Liquid injection head, liquid injection device, and piezoelectric device

Abstract

To solve the problem that enough insulation properties cannot be obtained among electric wiring and there is a possibility for breakage to occur to a piezoelectric layer due to migration or the like.SOLUTION: In an active region A0 facing a pressure chamber 12, a diaphragm 50, a first electrode 60, a piezoelectric layer 70, and a second electrode 80 are layered from a pressure chamber substrate 10 side in this order. An area outside the active region A0 in a longitudinal direction of the pressure chamber 12 includes: a first area A1 where the piezoelectric layer 70, the second electrode 80, an insulation layer 150, and a first conductive layer 94(91) are layered from the pressure chamber substrate 10 side in this order; and a second area A2 where the piezoelectric layer 70 and the insulation layer 150 are layered from the pressure chamber substrate 10 side in this order and the second electrode 80 and the first conductive layer 94(91) are not layered.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a piezoelectric device including a first electrode, a piezoelectric layer, and a second electrode, a diaphragm that vibrates by driving the piezoelectric device, and a pressure chamber substrate that defines a pressure chamber that applies pressure to a liquid by vibration of the diaphragm, and a liquid injection head and a liquid injection device having the same, and also relates to a piezoelectric device having a piezoelectric element and a diaphragm.

Background Art

[0002] As a representative example of a liquid injection head, which is one type of piezoelectric device, an inkjet recording head that injects ink droplets can be mentioned. As an inkjet recording head, for example, it includes a pressure chamber substrate in which a pressure chamber communicating with a nozzle is formed, and a piezoelectric element provided via a diaphragm on one surface side of the pressure chamber substrate, and the piezoelectric element displaces the diaphragm to cause a pressure change in the ink in the pressure chamber, thereby injecting ink droplets from the nozzle.

[0003] As a piezoelectric element, one including a first electrode formed on a diaphragm, a piezoelectric layer formed of a piezoelectric material having electro-mechanical conversion characteristics on the first electrode, and a second electrode provided on the piezoelectric layer is known (see, for example, Patent Document 1).

[0004] Patent Document 1 discloses a configuration including a plurality of piezoelectric elements arranged in a row. Each piezoelectric element includes an active part (also referred to as an active portion) sandwiched between a first electrode, which is an individual electrode, and a second electrode, which is a common electrode, and in a direction orthogonal to the arrangement direction of the piezoelectric elements, the end of the active part is defined by the end of the second electrode.

[0005] In such a configuration where the end of the active part of the piezoelectric element is defined by the end of the second electrode, there is a risk of destruction such as burnout due to short circuit caused by migration or the like in the vicinity of the end of the active part. Further, when moisture enters the exposed portion of the piezoelectric layer, there is a risk that the piezoelectric layer will be destroyed in a relatively short time due to hydrolysis.

[0006] To resolve these problems, some piezoelectric elements have an adhesive layer that protects the area near the end of the active part of the piezoelectric element. Specifically, some piezoelectric elements have an exposed portion between a first wiring layer, which is wiring connected to the individual electrodes of the piezoelectric element, and a first metal layer, which is wiring connected to the common electrode of the piezoelectric element, and this exposed portion is covered with an adhesive layer (see Patent Document 2).

[0007] With this configuration, the wiring between which the piezoelectric layer is positioned, with the exposed portion in between, is insulated by the adhesive layer, thus suppressing the destruction of the piezoelectric layer due to migration or other factors. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2015-166160 [Patent Document 2] Japanese Patent Publication No. 2015-85668 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, in a configuration described in Patent Document 2, where adhesive is used to fill the gaps between wires corresponding to the exposed portion, air bubbles may remain because the adhesive is not sufficiently filled into the gaps between the wires. In this case, sufficient insulation may not be obtained between the wires, and there is a risk that the destruction of the piezoelectric layer due to migration or the like cannot be suppressed.

[0010] It should be noted that this problem is not limited to liquid ejection heads, such as those used in inkjet recording heads that eject ink, but also exists in other piezoelectric devices. [Means for solving the problem]

[0011] One aspect of the present invention that solves the above problems is a liquid spray head comprising a piezoelectric element including a first electrode, a piezoelectric layer and a second electrode, a first conductive layer electrically connected to the second electrode, an insulating layer formed of an insulating material, a diaphragm that vibrates by driving the piezoelectric element, and a pressure chamber substrate that partitions a pressure chamber that applies pressure to a liquid by the vibration of the diaphragm, wherein in the active region facing the pressure chamber, the diaphragm, the first electrode, the piezoelectric layer and the second electrode are stacked in this order from the pressure chamber substrate side, and the region outside the active region in the longitudinal direction of the pressure chamber includes a first region in which the piezoelectric layer, the second electrode, the insulating layer and the first conductive layer are stacked in this order from the pressure chamber substrate side, and a second region in which the piezoelectric layer and the insulating layer are stacked in this order from the pressure chamber substrate side, and the second electrode and the first conductive layer are not stacked.

[0012] Another aspect of the present invention is a liquid injection device characterized by comprising the liquid injection head of the above aspect.

[0013] Another aspect of the present invention is a piezoelectric device comprising a substrate having a recess, a diaphragm provided on one side of the substrate, a piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode, a first conductive layer electrically connected to the second electrode, and an insulating layer formed of an insulating material, wherein the diaphragm, the first electrode, the piezoelectric layer, and the second electrode are stacked in this order from the substrate side in an active region facing the recess, and the region outside the active region in the longitudinal direction of the recess includes a first region in which the piezoelectric layer, the second electrode, the insulating layer, and the first conductive layer are stacked in this order from the pressure chamber substrate side, and a second region in which the piezoelectric layer and the insulating layer are stacked in this order from the substrate side, and the second electrode and the first conductive layer are not stacked. [Brief explanation of the drawing]

[0014] [Figure 1] This is an exploded perspective view of the recording head according to Embodiment 1. [Figure 2]It is a plan view of a recording head according to Embodiment 1. [Figure 3] It is a cross-sectional view of a recording head according to Embodiment 1. [Figure 4] It is a cross-sectional view showing the overall configuration of a piezoelectric element according to Embodiment 1. [Figure 5] It is a cross-sectional view showing the main part of a piezoelectric element according to Embodiment 1. [Figure 6] It is a cross-sectional view showing the main part of a piezoelectric element according to Embodiment 1. [Figure 7] It is a cross-sectional view showing the main part of a piezoelectric element according to Embodiment 2. [Figure 8] It is a cross-sectional view showing the main part of a piezoelectric element according to Embodiment 3. [Figure 9] It is a cross-sectional view showing the main part of a piezoelectric element according to another embodiment. [Figure 10] It is a cross-sectional view showing the main part of a piezoelectric element according to another embodiment. [Figure 11] It is a diagram showing a schematic configuration of a recording apparatus according to an embodiment.

Mode for Carrying Out the Invention

[0015] Hereinafter, the present invention will be described in detail based on embodiments. However, the following description is an explanation of one aspect of the present invention, and the configuration of the present invention can be arbitrarily changed within the scope of the invention.

[0016] In each figure, X, Y, and Z represent three mutually orthogonal spatial axes. In this specification, the directions along these axes are referred to as the X direction, Y direction, and Z direction. The direction in which the arrow in each figure points is defined as the positive (+) direction, and the opposite direction of the arrow is defined as the negative (-) direction. Further, the Z direction indicates the vertical direction, the +Z direction indicates vertically downward, and the -Z direction indicates vertically upward. Furthermore, for the three X, Y, and Z spatial axes without limiting the positive and negative directions, they will be described as the X axis, Y axis, and Z axis.

[0017] (Embodiment 1) Figure 1 is an exploded perspective view of an inkjet recording head, which is an example of a liquid jet head in Embodiment 1 of the present invention. Figure 2 is a plan view of the recording head, and Figure 3 is a diagram illustrating the schematic configuration of the recording head, and is a cross-sectional view corresponding to line AA in Figure 2. Figure 4 is a cross-sectional view illustrating the overall configuration of the piezoelectric element. Figure 5 is a diagram illustrating the stacked structure in each region, and is an enlarged cross-sectional view of the vicinity of the end of the piezoelectric element in the X-axis direction. Figure 6 is a diagram illustrating the bonding state of the protective substrate, and is an enlarged cross-sectional view of the vicinity of the end of the piezoelectric element in the X-axis direction.

[0018] As shown in Figures 1 to 3, an inkjet recording head (hereinafter also simply referred to as a recording head) 1, which is an example of a liquid ejection head in this embodiment, ejects ink droplets in the first direction, the Z-axis direction, more specifically in the +Z direction.

[0019] The inkjet recording head 1 includes a pressure chamber substrate 10 as an example of a substrate. The pressure chamber substrate 10 is made of, for example, a silicon substrate, a glass substrate, an SOI substrate, or various ceramic substrates.

[0020] The pressure chamber substrate 10 has pressure chambers 12, which are recesses, arranged in two rows along the X-axis direction, intersecting the Z-axis direction. In other words, the pressure chamber substrate 10 has multiple pressure chambers 12 constituting each row, arranged along the Y-axis direction, intersecting the X-axis direction.

[0021] The multiple pressure chambers 12 constituting each row are arranged on a straight line along the Y-axis such that their positions in the X-axis direction are the same. Pressure chambers 12 adjacent to each other in the Y-axis direction are separated by a partition wall. Of course, the arrangement of the pressure chambers 12 is not particularly limited. For example, the arrangement of multiple pressure chambers 12 aligned in the Y-axis direction may be a so-called staggered arrangement, where each pressure chamber 12 is shifted by one in the X-axis direction.

[0022] Furthermore, the pressure chamber 12 in this embodiment is formed in a rectangular shape, for example, where the length in the X-axis direction is longer than the length in the Y-axis direction when viewed from the +Z direction in a plan view. Of course, the shape of the pressure chamber 12 when viewed from the +Z direction in a plan view is not particularly limited and may be a parallelogram, polygon, circle, oval, etc. Note that the oval shape referred to here is a shape based on a rectangle with semicircular ends in the longitudinal direction, and includes rounded rectangles, ellipses, egg shapes, etc.

[0023] On the +Z direction side of the pressure chamber substrate 10, the communication plate 15, the nozzle plate 20, and the compliance substrate 45 are sequentially stacked.

[0024] The communication plate 15 is provided with a nozzle communication passage 16 that connects the pressure chamber 12 and the nozzle 21. The communication plate 15 is also provided with a first manifold section 17 and a second manifold section 18 that constitute part of a manifold 100, which is a common liquid chamber through which multiple pressure chambers 12 are connected. The first manifold section 17 is provided penetrating the communication plate 15 in the Z-axis direction. The second manifold section 18 is provided opening on the +Z side surface without penetrating the communication plate 15 in the Z-axis direction.

[0025] Furthermore, the connecting plate 15 is provided with an independent supply passage 19 for each of the pressure chambers 12, which communicates with one end of the pressure chamber 12 in the X-axis direction. The supply passage 19 connects the second manifold section 18 to each pressure chamber 12, supplying ink from the manifold 100 to each pressure chamber 12.

[0026] As the connecting plate 15, a silicon substrate, glass substrate, SOI substrate, various ceramic substrates, metal substrates, etc., can be used. Examples of metal substrates include stainless steel substrates. It is preferable that the connecting plate 15 be made of a material with a coefficient of thermal expansion approximately the same as that of the pressure chamber substrate 10. This makes it possible to suppress warping of the pressure chamber substrate 10 and the connecting plate 15 caused by differences in their coefficients of thermal expansion when the temperatures of the pressure chamber substrate 10 and the connecting plate 15 change.

[0027] The nozzle plate 20 is provided on the side of the communication plate 15 opposite to the pressure chamber substrate 10, that is, on the +Z direction side. Nozzles 21 are formed on the nozzle plate 20, which communicate with each pressure chamber 12 via nozzle communication passages 16.

[0028] In this embodiment, the multiple nozzles 21 are arranged in a line along the Y-axis. The nozzle plate 20 has two rows of nozzles arranged in the X-axis direction, each row containing multiple nozzles 21. That is, the multiple nozzles 21 in each row are arranged so that they are at the same position in the X-axis direction. The arrangement of the nozzles 21 is not particularly limited. For example, the nozzles 21 arranged in a line along the Y-axis direction may be positioned with every other nozzle offset in the X-axis direction.

[0029] The material of the nozzle plate 20 is not particularly limited, but for example, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, and metal substrates can be used. Examples of metal plates include stainless steel substrates. Furthermore, 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 for the nozzle plate 20 that has approximately the same thermal expansion coefficient as the communication plate 15. This makes it possible to suppress warping of the nozzle plate 20 and the communication plate 15 caused by differences in thermal expansion coefficients when the temperature of the nozzle plate 20 and the communication plate 15 changes.

[0030] The compliance substrate 45 is provided together with the nozzle plate 20 on the side of the communication plate 15 opposite to the pressure chamber substrate 10, i.e., on the +Z direction side. This compliance substrate 45 is provided around the nozzle plate 20 and seals the openings of the first manifold section 17 and the second manifold section 18 provided on the communication plate 15. In this embodiment, the compliance substrate 45 comprises a sealing film 46 made of a flexible thin film and a fixed substrate 47 made of a hard material such as metal. The region of the fixed substrate 47 facing the manifold 100 is an opening 48 that is completely removed in the thickness direction. Therefore, one side of the manifold 100 is a compliance section 49 sealed only by the flexible sealing film 46.

[0031] On the other hand, on the side of the pressure chamber substrate 10 opposite to the nozzle plate 20, etc., that is, the side in the -Z direction, a diaphragm 50 and a piezoelectric element 300 that causes the diaphragm 50 to bend and deform, thereby generating a pressure change in the ink in the pressure chamber 12, are provided, as will be described in more detail later. Figure 3 is a diagram illustrating the overall configuration of the recording head 1, and the piezoelectric element 300 is shown in a simplified manner.

[0032] A protective substrate 30, having approximately the same size as the pressure chamber substrate 10, is further bonded to the -Z-direction side of the pressure chamber substrate 10. The protective substrate 30 has a holding portion 31, which is a space for protecting the piezoelectric elements 300. The holding portion 31 is provided independently for each row of piezoelectric elements 300 arranged in the Y-axis direction, and two of them are formed side by side in the X-axis direction. In addition, the protective substrate 30 has a through hole 32 that penetrates in the Z-axis direction between the two holding portions 31 arranged side by side in the X-axis direction.

[0033] Furthermore, a case member 40 is fixed to the protective substrate 30, which together defines a manifold 100 communicating with multiple pressure chambers 12, along with the pressure chamber substrate 10. The case member 40 has substantially the same shape as the aforementioned communication plate 15 in a plan view in the Z-axis direction, and is joined to the protective substrate 30 as well as to the aforementioned communication plate 15.

[0034] Such a case member 40 has a housing section 41 on the side of the protective substrate 30 that is a space with a depth capable of accommodating the pressure chamber substrate 10 and the protective substrate 30. This housing section 41 has an opening area larger than the surface of the protective substrate 30 that is joined to the pressure chamber substrate 10. When the pressure chamber substrate 10 and the protective substrate 30 are housed in the housing section 41, the opening surface of the housing section 41 on the nozzle plate 20 side is sealed by a communication plate 15.

[0035] Furthermore, the case member 40 has third manifold sections 42 defined on both outer sides of the housing section 41 in the X-axis direction. The manifold 100 of this embodiment is composed of the first manifold section 17 and the second manifold section 18 provided on the communication plate 15, and the third manifold section 42. The manifold 100 is provided continuously along the Y-axis direction, and the supply communication passages 19 that connect each pressure chamber 12 to the manifold 100 are arranged side by side in the Y-axis direction.

[0036] Furthermore, the case member 40 is provided with an inlet 44 that communicates with the manifold 100 and supplies ink to each manifold 100. In addition, the case member 40 is provided with a connection port 43 that communicates with the through hole 32 of the protective substrate 30 and through which the wiring board 120 is inserted.

[0037] In this embodiment of the recording head 1, ink is drawn in from an inlet 44 connected to an external ink supply means (not shown), and the inside is filled with ink from the manifold 100 to the nozzles 21. Then, according to the recording signal from the drive circuit 121, a voltage is applied to each piezoelectric element 300 corresponding to the pressure chamber 12. As a result, the diaphragm 50 bends and deforms together with the piezoelectric element 300, increasing the pressure in each pressure chamber 12, and ink droplets are ejected from each nozzle 21.

[0038] The configuration of the piezoelectric element 300 according to this embodiment will now be described. As described above, the piezoelectric element 300 is provided on the side of the pressure chamber substrate 10 opposite to the nozzle plate 20 via a diaphragm 50. That is, the recording head 1 comprises the pressure chamber substrate 10, the diaphragm 50 provided on the side of the pressure chamber substrate 10 in the -Z direction, and the piezoelectric element 300.

[0039] As shown in Figures 4 and 5, the diaphragm 50 is composed of an elastic film 51 made of silicon oxide provided on the pressure chamber substrate 10 side, and an insulating film 52 made of zirconium oxide provided on the elastic film 51. Liquid channels such as the pressure chamber 12 are formed by anisotropic etching of the pressure chamber substrate 10 from the +Z direction side, and the -Z direction side of the liquid channels such as the pressure chamber 12 is blocked by the elastic film 51.

[0040] Furthermore, the elastic film 51 can also be formed as a substrate integrated with the pressure chamber substrate 10. More specifically, for example, the pressure chamber substrate 10 can be formed from silicon, and a silicon oxide layer can be generated by thermal oxidation of its surface, and this silicon oxide layer can be used as the elastic film 51.

[0041] Furthermore, the composition of the diaphragm 50 is not particularly limited. The diaphragm 50 may be composed of either an elastic film 51 or an insulating film 52, or it may also include other films besides the elastic film 51 and the insulating film 52. Examples of materials for the other films include silicon and silicon nitride.

[0042] The piezoelectric element 300 is a pressure generating means that causes a pressure change in the ink in the pressure chamber 12 and is also called a piezoelectric actuator. This piezoelectric element 300 is composed of a first electrode 60, a piezoelectric body layer 70, and a second electrode 80, which are sequentially stacked from the +Z direction side (which is the diaphragm 50 side) toward the -Z direction.

[0043] Here, the portion of the piezoelectric element 300 in which piezoelectric strain occurs in the piezoelectric layer 70 when a voltage is applied between the first electrode 60 and the second electrode 80 is referred to as the active portion 310. In contrast, the portion of the piezoelectric layer 70 in which no piezoelectric strain occurs is referred to as the inactive portion 320. That is, the portion of the piezoelectric element 300 in which the piezoelectric layer 70 is sandwiched between the first electrode 60 and the second electrode 80 is the active portion 310, and the portion of the piezoelectric layer 70 not sandwiched between the first electrode 60 and the second electrode 80 is the inactive portion 320.

[0044] Furthermore, when the piezoelectric element 300 is driven, the part that actually displaces in the Z-axis direction is called the flexible part, and the part that does not displace in the Z-axis direction is called the non-flexible part. In other words, of the active part 310 of the piezoelectric element 300, the part facing the pressure chamber 12 in the Z-axis direction becomes the flexible part, and the part outside the pressure chamber 12 becomes the non-flexible part.

[0045] Generally, one of the electrodes of the active section 310 is configured as an individual electrode independent of each piezoelectric element 300, and the other electrode is configured as a common electrode common to multiple piezoelectric elements 300. In this embodiment, the first electrode 60 constitutes an individual electrode, and the second electrode 80 constitutes a common electrode.

[0046] The first electrode 60 is divided into individual electrodes for each pressure chamber 12, making each active portion 310 independent. The first electrode 60 is formed with a width narrower than the width of the pressure chamber 12 in the Y-axis direction. That is, both ends of the first electrode 60 in the Y-axis direction are located inside the region facing the pressure chamber 12.

[0047] Furthermore, in the X-axis direction, the first electrode 60 extends from the region facing the pressure chamber 12 to the outside of the pressure chamber 12. In the cross-sectional view of Figure 4, the -X end 60a and the +X end 60b of the first electrode 60 are located outside the pressure chamber 12. Specifically, the -X end 60a of the first electrode 60 is located in a position that is further in the -X direction than the -X end 12a of the pressure chamber 12, and the +X end 60b of the first electrode 60 is located in a position that is further in the +X direction than the +X end 12b of the pressure chamber 12.

[0048] The material of the first electrode 60 is not particularly limited, but conductive materials such as metals like iridium or platinum, or conductive metal oxides such as indium tin oxide (abbreviated as ITO) can be used.

[0049] The piezoelectric layer 70 is provided continuously along the Y-axis direction with a predetermined length in the X-axis direction. That is, the piezoelectric layer 70 is provided continuously along the direction in which the pressure chambers 12 are arranged side by side with a predetermined thickness. The thickness of the piezoelectric layer 70 is not particularly limited, but it is formed to a thickness of about 1 to 4 μm. Note that the piezoelectric layer 70 does not have to be continuous along the direction in which the pressure chambers 12 are arranged side by side. For example, notches may be provided in the piezoelectric layer 70 at each of the pressure chambers 12.

[0050] Furthermore, the length of the piezoelectric layer 70 in the X-axis direction is longer than the length of the pressure chamber 12 in the X-axis direction, and the piezoelectric layer 70 extends to both outer sides of the pressure chamber 12 in the X-axis direction. Also, the -X end 70a of the piezoelectric layer 70 in Figure 4 is located outside the -X end 60a of the first electrode 60. That is, the end 60a of the first electrode 60 is covered by the piezoelectric layer 70. On the other hand, the +X end 70b of the piezoelectric layer 70 is located inside the +X end 60b of the first electrode 60, i.e., towards the pressure chamber 12, and the end 60b of the first electrode 60 is not covered by the piezoelectric layer 70.

[0051] Examples of piezoelectric layers 70 include perovskite-structured crystalline films (perovskite-type crystals) made of ferroelectric ceramic material exhibiting electromechanical conversion properties, formed on the first electrode 60. For example, the material for the piezoelectric layer 70 can be a ferroelectric piezoelectric material such as lead zirconate titanate (PZT), or a material to which metal oxides such as niobium oxide, nickel oxide, or magnesium oxide are added. Specifically, lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead zirconate titanate lanthanum ((Pb,La)(Zr,Ti)O3), or magnesium zirconium titanate lead (Pb(Zr,Ti)(Mg,Nb)O3). In this embodiment, lead zirconate titanate (PZT) was used as the piezoelectric layer 70.

[0052] Furthermore, the material for the piezoelectric layer 70 is not limited to lead-based piezoelectric materials containing lead; lead-free piezoelectric materials can also be used. Examples of lead-free piezoelectric materials include bismuth ironate ((BiFeO3), abbreviated as "BFO"), barium titanate ((BaTiO3), abbreviated as "BT"), potassium sodium niobate ((K,Na)(NbO3), abbreviated as "KNN"), potassium sodium lithium niobate ((K,Na,Li)(NbO3)), potassium sodium lithium tantalate niobate ((K,Na,Li)(Nb,Ta)O3), and potassium bismuth titanate ((Bi 1 / 2 K 1 / 2 )TiO3, abbreviated as "BKT"), bismuth sodium titanate ((Bi 1 / 2 Na 1 / 2 (x[(Bi x K 1-x((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BKT-BF"), a composite oxide having a perovskite structure containing bismuth, iron, barium, and titanium ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and those to which metals such as manganese, cobalt, and chromium are added ((1-x)[Bi(Fe 1-y M y Examples include )O3]-x[BaTiO3](where M is Mn, Co, or Cr).

[0053] The second electrode 80 is provided on the -Z direction side of the piezoelectric layer 70, opposite to the first electrode 60, and constitutes a common electrode common to multiple piezoelectric elements 300. The second electrode 80 is provided continuously in the Y direction with a predetermined length in the X direction.

[0054] Furthermore, in Figure 4, the -X end 80a of the second electrode 80 is positioned outside the end 60a of the first electrode 60, which is covered by the piezoelectric layer 70. That is, the end 80a of the second electrode 80 is located outside the -X end 12a of the pressure chamber 12 and outside the end 60a of the first electrode 60. Therefore, the -X end of the active portion 310, i.e., the boundary between the active portion 310 and the inactive portion 320, is defined by the end 60a of the first electrode 60.

[0055] On the other hand, in Figure 4, the +X end 80b of the second electrode 80 is located outside the +X end 12b of the pressure chamber 12, but inside the +X end 70b of the piezoelectric layer 70. As described above, the end 70b of the piezoelectric layer 70 is located inside the end 60b of the first electrode 60. Therefore, the end 80b of the second electrode 80 is located on the piezoelectric layer 70 inside the end 60b of the first electrode 60.

[0056] Thus, since the end 80b of the second electrode 80 is positioned in the -X direction more than the +X direction ends 60b, 70b of the piezoelectric layer 70 and the first electrode 60, the +X direction end of the active portion 310, i.e., the boundary between the active portion 310 and the inactive portion 320, is defined by the end 80b of the second electrode 80. Furthermore, outside the end 80b of the second electrode 80, there is an exposed portion 71 where the surface of the piezoelectric layer 70 is exposed.

[0057] The material of the second electrode 80 is not particularly limited, but, similar to the first electrode 60, conductive materials such as metals like iridium or platinum, or conductive metal oxides such as indium tin oxide are preferably used.

[0058] Furthermore, outside the end 80b of the second electrode 80, that is, in the +X direction further from the end 80b of the second electrode 80, there is a wiring layer 85 which is made of the same layer as the second electrode 80 but is electrically discontinuous with the second electrode 80.

[0059] This wiring layer 85 is formed on the piezoelectric layer 70 and extends over the first electrode 60, which is located further in the +X direction than the piezoelectric layer 70, with a gap between them so as not to come into contact with the end portion 80b of the second electrode 80. Furthermore, the wiring layer 85 is provided independently for each active portion 310. In other words, multiple wiring layers 85 are arranged at predetermined intervals in the Y-axis direction.

[0060] As described above, the piezoelectric layer 70 constituting the piezoelectric element 300 has a second electrode 80 and a wiring layer 85 spaced apart in the X-axis direction. The surface of the piezoelectric layer 70 is exposed in the gap between the second electrode 80 and the wiring layer 85. In other words, the portion of the piezoelectric layer 70 constituting the piezoelectric element 300 between the second electrode 80 and the wiring layer 85 is an exposed portion 71, on the side opposite to the pressure chamber substrate 10, which is exposed from the second electrode 80 and the wiring layer 85.

[0061] Here, the thickness d1 of the piezoelectric layer 70 in the exposed portion 71 is thinner than the thickness d2 of the piezoelectric layer 70 in other parts (see Figure 5). In other words, a recess 72 is formed in the exposed portion 71 of the piezoelectric layer 70 where a thin layer of the surface has been removed.

[0062] The exposed portion 71 of the piezoelectric layer 70 is covered by an insulating layer 150 made of an insulating material. The insulating layer 150 is continuously provided in the X-axis direction from above the second electrode 80 to above the wiring layer 85. In other words, the insulating layer 150 is provided to cover the end 80b of the second electrode 80 and the -X-direction end 85a of the wiring layer 85, as shown in Figure 4, together with the exposed portion 71 of the piezoelectric layer 70. To put it another way, the insulating layer 150 is formed to overlap the end 80b of the second electrode 80 and the end 85a of the wiring layer 85 in the X-axis direction.

[0063] The insulating layer 150 is provided continuously over regions corresponding to multiple piezoelectric elements 300 in the Y-axis direction. This makes it easier to improve moisture barrier properties. However, the insulating layer 150 only needs to cover at least the portion of the exposed part 71 of the piezoelectric layer 70 sandwiched between the second electrode 80 and the wiring layer 85, and may be provided independently for each piezoelectric element 300.

[0064] The material of the insulating layer 150 is not particularly limited as long as it has electrical insulating properties and moisture barrier properties, but for example, a photosensitive resin such as polyimide can be used. When a photosensitive resin is used, the insulating layer 150 is formed by photolithography after heat treatment following the formation of the second electrode 80. Alternatively, an inorganic insulating material such as aluminum oxide may be used as the material of the insulating layer 150. In this case, for example, the insulating layer 150 can be formed over the entire surface by sputtering via a mask, and then lifted off to form the insulating layer 150 only in the desired area.

[0065] Furthermore, a common lead electrode 91, which is the first conductive layer, is connected to the second electrode 80 that constitutes the piezoelectric element 300. Also, individual lead electrodes 92, which are the second conductive layer, are connected to the first electrode 60 that constitutes the piezoelectric element 300. A flexible wiring board 120 is connected to the ends of the common lead electrode 91 and the individual lead electrodes 92 that are opposite to the ends connected to the piezoelectric element 300.

[0066] In this embodiment, the common lead electrode 91 and the individual lead electrodes 92 extend so as to be exposed within a through hole 32 formed in the protective substrate 30, and are electrically connected to the wiring board 120 within this through hole 32. A drive circuit 121 having a switching element for driving the piezoelectric element 300 is mounted on the wiring board 120.

[0067] The material of the common lead electrode 91 and the individual lead electrodes 92 is not particularly limited as long as it is a conductive material, and for example, gold (Au), platinum (Pt), aluminum (Al), copper (Cu), etc. can be used. In this embodiment, gold (Au) was used for the common lead electrode 91 and the individual lead electrodes 92. The common lead electrode 91 and the individual lead electrodes 92 may also be configured to include an adhesion layer made of nickel-chromium (NiCr) or the like to improve adhesion with the first electrode 60, the second electrode 80 and the diaphragm 50.

[0068] The thickness d3 of the common lead electrode 91 is not particularly limited, but in this embodiment, it is thicker than the thickness d4 of the second electrode 80 to which the common lead electrode 91 is connected (see Figure 5). Similarly, the thickness d5 of the individual lead electrode 92 is not particularly limited, but in this embodiment, it is thicker than the thickness d6 of the wiring layer 85 to which the individual lead electrode 92 is connected.

[0069] The common lead electrode 91 is drawn out in the X-axis direction from the second electrode 80, which constitutes the common electrode on the piezoelectric layer 70, to the diaphragm 50 at both ends in the Y-axis direction. The common lead electrode 91, which is the first conductive layer, also has a first auxiliary wiring section 93 that extends along the Y-axis direction near the -X end 12a of the pressure chamber 12 in Figure 4. Furthermore, the common lead electrode 91 has a second auxiliary wiring section 94 that extends along the Y-axis direction in a region corresponding to the +X end 12b of the pressure chamber 12. These first auxiliary wiring sections 93 and second auxiliary wiring sections 94 are provided continuously along the Y-axis direction for multiple piezoelectric elements 300.

[0070] Here, because the second electrode 80 is formed thinly, it has high electrical resistance, and the charge distribution is prone to becoming uneven. Therefore, by providing a first auxiliary wiring section 93 and a second auxiliary wiring section 94 with relatively low electrical resistance on the second electrode 80, the unevenness in the charge distribution is suppressed. This makes it possible to suppress variations in the amount of displacement when driving multiple piezoelectric elements 300.

[0071] Furthermore, the second auxiliary wiring portion 94 of the common lead electrode 91 is located outside the pressure chamber 12 in the X-axis direction. In this embodiment, the active portion 310 of the piezoelectric element 300 extends to the outside of the pressure chamber 12 at both ends of the pressure chamber 12 in the X-axis direction, and the second auxiliary wiring portion 94 extends over this active portion 310, i.e., over the second electrode 80, to the insulating layer 150. For example, in Figure 4, the -X end 94a of the second auxiliary wiring portion 94 is located near the end 12b of the pressure chamber 12, and the +X end 94b is located on the insulating layer 150. The end 94a of the second auxiliary wiring portion 94 may also be located inside the pressure chamber 12.

[0072] On the other hand, individual lead electrodes 92 are provided independently for each piezoelectric element 300, that is, for each first electrode 60. In Figure 4, the individual lead electrodes 92 are connected via a wiring layer 85 to the vicinity of the +X end 60b of the first electrode 60, which extends to the outside of the piezoelectric layer 70, and one end of the individual lead electrode 92 is drawn out in the X-axis direction onto the pressure chamber substrate 10, and actually onto the diaphragm 50. The other end of the individual lead electrode 92 extends in the X-axis direction to the insulating layer 150. For example, in Figure 4, the -X end 92a of the individual lead electrode 92 is located on the insulating layer 150, and the +X end 92b is located on the diaphragm 50.

[0073] Furthermore, since the common lead electrode 91 and the individual lead electrodes 92 extend onto the insulating layer 150, if a photosensitive resin is used as the material for the insulating layer 150, it is preferable to form them by electroless plating, for example. This is because if the common lead electrode 91 and the individual lead electrodes 92 are formed by electrolytic plating, the insulating layer 150 may be damaged.

[0074] As described above, on the -Z direction side of the pressure chamber substrate 10, the diaphragm 50, the first electrode 60, the piezoelectric layer 70 and the second electrode 80 constituting the piezoelectric element 300, the common lead electrode 91 (second auxiliary wiring section 94) which is the first conductive layer, the individual lead electrodes 92 which is the second conductive layer, and the insulating layer 150 are stacked in a predetermined order for each region.

[0075] More specifically, as shown in Figure 5, in the active region A0 facing the pressure chamber 12, the diaphragm 50, the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are stacked in this order from the pressure chamber substrate 10 side. Furthermore, the region outside the active region A0 in the X-axis direction, which is the longitudinal direction of the pressure chamber 12, for example, the region on the +X side of the active region A0, includes the first region A1, the second region A2, the third region A3, the fourth region A4, and the fifth region A5.

[0076] The first region A1 is a region in which the diaphragm 50, the first electrode 60, the piezoelectric layer 70, the second electrode 80, the insulating layer 150, and the second auxiliary wiring section 94 (91), which is the first conductive layer, are stacked in this order from the pressure chamber substrate 10 side.

[0077] In this embodiment, the first region A1 includes the diaphragm 50 and the first electrode 60, but it is not essential that these be included. The first region A1 may not include at least one of the diaphragm 50 and the first electrode 60. Furthermore, in the first region A1, it is preferable that the insulating layer 150 is thicker than the second electrode 80 and that the second auxiliary wiring portion 94(91) is thicker than the insulating layer 150.

[0078] The second region A2 is the region in which the diaphragm 50, the first electrode 60, the piezoelectric layer 70, and the insulating layer 150 are laminated in this order from the pressure chamber substrate 10 side, and the second electrode 80 and the second auxiliary wiring section 94(91) are not laminated. In this embodiment, the second region A2 is the region corresponding to the exposed portion 71 of the piezoelectric layer 70, and is located on the opposite side of the first region A1 from the pressure chamber 12. In other words, the first region A1 is the region on the pressure chamber 12 side of the second region A2, for example, the region adjacent to the second region A2 in the -X direction in Figure 5. In this embodiment, the second region A2 includes the diaphragm 50 and the first electrode 60, but it is not essential that they be included. The second region A2 may not include at least one of the diaphragm 50 and the first electrode 60.

[0079] Here, the end face 150a of the insulating layer 150 in the second region A2, opposite to the pressure chamber substrate 10, is located closer to the pressure chamber substrate 10 than the end face 150b of the insulating layer 150 in the first region A1, which is opposite to the pressure chamber substrate 10. For example, by over-etching when patterning the common lead electrodes 91, the end face 150a of the insulating layer 150 is located closer to the pressure chamber substrate 10 than the end face 150b. As a result, the thickness of the insulating layer 150 in the second region A2 is thinner than the thickness of the insulating layer 150 in the first region A1. Of course, the position of the end face of the insulating layer 150 in each region is not particularly limited, and the end face of the insulating layer 150 may be planar throughout.

[0080] The third region A3 is adjacent to the second region A2, and is the region in which the diaphragm 50, the first electrode 60, the piezoelectric layer 70, the wiring layer 85, the insulating layer 150, and the individual lead electrodes 92 are stacked in this order from the pressure chamber substrate 10 side. In Figure 5, the third region A3 is the region adjacent to the second region A2 on the +X direction side. In other words, in the X-axis direction, the second region A2 is located between the first region A1 and the third region A3. The range of the first region A1 in the X-axis direction is not particularly limited, but it is preferable that it is wider than the range of the third region A3.

[0081] The fourth region A4 is adjacent to the first region A1, and is a region in which the diaphragm 50, the first electrode 60, the piezoelectric layer 70, the second electrode 80, and the second auxiliary wiring section 94(91) are stacked in this order from the pressure chamber substrate 10 side, and in which the insulating layer 150 is not stacked. In other words, in the fourth region A4, the second electrode 80 and the second auxiliary wiring section 94(91) are electrically connected.

[0082] In this embodiment, the region between the first region A1 and the active region A0 in the X-axis direction is the fourth region A4. That is, in the X-axis direction, the first region A1 is located between the fourth region A4 and the second region A2. The range of the fourth region A4 in the X-axis direction is not particularly limited, but it is preferably wider than the range of the first region A1.

[0083] Furthermore, the fifth region A5 is a region in which the diaphragm 50, the first electrode 60, and the individual lead electrodes 92 are stacked in this order from the pressure chamber substrate 10 side, and the piezoelectric layer 70, the wiring layer 85, and the insulating layer 150 are not stacked, and is located on the opposite side from the pressure chamber 12 from the third region A3.

[0084] Furthermore, as described above, the recording head 1 has a protective substrate 30 that demarcates the holding portion 31, which is the space in which the piezoelectric element 300 is housed, and is bonded to the pressure chamber substrate 10, etc., by adhesive. In this embodiment, as shown in Figure 6, the protective substrate 30 is bonded in the second region A2 via an insulating layer 150 and adhesive 160.

[0085] During bonding, the protective substrate 30 is pressed in the Z-axis direction. As a result, in the first region A1 and the third region A3, adhesive is squeezed out from between the protective substrate 30 and the common lead electrode 91 and the individual lead electrode 92, and in practice, the protective substrate 30 may be in substantial contact with the common lead electrode 91 and the individual lead electrode 92.

[0086] Furthermore, the protective substrate 30 is joined to the second auxiliary wiring section 94(91) in the first region A1 via adhesive 160. The second auxiliary wiring section 94(91) to which the protective substrate 30 is joined has steps 95 with different heights in the Z-axis direction from near the first region A1 to the fourth region A4. When joining the protective substrate 30, excess adhesive 160 is stored in these steps 95, suppressing the flow of adhesive 160 toward the active section 310.

[0087] As described above, the diaphragm 50, the first electrode 60, the piezoelectric layer 70, the second electrode 80, the second auxiliary wiring section 94 (91), the individual lead electrodes 92, and the insulating layer 150 are stacked in a predetermined order in each region, thereby suppressing damage to the piezoelectric layer 70 in the portion corresponding to the exposed section 71.

[0088] In more detail, in the first region A1, the exposed portion 71 of the piezoelectric layer 70 is covered by the insulating layer 150, thereby suppressing the intrusion of moisture into the piezoelectric layer 70. Furthermore, in the second region A2, the common lead electrode 91 is located on the insulating layer 150, and in the third region A3, the ends of the individual lead electrodes 92 are located on the insulating layer 150. This improves the insulation between the common lead electrode 91 and the individual lead electrodes 92, and also suppresses short circuits due to migration.

[0089] In particular, because the end face 150a of the insulating layer 150 in the second region A2 is located closer to the pressure chamber substrate 10 than the end face 150b of the first region A1, the migration path between the common lead electrode 91 and the individual lead electrode 92 is lengthened, making short circuits due to migration less likely. In addition, since residues of the common lead electrode 91 and individual lead electrode 92 can be reliably removed from the second region A2 during the manufacturing process, short circuits due to migration are less likely to occur.

[0090] Furthermore, by providing an insulating layer 150 on the exposed portion 71 corresponding to the boundary between the active portion 310 and the inactive portion 320 of the piezoelectric element 300, mechanical damage to the piezoelectric layer 70 at the boundary can be suppressed. As a result, the destruction of the piezoelectric layer 70 can be suppressed. In addition, since the insulating layer 150 is provided only partially and not covering the entire active portion 310 of the piezoelectric element 300, a decrease in the displacement of the piezoelectric element 300 is also suppressed.

[0091] As described above, the recording head 1 according to this embodiment includes a piezoelectric element 300 comprising a first electrode 60, a piezoelectric layer 70, and a second electrode 80; a common lead electrode 91 which is a first conductive layer electrically connected to the second electrode 80; an insulating layer 150 formed of an insulating material; a diaphragm 50 which vibrates when driven by the piezoelectric element 300; and a pressure chamber substrate 10 which partitions a pressure chamber 12 that applies pressure to a liquid by the vibration of the diaphragm 50.

[0092] In the active region A0 facing the pressure chamber 12, the diaphragm 50, the first electrode 60, the piezoelectric layer 70, and the second electrode 80 are stacked in this order from the pressure chamber substrate 10 side. The region outside the active region A0 in the X-axis direction, which is the longitudinal direction of the pressure chamber 12, includes a first region A1 in which the piezoelectric layer 70, the second electrode 80, the insulating layer 150, and the second auxiliary wiring section 94 (91), which is the first conductive layer, are stacked in this order from the pressure chamber substrate 10 side, and a second region A2 in which the piezoelectric layer 70 and the insulating layer 150 are stacked in this order from the pressure chamber substrate 10 side, but the second electrode 80 (including the wiring layer 85) and the second auxiliary wiring section 94 are not stacked.

[0093] By adopting this configuration, compared to the conventional configuration shown below, the adhesion of the insulating layer 150 to the portion corresponding to the exposed portion 71 can be improved, and the destruction of the piezoelectric layer 70 can be suppressed.

[0094] In conventional configurations, in an adjacent region adjacent to the second region A2 (corresponding to the first region A1 according to the present invention), the piezoelectric layer 70, the second electrode 80, the second auxiliary wiring section 94(91), and the insulating layer 150 are laminated in this order from the pressure chamber substrate 10 side. In other words, in conventional configurations, in the above adjacent region, the insulating layer 150 is laminated on the -Z side of the second auxiliary wiring section 94(91).

[0095] In this conventional configuration, the adhesion between the exposed portion 71 on the surface of the piezoelectric layer 70 and the insulating layer 150 may decrease. This problem occurs due to a step difference in the insulating layer 150 formed at the boundary between the second region A2, where the second auxiliary wiring portion 94(91) is not formed, and the adjacent region, where the second auxiliary wiring portion 94(91) is formed. In other words, this problem occurs because the height of the insulating layer 150 in the Z-axis direction differs significantly between the second region A2 and the adjacent region.

[0096] If the step difference of the insulating layer 150 at the boundary between the second region A2 and the adjacent region is large, then during the formation process of the insulating layer 150, for example, uneven application of spin coating or poor adhesion of the resist is likely to occur, and the formation of the insulating layer 150 may become unstable using general methods.

[0097] From the above viewpoint, by providing a configuration of the present invention that includes a first region A1 in which the piezoelectric layer 70, the second electrode 80, the insulating layer 150, and the second auxiliary wiring portion 94 (91), which is the first conductive layer, are laminated in this order from the pressure chamber substrate 10 side, and a second region A2 in which the piezoelectric layer 70 and the insulating layer 150 are laminated in this order from the pressure chamber substrate 10 side, and the second electrode 80 (including the wiring layer 85) and the second auxiliary wiring portion 94 are not laminated, the adhesion of the insulating layer 150 can be improved and the destruction of the piezoelectric layer 70 can be suppressed.

[0098] Here, the thickness of the second auxiliary wiring portion 94(91), which is the first conductive layer, is greater than the thickness of the second electrode 80. By making the first conductive layer thicker in this way, the electrical resistance is reduced, and the uneven distribution of charge at the second electrode 80 is suppressed, while the second electrode 80 can be made relatively thin, making the displacement of the flexible portion of the piezoelectric element 300 more efficient. Furthermore, according to the present invention, in the first region A1, the insulating layer 150 is laminated on the +Z side of the second auxiliary wiring portion 94(91), so even if the second auxiliary wiring portion 94(91) is formed to be relatively thick, the adhesion of the insulating layer 150 can be increased in the portion corresponding to the exposed portion 71, and the destruction of the piezoelectric layer 70 can be suppressed.

[0099] Furthermore, the end face 150a of the insulating layer 150 in the second region A2, opposite to the pressure chamber substrate 10, is located closer to the pressure chamber substrate 10 than the end face 150b of the insulating layer 150 in the first region A1, which is opposite to the pressure chamber substrate 10. As a result, compared to the case where, for example, the end face 150a of the insulating layer 150 in the second region A2, which is opposite to the pressure chamber substrate 10, and the end face 150b of the insulating layer 150 in the first region A1, which is opposite to the pressure chamber substrate 10, are located at the same position along the Z-axis, the migration path between the common lead electrode 91 formed on the insulating layer 150 and, for example, the individual lead electrode 92 becomes longer, making it less likely for a short circuit between the common lead electrode 91 and the individual lead electrode 92 due to migration to occur. In addition, since residues of the common lead electrode 91 and individual lead electrode 92 can be reliably removed from the second region A2 during the manufacturing process, short circuits due to migration are less likely to occur.

[0100] Furthermore, the thickness of the piezoelectric layer 70 is thinner in the second region A2 than in the first region A1. As a result, the difference between the end face 150a of the insulating layer 150 in the second region A2 and the end face 150b of the insulating layer 150 in the first region A1 becomes larger, making it even less likely for a short circuit to occur between the common lead electrode 91 and, for example, the individual lead electrode 92 due to migration. In addition, since the piezoelectric layer with low insulation that forms near the interface between the piezoelectric layer 70 and the second electrode 80 can be reliably removed during the manufacturing process, it becomes easier to prevent short circuits.

[0101] Furthermore, the region adjacent to the second region A2 includes a third region A3 in which an insulating layer 150 and individual lead electrodes 92, which are second conductive layers electrically connected to the first electrode 60, are laminated. In the longitudinal direction of the pressure chamber 12, the second region A2 is located between the first region A1 and the third region A3. In this configuration, short circuits between the common lead electrode 91 and the individual lead electrodes 92 due to migration become less likely.

[0102] Furthermore, the thickness of the individual lead electrodes 92, which are the second conductive layer, is greater than the thickness of the first electrode 60. According to the present invention, even when the individual lead electrodes 92 are formed to be relatively thick, the destruction of the piezoelectric layer 70 can be suppressed in the portion corresponding to the exposed portion 71.

[0103] Furthermore, the region adjacent to the first region A1 includes a fourth region A4 in which the piezoelectric layer 70, the second electrode 80, and the second auxiliary wiring section 94 are stacked in that order. In the X-axis direction, which is the longitudinal direction of the pressure chamber 12, the first region A1 is located between the fourth region A4 and the second region A2. Even with this configuration including the fourth region A4, the destruction of the piezoelectric layer 70 in the portion corresponding to the exposed portion 71 can be suppressed.

[0104] Furthermore, in the X-axis direction, which is the longitudinal direction of the pressure chamber 12, the first region A1 is wider than the third region A3. This improves reliability. The fourth region A4 and the first region A1 are active regions 310. The fourth region A4 is a region where the second auxiliary wiring section 94 is directly provided on the second electrode 80, and the potential difference between the second electrode 80 and the first electrode 60 is relatively large. In the first region A1, the second auxiliary wiring section 94 is not directly provided on the second electrode 80, and the potential difference between the second electrode 80 and the first electrode 60 is relatively small. On the other hand, the third region A3 is an inactive region 320.

[0105] In other words, in the configuration of this embodiment, a first region A1, which is an active region 310 with a relatively small potential difference between electrodes, exists between the fourth region A4, which is an active region 310 with a relatively large potential difference between electrodes, and the third region A3, which is an inactive region 320.

[0106] Therefore, the first region A1 functions as a buffer region between the fourth region A4 and the third region A3. By ensuring a relatively wide area for this buffer region A1, cracks in the piezoelectric layer 70 can be suppressed more reliably.

[0107] Furthermore, in the X-axis direction, which is the longitudinal direction of the pressure chamber 12, the fourth region A4 is wider than the first region A1. This makes it possible to reduce the resistance value of the second electrode 80 by the second auxiliary wiring section 94 while also miniaturizing the recording head 1.

[0108] Furthermore, it has a protective substrate 30 that partitions the space in which the piezoelectric element 300 is housed, and the protective substrate 30 is joined to the insulating layer 150 in the second region A2 via an adhesive 160. As a result, the adhesive 160 further enhances the insulation of the exposed portion 71 of the piezoelectric layer 70.

[0109] Furthermore, the region adjacent to the first region A1 includes a fourth region A4 in which a piezoelectric layer 70, a second electrode 80, and a second auxiliary wiring portion 94(91), which is the first conductive layer, are stacked in this order. In the X-axis direction, which is the longitudinal direction of the pressure chamber 12, the first region A1 is located between the fourth region A4 and the second region A2, and the second auxiliary wiring portion 94(91), which is the first conductive layer, has a step 95 from the first region A1 to the fourth region A4, and the protective substrate 30 is joined to the second auxiliary wiring portion 94(91), which is the first conductive layer, in the first region A1 via adhesive 160.

[0110] As a result, when the protective substrate 30 is joined, excess adhesive is stored in this step 95, and the flow of adhesive toward the active part 310 is suppressed. Therefore, for example, it is possible to suppress the adhesion of adhesive to the active part 310 and the resulting impact on the fluctuation characteristics of the diaphragm 50 and the jetting characteristics of the recording head 1.

[0111] (Embodiment 2) Figure 7 is an enlarged cross-sectional view showing the main part of the recording head according to Embodiment 2. This embodiment is a modified example of the laminated structure of the diaphragm 50, first electrode 60, piezoelectric layer 70, second electrode 80 (including wiring layer 85), second auxiliary wiring portion 94 of the common lead electrode 91 which is the first conductive layer, individual lead electrodes 92 which is the second conductive layer, and insulating layer 150 in the region outside the pressure chamber 12. The other configurations are the same as in Embodiment 1. The same reference numerals are used for the same components as in Embodiment 1, and redundant descriptions are omitted.

[0112] Specifically, as shown in Figure 7, the insulating layer 150 according to this embodiment is formed to cover a portion of the exposed portion 71 of the piezoelectric layer 70 in the X-axis direction. That is, the insulating layer 150 is continuously provided in the X-axis direction from above the second electrode 80 to partway up the exposed portion 71. In other words, the insulating layer 150 is provided to cover the end portion 80b of the second electrode 80 together with a portion of the exposed portion 71 of the piezoelectric layer 70. Note that the end portion 85a of the wiring layer 85 is not covered by the insulating layer 150.

[0113] Therefore, the region outside the active region A0 in the X-axis direction includes the first region A1, the second region A2, the fourth region A4, the fifth region A5, and the sixth region A6, but does not include the third region A3.

[0114] The sixth region A6 is the region adjacent to the first region A1 on the opposite side of the second region A2, in which the diaphragm 50, the first electrode 60, and the piezoelectric layer 70 are stacked in this order from the pressure chamber substrate 10 side, and the second electrode 80, the insulating layer 150, and the wiring layer 85 are not stacked in this region.

[0115] In this embodiment as well, similar to the embodiment described above, the destruction of the piezoelectric layer 70 in the portion corresponding to the exposed portion 71 can be suppressed. Furthermore, the absence of the third region A3 allows for a more compact recording head 1.

[0116] (Embodiment 3) Figure 8 is an enlarged cross-sectional view showing the main part of the recording head according to Embodiment 3. This embodiment is an example in which the position where the protective substrate 30 is joined by the adhesive layer is changed, and the other configurations are the same as in Embodiment 1. The same reference numerals are used for the same components as in Embodiment 1, and redundant descriptions are omitted.

[0117] As shown in Figure 8, the protective substrate 30 according to this embodiment is bonded in the fifth region A5 to a laminate containing a piezoelectric element 300, a diaphragm 50, and a pressure chamber substrate 10 via adhesive 160. That is, in Figure 8, the protective substrate 30 is bonded in the fifth region A5 to the individual lead electrodes 92 via adhesive 160.

[0118] As described above, the recording head 1 according to this embodiment has a protective substrate 30 that demarcates the holding portion 31, which is the space in which the piezoelectric element 300 is housed. The protective substrate 30 is bonded to a laminate including the piezoelectric element 300, the diaphragm 50, and the pressure chamber substrate 10 via an adhesive 160 in the fifth region A5, which is the region opposite to the pressure chamber 12 in the second region A2 in the X-axis direction. During bonding, the protective substrate 30 is pressed in the Z-axis direction. As a result, in the fifth region A5, the adhesive is squeezed out from between the protective substrate 30 and the individual lead electrodes 92, and in practice, the protective substrate 30 may be in substantial contact with the individual lead electrodes 92.

[0119] Furthermore, in the recording head 1 of this embodiment, as in the embodiment described above, the destruction of the piezoelectric layer 70 can be suppressed in the portion corresponding to the exposed portion 71.

[0120] Furthermore, in the configuration of this embodiment, the insulating layer 150 is not sandwiched between the pressure chamber substrate 10 and the protective substrate 30. Therefore, when the protective substrate 30 is joined, the insulating layer 150 is not pressed, and no residual stress remains between it and the protective substrate 30, thus suppressing peeling of the insulating layer 150. In addition, when the protective substrate 30 is joined, excess adhesive 160 is stored in the gap between the second auxiliary wiring section 94 (91) and the individual lead electrodes 92, that is, in the portion corresponding to the exposed section 71, and the flow of adhesive 160 toward the active section 310 is suppressed.

[0121] Therefore, for example, it is possible to suppress the adhesion of adhesive 160 to the active part 310, which would affect the fluctuation characteristics of the diaphragm 50 and the jetting characteristics of the recording head 1. In addition, the adhesive 160 stored in the gap between the second auxiliary wiring part 94 (91) and the individual lead electrodes 92 covers the exposed part 71 of the piezoelectric layer 70, which has the effect of improving insulation.

[0122] (Other embodiments) Although various embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above.

[0123] For example, in the above embodiment, a configuration in which the first region A1 and the second region A2 are adjacent is illustrated, but these first region A1 and second region A2 do not necessarily have to be adjacent. For example, as shown in Figure 9, a seventh region A7 may be provided between the first region A1 and the second region A2. The seventh region A7 is a region in which the diaphragm 50, the first electrode 60, the piezoelectric layer 70, the second electrode 80, and the insulating layer 150 are stacked in this order from the pressure chamber substrate 10 side, and the second auxiliary wiring section 94(91) is not stacked.

[0124] For example, as shown in Figure 10, an eighth region A8 may be provided between the first region A1 and the second region A2. The eighth region A8 is a region in which the diaphragm 50, the first electrode 60, the piezoelectric layer 70, the insulating layer 150, and the common lead electrode 91 are stacked in this order from the pressure chamber substrate 10 side, and the second electrode 80 is not stacked.

[0125] In configurations having these seventh region A7 and eighth region A8, similar to the embodiments described above, the destruction of the piezoelectric layer 70 can be suppressed in the portion corresponding to the exposed portion 71.

[0126] Furthermore, the recording head 1 of each of these embodiments is mounted on an inkjet recording device, which is an example of a liquid jetting device. Figure 11 is a schematic diagram showing an example of an inkjet recording device, which is an example of a liquid jetting device according to one embodiment.

[0127] In the inkjet recording device I shown in Figure 11, the recording head 1 is mounted on a carriage 3 and is equipped with a detachable cartridge 2 that constitutes the ink supply means. The carriage 3 on which the recording head 1 is mounted is movably mounted in the axial direction of the carriage shaft 5 attached to the main body of the device 4.

[0128] The driving force of the drive motor 6 is transmitted to the carriage 3 via multiple gears (not shown) and a timing belt 7, causing the carriage 3, on which the recording head 1 is mounted, to move along the carriage axis 5. Meanwhile, the main body of the device 4 is provided with transport rollers 8 as a transport means, and the recording sheet S, which is a recording medium such as paper, is transported by the transport rollers 8. Note that the transport means for transporting the recording sheet S is not limited to transport rollers, but may also be a belt or a drum.

[0129] In this type of inkjet recording device I, the recording sheet S is transported in the +X direction relative to the recording head 1, and the carriage 3 is moved back and forth in the Y direction relative to the recording sheet S, while ink droplets are ejected from the recording head 1, causing ink droplets to land on almost the entire surface of the recording sheet S, thus performing printing.

[0130] Furthermore, while the inkjet recording device I described above exemplified a device in which the recording head 1 is mounted on a carriage 3 and moves back and forth in the Y direction, which is the main scanning direction, the present invention is not limited to this. For example, the present invention can also be applied to so-called line-type recording devices in which the recording head 1 is fixed and printing is performed simply by moving a recording sheet S such as paper in the X direction, which is the sub-scanning direction.

[0131] In the embodiments described above, an inkjet recording head was given as an example of a liquid ejection head, and an inkjet recording device was given as an example of a liquid ejection device to explain the present invention. However, the present invention broadly applies to liquid ejection heads and liquid ejection devices in general. The present invention can also be applied to liquid ejection heads and liquid ejection devices that eject liquids other than ink. Examples of other liquid ejection heads include various recording heads used in image recording devices such as printers, colorant ejection heads used in the manufacture of color filters for liquid crystal displays, electrode material ejection heads used in electrode formation for organic EL displays and FEDs (field emission displays), and bio-organic material ejection heads used in biochip manufacturing. The present invention can also be applied to liquid ejection devices equipped with such liquid ejection heads.

[0132] Furthermore, the present invention is not limited to liquid ejection heads, such as those found in inkjet recording heads, but can also be applied to piezoelectric devices such as ultrasonic devices, motors, pressure sensors, pyroelectric elements, and ferroelectric elements. The present invention can also be applied to complete systems utilizing these piezoelectric devices, such as liquid ejection devices using the above-mentioned liquid ejection heads, ultrasonic sensors using the above-mentioned ultrasonic devices, robots using the above-mentioned motors as a driving source, IR sensors using the above-mentioned pyroelectric elements, and ferroelectric memories using ferroelectric elements. [Explanation of Symbols]

[0133] 1... Inkjet recording head (recording head), 2... Cartridge, 3... Carriage, 4... Device body, 5... Carriage shaft, 6... Drive motor, 7... Timing belt, 8... Conveyor roller, 10... Pressure chamber substrate (substrate), 12... Pressure chamber (recess), 15... Communication plate, 16... Nozzle communication passage, 17... First manifold section, 18... Second manifold section, 19... Supply communication passage, 20... Nozzle plate, 21... Nozzle, 30... Protective substrate, 31... Holding section, 32... Through hole, 40... Case member, 41... Housing section, 42... Third manifold section, 43... Connection port, 44... Inlet, 45... Compliance substrate, 46... Sealing film, 47... Fixing substrate, 48... Opening, 49... Compliant Part A0: Diaphragm, 51: Elastic film, 52: Insulator film, 60: First electrode, 70: Piezoelectric layer, 71: Exposed part, 72: Recess, 80: Second electrode, 85: Wiring layer, 91: Common lead electrode, 92: Individual lead electrode, 93: First auxiliary wiring part, 94: Second auxiliary wiring part, 95: Step, 100: Manifold, 120: Wiring board, 121: Drive circuit, 150: Insulating layer, 160: Adhesive, 300: Piezoelectric element, 310: Active part, 320: Inactive part, I: Inkjet recording device (recording device), S: Recording sheet, A0: Active area, A1: First area, A2: Second area, A3: Third area, A4: Fourth area, A5: Fifth area, A6: Sixth area, A7: Seventh area, A8: Eighth area

Claims

1. A piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode, A first conductive layer electrically connected to the second electrode, An insulating layer formed of insulating material, A diaphragm that vibrates by driving the piezoelectric element, A pressure chamber substrate that partitions a pressure chamber in which pressure is applied to a liquid by the vibration of the aforementioned diaphragm, It has, In the active region facing the pressure chamber, the diaphragm, the first electrode, the piezoelectric layer, and the second electrode are stacked in this order from the pressure chamber substrate side. The region outside the active region in the longitudinal direction of the pressure chamber is, The piezoelectric layer, the second electrode, the insulating layer, and the first conductive layer are stacked in this order from the pressure chamber substrate side to form a first region. The piezoelectric layer and the insulating layer are laminated in this order from the pressure chamber substrate side, and the second region includes a region where the second electrode and the first conductive layer are not laminated. The thickness of the piezoelectric layer is thinner in the second region than in the first region. A liquid spray head characterized by the following features.

2. The thickness of the first conductive layer is greater than the thickness of the second electrode. The liquid spray head according to feature 1.

3. The end face of the insulating layer in the second region that is opposite to the pressure chamber substrate is located closer to the pressure chamber substrate than the end face of the insulating layer in the first region that is opposite to the pressure chamber substrate. The liquid spray head according to feature 2.

4. The region adjacent to the aforementioned second region is, The third region includes the insulating layer and a second conductive layer electrically connected to the first electrode, In the longitudinal direction of the pressure chamber, the second region is located between the first region and the third region. A liquid spray head according to any one of claims 1 to 3.

5. The thickness of the second conductive layer is greater than the thickness of the first electrode. The liquid spray head according to feature 4.

6. The region adjacent to the first region is, The piezoelectric layer, the second electrode, and the first conductive layer are stacked in this order, including a fourth region. In the longitudinal direction of the pressure chamber, the first region is located between the fourth region and the second region. The liquid spray head according to feature 4.

7. A piezoelectric element comprising a first electrode, a piezoelectric layer, and a second electrode, A first conductive layer electrically connected to the second electrode, An insulating layer formed of insulating material, A diaphragm that vibrates by driving the piezoelectric element, A pressure chamber substrate that partitions a pressure chamber in which pressure is applied to a liquid by the vibration of the aforementioned diaphragm, It has, In the active region facing the pressure chamber, the diaphragm, the first electrode, the piezoelectric layer, and the second electrode are stacked in this order from the pressure chamber substrate side. The region outside the active region in the longitudinal direction of the pressure chamber is, The piezoelectric layer, the second electrode, the insulating layer, and the first conductive layer are stacked in this order from the pressure chamber substrate side to form a first region. The piezoelectric layer and the insulating layer are laminated in this order from the pressure chamber substrate side, and the second region includes a region where the second electrode and the first conductive layer are not laminated. The region adjacent to the second region includes a third region in which the insulating layer and a second conductive layer electrically connected to the first electrode are laminated. In the longitudinal direction of the pressure chamber, the second region is located between the first region and the third region. In the longitudinal direction of the pressure chamber, the first region is wider than the third region. A liquid spray head characterized by the following features.

8. A piezoelectric element comprising a first electrode, a piezoelectric layer, and a second electrode, A first conductive layer electrically connected to the second electrode, An insulating layer formed of insulating material, A diaphragm that vibrates by driving the piezoelectric element, A pressure chamber substrate that partitions a pressure chamber in which pressure is applied to a liquid by the vibration of the aforementioned diaphragm, It has, In the active region facing the pressure chamber, the diaphragm, the first electrode, the piezoelectric layer, and the second electrode are stacked in this order from the pressure chamber substrate side. The region outside the active region in the longitudinal direction of the pressure chamber is, The piezoelectric layer, the second electrode, the insulating layer, and the first conductive layer are stacked in this order from the pressure chamber substrate side to form a first region. The piezoelectric layer and the insulating layer are laminated in this order from the pressure chamber substrate side, and the second region includes a region where the second electrode and the first conductive layer are not laminated. The region adjacent to the first region includes a fourth region in which the piezoelectric layer, the second electrode, and the first conductive layer are stacked in this order. In the longitudinal direction of the pressure chamber, the first region is located between the fourth region and the second region. In the longitudinal direction of the pressure chamber, the fourth region is wider than the first region. A liquid spray head characterized by the following features.

9. The facility has a protective substrate that partitions the space in which the piezoelectric element is housed, The protective substrate is bonded to the insulating layer in the second region via an adhesive. A liquid spray head according to any one of claims 1 to 3, 7, and 8.

10. A piezoelectric element comprising a first electrode, a piezoelectric layer, and a second electrode, A first conductive layer electrically connected to the second electrode, An insulating layer formed of insulating material, A diaphragm that vibrates by driving the piezoelectric element, A pressure chamber substrate that partitions a pressure chamber in which pressure is applied to a liquid by the vibration of the aforementioned diaphragm, It has, In the active region facing the pressure chamber, the diaphragm, the first electrode, the piezoelectric layer, and the second electrode are stacked in this order from the pressure chamber substrate side. The region outside the active region in the longitudinal direction of the pressure chamber is, The piezoelectric layer, the second electrode, the insulating layer, and the first conductive layer are stacked in this order from the pressure chamber substrate side to form a first region. The piezoelectric layer and the insulating layer are laminated in this order from the pressure chamber substrate side, and the second region includes a region where the second electrode and the first conductive layer are not laminated. The facility has a protective substrate that partitions the space in which the piezoelectric element is housed, The protective substrate is bonded to the insulating layer in the second region via an adhesive. The region adjacent to the first region is, The piezoelectric layer, the second electrode, and the first conductive layer are stacked in this order, including a fourth region. In the longitudinal direction of the pressure chamber, the first region is located between the fourth region and the second region. The first conductive layer has a step from the first region to the fourth region, The protective substrate is bonded to the first conductive layer in the first region via an adhesive. A liquid spray head characterized by the following features.

11. The facility has a protective substrate that partitions the space in which the piezoelectric element is housed, The protective substrate is bonded via an adhesive to a laminate including the piezoelectric element, the diaphragm, and the pressure chamber substrate in the region of the second region opposite to the pressure chamber. A liquid spray head according to any one of claims 1 to 3, 7, and 8.

12. A liquid spray head as described in any one of claims 1 to 3, 7, and 8. A liquid injection device characterized by the following features.

13. A substrate having a recess, A diaphragm provided on one side of the aforementioned substrate, A piezoelectric element including a first electrode, a piezoelectric layer, and a second electrode, A first conductive layer electrically connected to the second electrode, It has an insulating layer formed of an insulating material, In the active region facing the recess, the diaphragm, the first electrode, the piezoelectric layer, and the second electrode are stacked in this order from the substrate side. The region of the recess in the longitudinal direction that is outside the active region is, A first region is formed in which the piezoelectric layer, the second electrode, the insulating layer, and the first conductive layer are stacked in this order from the substrate side. The piezoelectric layer and the insulating layer are laminated in this order from the substrate side, and the second region includes a region where the second electrode and the first conductive layer are not laminated. The thickness of the piezoelectric layer is thinner in the second region than in the first region. A piezoelectric device characterized by the following features.

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