Liquid ejection head and liquid ejection device

Abstract

To solve the problem that resistance of wiring connected to a common electrode is large.SOLUTION: A liquid discharge head includes: a nozzle substrate provided with a first nozzle and a second nozzle; a pressure chamber substrate provided with a first pressure chamber and a second pressure chamber; a first piezoelectric element for imparting a pressure to liquid in the first pressure chamber; a second piezoelectric element for imparting a pressure to liquid in the second pressure chamber; a sealing substrate provided so as to cover the first piezoelectric element and the second piezoelectric element; a wiring board for applying a voltage to a common electrode, a first individual electrode and a second individual electrode; a first wiring part which is provided on an upper part of the pressure chamber substrate and electrically connects the common electrode and the wiring board; a second wiring part which is provided on a lower surface of the sealing substrate and electrically connects the common electrode and the wiring board; and a third wiring part which is provided between the first piezoelectric element and the second piezoelectric element, and electrically connects the first wiring part and the second wiring part.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] The liquid ejection head described in Patent Document 1 below includes nozzles for ejecting liquid, pressure chambers communicating with the nozzles, and piezoelectric elements for applying pressure fluctuations to the liquid in the pressure chambers. The piezoelectric elements include individual electrodes provided for each of the pressure chambers, a common electrode provided in common to the individual electrodes, and a piezoelectric body disposed between the individual electrodes and the common electrode. The liquid ejection head also includes a wiring substrate for supplying voltage to the individual electrodes and the common electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-3827 Summary of the Invention [Problem to be solved by the invention]

[0004] The liquid ejection head has wiring that electrically connects the common electrode and the wiring substrate. In liquid ejection heads according to conventional technology, the wiring that electrically connects the common electrode and the wiring substrate is provided on a pressure chamber substrate in which pressure chambers are formed. In liquid ejection heads according to conventional technology, there is a problem in that the resistance of the wiring connected to the common electrode is high. [Means for solving the problem]

[0005] The present invention is a liquid ejection head, comprising: a nozzle substrate provided with a first nozzle for ejecting liquid and a second nozzle provided adjacent to the first nozzle for ejecting liquid; a pressure chamber substrate provided above the nozzle substrate with a first pressure chamber communicating with the first nozzle and a second pressure chamber communicating with the second nozzle; a first piezoelectric element comprising a common electrode, a first piezoelectric body, and a first individual electrode, which applies pressure to the liquid in the first pressure chamber; and a second piezoelectric element comprising a common electrode, a second piezoelectric body, and a second individual electrode, which applies pressure to the liquid in the second pressure chamber. a sealing substrate provided on the upper part of the pressure chamber substrate so as to cover the first piezoelectric element and the second piezoelectric element; a wiring substrate for applying voltage to the common electrode, the first individual electrode, and the second individual electrode; a first wiring portion provided on the upper part of the pressure chamber substrate and electrically connecting the common electrode and the wiring substrate; a second wiring portion provided on the lower surface of the sealing substrate and electrically connecting the common electrode and the wiring substrate; and a third wiring portion provided between the first piezoelectric element and the second piezoelectric element and electrically connecting the first wiring portion and the second wiring portion.

[0006] The liquid ejection device of the present invention includes a liquid ejection head and a control unit that controls the ejection operation from the liquid ejection head. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an exploded perspective view showing a liquid ejection head according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a plan view showing individual electrodes, common electrodes, COM wiring, and VBS wiring arranged on a pressure chamber substrate. [Figure 4] FIG. 2 is a cross-sectional view showing a cross section along the YZ plane of the liquid ejection head. [Figure 5] FIG. 2 is an enlarged cross-sectional view showing a cross section along the YZ plane of the liquid ejection head. [Figure 6] FIG. 2 is an enlarged cross-sectional view showing a piezoelectric element, a COM wiring, and a VBS wiring. [Figure 7] 10 is a cross-sectional view showing a VBS wiring and a wiring portion provided on the lower surface of a sealing plate. FIG. [Figure 8] FIG. 10 is a cross-sectional view showing a liquid ejection head according to a second embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing a liquid ejection head according to a third embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a liquid ejection head according to a fourth embodiment. [Figure 11] FIG. 10 is a cross-sectional view showing a liquid ejection head according to a fifth embodiment. [Figure 12] FIG. 13 is a plan view showing a part of a pressure chamber substrate of a liquid ejection head according to a sixth embodiment. [Figure 13] 1 is a schematic diagram illustrating a liquid ejection device according to an embodiment. [Figure 14] 1 is a block diagram illustrating a liquid ejection device according to an embodiment.

[0008] Hereinafter, embodiments of 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 those of the actual parts. Furthermore, since the embodiments described below are preferred specific examples of the present invention, various technically preferable limitations are applied, 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 intersecting directions may be referred to 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 X-axis direction, the Y-axis direction, and the Z-axis direction are perpendicular to each other. Furthermore, the "Z1 direction" may be referred to as the "lower side" or "bottom," and the "Z2 direction" may be referred to as the "upper side" or "top."

[0010] Example 1 A liquid ejection head 10 according to a first embodiment will be described with reference to Figures 1 to 7. Figure 1 is an exploded perspective view showing the liquid ejection head 10 according to the first embodiment. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a plan view showing the individual electrodes 51, common electrodes 52, COM wiring 54, and VBS wiring 55 arranged on a pressure chamber substrate 25. The liquid ejection head 10 employs a circulation system that circulates liquid that has flowed through the common liquid chambers RA, RB and pressure chambers CA, CB.

[0011] As shown in FIG. 1, the liquid ejection head 10 includes a pressure chamber array CAL and a pressure chamber array CBL. The pressure chamber array CAL includes a plurality of pressure chambers CA aligned in the Y-axis direction. The pressure chamber array CBL includes a plurality of pressure chambers CB aligned in the Y-axis direction. The pressure chamber array CAL and the pressure chamber array CBL are spaced apart from each other in the X-axis direction. When there is no need to distinguish between the "pressure chambers CA" and the "pressure chambers CB," they may be referred to as "pressure chambers C." When there is no need to distinguish between the "pressure chamber array CAL" and the "pressure chamber array CBL," they may be referred to as "pressure chamber array CL." The pressure chamber array CL includes a plurality of pressure chambers C aligned in the Y-axis direction.

[0012] As shown in Figures 1 and 2, the liquid ejection head 10 includes a nozzle substrate 21, a compliance substrate 23, a communication plate 24, a pressure chamber substrate 25, a vibration plate 26, a sealing plate 27, and piezoelectric elements 50A and 50B. The liquid ejection head 10 also includes a case 28 and a COF 60. COF is an abbreviation for Chip on Film. In this embodiment, a liquid ejection head 10 that ejects ink, which is an example of a liquid, will be described. The liquid is not limited to ink, and the liquid ejection head 10 can eject other liquids. When there is no need to distinguish between the "piezoelectric element 50A" and the "piezoelectric element 50B," they may be referred to as the "piezoelectric element 50."

[0013] The thickness directions of the nozzle substrate 21, compliance substrate 23, communication plate 24, pressure chamber substrate 25, vibration plate 26, sealing plate 27, and case 28 are aligned along the Z-axis direction. The nozzle substrate 21 and compliance substrate 23 are disposed at the bottom of the liquid ejection head 10. The communication plate 24 is disposed in the Z2 direction from the nozzle substrate 21 and compliance substrate 23. The pressure chamber substrate 25 is disposed in the Z2 direction from the communication plate 24. The vibration plate 26 is disposed in the Z2 direction from the pressure chamber substrate 25. A plurality of piezoelectric elements 50A and 50B are formed on the vibration plate 26. A sealing plate 27 is disposed in the Z2 direction from the vibration plate 26. The sealing plate 27 covers the plurality of piezoelectric elements 50. The case 28 is disposed on the communication plate 24. The piezoelectric element 50A is provided corresponding to the pressure chamber CA. The piezoelectric element 50B is provided corresponding to the pressure chamber CB. 2 does not show wiring portions 72 and 73, which will be described later. The wiring portions 72 and 73 are shown in FIGS.

[0014] Next, the flow path 40 through which ink flows will be described. The flow path 40 through which ink flows is formed in the liquid ejection head 10. The flow path 40 includes a supply port 42A, an outlet 42B, common liquid chambers RA and RB, relay flow paths 43A and 43B, pressure chambers CA and CB, communication flow paths 45A to 45C, and a nozzle N.

[0015] The flow path 40 includes a plurality of individual flow paths 41. The plurality of individual flow paths 41 are provided corresponding to the plurality of nozzles N, respectively. The individual flow paths 41 have an individual flow path 41A and an individual flow path 41B. The individual flow path 41A includes a relay flow path 43A, a pressure chamber CA, a communicating flow path 45A, and a part of the communicating flow path 45C. The common liquid chamber RA is commonly connected to the plurality of individual flow paths 41A and supplies ink to the plurality of individual flow paths 41A. The individual flow path 41A is a portion of the individual flow path 41 that is upstream of the nozzle N.

[0016] The individual flow paths 41B include relay flow paths 43B, pressure chambers CB, communication flow paths 45B, and parts of the communication flow paths 45C. The common liquid chamber RB is commonly connected to the individual flow paths 41B. Ink is discharged from the individual flow paths 41B into the common liquid chamber RB. The common liquid chamber RB discharges ink from the individual flow paths 41B.

[0017] The liquid ejection head 10 employs a circulation system in which ink that has flowed through the pressure chambers CA and CB is circulated. As shown in FIG. 13, a circulation mechanism 8 that circulates the ink is connected to the liquid ejection head 10. A liquid container 2 is connected to the circulation mechanism 8. The circulation mechanism 8 includes a supply flow path 81 that supplies ink to the liquid ejection head 10, a recovery flow path 82 that recovers ink discharged from the liquid ejection head 10, and a pump 83 that transports the ink. The supply flow path 81 and the recovery flow path 82 may be flow paths within tubes, for example. The supply flow path 81 and the recovery flow path 82 include flow paths formed by openings, grooves, recesses, etc.

[0018] The ink in the liquid container 2 is transported by the pump 83, flows through the supply flow path 81, passes through the supply port 42A, and flows into the common liquid chamber RA. A portion of the common liquid chamber RA is formed in the communication plate 24, and a portion of the common liquid chamber RA is formed in the case 28. The ink in the common liquid chamber RA passes through the relay flow path 43A and is supplied to the pressure chamber CA. The ink in the pressure chamber CA passes through the communication flow path 45A and the communication flow path 45C, and is ejected from the nozzle N.

[0019] Ink that is not ejected from the nozzle N flows through the communication flow path 45C and the communication flow path 45B and into the pressure chamber CB. The ink in the pressure chamber CB passes through the relay flow path 43B and is discharged into the common liquid chamber RB. The ink in the common liquid chamber RB flows into the recovery flow path 82 through the discharge port 42B and is recovered in the liquid container 2. In this manner, ink is circulated in the liquid ejection head 10.

[0020] Next, the structure of the liquid ejection head 10 will be described. A plurality of nozzles N are formed on the nozzle substrate 21 shown in Figures 1 and 2. The plurality of nozzles N constitute a nozzle row NL. The nozzle row NL includes a plurality of nozzles N lined up in the Y-axis direction. The nozzles N are through-holes that penetrate the nozzle substrate 21 in the Z-axis direction.

[0021] The compliance substrates 23 are disposed on both sides of the nozzle substrate 21 in the X-axis direction. The compliance substrates 23 include flexible films. The compliance substrates 23 form the bottom surfaces of the common liquid chambers RA and RB. The compliance substrates 23 are deformable when subjected to ink pressure. The compliance substrates 23 deform due to ink pressure, and can absorb pressure fluctuations of the ink inside the liquid ejection head 10.

[0022] Parts of the common liquid chambers RA and RB, relay flow paths 43A and 43B, and communicating flow paths 45A to 45C are formed in the communicating plate 24. Through holes, grooves, recesses, etc. are formed in the communicating plate 24. Parts of the common liquid chambers RA and RB, relay flow paths 43, and communicating flow paths 45 are formed by these through holes, grooves, recesses, etc.

[0023] The common liquid chambers RA, RB are elongated in the Y-axis direction. The common liquid chambers RA, RB correspond to the arrangement of the multiple nozzles N in the Y-axis direction. As shown in FIG. 2, the upper portions of the common liquid chambers RA, RB are formed in the case 28, and the lower portions of the common liquid chambers RA, RB are formed in the communication plate 24. The lower portions of the common liquid chambers RA, RB formed in the communication plate 24 penetrate in the Z-axis direction. The portion of the common liquid chamber RA closer to the nozzle N is formed up to a position overlapping with the pressure chamber CA when viewed in the Z-axis direction. Similarly, the portion of the common liquid chamber RB closer to the nozzle N is formed up to a position overlapping with the pressure chamber CB when viewed in the Z-axis direction.

[0024] The relay flow path 43A communicates between the pressure chamber CA and the common liquid chamber RA. A relay flow path 43A is provided for each of the multiple pressure chambers CA. The multiple relay flow paths 43A are arranged at predetermined intervals in the Y-axis direction. The relay flow path 43B communicates between the pressure chamber CB and the common liquid chamber RB. A relay flow path 43B is provided for each of the multiple pressure chambers CB. The multiple relay flow paths 43B are arranged at predetermined intervals in the Y-axis direction.

[0025] The communication flow passages 45A communicate with the pressure chambers CA and extend in the Z-axis direction. The communication flow passages 45A are provided for each of the pressure chambers CA. The communication flow passages 45B communicate with the pressure chambers CB and extend in the Z-axis direction. The communication flow passages 45B are provided for each of the pressure chambers CB.

[0026] The communicating channels 45A and 45B penetrate the communicating plate 24 in the Z-axis direction. The communicating channels 45A and 45B are spaced apart from each other in the X-axis direction. The communicating channel 45A is disposed at a position overlapping with the pressure chamber CA when viewed in the Z-axis direction. The communicating channel 45B is disposed at a position overlapping with the pressure chamber CB when viewed in the Z-axis direction. The communicating channel 45C extends in the X-axis direction and communicates the communicating channel 45A with the communicating channel 45B. The communicating channel 45C is a groove recessed from the bottom surface of the communicating plate 24. The communicating channel 45C communicates with the nozzle N. The multiple communicating channels 45A to 45C are disposed at predetermined intervals in the Y-axis direction. The nozzle substrate 21 is disposed so as to cover the communicating channels 45A to 45C from below. The pressure chambers CA and CB are communicated with each other by the communicating channels 45A to 45C.

[0027] A plurality of pressure chambers CA, CB are formed in the pressure chamber substrate 25. The pressure chambers CA, CB penetrate the pressure chamber substrate 25 in the Z-axis direction. The pressure chambers CA, CB have a predetermined volume. The pressure chambers CA, CB are spaced apart from each other in the X-axis direction. A plurality of pressure chambers CA are provided corresponding to each of the plurality of nozzles N. The plurality of pressure chambers CA are arranged at predetermined intervals in the Y-axis direction. A plurality of pressure chambers CB are provided corresponding to each of the plurality of nozzles N. The plurality of pressure chambers CB are arranged at predetermined intervals in the Y-axis direction. As described above, the pressure chamber array CAL includes a plurality of pressure chambers CA. The pressure chamber substrate 25 can be manufactured from a single crystal substrate of silicon, for example. The pressure chamber substrate 25 may also be manufactured from other materials.

[0028] FIG. 3 is a plan view showing the individual electrodes 51, common electrodes 52, COM wiring 54, and VBS wiring 55 arranged on the pressure chamber substrate 25. FIG. 4 is a cross-sectional view showing a cross section along the YZ plane of the liquid ejection head 10. FIG. 5 is a cross-sectional view showing an enlarged cross section along the YZ plane of the liquid ejection head 10. The YZ plane is a plane along the Y-axis direction and the Z-axis direction, and is a plane that intersects with the X-axis direction. FIG. 4 shows a plurality of pressure chambers C lined up in the Y-axis direction, and FIG. 5 shows an enlarged view of one pressure chamber C. FIG. 6 shows the piezoelectric element 50,

[0029] The diaphragm 26 is disposed on the upper surface of the pressure chamber substrate 25. The diaphragm 26 covers the opening of the pressure chamber substrate 25. The portion of the diaphragm 26 that covers the opening of the pressure chamber substrate 25 forms the upper wall surface of the pressure chamber C.

[0030] The diaphragm 26 includes an elastic layer 26a and an insulating layer 26b. The elastic layer 26a is made of, for example, silicon dioxide (SiO2). The insulating layer 26b is made of, for example, zirconium dioxide (ZrO2). The elastic layer 26a is formed on the pressure chamber substrate 25, and the insulating layer 26b is formed on the elastic layer 26a.

[0031] A plurality of piezoelectric elements 50A, 50B are formed on the vibration plate 26. The piezoelectric element 50A shown in FIGS. 1 and 2 is disposed at a position overlapping with the pressure chamber CA when viewed in the Z-axis direction. The piezoelectric element 50B is disposed at a position overlapping with the pressure chamber CB when viewed in the Z-axis direction. The piezoelectric element 50A is provided for each of the plurality of pressure chambers CA. The piezoelectric element 50B is provided for each of the plurality of pressure chambers CB.

[0032] The diaphragm 26 is driven by piezoelectric elements 50A and 50B and vibrates in the Z-axis direction. The diaphragm 26, which forms the upper wall surface of the pressure chamber CA, is driven by the piezoelectric element 50A above the pressure chamber CA. The diaphragm 26, which forms the upper wall surface of the pressure chamber CB, is driven by the piezoelectric element 50 above the pressure chamber CA. 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, if the total thickness of the diaphragm 26 is 15 μm or less, it may include a resin layer. The diaphragm 26 may be made of metal. Examples of metals include stainless steel and nickel. If the diaphragm 26 is made of metal, the thickness of the diaphragm 26 may be 15 μm or more and 100 μm or less.

[0033] As shown in Figures 3 to 5, the multiple pressure chambers C include pressure chambers C1 and C2 that are aligned in the Y-axis direction. "Pressure chamber C1" is an example of a "first pressure chamber." "Pressure chamber C2" is an example of a "second pressure chamber." Pressure chamber C1 and pressure chamber C2 have the same structure but differ in their positions in the Y-axis direction. Of two pressure chambers C adjacent to each other in the Y-axis direction, one will be referred to as "pressure chamber C1" and the other as "pressure chamber C2." Pressure chambers C1 and C2 are arranged alternately in the Y-axis direction.

[0034] As shown in Figures 1 and 4, the multiple nozzles N include nozzle N1 and nozzle N2 aligned in the Y-axis direction. "Nozzle N1" is an example of a "first nozzle." "Nozzle N2" is an example of a "second nozzle." Nozzle N1 and nozzle N2 have the same structure, but differ in their positions in the Y-axis direction. As shown in Figure 4, pressure chamber C1 communicates with nozzle N1. Pressure chamber C2 communicates with nozzle N2.

[0035] As shown in FIGS. 4 and 5, the piezoelectric element 50 includes an individual electrode 51, a common electrode 52, and a piezoelectric body 53. The plurality of piezoelectric elements 50 includes a piezoelectric element 501 and a piezoelectric element 502. The "piezoelectric element 501" is an example of a "first piezoelectric element." The "piezoelectric element 502" is an example of a "second piezoelectric element." The piezoelectric element 501 applies pressure to the liquid in the pressure chamber C1. The piezoelectric element 502 applies pressure to the liquid in the pressure chamber C2.

[0036] The piezoelectric element 501 has an individual electrode 511, a common electrode 521, and a piezoelectric body 531. The piezoelectric element 502 has an individual electrode 512, a common electrode 522, and a piezoelectric body 532. The piezoelectric elements 501 and 502 have the same configuration. When there is no need to distinguish between the "piezoelectric element 501" and the "piezoelectric element 502," they may be referred to as "piezoelectric element 50." Similarly, when there is no need to distinguish between the "individual electrode 511" and the "individual electrode 512," they may be referred to as "individual electrode 51." The "individual electrode 511" is an example of a "first individual electrode." The "individual electrode 512" is an example of a "second individual electrode."

[0037] When there is no need to distinguish between the "common electrode 521" and the "common electrode 522," they may be referred to as the "common electrode 52." The common electrode 521 includes a portion disposed above the individual electrode 511. The common electrode 522 includes a portion disposed above the individual electrode 512. When there is no need to distinguish between the "piezoelectric body 531" and the "piezoelectric body 532," they may be referred to as the "piezoelectric body 53." The "piezoelectric body 531" is an example of a "first piezoelectric body." The "piezoelectric body 532" is an example of a "second piezoelectric body."

[0038] The individual electrode 51, the piezoelectric body 53, and the common electrode 52 are layered in this order on the vibration plate 26. The individual electrode 511, the piezoelectric body 531, and the common electrode 521 are located above the pressure chamber C1. The individual electrode 512, the piezoelectric body 532, and the common electrode 522 are located above the pressure chamber C2. The piezoelectric body 53 is sandwiched between the individual electrode 51 and the common electrode 52. The piezoelectric body 531 is sandwiched between the individual electrode 511 and the common electrode 521. The piezoelectric body 532 is sandwiched between the individual electrode 512 and the common electrode 522.

[0039] As shown in FIG. 3, the individual electrode 51 has an elongated shape extending along the X-axis direction. The multiple individual electrodes 51 are arranged at intervals from one another in the Y-axis direction. The multiple individual electrodes 51 are arranged for each of the multiple pressure chambers C. As shown in FIG. 4, an individual electrode 511 is provided for the pressure chamber C1. An individual electrode 512 is provided for the pressure chamber C2. The individual electrode 511 is arranged at a position overlapping the pressure chamber C1 when viewed in the Z-axis direction. The individual electrode 512 is arranged at a position overlapping the pressure chamber C2 when viewed in the Z-axis direction.

[0040] The common electrode 52 is strip-shaped and extends in the Y-axis direction. The common electrode 52 is continuous so as to cover the plurality of individual electrodes 511 and 512. Of the common electrode 52 extending in the Y-axis direction, the portion located above the individual electrode 511 may be referred to as common electrode 521, and the portion located above the individual electrode 512 may be referred to as common electrode 522.

[0041] The individual electrodes 51 include a base layer and an electrode layer. The base layer 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 elements 53A and 53B are formed of a known piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3) or ceramic.

[0042] The common 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 or lanthanum nickelate. The region of the piezoelectric body 53 between the individual electrode 51 and the common electrode 52 is the driving region. The region of the piezoelectric body 531 between the individual electrode 511 and the common electrode 521 is the driving region. The region of the piezoelectric body 532 between the individual electrode 512 and the common electrode 522 is the driving region. The driving regions of the piezoelectric body 53 are formed above the multiple pressure chambers C, respectively. The piezoelectric bodies 531 and 532 may be connected in portions other than the driving regions.

[0043] A predetermined reference voltage is applied to the common electrode 52. The reference voltage is a constant voltage, and is set to, for example, a voltage higher than the ground voltage. For example, a hold signal having a constant voltage is applied to the common electrode 52. A drive signal having a varying voltage is applied to the individual electrode 51. A voltage corresponding to the difference between the reference voltage applied to the common electrode 52 and the drive signal supplied to the individual electrode 51 is applied to the piezoelectric element 53. A voltage corresponding to the difference between the reference voltage applied to the common electrode 521 and the drive signal supplied to the individual electrode 511 is applied to the piezoelectric element 531. A voltage corresponding to the difference between the reference voltage applied to the common electrode 522 and the drive signal supplied to the individual electrode 512 is applied to the piezoelectric element 532. The drive signal corresponds to the amount of liquid ejected from the nozzle N.

[0044] When a voltage is applied between the individual electrode 51 and the common electrode 521, the piezoelectric body 531 is deformed, and the piezoelectric element 501 generates energy that flexes and deforms the diaphragm 26. Similarly, when a voltage is applied between the individual electrode 512 and the common electrode 522, the piezoelectric body 532 is deformed, and the piezoelectric element 502 generates energy that flexes and deforms the diaphragm 26.

[0045] The vibration plate 26 vibrates due to the energy generated by the piezoelectric element 501, which changes the pressure of the liquid in the pressure chamber C1, causing the liquid in the pressure chamber C1 to be ejected from the nozzle N1. The vibration plate 26 vibrates due to the energy generated by the piezoelectric element 502, which changes the pressure of the liquid in the pressure chamber C2, causing the liquid in the pressure chamber C2 to be ejected from the nozzle N2.

[0046] The sealing plate 27 has a rectangular shape when viewed in the Z-axis direction. The sealing plate 27 protects the multiple piezoelectric elements 50 and reinforces the mechanical strength of the pressure chamber substrate 25 and the vibration plate 26. The sealing plate 27 is adhered to the vibration plate 26 by, for example, an adhesive. The sealing plate 27 is fixed to the pressure chamber substrate 25 via the vibration plate 26. Wiring portions 72 are formed on the lower surfaces 27c, 27d, and 27e of the sealing plate 27. This will be described in more detail below.

[0047] 1 and 2, the COF 60 includes a flexible wiring board 61 and a drive circuit 62. The flexible wiring board 61 is a flexible wiring board. The flexible wiring board 61 is, for example, an FPC. The flexible wiring board 61 may also be, for example, an FFC. FPC is an abbreviation for Flexible Printed Circuit. FFC is an abbreviation for Flexible Flat Cable.

[0048] 2, the flexible wiring board 61 is electrically connected to the individual electrodes 51 of the piezoelectric elements 50 via COM wiring 54A and 54B, which will be described later. The flexible wiring board 61 is also electrically connected to the common electrode 52 of the piezoelectric elements 50 via a VBS wiring 55, which will be described later. The flexible wiring board 61 is electrically connected to a circuit board (not shown). The circuit board includes a drive signal generating circuit 32, which is shown in FIG.

[0049] The drive circuit 62 is mounted on the flexible wiring board 61. The drive circuit 62 includes a switching element for driving the piezoelectric element 50. The drive circuit 62 is electrically connected to the control unit 30 shown in FIG. 14 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 element 50. The drive circuit 62 supplies a drive voltage or current to the piezoelectric element 50 to vibrate the diaphragm 26.

[0050] 3 and 6, the liquid ejection head 10 includes a COM wiring 54. The COM wiring 54 is electrically connected to the piezoelectric element 50. The plurality of COM wirings 54 are connected to the plurality of individual electrodes 51, respectively.

[0051] The multiple COM wires 54 extend in the X-axis direction and are drawn out into the openings 27a of the sealing plate 27. The openings 27a are shown in FIGS. 1 and 2. Note that the COM wires 54 are not shown in FIG. 1. The openings 27a penetrate the sealing plate 27 in the Z-axis direction. As viewed in the Z-axis direction, they are electrically connected to the COF 60 at positions corresponding to the openings 27a. The COM wires 54 are formed of a conductive material with lower resistance than the individual electrodes 51. For example, the COM wires 54 are a conductive pattern having a structure in which a gold (Au) conductive film is laminated on the surface of a conductive film made of nichrome (NiCr).

[0052] As shown in FIG. 6, the COM wiring 54 has an electrode layer 54a, a first adhesion layer 54b, and a first wiring layer 54c. The electrode layer 54a covers the end face of the piezoelectric body 53 in the X2 direction. The end face in the X2 direction forms a plane that intersects with the X-axis direction. The first adhesion layer 54b covers the electrode layer 54a and the individual electrode 51. The first adhesion layer 54b is in close contact with the electrode layer 54a and the individual electrode 51. The first wiring layer 54c covers the first adhesion layer 54b. The first wiring layer 54c is electrically connected to the individual electrode 51 via the first adhesion layer 54b.

[0053] 2, the COM wiring 54 is electrically connected to the flexible wiring substrate 61 via a COF mounting portion 64. The COF mounting portion 64 includes a conductive layer that electrically connects a first wiring layer 54c of the COM wiring 54 to a wiring portion of the flexible wiring substrate 61. The individual electrodes 51 are electrically connected to the drive circuit 62 via the COM wiring 54, the COF mounting portion 64, and the flexible wiring substrate 61.

[0054] As shown in FIGS. 3 to 8, the liquid ejection head 10 includes a VBS wiring 55. The VBS wiring 55 is electrically connected to the common electrode 52. The VBS wiring 55 is electrically connected to the COF 60 via a VBS wiring mounting portion (not shown). The VBS wiring mounting portion is disposed, for example, at both ends of the liquid ejection head 10 in the Y-axis direction. The "VBS wiring 55" is an example of a "first wiring portion."

[0055] 6, the VBS wiring 55 and the COM wiring 54 are spaced apart in the X-axis direction. An insulating adhesive 59 is provided between the VBS wiring 55 and the COM wiring 54. The sealing plate 27 is adhered to the VBS wiring 55A and 55B, the piezoelectric elements 53A and 53B, the COM wiring 54, etc. using the adhesive 59.

[0056] As shown in FIG. 3, the VBS wiring 55 extends in the Y-axis direction. The VBS wiring 55 is disposed on the common electrode 52. The liquid ejection head 10 may have a plurality of VBS wirings 55 spaced apart in the X-axis direction on the common electrode 52. The VBS wiring 55 may be formed so as to cover the entire width of the common electrode 52 in the X-axis direction. The VBS wiring 55 is formed so as to overlap a plurality of pressure chambers C when viewed in the Z-axis direction. The VBS wiring 55 may be formed so as to overlap all of the pressure chambers C aligned in the Y-axis direction. The VBS wiring 55 may be formed partially in the Y-axis direction. The material of the VBS wiring 55 is, for example, gold (Au). The material of the VBS wiring 55 is not limited to gold and may be other metals.

[0057] 4 and 5, the liquid ejection head 10 includes a wiring portion 72 and a wiring portion 73. The wiring portion 72 is provided on the lower surfaces 27c, 27d, 27e, and 27f of the sealing plate 27. The wiring portion 73 is provided between the VBS wiring 55 and the wiring portion 72, and electrically connects the VBS wiring 55 and the wiring portion 72. The "wiring portion 72" is an example of a "second wiring portion," and the "wiring portion 73" is an example of a "third wiring portion."

[0058] 5, the sealing plate 27 has a top surface 27b and bottom surfaces 27c, 27d, 27e, and 27f. The top surface 27b is the upper surface. The bottom surface 27c is the lower surface located in the Z1 direction relative to the top surface 27b.

[0059] The sealing plate 27 has protruding portions 27g that protrude in the Z1 direction beyond the lower surface 27c (in other words, that protrude beyond the lower surface 27c in the Z1 direction). The protruding portions 27g protrude closer to the pressure chamber substrate 25 than the lower surface 27c. The protruding portions 27g extend in the X-axis direction. The multiple protruding portions 27g are arranged at predetermined intervals in the Y-axis direction.

[0060] The protruding portion 27g includes lower surfaces 27e, 27f, and 27d. The lower surfaces 27e and 27d form inclined surfaces of the protruding portion 27g. The lower surfaces 27e and 27d are inclined with respect to the upper surface 27c. The lower surfaces 27e and 27d are inclined with respect to the XY plane. The XY plane is a plane along the X-axis direction and the Y-axis direction. The lower surfaces 27e and 27d are inclined with respect to the upper surface 25a of the pressure chamber substrate 25. The lower surface 27e is adjacent to the lower surface 27c in the Y2 direction. The lower surface 27d is adjacent to the lower surface 27c in the Y1 direction.

[0061] Lower surface 27f forms the bottom surface of protruding portion 27g. Lower surface 27f is located between lower surface 27e and lower surface 27d in the Y-axis direction. Lower surface 27f is along the XY plane. Lower surface 27f is located at a different position from lower surface 27c in the Z-axis direction. Lower surface 27f is located between pressure chamber C1 and pressure chamber C2 in the Y-axis direction.

[0062] As described above, the wiring portion 72 is arranged along the lower surfaces 27c, 27d, 27e, and 27f of the sealing plate 27. The wiring portion 72 includes a conductive layer. The wiring portion 72 has a predetermined thickness. The wiring portion 72 is arranged so as to overlap the plurality of piezoelectric elements 50 when viewed in the Z-axis direction. The wiring portion 72 is spaced apart from the VBS wiring 55 in the Z-axis direction. The wiring portion 72 is formed so as to cover the lower surfaces 27c, 27d, 27e, and 27f from below.

[0063] The wiring portion 72 includes portions 72c, 72d, 72e, and 72f. These portions 72c, 72d, 72e, and 72f are continuous in the Y-axis direction. The portion 72c is formed so as to cover the lower surface 27c of the sealing plate 27. The portion 72d is formed so as to cover the lower surface 27d of the sealing plate 27. The portion 72d is inclined with respect to the portion 72c. The portion 72e is formed so as to cover the lower surface 27e of the sealing plate 27. The portion 72e is inclined with respect to the portion 72c. The portion 72f is formed so as to cover the lower surface 27f of the sealing plate 27. The portions 72d, 72d, and 72f are formed so as to cover the protruding portion 27g.

[0064] As described above, the wiring portion 73 electrically connects the VBS wiring 55 and the wiring portion 72. The wiring portion 73 is provided between the plurality of piezoelectric elements 50 in the Y-axis direction. The wiring portion 73 is located between the piezoelectric element 501 and the piezoelectric element 502 in the Y-axis direction. The wiring portion 73 is electrically connected to the portion 72d of the wiring portion 72. The wiring portion 73 connects the wiring portion 72 and the VBS wiring 55 in the Z-axis direction.

[0065] The pressure chamber substrate 25 has partition walls 25c that partition a plurality of pressure chambers C in the Y-axis direction. The partition walls 25c are located between the pressure chambers C1 and C2 in the Y-axis direction. The protruding portions 27g of the sealing plate 27 are arranged so as to overlap the partition walls 25c when viewed in the Z-axis direction. The lower surfaces 27d of the protruding portions 27g are arranged so as to overlap the partition walls 25c when viewed in the Z-axis direction.

[0066] The wiring portion 73 is arranged so as to overlap with the partition wall 25c when viewed in the Z-axis direction. The wiring portion 73 is arranged above the partition wall 25c. The wiring portion 73 is electrically connected to the VBS 55 at a position above the partition wall 25c.

[0067] FIG. 7 is a cross-sectional view showing the VBS wiring 55, wiring portion 72, and wiring portion 73. FIG. 7 shows a cross section along the YZ plane. The thickness t2 of the wiring portion 72 is thicker than the thickness t1 of the VBS wiring 55. The thickness t2 of the wiring portion 72 is the thickness in a direction intersecting the direction in which the wiring portion 72 extends. The thickness t2 of the wiring portion 72 may be the thickness of portion 72c, for example. The thickness of portion 72c is along the Z-axis direction. The thickness t1 of the VBS wiring 55 may be the thickness along the Z-axis direction. The thickness t2 of the wiring portion 72 may be the average thickness over the entire length of the wiring portion 72. The thickness t1 of the VBS wiring 55 may be the average thickness over the entire length of the VBS wiring 55. The thickness t1 of the VBS wiring 55 may be the thickness at a position above the piezoelectric element 50. By making the thickness t2 of the wiring portion 72 thicker than the thickness t1 of the VBS wiring 55, lower resistance can be achieved. Because the VBS wiring 55 is provided on the piezoelectric element 50, increasing the thickness t1 of the VBS wiring 55 to lower its resistance may affect the ease with which the piezoelectric element 50 deforms, potentially affecting the liquid ejection performance. Increasing the thickness t2 of the wiring portion 72 makes it possible to lower its resistance without affecting the liquid ejection performance of the piezoelectric element 50. Furthermore, increasing the thickness t2 of the wiring portion 72 that contacts the sealing plate 27 increases the rigidity of the sealing plate 27, making it possible to suppress deformation of the pressure chamber substrate 25. This reduces structural crosstalk.

[0068] The thickness t3 of the wiring portion 73 is thicker than the thickness t1 of the VBS wiring 55. The thickness t3 of the wiring portion 73 is thicker than the thickness t2 of the wiring portion 72. The thickness t3 of the wiring portion 73 is along the Z-axis direction. The thickness t3 of the wiring portion 73 may be the thickness obtained by subtracting the thickness t1 from the thickness t4. The thickness t4 corresponds to the length in the Z-axis direction between the lower surface 27f of the protruding portion 27g and the VBS wiring 55. The thickness t4 is thicker than the thickness t1.

[0069] The width W2 of the wiring portion 73 is shorter than the width W1 of the partition wall 25c between the pressure chambers C. The width W3 of the wiring portion 73 is the length along the Y-axis direction. The partition wall 25c is the length along the Y-axis direction. The wiring portion 73 is disposed within the width W1 of the partition wall 25c when viewed from the Z-axis direction. The width W2 of the wiring portion 73 may be, for example, approximately the same as the width along the Y-axis direction of the lower surface 27f of the protrusion portion 27g.

[0070] The wiring portion 72 and the wiring portion 73 are, for example, made of the same material. The wiring portion 72 and the wiring portion 73 are, for example, made of gold. The VBS wiring 55 and the wiring portions 72 and 73 are, for example, made of the same material, that is, gold. The VBS wiring 55 and the wiring portions 72 and 73 may be made of a metal other than gold. The VBS wiring 55 and the wiring portions 72 and 73 do not have to be made of the same material. If the VBS wiring 55 and the wiring portions 72 and 73 are made of the same material, the bonding quality is improved. The bonding portion between the VBS wiring 55 and the wiring portion 73 is positioned so as to overlap with the partition wall 25c when viewed in the Z-axis direction.

[0071] According to this liquid ejection head 10, a voltage can be supplied to the common electrode 52 via the VBS wiring 55. The liquid ejection head 10 includes wiring portions 72 and 73 that are electrically connected to the VBS wiring 55, and therefore a voltage can be supplied to the common electrode 52 via the wiring portions 72 and 73. The liquid ejection head 10 can supply a voltage to the common electrode 52 via the COF 60, the wiring portions 72 and 73, and the VBS wiring 55. The liquid ejection head 10 can supply a voltage to the common electrode 52 using the wiring portions 72 and 73 in addition to the VBS wiring 55. This reduces the resistance of the wiring connected to the common electrode 52. The liquid ejection head 10 can suppress the effect of a voltage drop supplied to the common electrode 52. The liquid ejection head 10 suppresses current delay to the common electrode 52.

[0072] The liquid ejection head 10 has the wiring portion 72 and the wiring portion 73, and therefore it is possible to reduce the resistance of the VBS wiring 55 while avoiding an increase in the thickness t1 of the VBS wiring 55. For example, in the prior art, it was difficult to further increase the thickness t1 of the VBS wiring 55. If the VBS wiring 55 was made too thick, it was difficult to cut the VBS wiring 55 with precision. Therefore, it was not easy to increase the thickness of the VBS wiring 55 and reduce its electrical resistance. In the liquid ejection head 10, the wiring portion 72 and the wiring portion 73 are formed along the lower surface of the sealing plate 27, and therefore it is possible to reduce the resistance of the VBS wiring 55 while avoiding an increase in the thickness of the VBS wiring 55.

[0073] In the liquid ejection head 10, as shown in FIG. 6, the sealing plate 27 is fixed to the pressure chamber substrate 25 and the vibration plate 26 using an adhesive 59. For example, in the prior art, if a large amount of adhesive 59 is used to adhere the sealing plate 27, there is a risk that the adhesive will overflow from the desired position. For example, if there is too much adhesive, there is a risk that the adhesive will overflow into the opening 27a of the sealing plate 27 or into the sealed space of the sealing plate 27. Furthermore, if there is too much adhesive, there is a risk that the adhesive that has soaked into the vibration plate 26 will leak into the pressure chamber C.

[0074] As shown in FIG. 5 , the liquid ejection head 10 has a protruding portion 27g that protrudes closer to the pressure chamber substrate 25 than the lower surface 27c of the sealing plate 27. Therefore, the diaphragm 26 can be pressed against the partition wall 25c of the pressure chamber substrate 25 using the protruding portion 27g and the wiring portion 73 provided on the lower surface of the protruding portion 27g. This allows the pressure chamber substrate 25, the diaphragm 26, and the sealing plate 27 to be bonded together without increasing the amount of adhesive 59 used to bond the sealing plate 27. The liquid ejection head 10 improves bonding quality while maintaining an appropriate amount of adhesive 59 used. The liquid ejection head 10 reduces the risk of the adhesive 59 leaking to the surrounding area. For example, the liquid ejection head 10 prevents the adhesive 59 from leaking into the opening 27a of the sealing plate 27, the adhesive 59 from leaking into the sealed space, and the adhesive 59 from leaking into the pressure chamber C.

[0075] In the liquid ejection head 10, the amount of adhesive 59 used is maintained at an appropriate level, thereby reducing the amount of adhesive seeping into the diaphragm 26. For example, when the amount of adhesive seeping into the diaphragm 26 above the pressure chamber C increases, vibration of the diaphragm 26 is suppressed. In the liquid ejection head 10, the amount of adhesive seeping into the diaphragm 26 is reduced, so vibration by the diaphragm 26 is not hindered. This improves the reliability of the liquid ejection performance of the liquid ejection head 10.

[0076] In the liquid ejection head 10, the protruding portions 27g and wiring portions 73 of the sealing plate 27 are disposed on the partition walls 25c between the pressure chambers C. The protruding portions 27g and wiring portions 73 are able to press down on the partition walls 25c and the vibration plate 26 on the partition walls 25c. This suppresses deflection of the partition walls 25c. If the deflection of the partition walls 25c becomes too large, it may affect the ejection performance of the liquid ejected from the pressure chambers C. In the liquid ejection head 10, the deflection of the partition walls 25c is suppressed, thereby improving the precision of the liquid ejection performance.

[0077] <Example 2> Next, a liquid ejection head 10B according to Example 2 will be described. FIG. 8 is a cross-sectional view showing a liquid ejection head according to Example 2. Example 2 has the same structure as Example 1. FIG. 8 shows three pressure chambers C1 to C3 aligned in the Y-axis direction. In Example 2, the liquid ejection head 10 will be described using the pressure chambers C1 to C3 as an example. Note that in the description of the liquid ejection head 10B, descriptions that are the same as those for the liquid ejection head 10 of Example 1 may be omitted.

[0078] The liquid ejection head 10B is equipped with a plurality of pressure chambers C. The plurality of pressure chambers C include pressure chambers C1 to C3. The pressure chambers C1 to C3 are arranged at predetermined intervals in the Y-axis direction. The pressure chambers C1 to C3 are arranged in this order. In the Y-axis direction, the pressure chamber C2 is located between the pressure chambers C1 and C3. The "pressure chamber C3" is an example of a "third pressure chamber."

[0079] A plurality of nozzles N are formed in the pressure chamber substrate 25 and aligned in the Y-axis direction. The plurality of nozzles N include nozzles N1 to N3. A nozzle row NL includes nozzles N1 to N3. The nozzles N1 to N3 are aligned in this order. In the Y-axis direction, nozzle N2 is positioned between nozzle N1 and nozzle N3. "Nozzle N3" is an example of a "third nozzle." Nozzle N3 communicates with pressure chamber C3. Liquid in pressure chamber C3 is ejected from nozzle N3.

[0080] The liquid ejection head 10 includes a plurality of piezoelectric elements 50 arranged in the Y-axis direction. The plurality of piezoelectric elements 50 includes piezoelectric element 501, piezoelectric element 502, and piezoelectric element 503. The piezoelectric elements 501 to 503 are arranged in this order. In the Y-axis direction, the piezoelectric element 502 is located between the piezoelectric elements 501 and 503. The "piezoelectric element 503" is an example of a "third piezoelectric element."

[0081] The piezoelectric element 50 includes an individual electrode 51, a common electrode 52, and a piezoelectric body 53. The piezoelectric element 503 includes an individual electrode 51, a common electrode 52, and a piezoelectric body 53. The piezoelectric element 503 is disposed at a position overlapping with the pressure chamber C3 when viewed in the Z-axis direction. The individual electrode 51 of the piezoelectric element 503 is an example of a "third individual electrode." The piezoelectric body 53 of the piezoelectric element 503 is an example of a "third piezoelectric body."

[0082] The wiring portion 73 electrically connects the wiring portion 72 and the VBS wiring 55. The wiring portion 73 is provided between the plurality of piezoelectric elements 50. The wiring portion 73 is disposed between the piezoelectric element 501 and the piezoelectric element 502. The wiring portion 73 is disposed between the piezoelectric element 502 and the piezoelectric element 503. The wiring portion 73 located between the piezoelectric element 502 and the piezoelectric element 503 is an example of a "fourth wiring portion." The wiring portion 73 may be provided between all of the plurality of piezoelectric elements 50.

[0083] Such a liquid ejection head 10B according to Example 2 may also be used. In the liquid ejection head 10B including the plurality of piezoelectric elements 501 to 503, a wiring portion 73 may be provided between the piezoelectric element 501 and the piezoelectric element 502, and a wiring portion 73 may be provided between the piezoelectric element 502 and the piezoelectric element 503. Such a liquid ejection head 10B according to Example 2 also achieves the same effects as the liquid ejection head 10 according to Example 1 described above.

[0084] Example 3 Next, a liquid ejection head 10C according to Example 3 will be described. Fig. 9 is a cross-sectional view showing the liquid ejection head 10C according to Example 3. The liquid ejection head 10C of Example 3 differs from the liquid ejection head 10B of Example 2 shown in Fig. 8 in that the protruding portion 27g of the sealing plate 27 is not formed between the piezoelectric element 502 and the piezoelectric element 503, and that the wiring portion 73 is not provided between the piezoelectric element 502 and the piezoelectric element 503. In the description of the liquid ejection head 10C of Example 3, the same description as for the liquid ejection heads 10 and 10B of Examples 1 and 2 will be omitted.

[0085] In this way, the wiring portion 73 does not have to be provided on both sides of the piezoelectric element 50. In the Y-axis direction, the wiring portion 73 may be provided on one side of the piezoelectric element 50. In the liquid ejection head 10C, the wiring portion 73 is provided between the piezoelectric element 501 and the piezoelectric element 502, and the wiring portion 73 is not provided between the piezoelectric element 502 and the piezoelectric element 503.

[0086] Similarly, in the liquid ejection head 10C, a protruding portion 27g is provided between the piezoelectric element 501 and the piezoelectric element 502, and no protruding portion 27g is provided between the piezoelectric element 502 and the piezoelectric element 503.

[0087] Example 4 Next, a liquid ejection head 10D according to Example 4 will be described. Fig. 10 is a cross-sectional view showing the liquid ejection head 10D according to Example 4. The liquid ejection head 10D of Example 4 differs from the liquid ejection head 10 of Example 1 shown in Fig. 5 in that the length of the protruding portion 27g of the sealing plate 27 in the Z-axis direction is different, and that the liquid ejection head 10D includes a wiring portion 73D instead of the wiring portion 73. Note that in the description of the liquid ejection head 10D, descriptions that are the same as those for the liquid ejection head 10 will be omitted.

[0088] 5 is located above the VBS wiring 55 on the individual electrode 51. In the liquid ejection head 10D shown in Fig. 10, the lower surface 27f of the extension portion 27g is located below the VBS wiring 55 on the individual electrode 51. In the liquid ejection head 10D, the distance between the upper surface 25a of the pressure chamber substrate 25 and the lower surface 27f of the extension portion 27g is shorter than the distance between the upper surface 25a of the pressure chamber substrate 25 of the liquid ejection head 10 and the lower surface 27f of the extension portion 27g.

[0089] In the Z-axis direction, the length of the wiring portion 73D of the liquid ejection head 10D is shorter than the length of the wiring portion 73 of the liquid ejection head 10.

[0090] In this way, in the liquid ejection head 10D, the protruding portion 27g of the sealing plate 27 is disposed at a position closer to the upper surface 25a of the pressure chamber substrate 25. This allows the length of the wiring portion 73D in the Z axis direction to be shortened.

[0091] <Example 5> Next, a liquid ejection head 10E according to Example 5 will be described. Fig. 11 is a cross-sectional view showing the liquid ejection head 10E according to Example 5. The liquid ejection head 10E according to Example 5 differs from the liquid ejection head 10B of Example 2 shown in Fig. 8 in that the sealing plate 27 does not have a protruding portion 27g, the piezoelectric body 53 is formed so as to be continuous in the Y-axis direction, the position of the common electrode 52 in the Z-axis direction is constant, the position of the VBS wiring 55 in the Z-axis direction is constant, the position of the wiring portion 72E in the Z-axis direction is constant, and wiring portion 73E is provided instead of wiring portion 73. Note that in the description of the liquid ejection head 10E, descriptions similar to those of the liquid ejection heads 10 and 10B described above will be omitted.

[0092] 11, the piezoelectric body 53 is formed so as to be continuous in the Y-axis direction. The piezoelectric body 53 is also present on the partition walls 25c between the multiple pressure chambers C aligned in the Y-axis direction. The position of the top surface of the piezoelectric body 53 is constant in the Z-axis direction. For example, the position of the top surface of the piezoelectric body 53 on the individual electrode 51 is approximately the same as the position of the top surface of the piezoelectric body 53 on the partition wall 25c. The top surface of the piezoelectric body 53 is the surface closer to the common electrode 52 in the Z-axis direction.

[0093] The common electrode 52 is disposed on the piezoelectric body 53. The position of the upper surface of the common electrode 52 is constant in the Z-axis direction. For example, the position of the upper surface of the common electrode 52 on the individual electrode 51 and the position of the upper surface of the common electrode 52 on the partition wall 25c are substantially the same. The upper surface of the common electrode 52 is the surface closer to the VBS wiring 55 in the Z-axis direction, and the lower surface of the common electrode 52 is the surface closer to the piezoelectric body 53.

[0094] The VBS wiring 55 is disposed on the common electrode 52. The position of the upper surface of the VBS wiring 55 is constant in the Z-axis direction. For example, the position of the upper surface of the VBS wiring 55 on the individual electrode 51 and the position of the upper surface of the VBS wiring 55 on the partition wall 25c are substantially the same. The upper surface of the VBS wiring 55 is the surface closer to the sealed space in the Z-axis direction, and the lower surface of the VBS wiring 55 is the surface closer to the common electrode 52.

[0095] The thickness of the sealing plate 27 is constant above the plurality of piezoelectric elements 50. The position of the lower surface 27c of the sealing plate 27 is constant in the Z-axis direction above the plurality of piezoelectric elements 50. As described above, the sealing plate 27 does not have the protruding portion 27g formed thereon.

[0096] The liquid ejection head 10E includes a wiring portion 72E and a wiring portion 73E. The wiring portion 73E is provided between the VBS wiring 55 and the wiring portion 72E, and electrically connects the VBS wiring 55 and the wiring portion 72E. The "wiring portion 72E" is an example of a "second wiring portion," and the "wiring portion 73E" is an example of a "third wiring portion." The wiring portion 72E is provided on the lower surface 27C of the sealing plate 27. The wiring portion 72E extends in the Y-axis direction along the lower surface 27C of the sealing plate 27.

[0097] The wiring portion 73E electrically connects the wiring portion 72E and the VBS wiring 55 in the Z-axis direction. The wiring portion 73E is located above the partition wall 25C. The length of the wiring portion 72E along the X-axis direction may be approximately the same as the length of the common electrode 52 along the X-axis direction, for example. The wiring portion 73E may be a block body.

[0098] The liquid ejection head 10E according to the fifth embodiment also achieves the same effects as the liquid ejection head 10 according to the first embodiment. The liquid ejection head 10E may be configured to include a sealing plate 27 on which the protruding portion 27g is not formed. Because the piezoelectric element 53 is present below the wiring portion 73E, the VBS wiring 55 can be disposed at a position away from the pressure chamber substrate 25, and the length of the wiring portion 73E in the X-axis direction can be shortened. This prevents an increase in wiring resistance. Furthermore, because the common electrode 52 and the VBS wiring 55 are formed linearly when viewed in the X-axis direction, the lengths of the common electrode 52 and the VBS wiring 55 can be shortened. This prevents an increase in wiring resistance.

[0099] Example 6 Next, a liquid ejection head 10F according to Example 6 will be described. Fig. 12 is a plan view showing a pressure chamber substrate 25F of the liquid ejection head 10F according to Example 6. The liquid ejection head 10F according to Example 6 differs from the liquid ejection head 10 according to Example 1 in that it includes a plurality of nozzle arrays NAL, NBL, a pressure chamber substrate 25F instead of the pressure chamber substrate 25, and wiring portions 73FA, 73FB that are arranged at different positions in the Y-axis direction. Note that in the description of Example 6, descriptions that are the same as those of Examples 1 to 5 may be omitted.

[0100] The liquid ejection head 10F includes a pressure chamber substrate 25F. In FIG. 12, the positions of the nozzles NA and NB are indicated by dashed lines. Also in FIG. 12, the positions of the wiring portions 73FA and 73FB are indicated by two-dot chain lines. A plurality of pressure chambers CA and CB are formed in the pressure chamber substrate 25F. The pressure chambers CA and CB are spaced apart from each other in the X-axis direction. A plurality of pressure chambers CA aligned in the Y-axis direction constitute a pressure chamber row CAL. A plurality of pressure chambers CB aligned in the Y-axis direction constitute a pressure chamber row CBL.

[0101] The liquid ejection head 10F includes a plurality of nozzle arrays NAL and NBL. The nozzle arrays NAL and NBL are spaced apart from each other in the X-axis direction. The nozzle array NAL includes a plurality of nozzles NA aligned in the Y-axis direction. The nozzle array NBL includes a plurality of nozzles NB aligned in the Y-axis direction. The nozzles NA and NB are arranged at different positions in the Y-axis direction.

[0102] The pressure chamber array CAL includes a pressure chamber CA1 and a pressure chamber CA2. The "pressure chamber CA1" is an example of a "first pressure chamber." The "pressure chamber CA2" is an example of a "second pressure chamber." When viewed in the X-axis direction, the pressure chamber CB is arranged between the pressure chambers CA. In other words, when viewed in the X-axis direction, the pressure chamber CA is arranged between the pressure chambers CB. The pressure chamber CA is connected to the nozzle NA. The pressure chamber CB is connected to the nozzle NB. The pressure chamber CB is not connected to the nozzle NA. The pressure chamber CA is not connected to the nozzle NB.

[0103] The liquid ejection head 10F includes a wiring portion 73FA and a wiring portion 73FB. The wiring portion 73FA is an example of a "third wiring portion." The wiring portion 73B is an example of a "third wiring portion." The wiring portion 73FA is disposed between the plurality of pressure chambers CA in the Y-axis direction. The wiring portion 73FB is disposed between the plurality of pressure chambers CB in the Y-axis direction.

[0104] The wiring portion 73FA is electrically connected to the VBS wiring 55 that supplies voltage to the common electrode 52 of the piezoelectric element 50A corresponding to the pressure chamber CA. The wiring portion 73FA is electrically connected to the wiring portion 72 and the VBS wiring 55 on the A row side. The "A row side" includes those related to multiple pressure chambers CA.

[0105] The wiring portion 73FB is electrically connected to the VBS wiring 55 that supplies voltage to the common electrode 52 of the piezoelectric element 50B corresponding to the pressure chamber CB. The wiring portion 73FB is electrically connected to the wiring portion 72 and the VBS wiring 55 on the B row side. The "B row side" includes those related to the multiple pressure chambers CB.

[0106] In this way, in the liquid ejection head 10F, the pressure chambers CA on the row A side and the pressure chambers CB on the row B side are arranged at different positions in the Y-axis direction. The pressure chambers CA and CB do not have to be arranged at the same position in the Y-axis direction. In the liquid ejection head 10F, the wiring portion 73FA on the row A side and the wiring portion 73FB on the row B side are arranged at different positions in the Y-axis direction. The wiring portions 73FA and 73FB do not have to be arranged at the same position in the Y-axis direction.

[0107] <Liquid discharge device> Next, a liquid ejection device 1 equipped with a liquid ejection head 10 will be described with reference to Figs. 13 and 14. Fig. 13 is a schematic diagram showing the liquid ejection device 1 equipped with the liquid ejection head 10. The liquid ejection device 1 is equipped with the liquid ejection head 10 according to the first embodiment described above. Fig. 13 is a block diagram showing the liquid ejection device 1. Note that the liquid ejection device 1 is not limited to a configuration equipped with the liquid ejection head 10 according to the first embodiment. The liquid ejection device 1 may be equipped with any of the liquid ejection heads 10B to 10F according to the second to sixth embodiments, instead of the liquid ejection head 10 according to the first embodiment.

[0108] The liquid ejection device 1 is an inkjet printing device that ejects ink, 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 printing paper. Note that the medium PA is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0109] The liquid ejection device 1 includes a liquid ejection head 10 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 a medium PA, and a control unit 30. The control unit 30 is a control unit that controls the ejection of liquid.

[0110] Specific embodiments of the liquid container 2 include, for example, a cartridge that is detachable from the liquid ejection device 1, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. Any type of ink can be stored in the liquid container 2. The liquid ejection device 1 includes, for example, a plurality of liquid containers 2 corresponding to 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 the carriage 3.

[0111] The liquid ejection device 1 includes a circulation mechanism 8 that circulates ink. The circulation mechanism 8 includes a supply flow path 81 that supplies ink to the liquid ejection head 10, a recovery flow path 82 that recovers ink discharged from the liquid ejection head 10, and a pump 83 that transports the ink.

[0112] 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.

[0113] As shown in Fig. 14, the liquid ejection device 1 includes a linear encoder 6. The linear encoder 6 is provided at a position where it can detect the position of the carriage 3. The linear encoder 6 acquires information about the position of the carriage 3. The linear encoder 6 outputs an encoder signal to the control unit 30 as the carriage 3 moves.

[0114] The control unit 30 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 35. The storage unit 35 includes, for example, a ROM 36 and a RAM 37. The storage unit 35 may include an EEPROM or a PROM. The storage unit 35 can store print data Img supplied from the host computer. The storage unit 35 stores a control program for the liquid ejection device 1.

[0115] 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.

[0116] 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 the drive signal Com to the piezoelectric element 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 element 50.

[0117] The liquid ejection device 1 includes a 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, it 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.

[0118] 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 element 50 based on the print signal SI. The drive circuit 62 can select the piezoelectric element 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 determines the latch timing of the print data Img. The change signal CH determines the selection timing of the drive pulse included in the drive signal Com.

[0119] 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 element 50 to vary the pressure of the ink in the pressure chamber C, thereby ejecting ink from the nozzle N. The control unit 30 controls the ejection operation when performing a printing operation.

[0120] The liquid ejection head 10 described above can be applied to such a liquid ejection device 1. The liquid ejection device 1 equipped with the liquid ejection head 10 includes the wiring portions 72 and 73, which allows for a reduction in the wiring resistance of the VBS wiring 55. In the liquid ejection device 1, current delay to the common electrode 52 is suppressed. Furthermore, the protruding portion 27g of the sealing plate 27 and the wiring portion 73 are provided above the partition wall 25c, which presses the partition wall 25c from above and suppresses deformation. This suppresses bending of the partition wall 25c.

[0121] <Variation 1> In the liquid ejection head 10 according to the first embodiment, the protruding portion 27g of the sealing plate 27 protrudes downward, but the piezoelectric element 53 may be disposed on the partition wall 25c, and the piezoelectric element 53 on the partition wall 25c may protrude upward. This allows the common electrode 52 and the VBS wiring 55 on the partition wall 25c to be positioned close to the sealing plate 27. Alternatively, the protruding portion 27g of the sealing plate 27 may protrude downward, and the piezoelectric element 53 on the partition wall 25c may protrude upward.

[0122] It should be noted that the above-described embodiment merely shows 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 within the scope that does not deviate from the gist of the present invention.

[0123] In the above-mentioned first embodiment, the liquid ejection head 10 in which the liquid is circulated is illustrated, but the present invention may also be applied to a liquid ejection head 10 in which the liquid is not circulated.

[0124] In the above-described first embodiment, a case has been illustrated in which one nozzle N is connected to a total of two pressure chambers, one first pressure chamber CA and one second pressure chamber CB, but one nozzle N may also be connected to a total of four pressure chambers, two first pressure chambers CA adjacent to each other in the Y-axis direction and two second pressure chambers CB adjacent to each other in the Y-axis direction.

[0125] In the above-described embodiment, a serial type liquid ejection device is exemplified in which a carriage carrying a liquid ejection head 10 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 1 having a line head carrying multiple liquid ejection heads 10.

[0126] The liquid ejection device 1 exemplified in the above-described embodiment can be employed in various devices such as facsimile machines and copiers, as well as 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 color filters for display devices such as liquid crystal display panels. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board. Furthermore, a liquid ejection device that ejects a solution of an organic substance related to a living organism is used as a manufacturing device for manufacturing biochips, for example. [Explanation of symbols]

[0127] 1...liquid ejection device, 10...liquid ejection head, 25...pressure chamber substrate, 25c...partition wall, 27...sealing plate (sealing substrate), 27c...lower surface, 27e, 27f...lower surface (inclined surface), 27g...projection portion, C...pressure chamber, C1...pressure chamber (first pressure chamber), C2...pressure chamber (second pressure chamber), C3...pressure chamber (third pressure chamber), 50...piezoelectric element, 51...individual electrode, 52...common electrode, 53...piezoelectric body, 501...piezoelectric element (first piezoelectric element), 502...piezoelectric element (second piezoelectric element) ), 511...individual electrode (first individual electrode), 512...individual electrode (second individual electrode), 531...piezoelectric element (first piezoelectric element), 532...piezoelectric element (second piezoelectric element), 55...VBS wiring (first wiring portion), 60...COF, 61...flexible wiring board (wiring board), 72...wiring portion (second wiring portion), 73...wiring portion (third wiring portion, fourth wiring portion), N...nozzle, N1...nozzle (first nozzle), N2...nozzle (second nozzle), N3...nozzle (third nozzle).

Claims

1. A liquid ejection head, a nozzle substrate provided with a first nozzle that ejects a liquid and a second nozzle that is provided adjacent to the first nozzle and ejects a liquid; a pressure chamber substrate provided above the nozzle substrate, the pressure chamber substrate having a first pressure chamber communicating with the first nozzle and a second pressure chamber communicating with the second nozzle; a first piezoelectric element that is composed of a common electrode, a first piezoelectric body, and a first individual electrode and that applies pressure to the liquid in the first pressure chamber; a second piezoelectric element that is composed of the common electrode, a second piezoelectric body, and a second individual electrode and that applies pressure to the liquid in the second pressure chamber; a sealing substrate provided on the pressure chamber substrate so as to cover the first piezoelectric element and the second piezoelectric element; a wiring substrate for applying voltages to the common electrode, the first individual electrodes, and the second individual electrodes; a first wiring portion provided on the pressure chamber substrate and electrically connecting the common electrode and the wiring substrate; a second wiring portion provided on the lower surface of the sealing substrate and electrically connecting the common electrode and the wiring substrate; a third wiring portion provided between the first piezoelectric element and the second piezoelectric element, and electrically connecting the first wiring portion and the second wiring portion.

2. the nozzle substrate is further provided with a third nozzle that is disposed adjacent to the second nozzle and ejects a liquid; the pressure chamber substrate is further provided with a third pressure chamber communicating with the third nozzle; a third piezoelectric element that is composed of the common electrode, a third piezoelectric body, and a third individual electrode and that applies pressure to the liquid in the third pressure chamber; 2. The liquid ejection head according to claim 1, further comprising a fourth wiring portion provided between the second piezoelectric element and the third piezoelectric element, electrically connecting the first wiring portion and the second wiring portion.

3. the nozzle substrate is further provided with a third nozzle that is disposed adjacent to the second nozzle and ejects a liquid; the pressure chamber substrate is further provided with a third pressure chamber communicating with the third nozzle; a third piezoelectric element that is composed of the common electrode, a third piezoelectric body, and a third individual electrode and that applies pressure to the liquid in the third pressure chamber; 2. The liquid ejection head according to claim 1, wherein a wiring portion electrically connecting the first wiring portion and the second wiring portion is not provided between the second piezoelectric element and the third piezoelectric element.

4. 4. The liquid ejection head according to claim 1, wherein the second wiring portion is thicker than the first wiring portion.

5. 5. The liquid ejection head according to claim 1, wherein the third wiring portion is thicker than the first wiring portion and the second wiring portion.

6. 6. A liquid ejection head according to claim 1, wherein the thickness of the sealing substrate in the portion where the third wiring portion is provided is greater than the thickness of the portion where the third wiring portion is not provided.

7. the sealing substrate has a protruding portion that protrudes toward the pressure chamber substrate, 7. The liquid ejection head according to claim 1, wherein the third wiring portion is provided in correspondence with the protruding portion.

8. the protruding portion has an inclined surface that is inclined with respect to the upper surface of the pressure chamber substrate, 8. The liquid ejection head according to claim 7, wherein a portion of the second wiring portion closer to the third wiring portion is disposed along the inclined surface.

9. 9. The liquid ejection head according to claim 7, wherein the protruding portion is disposed at a position overlapping a partition wall that separates the first pressure chamber and the second pressure chamber when viewed in the thickness direction of the pressure chamber substrate.

10. In a direction in which the first pressure chamber and the second pressure chamber are adjacent to each other, 10. The liquid ejection head according to claim 1, wherein the width of the third wiring is shorter than the width of a partition wall between the first pressure chamber and the second pressure chamber.

11. the common electrode is provided on the first piezoelectric element and the second piezoelectric element; 11. The liquid ejection head according to claim 1, wherein the first wiring portion is provided on an upper surface of the common electrode.

12. 12. The liquid ejection head according to claim 1, wherein the first wiring portion, the second wiring portion, and the third wiring portion are formed from the same material.

13. 13. The liquid ejection head according to claim 1, wherein the first nozzle and the second nozzle are two adjacent nozzles among a plurality of nozzles constituting one nozzle row that communicates with the same common liquid chamber.

14. A liquid ejection head according to any one of claims 1 to 13; a control unit for controlling a discharge operation from the liquid discharge head.

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