Liquid discharge head and liquid discharge device

Abstract

To provide a liquid discharge head, which can suppress a crack from occurring while enhancing displacement characteristics.SOLUTION: In a liquid discharge head, a pressure chamber substrate provided with a plurality of pressure chambers, a vibration plate, a first electrode, a first thin film piezoelectric body, a second thin film piezoelectric body and a second electrode are laminated along a laminating direction in this order. Contents of lead contained in the liquid discharge head are 0.1 weight% or less. No other member is intervened between the first thin film piezoelectric body and the second thin film piezoelectric body. Young's modulus of the second thin film piezoelectric body is higher than Young's modulus of the first thin film piezoelectric body.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] A liquid ejection head is known that includes a piezoelectric actuator including a pressure chamber substrate having pressure chambers, a vibration plate that generates pressure in the pressure chambers, and a piezoelectric body formed on the vibration plate. Patent Document 1 discloses a liquid ejection head that includes a lead-free thin-film piezoelectric body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-155272 Summary of the Invention [Problem to be solved by the invention]

[0004] However, lead-free thin-film piezoelectric materials have poorer displacement characteristics than lead-based thin-film piezoelectric materials. Furthermore, lead-free thin-film piezoelectric materials have a larger stress difference between the diaphragm and the piezoelectric material than lead-based thin-film piezoelectric materials, which may cause cracks. Thus, lead-free thin-film piezoelectric materials have the problem of being unable to achieve both sufficient displacement characteristics and suppress cracks. [Means for solving the problem]

[0005] According to a first aspect of the present disclosure, there is provided a liquid ejection head, which includes a pressure chamber substrate having a plurality of pressure chambers, a vibration plate, a first electrode, a first thin-film piezoelectric body, a second thin-film piezoelectric body, and a second electrode stacked in this order along a stacking direction, the liquid ejection head contains 0.1 wt % or less of lead, no other member is interposed between the first thin-film piezoelectric body and the second thin-film piezoelectric body, and the second thin-film piezoelectric body has a higher Young's modulus than the first thin-film piezoelectric body.

[0006] According to a second aspect of the present disclosure, there is provided a liquid ejection device, comprising: the liquid ejection head of the first aspect; 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 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] FIG. 2 is a cross-sectional view schematically showing a detailed configuration of a piezoelectric element. [Figure 6] FIG. 2 is a cross-sectional view schematically showing the detailed configuration of a piezoelectric body. [Figure 7] FIG. 10 is a cross-sectional view schematically showing the detailed configuration of a piezoelectric body according to a second 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 83, the sealing substrate 30, the case member 40, and the like, 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 reference to Figure 5 as appropriate, along with Figures 3 and 4. Figure 5 is a cross-sectional view that schematically shows the detailed configuration of the piezoelectric element 300.

[0031] 5, 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] The first electrode 60 and the second electrode 80 are electrically connected to the wiring substrate 120 shown in FIGS. 3 and 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 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. Within the piezoelectric element 300, the first electrode 60 is provided in the +Z direction of the piezoelectric body 70, and the second electrode 80 is provided in the -Z direction. The portion 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 the active portion. Furthermore, the portion of the piezoelectric element 300 in which the first electrode 60 is not provided in the +Z direction of the piezoelectric body 70 and in which no piezoelectric distortion occurs in the piezoelectric body 70 even when a voltage is applied between the first electrode 60 and the second electrode 80 is also called the non-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. 5, 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 elongated along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. In this embodiment, the piezoelectric body 70 is formed as a thin film having a thickness of 5 μm or less. Examples of the piezoelectric body 70 include a perovskite-structured crystalline film made of a ferroelectric ceramic material exhibiting electromechanical transduction, which is formed on the first electrode 60, known as a perovskite crystal. In this embodiment, the piezoelectric body 70 is made of a composite oxide containing potassium, sodium, and niobium, more specifically, potassium sodium niobate ((K,Na)(NbO), abbreviated as "KNN"). As described above, the liquid ejection head 510 of this embodiment includes a lead-free piezoelectric body 70. In this embodiment, the liquid ejection head 510 including a lead-free piezoelectric body 70 refers to a liquid ejection head 510 configured so that the lead content in the liquid ejection head 510 is 0.1% by weight or less (preferably, a liquid ejection head that does not contain any lead). A more detailed structure of the piezoelectric body 70 will be described later. The material of the piezoelectric body 70 is not limited to the above materials, and may be, for example, bismuth ferrite ((BiFeO3), abbreviated as "BFO"), barium titanate ((BaTiO3), abbreviated as "BT"), potassium sodium lithium niobate ((K,Na,Li)(NbO3)), potassium sodium lithium niobate tantalate ((K,Na,Li)(Nb,Ta)O3), bismuth potassium titanate ((Bi1 / 2K1 / 2)TiO3, abbreviated as "BKT"), bismuth sodium titanate ((Bi1 / 2Na1 / 2)TiO3, abbreviated as "BNT"), bismuth manganate (BiMnO3, abbreviated as "BiMnO3"), or the like. or a composite oxide containing bismuth, potassium, titanium, and iron and having a perovskite structure (x[(BixK1-x)TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), a composite oxide containing bismuth, iron, barium, and titanium and having a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), or a composite oxide containing these with a metal such as manganese, cobalt, or chromium added ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (M is Mn, Co, or Cr)).

[0036] 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 is provided extending along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. As shown in FIG. 5, 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 such as platinum (Pt), iridium (Ir), gold (Au), or titanium (Ti), or a conductive metal oxide such as indium tin oxide (ITO). In this embodiment, iridium (Ir) is used for the second electrode 80.

[0037] 5, a protective layer 83 is formed on an end 80e on the −X direction side of the second electrode 80. The protective layer 83 is made of an organic material such as polyimide (aromatic polyimide) or an inorganic material such as aluminum oxide (Al2O3).

[0038] As shown in FIG. 5, a wiring portion 85 is provided on the −X-direction side of the −X-direction end portion 80e of the second electrode 80. The wiring portion 85 is not shown in FIG. 3. 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 70e of the piezoelectric body 70 to the −X-direction end portion 60e of the first electrode 60, with a gap between them and the end portion 80e of the second electrode 80. The −X-direction end portion 60e of the first electrode 60 extends further to the outside than the end portion 70e 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, 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. 5, the first drive wiring 91 is connected to the vicinity of the end 60e of the first electrode 60 via a wiring section 85, and is drawn out in the -X direction onto the vibration plate 50. The first drive wiring 91 is electrically connected to the end 60e of the first electrode 60 in the -X direction, which is drawn out further to the outside than the end 70e 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 the end 60e 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] Fig. 6 is a cross-sectional view schematically showing the detailed configuration of the piezoelectric body 70. Fig. 6 shows a portion of the cross section taken along line VI-VI in Fig. 3. In this embodiment, the piezoelectric body 70 has a first thin-film piezoelectric body 71 and a second thin-film piezoelectric body 72. As shown in Fig. 6, the pressure chamber substrate 10, the vibration plate 50, the first electrode 60, the first thin-film piezoelectric body 71, the second thin-film piezoelectric body 72, and the second electrode 80 are stacked in this order in the -Z direction of the stacking direction.

[0046] In this embodiment, first, the first thin-film piezoelectric element 71 is laminated by a sol-gel method, and then the second thin-film piezoelectric element 72 is laminated on the first thin-film piezoelectric element 71 by a sol-gel method. For example, the second thin-film piezoelectric element 72 is formed to have a higher density than the first thin-film piezoelectric element 71, thereby making the Young's modulus of the second thin-film piezoelectric element 72 higher than that of the first thin-film piezoelectric element 71. The first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 are laminated directly on each other without any intervening member. In this embodiment, in order to adjust the Young's moduli of the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 as described above, the thin-film piezoelectric elements are formed in two stages. After the first electrode 60 is formed and patterned on the vibration plate 50, a precursor solution for the first thin-film piezoelectric element 71 is applied and baked to crystallize the first thin-film piezoelectric element 71. Thereafter, a precursor solution for the second thin-film piezoelectric element 72 is separately applied and baked, and the second thin-film piezoelectric element 72 is crystallized on the first thin-film piezoelectric element 71. Thereafter, the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 are patterned, and the second electrode 80 is formed. The Young's moduli of the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 can be controlled by appropriately varying the baking time and baking temperature, the type and concentration of the precursor solution, the amount applied, etc. for the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72. For example, it has been found that the Young's moduli increase when the precursor solutions for the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 contain elements that are different from the main constituent elements of the respective thin-film piezoelectric elements. When the above-described KNN is used for the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72, their precursor solutions naturally contain K, Na, and Nb. However, if the precursor solution for the second thin-film piezoelectric body 72 contains more elements such as Mn than the precursor solution for the first thin-film piezoelectric body 71, the Young's modulus of the second thin-film piezoelectric body 72 can be made higher than that of the first thin-film piezoelectric body 71. It is also known that a higher firing temperature tends to increase the Young's modulus. Therefore, even if the precursor solutions for the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 are the same, the Young's modulus of the second thin-film piezoelectric body 72 can be made higher than that of the first thin-film piezoelectric body 71 by setting the firing temperature of the precursor solution for the first thin-film piezoelectric body 71 to a relatively low temperature of approximately 630°C and the firing temperature of the precursor solution for the second thin-film piezoelectric body 72 to a relatively high temperature of approximately 670°C.Here, one example of a method for controlling the Young's modulus of first thin film piezoelectric element 71 and second thin film piezoelectric element 72 has been shown, but it goes without saying that other methods of control may also be used.

[0047] The reason for configuring the piezoelectric body 70 of this embodiment as described above will be explained. Generally, lead-free piezoelectric bodies 70 have a higher tensile stress than lead-based piezoelectric bodies 70, which increases the stress difference between them and the diaphragm 50, potentially causing cracks. In order to prevent such cracks from occurring, the inventors attempted to reduce the Young's modulus of the piezoelectric body, in other words, to soften the piezoelectric body. This allowed the stress difference between the piezoelectric body and the diaphragm to be alleviated, thereby preventing cracks from occurring.

[0048] However, since the driving force of a piezoelectric body generally depends on the product of the piezoelectric constant, the Young's modulus, and the thickness of the piezoelectric body, reducing the Young's modulus of the entire piezoelectric body reduces the driving force of the piezoelectric body. Therefore, the inventors attempted to make the piezoelectric body 70 have a multi-layer structure of a first thin-film piezoelectric body 71 and a second thin-film piezoelectric body 72, as in this embodiment, and to make the Young's modulus of the second thin-film piezoelectric body 72, which is located farther from the diaphragm 50, greater than the Young's modulus of the first thin-film piezoelectric body 71, which is located closer to the diaphragm 50.

[0049] The diaphragm 50 is tensilely deformed by compressive deformation of the piezoelectric body 70. In this case, the point of force is located on the piezoelectric body 70 side, and the point of action is located on the diaphragm 50 side. The fulcrum is the neutral axis of the piezoelectric element 300 and the diaphragm 50. The neutral axis here refers to the position where the compressive stress and tensile stress of the piezoelectric element 300 and the diaphragm 50 are balanced. In this embodiment, the neutral axis is located slightly toward the +Z direction from the vicinity of the contact point between the piezoelectric body 70 and the diaphragm 50. Considering the moment of force, deformation at a position farther from the neutral axis, i.e., on the −Z direction side of the piezoelectric body 70, contributes more to the displacement of the diaphragm 50. In other words, increasing the Young's modulus of the second thin-film piezoelectric body 72 compared to the first thin-film piezoelectric body 71 can increase the displacement of the diaphragm 50 and improve the displacement characteristics of the entire piezoelectric body 70. On the other hand, the occurrence of cracks is suppressed by making the Young's modulus of the first thin-film piezoelectric element 71 in contact with the diaphragm 50 smaller than the Young's modulus of the second thin-film piezoelectric element 72. As described above, the piezoelectric element 70 of this embodiment can suppress the occurrence of cracks while improving the displacement characteristics.

[0050] In this embodiment, the Young's modulus of the second thin-film piezoelectric element 72 is set to be 1.3 to 2.1 times that of the first thin-film piezoelectric element 71. It is more desirable that the Young's modulus of the second thin-film piezoelectric element 72 be set to be 1.5 to 1.9 times that of the first thin-film piezoelectric element 71. A material with a low Young's modulus is formed with a low density and therefore has low electrical resistance. On the other hand, a material with a high Young's modulus is formed with a high density and therefore has high electrical resistance. In other words, when a voltage is applied to a piezoelectric element formed by stacking elements with significantly different Young's moduli, the element with the high Young's modulus and high electrical resistance bears most of the withstand voltage, which may result in an imbalance in the withstand voltage between the two stacked elements and damage to the piezoelectric element. By setting the ratio of the Young's modulus of the second thin-film piezoelectric element 72 to that of the first thin-film piezoelectric element 71 within the above-mentioned range, it is possible to prevent the withstand voltage balance between the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 from being lost, thereby preventing damage to the piezoelectric element 70.

[0051] According to the liquid ejection head 510 of the first embodiment described above, the Young's modulus of the second thin-film piezoelectric body 72 is greater than that of the first thin-film piezoelectric body 71, so the displacement characteristics of the piezoelectric body 70 can be improved. Furthermore, the Young's modulus of the first thin-film piezoelectric body 71 is smaller than that of the second thin-film piezoelectric body 72, so the stress difference between the piezoelectric body 70 and the vibration plate 50 can be alleviated, and the occurrence of cracks can be suppressed. In other words, the occurrence of cracks can be suppressed while the displacement characteristics are improved.

[0052] Furthermore, since the Young's modulus of the second thin-film piezoelectric element 72 is 1.3 to 2.1 times that of the first thin-film piezoelectric element 71, it is possible to prevent imbalance in the withstand voltages of the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72, and to prevent damage to the piezoelectric element 70.

[0053] B. Second embodiment: 7 is a cross-sectional view schematically showing the detailed configuration of a piezoelectric body 70b according to the second embodiment. The configuration of each part of the liquid ejection head 510 in the second embodiment other than the piezoelectric body 70b is the same as that in the first embodiment.

[0054] 7, the piezoelectric body 70b of the second embodiment is configured so that the second thin-film piezoelectric body 72b is thicker than the first thin-film piezoelectric body 71b. As described above, the driving force of a piezoelectric body depends on the product of the piezoelectric constant of the piezoelectric body, the Young's modulus of the piezoelectric body, and the thickness of the piezoelectric body. Therefore, by making the second thin-film piezoelectric body 72b thicker than the first thin-film piezoelectric body 71b, the displacement characteristics of the second thin-film piezoelectric body 72b located on the -Z direction side, which makes a greater contribution to the displacement of the diaphragm 50, can be increased, and the displacement characteristics of the piezoelectric body 70b can be further improved.

[0055] In this embodiment, the thickness of the second thin-film piezoelectric body 72b is set to be 1.5 to 2.5 times the thickness of the first thin-film piezoelectric body 71b. If the ratio of the thickness of the second thin-film piezoelectric body 72b to the thickness of the first thin-film piezoelectric body 71b becomes large, the thickness of the piezoelectric body 70b becomes excessive, which may increase the power required to drive the piezoelectric body 70b and the manufacturing cost of the liquid ejection head 510. By setting the ratio of the thickness of the second thin-film piezoelectric body 72b to the thickness of the first thin-film piezoelectric body 71b within the above range, it is possible to suppress such increases in power consumption and manufacturing cost.

[0056] According to the liquid ejection head 510 equipped with the piezoelectric body 70b of the second embodiment described above, the second thin-film piezoelectric body 72b is thicker than the first thin-film piezoelectric body 71b, and therefore the reduction in the displacement characteristics of the second thin-film piezoelectric body 72b located on the -Z direction side, which makes a greater contribution to the displacement of the vibration plate 50, can be made greater, thereby further improving the displacement characteristics of the piezoelectric body 70.

[0057] Furthermore, since the thickness of the second thin-film piezoelectric element 72b is 1.5 to 2.5 times the thickness of the first thin-film piezoelectric element 71b, the thickness of the piezoelectric element 70b can be prevented from becoming excessively large, and an increase in the power required to drive the piezoelectric element 70b and an increase in manufacturing costs can be prevented.

[0058] C. Third embodiment: The piezoelectric body 70 of the third embodiment differs from the piezoelectric body 70 of the first embodiment in that the piezoelectric constant of the second thin-film piezoelectric body 72 is greater than the piezoelectric constant of the first thin-film piezoelectric body 71. As described above, the driving force of a piezoelectric body depends on the product of the piezoelectric constant of the piezoelectric body, the Young's modulus of the piezoelectric body, and the thickness of the piezoelectric body. Therefore, in the liquid ejection head 510 including the piezoelectric body 70 of this embodiment, by making the piezoelectric constant of the second thin-film piezoelectric body 72 greater than the piezoelectric constant of the first thin-film piezoelectric body 71, the displacement characteristics of 72 located on the -Z direction side, which makes a greater contribution to the displacement of the diaphragm 50, can be increased, and the displacement characteristics of the piezoelectric body 70 can be further improved.

[0059] In this embodiment, the piezoelectric constant of the second thin film piezoelectric element 72 is set to be 1.1 to 1.3 times the piezoelectric constant of the first thin film piezoelectric element 71. This prevents the difference in displacement characteristics between the first thin film piezoelectric element 71 and the second thin film piezoelectric element 72 from becoming too large and damaging the piezoelectric element 70.

[0060] According to the liquid ejection head 510 equipped with the piezoelectric body 70 of the third embodiment described above, the piezoelectric constant of the second thin-film piezoelectric body 72 is higher than the piezoelectric constant of the first thin-film piezoelectric body 71, and therefore the displacement characteristics of the second thin-film piezoelectric body 72 located on the -Z direction side, which has a greater contribution to the displacement of the vibration plate 50, can be improved, and the displacement characteristics of the piezoelectric body 70 can be further improved.

[0061] Furthermore, since the piezoelectric constant of the second thin film piezoelectric element 72 is 1.1 to 1.3 times that of the first thin film piezoelectric element 71, it is possible to prevent the difference in displacement characteristics between the first thin film piezoelectric element 71 and the second thin film piezoelectric element 72 from becoming too large and damaging the piezoelectric element 70.

[0062] D. Other Embodiments: (D1) In the above embodiment, the piezoelectric body 70 is composed of two layers, the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72, but the present disclosure is not limited to this. The piezoelectric body 70 may be composed of three or more layers. In such a configuration, the Young's modulus of the layer located closer to the -Z direction among the multiple layers is configured to be higher than the Young's modulus of the layer located closer to the +Z direction. This configuration also achieves the same effects as the above embodiment.

[0063] (D2) In the above embodiment, the first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 are laminated by a sol-gel method, but the present disclosure is not limited to this. The first thin-film piezoelectric element 71 and the second thin-film piezoelectric element 72 may be laminated by any known film-forming technique, for example, sputtering. This configuration also achieves the same effects as the above embodiment.

[0064] E. Other forms: The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features of the embodiments corresponding to the technical features in each aspect described below can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0065] (1) According to a first aspect of the present disclosure, a liquid ejection head is provided. This liquid ejection head includes a pressure chamber substrate having a plurality of pressure chambers, a vibration plate, a first electrode, a first thin-film piezoelectric element, a second thin-film piezoelectric element, and a second electrode stacked in this order along a stacking direction. The liquid ejection head contains 0.1% or less lead by weight, no other components are interposed between the first and second thin-film piezoelectric elements, and the Young's modulus of the second thin-film piezoelectric element is higher than that of the first thin-film piezoelectric element. According to this aspect, the Young's modulus of the second thin-film piezoelectric element is higher than that of the first thin-film piezoelectric element, thereby suppressing a decrease in the displacement characteristics of the second thin-film piezoelectric element, which is located farther from the vibration plate in the stacking direction and contributes more to the vibration plate's displacement. This also suppresses a decrease in the displacement characteristics of the piezoelectric element. Furthermore, the Young's modulus of the first thin-film piezoelectric element is lower than that of the second thin-film piezoelectric element 72, thereby reducing the stress difference between the piezoelectric element and the vibration plate and suppressing the occurrence of cracks. In other words, the occurrence of cracks can be suppressed while improving the displacement characteristics.

[0066] (2) In the above embodiment, the Young's modulus of the second thin film piezoelectric material may be 1.3 to 2.1 times that of the first thin film piezoelectric material. This embodiment can prevent imbalance in withstand voltage between the first thin film piezoelectric material and the second thin film piezoelectric material, and can prevent damage to the piezoelectric material.

[0067] (3) In the above embodiment, the Young's modulus of the second thin film piezoelectric material may be 1.5 to 1.9 times that of the first thin film piezoelectric material. This embodiment can further prevent imbalance in withstand voltage between the first thin film piezoelectric material and the second thin film piezoelectric material, and can further prevent damage to the piezoelectric material.

[0068] (4) In the above embodiment, the second thin-film piezoelectric may be thicker than the first thin-film piezoelectric. With this embodiment, the second thin-film piezoelectric is thicker than the first thin-film piezoelectric, and therefore the second thin-film piezoelectric is located farther from the diaphragm in the stacking direction and has a greater contribution to the displacement of the diaphragm, so that the displacement characteristics of the piezoelectric body can be improved.

[0069] (5) In the above embodiment, the thickness of the second thin film piezoelectric element may be 1.5 to 2.5 times the thickness of the first thin film piezoelectric element. This embodiment prevents the piezoelectric element from becoming too thick, and also prevents increases in the power required to drive the piezoelectric element and increases in manufacturing costs.

[0070] (6) In the above embodiment, the piezoelectric constant of the second thin film piezoelectric material may be greater than the piezoelectric constant of the first thin film piezoelectric material. According to this embodiment, the displacement characteristics of the second thin film piezoelectric material, which is located farther from the diaphragm in the stacking direction and makes a greater contribution to the displacement of the diaphragm, can be increased, thereby further improving the displacement characteristics of the piezoelectric material.

[0071] (7) In the above embodiment, the piezoelectric constant of the second thin film piezoelectric element may be 1.1 to 1.3 times the piezoelectric constant of the first thin film piezoelectric element. This embodiment can prevent the piezoelectric elements from being damaged due to an excessive difference in displacement characteristics between the first and second thin film piezoelectric elements.

[0072] (8) In the above embodiment, the first and second thin-film piezoelectric elements may be formed of a composite oxide containing potassium, sodium, and niobium. According to this embodiment, in a liquid ejection head including the first and second thin-film piezoelectric elements formed of a composite oxide containing potassium, sodium, and niobium, it is possible to simultaneously suppress the deterioration of the displacement characteristics of the piezoelectric elements and the occurrence of cracks.

[0073] (9) According to a second aspect of the present disclosure, there is provided a liquid ejection device. This liquid ejection device includes the liquid ejection head according to any one of aspects 1 to 8, and a control unit that controls the ejection operation from the liquid ejection head. According to this aspect, in the liquid ejection device, the displacement characteristics of the piezoelectric body included in the liquid ejection head can be improved while also suppressing the occurrence of cracks.

[0074] 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.

[0075] 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.

[0076] 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, including 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 solid functional materials such as pigments and metal particles dissolved, dispersed, or mixed in a solvent can be 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]

[0077] 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...accommodation 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, 60e...end portion, 70, 70b...piezoelectric body, 70e...end portion, 71, 71b... First thin-film piezoelectric element, 72, 72b...second thin-film piezoelectric element, 80...second electrode, 80e...end portion, 83...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...pulley, 580...control unit, L1...first pressure chamber row, L2...second pressure chamber row, P...printing paper

Claims

1. A liquid ejection head, a pressure chamber substrate provided with a plurality of pressure chambers; A diaphragm and A first electrode; a first thin film piezoelectric body; a second thin film piezoelectric body; a second electrode, and The lead content of the liquid ejection head is 0.1% by weight or less, no other member is interposed between the first thin film piezoelectric element and the second thin film piezoelectric element; the Young's modulus of the second thin film piezoelectric body is higher than the Young's modulus of the first thin film piezoelectric body; Liquid ejection head.

2. 2. The liquid ejection head according to claim 1, the Young's modulus of the second thin film piezoelectric body is 1.3 to 2.1 times that of the first thin film piezoelectric body; Liquid ejection head.

3. 3. The liquid ejection head according to claim 2, the Young's modulus of the second thin film piezoelectric body is 1.5 to 1.9 times that of the first thin film piezoelectric body; Liquid ejection head.

4. 2. The liquid ejection head according to claim 1, the second thin film piezoelectric element is thicker than the first thin film piezoelectric element; Liquid ejection head.

5. 5. The liquid ejection head according to claim 4, the thickness of the second thin film piezoelectric element is 1.5 to 2.5 times the thickness of the first thin film piezoelectric element; Liquid ejection head.

6. 2. The liquid ejection head according to claim 1, the piezoelectric constant of the second thin film piezoelectric body is greater than the piezoelectric constant of the first thin film piezoelectric body; Liquid ejection head.

7. 7. The liquid ejection head according to claim 6, the piezoelectric constant of the second thin film piezoelectric body is 1.1 to 1.3 times the piezoelectric constant of the first thin film piezoelectric body; Liquid ejection head.

8. 2. The liquid ejection head according to claim 1, the first thin-film piezoelectric body and the second thin-film piezoelectric body are formed of a composite oxide containing potassium, sodium, and niobium; Liquid ejection head.

9. A liquid ejection device, The liquid ejection head according to any one of claims 1 to 8, a control unit for controlling a discharge operation from the liquid discharge head; Equipped with Liquid discharge device.

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