Liquid discharge head and liquid discharge device

Abstract

To provide a technique that can reduce the possibility that burnout may occur in a piezoelectric body, in the vicinity of an end part of an electrode laminated on the piezoelectric body.SOLUTION: A liquid discharge head comprises: a piezoelectric body; a pressure chamber substrate in which a plurality of pressure chambers, in which the piezoelectric body is driven so that pressure is applied to liquid stored therein, are provided in line in an arranging direction; a first electrode provided at one side in a laminating direction with respect to the piezoelectric body; a second electrode provided at the other side in the laminating direction that is the opposite side of the one side, with respect to the piezoelectric body; and a protection layer formed at the other side, with respect to the piezoelectric body, in a boundary region which is a boundary between a first region and a second region in an extending direction, where a region where the piezoelectric body overlaps the second electrode in the laminating direction is defined as the first region and a region where the piezoelectric body exists but the second electrode does not exist in the laminating direction is defined as the second region. The protection layer includes a first inorganic film constituted of inorganic materials and a second inorganic film constituted of inorganic materials which is different from the first inorganic film. In the laminating direction, the first region overlaps the pressure chambers.SELECTED DRAWING: Figure 7

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a liquid jet head having a protective film that covers an area including the boundary between an area where the piezoelectric layer is not covered by an upper electrode and an area where the piezoelectric layer is covered by an upper electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-135611 Summary of the Invention [Problem to be solved by the invention]

[0004] When moisture gets into a crack that occurs in the piezoelectric body near the edge of an electrode laminated on the piezoelectric body, the two electrodes laminated on either side of the piezoelectric body may short-circuit, causing the piezoelectric body to burn. Therefore, there is a need for technology that can reduce the possibility of the piezoelectric body burning near the edge of the electrode laminated on the piezoelectric body. [Means for solving the problem]

[0005] According to a first aspect of the present disclosure, there is provided a liquid ejection head comprising: a pressure chamber substrate on which a plurality of pressure chambers are arranged in an arrangement direction intersecting an extension direction of the pressure chambers, the pressure chambers being driven by the piezoelectric elements to apply pressure to liquid stored therein; a first electrode provided on one side of the piezoelectric elements in a stacking direction intersecting the extension direction and the arrangement direction, the second electrode provided on the other side of the piezoelectric elements in the stacking direction opposite to the first side; and a protective layer provided on the other side of the piezoelectric elements in a boundary region between the first region and the second region in the extension direction, where the first region is defined as a region where the piezoelectric elements and the second electrode overlap in the stacking direction and the second region is defined as a region where the piezoelectric elements are present but the second electrode is not present in the stacking direction, the protective layer including a first inorganic film made of an inorganic material and a second inorganic film made of an inorganic material different from the first inorganic film, the first region overlapping with the pressure chambers in the stacking direction.

[0006] According to a second aspect of the present disclosure, there is provided a liquid ejection device including the liquid ejection head of the first aspect and a control unit that controls an ejection operation for ejecting liquid from the liquid ejection head. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device according to a first embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing the configuration of the liquid ejection head. [Figure 3] FIG. 2 is an explanatory diagram showing the configuration of a liquid ejection head in a plan view. [Figure 4] FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3. [Figure 5] 4 is an explanatory diagram showing an enlarged view of a part of an area AR in FIG. 3. FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5. [Figure 7] FIG. 2 is an enlarged cross-sectional view of the vicinity of a protective layer. [Figure 8] FIG. 10 is an enlarged cross-sectional view of the vicinity of a protective layer in a second embodiment. [Figure 9] FIG. 11 is an enlarged cross-sectional view of the vicinity of a protective layer in a third embodiment. [Figure 10] FIG. 10 is an enlarged cross-sectional view of the vicinity of a protective layer in a fourth embodiment. [Figure 11] FIG. 11 is an enlarged cross-sectional view of the vicinity of a protective layer in a fifth embodiment. [Figure 12] FIG. 10 is an enlarged cross-sectional view of the vicinity of a protective layer in another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] A. First embodiment: FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid ejection device 500 according to a first embodiment. In this embodiment, the liquid ejection device 500 is an inkjet printer that ejects ink, an example of a liquid, onto printing paper P to form an image. The liquid ejection device 500 may eject ink onto any type of medium, such as a resin film or fabric, instead of printing paper P. X, Y, and Z in FIG. 1 and the subsequent figures represent three mutually orthogonal spatial axes. In this specification, the directions along these axes are also referred to as the X-axis direction, Y-axis direction, and Z-axis direction. When specifying a direction, positive and negative signs are used in combination, with a positive direction indicated by "+" and a negative direction indicated by "-." The direction indicated by the arrow in each figure is referred to as the + direction and the opposite direction as the - direction. In this embodiment, the Z-axis direction coincides with the vertical direction, with the +Z direction indicating a vertically downward direction and the -Z direction indicating a vertically upward direction. Furthermore, when the positive and negative directions are not limited, the following description will be given assuming that the three X, Y, and Z are the X-axis, Y-axis, and Z-axis.

[0009] The liquid ejection device 500 includes a liquid ejection head 510, an ink tank 550, a transport mechanism 560, a movement mechanism 570, and a control unit 580. The liquid ejection head 510 has a plurality of nozzles formed therein and ejects ink of four colors, for example, black, cyan, magenta, and yellow, in the +Z direction to form an image on printing paper P. The liquid ejection head 510 is mounted on a carriage 572 and moves back and forth in the main scanning direction together with the movement of the carriage 572. In this embodiment, the main scanning direction is the +X direction and the -X direction. The liquid ejection head 510 is not limited to four colors, and may also eject any other color ink, such as light cyan, light magenta, clear, or white.

[0010] The ink tank 550 contains ink to be ejected from the liquid ejection head 510. The ink tank 550 is connected to the liquid ejection head 510 by a resin tube 552. The ink in the ink tank 550 is supplied to the liquid ejection head 510 via the tube 552. Note that instead of the ink tank 550, a bag-shaped liquid pack made of a flexible film may be provided.

[0011] The transport mechanism 560 transports the printing paper P in the sub-scanning direction. The sub-scanning direction is a direction that intersects with the X-axis direction, which is the main scanning direction, and in this embodiment, is the +Y direction and the -Y direction. The transport mechanism 560 includes a transport rod 564 to which three transport rollers 562 are attached, and a transport motor 566 that rotates the transport rod 564. The transport motor 566 rotates the transport rod 564, thereby transporting the printing paper P in the +Y direction, which is the sub-scanning direction. The number of transport rollers 562 is not limited to three and may be any number. Furthermore, a configuration may be provided with multiple transport mechanisms 560.

[0012] The movement mechanism 570 includes a carriage 572, a conveyor belt 574, a movement motor 576, and a pulley 577. The carriage 572 carries the liquid ejection head 510 that is ready to eject ink. The carriage 572 is fixed to the conveyor belt 574. The conveyor belt 574 is stretched between the movement motor 576 and the pulley 577. When the movement motor 576 is driven to rotate, the conveyor belt 574 moves back and forth in the main scanning direction. As a result, the carriage 572 fixed to the conveyor belt 574 also moves back and forth in the main scanning direction.

[0013] The control unit 580 is configured as a microcomputer including a CPU and a storage unit. The storage unit may be, for example, a non-volatile memory such as an EEPROM that can be erased with an electrical signal, a non-volatile memory such as a one-time PROM or an EPROM that can be erased with ultraviolet light, or a non-erasable non-volatile memory such as a PROM. The storage unit stores various programs for implementing the functions provided in this embodiment. The CPU unifies the control of each unit of the liquid ejection device 500 by expanding and executing the programs stored in the storage unit. The control unit 580 controls the reciprocating movement of the carriage 572 in the main scanning direction, the transport movement of the printing paper P in the sub-scanning direction, and the ejection operation of ejecting liquid from the liquid ejection head 510.

[0014] The detailed configuration of the liquid ejection head 510 will be described with reference to FIGS. 2 to 4. FIG. 2 is an exploded perspective view showing the configuration of the liquid ejection head 510. FIG. 3 is an explanatory diagram showing the configuration of the liquid ejection head 510 in a plan view. In this disclosure, "plan view" refers to a state in which an object is viewed along the stacking direction, which will be described later. FIG. 3 shows the configuration of the liquid ejection head 510, including the pressure chamber substrate 10 and the diaphragm 50, and omits the protective layer 82, sealing substrate 30, case member 40, etc., to facilitate understanding of the technology. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3.

[0015] The liquid ejection head 510 includes the pressure chamber substrate 10, the communication plate 15, the nozzle plate 20, the compliance substrate 45, the vibration plate 50, the sealing substrate 30, the case member 40, the wiring substrate 120, and the piezoelectric element 300 shown in FIG. 3. The liquid ejection head 510 is formed by stacking these laminated members. In the present disclosure, the direction in which the laminated members that form the liquid ejection head 510 are stacked is also referred to as the "stacking direction." In this embodiment, the stacking direction coincides with the Z-axis direction. In the present disclosure, the +Z direction side with respect to a predetermined reference position is also referred to as "one side of the stacking direction" or "lower side," and the -Z direction side is also referred to as "the other side of the stacking direction" or "upper side."

[0016] The pressure chamber substrate 10 is formed using, for example, a silicon substrate, a glass substrate, an SOI substrate, or various ceramic substrates. As shown in FIG. 3 , a plurality of pressure chambers 12 are formed in the pressure chamber substrate 10. The ink flow paths formed in the pressure chamber substrate 10, such as the pressure chambers 12, are formed by anisotropically etching the surface of the pressure chamber substrate 10 on the +Z direction side. The pressure chambers 12 extend along the X-axis direction. Specifically, the pressure chambers 12 are formed in a substantially rectangular shape whose length in the X-axis direction is longer than its length in the Y-axis direction in a plan view. The shape of the pressure chambers 12 is not limited to a rectangular shape and may be a parallelogram, polygon, oval, or the like. An oval shape refers to a shape that is based on a rectangular shape and has semicircular ends at both longitudinal ends, and includes a rounded rectangle, an ellipse, an egg shape, and the like. In this disclosure, the X-axis direction is also referred to as the "extension direction."

[0017] As shown in FIG. 3, the pressure chambers 12 are arranged in the pressure chamber substrate 10 in a direction intersecting the extension direction. In a plan view of the liquid ejection head 510 viewed along the stacking direction, the direction in which the pressure chambers 12 are arranged is also referred to as the "arrangement direction." That is, the arrangement direction is a direction intersecting the extension direction and the stacking direction. In this embodiment, the pressure chambers 12 are arranged in two parallel rows, with the Y-axis direction as the arrangement direction. In the example of FIG. 3, the pressure chamber substrate 10 has two pressure chamber rows: a first pressure chamber row L1 having a first arrangement direction parallel to the Y-axis direction, and a second pressure chamber row L2 having a second arrangement direction parallel to the Y-axis direction. The first pressure chamber row L1 and the second pressure chamber row L2 are arranged on both sides of the wiring substrate 120. Specifically, the second pressure chamber row L2 is arranged on the opposite side of the wiring substrate 120 from the first pressure chamber row L1 in the X-axis direction, which is the extension direction. 3, the second pressure chamber row L2 is arranged in the −X direction with respect to the first pressure chamber row L1, sandwiching the wiring substrate 120. All of the pressure chambers 12 do not necessarily need to be arranged in a straight line, and for example, the pressure chambers 12 may be arranged in a staggered arrangement along the Y axis direction, in which every other pressure chamber 12 is arranged in the intersecting direction.

[0018] As shown in FIG. 2, a communication plate 15, a nozzle plate 20, and a compliance substrate 45 are stacked on the +Z direction side of the pressure chamber substrate 10. The communication plate 15 is a flat plate-like member made of, for example, a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, or a metal substrate. Examples of metal substrates include a stainless steel substrate. The communication plate 15 is provided with a nozzle communication passage 16, a first manifold portion 17, a second manifold portion 18 shown in FIG. 4, and a supply communication passage 19. It is preferable that the communication plate 15 be made of a material with approximately the same thermal expansion coefficient as that of the pressure chamber substrate 10. This makes it possible to suppress warping of the pressure chamber substrate 10 and the communication plate 15 due to differences in thermal expansion coefficients when the temperatures of the pressure chamber substrate 10 and the communication plate 15 change.

[0019] As shown in Fig. 4, the nozzle communication passage 16 is a flow path that communicates between the pressure chambers 12 and the nozzles 21. The first manifold portion 17 and the second manifold portion 18 function as part of a manifold 100 that serves as a common liquid chamber through which the multiple pressure chambers 12 communicate. The first manifold portion 17 is provided so as to penetrate the communication plate 15 in the Z-axis direction. Furthermore, as shown in Fig. 4, the second manifold portion 18 is provided on the surface of the communication plate 15 on the +Z direction side, without penetrating the communication plate 15 in the Z-axis direction.

[0020] As shown in FIG. 4 , the supply communication passage 19 is a flow path connected to a pressure chamber supply path 14 provided in the pressure chamber substrate 10. The pressure chamber supply path 14 is a flow path connected to one end of the pressure chamber 12 in the X-axis direction via a throttle portion 13. The throttle portion 13 is a flow path provided between the pressure chamber 12 and the pressure chamber supply path 14. The throttle portion 13 is a flow path whose inner wall protrudes further than the pressure chamber 12 and the pressure chamber supply path 14 and is formed narrower than the pressure chamber 12 and the pressure chamber supply path 14. As a result, the throttle portion 13 has a higher flow path resistance than the pressure chamber 12 and the pressure chamber supply path 14. With this configuration, it is possible to suppress or prevent ink in the pressure chamber 12 from flowing back into the pressure chamber supply path 14 even when pressure is applied to the pressure chamber 12 by the piezoelectric element 300 during ink ejection. There are multiple supply communication passages 19, which are arranged in the Y-axis direction, i.e., the arrangement direction, and are individually provided for each pressure chamber 12. The supply communication passage 19 and the pressure chamber supply passage 14 connect the second manifold portion 18 to each pressure chamber 12, and supply ink in the manifold 100 to each pressure chamber 12.

[0021] The nozzle plate 20 is provided on the opposite side of the communicating plate 15 from the pressure chamber substrate 10, i.e., on the surface of the communicating plate 15 in the +Z direction. The material of the nozzle plate 20 is not particularly limited, and examples thereof include a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, and a metal substrate. Examples of metal substrates include a stainless steel substrate. The nozzle plate 20 can also be made of an organic material such as a polyimide resin. However, it is preferable to use a material for the nozzle plate 20 with approximately the same thermal expansion coefficient as the communicating plate 15. This makes it possible to suppress warping of the nozzle plate 20 and the communicating plate 15 due to differences in thermal expansion coefficients when the temperatures of the nozzle plate 20 and the communicating plate 15 change.

[0022] A plurality of nozzles 21 are formed in the nozzle plate 20. Each nozzle 21 is connected to a corresponding pressure chamber 12 via a nozzle communication passage 16. As shown in FIG. 2, the plurality of nozzles 21 are arranged along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. The nozzle plate 20 is provided with two nozzle rows, each of which has a plurality of nozzles 21 arranged in a row. The two nozzle rows correspond to the first pressure chamber row L1 and the second pressure chamber row L2, respectively.

[0023] As shown in FIG. 4, the compliance substrate 45 is provided together with the nozzle plate 20 on the side opposite the pressure chamber substrate 10 across the communicating plate 15, i.e., on the surface of the communicating plate 15 on the +Z direction side. The compliance substrate 45 is provided around the nozzle plate 20 and covers the openings of the first manifold section 17 and the second manifold section 18 provided in the communicating plate 15. The compliance substrate 45 includes, for example, a sealing film 46 made of a flexible thin film, and a fixed substrate 47 made of a hard material such as metal. As shown in FIG. 4, the region of the fixed substrate 47 facing the manifold 100 is completely removed in the thickness direction to define an opening 48. Therefore, one side of the manifold 100 forms a compliance section 49 sealed only by the sealing film 46.

[0024] As shown in Fig. 4, a vibration plate 50 and a piezoelectric element 300 are laminated on the side of the pressure chamber substrate 10 opposite the communicating plate 15, etc., i.e., on the surface on the -Z direction side of the pressure chamber substrate 10. The piezoelectric element 300 flexibly deforms the vibration plate 50, causing a pressure change in the ink inside the pressure chamber 12. In Fig. 4, the illustration of the piezoelectric element 300 is simplified.

[0025] The diaphragm 50 is provided between the piezoelectric element 300 and the pressure chamber substrate 10. The diaphragm 50 is provided at a position closer to the pressure chamber substrate 10 than the piezoelectric element 300, and includes an elastic film 55 made of silicon oxide (SiO2), and an insulating film 56 made of zirconium oxide (ZrO2) provided on the elastic film 55. The elastic film 55 forms the surface on the -Z direction side of the flow path of the pressure chamber 12, etc. Note that the diaphragm 50 may be composed of, for example, either the elastic film 55 or the insulating film 56, or may include other films in addition to the elastic film 55 and the insulating film 56. Examples of materials for the other films include silicon, silicon nitride, etc.

[0026] As shown in FIG. 2, a sealing substrate 30 having substantially the same size as the pressure chamber substrate 10 in a plan view is bonded to the surface of the pressure chamber substrate 10 on the -Z direction side with an adhesive or the like. As shown in FIG. 4, the sealing substrate 30 includes a ceiling portion 30T, a wall portion 30W, a holding portion 31, and a through-hole 32. The holding portion 31 is a space defined by the ceiling portion 30T and the wall portion 30W, and houses the piezoelectric elements 300 to protect the active portions of the piezoelectric elements 300. In this embodiment, a holding portion 31 is provided for each row of the piezoelectric elements 300. More specifically, two holding portions 31 corresponding to the first pressure chamber row L1 and the second pressure chamber row L2 are formed adjacent to each other. The through-hole 32 penetrates the sealing substrate 30 along the Z-axis direction. In a plan view, the through-hole 32 is disposed between the two holding portions 31 and has a rectangular shape that is elongated along the Y-axis direction.

[0027] 4, a case member 40 is fixed on the sealing substrate 30. The case member 40 forms a manifold 100, which communicates with the multiple pressure chambers 12, together with the communication plate 15. The case member 40 has approximately the same outer shape as the communication plate 15 in a plan view, and is joined to cover the sealing substrate 30 and the communication plate 15.

[0028] The case member 40 has a storage section 41, a supply port 44, a third manifold section 42, and a connection port 43. The storage section 41 is a space deep enough to accommodate the pressure chamber substrate 10, the vibration plate 50, and the sealing substrate 30. The third manifold section 42 is a space formed in the case member 40 near both ends of the storage section 41 in the X-axis direction. The third manifold section 42 is connected to the first manifold section 17 and the second manifold section 18 provided on the communication plate 15, thereby forming a manifold 100. The manifold 100 has an elongated shape in the Y-axis direction. The supply port 44 communicates with the manifolds 100 and supplies ink to each manifold 100. The connection port 43 is a through hole that communicates with the through hole 32 of the sealing substrate 30, and a wiring substrate 120 is inserted through the through hole 43.

[0029] 1 through the supply port 44 shown in Fig. 4, and fills the internal flow paths from the manifold 100 to the nozzles 21 with ink. Then, a voltage based on a drive signal is applied to each of the piezoelectric elements 300 corresponding to the plurality of pressure chambers 12. This causes the vibration plate 50 to bend and deform together with the piezoelectric elements 300, changing the volume of each pressure chamber 12 and increasing the internal pressure, causing ink droplets to be ejected from each nozzle 21.

[0030] The configuration of the piezoelectric element 300 will be described with appropriate reference to Figures 5 and 6 in addition to Figures 3 and 4. Figure 5 is an explanatory diagram showing an enlarged view of a part of the range AR in Figure 3. Figure 6 is a cross-sectional view showing the position VI-VI in Figure 5.

[0031] 6, the piezoelectric element 300 has a first electrode 60, a piezoelectric body 70, and a second electrode 80. The first electrode 60, the piezoelectric body 70, and the second electrode 80 are stacked in this order toward the −Z direction of the stacking direction. The piezoelectric body 70 is provided between the first electrode 60 and the second electrode 80 in the stacking direction. The first electrode 60 is provided on the +Z direction side of the piezoelectric body 70, and the second electrode 80 is provided on the −Z direction side of the piezoelectric body 70.

[0032] As shown in FIG. 5, the first electrode 60 and the second electrode 80 are electrically connected to the wiring substrate 120 shown in FIG. 4 via drive wiring. The drive wiring includes a first drive wiring 91 that electrically connects the wiring substrate 120 and the first electrode 60, and a second drive wiring 92 that electrically connects the wiring substrate 120 and the second electrode 80. The first electrode 60 and the second electrode 80 apply a voltage corresponding to a drive signal to the piezoelectric body 70. The drive voltage is a voltage that is applied to the piezoelectric element 300 from the first electrode 60 and the second electrode 80 by the control unit 580 to drive the piezoelectric element 300. A portion of the piezoelectric element 300 where piezoelectric strain occurs in the piezoelectric body 70 when a voltage is applied between the first electrode 60 and the second electrode 80 is also referred to as an active portion.

[0033] A driving voltage that varies depending on the amount of ink ejected is applied to the first electrode 60, and a predetermined reference voltage is applied to the second electrode 80 regardless of the amount of ink ejected. When a voltage difference occurs between the first electrode 60 and the second electrode 80 due to the application of the driving voltage and the reference voltage, the piezoelectric body 70 of the piezoelectric element 300 deforms. The deformation of the piezoelectric body 70 causes the vibration plate 50 to deform or vibrate, changing the volume of the pressure chamber 12. As the volume of the pressure chamber 12 changes, pressure is applied to the ink contained in the pressure chamber 12, and ink is ejected from the nozzle 21 via the nozzle communication passage 16.

[0034] In this embodiment, the first electrodes 60 are individual electrodes provided for the multiple pressure chambers 12. As shown in FIG. 6, the first electrodes 60 are lower electrodes provided on the opposite side of the piezoelectric body 70 from the second electrode 80, i.e., below the piezoelectric body 70. The first electrodes 60 are formed to a thickness of, for example, approximately 80 nanometers. The first electrodes 60 are formed of a conductive material, for example, a metal such as platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti), or a conductive metal oxide such as indium tin oxide (ITO). The first electrodes 60 may be formed by laminating multiple materials, such as platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti). In this embodiment, platinum (Pt) is used as the first electrodes 60.

[0035] As shown in FIG. 3, the piezoelectric body 70 has a predetermined width in the X-axis direction and a rectangular shape that is long along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. The thickness of the piezoelectric body 70 is, for example, about 1000 to 4000 nanometers. The piezoelectric body 70 may be a crystalline film with a perovskite structure, so-called perovskite crystal, made of a ferroelectric ceramic material that exhibits electromechanical conversion and is formed on the first electrode 60. The piezoelectric body 70 may be made of, for example, a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), or a material to which a metal oxide such as niobium oxide, nickel oxide, or magnesium oxide is added. Specifically, lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead magnesium zirconium titanate (Pb(Zr,Ti)(Mg,Nb)O3), etc. In this embodiment, lead zirconate titanate (PZT) is used as the piezoelectric body 70.

[0036] The material of the piezoelectric body 70 is not limited to lead-based piezoelectric materials containing lead, but lead-free piezoelectric materials can also be used. Examples of lead-free piezoelectric materials include bismuth ferrite ((BiFeO3), abbreviated as "BFO"), barium titanate ((BaTiO3), abbreviated as "BT"), potassium sodium niobate ((K,Na)(NbO3), abbreviated as "KNN"), potassium sodium lithium niobate ((K,Na,Li)(NbO3)), potassium sodium lithium tantalate niobate ((K,Na,Li)(Nb,Ta)O3), bismuth potassium titanate ((Bi 1 / 2 K 1 / 2 )TiO3, abbreviated as "BKT"), bismuth sodium titanate ((Bi 1 / 2 Na 1 / 2 )TiO3, abbreviated as "BNT"), bismuth manganate (BiMnO3, abbreviated as "BM"), and complex oxides containing bismuth, potassium, titanium, and iron and having a perovskite structure (x[(Bi x K 1-x )TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), complex oxides containing bismuth, iron, barium and titanium and having a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and oxides to which metals such as manganese, cobalt and chromium have been added ((1-x)[Bi(Fe 1-y M y )O3]-x[BaTiO3] (M is Mn, Co, or Cr).

[0037] As shown in FIG. 3, the second electrode 80 is a common electrode provided in common to the multiple pressure chambers 12. The second electrode 80 has a predetermined width in the X-axis direction and extends along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. As shown in FIG. 6, the second electrode 80 is an upper electrode provided on the opposite side of the piezoelectric body 70 from the first electrode 60, i.e., above the piezoelectric body 70. As with the first electrode 60, the second electrode 80 is made of a conductive material such as a metal, e.g., platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti), or a conductive metal oxide, e.g., indium tin oxide (ITO). The second electrode 80 may be formed by stacking multiple materials, e.g., platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti). In this embodiment, iridium (Ir) is used as the second electrode 80.

[0038] As shown in FIG. 6 , a wiring portion 85 is provided on the −X-direction side of the −X-direction end portion 80b of the second electrode 80. The wiring portion 85 is not shown in FIGS. 3 and 5 . The wiring portion 85 is formed in the same layer as the second electrode 80 but is electrically discontinuous with the second electrode 80. The wiring portion 85 is formed from the −X-direction end portion 70b of the piezoelectric body 70 to the −X-direction end portion 60b of the first electrode 60, spaced apart from the end portion 80b of the second electrode 80. The −X-direction end portion 60b of the first electrode 60 extends further to the outside than the end portion 70b of the piezoelectric body 70. A plurality of wiring portions 85 are provided for each piezoelectric element 300, and are arranged at predetermined intervals along the Y-axis direction. It is preferable that the wiring portion 85 is formed in the same layer as the second electrode 80. This simplifies the manufacturing process of the wiring portion 85 and reduces costs. However, the wiring portion 85 may be formed in a layer separate from the second electrode 80.

[0039] 5 and 6, a first drive wiring 91 is electrically connected to the first electrode 60, which is an individual electrode, and an extension portion 92a and an extension portion 92b of a second drive wiring 92 are electrically connected to the second electrode 80, which is a common electrode. The first drive wiring 91 and the second drive wiring 92 function as drive wiring for applying a voltage for driving the piezoelectric body 70 from the wiring substrate 120.

[0040] The first drive wiring 91 is provided individually for each first electrode 60. As shown in Fig. 6, the first drive wiring 91 is connected to the vicinity of one end 60b of the first electrode 60 via a wiring section 85, and is drawn out in the -X direction onto the diaphragm 50. The first drive wiring 91 is electrically connected to one end 60b of the first electrode 60 in the -X direction, which is drawn out further to the outside than one end 70b of the piezoelectric body 70. Note that the wiring section 85 may be omitted, and the first drive wiring 91 may be directly connected to one end 60b of the first electrode 60.

[0041] 3, the second drive wiring 92 extends along the Y-axis direction, bends at both ends in the Y-axis direction, and is drawn out along the X-axis direction. The second drive wiring 92 has an extension portion 92a and an extension portion 92b that extend along the Y-axis direction. As shown in FIGS. 3 and 4, the ends of the first drive wiring 91 and the second drive wiring 92 extend so as to be exposed in the through-hole 32 of the sealing substrate 30, and are electrically connected to the wiring substrate 120 within the through-hole 32.

[0042] The first drive wiring 91 and the second drive wiring 92 are made of a conductive material, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), or aluminum (Al). In this embodiment, gold (Au) is used for the first drive wiring 91 and the second drive wiring 92. In this embodiment, the first drive wiring 91 and the second drive wiring 92 are formed by sputtering. However, the first drive wiring 91 and the second drive wiring 92 may be formed by any known film formation technique, not limited to sputtering.

[0043] The first drive wiring 91 and the second drive wiring 92 are formed in the same layer while being electrically discontinuous with each other. This allows the first drive wiring 91 and the second drive wiring 92 to be formed using a common process, which simplifies the manufacturing process and suppresses a decrease in productivity of the liquid ejection head 510 compared to when the first drive wiring 91 and the second drive wiring 92 are formed separately. However, the first drive wiring 91 and the second drive wiring 92 may be formed in different layers. The first drive wiring 91 and the second drive wiring 92 may have an adhesion layer that improves adhesion with the first electrode 60, the second electrode 80, and the vibration plate 50.

[0044] The wiring board 120 is configured, for example, by a flexible printed circuit (FPC). A plurality of wires are formed on the wiring board 120 for connection to the control unit 580 and a power supply circuit (not shown). Note that instead of an FPC, the wiring board 120 may be configured by any flexible substrate, such as an FFC (Flexible Flat Cable). An integrated circuit 121 having a switching element and the like is mounted on the wiring board 120. A command signal for driving the piezoelectric element 300 and the like are input to the integrated circuit 121. The integrated circuit 121 controls the timing of supplying a drive signal for driving the piezoelectric element 300 to the first electrode 60 based on the command signal.

[0045] 5, the protective layer 82 is formed at a position overlapping an end of the second electrode 80 in a plan view of the liquid ejection head 510. Furthermore, as shown in Fig. 6, the protective layer 82 is formed so as to cover one end 80b of the second electrode 80 on the -X direction side and the surface of the piezoelectric body 70. The protective layer 82 is formed to a thickness of, for example, about 100 nanometers.

[0046] 7 is an enlarged cross-sectional view of the vicinity of the protective layer 82. In this specification, as shown in FIG. 7, the region where the piezoelectric body 70 and the second electrode 80 overlap in the Z-axis direction, which is the stacking direction, is called the first region, the region where the piezoelectric body 70 is present but the second electrode 80 is not present in the stacking direction is called the second region, and the region that is the boundary between the first region and the second region in the X-axis direction, which is the extension direction, is called the boundary region. In the boundary region, the protective layer 82 is provided on the -Z direction side of the piezoelectric body 70 and the second electrode 80. Furthermore, in the second region, the protective layer 82 is provided on the -Z direction side of the piezoelectric body 70.

[0047] The protective layer 82 includes a first inorganic film 821 and a second inorganic film 822. The second inorganic film 822 is laminated on the −Z direction side of the piezoelectric body 70, and the first inorganic film 821 is laminated on the −Z direction side of the second inorganic film 822. The first inorganic film 821 is made of a water-resistant inorganic material. In this embodiment, the first inorganic film 821 is made of aluminum oxide (AlO x The second inorganic film 822 is made of an inorganic material different from the first inorganic film 821, and is made of an inorganic material having insulating properties. In this embodiment, the second inorganic film 822 is made of silicon oxide (SiO x ). The second inorganic film 822 is formed so that its thickness in the stacking direction is greater than the thickness of the first inorganic film 821 in the stacking direction. The first inorganic film 821 and the second inorganic film 822 are formed by a method such as sputtering, chemical vapor deposition, atomic layer deposition, or vapor deposition. Note that the first inorganic film 821 is made of titanium oxide (TiO ) instead of aluminum oxide. x ), tantalum oxide (TaO x ), hafnium oxide (HfO x ), or may be composed of a plurality of these inorganic materials. Also, the second inorganic film 822 may be made of silicon nitride (SiN x ) and silicon carbide (SiC x ) or may be composed of a plurality of these inorganic substances.

[0048] According to the liquid ejection head 510 of the first embodiment described above, in a boundary region where one end 80b of the second electrode 80 in the extension direction is located, a protective layer 82 is formed on the other side of the stacking direction, that is, the −Z direction side, of the piezoelectric body 70. The protective layer 82 includes a first inorganic film 821 made of an inorganic material and a second inorganic film 822 made of an inorganic material different from the first inorganic film 821. Because the protective layer 82 is made of two films, the first inorganic film 821 and the second inorganic film 822, even if one film has a pinhole or contains foreign matter, the piezoelectric body 70 is covered by the other film, thereby preventing moisture from entering the piezoelectric body 70 near the one end 80b of the second electrode 80. Furthermore, compared to when either film of the protective layer 82 is made of an organic material that easily absorbs moisture, such as polyimide, the intrusion of moisture into the piezoelectric body 70 near the one end 80b of the second electrode 80 can be prevented. As a result, the possibility of the piezoelectric body 70 being burned near the one end 80b of the second electrode 80 can be reduced.

[0049] Furthermore, in this embodiment, the first inorganic film 821 is water resistant. Therefore, even if a crack occurs in the piezoelectric body 70 near one end 80b of the second electrode 80, it is possible to prevent moisture from entering the crack. Furthermore, in this embodiment, the second inorganic film 822 is insulating. Therefore, even if moisture enters a crack that occurs in the piezoelectric body 70 near one end 80b of the second electrode 80, it is possible to prevent a short circuit between the first electrode 60 and the second electrode 80.

[0050] In this embodiment, the second inorganic film 822 is laminated on the −Z direction side of the piezoelectric body 70, and the first inorganic film 821 is laminated on the −Z direction side of the second inorganic film 822. Since the water-resistant first inorganic film 821 is provided on the outermost side of the protective layer 82, it is possible to prevent moisture from entering the second inorganic film 822 and the piezoelectric body 70.

[0051] Furthermore, in this embodiment, the thickness of the second inorganic film 822 in the stacking direction is greater than the thickness of the first inorganic film 821 in the stacking direction. As shown in Fig. 4, since the sealing substrate 30 is provided on the -Z direction side of the piezoelectric element 300, there is an upper limit to the thickness of the protective layer 82 in the stacking direction. According to this embodiment, the thickness of the second inorganic film 822, which has insulating properties, is greater than the thickness of the first inorganic film 821, which has water resistance, and therefore the insulating properties of the protective layer 82 can be improved.

[0052] In this embodiment, the protective layer 82 is provided on the −Z direction side of the piezoelectric body 70 in the second region, which is a region in the stacking direction where the piezoelectric body 70 is present but the second electrode 80 is not present. This makes it possible to prevent moisture from entering the piezoelectric body 70 from the second region.

[0053] Furthermore, the liquid ejection device 500 of this embodiment includes a liquid ejection head 510 and a control unit 580 that controls an ejection operation for ejecting liquid from the liquid ejection head 510. Therefore, in the liquid ejection device 500, it is possible to reduce the possibility that the piezoelectric body 70 will be burned near the end of the second electrode 80 included in the liquid ejection head 510.

[0054] Furthermore, in this embodiment, the protective layer 82 covers the one end 80b of the second electrode 80, thereby suppressing or preventing peeling from the one end 80b of the second electrode 80. Furthermore, by covering the one end 80b, it is possible to suppress driving of the piezoelectric element 300 near the end of the active part of the piezoelectric element 300.

[0055] B. Second embodiment: 8 is an enlarged cross-sectional view of the vicinity of the protective layer 82b in the second embodiment. The configuration of each part of the liquid ejection device 500 in the second embodiment other than the protective layer 82b is the same as that in the first embodiment.

[0056] In the second embodiment, the first inorganic film 821b is laminated on the −Z direction side of the piezoelectric body 70, and the second inorganic film 822b is laminated on the −Z direction side of the first inorganic film 821b. The second inorganic film 822b is formed so that its thickness in the lamination direction is thinner than the thickness of the first inorganic film 821b in the lamination direction. The first inorganic film 821b is made of the same inorganic material as the first inorganic film 821 in the first embodiment, and the second inorganic film 822b is made of the same inorganic material as the second inorganic film 822 in the first embodiment.

[0057] According to the liquid ejection head 510 of the second embodiment described above, the first inorganic film 821b is laminated on the −Z direction side of the piezoelectric body 70, and the second inorganic film 822b is laminated on the −Z direction side of the first inorganic film 821b. Since the water-resistant first inorganic film 821b is provided closer to the piezoelectric body 70 than the insulating second inorganic film 822b, the possibility of moisture getting into the piezoelectric body 70 can be further reduced.

[0058] In this embodiment, the thickness of the insulating second inorganic film 822b in the stacking direction is thinner than the thickness of the water-resistant first inorganic film 821b in the stacking direction. As described above, there is an upper limit to the thickness of the protective layer 82b in the stacking direction, and therefore, according to this embodiment, the water resistance of the protective layer 82b can be improved.

[0059] C. Third embodiment: 9 is an enlarged cross-sectional view of the vicinity of the protective layer 82c in the third embodiment. The configuration of each part of the liquid ejection device 500 in the third embodiment other than the protective layer 82c is the same as in the first embodiment.

[0060] In the third embodiment, the protective layer 82c includes a first inorganic film 821c, a second inorganic film 822c, a third inorganic film 823, a fifth inorganic film 825, a sixth inorganic film 826, and a seventh inorganic film 827. The second inorganic film 822c is stacked on the -Z direction side of the piezoelectric body 70. The first inorganic film 821c is stacked on the -Z direction side of the second inorganic film 822c. The third inorganic film 823 is stacked on the -Z direction side of the first inorganic film 821c. The fifth inorganic film 825 is stacked on the -Z direction side of the third inorganic film 823. The sixth inorganic film 826 is stacked on the -Z direction side of the fifth inorganic film 825. The seventh inorganic film 827 is stacked on the -Z direction side of the sixth inorganic film 826. The third inorganic film 823 and the sixth inorganic film 826 are made of the same inorganic material as the inorganic material that makes up the second inorganic film 822c, and the fifth inorganic film 825 and the seventh inorganic film 827 are made of the same inorganic material as the inorganic material that makes up the first inorganic film 821c. Here, the first inorganic film 821c is made of the same inorganic material as the first inorganic film 821 in the first embodiment, and the second inorganic film 822c is made of the same inorganic material as the second inorganic film 822 in the first embodiment. In other words, the protective layer 82c is made of a plurality of water-resistant films and a plurality of insulating films that are alternately stacked.

[0061] According to the liquid ejection head 510 of the third embodiment described above, the second inorganic film 822c is laminated on the −Z direction side of the piezoelectric body 70, the first inorganic film 821c is laminated on the −Z direction side of the second inorganic film 822c, and the third inorganic film 823, which is made of the same inorganic material as the second inorganic film 822c, is laminated on the −Z direction side of the first inorganic film 821c. The third inorganic film 823 is an insulating film like the second inorganic film 822c. This further improves the insulating properties of the protective layer 82c.

[0062] Furthermore, in this embodiment, the protective layer 82 is constructed by alternately stacking multiple water-resistant films and multiple insulating films, so that even if some of the films have pinholes or contain foreign matter, the possibility of moisture entering the piezoelectric body 70 near one end 80b of the second electrode 80 can be further reduced.

[0063] D. Fourth embodiment: 10 is an enlarged cross-sectional view of the vicinity of the protective layer 82d in the fourth embodiment. The configuration of each part of the liquid ejection device 500 in the fourth embodiment other than the protective layer 82d is the same as that in the first embodiment.

[0064] In the fourth embodiment, the protective layer 82d includes a first inorganic film 821d, a second inorganic film 822d, a fourth inorganic film 824, an eighth inorganic film 828, a ninth inorganic film 829, and a tenth inorganic film 830. The first inorganic film 821d is stacked on the -Z direction side of the piezoelectric body 70. The second inorganic film 822d is stacked on the -Z direction side of the first inorganic film 821d. The fourth inorganic film 824 is stacked on the -Z direction side of the second inorganic film 822d. The eighth inorganic film 828 is stacked on the -Z direction side of the fourth inorganic film 824. The ninth inorganic film 829 is stacked on the -Z direction side of the eighth inorganic film 828. The tenth inorganic film 830 is stacked on the -Z direction side of the ninth inorganic film 829. The fourth inorganic film 824 and the ninth inorganic film 829 are made of the same inorganic material as the inorganic material that makes up the first inorganic film 821d, and the eighth inorganic film 828 and the tenth inorganic film 830 are made of the same inorganic material as the inorganic material that makes up the second inorganic film 822d. Here, the first inorganic film 821d is made of the same inorganic material as the first inorganic film 821 in the first embodiment, and the second inorganic film 822d is made of the same inorganic material as the second inorganic film 822 in the first embodiment. In other words, the protective layer 82d is made of a plurality of water-resistant films and a plurality of insulating films that are alternately stacked.

[0065] According to the liquid ejection head 510 of the fourth embodiment described above, the first inorganic film 821d is laminated on the −Z direction side of the piezoelectric body 70, the second inorganic film 822d is laminated on the −Z direction side of the first inorganic film 821d, and the fourth inorganic film 824, which is made of the same inorganic material as the first inorganic film 821d, is laminated on the −Z direction side of the second inorganic film 822d. The fourth inorganic film 824 is a film that is water-resistant like the first inorganic film 821d. This further improves the water resistance of the protective layer 82d.

[0066] Furthermore, in this embodiment, the protective layer 82d is constructed by alternately stacking multiple water-resistant films and multiple insulating films, so that even if some of the films have pinholes or contain foreign matter, the possibility of moisture entering the piezoelectric body 70 near one end 80b of the second electrode 80 can be further reduced.

[0067] E. Fifth embodiment: 11 is an enlarged cross-sectional view of the vicinity of the protective layer 82e in the fifth embodiment. The configuration of each part of the liquid ejection device 500 in the fifth embodiment other than the protective layer 82e is the same as that in the first embodiment.

[0068] In the fifth embodiment, the protective layer 82e is provided on the −Z direction side of the piezoelectric body 70 in a boundary region where one end 80b of the second electrode 80 in the extension direction is located, and is not provided on the −Z direction side of the piezoelectric body 70 in a second region where the piezoelectric body 70 is present but the second electrode 80 is not present in the stacking direction. The protective layer 82e is composed of a first inorganic film 821e and a second inorganic film 822e. The second inorganic film 822e is stacked on the −Z direction side of the piezoelectric body 70, and the first inorganic film 821e is stacked on the −Z direction side of the second inorganic film 822e. The first inorganic film 821e is composed of the same inorganic material as the first inorganic film 821 in the first embodiment, and the second inorganic film 822e is composed of the same inorganic material as the second inorganic film 822 in the first embodiment.

[0069] According to the liquid ejection head 510 of the fifth embodiment described above, in the boundary region where one end 80b of the second electrode 80 in the extension direction is located, the protective layer 82e is formed on the −Z direction side, which is the other side in the stacking direction, of the piezoelectric body 70, and therefore it is possible to prevent moisture from mixing into the piezoelectric body 70 near one end 80b of the second electrode 80. Furthermore, since the protective layer 82e is not formed on the −Z direction side of the piezoelectric body 70 in the second region, it is possible to reduce the size of the protective layer 82e in the extension direction while preventing moisture from mixing into the piezoelectric body 70.

[0070] F. Other Embodiments: (F-1) In the first embodiment, the thickness of the second inorganic film 822 in the stacking direction is greater than the thickness of the first inorganic film 821 in the stacking direction. In contrast, in the first embodiment, the thickness of the second inorganic film 822 in the stacking direction may be less than the thickness of the first inorganic film 821 in the stacking direction. According to this embodiment, the thickness of the water-resistant first inorganic film 821 is greater than the thickness of the insulating second inorganic film 822, and therefore the water resistance of the protective layer 82 can be improved.

[0071] (F-2) In the second embodiment, the thickness of the second inorganic film 822b in the stacking direction is thinner than the thickness of the first inorganic film 821b in the stacking direction. In contrast, in the second embodiment, the thickness of the second inorganic film 822b in the stacking direction may be thicker than the thickness of the first inorganic film 821b in the stacking direction. According to this embodiment, the thickness of the insulating second inorganic film 822b is thicker than the thickness of the water-resistant first inorganic film 821b, thereby improving the insulating properties of the protective layer 82b.

[0072] (F-3) In the above embodiment, the protective layer 82 is formed on the −Z direction side, which is the other side in the stacking direction, of the extended portion 92b of the second drive wiring 92. In contrast to this, as shown in FIG. 12 , the protective layer 82 may be formed between the second electrode 80 and the second drive wiring 92 in the stacking direction.

[0073] (F-4) In the above embodiment, the first inorganic film 821 is water resistant, and the second inorganic film 822 is insulating. In contrast, the first inorganic film 821 and the second inorganic film 822 may be made of different inorganic materials, and both the first inorganic film 821 and the second inorganic film 822 may be water resistant, or both may be insulating.

[0074] (F-5) In the third embodiment, the protective layer 82c includes a first inorganic film 821c, a second inorganic film 822c, a third inorganic film 823, a fifth inorganic film 825, a sixth inorganic film 826, and a seventh inorganic film 827. In contrast, the protective layer 82c does not necessarily include the fifth inorganic film 825, the sixth inorganic film 826, and the seventh inorganic film 827.

[0075] (F-6) In the fourth embodiment, the protective layer 82d includes a first inorganic film 821d, a second inorganic film 822d, a fourth inorganic film 824, an eighth inorganic film 828, a ninth inorganic film 829, and a tenth inorganic film 830. In contrast, the protective layer 82d does not necessarily include the eighth inorganic film 828, the ninth inorganic film 829, and the tenth inorganic film 830.

[0076] (F-7) In the third and fourth embodiments, the protective layers 82c and 82d are configured by alternately stacking three water-resistant films and three insulating films. In contrast, the protective layers 82c and 82d may be configured by alternately stacking a plurality of water-resistant films and a plurality of insulating films, and the number of water-resistant films and the number of insulating films included in the protective layers 82c and 82d are not limited to three.

[0077] G. Other forms: The present disclosure is not limited to the above-described embodiments and can be realized in various forms without departing from the spirit thereof. For example, the present disclosure can also be realized in the following forms. The technical features in the above embodiments corresponding to the technical features in each form described below can be appropriately replaced or combined to solve some or all of the problems of the present disclosure or to achieve some or all of the effects of the present disclosure. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0078] (1) According to a first aspect of the present disclosure, there is provided a liquid ejection head. This liquid ejection head comprises a piezoelectric body, a pressure chamber substrate on which pressure chambers are arranged in a row in an arrangement direction that intersects the extension direction of the pressure chambers, in which pressure is applied to liquid stored inside the piezoelectric body when the piezoelectric body is driven, a first electrode provided on one side of the piezoelectric body in a stacking direction that intersects the extension direction and the arrangement direction, a second electrode provided on the other side of the piezoelectric body in the stacking direction that is opposite to the one side, and a protective layer provided on the other side of the piezoelectric body in a boundary region that is the boundary between the first region and the second region in the extension direction, where the region where the piezoelectric body and the second electrode overlap in the stacking direction is defined as a first region and the region in the stacking direction where the piezoelectric body is present but the second electrode is not present, and the protective layer includes a first inorganic film made of an inorganic material and a second inorganic film made of an inorganic material different from the first inorganic film, and the first region overlaps with the pressure chambers in the stacking direction. According to this configuration, it is possible to prevent moisture from entering the piezoelectric body near the end of the second electrode located in the boundary region, thereby reducing the possibility of the piezoelectric body being burned near the end of the second electrode.

[0079] (2) In the above aspect, the first inorganic film may be water resistant, and the second inorganic film may be insulating. According to this configuration, it is possible to prevent moisture from entering cracks that occur in the piezoelectric body near the ends of the second electrode, and it is also possible to prevent a short circuit between the first electrode and the second electrode if moisture enters the cracks.

[0080] (3) In the above aspect, the first inorganic film may contain at least one of aluminum oxide, titanium oxide, tantalum oxide, and hafnium oxide.

[0081] (4) In the above embodiment, the second inorganic film may include at least one of silicon oxide, silicon nitride, and silicon carbide.

[0082] (5) In the above embodiment, the second inorganic film may be laminated on the other side of the piezoelectric body, and the first inorganic film may be laminated on the other side of the second inorganic film. According to this embodiment, it is possible to prevent moisture from entering the second inorganic film and the piezoelectric body.

[0083] (6) In the above embodiment, the second inorganic film may have a thickness in the stacking direction that is greater than that of the first inorganic film. According to this embodiment, when the thickness of the protective layer in the stacking direction is limited, the insulating properties of the protective layer can be improved.

[0084] (7) In the above embodiment, the second inorganic film may have a thickness in the stacking direction that is smaller than that of the first inorganic film. According to this embodiment, when the thickness of the protective layer in the lamination direction is limited, the water resistance of the protective layer can be improved.

[0085] (8) In the above embodiment, a third inorganic film may be further provided, the third inorganic film being made of the inorganic material that constitutes the second inorganic film and being laminated on the other side of the first inorganic film. According to this embodiment, the insulating properties of the protective layer can be further improved.

[0086] (9) In the above aspect, the first inorganic film may be laminated on the other side of the piezoelectric body, and the second inorganic film may be laminated on the other side of the first inorganic film. According to this embodiment, the possibility of moisture getting into the piezoelectric body can be further reduced.

[0087] (10) In the above embodiment, the second inorganic film may have a thickness in the stacking direction that is smaller than that of the first inorganic film. According to this embodiment, when the thickness of the protective layer in the lamination direction is limited, the water resistance of the protective layer can be improved.

[0088] (11) In the above embodiment, the second inorganic film may have a thickness in the stacking direction that is greater than that of the first inorganic film. According to this embodiment, when the thickness of the protective layer in the stacking direction is limited, the insulating properties of the protective layer can be improved.

[0089] (12) In the above embodiment, a fourth inorganic film may be further provided, the fourth inorganic film being made of the inorganic material that constitutes the first inorganic film and being laminated on the other side of the second inorganic film. According to this embodiment, the water resistance of the protective layer can be further improved.

[0090] (13) In the above embodiment, the protective layer may be provided on the other side of the piezoelectric body in the second region. According to this embodiment, it is possible to prevent moisture from entering the piezoelectric body from the second region.

[0091] (14) In the above embodiment, the protective layer may not be provided on the other side of the piezoelectric body in the second region. According to this embodiment, the size of the protective layer in the extending direction can be reduced.

[0092] (15) According to a second aspect of the present disclosure, there is provided a liquid ejection device including the liquid ejection head of the first aspect and a control unit that controls an ejection operation to eject liquid from the liquid ejection head. According to this aspect, in the liquid ejection device, it is possible to reduce the possibility that the piezoelectric body will be burned near the end of the second electrode included in the liquid ejection head.

[0093] The present disclosure can also be realized in various forms other than liquid ejection devices and liquid ejection heads, for example, in the form of a method for manufacturing a liquid ejection head, a method for manufacturing a liquid ejection device, etc.

[0094] The present disclosure is not limited to inkjet systems, but can also be applied to any liquid ejection device that ejects liquid other than ink and the liquid ejection heads used in such liquid ejection devices. For example, the present disclosure can be applied to various liquid ejection devices and their liquid ejection heads, such as those listed below. (1) Image recording devices such as facsimile machines. (2) A color material ejection device used in the manufacture of color filters for image display devices such as liquid crystal displays. (3) Electrode material ejection equipment used to form electrodes for organic EL (Electro Luminescence) displays, surface-emitting displays (Field Emission Displays, FEDs), etc. (4) A liquid ejection device that ejects a liquid containing a bioorganic substance used in biochip manufacturing. (5) A sample dispensing device as a precision pipette. (6) Lubricating oil discharge device. (7) A resin liquid ejection device. (8) A liquid ejection device that ejects lubricating oil precisely onto precision machinery such as watches and cameras. (9) A liquid ejection device that ejects a transparent resin liquid, such as an ultraviolet curable resin liquid, onto a substrate to form minute hemispherical lenses (optical lenses) used in optical communication elements, etc. (10) A liquid ejection device that ejects an acidic or alkaline etching liquid for etching a substrate or the like. (11) A liquid ejection device having a liquid consuming head that ejects any other minute amount of liquid droplets.

[0095] A "liquid" can be any material that can be consumed by a liquid ejection device. For example, a "liquid" can be any material in a liquid phase, and includes materials with high or low viscosity, as well as liquid materials such as sols, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, and liquid metals (metal melts). Furthermore, not only liquids as a state of matter, but also particles of functional materials made of solids such as pigments and metal particles dissolved, dispersed, or mixed in a solvent are also included in the term "liquid." Representative examples of liquids include the following: (1) The main agent and hardener of adhesives. (2) Base paints and thinners, and clear paints and thinners. (3) A main solvent and a dilution solvent containing cells for the cell ink. (4) Metallic leaf pigment dispersion and dilution solvent for ink (metallic ink) that exhibits a metallic luster. (5) Gasoline, diesel and biofuels for vehicles. (6) The active ingredient and protective ingredient of a drug. (7) Phosphors and encapsulants for light-emitting diodes (LEDs). [Explanation of symbols]

[0096] 10...pressure chamber substrate, 12...pressure chamber, 13...throttle portion, 14...pressure chamber supply path, 15...communication plate, 16...nozzle communication path, 17...first manifold portion, 18...second manifold portion, 19...supply communication path, 20...nozzle plate, 21...nozzle, 30...sealing substrate, 30T...ceiling portion, 30W...wall portion, 31...holding portion, 32...through hole, 40...case member, 41...accommodating portion, 42...third manifold portion, 43...connection port, 44 ...supply port, 45...compliance substrate, 46...sealing film, 47...fixed substrate, 48...opening, 49...compliance portion, 50...diaphragm, 55...elastic film, 56...insulating film, 60...first electrode, 60b...one end portion, 70...piezoelectric body, 70b...one end portion, 80...second electrode, 80b...one end portion, 82, 82b, 82c, 82d, 82e...protective layer, 85...wiring portion, 91...first drive wiring, 92...second drive wiring, 92a...extension portion, 92b...extension portion, 100...manifold, 120...wiring board, 121...integrated circuit, 300...piezoelectric element, 500...liquid ejection device, 510...liquid ejection head, 550...ink tank, 552...tube, 560...transport mechanism, 562...transport roller, 564...transport rod, 566...transport motor, 570...movement mechanism, 572...carriage, 574...transport belt, 576...movement motor, 577...propeller Library, 580...controller, 821, 821b, 821c, 821d, 821e...first inorganic film, 822, 822b, 822c, 822d, 822e...second inorganic film, 823...third inorganic film, 824...fourth inorganic film, 825...fifth inorganic film, 826...sixth inorganic film, 827...seventh inorganic film, 828...eighth inorganic film, 829...ninth inorganic film, 830...tenth inorganic film, L1...first pressure chamber row, L2...second pressure chamber row, P...printing paper

Claims

1. A liquid ejection head, A piezoelectric body; a pressure chamber substrate on which a plurality of pressure chambers, each of which applies pressure to a liquid stored therein when the piezoelectric element is driven, are arranged in an arrangement direction that intersects with the extension direction of the pressure chambers; a first electrode provided on one side of the piezoelectric body in a stacking direction that is a direction intersecting the extension direction and the arrangement direction; a second electrode provided on the other side of the piezoelectric body in the stacking direction, which is opposite to the one side; a protective layer provided on the other side of the piezoelectric body in a boundary region that is a boundary between the first region and the second region in the extension direction, where a region in which the piezoelectric body and the second electrode overlap in the stacking direction is defined as a first region and a region in which the piezoelectric body is present but the second electrode is not present in the stacking direction is defined as a second region, The protective layer is a first inorganic film made of an inorganic material; a second inorganic film made of an inorganic material different from that of the first inorganic film, the first region and the pressure chamber overlap in the stacking direction; Liquid ejection head.

2. 2. The liquid ejection head according to claim 1, the first inorganic film is water resistant; The second inorganic film has insulating properties. Liquid ejection head.

3. 3. The liquid ejection head according to claim 2, the first inorganic film contains at least one of aluminum oxide, titanium oxide, tantalum oxide, and hafnium oxide; Liquid ejection head.

4. 3. The liquid ejection head according to claim 2, the second inorganic film contains at least one of silicon oxide, silicon nitride, and silicon carbide; Liquid ejection head.

5. 3. The liquid ejection head according to claim 2, the second inorganic film is laminated on the other side of the piezoelectric body, the first inorganic film is laminated on the other side of the second inorganic film; Liquid ejection head.

6. 6. The liquid ejection head according to claim 5, the second inorganic film has a thickness in the stacking direction greater than that of the first inorganic film; Liquid ejection head.

7. 6. The liquid ejection head according to claim 5, the second inorganic film has a thickness in the stacking direction that is smaller than that of the first inorganic film; Liquid ejection head.

8. 6. The liquid ejection head according to claim 5, a third inorganic film made of the inorganic material constituting the second inorganic film and laminated on the other side of the first inorganic film; Liquid ejection head.

9. 3. The liquid ejection head according to claim 2, the first inorganic film is laminated on the other side of the piezoelectric body, the second inorganic film is laminated on the other side of the first inorganic film; Liquid ejection head.

10. 10. The liquid ejection head according to claim 9, the second inorganic film has a thickness in the stacking direction that is smaller than that of the first inorganic film; Liquid ejection head.

11. 10. The liquid ejection head according to claim 9, the second inorganic film has a thickness in the stacking direction greater than that of the first inorganic film; Liquid ejection head.

12. 10. The liquid ejection head according to claim 9, a fourth inorganic film made of the inorganic material constituting the first inorganic film and laminated on the other side of the second inorganic film; Liquid ejection head.

13. 3. The liquid ejection head according to claim 1, the protective layer is provided on the other side of the piezoelectric body in the second region. Liquid ejection head.

14. 3. The liquid ejection head according to claim 1, the protective layer is not provided on the other side of the piezoelectric body in the second region; Liquid ejection head.

15. A liquid ejection device, A liquid ejection head according to any one of claims 1 to 12; a control unit that controls a discharge operation that causes the liquid to be discharged from the liquid discharge head, Liquid discharge device.

Images