84 to reverse the ink, for example, during maintenance. This will be described in detail later.

[0037] Next, the adjustment unit 91 provided in the relay flow paths 75A, 75B of the liquid ejection head 20 will be described. As shown in Fig. 2, the liquid ejection head 20 has an adjustment unit 91 that changes the cross-sectional area of ​​the flow path through which liquid flows. The adjustment unit 91 is provided in the relay flow path 75A, and the adjustment unit 92 is provided in the relay flow path 75B. Fig. 8 is a cross-sectional view showing the relay flow path 75A in which the adjustment unit 91 is provided. Fig. 9 is a diagram showing the relay flow path 75A in which the adjustment unit 91 is provided, as viewed from the inside of the common liquid chamber 74.

[0038] The adjustment unit 91 is provided between the pressure chamber 77A and the common liquid chamber 74A in the flow path through which the liquid flows. The adjustment unit 91 includes a plurality of leaf springs 93. The plurality of leaf springs 93 are spaced apart in the Y-axis direction. The adjustment unit 91 changes the cross-sectional area of ​​the flow path between the leaf springs 93. The leaf springs 93 are long in the direction in which the relay flow path 75A extends. The plate thickness direction of the leaf springs 93 intersects with the direction in which the relay flow path 75A extends. The length of the leaf springs 93 along the longitudinal direction is approximately the same as the length of the relay flow path 75A in the X-axis direction. The length of the leaf springs 93 along the longitudinal direction may be shorter than the length of the relay flow path 75A in the X-axis direction. The length of the leaf springs 93 along the Z-axis direction is approximately the same as the length of the relay flow path 75A in the Z-axis direction.

[0039] The leaf spring 93 includes ends 94, 95 spaced apart in the longitudinal direction of the leaf spring 93. The end 94 is the end closer to the common liquid chamber 74A in the X-axis direction. The end 95 is the end farther from the common liquid chamber 74A in the X-axis direction. The end 95 is the end closer to the pressure chamber 77A. The end 94 is a fixed end, and the end 95 is a free end. The end 94 is fixed to the communicating plate 24. The end 94 is fixed to an inner wall surface 96 of the relay flow passage 75A. The inner wall surface 96 is a wall surface that faces the relay flow passage 75A in the Y-axis direction among the wall surfaces that define the relay flow passage 75A. The end 95 may be fixed to another inner wall surface of the communicating plate 24.

[0040] The end 95 is spaced apart from the inner wall surface 96 in the Y-axis direction. The end 95 is displaceable in the Y-axis direction. The end 95 is displaceable in the Y-axis direction so as to approach or move away from the inner wall surface 96. The end 94 is curved when viewed in the Z-axis direction. The end 95 is arranged linearly when viewed in the Z-axis direction. The end 94 may be arranged linearly when viewed in the Z-axis direction. The end 95 may be formed so as to be curved when viewed in the Z-axis direction. The multiple leaf springs 93 face each other in the Y-axis direction. The distance between the end portions 94 of the multiple leaf springs 93 is greater than the distance between the end portions 95.

[0041] The liquid ejection head 20 includes a regulating portion 97 that regulates the displacement of the leaf spring 93 in the plate thickness direction. The regulating portion 97 is provided in the relay flow path 75A. The regulating portion 97 is disposed between the plurality of leaf springs 93 in the Y-axis direction. The regulating portion 97 comes into contact with an end 95 of the leaf spring 93 to regulate the displacement of the end 95. The regulating portion 97 is disposed on, for example, the compliance substrate 23. The regulating portion 97 may be formed on a wall surface of the inner wall surface of the relay flow path 75A that faces the compliance substrate 23 in the Z-axis direction.

[0042] Next, the change in the cross-sectional area of ​​the flow path caused by the adjustment unit 91 will be described with reference to Figs. 10 and 11. Fig. 10 is a cross-sectional view showing the relay flow path, and is a diagram showing the adjustment unit during ejection. Fig. 11 is a cross-sectional view showing the relay flow path, and is a diagram showing the adjustment unit during pressure application from the common liquid chamber. The adjustment unit 91 displaces the leaf spring 93 to change the cross-sectional area of ​​the flow path. The adjustment unit 91 changes the cross-sectional area of ​​the flow path by changing the distances D1, D2 in the Y-axis direction between the ends 95 of multiple leaf springs 93.

[0043] When ejecting liquid, a pressure fluctuation is generated in the liquid in the pressure chamber 77A by the piezoelectric actuator 50. The liquid in the pressure chamber 77A passes through the communicating flow paths 78A, 78C and is ejected from the nozzle N. The pressure of the liquid in the pressure chamber 77A is transmitted to the liquid in the relay flow path 76A on the opposite side to the nozzle N. The pressure of the liquid in the relay flow path 76A is transmitted to the liquid in the relay flow path 75A. The pressure of the liquid in the relay flow path 75A is transmitted to the liquid in the common liquid chambers 73A, 74A.

[0044] When liquid is ejected from the nozzle N, as shown in Fig. 10, the multiple leaf springs 93 are arranged so as to be close to each other in the Y-axis direction. The ends 95 of the leaf springs 93 are close to each other in the Y-axis direction. When the pressure of the liquid in the pressure chamber 77A increases, the distance between the ends 95 does not need to change much. During ejection, the ends 95 abut against the restricting portion 97. During ejection, the displacement of the ends 95 in the direction away from the inner wall surface 96 is suppressed.

[0045] When pressurizing the liquid from the common liquid chambers 73A, 74A, for example, the pump 83 is driven to pressurize the liquid in the common liquid chambers 73A, 74A from the supply port 72A. For example, during maintenance, the liquid can be pressurized from the common liquid chambers 73A, 74A by circulating the liquid. The pressure of the liquid in the common liquid chamber 74A is transmitted to the liquid in the relay flow path 75A. The pressure of the liquid in the relay flow path 75A is transmitted to the liquid in the relay flow path 76A.

[0046] When the liquid in the relay flow passage 75A is pressurized from the common liquid chamber 74, the pressure of the liquid in the relay flow passage 75A displaces the leaf spring 93 to approach the inner wall surface 96 as shown in FIG. 11. The ends 95 of the leaf spring 93 are displaced to move away from each other in the Y-axis direction. The liquid in the relay flow passage 75 pushes the flow passage widen so that the leaf springs 93 are separated from each other. The ends 95 are displaced to move away from the restricting portion 97 and toward the inner wall surface 96. When pressurized from the common liquid chamber 74A, the distance D2 between the ends 95 is greater than the distance D1 shown in FIG. 10. When the pressure of the liquid in the common liquid chamber 74 increases, the distance D2 between the ends 95 becomes even greater. The cross-sectional area of ​​the flow passage between the multiple leaf springs 93 increases in accordance with the increase in pressure in the common liquid chamber 74.

[0047] For example, when the liquid in the common liquid chamber 74A is pressurized to pressure P1, the cross-sectional area of ​​the flow path between the ends 95 of the leaf spring 93 becomes cross-sectional area S1. When the liquid in the common liquid chamber 74A is pressurized to pressure P2, which is higher than pressure P1, the cross-sectional area of ​​the flow path between the ends 95 becomes cross-sectional area S2, which is larger than cross-sectional area S1.

[0048] For example, the cross-sectional area of ​​the flow path between the ends 95 of the leaf spring 93 when the liquid in the pressure chamber 77A is pressurized to pressure P3 is cross-sectional area S3. The cross-sectional area of ​​the flow path between the ends 95 when the liquid in the pressure chamber 77A is pressurized to pressure P4, which is higher than pressure P3, is cross-sectional area S4. The cross-sectional areas S3 and S4 may be the same. Here, "same" includes approximately the same, and includes cases where they can be considered to be substantially the same. The cross-sectional area S4 may be larger than the cross-sectional area S3. The difference between the cross-sectional area S2 and the cross-sectional area S1 is larger than the difference between the cross-sectional area S4 and the cross-sectional area S3.

[0049] Next, clogging of particles 125 in a liquid ejection head 120 according to the conventional technology will be described with reference to Fig. 12. As shown in Fig. 12, the liquid ejection head 120 includes a common liquid chamber 121, a plurality of relay flow paths 122, and a plurality of pressure chambers 123. The liquid in the common liquid chamber 121 passes through the plurality of relay flow paths 122 and is distributed to each of the plurality of pressure chambers 123.

[0050] The cross section of the relay flow passage 122 is narrower than the cross section of the common liquid chamber 121. The "cross section" here refers to a cross section perpendicular to the flow direction of the liquid. In the conventional technology, particles in the liquid may clog the inlet 122a of the relay flow passage 122. The inlet 122a is located at the boundary between the relay flow passage 122 and the common liquid chamber 121. As shown in FIG. 12, in the conventional technology, particles may accumulate at the inlet 122a and clog the flow passage. For example, the particles 125 may accumulate so as to rise toward the inside of the common liquid chamber 121. For example, when the inlet 122a is clogged with particles, even if the pump 83 is used to apply pressure from the common liquid chamber 121, the clog due to the particles may not be eliminated, and the particles 125 may become even more closely attached to each other.

[0051] Similarly, even if a suction pump is connected to the nozzle N and ink is sucked from the nozzle N, the clogging caused by the particles at the inlet 122a is not cleared, and there is a risk that the particles 125 may become even more closely attached to each other. When clogging caused by particles occurs, if liquid is pressurized from the common liquid chamber 121 through the relay flow path 122 toward the pressure chamber 123, only the liquid will flow through the gaps between the particles 125. This flow will cause the particles 125 to become even more closely attached to each other, and there is a risk that the clogging caused by the particles 125 will not be cleared.

[0052] The probability of clogging due to particles 125 is correlated with the ratio between the minimum width W122 of the relay flow path 122 and the particle diameter of the particles 125. The smaller the ratio between the minimum width W122 and the particle diameter, the higher the probability of clogging due to particles 125. For example, in order to reduce the probability of clogging due to particles, it is desirable to set the minimum width W122 to be 10 times or more the particle diameter. However, if the minimum width W122 of the relay flow path 122 is increased, when the liquid in the pressure chamber 123 is pressurized to eject the liquid, the pressure of the liquid in the pressure chamber 123 escapes through the relay flow path 122 to the common liquid chamber 121, causing a problem that the liquid cannot be efficiently ejected from the nozzle N.

[0053] According to the liquid ejection head 20 of this embodiment, the adjustment unit 91 that changes the cross-sectional area of ​​the flow path is provided in the relay flow path 75A, so that the cross-sectional area of ​​the flow path can be changed between the pressure chamber 77A and the common liquid chamber 74A. In the liquid ejection head 20, the cross-sectional area of ​​the flow path can be changed when the liquid is ejected from the nozzle N and when pressure is applied from the common liquid chamber 74A. In the liquid ejection head 20, the cross-sectional area of ​​the flow path can be made wider when pressure is applied from the common liquid chamber 74A, and the cross-sectional area of ​​the flow path can be made narrower when the liquid is ejected than when pressure is applied from the common liquid chamber 74A. In the liquid ejection head 20, when liquid is flowed from the common liquid chamber 74A into the pressure chamber 77A, the cross-sectional area of ​​the flow path can be made larger by the adjustment unit 91, so that the probability of clogging due to particles can be reduced. In the liquid ejection head 20, the cross-sectional area of ​​the flow path can be narrowed by the adjustment unit 91 when ejecting, so that the pressure of the liquid can be made less likely to escape into the common liquid chamber 74A. In the liquid ejection head 20, the piezoelectric actuator 50 is driven to increase the pressure in the pressure chamber 77A, thereby enabling the liquid to be ejected reliably from the nozzle N. In the liquid ejection head 20, clogging of the flow path due to particles is suppressed, and the liquid can be ejected reliably from the nozzle N.

[0054] In the liquid ejection head 20, for example, during maintenance, liquid can be circulated from the common liquid chambers 73A and 74A toward the pressure chamber 77A to pressurize the liquid in the relay flow path 75A from the common liquid chamber 74A. During this pressurization, the liquid in the common liquid chamber 74A can be pressurized with pressure P2 higher than pressure P1 to increase the distance between the leaf springs 93 and increase the cross-sectional area of ​​the flow path between the leaf springs 93. The cross-sectional area of ​​the flow path between the leaf springs 93 increases, for example, from cross-sectional area S1 to cross-sectional area S2. In the liquid ejection head 20, pressurization from the common liquid chamber 74A during maintenance can suppress clogging due to particles.

[0055] In the liquid ejection head 20, the piezoelectric actuator 50 is driven to change the pressure of the liquid in the pressure chambers 77A and 77B, and the liquid can be ejected from the nozzle N. When the pressure of the liquid in the pressure chamber 77A changes from pressure P3 to pressure P higher than pressure P3, the cross-sectional area of ​​the flow path between the leaf springs 93 changes from cross-sectional area S3 to cross-sectional area S4. The change from cross-sectional area S3 to cross-sectional area S4 is smaller than the change from cross-sectional area S1 to cross-sectional area S2. The change in the cross-sectional area of ​​the flow path of the adjustment unit 91 when pressure is applied from the pressure chamber 77A is smaller than the change in the cross-sectional area of ​​the flow path of the adjustment unit 91 when pressure is applied from the common liquid chamber 74A. As a result, in the liquid ejection head 20, the pressure drop in the pressure chamber 77A is suppressed and the liquid can be reliably ejected from the nozzle N.

[0056] The adjustment unit 91 can change the cross-sectional area of ​​the flow path to a cross-sectional area S1 when the pressure of the liquid in the common liquid chamber 74A is higher than the pressure in the pressure chamber 77A and a pressure difference ΔP between the pressure in the common liquid chamber 74A and the pressure of the liquid in the pressure chamber 77A is a first pressure difference ΔP1. The adjustment unit 91 can change the cross-sectional area of ​​the flow path to a second cross-sectional area S2 larger than the first cross-sectional area S1 when the pressure difference ΔP is a second pressure difference ΔP2 larger than the first pressure difference ΔP1. The adjustment unit 91 can adjust the cross-sectional area of ​​the flow path in this manner.

[0057] The adjustment unit 91 changes the cross-sectional area so that when the pressure of the liquid in the pressure chamber 77A is higher than the pressure of the liquid in the common liquid chamber 74A and the pressure difference ΔP is the third pressure difference ΔP3, the cross-sectional area of ​​the flow path by the adjustment unit 91 becomes the third cross-sectional area S3, and when the pressure difference ΔP is the fourth pressure difference ΔP4 larger than the third pressure difference ΔP3, the cross-sectional area becomes the fourth cross-sectional area S4. In this case, the difference between the third cross-sectional area S3 and the fourth cross-sectional area S4 is smaller than the difference between the first cross-sectional area S1 and the second cross-sectional area S2. The third cross-sectional area S3 is approximately equal to the fourth cross-sectional area S4. The third cross-sectional area S3 may be equal to the fourth cross-sectional area S4. The difference between the third pressure difference ΔP3 and the fourth pressure difference ΔP4 is approximately equal to the difference between the first pressure difference ΔP1 and the second pressure difference ΔP2. The difference between the third pressure difference ΔP3 and the fourth pressure difference ΔP4 may be equal to the difference between the first pressure difference ΔP1 and the second pressure difference ΔP2.

[0058] Next, with reference to Fig. 13, a case where pressure is applied from the common liquid chambers 73A, 74A with the nozzles N sealed will be described. Fig. 13 is a cross-sectional view showing the liquid ejection head 20 with the nozzles N sealed. The liquid ejection device 1 equipped with the liquid ejection head 20 may be equipped with a sealing portion 85 that seals the nozzles N. The sealing portion 85 has a surface 85a that comes into contact with the nozzle surface 21a of the nozzle plate 21. The surface 85a comes into contact with the nozzle surface 21a to seal the nozzles N. The surface 85a has a predetermined length in the Y-axis direction and can cover a plurality of nozzles N.

[0059] The liquid ejection device 1 can circulate the liquid with the nozzles N sealed by the sealing portion 85 during maintenance, for example. The liquid is supplied from the supply port 72A into the liquid ejection head 20. The liquid that has passed through the flow path 70 is discharged from the discharge port 72B. The liquid discharged from the discharge port 72B is again supplied from the supply port 72A into the liquid ejection head 20. In this case, since the nozzles N are sealed, the liquid can be circulated at a higher pressure than when the nozzles N are not sealed. By applying pressure from the common liquid chamber 74A at a higher pressure, the cross-sectional area can be made larger, so clogging due to particles can be suppressed. In addition, the liquid ejection device 1 may reverse the direction in which the liquid flows. The liquid ejection device 1 may alternate between a forward flow in which the liquid flows from the supply port 72A and a reverse flow in which the liquid flows from the discharge port 72B. By changing the direction of the liquid flowing in the flow path 70 to the opposite direction, pressure can be applied from a different direction.

[0060] In the conventional technology, there is a restriction on the particle diameter of the particles contained in the liquid in order to prevent clogging by the particles. However, in the liquid ejection device 1, clogging by the particles is suppressed, so it is possible to use a liquid containing particles with a larger particle diameter than in the conventional technology. Similarly, in the conventional technology, there is a restriction on the concentration of particles contained in the liquid in order to prevent clogging by the particles. However, in the liquid ejection head 20, clogging by the particles is suppressed, so it is possible to use a liquid with a higher concentration of particles than in the conventional technology.

[0061] Next, the average particle diameter of the coloring material contained in the liquid will be described. The average particle diameter of the coloring material contained in the liquid is, for example, 2 μm or more. It is more preferably 4.5 μm or more. The average particle diameter of the coloring material contained in the liquid is, for example, 10 μm or less. The average particle diameter can be calculated, for example, using a particle diameter measurement method according to JIS Z8825. The average particle diameter may also be a value measured using other methods such as image analysis and centrifugal sedimentation. Since the liquid ejection device 1 can suppress clogging due to particles, it is possible to use a liquid containing particles with a larger particle diameter than in the past.

[0062] Next, a liquid ejection head 20 including an adjustment unit 91 according to Example 1 will be described with reference to Figs. 14 and 15. Figs. 14 and 15 are cross-sectional views showing a relay flow path 75A of the liquid ejection head 20 including the adjustment unit 91 according to Example 1. Fig. 14 is a diagram showing the state of the adjustment unit 91 during ejection. Fig. 15 is a diagram showing the state of the adjustment unit 91 when pressure is applied from the common liquid chamber 74A. The adjustment unit 91 according to Example 1 includes an elastically deformable filler 98.

[0063] The filler 98 is disposed between the leaf spring 93 and an inner wall surface 96 of the relay flow passage 75A. The inner wall surface 96 is an inner wall surface 96 that exists in the direction in which the leaf spring 93 moves when the cross-sectional area of ​​the flow passage is expanded. The filler 98 contacts the end portion 95 and the inner wall surface 96. The filler 98 is formed of, for example, a flexible silicone resin. The filler 98 seals the gap between the leaf spring 93 and the inner wall surface 96. The filler 98 elastically deforms in accordance with the displacement of the leaf spring 93.

[0064] When liquid is ejected from the nozzle N, the leaf spring 93 is displaced so as to move away from the inner wall surface 96, and the filler 98 is expanded, as shown in Fig. 14. When liquid is pressurized from the common liquid chamber 74A, the leaf spring 93 is displaced so as to approach the inner wall surface 96, and the filler 98 is compressed, as shown in Fig. 15.

[0065] The adjustment unit 91 according to the first embodiment includes the filler 98, which prevents liquid from entering the gap between the inner wall surface 96 and the leaf spring 93. This prevents liquid from staying in the dead space between the leaf spring 93 and the inner wall surface 96. For example, particles contained in the liquid are prevented from entering the gap between the leaf spring 93 and the inner wall surface 96.

[0066] Next, a liquid ejection head 20 including an adjustment unit 101 according to Example 2 will be described with reference to Fig. 16. Fig. 16 is a cross-sectional view showing a relay flow path 75A of the liquid ejection head 20 including the adjustment unit 101 according to Example 2. The liquid ejection head 20 may include the adjustment unit 101 instead of the adjustment unit 91. The adjustment unit 101 includes a plurality of leaf springs 103.

[0067] The leaf spring 103 is elongated in the X-axis direction. The thickness direction of the leaf spring 103 is generally along the Y-axis direction. The thickness direction of the leaf spring 103 may be along other directions. The leaf spring 103 has ends 104, 105 spaced apart in the longitudinal direction. The end 104 is the end closer to the common liquid chamber 74A. The end 105 is the end farther from the common liquid chamber 74A. The end 105 is the end closer to the pressure chamber 77A. The ends 104 and 105 are fixed ends and are fixed to the inner wall surface 96. The ends 104 and 105 are fixed to the communicating plate 24.

[0068] The leaf spring 103 is curved when viewed from the Z-axis direction. A central portion 106 in the longitudinal direction of the leaf spring 103 is spaced from the inner wall surface 96. The cross-sectional area between the central portions 106 of the plurality of leaf springs 103 is the narrowest in the flow path of the adjustment unit 101. The central portion 106 is displaced so as to approach or move away from the inner wall surface 96. For example, when the pressure of the liquid in the common liquid chamber 74A increases from the first pressure P1 to the second pressure P2, the central portion 106 is displaced so as to approach the inner wall surface 96. The leaf spring 103 is deformed so that the cross-sectional area of ​​the flow path of the adjustment unit 101 increases. For example, when the pressure of the liquid in the common liquid chamber 74A decreases from the second pressure P2 to the first pressure P1, the central portion 106 is displaced so as to move away from the inner wall surface 96. The leaf spring 103 deforms so as to reduce the cross-sectional area of ​​the flow path of the adjustment unit 101. In the liquid ejection head 20, for example, when clogging due to particles occurs, the cross-sectional area of ​​the flow path can be changed by applying pressure from the common liquid chamber 74A, thereby eliminating the clogging due to particles.

[0069] Next, referring to FIG. 17, a liquid ejection head 20 including an adjustment unit 91C according to a third embodiment will be described. FIG. 17 is a cross-sectional view showing a relay flow path 75A of a liquid ejection head 20 including an adjustment unit 91C according to a third embodiment. The liquid ejection head 20 may include an adjustment unit 91C instead of the adjustment unit 91. The adjustment unit 91C differs from the adjustment unit 91 in that it includes only one leaf spring 93. In this way, the adjustment unit 91C may include one leaf spring 93. The direction in which the leaf spring 93 is displaced is not limited to the Y-axis direction, and may be other directions. For example, the leaf spring 93 may be fixed to a surface of the inner wall surface of the relay flow path 75A that intersects with the Z-axis direction, and displaced in the Z-axis direction.

[0070] Next, a liquid ejection head 20B according to a second embodiment will be described with reference to Figs. 18 and 19. Fig. 18 is a cross-sectional view showing a liquid ejection head 20B according to a second embodiment liquid. Fig. 19 is a cross-sectional view of a communication plate, showing a cross section along line XIX-XIX in Fig. 18. The liquid ejection head 20B according to the second embodiment differs from the liquid ejection head 20 according to the first embodiment in that an adjustment unit 92 is provided in the relay flow path 75B. Note that in the description of the second embodiment, the same description as in the above first embodiment will be omitted.

[0071] The adjustment portion 92 includes a plurality of leaf springs 93. The adjustment portion 92 has substantially the same configuration as the adjustment portion 91, except for its arrangement. An end 94 of the leaf spring 93 is the end closer to the common liquid chamber 74B. An end 95 of the leaf spring 93 is the end farther from the common liquid chamber 74B. A restricting portion 97 is disposed between the ends 95 of the plurality of leaf springs 93.

[0072] For example, when the liquid in the common liquid chamber 74B is pressurized to pressure P1, the cross-sectional area of ​​the flow path between the ends 95 of the leaf spring 93 becomes cross-sectional area S1. When the liquid in the common liquid chamber 74B is pressurized to pressure P2, which is higher than pressure P1, the cross-sectional area of ​​the flow path between the ends 95 becomes cross-sectional area S2, which is larger than cross-sectional area S1.

[0073] For example, when the liquid in pressure chamber 77B is pressurized to pressure P3, the cross-sectional area of ​​the flow path between ends 95 of leaf spring 93 is cross-sectional area S3. When the liquid in pressure chamber 77B is pressurized to pressure P4, which is higher than pressure P3, the cross-sectional area of ​​the flow path between ends 95 is cross-sectional area S4. Cross-sectional area S3 and cross-sectional area S4 may be the same. Here, "same" includes approximately the same, and includes cases where they can be considered to be substantially the same. Cross-sectional area S4 may be larger than cross-sectional area S3. The difference between cross-sectional area S2 and cross-sectional area S1 is larger than the difference between cross-sectional area S4 and cross-sectional area S3.

[0074] According to the liquid ejection head 20B of the second embodiment, the relay flow path 75A is provided with an adjustment unit 91, and the relay flow path 75B is provided with an adjustment unit 92, so that the cross-sectional area of ​​the flow path can be changed to suppress clogging due to particles. In the liquid ejection head 20B, pressure is applied from the common liquid chamber 74A to expand the cross-sectional area of ​​the flow path by the adjustment unit 91, and pressure is applied from the common liquid chamber 74B to expand the cross-sectional area of ​​the flow path by the adjustment unit 92, thereby changing the flow rate and suppressing clogging due to particles.

[0075] Next, a liquid ejection head 20C according to a third embodiment will be described with reference to Figs. 20 to 22. Figs. 20 and 21 are cross-sectional views showing the liquid ejection head 20C according to the third embodiment. Fig. 22 is a cross-sectional view showing the communication plate 24B of the liquid ejection head 20C, taken along line XIX-XIX in Fig. 20. The liquid ejection head 20C of the third embodiment differs from the liquid ejection head 20 of the first embodiment in that one pressure chamber is provided for one individual flow path. Note that in the description of the second embodiment, the same description as in the first embodiment will be omitted.

[0076] The liquid ejection head 20C includes a communication plate 24B and a pressure chamber forming plate 25B. The liquid ejection head 20C includes a plurality of individual flow paths 170A and 170B. FIG. 20 shows the individual flow path 170A, and FIG. 21 shows the individual flow path 170B. The individual flow paths 170A and 170B are alternately arranged in the Y-axis direction. The individual flow path 170A shown in FIG. 20 includes relay flow paths 75A and 76A, a pressure chamber 77A, and communication flow paths 78A, 78C, and 78D. The communication flow path 78D extends in the X-axis direction and communicates the communication flow path 78C with the common liquid chamber 74B. The individual flow path 170B shown in FIG. 21 includes relay flow paths 75B and 76B, a pressure chamber 77B, and communication flow paths 78B, 78C, and 78E. The communication flow path 78E extends in the X-axis direction and communicates the common liquid chamber 74A with the communication flow path 78C. The common liquid chambers 74A and 74B, the relay flow paths 75A and 75B, and the communication flow paths 78A to 78E are formed in the communication plate 24B. The pressure chambers 77A and 77B are formed in the pressure chamber forming plate 25B. The relay flow path 75A is provided with an adjustment section 91, and the relay flow path 75B is provided with an adjustment section 92. The adjustment sections 91 and 92 are configured as described above, and therefore, description thereof will be omitted here. In the liquid ejection head 20C, the common liquid chambers 73A and 74A are an example of a first common supply flow path. The common liquid chambers 73B and 74B are an example of a second common supply flow path. The adjustment section 91 is an example of a first adjustment section, and the adjustment section 92 is an example of a second adjustment section.

[0077] The liquid ejection head 20C of the third embodiment also provides the same effects as the liquid ejection heads 20 and 20B of the above embodiments.

[0078] Next, a liquid ejection head 20D according to a fourth embodiment will be described with reference to Fig. 23. Fig. 23 is a cross-sectional view showing a liquid ejection head 20D according to the fourth embodiment. The liquid ejection head 20D according to the fourth embodiment differs from the liquid ejection head 20 according to the first embodiment in that it does not include a flow path on the discharge side. Note that in the description of the fourth embodiment, the same description as in the first embodiment may be omitted.

[0079] A liquid flow path 70 of the liquid ejection head 20D includes a supply port 72A, common liquid chambers 73A, 74A, relay flow paths 75A, 76A, a pressure chamber 77A, a communicating flow path 78A, and a nozzle N. The communicating flow path 78A communicates between the pressure chamber 77A and the nozzle N. The flow path 70 includes an individual flow path 71. The individual flow path 71 includes a relay flow path 75A, a pressure chamber 77A, a communicating flow path 78A, and a nozzle N.

[0080] The relay flow passage 75A is provided with an adjustment section 91. The adjustment section 91 has a plurality of leaf springs 93. In the liquid ejection head 20D according to the fourth embodiment, when pressure is applied from the common liquid chamber 74A, the plurality of leaf springs 93 can be displaced to expand the cross-sectional area of ​​the flow passage. This makes it possible to suppress clogging of the flow passage by particles. In the liquid ejection head 20D, during ejection, the piezoelectric actuator 50 generates pressure fluctuations in the liquid in the pressure chamber 77A, and the liquid can be ejected from the nozzle N. During ejection, the flow passage between the plurality of leaf springs 93 can be kept narrow without being expanded, so that the pressure of the liquid in the pressure chamber 77A does not escape to the common liquid chamber 74A. This makes it possible to eject the liquid reliably from the nozzle N. In the liquid ejection head 20D, the same effects as those of the liquid ejection heads 20, 20B, and 20C of the above-mentioned embodiments can be achieved.

[0081] Next, referring to FIG. 24 and FIG. 25, a liquid ejection device 1 according to a fifth embodiment will be described. The liquid ejection device 1 includes the above-mentioned liquid ejection head 20. In the description of the fifth embodiment, the same description as in the above-mentioned embodiments will be omitted. FIG. 24 is a schematic diagram showing the liquid ejection device 1 according to the fifth embodiment. FIG. 25 is a block diagram showing the liquid ejection device 1. The liquid ejection device 1 is an inkjet printing device that ejects ink, which is an example of a "liquid," as droplets onto a medium PA. The liquid ejection device 1 is a serial printing device. The medium PA is typically a printing paper. In addition, the medium PA is not limited to a printing paper, and may be a printing target of any material, such as a resin film or a fabric.

[0082] The liquid ejection device 1 includes a liquid ejection head 20 that ejects ink, a liquid container 2 that stores ink, a carriage 3 that mounts the liquid ejection head 10, a carriage transport mechanism 4 that transports the carriage 3, a medium transport mechanism 5 that transports the medium PA, and a control unit 30. As described above, the liquid ejection device 1 includes a circulation mechanism 8 that circulates the ink. The control unit 30 is an example of an ejection control unit.

[0083] Specific examples of the liquid container 2 include a cartridge that is detachable from the liquid ejection device 1, a bag-shaped ink pack made of a flexible film, and an ink tank that can be refilled with ink. Any type of ink may be stored in the liquid container 2. The liquid ejection device 1 includes a plurality of liquid containers 2 corresponding to, for example, four colors of ink. The four colors of ink include, for example, cyan, magenta, yellow, and black. The liquid container 2 may be mounted on a carriage 3.

[0084] The carriage transport mechanism 4 has a transport belt 4a and a motor for transporting the carriage 3. The medium transport mechanism 5 has a transport roller 5a and a motor for transporting the medium PA. The carriage transport mechanism 4 and the medium transport mechanism 5 are controlled by a control unit 30. The liquid ejection device 1 ejects ink droplets onto the medium PA by transporting the carriage 3 using the carriage transport mechanism 4 while transporting the medium PA using the medium transport mechanism 5, thereby printing.

[0085] 25, the liquid ejection device 1 includes a linear encoder 6. The linear encoder 6 is provided at a position where the position of the carriage 3 can be detected. The linear encoder 6 obtains information regarding the position of the carriage 3. The linear encoder 6 outputs an encoder signal to the control unit 30 as the carriage 3 moves.

[0086] The control unit 30 shown in FIG. 2 includes one or more CPUs 31. The control unit 30 may include an FPGA instead of or in addition to the CPU 31. The control unit 30 includes a storage unit 40. The storage unit 40 includes, for example, a ROM 41 and a RAM 42. The storage unit 40 may include an EEPROM or a PROM. The storage unit 40 can store print data Img supplied from a host computer. The storage unit 40 stores a control program for the liquid ejection device 1.

[0087] CPU is an abbreviation for Central Processing Unit. FPGA is an abbreviation for field-programmable gate array. RAM is an abbreviation for Random Access Memory. ROM is an abbreviation for Read Only Memory. EEPROM is an abbreviation for Electrically Erasable Programmable Read-Only Memory. PROM is an abbreviation for Programmable ROM.

[0088] The control unit 30 generates signals for controlling the operation of each part of the liquid ejection device 1. The control unit 30 can generate a print signal SI and a waveform designation signal dCom. The print signal SI is a digital signal for designating the type of operation of the liquid ejection head 20. The print signal SI can designate whether or not to supply a drive signal Com to the piezoelectric actuator 50. The waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the piezoelectric actuator 50.

[0089] As described above, the liquid ejection device 1 includes the drive signal generation circuit 32. The drive signal generation circuit 32 is electrically connected to the control unit 30. The drive signal generation circuit 32 includes a DA conversion circuit. The drive signal generation circuit 32 generates a drive signal Com having a waveform defined by a waveform designation signal dCom. When the control unit 30 receives an encoder signal from the linear encoder 6, the control unit 30 outputs a timing signal PTS to the drive signal generation circuit 32. The timing signal PTS defines the generation timing of the drive signal Com. The drive signal generation circuit 32 outputs the drive signal Com every time it receives the timing signal PTS.

[0090] The drive circuit 62 is electrically connected to the control unit 30 and the drive signal generation circuit 32. The drive circuit 62 switches whether or not to supply the drive signal Com to the piezoelectric actuator 50 based on the print signal SI. The drive circuit 62 can select the piezoelectric actuator 50 to which the drive signal Com is supplied based on the print signal SI, latch signal LAT, and change signal CH supplied from the control unit 30. The latch signal LAT defines the latch timing of the print data Img. The change signal CH defines the selection timing of the drive pulse included in the drive signal Com.

[0091] The control unit 30 controls the ink ejection operation by the liquid ejection head 20. As described above, the control unit 30 drives the piezoelectric actuator 50 to vary the pressure of the ink in the pressure chambers 77A, 77B and eject ink from the nozzles N. The control unit 30 controls the ejection operation when performing a printing operation. The control unit 30 may also control the ejection operation when performing a maintenance operation. As a maintenance operation, the control unit 30 can eject ink from the nozzles N before or after printing to suppress thickening of the ink in the liquid ejection head 20.

[0092] The control unit 30 controls the operation of circulating the ink during maintenance. For example, the control unit 30 can drive the pump 83 while the nozzle N is sealed to supply ink from the supply port 72A into the liquid ejection head 20 and pressurize the ink from the common liquid chambers 73A and 74A. In this way, the control unit 30 can pressurize the ink in the relay flow path 75A from the common liquid chamber 74A to displace the multiple leaf springs 93 and change the cross-sectional area of ​​the flow path by the adjustment unit 91. The control unit 30 may also drive the pump 84 to supply ink from the discharge port 72B into the liquid ejection head 20 and control the operation of circulating the ink.

[0093] Since the liquid ejection device 1 includes the liquid ejection head 20, clogging due to particles can be suppressed by changing the cross-sectional area of ​​the flow path by the adjustment unit 91. Note that the liquid ejection device 1 may be configured to include liquid ejection heads 20B, 20C, and 20D instead of the liquid ejection head 20.

[0094] It should be noted that the above-described embodiment merely illustrates a typical form of the present invention, and the present invention is not limited to the above-described embodiment, and various modifications and additions are possible without departing from the gist of the present invention.

[0095] The above-described embodiment illustrates a serial type liquid ejection device 1 in which a carriage 3 carrying a liquid ejection head 20 is moved back and forth in the width direction of the medium PA, but the present invention may also be applied to a line type liquid ejection device equipped with a line head in which the liquid ejection heads 20 are arranged in a predetermined direction.

[0096] In the above-described liquid ejection device 1, while the nozzles N are sealed, a pressurizing operation is performed using the pump 84 to pressurize the liquid in the direction from the pressure chamber 77A toward the common liquid chamber 74A, but the means for pressurizing the liquid in the pressurizing operation is not limited to a pump. For example, the pressurizing operation may be performed using other pressure increasing means. In addition, the pressurizing operation by the pump 84 and the pressurizing operation by the piezoelectric actuator 50 may be performed alternately on the liquid ejection head 20. In addition, the pressurizing operation by the pump 84 and the pressurizing operation by the piezoelectric actuator 50 may be performed simultaneously on the liquid ejection head 20.

[0097] The liquid ejection device 1 exemplified in the above-mentioned embodiment can be adopted in various devices such as facsimile machines and copy machines, in addition to devices dedicated to printing. However, the use of the liquid ejection device of the present invention is not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming a color filter of a display device such as a liquid crystal display panel. Also, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes of a wiring board. Also, a liquid ejection device that ejects a solution of an organic substance related to a living body is used as a manufacturing device for manufacturing a biochip, for example.

[0098] In the above description, the average particle diameter of the particles contained in the liquid is exemplified as 2 μm or more, but the average particle diameter of the particles contained in the liquid is not limited to this. For example, when environmental resistance is taken into consideration, the larger the average particle diameter, the better. Environmental resistance includes light resistance and water resistance. For example, when granularity is taken into consideration, the smaller the average particle diameter, the better.

[0099] For example, when the liquid ejection device applies bio-related liquid, the liquid may contain particles such as artificial red blood cells. The diameter of a red blood cell is, for example, about 7 to 8 μm, and the thickness of a red blood cell is about 2 μm. The liquid ejection device 1 may be used, for example, in a manufacturing process of artificial red blood cells. For example, the liquid ejection device 1 is expected to be used for manufacturing artificial blood with higher accuracy than before.

[0100] Examples of particles contained in the liquid used in the liquid ejection device 1 include metallic pigments. For example, to produce a silver color, it is necessary to reflect all wavelengths in the visible light range, and therefore a flat surface with a size sufficiently larger than the wavelength is required. Since visible light is approximately 0.4 to 0.7 μm, it is desirable for the average particle size to be sufficiently larger than that, that is, 2 μm or more. The liquid ejection device 1 may eject a liquid containing a metallic pigment with an average particle size of 2 μm or more.

[0101] An example of the particles contained in the liquid used in the liquid ejection device 1 is a pearlescent pigment. Similar to the metallic pigment, the pearlescent pigment is reproduced by reflecting multiple layers of leaf-shaped mica at intervals, so a size one size larger than that of the metallic pigment is desired. The liquid ejection device 1 may eject a liquid containing a pearlescent pigment with an average particle diameter of 2 μm or more.

[0102] The liquid ejection device 1 may be applied to metal wiring and die bonding. A paste of silver particles is used to bond metal wiring and IC chips. In recent years, the use of silver particles of several nm level has been increasing, but there are concerns about the increase in environmental load and the impact on the human body in the manufacturing process of nano silver particles. For example, it has been reported that there is a correlation between particle size and viscosity when the particle concentration is increased, and that the viscosity of the liquid tends to increase significantly especially when the particle size is 1 μm or less. In order to make a high-concentration dispersion liquid have a viscosity that can be ejected from the liquid ejection device 1, it is desirable for the average particle diameter to be 2 μm or more.

[0103] The liquid ejection device 1 may be used in technical fields such as liquid crystal and adhesive gap agents. In order to ensure the cell gap of the liquid crystal and adhesive strength, it is desirable to precisely apply an adhesive containing particles of, for example, about 2 to 10 μm. [Explanation of symbols]

[0104] 1...liquid ejection device, 20, 20B, 20C, 20D...liquid ejection head, 24, 24B...communicating plate (flow path substrate), 30...control section (ejection control section), 50...piezoelectric actuator, 71...individual flow path, 73A, 74A...common liquid chamber (common supply flow path, first common supply flow path), 73B, 74B...common liquid chamber (common discharge flow path, second common supply flow path), 75A, 75B...relay flow path (individual flow path), 77A, 77B...pressure chamber, 91, 91C...adjustment section (first adjustment section), 92... Adjustment section (second adjustment section), 93...leaf spring, 94...end section (end section closer to the common supply flow path, fixed end), 95...end section (end section closer to the pressure chamber, free end), 96...inner wall surface (wall surface of individual flow path), 97...regulation section, 98...filler, 101...adjustment section, 103...leaf spring, 104...end section (end section closer to the common supply flow path, fixed end), 105...end section (end section closer to the pressure chamber, fixed end), N...nozzle, PA...medium, X...X-axis direction (first direction), Y...Y-axis direction (second direction).

Claims

1. A liquid ejection head that ejects liquid from a nozzle, A plurality of individual flow paths including pressure chambers communicating with the nozzles; a common supply flow path that is commonly connected to the individual flow paths and supplies liquid to the individual flow paths; The road, A flow passage for changing a cross-sectional area of ​​a flow passage through which a liquid flows is provided between the pressure chamber and the common supply flow passage. and an adjustment unit for adjusting the When the adjustment portion is pressurized with a first pressure difference from the common supply flow path toward the pressure chamber, the cross-sectional area is a first cross-sectional area, The adjustment unit is configured to adjust the pressure difference from the common supply flow path toward the pressure chamber so as to be greater than the first pressure difference. When pressurizing with a second pressure difference, the cross-sectional area is a second cross-sectional area larger than the first cross-sectional area. And, When the adjustment portion is pressurized with a third pressure difference from the pressure chamber toward the common supply flow path, the cross-sectional area is a third cross-sectional area, The pressure difference of the adjustment unit is greater than the third pressure difference from the pressure chamber toward the common supply flow path. When pressurized with a fourth pressure difference, the cross-sectional area becomes a fourth cross-sectional area, The difference between the third pressure difference and the fourth pressure difference is equal to the difference between the first pressure difference and the second pressure difference. equally, The difference between the third cross-sectional area and the fourth cross-sectional area is greater than the difference between the first cross-sectional area and the second cross-sectional area. A liquid ejection head that is smaller than conventional liquid ejection heads.

2. The liquid ejection head according to claim 1 , wherein the third cross-sectional area is equal to the fourth cross-sectional area.

3. A liquid ejection head that ejects liquid from a nozzle, A plurality of individual flow paths including pressure chambers communicating with the nozzles; a common supply flow path that is commonly connected to the individual flow paths and supplies liquid to the individual flow paths; The road, a common exhaust pipe which is commonly connected to the individual flow paths and through which liquid is discharged from the individual flow paths; An outlet path; A flow passage for changing a cross-sectional area of ​​a flow passage through which a liquid flows is provided between the pressure chamber and the common supply flow passage. and an adjustment unit for adjusting the When the adjustment portion is pressurized with a first pressure difference from the common supply flow path toward the pressure chamber, the cross-sectional area is a first cross-sectional area, The adjustment unit is configured to adjust the pressure difference from the common supply flow path toward the pressure chamber so as to be greater than the first pressure difference. When pressurizing with a second pressure difference, the cross-sectional area is a second cross-sectional area larger than the first cross-sectional area. And, An adjustment section for changing the cross-sectional area of ​​the flow passage is provided between the pressure chamber and the common discharge flow passage. Uninsulated liquid ejection head.

4. The adjustment portion has a leaf spring, The end of the leaf spring closer to the common supply flow path is a fixed end, 4. The method according to claim 1, wherein the end of the leaf spring closer to the pressure chamber is a free end. Item 5. A liquid ejection head according to item 1.

5. The adjustment portion has a leaf spring, The end of the leaf spring closer to the common supply flow path is a fixed end, 4. The method according to claim 1, wherein the end of the leaf spring closer to the pressure chamber is a fixed end. Item 1. A liquid ejection head according to item 1.

6. a flow path substrate on which at least a part of the common supply flow path is formed; The fixed end of the leaf spring, which is the end closer to the common supply flow channel, is fixed to the flow channel substrate.

6. The liquid ejection head according to claim 4, wherein

7. A plurality of the leaf springs are provided for each of the individual flow paths, The plurality of leaf springs are spaced apart from each other in a second direction perpendicular to a first direction along the individual flow paths. Item 7. The liquid ejection head according to any one of items 4 to 6.

8. 8. The method according to claim 4, further comprising: a restricting portion for restricting the displacement of the leaf spring in a thickness direction.

3. The liquid ejection head according to claim 1.

9. The individual springs that exist in a direction in which the leaf spring moves when the cross-sectional area of ​​the flow path is expanded. The spring further includes an elastically deformable filler disposed in a gap between a wall surface of the flow path and the leaf spring. The liquid ejection head according to claim 4 .

10. A first common supply flow path which is the common supply flow path; A first adjustment unit which is the adjustment unit; the first common nozzle is connected in common to the plurality of individual flow paths and supplies a liquid to the plurality of individual flow paths; a second common supply flow path different from the first common supply flow path; a pressure chamber for changing a cross-sectional area of ​​a flow path through which liquid flows, the pressure chamber being provided between the pressure chamber and the second common supply flow path; and a second adjustment unit that adjusts the liquid ejection head according to claim 1 . 。

11. 11. The coloring material contained in the liquid has an average particle size of 2 μm or more. Item 1. A liquid ejection head according to item 1.

12. A liquid ejection head according to any one of claims 1 to 11, a discharge control unit that controls a discharge operation for discharging liquid from the liquid discharge head; Liquid discharge device.

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