Liquid ejection head

Abstract

To improve performance of a piezoelectric element.SOLUTION: A liquid ejection head includes a piezoelectric element and a vibration plate. A first electrode, a piezoelectric layer, and a second electrode of the piezoelectric element are laminated in a lamination direction which is a direction from the vibration plate to the piezoelectric element in a written order. When a region where the first electrode, the piezoelectric layer, and the second electrode overlap when viewed in the lamination direction is referred to as a first region and a region where the first electrode does not overlap the piezoelectric layer and the second electrode and overlaps the vibration plate is referred to as a second region, the first electrode is disposed spanning the first region and the second region. A first mixed layer formed of a mixed material, containing lead and a material forming the first electrode, is provided at the second region on the first electrode.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Liquid ejection devices, such as piezoelectric inkjet printers, use liquid ejection heads that eject liquids such as ink. For example, the head described in Patent Document 1 includes a diaphragm and a piezoelectric element. The piezoelectric element is configured by sequentially laminating a lower electrode, a piezoelectric film, and an upper electrode on a diaphragm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-319714 Summary of the Invention [Problem to be solved by the invention]

[0004] In the head described in Patent Document 1, the diffusion of lead from the piezoelectric film to the lower electrode increases the electrical resistance of the lower electrode, which may result in a decrease in the performance of the piezoelectric element. [Means for solving the problem]

[0005] In order to solve the above problems, one embodiment of a liquid ejection head disclosed herein comprises a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode, and a vibration plate connected to the piezoelectric element, wherein the first electrode, the piezoelectric layer, and the second electrode are stacked in this order in a stacking direction that is a direction from the vibration plate toward the piezoelectric element, and when, in the stacking direction, a region where the first electrode, the piezoelectric layer, and the second electrode overlap is defined as a first region, and a region where the first electrode overlaps the vibration plate without overlapping the piezoelectric layer and the second electrode is defined as a second region, the first electrode is arranged across the first region and the second region, and a first mixed layer composed of a mixed material containing lead and the material that constitutes the first electrode is provided on the first electrode in the second region. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a configuration diagram that schematically illustrates a liquid ejection apparatus that includes a liquid ejection head according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the liquid ejection head according to the embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is a plan view showing a part of the liquid ejection head according to the embodiment. [Figure 5] FIG. 5 is a cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 6 is an enlarged view of a portion Q in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual dimensions and are shown schematically to facilitate understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0008] In the following description, the mutually intersecting X-axis, Y-axis, and Z-axis are used as appropriate. In the following description, one direction along the X-axis is the X1 direction, and the direction opposite the X1 direction is the X2 direction. Similarly, the opposite directions along the Y-axis are the Y1 direction and the Y2 direction. Furthermore, the opposite directions along the Z-axis are the Z1 direction and the Z2 direction. The Z1 direction is an example of a "stacking direction." Furthermore, viewing in the direction along the Z-axis is sometimes referred to as a "planar view."

[0009] Here, the Z axis is typically the vertical axis, and the Z2 direction corresponds to the downward vertical direction. However, the Z axis does not have to be the vertical axis. Furthermore, the X axis, Y axis, and Z axis are typically perpendicular to each other, but are not limited to this. For example, they may intersect at an angle between 80° and 100°.

[0010] 1. Embodiment 1-1. Overall configuration of the liquid ejection device FIG. 1 is a schematic diagram illustrating a liquid ejection device 100 equipped with a liquid ejection head 50 according to an embodiment. The liquid ejection device 100 is an inkjet printing device that ejects ink, an example of a liquid, as droplets onto a medium M. The medium M is typically printing paper. However, the medium M is not limited to printing paper, and may be a printing target made of any material, such as a resin film or fabric.

[0011] As shown in FIG. 1, the liquid ejection device 100 includes a liquid container 10, a control unit 20, a transport mechanism 30, a moving mechanism 40, and a liquid ejection head 50.

[0012] The liquid container 10 is a container that stores ink. Specific examples of the liquid container 10 include a cartridge that is detachable from the liquid ejection device 100, a bag-shaped ink pack made of flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 10 is not particularly limited and can be any type.

[0013] The control unit 20 includes a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls the operation of each element of the liquid ejection device 100.

[0014] The transport mechanism 30 transports the medium M in the Y2 direction under the control of the control unit 20. The movement mechanism 40 reciprocates the liquid ejection head 50 in the X1 direction and the X2 direction under the control of the control unit 20. In the example shown in FIG. 1, the movement mechanism 40 has a substantially box-shaped carriage 41 that houses the liquid ejection head 50, and a transport belt 42 to which the carriage 41 is fixed. Note that the number of liquid ejection heads 50 mounted on the carriage 41 is not limited to one, and may be multiple. In addition to the liquid ejection head 50, the carriage 41 may also be equipped with the aforementioned liquid container 10.

[0015] The liquid ejection head 50 ejects ink supplied from the liquid container 10 from each of a plurality of nozzles onto the medium M in the Z2 direction under the control of the control unit 20. This ejection is performed in parallel with the transport of the medium M by the transport mechanism 30 and the reciprocating movement of the liquid ejection head 50 by the movement mechanism 40, thereby forming an ink image on the surface of the medium M.

[0016] 1-2. Overall configuration of liquid ejection head Fig. 2 is an exploded perspective view of a liquid ejection head 50 according to an embodiment. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. As shown in Figs. 2 and 3, the liquid ejection head 50 has a flow path substrate 51, a pressure chamber substrate 52, a nozzle plate 53, a vibration absorber 54, a diaphragm 55, a plurality of piezoelectric elements 56, a sealing plate 57, a case 58, and a wiring substrate 59. The diaphragm 55 and the piezoelectric elements 56 constitute an actuator 1. In this way, the liquid ejection head 50 has the actuator 1 that includes the piezoelectric elements 56 and the diaphragm 55.

[0017] Here, a pressure chamber substrate 52, a vibration plate 55, a plurality of piezoelectric elements 56, a case 58, and a sealing plate 57 are disposed in an area positioned further in the Z1 direction than the flow path substrate 51. On the other hand, a nozzle plate 53 and a vibration absorber 54 are disposed in an area positioned further in the Z2 direction than the flow path substrate 51. Each element of the liquid ejection head 50 is roughly a plate-like member that is elongated in the direction along the Y axis, and is joined to one another by, for example, an adhesive.

[0018] As shown in FIG. 2, the nozzle plate 53 is a plate-like member provided with a plurality of nozzles N arranged in a direction along the Y-axis. Each nozzle N is a through-hole that allows ink to pass through. In this manner, the nozzle plate 53 has a plurality of nozzles N that eject ink. The nozzle plate 53 is manufactured by processing a silicon single crystal substrate using a semiconductor manufacturing technique that uses processing techniques such as dry etching or wet etching. However, other known methods and materials may also be used as appropriate to manufacture the nozzle plate 53.

[0019] The flow path substrate 51 is a plate-like member for forming ink flow paths. As shown in FIGS. 2 and 3 , the flow path substrate 51 is provided with an opening R1, multiple supply flow paths Ra, and multiple communication flow paths Na. The opening R1 is an elongated through-hole that extends in the direction along the Y-axis in a plan view viewed along the Z-axis so as to be continuous across the multiple nozzles N. On the other hand, the supply flow paths Ra and the communication flow paths Na are through-holes individually provided for each nozzle N. Each of the multiple supply flow paths Ra communicates with the opening R1. Like the nozzle plate 53 described above, the flow path substrate 51 is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, for example. However, other known methods and materials may also be used as appropriate for manufacturing the flow path substrate 51.

[0020] The pressure chamber substrate 52 is a plate-like member in which multiple pressure chambers C corresponding to the multiple nozzles N are formed. The pressure chambers C are located between the flow path substrate 51 and the vibration plate 55 and are spaces known as cavities for applying pressure to the ink filled in the pressure chambers C. The multiple pressure chambers C are arranged in a direction along the Y axis. Each pressure chamber C is formed by a hole 52a that opens on both sides of the pressure chamber substrate 52 and has an elongated shape extending in a direction along the X axis. Thus, the pressure chamber substrate 52 has multiple pressure chambers C that communicate with the nozzles N. The X2-direction end of each pressure chamber C communicates with the corresponding supply flow path Ra. Meanwhile, the X1-direction end of each pressure chamber C communicates with the corresponding communication flow path Na. The pressure chamber substrate 52, like the nozzle plate 53 described above, is manufactured by processing a silicon single crystal substrate using, for example, semiconductor manufacturing technology. However, other known methods and materials may be used as appropriate to manufacture each of the pressure chamber substrates 52.

[0021] A diaphragm 55 is disposed on the surface of the pressure chamber substrate 52 facing the Z1 direction. The diaphragm 55 is an elastically deformable plate-like member, and is connected to a piezoelectric element 56. Details of the diaphragm 55 will be described later with reference to FIG.

[0022] Piezoelectric elements 56 are arranged on the surface of the vibration plate 55 facing the Z1 direction. The piezoelectric elements 56 are passive elements that deform when supplied with a drive signal, and have an elongated shape extending in the direction along the X axis. One piezoelectric element 56 is provided for each pressure chamber, and multiple piezoelectric elements 56 are arranged in the direction along the Y axis so as to correspond to multiple pressure chambers C. When the vibration plate 55 vibrates in conjunction with the deformation of the piezoelectric elements 56, the pressure in the pressure chambers C fluctuates, causing ink to be ejected from the nozzles N. Details of the piezoelectric elements 56 will be described later with reference to Figures 4 to 6.

[0023] The case 58 is a case for storing ink to be supplied to the multiple pressure chambers C, and is bonded to the surface of the flow path substrate 51 facing the Z1 direction with an adhesive or the like. The case 58 is made of, for example, a resin material and manufactured by injection molding. The case 58 is provided with a storage section R2 and an inlet IH. The storage section R2 is a recessed portion whose outer shape corresponds to the opening R1 of the flow path substrate 51. The inlet IH is a through hole that communicates with the storage section R2. The space formed by the opening R1 and the storage section R2 functions as a liquid storage chamber R, which is a reservoir that stores ink. Ink is supplied to the liquid storage chamber R from the liquid container 10 via the inlet IH.

[0024] The vibration absorber 54 is an element for absorbing pressure fluctuations within the liquid storage chamber R. The vibration absorber 54 is, for example, a compliance substrate, which is a flexible sheet member that is elastically deformable. Here, the vibration absorber 54 is disposed on the surface of the flow path substrate 51 facing the Z2 direction so as to close the opening R1 and the multiple supply flow paths Ra of the flow path substrate 51 and form the bottom surface of the liquid storage chamber R.

[0025] The sealing plate 57 is a structure that protects the multiple piezoelectric elements 56 and reinforces the mechanical strength of the pressure chamber substrate 52 and the vibration plate 55. The sealing plate 57 is bonded to the surface of the vibration plate 55 with, for example, an adhesive. The sealing plate 57 has recesses that accommodate the multiple piezoelectric elements 56.

[0026] A wiring board 59 is bonded to the surface of the pressure chamber substrate 52 or the vibration plate 55 facing the Z1 direction. The wiring board 59 is a mounting component on which a plurality of wires are formed for electrically connecting the control unit 20 and the liquid ejection head 50. The wiring board 59 is a flexible wiring board such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable). A drive circuit 60 for driving the piezoelectric elements 56 is mounted on the wiring board 59. The drive circuit 60 selectively supplies drive signals for driving each piezoelectric element 56 to each piezoelectric element 56 via the wiring board 59.

[0027] 1-3. Details of the diaphragm and piezoelectric element Fig. 4 is a plan view showing a part of the liquid ejection head 50 according to the embodiment. Fig. 5 is a cross-sectional view taken along line BB in Fig. 4. The pressure chamber substrate 52, the piezoelectric element 56, and the vibration plate 55 will be described below in this order with reference to Figs. 4 and 5.

[0028] As shown in Figures 4 and 5, holes 52a that form pressure chambers C are provided in the pressure chamber substrate 52. Accordingly, wall-like partitions 52b extending in the direction along the X-axis are provided between two adjacent holes 52a in the pressure chamber substrate 52. The pressure chamber substrate 52 is manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. In Figure 4, the dashed line shows the planar shape of the holes 52a when formed by anisotropic etching on a silicon single crystal substrate with a (110) plane orientation. Note that the planar shape of the holes 52a is not limited to the example shown in Figure 4 and may be any shape.

[0029] Here, the pressure chambers C are formed after the piezoelectric elements 56 are formed. The pressure chambers C are formed, for example, by anisotropically etching one of the two surfaces of the silicon single crystal substrate after the piezoelectric elements 56 are formed, opposite the surface on which the piezoelectric elements 56 are formed. At this time, an etchant for the anisotropic etching is, for example, an aqueous potassium hydroxide (KOH) solution. At this time, if the elastic layer 55a is made of silicon oxide, the elastic layer 55a functions as a stopping layer that stops the anisotropic etching. After the pressure chambers C are formed as described above, the flow path substrate 51 and the like are bonded to the pressure chamber substrate 52 with an adhesive. Note that after the piezoelectric elements 56 are formed, the surface of the silicon single crystal substrate opposite the surface on which the piezoelectric elements 56 are formed is ground, as necessary, by CMP (chemical mechanical polishing) or the like to flatten that surface or adjust the thickness of the substrate.

[0030] As shown in Fig. 4, the piezoelectric element 56 overlaps the pressure chamber C in a plan view. As shown in Fig. 5, the piezoelectric element 56 has a first electrode 56a, a piezoelectric layer 56b, and a second electrode 56c, which are stacked in this order in the Z1 direction. That is, the first electrode 56a, the piezoelectric layer 56b, and the second electrode 56c are stacked in this order in a stacking direction DL, which is the direction from the vibration plate 55 toward the piezoelectric element 56. In addition to the first electrode 56a, the piezoelectric layer 56b, and the second electrode 56c, the piezoelectric element 56 also has a first mixed layer 56d, a second mixed layer 56e, a third mixed layer 56f, and a protective layer 56g.

[0031] The first electrode 56a, the piezoelectric layer 56b, and the second electrode 56c will be described below in order with reference to Figures 4 and 5. The first mixed layer 56d, the second mixed layer 56e, the third mixed layer 56f, and the protective layer 56g will be described later with reference to Figure 6.

[0032] The first electrode 56a is a strip-shaped common electrode that extends in the direction along the Y-axis so as to be continuous across the plurality of piezoelectric elements 56. A predetermined constant potential is supplied to the first electrode 56a.

[0033] The first electrode 56a includes, for example, a layer made of platinum (Pt), a layer made of iridium (Ir), and a layer made of titanium (Ti). That is, the electrode layer 56a1 includes platinum, iridium, and titanium. Platinum is an electrode material with excellent conductivity. Therefore, using platinum as a constituent material of the first electrode 56a can reduce the resistance of the first electrode 56a. Furthermore, when forming the piezoelectric layer 56b, the titanium island-shaped layer serves as a crystal nucleus, controlling the orientation of the piezoelectric layer 56b and improving the crystallinity or orientation of the piezoelectric layer 56b. Note that, instead of or in addition to these layers, layers made of other metal materials or conductive oxides may be provided. Furthermore, the layer may include a layer of a mixture or alloy of multiple metal materials.

[0034] The first electrode 56a is formed, for example, by a known film formation technique such as sputtering, and a known processing technique using photolithography, etching, etc., after the formation of the diaphragm 55. The thickness of the first electrode 56a is, for example, about 100 nm.

[0035] 4 and 5, the piezoelectric layer 56b has a strip shape extending in the direction along the Y-axis so as to be continuous across the plurality of piezoelectric elements 56. In the example shown in FIG. 4, the piezoelectric layer 56b has through-holes 56b1 extending in the direction along the X-axis, penetrating the piezoelectric layer 56b, in regions corresponding in plan view to the gaps between adjacent pressure chambers C. As a result, when viewed in the cross section shown in FIG. 5, the piezoelectric layer 56b is provided individually for each of the piezoelectric elements 56. Note that the piezoelectric layer 56b may be provided individually for each of the plurality of piezoelectric elements 56.

[0036] The piezoelectric layer 56b is made of a piezoelectric material containing lead as a constituent element. The piezoelectric material has a perovskite crystal structure represented by the general composition formula ABO3, such as lead zirconate titanate (Pb(Zr,Ti)O3). In addition to lead (Pb), the piezoelectric layer 56b may contain at least one element selected from the group consisting of vanadium (V), niobium (Nb), tantalum (Ta), nickel (Ni), phosphorus (P), arsenic (As), antimony (Sb), and bismuth (Bi). The lead contained in the piezoelectric material constituting the piezoelectric layer 56b may be an element that does not constitute part of the perovskite crystal structure.

[0037] Such a piezoelectric layer 56b is formed, for example, by forming a piezoelectric precursor layer uniformly by a sol-gel method after the first electrode 56a is formed, baking the precursor layer to crystallize it, and then patterning it by etching such as reactive ion etching (RIE) or ion milling.

[0038] The second electrodes 56c are individual electrodes spaced apart from one another and arranged for each piezoelectric element 56. Specifically, a plurality of second electrodes 56c extending in the direction along the X-axis are arranged in the direction along the Y-axis at intervals from one another. A drive signal including a predetermined voltage pulse is supplied from the control unit 20 to the second electrode 56c of each piezoelectric element 56.

[0039] The second electrode 56c is made of, for example, platinum (Pt). The material of the second electrode 56c is not limited to iridium, and may be, for example, a metal material such as titanium (Ti), iridium (Ir), aluminum (Al), nickel (Ni), gold (Au), or copper (Cu), or a conductive oxide such as lanthanum nickel oxide (LaNiO3:LNO) or strontium ruthenium oxide (SrRuO3:SRO). The second electrode 56c may be made of one of these metal materials alone, or two or more of them may be combined in a laminated form, for example.

[0040] The second electrode 56c is formed, for example, after the piezoelectric layer 56B is formed, by a known film formation technique such as sputtering, and a known processing technique using photolithography, etching, etc. The thickness of the second electrode 56c is, for example, about 150 nm.

[0041] In the piezoelectric element 56, when a voltage is applied between the first electrode 56a and the second electrode 56c, the piezoelectric layer 56b is deformed due to the inverse piezoelectric effect. A diaphragm 55 is connected to the piezoelectric element 56, and the diaphragm 55 vibrates in response to the deformation of the piezoelectric layer 56b.

[0042] 5, the diaphragm 55 has an elastic layer 55a and an insulating layer 55b, which are laminated in this order in the Z1 direction. Here, the insulating layer 55b is biased toward a position closer to the first electrode 56a in the thickness direction of the diaphragm 55.

[0043] The elastic layer 55a is a film made of, for example, silicon oxide (SiO2). The material making up the elastic layer 55a is not limited to SiO2, and may be a material containing one or more elements selected from titanium (Ti), silicon (Si), aluminum (Al), tantalum (Ta), chromium (Cr), iridium (Ir), hafnium (Hf), zirconium (Zr), and carbon (C) in the form of a simple substance, oxide, or nitride.

[0044] The thickness of the elastic layer 55a is determined depending on the thickness and width of the diaphragm 55 and is not particularly limited, but is, for example, within the range of 100 nm to 3000 nm.

[0045] Insulating layer 55b is, for example, a film made of zirconium oxide (ZrO2) and contains zirconium (Zr). By disposing insulating layer 55b containing zirconium in a position closer to first electrode 56a in the thickness direction of diaphragm 55, insulating layer 55b can suppress the diffusion of lead from first electrode 56a to elastic layer 55a. Note that the material constituting insulating layer 55b is not limited to ZrO2 and may be a material containing one or more elements selected from titanium (Ti), aluminum (Al), tantalum (Ta), chromium (Cr), hafnium (Hf), zirconium (Zr), and silicon (Si) in the form of an oxide or nitride.

[0046] The thickness of the insulating layer 55b is determined depending on the thickness and width of the diaphragm 55 and is not particularly limited, but is, for example, within the range of 100 nm to 2000 nm.

[0047] 5, the elastic layer 55a and the insulating layer 55b are in contact with each other. Note that another layer, such as an adhesive layer, may be interposed between the elastic layer 55a and the insulating layer 55b to enhance adhesion between the elastic layer 55a and the insulating layer 55b. The adhesive layer may be made of a material such as TiO X , AlO X , CrO XThe thickness of the adhesive layer is determined depending on the thickness and width of the diaphragm 55, and is not particularly limited, but is, for example, in the range of 20 nm to 2000 nm.

[0048] The elastic layer 55a and insulating layer 55b are obtained by being deposited in this order on a silicon single crystal substrate for forming the pressure chamber substrate 52. For example, if the elastic layer 55a is made of silicon oxide, the elastic layer 55a is formed by thermally oxidizing one surface of the silicon single crystal substrate. For example, if the insulating layer 55b is made of zirconium oxide, the insulating layer 55b is formed by forming a zirconium layer on the elastic layer 55a by a sputtering method and then thermally oxidizing the layer.

[0049] The method for forming each of the multiple films constituting diaphragm 55 is not limited to the above-described example, and may be any method. For example, at least a portion of elastic layer 55a may be formed using a chemical vapor deposition (CVD) method or the like. When an adhesive layer is provided between elastic layer 55a and insulating layer 55b, the adhesive layer is formed by forming a layer of chromium, titanium, aluminum, or the like on elastic layer 55a by a sputtering method and then thermally oxidizing the layer. In this case, the thermal oxidation for forming the adhesive layer may be performed simultaneously with the thermal oxidation for forming insulating layer 55b. The method for forming the adhesive layer is not limited to the method using thermal oxidation, and may be, for example, a CVD method or an atomic layer deposition (ALD) method.

[0050] The actuator 1, which is made up of the diaphragm 55 and piezoelectric element 56, has a vibration region PV that vibrates when driven by the piezoelectric element 56. The vibration region PV is a part of the actuator 1, and is a portion that overlaps with the pressure chamber C in a plan view.

[0051] The vibration region PV is divided into an active portion RA and a non-active portion RN. The active portion RA is a portion of the actuator 1 that overlaps with the pressure chamber C, the first electrode 56a, the piezoelectric layer 56b, and the second electrode 56c when viewed along the Z axis. The non-active portion RN is a portion of the actuator 1 that overlaps with the pressure chamber C when viewed along the Z axis, and is a portion different from the active portion RA.

[0052] Hereinafter, the region corresponding to the active portion RA in the direction along the Z axis is referred to as the first region RE1. That is, the first region RE1 is the region where the first electrode 56a, the piezoelectric layer 56b, and the second electrode 56c overlap in the stacking direction DL. Also, the region where the first electrode 56a overlaps with the diaphragm 55 without overlapping with the piezoelectric layer 56b and the second electrode 56c in the stacking direction DL is referred to as the second region RE2. The second region RE2 is included in the region corresponding to the non-active portion RN in the direction along the Z axis. Here, since the first electrode 56a is a common electrode as described above, it is disposed across the first region RE1 and the second region RE2.

[0053] Fig. 6 is an enlarged view of a portion Q in Fig. 5. In addition to the first electrode 56a, piezoelectric layer 56b, and second electrode 56c described above, the piezoelectric element 56 also has a first mixed layer 56d, a second mixed layer 56e, a third mixed layer 56f, and a protective layer 56g, as shown in Fig. 6.

[0054] The first mixed layer 56d is provided on the first electrode 56a in the second region RE2 and is a layer made of a mixed material containing lead and the material constituting the first electrode 56a. In the example shown in FIG. 6, the first mixed layer 56d is provided in the second region RE2. Specifically, the first mixed layer 56d is provided in a portion of the second region RE2, and the end of the first mixed layer 56d on the first region RE1 side coincides with the end of the second region RE2 on the first region RE1 side. Note that for convenience of explanation, FIG. 6 clearly shows the interface between the first mixed layer 56d and the first electrode 56a, but the interface does not have to be clear. For example, the mixing ratio of the mixed material may gradually change in the thickness direction. Furthermore, the first mixed layer 56d may be provided over the entire second region RE2, or may be provided in a position overlapping the partition wall 52b in a plan view.

[0055] The first mixed layer 56d containing lead makes it more difficult for lead in the piezoelectric layer 56b to diffuse toward the second region RE2 or the first electrode 56a located further in the Y1 direction than the second region RE2, compared to a configuration that does not contain lead. Therefore, by providing the first mixed layer 56d on the first electrode 56a in the second region RE2, diffusion of lead from the piezoelectric layer 56b before patterning to the first electrode 56a in the second region RE2 during formation of the piezoelectric layer 56b can be suppressed. Furthermore, diffusion of lead from the end in the width direction of the piezoelectric layer 56b after patterning toward the first electrode 56a in the second region RE2 can be suppressed. In particular, by aligning the end of the first mixed layer 56d on the first region RE1 side with the end of the second region RE2 on the first region RE1 side, diffusion of lead from the piezoelectric layer 56b to the first electrode 56a is effectively prevented.

[0056] Here, the mixed material constituting the first mixed layer 56d contains, for example, lead and at least one of platinum, iridium (Ir), and titanium (Ti), which are materials constituting the first electrode 56d, as an alloy, oxide, nitride, or oxynitride. The formation of such a first mixed layer 56d is not particularly limited, but may be performed, for example, using a film formation method such as ion plating after the formation of the first electrode 56a. The mixed material constituting the first mixed layer 56d may also contain elements other than the material constituting the first electrode 56a.

[0057] The first mixed layer 56d contains constituent elements of the material constituting the third mixed layer 56f, which functions as an adhesive layer as described below. This allows a compound of lead and the material constituting the third mixed layer 56f to be formed in the first mixed layer 56d. As a result, the diffusion of lead from the piezoelectric layer 56b to the first electrode 56a in the first region RE1 can be more effectively suppressed.

[0058] The first mixed layer 56d preferably contains oxidized constituent elements of the material constituting the third mixed layer 56f, which functions as an adhesive layer as described below. That is, the first mixed layer 56d preferably contains oxides of the constituent elements of the material constituting the third mixed layer 56f. This can prevent oxygen from escaping from the piezoelectric layer 56b to the first mixed layer 56d.

[0059] Here, when the third mixed layer 56f contains titanium and titanium oxide and the first mixed layer 56d contains titanium and titanium oxide, the titanium and titanium oxide content of the first mixed layer 56d in the second region RE2 is preferably higher than the titanium and titanium oxide content of the third mixed layer 56f in the first region RE1. Furthermore, it is even more preferable that the titanium oxide content of the first mixed layer 56d in the second region RE2 is higher than the titanium oxide content of the third mixed layer 56f in the first region RE1. This makes it possible to suitably suppress oxygen leakage from the piezoelectric layer 56b to the first mixed layer 56d.

[0060] The content of titanium and titanium oxide in the first mixed layer 56d and the third mixed layer 56f is measured by, for example, secondary ion mass spectrometry. 2 The titanium content and oxygen content in the first mixed layer 56d and the third mixed layer 56f are measured over the range of 1000 to 10000 at each measurement, and the titanium content is normalized by the oxygen content.

[0061] The lead content of the first mixed layer 56d is preferably higher than the lead content of the first electrode 56a in the second region RE2. The lead content of the first mixed layer 56d is also preferably higher than the lead content of the piezoelectric layer 56b. The lead content is measured, for example, by secondary ion mass spectrometry, for an area of ​​1 mm in a plan view. 2The lead content and oxygen content are measured at each measurement over this range, and the lead content is normalized by the oxygen content to calculate the lead content. In this case, the lead content of the first mixed layer 56d is preferably in the range of 30 atm% to 70 atm%, and more preferably in the range of 40 atm% to 60 atm%. The lead content may also be measured by other methods, such as energy dispersive X-ray analysis.

[0062] The thickness t1 of the first mixed layer 56d is preferably 1 / 2000 to 1 / 2 of the thickness T of the first electrode 56a, which makes it possible to suppress the diffusion of lead into the first electrode 56a in the second region RE2 and also to suppress an increase in the electrical resistance of the first electrode 56a caused by the first mixed layer 56d.

[0063] The thickness t1 of the first mixed layer 56d is, for example, in the range of 0.1 nm to 50 nm. Here, the first mixed layer 56d may be a dense layer or a sparse layer in which the mixed material is scattered like islands.

[0064] The second mixed layer 56e is provided between the first electrode 56a and the diaphragm 55 in the second region RE2 and is made of a mixed material containing lead and the material constituting the first electrode 56a. This improves adhesion between the diaphragm 55 and the first electrode 56a. In the example shown in FIG. 6, the second mixed layer 56e is provided between the first electrode 56a and the diaphragm 55 not only in the second region RE2 but also in the first region RE1. That is, the second mixed layer 56e is provided between the first electrode 56a and the diaphragm 55 across the first region RE1 and the second region RE2. The end of the second mixed layer 56e in the Y-axis direction is located within the second region RE2. Note that for convenience of explanation, FIG. 6 clearly shows the interfaces between the second mixed layer 56e and the first electrode 56a and the insulating layer 55b. However, the interfaces do not have to be clear. For example, the mixing ratio of the mixed material may gradually change in the thickness direction. The end of the second mixed layer 56e in the Y-axis direction may coincide with the end of the second region RE2 opposite to the first region RE1 side, or may overlap the partition wall 52b in plan view. Furthermore, the portion of the second mixed layer 56e in the first region RE1 may be provided as needed or may be omitted.

[0065] Here, like the first mixed layer 56d, the mixed material constituting the second mixed layer 56e contains, for example, lead and at least one of platinum (Pt), iridium (Ir), and titanium (Ti), which are materials constituting the first electrode 6d, as an alloy, oxide, nitride, or oxynitride. The formation of such a second mixed layer 56e is not particularly limited, but may be performed, for example, using a film formation method such as ion plating after the formation of the diaphragm 55. The mixed material constituting the second mixed layer 56e may also contain elements other than the material constituting the first electrode 56a.

[0066] The thickness t2 of the second mixed layer 56e is preferably greater than the thickness t1 of the first mixed layer 56d. In other words, the thickness t1 of the first mixed layer 56d is preferably less than the thickness t2 of the second mixed layer 56e. The first mixed layer 56d and the second mixed layer 56e contain lead. A high lead content increases the electrical resistance within the layer, causing a drop in voltage across the piezoelectric layer 56b. In this configuration, the first mixed layer 56b on the piezoelectric side 56b is thinner than the second mixed layer 56e, thereby reducing the electrical resistance of the portion of the first electrode 56a on the piezoelectric layer 56b side. As a result, the drop in voltage across the piezoelectric layer 56b between the first electrode 56a and the second electrode 56c can be reduced.

[0067] In the first region RE1, a layer made of a metal such as platinum exists between the third mixed layer 56f and the second mixed layer 56e in the first electrode 56a, so a slight increase in the thickness of the second mixed layer 56e does not pose a significant problem. Furthermore, because the second mixed layer 56e is disposed on the opposite side of the first electrode 56a from the piezoelectric layer 56b, the presence of the second mixed layer 56e makes it difficult for a drop in the voltage applied to the piezoelectric layer 56b to occur between the first electrode 56a and the second electrode 56c.

[0068] The thickness t2 of the second mixed layer 56e is, for example, in the range of 1 nm to 100 nm. Here, the second mixed layer 56e may be a dense layer or a sparse layer in which the mixed material is scattered like islands.

[0069] The third mixed layer 56f is provided on the first electrode 56a in the first region RE1 and is made of a mixed material containing lead and the material constituting the first electrode 56a. This improves adhesion between the piezoelectric layer 56b and the first electrode 56a. For ease of explanation, Fig. 6 clearly shows the interfaces between the third mixed layer 56f and the first electrode 56a and between the third mixed layer 56f and the first electrode 56a and the piezoelectric layer 56b. However, the interfaces do not have to be clear. For example, the mixing ratio of the mixed material may gradually change in the thickness direction.

[0070] Here, like the first mixed layer 56d, the mixed material constituting the third mixed layer 56f contains, for example, lead and at least one of platinum (Pt), iridium (Ir), and titanium (Ti) as an alloy, oxide, nitride, or oxynitride. In particular, the third mixed layer 56f also functions as an adhesion layer by containing Ti (titanium). The formation of such a third mixed layer 56f is not particularly limited, but may be performed, for example, using a film formation method such as ion plating after the formation of the first electrode 56a. The mixed material constituting the third mixed layer 56f may also contain elements other than the material constituting the first electrode 56a.

[0071] The thickness t3 of the third mixed layer 56f is preferably thicker than the thickness t1 of the first mixed layer 56d. In other words, the thickness t1 of the first mixed layer 56d is preferably thinner than the thickness t3 of the third mixed layer 56f. This can suppress an increase in the electrical resistance of the first electrode 56a in the second region RE2.

[0072] The thickness t3 of the third mixed layer 56f is, for example, in the range of 0.2 nm to 100 nm. Here, the third mixed layer 56f may be a dense layer or a sparse layer in which the mixed material is scattered like islands.

[0073] The protective layer 56g is a layer that covers the laminated body that is made up of the first electrode 56a, the piezoelectric layer 56b, and the second electrode 56c, and protects the laminated body. The protective layer 56g is made of, for example, Al2O3, TaO X , IrO X or TiO X The protective layer 56g is made of a metal oxide such as, for example, but is not particularly limited to, formed by using a film forming method such as chemical vapor deposition (CVD) after the formation of the laminate.

[0074] Here, the portion of the protective layer 56g provided on the first mixed layer 56d in the stacking direction DL functions as a lead diffusion suppression layer that suppresses the diffusion of lead from the first mixed layer 56d to the first electrode 56a.

[0075] The thickness of the protective layer 56g is not particularly limited, but is, for example, in the range of 20 nm to 50 nm.

[0076] 2. Variations Each of the above-mentioned exemplary embodiments can be modified in various ways. Specific modified embodiments that can be applied to each of the above-mentioned embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples can be appropriately combined within the scope of not contradicting each other.

[0077] 2-1. Variation 1 In the above-described embodiment, an example is given in which the second mixed layer 56e, the third mixed layer 56f, and the protective layer 56g are used, but this is not limited to this example, and at least one of the second mixed layer 56e, the third mixed layer 56f, and the protective layer 56g may be omitted.

[0078] 2-2. Variation 2 In each of the above-described embodiments, the piezoelectric layer 56b is provided in common to a plurality of pressure chambers C, but this is not limitative. The piezoelectric layer 56b may be divided for each pressure chamber C.

[0079] 2-3. Variation 3 In each of the above-mentioned embodiments, a serial-type liquid ejection device 100 is exemplified, in which a carriage 41 carrying a liquid ejection head 50 moves back and forth, but the present disclosure can also be applied to a line-type liquid ejection device in which multiple nozzles N are distributed across the entire width of the medium M.

[0080] 2-4. Variation 4 The liquid ejection device 100 exemplified in each of the above-described embodiments can be employed in various devices, such as facsimile machines and copiers, as well as devices dedicated to printing. However, the use of the liquid ejection device of the present disclosure is not limited to printing. For example, a liquid ejection device that ejects a solution of a color material is used as a manufacturing device for forming color filters for liquid crystal display devices. Furthermore, a liquid ejection device that ejects a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring board.

[0081] 3. Summary of this disclosure A summary of this disclosure is provided below.

[0082] (Appendix 1) A first aspect, which is a preferred example of a liquid ejection head of the present disclosure, comprises a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode, and a vibration plate connected to the piezoelectric element, wherein the first electrode, the piezoelectric layer, and the second electrode are stacked in this order in a stacking direction that is a direction from the vibration plate toward the piezoelectric element, and when, in the stacking direction, a region where the first electrode, the piezoelectric layer, and the second electrode overlap is defined as a first region, and a region where the first electrode overlaps the vibration plate without overlapping the piezoelectric layer and the second electrode is defined as a second region, the first electrode is arranged across the first region and the second region, and a first mixed layer made of a mixed material containing lead and the material that constitutes the first electrode is provided on the first electrode in the second region.

[0083] In the above aspect, by providing the first mixed layer on the first electrode in the second region, it is possible to suppress lead diffusion from the piezoelectric layer before patterning to the first electrode in the second region during formation of the piezoelectric layer, and also to suppress lead diffusion from the end in the width direction of the piezoelectric layer after patterning toward the second region or the first electrode outside the second region.

[0084] (Note 2) In a second aspect, which is a preferred example of the first aspect, an adhesive layer is further provided between the first electrode and the piezoelectric layer in the stacking direction, and the first mixed layer contains constituent elements of the material that constitutes the adhesive layer. In the above aspect, a compound between lead and the material that constitutes the adhesive layer can be formed in the first mixed layer. As a result, diffusion of lead from the piezoelectric layer to the first electrode in the first region can be more effectively suppressed.

[0085] (Note 3) In the third aspect, which is a preferred example of the second aspect, the first mixed layer contains an oxide of a constituent element of the material that constitutes the adhesion layer. In this aspect, oxygen leakage from the piezoelectric layer to the first mixed layer can be suppressed.

[0086] (Note 4) In a fourth aspect, which is a preferred example of any of the first to third aspects, a lead diffusion suppression layer that suppresses lead diffusion is provided on the first mixed layer in the stacking direction. In this aspect, lead diffusion from the first mixed layer to the first electrode can be suppressed.

[0087] (Supplementary Note 5) In a fifth aspect, which is a preferred example of any of the first to fourth aspects, a second mixed layer made of a mixed material containing lead and a material constituting the first electrode is provided between the first electrode and the diaphragm in the second region. In the above aspect, it is possible to improve adhesion between the diaphragm and the first electrode.

[0088] (Note 6) In the sixth aspect, which is a preferred example of the fifth aspect, the thickness of the first mixed layer is thinner than the thickness of the second mixed layer. In this aspect, the electrical resistance of the portion of the first electrode on the piezoelectric layer side can be reduced. As a result, the drop in voltage applied to the piezoelectric layer between the first electrode and the second electrode can be suppressed.

[0089] (Supplementary Note 7) In a seventh aspect, which is a preferred example of any of the first to sixth aspects, a third mixed layer made of a mixed material containing lead and a material constituting the first electrode is provided on the first electrode in the first region, and the thickness of the first mixed layer is thinner than the thickness of the third mixed layer. In the above aspects, by providing the third mixed layer on the first electrode in the first region, it is possible to improve adhesion between the piezoelectric layer and the first electrode. Furthermore, by making the thickness of the first mixed layer thinner than the thickness of the third mixed layer, it is possible to suppress an increase in the electrical resistance of the first electrode in the second region.

[0090] (Appendix 8) In an eighth aspect, which is a preferred example of any of the first to seventh aspects, the thickness of the first mixed layer is 1 / 2000 to 1 / 2 of the thickness of the first electrode. In this aspect, it is possible to suppress the diffusion of lead into the first electrode in the second region while suppressing an increase in the electrical resistance of the first electrode caused by the first mixed layer. [Explanation of symbols]

[0091] 1...actuator, 10...liquid container, 20...control unit, 30...transport mechanism, 40...movement mechanism, 41...carriage, 42...transport belt, 50...liquid ejection head, 51...flow path substrate, 52...pressure chamber substrate, 52a...hole, 52b...partition wall, 53...nozzle plate, 54...vibration absorber, 55...vibration plate, 55a...elastic layer, 55b...insulating layer, 56...piezoelectric element, 56a...first electrode, 56b...piezoelectric layer, 56b1...through hole, 56c...second electrode, 56d...first mixed layer, 56e...second mixed composite layer, 56f...third composite layer (adhesion layer), 56g...protective layer, 57...sealing plate, 58...case, 59...wiring board, 60...drive circuit, 100...liquid ejection device, C...pressure chamber, DL...stacking direction, IH...inlet, M...medium, N...nozzle, Na...communicating flow path, PV...vibration area, Q...part, R...liquid storage chamber, R1...opening, R2...accommodation section, RA...active section, RE1...first region, RE2...second region, RN...non-active section, Ra...supply flow path, T...thickness, t1...thickness, t2...thickness, t3...thickness.

Claims

1. a piezoelectric element having a first electrode, a piezoelectric layer, and a second electrode; a vibration plate connected to the piezoelectric element, the first electrode, the piezoelectric layer, and the second electrode are stacked in this order in a stacking direction that is a direction from the vibration plate toward the piezoelectric element, When viewed in the stacking direction, a region where the first electrode, the piezoelectric layer, and the second electrode overlap is defined as a first region, and a region where the first electrode overlaps the vibration plate without overlapping the piezoelectric layer and the second electrode is defined as a second region, the first electrode is disposed across the first region and the second region; a first mixed layer made of a mixed material containing lead and a material constituting the first electrode is provided in the second region on the first electrode; A liquid ejection head characterized by:

2. an adhesive layer disposed between the first electrode and the piezoelectric layer in the stacking direction, the first mixed layer contains constituent elements of the material that constitutes the adhesion layer; The liquid ejection head according to claim 1 .

3. the first mixed layer contains an oxide of a constituent element of the material constituting the adhesion layer; The liquid ejection head according to claim 2 .

4. a lead diffusion suppression layer that suppresses lead diffusion is provided on the first mixed layer in the stacking direction; The liquid ejection head according to claim 1 .

5. In the second region, a second mixed layer made of a mixed material containing lead and a material constituting the first electrode is provided between the first electrode and the diaphragm. The liquid ejection head according to claim 1 .

6. The thickness of the first mixed layer is thinner than the thickness of the second mixed layer. The liquid ejection head according to claim 5 .

7. In the first region, a third mixed layer is provided on the first electrode, the third mixed layer being made of a mixed material containing lead and a material constituting the first electrode, The thickness of the first mixed layer is thinner than the thickness of the third mixed layer. The liquid ejection head according to claim 1 .

8. the thickness of the first mixed layer is 1 / 2000 or more and 1 / 2 or less of the thickness of the first electrode; The liquid ejection head according to claim 1 .

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