Liquid ejection head, liquid ejection apparatus, and piezoelectric element

Abstract

The invention relates to a liquid ejecting head, a liquid ejecting apparatus, and a piezoelectric element. In a liquid ejection head, generation of cracks is suppressed while displacement characteristics are improved. In the liquid ejection 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 stacked in this order in a stacking direction, and the content of lead contained in the liquid ejection head is 0.1 wt% or less. There is no other member between the first thin-film piezoelectric body and the second thin-film piezoelectric body, and 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.

Description

Technical Field

[0001] This disclosure relates to a liquid ejector head and a liquid ejection device. Background Technology

[0002] Liquid ejector heads equipped with piezoelectric actuators are known. These actuators include a pressure chamber substrate with a pressure chamber, a vibrating plate that generates pressure in the pressure chamber, and a piezoelectric element formed on the vibrating plate. Patent Document 1 discloses a liquid ejector head equipped with a non-lead-based thin-film piezoelectric element.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2011-155272

[0004] However, in non-lead thin-film piezoelectric materials, the displacement characteristics are reduced compared to lead-based thin-film piezoelectric materials. Furthermore, in non-lead thin-film piezoelectric materials, the stress difference between the vibrating plate and the piezoelectric material is greater than in lead-based materials, increasing the possibility of crack formation. Thus, in non-lead thin-film piezoelectric materials, there is a problem of not being able to simultaneously achieve sufficient displacement characteristics and suppress crack formation. Summary of the Invention

[0005] According to a first aspect of this disclosure, a liquid ejector head is provided. In this liquid ejector head, a pressure chamber substrate having multiple pressure chambers, a vibrating plate, a first electrode, a first thin-film piezoelectric element, a second thin-film piezoelectric element, and a second electrode are sequentially stacked along a stacking direction. The liquid ejector head contains less than 0.1% by weight of lead. There are no other components between the first and second thin-film piezoelectric elements. The Young's modulus of the second thin-film piezoelectric element is higher than that of the first thin-film piezoelectric element.

[0006] According to a second aspect of this disclosure, a liquid ejection device is provided. This liquid ejection device includes a liquid ejection head as described in the first aspect and a control unit for controlling the ejection action from the liquid ejection head. Attached Figure Description

[0007] Figure 1 This is an explanatory diagram showing the schematic configuration of the liquid ejection device in the first embodiment.

[0008] Figure 2 This is an exploded perspective view showing the structure of the liquid ejector head.

[0009] Figure 3 This is an explanatory diagram showing the structure of a liquid ejector head when viewed from above.

[0010] Figure 4 It is shown Figure 3 A cross-sectional view at position IV-IV.

[0011] Figure 5It is a schematic cross-sectional view showing the detailed structure of a piezoelectric element.

[0012] Figure 6 It is a schematic cross-sectional view showing the detailed structure of a piezoelectric material.

[0013] Figure 7 This is a cross-sectional view schematically showing the detailed structure of the piezoelectric element in the second embodiment.

[0014] Explanation of reference numerals in the attached figures

[0015] 10: Pressure chamber base plate, 12: Pressure chamber, 13: Throttling section, 14: Pressure chamber supply path, 15: Connecting plate, 16: Nozzle connecting path, 17: First manifold section, 18: Second manifold section, 19: Supply connecting path, 20: Nozzle plate, 21: Nozzle, 30: Sealing base plate, 30T: Top, 30W: Wall, 31: Holding section, 32: Through hole, 40: Housing component, 41: Receiving section, 42: Third manifold section, 43: Connection port, 44: Supply port, 45: Plastic base plate, 46: Sealing membrane, 47: Fixing base plate, 48: Opening, 49: Plastic section, 50: Vibrating plate, 55: Elastic membrane, 56: Insulating membrane, 60: First electrode, 60e: End, 70, 70b: Piezoelectric element, 70e: End, 71, 71b: First Thin film piezoelectric, 72, 72b: second thin film piezoelectric, 80: second electrode, 80e: end, 83: protective layer, 85: wiring section, 91: first drive wiring, 92: second drive wiring, 92a: extension setting section, 92b: extension setting section, 100: manifold, 120: wiring substrate, 121: integrated circuit, 300: piezoelectric element, 500: liquid ejection device, 510: liquid ejection head, 550: ink tank, 552: tube, 560: conveying mechanism, 562: conveying roller, 564: conveying rod, 566: conveying motor, 570: moving mechanism, 572: carriage, 574: conveyor belt, 576: moving motor, 577: pulley, 580: control section, L1: first pressure chamber row, L2: second pressure chamber row, P: printing paper. Detailed Implementation

[0016] A. First implementation method:

[0017] Figure 1 This is an explanatory diagram showing the schematic configuration of the liquid ejection device 500 in the 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. It should be noted that the liquid ejection device 500 can also replace the printing paper P with any type of medium such as resin film or cloth as the ink ejection target. Figure 1 as well as Figure 1The X, Y, and Z axes shown in 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 an orientation, a positive direction is designated as "+", and a negative direction as "-". When describing directions, positive and negative signs are used, with the direction the arrow points in each figure designated as the "+" direction and its opposite as the "-" direction. In this embodiment, the Z-axis direction is consistent with the vertical direction; the +Z direction represents vertically downward, and the -Z direction represents vertically upward. Furthermore, without limiting positive and negative directions, the three X, Y, and Z axes are described as the X-axis, Y-axis, and Z-axis, respectively.

[0018] The liquid ejection device 500 includes a liquid ejection head 510, an ink tank 550, a transport mechanism 560, a moving mechanism 570, and a control unit 580. Multiple nozzles are formed on the liquid ejection head 510, for example, ejecting four colors of ink—black, cyan, magenta, and yellow—into the +Z direction to form an image on printing paper P. The liquid ejection head 510 is mounted on a carriage 572 and reciprocates in the main scanning direction along with the movement of the carriage 572. In this embodiment, the main scanning direction is the +X and -X directions. The liquid ejection head 510 is not limited to ejecting four colors; it can also eject any ink such as light cyan, light magenta, transparent, and white.

[0019] The ink reservoir 550 contains the ink used to eject ink from the liquid ejector head 510. The ink reservoir 550 is connected to the liquid ejector head 510 via a resin tube 552. The ink in the ink reservoir 550 is supplied to the liquid ejector head 510 via the tube 552. It should be noted that a pouch-shaped liquid bag made of a flexible film can also be used instead of the ink reservoir 550.

[0020] The conveying mechanism 560 conveys the printing paper P in the secondary scanning direction. The secondary scanning direction is the direction that intersects the X-axis direction, which is the primary scanning direction; in this embodiment, it is the +Y and -Y directions. The conveying mechanism 560 includes a conveying rod 564 equipped with three conveying rollers 562 and a conveying motor 566 that drives the conveying rod 564 to rotate. By rotating the conveying rod 564, the conveying motor 566 conveys the printing paper P in the +Y direction, which is the secondary scanning direction. The number of conveying rollers 562 is not limited to three and can be any number. Furthermore, it is also possible to have a configuration with multiple conveying mechanisms 560.

[0021] The moving mechanism 570 includes a carriage 572, a conveyor belt 574, a moving motor 576, and pulleys 577. The carriage 572 is equipped with a liquid ejector head 510 capable of dispensing ink. The carriage 572 is fixed to the conveyor belt 574. The conveyor belt 574 is positioned between the moving motor 576 and the pulleys 577. Driven by the rotation of the moving motor 576, the conveyor belt 574 reciprocates in the main scanning direction. Consequently, the carriage 572, fixed to the conveyor belt 574, also reciprocates in the main scanning direction.

[0022] The control unit 580 is configured as a microcomputer with a CPU and a storage unit. The storage unit may be, for example, a non-volatile memory that can be erased by electrical signals, such as an EEPROM; a non-volatile memory that can be erased by ultraviolet light, such as a One-Time-PROM or EPROM; or a non-erasable non-volatile memory, such as a PROM. Various programs for implementing the functions provided in this embodiment are stored in the storage unit. The CPU centrally controls each part of the liquid dispensing device 500 by unfolding and executing the programs stored in the storage unit. The control unit 580 controls the reciprocating motion of the carriage 572 along the main scanning direction, the conveying motion of the printing paper P along the sub-scanning direction, and the dispensing motion of liquid from the liquid dispensing head 510.

[0023] Reference Figures 2 to 4 The detailed structure of the liquid ejector head 510 is explained below. Figure 2 This is an exploded perspective view showing the structure of the liquid ejector head 510. Figure 3 This is an explanatory diagram showing the configuration of the liquid ejector head 510 as viewed from above. In this disclosure, "viewed from above" means the state of the object observed along the stacking direction described later. Figure 3 The diagram shows the structure around the pressure chamber substrate 10 and the vibrating plate 50 in the liquid ejector head 510. For ease of understanding, the protective layer 83, sealing substrate 30, housing component 40, etc., are omitted from the illustration. Figure 4 It is shown Figure 3 A cross-sectional view at position IV-IV.

[0024] Liquid ejector head 510 has Figure 2 The pressure chamber substrate 10, connecting plate 15, nozzle plate 20, malleable substrate 45, vibrating plate 50, sealing substrate 30, housing component 40, wiring substrate 120, and the following components are shown. Figure 3The piezoelectric element 300 is shown. A liquid ejector head 510 is formed by stacking these stacked components. In this disclosure, the direction in which the stacked components forming the liquid ejector head 510 are stacked is also referred to as the "stack direction". In this embodiment, the stack direction is aligned with the Z-axis direction. In this disclosure, relative to a predetermined reference position, the +Z direction side is also referred to as "one side of the stack direction" or "lower side", and the -Z direction side is also referred to as "the other side of the stack direction" or "upper side".

[0025] The pressure chamber substrate 10 is formed, for example, using a silicon substrate, glass substrate, SOI substrate, or various ceramic substrates. Figure 3 As shown, a plurality of pressure chambers 12 are formed on the pressure chamber substrate 10. The ink channels formed on the pressure chamber substrate 10, including the pressure chambers 12, are formed by anisotropic etching of the pressure chamber substrate 10 from the +Z direction side. The pressure chambers 12 extend along the X-axis direction. Specifically, the pressure chambers 12 are formed into approximately rectangular shapes, where the length in the X-axis direction is longer than the length in the Y-axis direction when viewed from above. It should be noted that the shape of the pressure chambers 12 is not limited to a rectangle; it can also be a parallelogram, a polygon, an oblong shape, etc. An oblong shape refers to a shape based on a rectangle where the two ends of the long side are formed into semicircles, including rounded rectangles, ellipses, and eggs. In this disclosure, the X-axis direction is also referred to as the "extension direction".

[0026] like Figure 3 As shown, multiple pressure chambers 12 are arranged on the pressure chamber substrate 10 along a direction intersecting the extending direction. The direction in which the multiple pressure chambers 12 are arranged in a top view of the liquid ejector head 510 along the stacking direction is also referred to as the "arrangement direction." That is, the arrangement direction is the direction intersecting both the extending direction and the stacking direction. In this embodiment, the multiple pressure chambers 12 are arranged in two parallel rows, each with the Y-axis direction as its arrangement direction. Figure 3 In this example, two pressure chamber rows, a first pressure chamber row L1 and a second pressure chamber row L2, are formed on the pressure chamber substrate 10. The first pressure chamber row L1 has a first arrangement direction parallel to the Y-axis, and the second pressure chamber row L2 has a second arrangement direction parallel to the Y-axis. The first pressure chamber row L1 and the second pressure chamber row L2 are disposed on opposite sides of a wiring substrate 120. Specifically, the second pressure chamber row L2 is disposed on the opposite side of the first pressure chamber row L1 in the X-axis direction, which is the extending direction, separated by the wiring substrate 120. Figure 3 In the example, the second pressure chamber row L2 is disposed in the -X direction relative to the first pressure chamber row L1 across the wiring substrate 120. The multiple pressure chambers 12 do not necessarily all arrange themselves in a straight line; for example, they can be arranged in a so-called zigzag configuration along the Y-axis, with each pressure chamber 12 staggered in the intersecting direction.

[0027] like Figure 2 As shown, a connecting plate 15, a nozzle plate 20, and a malleable substrate 45 are stacked on the +Z direction side of the pressure chamber substrate 10. The connecting plate 15 is, for example, a flat plate made of a silicon substrate, glass substrate, SOI substrate, various ceramic substrates, metal substrates, etc. Examples of metal substrates include stainless steel substrates. A nozzle connecting path 16 and a first manifold portion 17 are provided on the connecting plate 15. Figure 4 The second manifold 18 and the supply connection path 19 are shown. The connection plate 15 is preferably made of a material with a thermal expansion coefficient that is approximately the same as that of the pressure chamber substrate 10. As a result, when the temperature of the pressure chamber substrate 10 and the connection plate 15 changes, warping of the pressure chamber substrate 10 and the connection plate 15 caused by the difference in thermal expansion coefficients can be suppressed.

[0028] like Figure 4 As shown, nozzle connection path 16 is a flow channel connecting pressure chamber 12 and nozzle 21. First manifold section 17 and second manifold section 18 function as part of manifold 100, which is a common liquid chamber connecting multiple pressure chambers 12. First manifold section 17 is configured to pass through connecting plate 15 in the Z-axis direction. Furthermore, as... Figure 4 As shown, the second manifold portion 18 does not penetrate the connecting plate 15 in the Z-axis direction, but is disposed on the surface of the connecting plate 15 in the +Z direction direction.

[0029] like Figure 4 As shown, the supply connection path 19 is a flow channel connected to the pressure chamber supply path 14 provided on the pressure chamber substrate 10. The pressure chamber supply path 14 is a flow channel connected to one end of the pressure chamber 12 in the X-axis direction via a throttling section 13. The throttling section 13 is a flow channel provided between the pressure chamber 12 and the pressure chamber supply path 14. The throttling section 13 is a flow channel whose inner wall protrudes from the pressure chamber 12 and the pressure chamber supply path 14 and is narrower than the pressure chamber 12 and the pressure chamber supply path 14. Therefore, the throttling section 13 has a higher flow resistance than the pressure chamber 12 and the pressure chamber supply path 14. With this configuration, even when pressure is applied to the pressure chamber 12 by the piezoelectric element 300 during ink ejection, it is possible to suppress or prevent the backflow of ink in the pressure chamber 12 to the pressure chamber supply path 14. There are multiple supply connection paths 19, arranged along the Y-axis direction, and each is individually provided for each pressure chamber 12. The supply path 19 and the pressure chamber supply path 14 connect the second manifold section 18 and each pressure chamber 12, supplying the ink in the manifold 100 to each pressure chamber 12.

[0030] The nozzle plate 20 is disposed on the side opposite to the pressure chamber substrate 10, i.e., on the +Z direction side of the connecting plate 15, separated by the connecting plate 15. There are no particular limitations on the material of the nozzle plate 20; for example, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, and metal substrates can be used. Examples of metal substrates include stainless steel substrates. Organic materials such as polyimide resin can also be used as the material of the nozzle plate 20. However, it is preferable to use a material with a coefficient of thermal expansion approximately the same as that of the connecting plate 15 for the nozzle plate 20. This suppresses warping of the nozzle plate 20 and the connecting plate 15 caused by differences in their coefficients of thermal expansion when the temperatures of the nozzle plate 20 and the connecting plate 15 change.

[0031] A plurality of nozzles 21 are formed on the nozzle plate 20. Each nozzle 21 is connected to a pressure chamber 12 via a nozzle connection path 16. Figure 2 As shown, multiple nozzles 21 are arranged along the Y-axis direction of the pressure chamber 12. Two rows of nozzles are provided on the nozzle plate 20, and the multiple nozzles 21 are arranged in rows within the nozzle rows. The two nozzle rows correspond to the first pressure chamber row L1 and the second pressure chamber row L2, respectively.

[0032] like Figure 4 As shown, the malleable substrate 45 and the nozzle plate 20 are disposed together on the side opposite to the pressure chamber substrate 10, i.e., on the +Z direction side of the connecting plate 15, separated by the connecting plate 15. The malleable substrate 45 is disposed around the nozzle plate 20, covering the openings of the first manifold portion 17 and the second manifold portion 18 disposed on the connecting plate 15. The malleable substrate 45 may include, for example, a sealing film 46 made of a flexible thin film, and a fixing substrate 47 made of a rigid material such as metal. Figure 4 As shown, an opening 48 is defined by completely removing the area in the fixed substrate 47 opposite to the manifold 100 in the thickness direction. Therefore, one side of the manifold 100 becomes a malleable part 49 sealed only by the sealing film 46.

[0033] like Figure 4 As shown, a vibrating plate 50 and a piezoelectric element 300 are stacked on the side opposite to the connecting plate 15, i.e., the -Z direction side of the pressure chamber substrate 10, separated from the pressure chamber substrate 10. The piezoelectric element 300 causes the vibrating plate 50 to flex and deform, thereby causing pressure changes in the ink within the pressure chamber 12. Figure 4 The diagram of the piezoelectric element 300 has been simplified.

[0034] A vibrating plate 50 is disposed between the piezoelectric element 300 and the pressure chamber substrate 10. The vibrating plate 50 includes: an elastic membrane 55 disposed closer to the pressure chamber substrate 10 than the piezoelectric element 300, and having silicon oxide (SiO2); and an insulating membrane 56 disposed on the elastic membrane 55, and having a zirconium oxide (ZrO2) film. The elastic membrane 55 forms the -Z direction side of the flow channels such as the pressure chamber 12. It should be noted that the vibrating plate 50 can be composed of either the elastic membrane 55 or the insulating membrane 56, and may also include other membranes besides the elastic membrane 55 and the insulating membrane 56. Examples of other membrane materials include silicon and silicon nitride.

[0035] like Figure 2 As shown, a sealing substrate 30 is also bonded to the -Z direction side of the pressure chamber substrate 10 by an adhesive or the like. This sealing substrate 30, when viewed from above, has approximately the same size as the pressure chamber substrate 10. Figure 4 As shown, the sealing substrate 30 includes a top 30T, a wall portion 30W, a holding portion 31, and a through hole 32. The holding portion 31 is a space defined by the top 30T and the wall portion 30W, which protects the active portion of the piezoelectric element 300 by accommodating it. In this embodiment, the holding portion 31 is provided for each row of piezoelectric elements 300, and 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. When viewed from above, the through hole 32 is disposed between the two holding portions 31 and is formed as an elongated rectangle along the Y-axis direction.

[0036] like Figure 4 As shown, a housing component 40 is fixed on the sealing base plate 30. The housing component 40 and the connecting plate 15 together form a manifold 100 communicating with a plurality of pressure chambers 12. When viewed from above, the housing component 40 has a substantially the same external shape as the connecting plate 15 and is joined in such a way that it covers the sealing base plate 30 and the connecting plate 15.

[0037] The housing component 40 has a receiving portion 41, a supply port 44, a third manifold portion 42, and a connection port 43. The receiving portion 41 is a space with a depth sufficient to accommodate the pressure chamber substrate 10, the vibrating plate 50, and the sealing substrate 30. The third manifold portion 42 is a space formed in the housing component 40 near both ends of the receiving portion 41 in the X-axis direction. The third manifold portion 42 is connected to the first manifold portion 17 and the second manifold portion 18 provided on the connecting plate 15 to form a manifold 100. The manifold 100 has an elongated shape in the Y-axis direction. The supply port 44 communicates with the manifold 100 to supply ink to each manifold 100. The connection port 43 is a through hole communicating with the through hole 32 of the sealing substrate 30, and the wiring substrate 120 is inserted into the connection port 43.

[0038] Liquid ejector head 510 from Figure 4 The supply port 44 shown is taken in from Figure 1 The ink supplied by the ink tank 550 fills the internal flow channels from the manifold 100 to the nozzle 21. A voltage based on a drive signal is then applied to each piezoelectric element 300 corresponding to the plurality of pressure chambers 12. This causes the vibrating plate 50 and the piezoelectric elements 300 to flex and deform together, changing the volume of each pressure chamber 12, increasing the internal pressure, and ejecting ink droplets from each nozzle 21.

[0039] and Figure 3 , Figure 4 Refer to them appropriately. Figure 5 The structure of the piezoelectric element 300 will be explained. Figure 5 This is a schematic cross-sectional view showing the detailed structure of the piezoelectric element 300.

[0040] like Figure 5 As shown, 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 sequentially in the -Z direction of the stacking direction. In the stacking direction, the piezoelectric body 70 is disposed between the first electrode 60 and the second electrode 80. The first electrode 60 is disposed on the +Z direction side of the piezoelectric body 70, and the second electrode 80 is disposed on the -Z direction side of the piezoelectric body 70.

[0041] The first electrode 60 and the second electrode 80 are connected via drive wiring. Figure 3 and Figure 4 The wiring substrate 120 shown is electrically connected. The driving wiring includes a first driving wiring 91 electrically connecting the wiring substrate 120 and the first electrode 60, and a second driving wiring 92 electrically connecting the wiring substrate 120 and the second electrode 80. The first electrode 60 and the second electrode 80 apply a voltage corresponding to the driving signal to the piezoelectric element 70. The driving voltage is the voltage applied to the piezoelectric element 300 by the control unit 580 from the first electrode 60 and the second electrode 80 to drive the piezoelectric element 300. The portion of the piezoelectric element 300 in which the first electrode 60 is provided in the +Z direction and the second electrode 80 is provided in the -Z direction, and which generates piezoelectric strain on the piezoelectric element 70 when a voltage is applied between the first electrode 60 and the second electrode 80, is also called an active portion. In addition, the portion of the piezoelectric element 300 in which the first electrode 60 is not provided in the +Z direction and which does not generate piezoelectric strain on the piezoelectric element 70 even when a voltage is applied between the first electrode 60 and the second electrode 80, is also called a passive portion.

[0042] A driving voltage varying according to the ink ejection rate is applied to the first electrode 60, while a predetermined reference voltage, independent of the ink ejection rate, is applied to the second electrode 80. When a voltage difference is generated between the first electrode 60 and the second electrode 80 by applying the driving voltage and the reference voltage, the piezoelectric element 70 of the piezoelectric element 300 deforms. This deformation of the piezoelectric element 70 causes the vibrating plate 50 to deform or vibrate, resulting in a change in the volume of the pressure chamber 12. This change in the volume of the pressure chamber 12 applies pressure to the ink contained within it, causing the ink to be ejected from the nozzle 21 via the nozzle connection path 16.

[0043] In this embodiment, the first electrode 60 is a separate electrode individually provided for each of the plurality of pressure chambers 12. For example... Figure 5 As shown, the first electrode 60 is a lower electrode disposed on the side opposite to the second electrode 80, i.e., below the piezoelectric body 70, separated from the piezoelectric body 70. The thickness of the first electrode 60 is, for example, about 80 nanometers. The first electrode 60 is formed of conductive materials such as metals like platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), or conductive metal oxides such as indium tin oxide (ITO). The first electrode 60 can also be formed by stacking various materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti). In this embodiment, platinum (Pt) is used as the first electrode 60.

[0044] like Figure 3As shown, the piezoelectric element 70 has a rectangular shape with a predetermined width in the X-axis direction and an elongated strip along the Y-axis direction, which is the arrangement direction of the pressure chambers 12. In this embodiment, the piezoelectric element 70 is formed as a thin film with a thickness of 5 μm or less. Examples of piezoelectric elements 70 include a perovskite-structured crystal film formed on the first electrode 60, which is composed of a ferroelectric ceramic material exhibiting an electromechanical conversion effect, or a so-called perovskite-type crystal. In this embodiment, the piezoelectric element 70 is constituted by a composite oxide containing potassium, sodium, and niobium, and more specifically, by potassium sodium niobate ((K, Na)(NbO3), abbreviated as "KNN"). Thus, the liquid nozzle 510 of this embodiment has a non-lead piezoelectric element 70. The liquid nozzle 510 with a non-lead piezoelectric element 70 described in this embodiment refers to a liquid nozzle 510 in which the lead content is 0.1% by weight or less (preferably a liquid nozzle that does not contain any lead at all). Further detailed structural information about piezoelectric element 70 will be described later. It should be noted that the material of piezoelectric element 70 is not limited to the materials mentioned above. For example, it can also be made of bismuth ferrite ((BiFeO3), abbreviated as "BFO"), barium titanate ((BaTiO3), abbreviated as "BT"), lithium potassium sodium niobate ((K, Na, Li)(NbO3)), lithium potassium sodium niobate tantalate ((K, Na, Li)(Nb, Ta)O3), potassium bismuth titanate ((Bi1 / 2K1 / 2)TiO3, abbreviated as "BKT"), sodium bismuth titanate ((Bi1 / 2Na1 / 2)TiO3, abbreviated as "BNT"), bismuth manganate (BiMnO3, abbreviated as "BNT"), etc. It consists of a composite oxide containing bismuth, potassium, titanium and iron with a perovskite structure (x[(BixK1-x)TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), a composite oxide containing bismuth, iron, barium and titanium with a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and a substance obtained by adding metals such as manganese, cobalt and chromium ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (M is Mn, Co or Cr)).

[0045] like Figure 3 As shown, the second electrode 80 is a universal electrode shared by multiple pressure chambers 12. The second electrode 80 is configured to have a predetermined width in the X-axis direction and extend along the arrangement direction of the pressure chambers 12, i.e., the Y-axis direction. Figure 5As shown, the second electrode 80 is an upper electrode disposed on the side opposite to the first electrode 60, i.e., above the piezoelectric body 70, separated from the piezoelectric body 70. The material of the second electrode 80 is the same as that of the first electrode 60, for example, a conductive material such as platinum (Pt), iridium (Ir), gold (Au), titanium (Ti), or a conductive metal oxide such as indium tin oxide (ITO). In this embodiment, iridium (Ir) is used as the second electrode 80.

[0046] like Figure 5 As shown, a protective layer 83 is formed at the end 80e on the -X direction side of the second electrode 80. The protective layer 83 is composed of organic materials such as polyimide (aromatic polyimide) and inorganic materials such as alumina (Al2O3).

[0047] like Figure 5 As shown, a wiring portion 85 is provided further along the -X direction than the -X direction end 80e of the second electrode 80. It should be noted that... Figure 3 The wiring portion 85 is omitted from the illustration. The wiring portion 85 is on the same layer as the second electrode 80, but is not electrically continuous with the second electrode 80. The wiring portion 85 is formed from the end 70e in the -X direction of the piezoelectric body 70 to the end 60e in the -X direction of the first electrode 60, spaced apart from the end 80e of the second electrode 80. The end 60e in the -X direction of the first electrode 60 is extended to a position further outward than the end 70e of the piezoelectric body 70. Multiple wiring portions 85 are provided for each piezoelectric element 300 and arranged at predetermined intervals along the Y-axis direction. Preferably, the wiring portion 85 is formed on 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 also be formed on a different layer than the second electrode 80.

[0048] like Figure 5 As shown, the first drive wiring 91 is electrically connected to the first electrode 60, which is a separate electrode, and the extension portions 92a and 92b of the second drive wiring 92 are electrically connected to the second electrode 80, which is a general-purpose electrode. The first drive wiring 91 and the second drive wiring 92 function as drive wiring for applying a voltage from the wiring substrate 120 to drive the piezoelectric element 70.

[0049] The first drive wiring 91 is configured individually for each first electrode 60. For example... Figure 5As shown, the first drive wiring 91 is connected to the vicinity of the end 60e of the first electrode 60 via the wiring portion 85, and is led out in the -X direction to the vibrating 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 led out to a position further out than the end 70e of the piezoelectric body 70. It should be noted that the wiring portion 85 may also be omitted, and the first drive wiring 91 may be directly connected to the end 60e of the first electrode 60.

[0050] like Figure 3 As shown, the second drive wiring 92 extends along the Y-axis direction and bends at both ends in the Y-axis direction to extend out along the X-axis direction. The second drive wiring 92 has an extension portion 92a and an extension portion 92b extending along the Y-axis direction. Figure 3 and Figure 4 As shown, the ends of the first drive wiring 91 and the second drive wiring 92 extend out of the through hole 32 of the sealing substrate 30 and are electrically connected to the wiring substrate 120 within the through hole 32.

[0051] The materials used for the first driving wiring 91 and the second driving wiring 92 are conductive materials, such as gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), and aluminum (Al). In this embodiment, gold (Au) is used for both the first driving wiring 91 and the second driving wiring 92. In this embodiment, the first driving wiring 91 and the second driving wiring 92 are formed by sputtering. It should be noted that the first driving wiring 91 and the second driving wiring 92 are not limited to sputtering and can be formed using any known film deposition technique.

[0052] The first drive wiring 91 and the second drive wiring 92 are formed on the same layer without being electrically continuous with each other. This allows the formation process of the first drive wiring 91 and the second drive wiring 92 to be generalized, simplifying the manufacturing process and preventing a decrease in the productivity of the liquid ejector head 510 compared to forming the first drive wiring 91 and the second drive wiring 92 separately. However, the first drive wiring 91 and the second drive wiring 92 can also be formed on different layers. The first drive wiring 91 and the second drive wiring 92 can also have a tightly adhering layer that improves the adhesion to the first electrode 60, the second electrode 80, and the vibrating plate 50.

[0053] The wiring substrate 120 is constructed, for example, using a flexible printed circuit (FPC). The wiring substrate 120 has multiple wirings for connection to the control unit 580 and a power supply circuit (not shown). It should be noted that an FPC can be used instead of an FFC (Flexible Flat Cable) or any other flexible substrate. An integrated circuit 121 having switching elements is mounted on the wiring substrate 120. The integrated circuit 121 is input with command signals for driving the piezoelectric element 300. Based on the command signals, the integrated circuit 121 controls the timing of supplying a drive signal for driving the piezoelectric element 300 to the first electrode 60.

[0054] Figure 6 This is a schematic cross-sectional view showing the detailed structure of the piezoelectric element 70. Figure 6 In, it is shown Figure 3 A portion of the cross-section at position VI-VI. In this embodiment, the piezoelectric element 70 has a first thin-film piezoelectric element 71 and a second thin-film piezoelectric element 72. As... Figure 6 As shown, a pressure chamber substrate 10, a vibrating plate 50, a first electrode 60, a first thin-film piezoelectric body 71, a second thin-film piezoelectric body 72, and a second electrode 80 are sequentially stacked in the -Z direction towards the stacking direction.

[0055] In this embodiment, firstly, a first thin-film piezoelectric body 71 is laminated using a sol-gel method, and then a second thin-film piezoelectric body 72 is laminated onto the first thin-film piezoelectric body 71 using the same method. The second thin-film piezoelectric body 72 is formed to have a higher density than the first thin-film piezoelectric body 71, thereby enabling the Young's modulus of the second thin-film piezoelectric body 72 to be higher than that of the first thin-film piezoelectric body 71. It should be noted that the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 are directly laminated without any other components separating them. In this embodiment, to adjust the Young's modulus of the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 as described above, the film formation of the thin-film piezoelectric bodies is performed in two stages. After the first electrode 60 is formed and patterned on the vibrating plate 50, a precursor solution of the first thin-film piezoelectric body 71 is coated and sintered to crystallize the first thin-film piezoelectric body 71. Subsequently, the precursor solution of the second thin-film piezoelectric body 72 is coated and fired separately, and the second thin-film piezoelectric body 72 is crystallized on the first thin-film piezoelectric body 71. Then, the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 are patterned, and the second electrode 80 is formed. By appropriately differentiating the firing time, firing temperature, type, concentration, and coating amount of the precursor solution for the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72, the Young's modulus of the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 can be controlled. For example, it is known that if the precursor solutions of the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 contain elements different from the main constituent elements of their respective thin-film piezoelectric bodies, the Young's modulus increases. When using KNN as the first thin-film piezoelectric material 71 and the second thin-film piezoelectric material 72, their respective precursor solutions naturally contain K, Na, and Nb. However, if the precursor solution of the second thin-film piezoelectric material 72 contains more elements such as Mn than the precursor solution of the first thin-film piezoelectric material 71, the Young's modulus of the second thin-film piezoelectric material 72 can be made larger than that of the first thin-film piezoelectric material 71. Furthermore, it is known that a higher firing temperature tends to increase the Young's modulus. Therefore, even if the precursor solutions of the first thin-film piezoelectric material 71 and the second thin-film piezoelectric material 72 are the same, the Young's modulus of the second thin-film piezoelectric material 72 can be made greater than that of the first thin-film piezoelectric material 71 by relatively lowering the firing temperature of the precursor solution of the first thin-film piezoelectric material 71 to about 630 degrees Celsius and relatively highering the firing temperature of the precursor solution of the second thin-film piezoelectric material 72 to about 670 degrees Celsius. Here, an example of a method for controlling the Young's modulus of the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 is shown. However, it is undeniable that other methods can also be used to control it.

[0056] The reasons for constructing the piezoelectric element 70 in this embodiment as described above will be explained. Generally, non-lead piezoelectric elements 70 experience greater tensile stress compared to lead-based piezoelectric elements 70. Therefore, the stress difference between the piezoelectric element and the vibrating plate 50 increases, potentially leading to cracking. To suppress the formation of these cracks, the inventors attempted to reduce the Young's modulus of the piezoelectric element; in other words, they attempted to make the piezoelectric element more flexible. This mitigates the stress difference between the piezoelectric element and the vibrating plate, thus suppressing crack formation.

[0057] However, in general, the driving force of a piezoelectric element depends on the product of its piezoelectric constant, Young's modulus, and thickness. Therefore, if the overall Young's modulus of the piezoelectric element is reduced, the driving force of the piezoelectric element decreases. Thus, the inventors attempted to form the piezoelectric element 70 as in this embodiment, with a multilayered structure of a first thin-film piezoelectric element 71 and a second thin-film piezoelectric element 72, such that the Young's modulus of the second thin-film piezoelectric element 72, located further from the vibrating plate 50, is greater than the Young's modulus of the first thin-film piezoelectric element 71, located closer to the vibrating plate 50.

[0058] The vibrating plate 50 undergoes tensile deformation due to the compressive deformation of the piezoelectric element 70. At this point, the force point can be considered to be on the piezoelectric element 70 side, while the point of application is on the vibrating plate 50 side. Furthermore, the fulcrum is the neutral axis of the piezoelectric element 300 and the vibrating plate 50. The neutral axis, as described here, is the position where the compressive and tensile stresses of the piezoelectric element 300 and the vibrating plate 50 are balanced. In this embodiment, the neutral axis is located slightly towards the +Z direction from the contact area between the piezoelectric element 70 and the vibrating plate 50. Considering the torque of the force, the deformation further from the neutral axis, i.e., on the -Z direction side of the piezoelectric element 70, has a greater impact on the displacement of the vibrating plate 50. In other words, making the Young's modulus of the second thin-film piezoelectric element 72 greater than that of the first thin-film piezoelectric element 71 increases the displacement of the vibrating plate 50, thereby improving the overall displacement characteristics of the piezoelectric element 70. On the other hand, by making the Young's modulus of the first thin-film piezoelectric element 71 in contact with the vibrating plate 50 smaller than that of the second thin-film piezoelectric element 72, crack generation is suppressed. As explained above, the piezoelectric element 70 according to this embodiment can suppress crack generation while improving displacement characteristics.

[0059] Furthermore, in this embodiment, the Young's modulus of the second thin-film piezoelectric body 72 is 1.3 to 2.1 times that of the first thin-film piezoelectric body 71. It should be noted that it is more desirable for the Young's modulus of the second thin-film piezoelectric body 72 to be 1.5 to 1.9 times that of the first thin-film piezoelectric body 71. Components with low Young's modulus are formed with high density and low resistance. On the other hand, components with high Young's modulus are formed with high density and high resistance. That is, when a voltage is applied to a piezoelectric body composed of stacked components with different Young's moduli, the component with high Young's modulus and high resistance bears most of the withstand voltage, potentially disrupting the voltage withstand balance between the two stacked components and damaging the piezoelectric body. By setting the ratio of the Young's modulus of the second thin-film piezoelectric 72 to the Young's modulus of the first thin-film piezoelectric 71 within the aforementioned range, it is possible to suppress the imbalance of the withstand voltage between the first thin-film piezoelectric 71 and the second thin-film piezoelectric 72, and to suppress damage to the piezoelectric 70.

[0060] According to the liquid ejector head 510 of the first embodiment described above, the Young's modulus of the second thin-film piezoelectric element 72 is greater than that of the first thin-film piezoelectric element 71, thus improving the displacement characteristics of the piezoelectric element 70. Furthermore, since the Young's modulus of the first thin-film piezoelectric element 71 is less than that of the second thin-film piezoelectric element 72, the stress difference between the piezoelectric element 70 and the vibrating plate 50 can be mitigated, suppressing crack formation. In other words, it is possible to improve displacement characteristics while simultaneously suppressing crack formation.

[0061] Furthermore, the Young's modulus of the second thin-film piezoelectric 72 is 1.3 to 2.1 times that of the first thin-film piezoelectric 71. Therefore, it can suppress the imbalance of the withstand voltage between the first thin-film piezoelectric 71 and the second thin-film piezoelectric 72, and can suppress damage to the piezoelectric 70.

[0062] B. Second implementation method:

[0063] Figure 7 This is a schematic cross-sectional view showing the detailed configuration of the piezoelectric element 70b in the second embodiment. The configuration of each part of the liquid ejector head 510 other than the piezoelectric element 70b in the second embodiment is the same as that in the first embodiment.

[0064] like Figure 7As shown, in the second embodiment, the piezoelectric body 70b is configured such 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 the piezoelectric body depends on the product of the piezoelectric constant, the Young's modulus, 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 has a greater influence on the displacement of the vibrating plate 50, can be improved, and the displacement characteristics of the piezoelectric body 70b can be further enhanced.

[0065] Furthermore, in this embodiment, the thickness of the second thin-film piezoelectric element 72b is configured to be 1.5 to 2.5 times the thickness of the first thin-film piezoelectric element 71b. If the ratio of the thickness of the second thin-film piezoelectric element 72b to the thickness of the first thin-film piezoelectric element 71b becomes large, the thickness of the piezoelectric element 70b becomes excessive, potentially increasing the power required to drive the piezoelectric element 70b and increasing the manufacturing cost of the liquid ejector head 510. By setting the ratio of the thickness of the second thin-film piezoelectric element 72b to the thickness of the first thin-film piezoelectric element 71b within the aforementioned range, the increase in related power consumption and manufacturing costs can be suppressed.

[0066] According to the liquid ejector head 510 of the second embodiment of the piezoelectric body 70b described above, the second thin-film piezoelectric body 72b is thicker than the first thin-film piezoelectric body 71b. Therefore, the displacement characteristics of the second thin-film piezoelectric body 72b, which is located on the -Z direction side that has a greater influence on the displacement of the vibrating plate 50, are higher, and the displacement characteristics of the piezoelectric body 70b can be further improved.

[0067] Furthermore, the thickness of the second thin-film piezoelectric 72b is 1.5 to 2.5 times that of the first thin-film piezoelectric 71b. Therefore, it is possible to prevent the thickness of the piezoelectric 70b from becoming too large, thereby preventing an increase in the power required to drive the piezoelectric 70b and an increase in manufacturing costs.

[0068] C. Third implementation method:

[0069] The piezoelectric element 70 of the third embodiment differs from that of the piezoelectric element 70 of the first embodiment in that the piezoelectric constant of the second thin-film piezoelectric element 72 is greater than that of the first thin-film piezoelectric element 71. As described above, the driving force of a piezoelectric element depends on the product of the piezoelectric constant, the Young's modulus, and the thickness of the piezoelectric element. Therefore, according to the liquid ejector head 510 equipped with the piezoelectric element 70 of this embodiment, by making the piezoelectric constant of the second thin-film piezoelectric element 72 greater than that of the first thin-film piezoelectric element 71, the displacement characteristics of the second thin-film piezoelectric element 72, located on the -Z direction side which has a greater influence on the displacement of the vibrating plate 50, can be improved, and the displacement characteristics of the piezoelectric element 70 can be further enhanced.

[0070] Furthermore, in this embodiment, the piezoelectric constant of the second thin-film piezoelectric body 72 is 1.1 to 1.3 times that of the first thin-film piezoelectric body 71. Therefore, it is possible to suppress the piezoelectric body 70 from being damaged by an excessively large difference in displacement characteristics between the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72.

[0071] According to the liquid ejector head 510 equipped with the piezoelectric body 70 described above, the piezoelectric constant of the second thin-film piezoelectric body 72 is higher than that of the first thin-film piezoelectric body 71. Therefore, the displacement characteristics of the second thin-film piezoelectric body 72, which is located on the -Z direction side that has a greater influence on the displacement of the vibrating plate 50, are improved, and the displacement characteristics of the piezoelectric body 70 are further improved.

[0072] Furthermore, the piezoelectric constant of the second thin-film piezoelectric body 72 is 1.1 to 1.3 times that of the first thin-film piezoelectric body 71. Therefore, it is possible to suppress the excessive difference in displacement characteristics between the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 from damaging the piezoelectric body 70.

[0073] D. Other implementation methods:

[0074] (D1) In the above embodiment, the piezoelectric body 70 is constructed using two layers: a first thin-film piezoelectric body 71 and a second thin-film piezoelectric body 72. However, this disclosure is not limited to this. The piezoelectric body 70 may also be constructed using three or more layers. In related embodiments, the Young's modulus of the layer located further in the -Z direction is higher than that of the layer located further in the +Z direction. According to the related embodiments, the same effect as in the above embodiment is achieved.

[0075] (D2) In the above embodiment, the first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 are stacked by a sol-gel method, but this disclosure is not limited to this. The first thin-film piezoelectric body 71 and the second thin-film piezoelectric body 72 can also be stacked by any known film-forming technique, such as sputtering. Depending on the relevant method, the same effect as the above embodiment can be achieved.

[0076] E. Other methods:

[0077] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, in order to solve some or all of the above-described technical problems, or to achieve some or all of the above-described effects, the technical features of the embodiments corresponding to the technical features in the aspects described below can be appropriately replaced or combined. Furthermore, technical features that are not described as essential technical features in this specification can be appropriately deleted.

[0078] (1) According to a first aspect of this disclosure, a liquid ejector head is provided. In this liquid ejector head, a pressure chamber substrate having multiple pressure chambers, a vibrating plate, a first electrode, a first thin-film piezoelectric, a second thin-film piezoelectric, and a second electrode are sequentially stacked along a stacking direction. The liquid ejector head contains less than 0.1% by weight of lead. There are no other components between the first thin-film piezoelectric and the second thin-film piezoelectric. The Young's modulus of the second thin-film piezoelectric is higher than that of the first thin-film piezoelectric. According to this aspect, since the Young's modulus of the second thin-film piezoelectric is higher than that of the first thin-film piezoelectric, the reduction in displacement characteristics of the second thin-film piezoelectric, which is located further away from the vibrating plate in the stacking direction and has a greater influence on the displacement of the vibrating plate, can be suppressed, and the reduction in the displacement characteristics of the piezoelectric can be suppressed. Furthermore, since the Young's modulus of the first thin-film piezoelectric is less than that of the second thin-film piezoelectric, the stress difference between the piezoelectric and the vibrating plate can be mitigated, and crack formation can be suppressed. That is, crack formation can be suppressed while improving displacement characteristics.

[0079] (2) In the above aspect, the Young's modulus of the second thin-film piezoelectric is also 1.3 to 2.1 times that of the first thin-film piezoelectric. According to this aspect, it is possible to suppress the breakdown of the voltage withstand balance between the first and second thin-film piezoelectrics and to suppress damage to the piezoelectric.

[0080] (3) In the above aspect, it is also possible that the Young's modulus of the second thin-film piezoelectric is 1.5 to 1.9 times that of the Young's modulus of the first thin-film piezoelectric. According to this aspect, it is possible to further suppress the disruption of the voltage withstand balance between the first and second thin-film piezoelectrics, and to further suppress damage to the piezoelectric.

[0081] (4) In the above aspect, it is also possible that the second thin-film piezoelectric body is thicker than the first thin-film piezoelectric body. According to this aspect, since the second thin-film piezoelectric body is thicker than the first thin-film piezoelectric body, the displacement characteristics of the second thin-film piezoelectric body, which is located further away from the vibrating plate in the stacking direction and has a greater influence on the displacement of the vibrating plate, are higher, and the displacement characteristics of the piezoelectric body can be further improved.

[0082] (5) In the above aspect, the thickness of the second thin-film piezoelectric body may also be 1.5 to 2.5 times the thickness of the first thin-film piezoelectric body. According to this aspect, it is possible to suppress the piezoelectric body thickness from becoming too large, and to suppress the increase in the power required to drive the piezoelectric body and the increase in manufacturing cost.

[0083] (6) In the above aspects, it is also possible that the piezoelectric constant of the second thin-film piezoelectric is greater than that of the first thin-film piezoelectric. According to this aspect, the displacement characteristics of the second thin-film piezoelectric, which is located further away from the vibrating plate in the stacking direction and has a greater influence on the displacement of the vibrating plate, are improved, and the displacement characteristics of the piezoelectric can be further enhanced.

[0084] (7) In the above aspect, the piezoelectric constant of the second thin-film piezoelectric body may also be 1.1 to 1.3 times that of the piezoelectric constant of the first thin-film piezoelectric body. According to this aspect, it is possible to suppress the piezoelectric body from being damaged by an excessive difference in displacement characteristics between the first and second thin-film piezoelectric bodies.

[0085] (8) In the above aspect, the first thin-film piezoelectric and the second thin-film piezoelectric may also be formed by a composite oxide comprising potassium, sodium, and niobium. According to this aspect, in a liquid ejector head having a first thin-film piezoelectric and a second thin-film piezoelectric formed by a composite oxide comprising potassium, sodium, and niobium, it is possible to both suppress the reduction of the displacement characteristics of the piezoelectric and suppress the generation of cracks.

[0086] (9) According to a second aspect of this disclosure, a liquid ejection device is provided. The liquid ejection device includes: a liquid ejection head as described in any one of aspects 1 to 8, and a control unit for controlling the ejection action from the liquid ejection head. According to this aspect, in the liquid ejection device, it is possible to improve the displacement characteristics of the piezoelectric element provided in the liquid ejection head while suppressing the generation of cracks.

[0087] This disclosure can also be implemented in various aspects other than liquid ejection devices and liquid ejection heads. For example, it can be implemented in methods for manufacturing liquid ejection heads and methods for manufacturing liquid ejection devices.

[0088] This disclosure is not limited to inkjet printing, but can also be applied to any liquid ejection device that ejects liquids other than ink, and to liquid ejection heads for such liquid ejection devices. For example, it can be applied to various liquid ejection devices and liquid ejection heads described below.

[0089] (1) Image recording devices such as fax machines.

[0090] (2) A color material ejection device for manufacturing color filters for image display devices such as liquid crystal displays.

[0091] (3) An electrode material ejection device for forming electrodes in organic EL (Electro Luminescence) displays, field emission displays (FEDs), etc.

[0092] (4) A liquid ejection device that ejects liquid containing organic matter from organisms used in the manufacture of biochips.

[0093] (5) Sample ejection device as a precision pipette.

[0094] (6) Lubricating oil spraying device.

[0095] (7) Resin liquid spraying device.

[0096] (8) A liquid spraying device that accurately sprays lubricating oil into precision machinery such as clocks and cameras.

[0097] (9) A liquid ejection device for spraying a transparent resin liquid, such as an ultraviolet-curable resin liquid, onto a substrate in order to form a small hemispherical lens (optical lens) for use in optical communication components.

[0098] (10) A liquid ejection device for ejecting acidic or alkaline etching solution for etching substrates, etc.

[0099] (11) Any other liquid ejection device having a liquid consumption head that ejects a small amount of liquid droplets.

[0100] The term "liquid" can simply refer to any material that can be consumed by a liquid ejection device. For example, "liquid" can refer to any material in its liquid phase state, including liquid 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 (molten metal). Furthermore, "liquid" includes not only liquids as a state of matter, but also substances obtained by dissolving, dispersing, or mixing functional material particles composed of solid substances such as pigments and metal particles in a solvent. Representative examples of liquids include the following.

[0101] (1) The main component and curing agent of the adhesive.

[0102] (2) Base coating and thinner, transparent coating and thinner.

[0103] (3) The main solvent and diluent of the cell containing cell ink.

[0104] (4) Metal foil pigment dispersion and diluent for inks that exhibit a metallic luster (metallic inks).

[0105] (5) Gasoline / diesel fuels and biofuels for vehicles.

[0106] (6) The main pharmaceutical components and protective components of the drug.

[0107] (7) Phosphor and sealing material of light-emitting diode (LED).

[0108] Furthermore, the present invention is not limited to piezoelectric elements for liquid ejection heads, but can also be widely applied to piezoelectric elements for other purposes, such as various sensors such as loudspeakers, ultrasonic motors, angle sensors and acceleration sensors, ferroelectric memories and ferroelectric capacitors.

Claims

1. A liquid ejector head, characterized in that, A pressure chamber substrate, a vibrating plate, a first electrode, a first thin-film piezoelectric element, a second thin-film piezoelectric element, and a second electrode, which are configured with multiple pressure chambers, are sequentially stacked along the stacking direction. The liquid nozzle contains less than 0.1% by weight of lead. There are no other components between the first thin-film piezoelectric body and the second thin-film piezoelectric body. The Young's modulus of the second thin-film piezoelectric is higher than that of the first thin-film piezoelectric.

2. The liquid ejector head according to claim 1, characterized in that, The Young's modulus of the second thin-film piezoelectric is 1.3 to 2.1 times that of the first thin-film piezoelectric.

3. The liquid ejector head according to claim 2, characterized in that, The Young's modulus of the second thin-film piezoelectric is 1.5 to 1.9 times that of the first thin-film piezoelectric.

4. The liquid ejector head according to claim 1, characterized in that, The second thin-film piezoelectric is thicker than the first thin-film piezoelectric.

5. The liquid ejector head according to claim 4, characterized in that, The thickness of the second thin-film piezoelectric is 1.5 to 2.5 times the thickness of the first thin-film piezoelectric.

6. The liquid ejector head according to claim 1, characterized in that, The piezoelectric constant of the second thin-film piezoelectric is greater than that of the first thin-film piezoelectric.

7. The liquid ejector head according to claim 6, characterized in that, The piezoelectric constant of the second thin-film piezoelectric is 1.1 to 1.3 times that of the piezoelectric constant of the first thin-film piezoelectric.

8. The liquid ejector head according to claim 1, characterized in that, The first and second thin-film piezoelectric bodies are formed by a composite oxide comprising potassium, sodium and niobium.

9. A liquid ejection device, characterized in that, have: The liquid ejector head according to any one of claims 1 to 8; and A control unit that controls the ejection action from the liquid nozzle.

10. A piezoelectric element, characterized in that, It comprises a first electrode, a first thin-film piezoelectric element, a second thin-film piezoelectric element, and a second electrode. The first electrode, the first thin-film piezoelectric, the second thin-film piezoelectric, and the second electrode are stacked sequentially along the stacking direction. The first and second thin-film piezoelectric bodies are formed by a composite oxide comprising potassium, sodium, and niobium. The Young's modulus of the second thin-film piezoelectric is higher than that of the first thin-film piezoelectric.

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