Liquid dispensing head and liquid dispensing device

Abstract

To suppress the deterioration of the liquid dispensing characteristics of the liquid dispensing head. [Solution] The liquid discharge head is constructed by stacking a pressure chamber substrate on which a plurality of pressure chambers are arranged in the direction of arrangement, a diaphragm, a first common electrode provided in common to the plurality of pressure chambers to which a reference voltage that does not change over time is applied, a first thin-film piezoelectric body, first individual electrodes provided individually to the plurality of pressure chambers so as to extend in the direction of extension to which a drive voltage that changes over time is applied, an insulating layer, second individual electrodes provided individually to the plurality of pressure chambers so as to extend in the direction of extension to which a drive voltage that changes over time is applied, a second thin-film piezoelectric body, and a second common electrode provided in common to the plurality of pressure chambers to which a reference voltage is applied, in this order from bottom to top along the stacking direction, and the first and second individual electrodes are separated by the insulating layer in the region where the first and second individual electrodes overlap with the pressure chambers when viewed from the stacking direction.

Description

[Technical Field]

[0001] This invention relates to a liquid dispensing head and a liquid dispensing device. [Background technology]

[0002] Liquid ejection devices equipped with a liquid ejection head that ejects liquids such as ink onto a medium such as printing paper have been proposed for some time. Piezo-type inkjet printers are known as such liquid ejection devices. In the piezo type, a piezoelectric element is used to vibrate a diaphragm that forms part of the wall surface of the pressure chamber. By vibrating the diaphragm with the piezoelectric element, the liquid filled in the pressure chamber is ejected from the nozzle.

[0003] In the piezoelectric element of the liquid discharge head described in Patent Document 1, a first common electrode, a thin film lower piezoelectric layer, individual electrodes, a thin film upper piezoelectric layer, and a second common electrode are stacked in that order. In other words, the piezoelectric element has a configuration in which two thin film piezoelectric materials are stacked. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-256137 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the discharge characteristics of the liquid discharge head described above sometimes deteriorated. [Means for solving the problem]

[0006] A liquid discharge head according to a preferred embodiment of the present disclosure comprises a pressure chamber substrate on which a plurality of pressure chambers are arranged in a row in the direction of arrangement; a diaphragm; a first common electrode provided in common to the plurality of pressure chambers to which a reference voltage that does not change over time is applied; a first thin-film piezoelectric material; first individual electrodes provided individually to the plurality of pressure chambers so as to extend in an extending direction intersecting the row of arrangement directions to which a drive voltage that changes over time is applied; an insulating layer; second individual electrodes provided individually to the plurality of pressure chambers so as to extend in the extending direction to which a drive voltage that changes over time is applied; a second thin-film piezoelectric material; and a second common electrode provided in common to the plurality of pressure chambers to which the reference voltage is applied; all of these are stacked in this order from bottom to top along a stacking direction intersecting the row of arrangement directions and the extending direction, and the first individual electrodes and the second individual electrodes are separated by the insulating layer in a first region where the first individual electrodes and the second individual electrodes overlap with the pressure chambers when viewed from the stacking direction.

[0007] Furthermore, a liquid dispensing device according to a preferred embodiment of the present disclosure comprises a liquid dispensing head and a control unit that controls the dispensing operation from the liquid dispensing head. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram showing the liquid dispensing device 100 according to the first embodiment. [Figure 2] Figure 1 shows an exploded perspective view of the liquid discharge head 1. [Figure 3] Figure 2 shows a cross-sectional view of a part of the liquid discharge head 1, specifically the cross-sectional view along line III-III in Figure 2. [Figure 4] A cross-sectional view of a portion of the liquid discharge head 1 shown in Figure 2. [Figure 5] Figure 3 shows an enlarged cross-sectional view of the liquid discharge head 1 region AR. [Figure 6] A diagram showing the planar arrangement of the individual electrodes 7D and the common electrode 7C. [Figure 7] A diagram illustrating the drive voltage Com and the reference voltage VBS. [Figure 8] Figure showing an example of the applied voltage Ea applied to the two thin film piezoelectric elements 7P. [Figure 9] Figure showing a flow chart of the manufacturing method of part of the piezoelectric element 7 of the manufacturing method of the liquid ejection head 1. [Figure 10] Partial cross-sectional view of the liquid ejection head 1a in the second embodiment. [Figure 11] Figure showing a flow chart of the manufacturing method of the piezoelectric element 7a. [Figure 12] Partial cross-sectional view of the liquid ejection head 1b in the first modification. [Figure 13] Equivalent circuit diagram showing the configuration of the piezoelectric element 7a. [Figure 14] Partial cross-sectional view of the liquid ejection head 1c in the fifth modification.

Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments according to the present disclosure will be described while referring to the accompanying drawings. In the drawings, the dimensions or scales of each part are appropriately different from the actual ones, and there are also parts schematically shown for easy understanding. Further, the scope of the present disclosure is not limited to these embodiments unless there is a description to specifically limit the present disclosure in the following description. Note that "equal" includes cases where there are differences on the order of measurement errors in addition to cases where they are exactly equal. Also, "element α and element β are laminated" means that element α and element β may be arranged in the vertical direction, and it does not matter whether element α and element β are in direct contact.

[0010] The following explanation will use the X, Y, and Z axes intersecting each other as appropriate. One direction along the X axis is called the X1 direction, and the direction opposite to the X1 direction is called the X2 direction. Opposite directions along the Y axis are called the Y1 and Y2 directions. Opposite directions along the Z axis are called the Z1 and Z2 directions. Viewing along the Z axis is called a "plan view". The Z axis is typically a vertical axis. The Z1 direction is upward, and the Z2 direction is downward. However, the Z axis does not have to be a vertical axis. Also, the X, Y, and Z axes are typically orthogonal to each other, but are not limited to this; for example, they can intersect at an angle within the range of 80° to 100°.

[0011] 1. First Embodiment 1-1. Overall configuration of the liquid dispensing device 100 Figure 1 is a schematic diagram showing a liquid dispensing device 100 according to the first embodiment. The liquid dispensing device 100 is an inkjet printing device that dispenses ink, which is 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 any material to be printed on, such as a resin film or a cloth.

[0012] As shown in Figure 1, the liquid dispensing device 100 is equipped with a liquid container 90 for storing ink. Specific examples of the liquid container 90 include a cartridge that can be attached to or detached from the liquid dispensing device 100, a bag-shaped ink pack made of a flexible film, and an ink tank that can be refilled with ink. The type of ink stored in the liquid container 90 is arbitrary.

[0013] The liquid dispensing device 100 includes a control unit 91, a transport mechanism 92, a moving mechanism 93, and a liquid dispensing head 1. The control unit 91 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls the dispensing operation from the liquid dispensing head 1. The control unit 91 includes a voltage application circuit 910 that dispenses ink from the nozzle N by controlling the drive of a piezoelectric element 7, which will be described later. The voltage application circuit 910 applies a reference voltage VBS and a drive voltage Com, which will be described later, to the piezoelectric element 7. In this embodiment, unless otherwise specified, when defining a voltage difference, the difference between the voltage at the bottom of the piezoelectric element and the voltage at the top of the piezoelectric element is described as the "voltage difference". Note that the control unit 91 is an example of a "control unit".

[0014] The transport mechanism 92 transports the medium M in the Y2 direction under the control of the control unit 91. The moving mechanism 93 reciprocates the liquid discharge head 1 in the X1 and X2 directions under the control of the control unit 91. In the example shown in Figure 1, the moving mechanism 93 has a roughly box-shaped transport body 931 called a carriage that houses the liquid discharge head 1, and a transport belt 932 to which the transport body 931 is fixed. The number of liquid discharge heads 1 mounted on the transport body 931 is not limited to one, but may be multiple. In addition to the liquid discharge heads 1, a liquid container 90 may also be mounted on the transport body 931.

[0015] The liquid discharge head 1, under the control of the control unit 91, discharges ink supplied from the liquid container 90 onto the medium M from each of the multiple nozzles N in the Z2 direction. This discharge is performed in parallel with the transport of the medium M by the transport mechanism 92 and the reciprocating movement of the liquid discharge head 1 by the moving mechanism 93, thereby forming an image of ink on the surface of the medium M.

[0016] The liquid ejection device 100 includes a liquid ejection head 1 (described later) and a control unit 91. The control unit 91 includes a voltage application circuit 910 that ejects ink from the nozzle N.

[0017] 1-2. Overall configuration of the liquid dispensing head Figure 2 is an exploded perspective view of the liquid discharge head 1 shown in Figure 1. Figure 3 is a cross-sectional view of a part of the liquid discharge head 1 shown in Figure 2, specifically the cross-sectional view taken along line III-III in Figure 2. As shown in Figure 2, the liquid discharge head 1 has a plurality of nozzles N arranged in the direction along the Y axis. In the example shown in Figure 2, the plurality of nozzles N are divided into a first row L1 and a second row L2, which are spaced apart from each other in the direction along the X axis. Each of the first row L1 and the second row L2 is a set of a plurality of nozzles N arranged linearly in the direction along the Y axis. The elements associated with each nozzle N in the first row L1 and the elements associated with each nozzle N in the second row L2 of the liquid discharge head 1 are approximately symmetrical with respect to the direction along the X axis. In the following description, the elements corresponding to the first row L1 will be described in detail, and the description of the elements corresponding to the second row L2 will be omitted as appropriate.

[0018] The positions of the multiple nozzles N in the first row L1 and the multiple nozzles N in the second row L2 along the Y-axis may coincide or differ. Furthermore, elements related to each nozzle N in either the first row L1 or the second row L2 may be omitted.

[0019] As shown in Figures 2 and 3, the liquid discharge head 1 includes a nozzle plate 11, a vibration absorber 12, a flow path substrate 13, a pressure chamber substrate 14, a diaphragm 15, a wiring substrate 16, a housing 17, and a drive circuit 20. Each of the nozzle plate 11, vibration absorber 12, flow path substrate 13, pressure chamber substrate 14, diaphragm 15, wiring substrate 16, and housing 17 is a long, plate-shaped member in the direction along the Y axis. The nozzle plate 11, flow path substrate 13, pressure chamber substrate 14, diaphragm 15, and wiring substrate 16 are arranged in this order in the Z1 direction.

[0020] The nozzle plate 11 is a plate-shaped member on which a plurality of nozzles N are formed. Each of the plurality of nozzles N is a circular through-hole through which ink passes. The nozzles N eject ink by the vibration of the diaphragm 15. The nozzle plate 11 is joined to the flow path substrate 13, for example, by adhesive.

[0021] The flow channel substrate 13 has flow channels formed therein for supplying ink to multiple nozzles N. Specifically, the flow channel substrate 13 has a space Ra, multiple supply channels 131, multiple communication channels 132, and a supply liquid chamber 133. Space Ra is an elongated opening extending in the direction along the Y axis when viewed in a plan view along the Z axis. Each of the supply channels 131 and communication channels 132 is a through-hole formed for each nozzle N. The supply liquid chamber 133 is an elongated space extending in the direction along the Y axis across multiple nozzles N, and connects space Ra and the multiple supply channels 131 to each other. Each of the multiple communication channels 132 overlaps in a plan view with one nozzle N corresponding to that communication channel 132. The pressure chamber substrate 14 is joined to the flow channel substrate 13, for example, by adhesive.

[0022] Multiple pressure chambers C are provided in the pressure chamber substrate 14. The multiple pressure chambers C are arranged in a direction along the Y axis. Each pressure chamber C is formed for each nozzle N and is a long, elongated space that extends in a direction along the X axis in a plan view. The pressure chamber C is a space located between the flow path substrate 13 and the diaphragm 15. The pressure chamber C communicates with the nozzle N via the communication flow path 132 and also communicates with space Ra via the supply flow path 131 and the supply liquid chamber 133. The direction along the Y axis in which the multiple pressure chambers C are arranged is an example of an "arrangement direction".

[0023] The nozzle plate 11, the flow channel substrate 13, and the pressure chamber substrate 14 are each manufactured by processing a silicon single crystal substrate using, for example, dry etching or wet etching. However, other known methods may be used as appropriate for the manufacture of the nozzle plate 11, the flow channel substrate 13, and the pressure chamber substrate 14.

[0024] A diaphragm 15 is positioned on the surface of the pressure chamber substrate 14 facing the Z1 direction. The diaphragm 15 is a plate-shaped member that is elastically vibrable.

[0025] Multiple piezoelectric elements 7, corresponding to nozzles N, are arranged on the surface of the diaphragm 15 facing the Z1 direction. Each piezoelectric element 7 is elongated and extends along the X-axis in a plan view. The multiple piezoelectric elements 7 correspond to multiple pressure chambers C and are arranged along the Y-axis. The piezoelectric elements 7 deform when a voltage is applied. When the diaphragm 15 vibrates in conjunction with this deformation, the pressure in the pressure chambers C fluctuates, causing ink to be ejected from the nozzles N.

[0026] The housing 17 is a case for storing ink supplied to multiple pressure chambers C. As shown in Figure 3, a space Rb is formed in the housing 17. The space Rb in the housing 17 and the space Ra in the flow channel substrate 13 are in communication with each other. The space composed of space Ra and space Rb functions as a liquid storage chamber R, which is a reservoir for storing ink supplied to multiple pressure chambers C. Ink is supplied to the liquid storage chamber R through an inlet 171 formed in the housing 17. The ink in the liquid storage chamber R is supplied to the pressure chambers C via the supply liquid chamber 133 and each supply flow channel 131.

[0027] The vibration absorber 12 is a flexible film that forms the wall surface of the liquid storage chamber R. The vibration absorber 12 is a compliance substrate that absorbs pressure fluctuations of the ink in the liquid storage chamber R.

[0028] As shown in Figure 2, the ends of the external wiring 21 are joined to the surface of the wiring board 16 facing the Z1 direction. The external wiring 21 is composed of connecting components such as FPC (Flexible Printed Circuits) or FFC (Flexible Flat Cable). The wiring board 16 has a plurality of wires 22 that electrically connect the external wiring 21 and the drive circuit 20, and a plurality of wires 23 to which the drive voltage Com and reference voltage VBS output from the drive circuit 20 are supplied.

[0029] Note that the wiring board 16 is not limited to a rigid board, but may also be an FPC (Flexible Printed Circuits) or FFC (Flexible Flat Cable), for example. In this case, the wiring board 16 may also serve as the external wiring 21.

[0030] 1-3. Vibration plate 15 Figure 4 is a cross-sectional view of a portion of the liquid discharge head 1 shown in Figure 2. The cross-sectional view shown in Figure 2 is the cross-section along line IV-IV in Figure 2. Figure 5 is an enlarged cross-sectional view of region AR of the liquid discharge head 1 shown in Figure 3. The diaphragm 15 shown in Figures 4 and 5 vibrates in response to the vibration of the piezoelectric element 7. The diaphragm 15 has, for example, a first layer 151 and a second layer 152. The first layer 151 and the second layer 152 are stacked in this order from bottom to top, i.e., in the Z1 direction.

[0031] The first layer 151 is an elastic film composed of, for example, silicon oxide (SiO2). This elastic film is formed, for example, by thermal oxidation of one side of a silicon single crystal substrate. The second layer 152 is an insulating film composed of, for example, zirconium oxide (ZrO2). This insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer. Zirconium oxide has excellent electrical insulation properties, mechanical strength, and toughness. Therefore, by including the second layer 152 containing zirconium oxide in the diaphragm 15, the characteristics of the diaphragm 15 can be improved.

[0032] Furthermore, other layers, such as metal oxides, may be interposed between the first layer 151 and the second layer 152. Also, part or all of the diaphragm 15 may be integrally formed with the pressure chamber substrate 14. In addition, the diaphragm 15 may be composed of layers of a single material. Figure 4 illustrates the neutral axis A1 of the diaphragm 15 and the piezoelectric element 7. The position of the neutral axis A1 will vary depending on the material and thickness of the diaphragm 15 and the piezoelectric element 7, but in this embodiment, it is set to be located within the diaphragm 15. Since the piezoelectric element 7 is more easily displaced the further it is from the neutral axis A1, arranging the neutral axis A1 below the piezoelectric element 7, i.e., within the diaphragm 15, allows the entire piezoelectric element 7 to be separated from the neutral axis A1 to some extent, thereby increasing the displacement efficiency.

[0033] 1-4. Characteristics of the piezoelectric element 7 To increase the displacement per unit voltage, one can consider a configuration in which a piezoelectric element is formed by sequentially stacking a first common electrode, a first thin-film piezoelectric body, individual electrodes, a second thin-film piezoelectric body, and a second common electrode. Hereinafter, this configuration may be referred to as the "comparative configuration." However, the discharge characteristics of the liquid discharge head in the comparative configuration sometimes deteriorated. Discharge characteristics include, for example, the discharge volume and / or discharge speed. In the liquid discharge head of the comparative configuration, the direction of the electric field generated by the first common electrode and individual electrodes is opposite to the direction of the electric field generated by the individual electrodes and the second common electrode. Therefore, in the first thin-film piezoelectric body, a portion of the electric field generated by the first common electrode and individual electrodes is canceled out by the electric field generated by the individual electrodes and the second common electrode, reducing the deformation of the first thin-film piezoelectric body. Similarly, in the second thin-film piezoelectric body, a portion of the electric field generated by the individual electrodes and the second common electrode is canceled out by the electric field generated by the first common electrode and individual electrodes, reducing the deformation of the second thin-film piezoelectric body. In other words, in the liquid discharge head of the comparative embodiment, a portion of the electric field of one of the two electric fields is canceled out by the electric field of the other, resulting in a decrease in the deformation amount of the two thin-film piezoelectric materials and consequently a decrease in discharge characteristics.

[0034] Therefore, in the piezoelectric element 7 of the first embodiment, the individual electrodes are divided vertically, and an insulating layer 7Z is provided between the divisions, thereby suppressing the cancellation of a portion of the electric field of one of the two electric fields by the electric field of the other.

[0035] 1-5. Piezoelectric element 7 As shown in Figure 3, the piezoelectric element 7 overlaps the aforementioned pressure chamber C in a plan view. As shown in Figures 4 and 5, the piezoelectric element 7 is arranged on the diaphragm 15. The piezoelectric element 7 has a first common electrode 7C1, a first thin-film piezoelectric body 7P1, a first individual electrode 7D1, an insulating layer 7Z, a second individual electrode 7D2, and a second common electrode 7C2. The first common electrode 7C1, the first thin-film piezoelectric body 7P1, the first individual electrode 7D1, the insulating layer 7Z, the second individual electrode 7D2, and the second common electrode 7C2 are stacked in this order from bottom to top. The first common electrode 7C1 and the second common electrode 7C2 are generally common to multiple piezoelectric elements 7. Other layers, such as layers to improve adhesion, may be interposed between the layers of the piezoelectric element 7, or between the piezoelectric element 7 and the diaphragm 15 as appropriate. The direction along the Z-axis, which is the direction in which each element of the piezoelectric element 7 is stacked, is an example of the "stacking direction".

[0036] In the following, the first common electrode 7C1 and the second common electrode 7C2 may be referred to simply as the common electrode 7C without distinction. Similarly, the first thin-film piezoelectric element 7P1 and the second thin-film piezoelectric element 7P2 may be referred to simply as the thin-film piezoelectric element 7P without distinction. Furthermore, the first individual electrode 7D1 and the second individual electrode 7D2 may be referred to simply as the individual electrode 7D.

[0037] In a plan view along the Z-axis, the thin-film piezoelectric element 7P is separated from the multiple piezoelectric elements 7 by through-holes HO (described later) in the area that overlaps with the pressure chamber C. However, in the area that does not overlap with the pressure chamber C, they are connected and constitute a single continuous component. However, the thin-film piezoelectric element 7P does not necessarily have to be a single continuous component.

[0038] 1-5a. Common electrode 7C The common electrode 7C is provided in common for the aforementioned multiple pressure chambers C. The common electrode 7C is a strip-shaped element that extends along the Y-axis so as to be continuous with the multiple pressure chambers C. A reference voltage VBS that does not change over time is applied to the common electrode 7C. As shown in Figure 4, in the direction along the Y-axis, the first common electrode 7C1 and the second common electrode 7C2 are in contact where there is no thin-film piezoelectric element 7P. Therefore, a common voltage is applied to the first common electrode 7C1 and the second common electrode 7C2.

[0039] Examples of materials for the common electrode 7C include metallic materials or alloys such as platinum (Pt), iridium (Ir), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). The common electrode 7C may be a single layer or multiple layers. For example, the common electrode 7C has a laminated structure in which a layer made of platinum is stacked on top of a layer made of iridium.

[0040] 1-5b.Individual electrode 7D Individual electrodes 7D are provided individually for each of the multiple pressure chambers C. A drive voltage Com, which changes over time, is applied to the individual electrodes 7D. In this embodiment, the same drive voltage Com is applied to each of the two individual electrodes 7D.

[0041] Examples of materials for the individual electrodes 7D include metal materials or alloys such as platinum, iridium, aluminum, nickel, gold, and copper. The individual electrodes 7D may be a single layer or multiple layers.

[0042] 1-5c. Thin-film piezoelectric material 7P The thin-film piezoelectric material 7P is composed of a composite oxide. Specifically, the thin-film piezoelectric material 7P is composed of a piezoelectric material having a perovskite crystal structure. Examples of such piezoelectric materials include lead titanate (PbTiO3), lead zirconate titanate (PZT:Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead lanthanum zirconate titanate ((Pb,La)(Zr,Ti)O3), lead zirconium niobate titanate (Pb(Zr,Ti,Nb)O3), and lead zirconium magnesium niobate titanate (Pb(Zr,Ti)(Mg,Nb)O3). Among these, lead zirconate titanate (PZT) is preferably used as the constituent material of the thin-film piezoelectric material. The thin-film piezoelectric material may contain small amounts of other elements such as impurities. Each of the two thin-film piezoelectric elements 7P may be a single layer or multiple layers.

[0043] From another perspective, it is preferable that each of the two thin-film piezoelectric elements 7P is made of the same material. Having both thin-film piezoelectric elements 7P made of the same material simplifies manufacturing and makes it easier to design desired physical properties, for example, simply by controlling the film thickness. However, the two thin-film piezoelectric elements 7P may be formed from different materials.

[0044] Furthermore, each of the two thin-film piezoelectric elements 7P is a thin film. Specifically, the thickness of each of the two thin-film piezoelectric elements 7P is preferably 5 μm or less, and more preferably 2 μm or less. Note that the thicknesses of the two thin-film piezoelectric elements 7P may be the same or different.

[0045] As can be seen from Figures 4 and 5, each of the two thin-film piezoelectric elements 7P is formed to cover a portion of at least one of the electrodes, the first common electrode 7C1 and the two individual electrodes 7D. Specifically, as shown in Figure 5, the first thin-film piezoelectric element 7P1 is formed to cover the first common electrode 7C1 at its end in the X1 direction. As shown in Figure 4, the second thin-film piezoelectric element 7P2 has a parallel portion 7P21 which is parallel to the XY plane and an inclined portion 7P22 which is inclined with respect to the direction along the XY plane and the Z axis. In Figure 4, the designation of reference numerals has been omitted to avoid illustration complexity, but the inclined portion 7P22 is present at both ends of the parallel portion 7P21 in the Y1 and Y2 directions. The end of the inclined portion 7P22 in the Z2 direction is in contact with the first common electrode 7C1. In Figure 4, the second thin-film piezoelectric element 7P2 is formed to cover the first thin-film piezoelectric element 7P1, the first individual electrode 7D1, the insulating layer 7Z, and the second individual electrode 7D2 at its ends in the Y1 and Y2 directions. Therefore, the thickness of each of the two thin-film piezoelectric elements 7P differs in the portion that overlaps with the electrodes and the like and the portion that does not overlap in a plan view. Accordingly, the thinnest thickness TP1 of the first thin-film piezoelectric element 7P1 and the thinnest thickness TP2 of the second thin-film piezoelectric element 7P2, as shown in Figure 4, are preferably 5 μm or less, and more preferably 2 μm or less.

[0046] In the following description, as can be understood from Figure 5, in a plan view, the region of the first individual electrode 7D1 and the second individual electrode 7D2 that overlaps with the pressure chamber C may be described as the active region AAR. On the other hand, in a plan view, of the two regions in which the first individual electrode 7D1 and the second individual electrode 7D2 do not overlap with the pressure chamber C, the region located in the X1 direction of the active region AAR may be described as the inactive region XR1, and the region located in the X2 direction of the active region AAR may be described as the inactive region XR2. Furthermore, as shown in Figure 4, in the direction along the Y axis, of the two regions in the piezoelectric element 7 in which the first individual electrode 7D1 and the second individual electrode 7D2 are not provided, the region located in the Y1 direction may be described as the inactive region YR1, and the region located in the Y2 direction may be described as the inactive region YR2. The active domain AAR is an example of the "first domain," the inactive domains XR1 and XR2 are examples of the "second domain," and the inactive domains YR1 and YR2 are examples of the "third domain."

[0047] As shown in Figure 5, in the connection region XE1 included in the non-active region XR1, the first individual electrode 7D1 and the second individual electrode 7D2 are connected to each other. Therefore, the first individual electrode 7D1 and the second individual electrode 7D2 are at the same potential. Furthermore, in the connection region XE2 included in the non-active region XR2, the first individual electrode 7D1 and the second individual electrode 7D2 are connected to each other.

[0048] Furthermore, as can be seen from Figure 5, in a plan view, the connection region XE1 and the second wiring section 732 overlap. Also, as can be seen from Figure 5, the length of the connection region XE1 in the direction along the X axis is longer than the length of the connection region XE2 in the direction along the X axis. The shorter the length of the non-active regions XR1 and XR2 in the direction along the X axis, the more the liquid discharge head 1 can be miniaturized in the direction along the X axis. However, in order to provide a connection point between the second wiring section 732 and the second individual electrode 7D2, the non-active region XR1 needs to have a certain length. Therefore, in the first embodiment, compared to the embodiment in which the length of the connection region XE1 in the direction along the X axis is shorter than the length of the connection region XE2 in the direction along the X axis, the liquid discharge head 1 can be miniaturized in the direction along the X axis while ensuring a connection point between the second wiring section 732 and the second individual electrode 7D2. However, the length of connection region XE1 along the X-axis may be shorter than the length of connection region XE2 along the X-axis.

[0049] As shown in Figure 4, in the non-active regions YR1 and YR2, the first common electrode 7C1, the second thin-film piezoelectric 7P2, and the second common electrode 7C2 are stacked in that order from bottom to top, and the first thin-film piezoelectric 7P1 and the insulating layer 7Z are not stacked.

[0050] As can be seen from Figure 5, the positions of the ends of the first common electrode 7C1 and the second common electrode 7C2 in the X1 direction on the X axis substantially coincide with the position of the pressure chamber C in the X1 direction on the X axis.

[0051] Figure 6 shows the planar arrangement of the individual electrodes 7D and the common electrode 7C. As shown in Figure 6, each individual electrode 7D is elongated and extends along the X-axis. Multiple individual electrodes 7D are spaced apart from each other and arranged along the Y-axis. As shown in Figure 5, one end of each individual electrode 7D in the longitudinal direction along the X-axis is connected to an individual wiring section 73 for applying the drive voltage Com. The direction along the X-axis in which each individual electrode 7D extends is an example of the "extension direction".

[0052] The individual wiring section 73 includes a first wiring section 731, a second wiring section 732, a third wiring section 733, and a fourth wiring section 734. The first wiring section 731 extends in the direction along the X-axis and is provided above the second thin-film piezoelectric body 7P2. The second wiring section 732 branches off from the X2-direction end of the first wiring section 731, extends in the Z-direction so as to penetrate the second thin-film piezoelectric body 7P2, and connects to the second individual electrode 7D2. Specifically, the second wiring section 732 penetrates the contact hole H1 that penetrates the second thin-film piezoelectric body 7P2. The third wiring section 733 extends in the Z-direction along the X1-direction side of the second thin-film piezoelectric body 7P2 and the first thin-film piezoelectric body 7P1, connects to the first wiring section 731 at its Z1-direction end, and connects to the fourth wiring section 734 at its Z2-direction end. The fourth wiring section 734 is provided on the surface of the diaphragm 15 facing the Z1 direction and is connected to wiring 70 that extends along the Y axis. The wiring 70 is electrically connected to the drive circuit 20 mounted on the wiring board 16 via the aforementioned conductive bumps 16B. As described above, in the connection region XE2, the first individual electrode 7D1 and the second individual electrode 7D2 are connected to each other, so the two individual electrodes 7D are electrically connected to the drive circuit 20 via the individual wiring section 73 and wiring 70.

[0053] A lead wire 750 is connected to the corner of the second common electrode 7C2. The lead wire 750 is electrically connected to the drive circuit 20 mounted on the wiring board 16 via the aforementioned conductive bumps 16B. As described above, there are points of contact between the first common electrode 7C1 and the second common electrode 7C2, so the first common electrode 7C1 and the second common electrode 7C2 are electrically connected to the drive circuit 20 via the lead wire 750.

[0054] 1-5d. Insulating layer 7Z As shown in Figure 5, in the active region AAR, the first individual electrode 7D1 and the second individual electrode 7D2 are separated by an insulating layer 7Z. It is preferable that the insulating layer 7Z is not present in the non-active regions XR1 and XR2, but it may be present. In the example in Figure 5, the insulating layer 7Z is present at the X2 end of the non-active region XR1, and there is no insulating layer in the non-active region XR2. The insulating layer 7Z may be made of any material that is an insulator, for example, a zirconium oxide such as zirconium dioxide (ZrO2). Note that the fact that the insulating layer 7Z is made of zirconium oxide is an example of "the insulating layer containing zirconium." The fact that the insulating layer 7Z contains zirconium means that it contains zirconium atoms.

[0055] The insulating layer 7Z is thinner than the first individual electrode 7D1 and the second individual electrode 7D2. As can be seen from Figure 5, the second individual electrode 7D2 is thickest in connection regions XE1 and XE2, and thinnest in the active region AAR. Therefore, the statement that the insulating layer 7Z is thinner than the first individual electrode 7D1 and the second individual electrode 7D2 means that the insulating layer 7Z is thinner than the active region AAR portion of both the first individual electrode 7D1 and the second individual electrode 7D2. Specifically, as shown in Figures 4 and 5, the thickness TZ of the insulating layer 7Z in the direction along the Z axis is shorter than the thickness TD1 of the first individual electrode 7D1 in the direction along the Z axis and the thickness TD2 of the second individual electrode 7D2 in the direction along the Z axis. Also, thickness TD2 is thinner than thickness TD1. Therefore, the following relationship (1) holds. TZ <TD2<TD1 (1)

[0056] 1-5e. Orientation control layer 7H Although not shown in the diagram, orientation control layers 7H are provided in the active region AAR between the first thin-film piezoelectric element 7P1 and the first common electrode 7C1, and between the second thin-film piezoelectric element 7P2 and the second common electrode 7C2. The orientation control layers 7H control the orientation of the first thin-film piezoelectric element 7P1 and the second thin-film piezoelectric element 7P2, respectively.

[0057] By providing the alignment control layer 7H, the alignment of each of the first thin film piezoelectric body 7P1 and the second thin film piezoelectric body 7P2 can be controlled. As a specific alignment control, the alignment control layer 7H can preferentially align the crystals of the first thin film piezoelectric body 7P1 and the second thin film piezoelectric body 7P2 in a predetermined plane orientation, or adjust the degree of alignment in a predetermined plane orientation. For example, by preferentially aligning the crystals of the first thin film piezoelectric body 7P1 and the second thin film piezoelectric body 7P2 in the (100) plane by the alignment control layer 7H, the piezoelectric characteristics of the piezoelectric element 7 can be improved compared to the case of preferentially aligning the crystals in the (110) plane. Therefore, the displacement efficiency of the piezoelectric element 7 can be increased.

[0058] Also, for example, the alignment control layer 7H can adjust the degree of alignment of the crystals of the first thin film piezoelectric body 7P1 and the second thin film piezoelectric body 7P2 in the (100) plane. Therefore, by providing the alignment control layer 7H for controlling the alignment of the first thin film piezoelectric body 7P1 and the second thin film piezoelectric body 7P2, the second thin film piezoelectric body 7P2 can be set to a desired degree of alignment. Thus, the optimum physical property values can be set for the first thin film piezoelectric body 7P1 and the second thin film piezoelectric body 7P2.

[0059] The alignment control layer 7H includes, for example, titanium (Ti) or a composite oxide having a perovskite structure. The composite oxide having a perovskite structure includes, for example, any of nickel (Ni), lanthanum (La), bismuth (Bi), lead (Pb), titanium (Ti), and iron (Fe) as constituent elements. In the present embodiment, it is preferable that the alignment control layer 7H contains titanium. That the alignment control layer 7H contains titanium means that it contains titanium atoms.

[0060] Specifically, for example, as the composite oxide having a perovskite structure, there are lead titanate (PbTiO3), lanthanum nickelate (LaNiO3), Pb x Bi (a-x) Fe y Ti (b-y) O z 、and Pb x Fe y Ti (1-y) O zinclude. Note that the alignment control layer 7H may be a single layer or multiple layers. Therefore, the material of the alignment control layer 7H may be one type or multiple types.

[0061] In addition, for the aforementioned Pb x Bi (a-x) Fe y Ti (b-y) O z where a > x and b > y. Also, it is preferable that 0.04 < x / (a - x) < 1.40. Furthermore, in order to be oriented in the (100) plane, it is more preferable that x / (a - x) < 0.72. Also, it is preferable that b = 1, and it is preferable that 0.8 < (a / b) < 1.4. Also, it is preferable that z satisfies 2.8 < z < 3.2.

[0062] Examples satisfying these preferable ranges include, for example, a = 1.2, b = 1.0, x = 0.1, y = 0.5.

[0063] In addition, for Pb x Fe y Ti (1-y) O z x satisfies the relationship 1.00 ≦ x < 2.00. In order to be oriented in the (100) plane, it is preferable that x satisfies the relationship 1.00 ≦ x < 1.50. Also, y satisfies the relationship 0.10 ≦ y ≦ 0.90. In order to be oriented in the (100) plane, it is preferable that 0.20 ≦ y ≦ 0.80. Also, typically, z satisfies the relationship z = 3.00. However, z does not necessarily have to satisfy this relationship.

[0064] Note that hereinafter, Pb x Bi (a-x) Fe y Ti(b - y)O z is simply described as "PbBiFeTiO". Pb x Fe y Ti (1-y) O z is simply described as "PbFeTiO".

[0065] For example, the orientation control layer 7H preferably contains Bi, Fe, Ti, and Pb. Specifically, in this case, for example, the orientation control layer 7H is PbBiFeTiO. Compared to PbFeTiO, lanthanum nickelate, and titanium, PbBiFeTiO has superior performance in controlling the orientation of the first thin-film piezoelectric material 7P1 and the second thin-film piezoelectric material 7P2. For this reason, for example, the degree of orientation of the first thin-film piezoelectric material 7P1 and the second thin-film piezoelectric material 7P2 toward the (100) plane can be increased. Therefore, the piezoelectric efficiency of the first thin-film piezoelectric material 7P1 and the second thin-film piezoelectric material 7P2 can be increased.

[0066] 1-6. Operation of the piezoelectric element 7 Figure 7 is a diagram illustrating the driving voltage Com and the reference voltage VBS. In Figure 7, the horizontal axis represents time, and the vertical axis represents voltage [V]. A voltage is applied to the piezoelectric element 7 by the voltage application circuit 910 described above. Specifically, the voltage application circuit 910 applies a voltage to the two thin-film piezoelectric elements 7P through two common electrodes 7C and two individual electrodes 7D. The first thin-film piezoelectric element 7P1 deforms according to the voltage applied between the first common electrode 7C1 and the first individual electrode 7D1. The second thin-film piezoelectric element 7P2 deforms according to the voltage applied between the second individual electrode 7D2 and the second common electrode 7C2.

[0067] A drive voltage Com is applied to each of the two individual electrodes 7D, corresponding to the ink ejection amount. The drive voltage Com changes over time. The drive voltage Com includes a drive waveform WCom. The drive waveform WCom repeats for a unit period Tu. The drive waveform WCom includes an intermediate voltage Ek, a maximum voltage En, and a minimum voltage Em. The maximum voltage En is the maximum value of the drive voltage Com. The minimum voltage Em is the minimum value of the drive voltage Com. The drive waveform WCom decreases from the intermediate voltage Ek to the minimum voltage Em, maintains the minimum voltage Em, then increases from the minimum voltage Em to the maximum voltage En, maintains the maximum voltage En, and then decreases to the intermediate voltage Ek. Note that the drive waveform WCom shown in Figure 7 is just an example, and the drive voltage Com may have other waveforms.

[0068] A constant reference voltage VBS is applied to each of the two common electrodes 7C, regardless of the ink ejection rate. The reference voltage VBS remains constant over time. In the illustrated example, the reference voltage VBS is higher than the minimum voltage Em of the drive voltage Com, but is not limited to this. The reference voltage VBS may also be at GND potential, i.e., 0[V].

[0069] Figure 8 shows an example of the applied voltage Ea applied to the two thin-film piezoelectric elements 7P. The applied voltage Ea shown in Figure 8 is the value obtained by subtracting the reference voltage VBS from the drive voltage Com shown in Figure 7 at each time point.

[0070] When the driving voltage Com and the reference voltage VBS are applied, the difference between the driving voltage Com and the reference voltage VBS is applied to the first thin-film piezoelectric element 7P1 between the first common electrode 7C1 and the first individual electrode 7D1, causing the first thin-film piezoelectric element 7P1 to deform. Similarly, when the driving voltage Com and the reference voltage VBS are applied, the difference between the driving voltage Com and the reference voltage VBS is applied to the second thin-film piezoelectric element 7P2 between the second common electrode 7C2 and the second individual electrode 7D2, causing the second thin-film piezoelectric element 7P2 to deform.

[0071] In Figure 8, the horizontal axis represents time, and the vertical axis represents voltage [V]. The applied voltage Ea includes the waveform WEa. The waveform WEa includes the intermediate voltage EK, the maximum voltage EN, and the minimum voltage EM. The maximum voltage EN is the difference between the maximum voltage En of the drive voltage Com and the reference voltage VBS. The minimum voltage EM is the difference between the minimum voltage Em of the drive voltage Com and the reference voltage VBS. Note that the waveform WEa shown in Figure 8 is an example and will vary depending on the drive voltage Com and the reference voltage VBS.

[0072] Since the reference voltage VBS is constant, the voltage range RE of the applied voltage Ea and the voltage range RE of the drive voltage Com are equal.

[0073] When the maximum voltage EN shown in Figure 8 is applied to the two thin-film piezoelectric elements 7P, the first thin-film piezoelectric element 7P1 is affected by an electric field directed in the Z2 direction. The second thin-film piezoelectric element 7P2 is affected by an electric field directed in the Z1 direction. Thus, although the direction of the electric field affecting the two thin-film piezoelectric elements 7P is different, the magnitude of the electric field is the same.

[0074] The piezoelectric element 7, which includes the two thin-film piezoelectric elements 7P described above, deforms in the Z1 direction during the expansion period T2, when the voltage is reduced from the intermediate voltage EK to the minimum voltage EM as shown in Figure 8, causing the pressure chamber C to expand. In other words, the piezoelectric element 7 deforms upward to expand the pressure chamber C. As a result, ink is drawn into the pressure chamber C. Next, during the contraction period T1, when the voltage is increased from the minimum voltage EM to the maximum voltage EN, causing the pressure chamber C to contract, the piezoelectric element 7 and the diaphragm 15 deform in the Z2 direction. In other words, the piezoelectric element 7 deforms downward to contract the pressure chamber C. As a result, the ink in the pressure chamber C is ejected from the nozzle N.

[0075] 1-7. Manufacturing method of piezoelectric element 7 Figure 9 is a flow chart showing a part of the manufacturing method for the piezoelectric element 7 of the liquid discharge head 1. As shown in Figure 9, the manufacturing method for the piezoelectric element 7 includes the first step S1, the second step S2, the third step S3, the fourth step S4, the sixth step S6, the seventh step S7, the eighth step S8, the ninth step S9, and the tenth step S10. These steps are performed in this order.

[0076] In the first step S1, a first common electrode 7C1 is formed on the diaphragm 15. The first common electrode 7C1 is formed by known film deposition techniques such as vapor deposition or sputtering.

[0077] In the second step S2, an orientation control layer 7H is deposited on the first common electrode 7C1, and then a first thin-film piezoelectric material 7P1 is deposited. The first thin-film piezoelectric material 7P1 is formed, for example, by forming a precursor layer of the first thin-film piezoelectric material 7P1 by the sol-gel method, and then firing the precursor layer to crystallize it. Alternatively, the first thin-film piezoelectric material 7P1 may be formed by the sputtering method. However, by using the sol-gel method, it is possible to suitably form a first thin-film piezoelectric material 7P1 with a thickness of 2 μm or less, and even 1 μm or less.

[0078] In the third step S3, a first individual electrode 7D1 is deposited on the first thin-film piezoelectric body 7P1. The first individual electrode 7D1 is formed by known deposition techniques such as vapor deposition or sputtering.

[0079] In the fourth step S4, an insulating layer 7Z is formed on the first individual electrode 7D1. The insulating layer 7Z is formed by known film formation techniques such as vapor deposition or sputtering.

[0080] In the sixth step S6, a second individual electrode 7D2 is formed on the insulating layer 7Z. The second individual electrode 7D2 is formed by known film formation techniques such as vapor deposition or sputtering.

[0081] In step S7, the first thin-film piezoelectric element 7P1, the first individual electrode 7D1, the insulating layer 7Z, and the second individual electrode 7D2 are patterned. The patterning is performed using known processing techniques such as etching.

[0082] In step S8, an orientation control layer 7H is formed so as to cover the first thin-film piezoelectric 7P1, the first individual electrode 7D1, the insulating layer 7Z, and the second individual electrode 7D2, and then a second thin-film piezoelectric 7P2 is formed. The second thin-film piezoelectric 7P2 is formed by known film formation techniques such as vapor deposition or sputtering.

[0083] In the ninth step, S9, the second thin-film piezoelectric material 7P2 is patterned.

[0084] In the tenth step S10, a second common electrode 7C2 is formed on the second thin-film piezoelectric body 7P2. The second common electrode 7C2 is formed by known film deposition techniques such as vapor deposition and sputtering, and known processing techniques such as photolithography and etching.

[0085] After the completion of the 10th step S10, the piezoelectric element 7 is manufactured by firing it at a high temperature.

[0086] 1-8. Summary of the First Embodiment The liquid discharge head 1 includes a pressure chamber substrate 14 on which multiple pressure chambers C are arranged in a direction along the Y axis, a diaphragm 15, a first common electrode 7C1 provided in common to the multiple pressure chambers C to which a reference voltage VBS that does not change over time is applied, a first thin-film piezoelectric body 7P1, first individual electrodes 7D1 extending in a direction along the X axis and individually provided to the multiple pressure chambers to which a driving voltage Com that changes over time is applied, an insulating layer 7Z, and multiple pressure chambers extending in a direction along the X axis A second individual electrode 7D2 is provided individually for each pressure chamber C, to which a driving voltage Com that changes over time is applied; a second thin-film piezoelectric body 7P2 is provided in common for multiple pressure chambers C, to which a reference voltage VBS is applied; and these are stacked in this order from bottom to top along the Z-axis, with the first individual electrode 7D1 and the second individual electrode 7D2 being separated by an insulating layer 7Z in the active region AAR where the first individual electrode 7D1 and the second individual electrode 7D2 overlap with the pressure chamber C when viewed from the direction along the Z-axis. According to the first embodiment, the insulating layer 7Z suppresses the cancellation of the electric field generated by the first individual electrode 7D1 and the first common electrode 7C1 and the electric field generated by the second individual electrode 7D2 and the second common electrode 7C2, thereby preventing a decrease in the discharge characteristics of the liquid discharge head 1.

[0087] Furthermore, the first individual electrode 7D1 and the second individual electrode 7D2 are connected to each other in the non-active region XR1 where the first individual electrode 7D1 and the second individual electrode 7D2 do not overlap with the pressure chamber C when viewed from a direction along the Z axis. According to the first embodiment, compared to an embodiment in which the first individual electrode 7D1 and the second individual electrode 7D2 are not connected, it is not necessary to prepare wiring to connect the first individual electrode 7D1 and the second individual electrode 7D2, respectively.

[0088] Furthermore, the first individual electrode 7D1 and the second individual electrode 7D2 are connected to each other at both ends in the direction along the X-axis of the first individual electrode 7D1 and the second individual electrode 7D2 within the non-active region XR1 and the non-active region XR2. In the configuration where one end of the first individual electrode 7D1 and the second individual electrode 7D2 are connected along the X-axis, a voltage drop occurs at the unconnected end. When a voltage drop occurs, the voltage applied to the thin-film piezoelectric material 7P decreases, resulting in a decrease in discharge characteristics. Therefore, in the first embodiment, compared to the configuration where one end of the first individual electrode 7D1 and the second individual electrode 7D2 are connected along the X-axis, the occurrence of a voltage drop can be suppressed, thereby suppressing a decrease in discharge characteristics.

[0089] Furthermore, in the non-active regions YR1 and YR2, where the first individual electrode 7D1 and the second individual electrode 7D2 are not provided in the direction along the Y axis, the first common electrode 7C1, the second thin-film piezoelectric element 7P2, and the second common electrode 7C2 are stacked in that order from bottom to top, and the first thin-film piezoelectric element 7P1 and the insulating layer 7Z are not stacked.

[0090] Furthermore, the insulating layer 7Z is thinner than the first individual electrode 7D1 and the second individual electrode 7D2. The insulating layer 7Z should be able to suppress the cancellation of the electric field generated by the first individual electrode 7D1 and the first common electrode 7C1 and the electric field generated by the second individual electrode 7D2 and the second common electrode 7C2. According to the first embodiment, compared to an embodiment in which the insulating layer 7Z is thicker than the first individual electrode 7D1 and the second individual electrode 7D2, the deformation of the piezoelectric element 7 can be suppressed from being hindered by the insulating layer 7Z.

[0091] Furthermore, the second individual electrode 7D2 is thinner than the first individual electrode 7D1. Generally, the flexibility of a laminate is influenced by the distance from the neutral axis of the component. As can be seen from Figure 4, the second individual electrode 7D2 is further from the neutral axis A1 than the first individual electrode 7D1. Therefore, the second thin-film piezoelectric material 7P2 contributes more to the deformation of the entire piezoelectric element 7 than the first thin-film piezoelectric material 7P1. On the other hand, from the perspective of the deformation of the piezoelectric element 7, the two individual electrodes 7D are components that make the piezoelectric element 7 difficult to deform. Therefore, to optimize the deformation of the entire piezoelectric element 7, it is better to make the second individual electrode 7D2, which corresponds to the second thin-film piezoelectric material 7P2 that contributes more, thinner than the first individual electrode 7D1, thereby reducing the degree of inhibition of deformation. Furthermore, an embodiment in which both the first individual electrode 7D1 and the second individual electrode 7D2 are made thin is conceivable. However, in this embodiment, if both the first individual electrode 7D1 and the second individual electrode 7D2 are made thin, the electrical resistance of the first individual electrode 7D1 and the second individual electrode 7D2 becomes too large, and a significant voltage drop occurs from the connection region XE1 to the connection region XE2. In light of this, the first individual electrode 7D1, which corresponds to the first thin-film piezoelectric body 7P1, which has a relatively small contribution to the deformation of the entire piezoelectric element 7, is made relatively thicker. Therefore, according to the first embodiment, it is possible to suppress the occurrence of a voltage drop in the two individual electrodes 7D while maintaining the deformability of the piezoelectric element 7.

[0092] Furthermore, it is preferable that the insulating layer 7Z contains zirconium.

[0093] Furthermore, the liquid dispensing device 100 includes a liquid dispensing head 1 and a control unit 91 that controls the dispensing operation from the liquid dispensing head 1.

[0094] 2. Second Embodiment In the second embodiment, the piezoelectric element 7a in the second embodiment differs in shape from the piezoelectric element 7a in the first embodiment, in terms of the shape of the two thin-film piezoelectric elements 7P and the insulating layer 7Z when viewed along the X-axis. The second embodiment will be described below.

[0095] 2-1. Piezoelectric element 7a in the second embodiment Figure 10 is a cross-sectional view of a part of the liquid discharge head 1a in the second embodiment. The cross-sectional view shown in Figure 10 shows the cross-section along line IV-IV in Figure 2 when the liquid discharge head 1 shown in Figure 2 is replaced with the liquid discharge head 1a. The liquid discharge head 1a differs from the liquid discharge head 1 in that it has a piezoelectric element 7a instead of the piezoelectric element 7.

[0096] Piezoelectric element 7a differs from piezoelectric element 7 in that it has a first thin-film piezoelectric element 7P1a instead of the first thin-film piezoelectric element 7P1, an insulating layer 7Za instead of the insulating layer 7Z, and a second thin-film piezoelectric element 7P2a instead of the second thin-film piezoelectric element 7P2.

[0097] As shown in Figure 10, in the second embodiment, of the two regions in the piezoelectric element 7a where the first individual electrode 7D1 and the second individual electrode 7D2 are not provided in the direction along the Y axis, the region located in the Y1 direction may be described as the inactive region YR1a, and the region located in the Y2 direction may be described as the inactive region YR2a. In the second embodiment, the inactive region YR1a and the inactive region YR2a are examples of the "third region".

[0098] In the non-active regions YR1a and YR2a, the first common electrode 7C1, the first thin-film piezoelectric element 7P1a, the insulating layer 7Za, the second thin-film piezoelectric element 7P2a, and the second common electrode 7C2 are stacked in that order from bottom to top.

[0099] As shown in Figure 10, the second thin-film piezoelectric element 7P2a differs from the second thin-film piezoelectric element 7P2 in that it has a sloping portion 7P22a instead of a sloping portion 7P22. The end of the sloping portion 7P22a in the ZX2 direction is in contact with the insulating layer 7Za. As shown in Figure 10, the second thin-film piezoelectric element 7P2a differs from the second thin-film piezoelectric element 7P2 in that, in Figure 4, it is formed to cover the second individual electrode 7D2 at its ends in the Y1 and Y2 directions, but does not cover the first thin-film piezoelectric element 7P1a, the first individual electrode 7D1, and the insulating layer 7Za. The insulating layer 7Za differs from the insulating layer 7Z in that it is formed to cover the first individual electrode 7D1 at its ends in the Y1 and Y2 directions.

[0100] 2-2. Manufacturing method of piezoelectric element 7a Figure 11 is a flowchart showing the manufacturing method of the piezoelectric element 7a. As shown in Figure 9, the manufacturing method of the piezoelectric element 7a includes the first step S1, the second step S2, the third step S3, the third a step S3a, the fourth a step S4a, the sixth step S6, the seventh a step S7a, the eighth a step S8a, the ninth a step S9a, and the tenth a step S10a. These steps are performed in this order. Note that among the steps shown in Figure 11, steps that are assigned the same reference numerals as the steps shown in Figure 9 are the same steps as those assigned the same reference numerals in Figure 9, and therefore their explanation is omitted.

[0101] In step 3a S3a, the first individual electrode 7D1 is patterned. Patterning is performed using known processing techniques such as etching.

[0102] In step 4a S4a, an insulating layer 7Za is formed so as to cover the first individual electrode 7D1.

[0103] In step 7a S7a, the second individual electrode 7D2 is patterned.

[0104] In step 8a S8a, an orientation control layer 7H is formed to cover the second individual electrode 7D2, and then a second thin-film piezoelectric material 7P2a is formed.

[0105] In step 9a S9a, the first thin-film piezoelectric 7P1a, the insulating layer 7Za, and the second thin-film piezoelectric 7P2a are patterned.

[0106] In step 10a S10a, a second common electrode 7C2 is formed on the second thin-film piezoelectric material 7P2a. The second common electrode 7C2 is formed by known film deposition techniques and known processing techniques.

[0107] After the completion of step 10a S10a, the piezoelectric element 7a is manufactured by firing it at a high temperature.

[0108] Alternatively, after the completion of the third step S3, that is, after the first individual electrode 7D1 has been formed, the first individual electrode 7D1 may be patterned in the third a step S3a so that the ends in the Y1 direction and the Y2 direction of the first individual electrode 7D1 are formed, and after the fourth a step S4a is performed, the first individual electrode 7D1 and the insulating layer 7Z may be patterned. According to this manufacturing method, the insulating layer 7Z can be kept from remaining in the non-active region XR1 and the non-active region XR2.

[0109] 2-3. Summary of the Second Embodiment In the second embodiment described above, in the non-active regions YR1a and YR2a where the first individual electrode 7D1 and the second individual electrode 7D2 are not provided in the direction along the Y axis, the first common electrode 7C1, the first thin-film piezoelectric element 7P1a, the insulating layer 7Za, the second thin-film piezoelectric element 7P2a, and the second common electrode 7C2 are stacked in that order from bottom to top. In the second embodiment, as in the first embodiment, the insulating layer 7Z can suppress the cancellation of the electric field generated by the first individual electrode 7D1 and the first common electrode 7C1 and the electric field generated by the second individual electrode 7D2 and the second common electrode 7C2. In the second embodiment, the piezoelectric element 7a, compared to the piezoelectric element 7 in the first embodiment, shows improved variability and reliability in the second thin-film piezoelectric material 7P2a compared to the second thin-film piezoelectric material 7P2. Fundamentally, forming a thin-film piezoelectric material 7P on an inclined surface is more difficult than forming a thin-film piezoelectric material 7P on a horizontal surface. More specifically, the crystallinity of the thin-film piezoelectric material 7P formed on an inclined surface may differ from that of the thin-film piezoelectric material 7P formed on a horizontal surface. Therefore, the variability and reliability of the thin-film piezoelectric material 7P formed on an inclined surface may be lower than that of the thin-film piezoelectric material 7P formed on a horizontal surface. Furthermore, as can be seen from Figures 4 and 10, the length of the inclined portion 7P22a in the inclined direction is shorter than the length of the inclined portion 7P22 in the inclined direction. Therefore, the second thin-film piezoelectric material 7P2a shows improved variability and reliability compared to the second thin-film piezoelectric material 7P2. Furthermore, as can be seen from a comparison between Figure 4 and Figure 10, in the first embodiment, there is a contact point between the first thin-film piezoelectric element 7P1 and the second thin-film piezoelectric element 7P2 when viewed along the X-axis. When the first thin-film piezoelectric element 7P1 and the second thin-film piezoelectric element 7P2 come into contact, electrical noise may be generated. When electrical noise is generated, the piezoelectric element 7 may be deformed by the voltage of the noise, and ink may be ejected at a timing unintended by the manufacturer of the liquid ejection head 1. Hereinafter, the manufacturer of the liquid ejection head 1 may be referred to as the "head manufacturer". On the other hand, in the second embodiment, when viewed along the X-axis, the first thin-film piezoelectric element 7P1a and the second thin-film piezoelectric element 7P2a are separated by an insulating layer 7Za, and the first thin-film piezoelectric element 7P1a and the second thin-film piezoelectric element 7P2a do not come into contact. Therefore, the piezoelectric element 7a can suppress the possibility of electrical noise generation compared to the piezoelectric element 7. On the other hand, the piezoelectric element 7 in the first embodiment is easier to manufacture compared to the piezoelectric element 7a in the second embodiment. Specifically, as can be understood from the explanation of Figure 9, in the manufacturing method of the piezoelectric element 7, patterning must be performed twice from the first step S1 to the ninth step S9. On the other hand, as can be understood from the explanation of Figure 11, in the manufacturing method of the piezoelectric element 7a, patterning must be performed three times from the first step S1 to the ninth step S9a. In other words, the manufacturing method of the piezoelectric element 7 is easier to manufacture because it requires fewer patterning steps compared to the manufacturing method of the piezoelectric element 7a. Furthermore, in the piezoelectric element 7, since the insulating layer 7Z does not exist in the non-active region YR1 and non-active region YR2, the portion of the first common electrode 7C1 included in the non-active region YR1 and non-active region YR2 is also energized. On the other hand, in the piezoelectric element 7a, the insulating layer 7Za exists in the non-active region YR1a and non-active region YR2a. Therefore, the portions of the first common electrode 7C1 included in the non-active region YR1a and non-active region YR2a are less permeable to current compared to the first embodiment. Consequently, the portions of the first common electrode 7C1 included in the non-active region YR1 and non-active region YR2 can have improved conductivity compared to the second embodiment.

[0110] 3. Variant Each of the forms exemplified above can be modified in various ways. Specific examples of modifications that can be applied to each of the aforementioned forms are given below. Two or more forms arbitrarily selected from the following examples can be combined as appropriate, provided they do not contradict each other.

[0111] 3-1. First variation In the embodiments described above, the second individual electrode 7D2 is described as being thinner than the first individual electrode 7D1, but this is not limited to this. For example, the second individual electrode 7D2 may be thicker than the first individual electrode 7D1. The first modified example will be described below.

[0112] Figure 12 is a cross-sectional view of a portion of the liquid discharge head 1b in the first modified example. The cross-sectional view shown in Figure 12 shows the cross-section along line IV-IV in Figure 2 when the liquid discharge head 1 shown in Figure 2 is replaced with the liquid discharge head 1b. The liquid discharge head 1b differs from the liquid discharge head 1 in that it has a piezoelectric element 7b instead of the piezoelectric element 7.

[0113] The piezoelectric element 7b differs from the piezoelectric element 7 in that it has a first individual electrode 7D1b instead of the first individual electrode 7D1, and a second individual electrode 7D2b instead of the second individual electrode 7D2.

[0114] The thickness TD2b of the second individual electrode 7D2b in the direction along the Z axis is longer than the thickness TD1b of the first individual electrode 7D1b in the direction along the Z axis. Including the thickness TZ of the insulating layer 7Z in the direction along the Z axis, the relationship shown in equation (2) below holds in the first modified example. TZ <TD1b<TD2b (2)

[0115] As described above, according to the first modified example, the second individual electrode 7D2b is thicker than the first individual electrode 7D1b. The piezoelectric element 7a of the present invention can be replaced with an equivalent circuit as shown in Figure 13 when considering the electrical system. That is, a first path ER1 is connected in parallel to the voltage application circuit 910, passing through the first individual electrode 7D1b, the first thin-film piezoelectric element 7P1, and the first common electrode 7C1, and a second path ER2 is connected in parallel to the voltage application circuit 910, passing through the second individual electrode 7D2b, the second thin-film piezoelectric element 7P2, and the second common electrode 7C2. In this case, let I1 be the current flowing through the first path ER1, I2 be the current flowing through the second path ER2, R_7D1 be the electrical resistance of the first individual electrode 7D1b, R_7D2 be the electrical resistance of the second individual electrode 7D2b, and E be the voltage applied from the voltage application circuit 910 to the first path ER1 and the second path ER2 respectively (equal to the differential voltage between the driving voltage Com and the reference voltage VBS). Here, if the first thin-film piezoelectric element 7P1 and the second thin-film piezoelectric element 7P2 have almost the same material and thickness, then their capacitive reactance Xc can be approximated to be substantially the same value. Also, as shown in Figure 12, the first common electrode 7C1 and the second common electrode 7C2 have different shapes, so naturally their electrical resistances are different. However, since they are formed in elongated lengths in the XY plane, their electrical resistances are small, and the difference is negligible. Considering these premises, the only difference between the first path ER1 and the second path ER2 is the electrical resistance R_7D1 of the first individual electrode 7D1b and the electrical resistance R_7D2 of the second individual electrode 7D2b. Here, if the second individual electrode 7D2b is made thicker than the first individual electrode 7D1b, then the electrical resistance R_7D2 becomes smaller than the electrical resistance R_7D1. ​​Therefore, it can be seen that the current I2 flowing through the second path ER2 is larger than the current I1 flowing through the first path ER1. Given the relative magnitudes of these currents and the fact that the capacitive reactances Xc of the first thin-film piezoelectric element 7P1 and the second thin-film piezoelectric element 7P2 are the same, it can be seen that the voltage actually applied to the second thin-film piezoelectric element 7P2 is greater than that applied to the first thin-film piezoelectric element 7P1. As described above, the second thin-film piezoelectric element 7P2, which is further from the neutral axis A1, contributes more to the deformation of the entire piezoelectric element 7 than the first thin-film piezoelectric element 7P1. Therefore, in the piezoelectric element 7a of the present invention, a larger voltage can be applied to the second thin-film piezoelectric element 7P2, which contributes more to the deformation of the entire piezoelectric element 7, thereby optimizing the discharge characteristics. As mentioned above, if physical aspects are prioritized, the piezoelectric element 7 shown in Figure 4 is preferable, while if electrical aspects are prioritized, the piezoelectric element 7b shown in Figure 12 is preferable. This is because it is not possible to say definitively which is better; the suitable configuration will vary depending on whether the rigidity / elasticity (ease of inhibiting deformation of the piezoelectric material) or electrical resistance of each individual electrode is more advantageous.

[0116] 3-2. Second Variation In each of the embodiments described above, the first individual electrode 7D1 and the second individual electrode 7D2 are connected to each other at both ends in the direction along the X-axis of the first individual electrode 7D1 and the second individual electrode 7D2, but they may be connected at only one end. Preferably, the one end that is connected is the connection region XE1. Specifically, in the embodiment where only the connection region XE1 is connected, a voltage drop occurs at the X2-direction end of the first individual electrode 7D1 and the X2-direction end of the second individual electrode 7D2, corresponding to the length of the active region AAR along the X-axis. On the other hand, in the embodiment where only the connection region XE2 is connected, the current supplied to the X1-direction end of the first individual electrode 7D1 passes through the X1-direction end to the X2-direction end of the second individual electrode 7D2, the connection region XE2, and the X2-direction end to the X1-direction end of the first individual electrode 7D1. Therefore, in the configuration where only connection region XE2 is connected, a voltage drop occurs at the X1-direction end of the first individual electrode 7D1, corresponding to twice the length of the active region AAR along the X-axis. Consequently, the configuration where only connection region XE1 is connected can suppress the voltage drop compared to the configuration where only connection region XE2 is connected.

[0117] 3-3. Third Variation In each of the embodiments described above, at least one end of the first individual electrode 7D1 and the second individual electrode 7D2 in the direction along the X axis was connected to each other, but it is not necessary for both ends to be connected. Furthermore, the individual wiring section 73 may have separate wiring for applying a drive voltage Com to the first individual electrode 7D1 and wiring for applying a drive voltage Com to the second individual electrode 7D2. According to the third modification, the drive voltage Com applied to the first individual electrode 7D1 and the drive voltage Com applied to the second individual electrode 7D2 can be made to be different from each other.

[0118] 3-4. Fourth variation In each of the embodiments described above, the insulating layer 7Z is thinner than the first individual electrode 7D1 and the second individual electrode 7D2, but is not limited to this. The insulating layer 7Z may be thicker than at least one of the first individual electrode 7D1 and the second individual electrode 7D2. For example, the insulating layer 7Z may be thicker than the first individual electrode 7D1, and the second individual electrode 7D2 may be thicker than the insulating layer 7Z. That is, the insulating layer 7Z, the first individual electrode 7D1, and the second individual electrode 7D2 may be thicker in proportion to their distance from the neutral axis A1.

[0119] 3-5. Fifth variation In each of the embodiments described above, the orientation control layer 7H is provided between the first thin-film piezoelectric element 7P1 and the first common electrode 7C1, and between the second thin-film piezoelectric element 7P2 and the second common electrode 7C2, but is not limited to this. Figure 14 is a cross-sectional view of a part of the liquid discharge head 1c in the fifth modified example. The cross-sectional view shown in Figure 14 shows the cross-section along line IV-IV in Figure 2 when the liquid discharge head 1 shown in Figure 2 is replaced with the liquid discharge head 1c. The liquid discharge head 1c differs from the liquid discharge head 1 in that it has a piezoelectric element 7c instead of the piezoelectric element 7.

[0120] Piezoelectric element 7c differs from piezoelectric element 7 in that an orientation control layer 7H is provided between the insulating layer 7Z and the second individual electrode 7D2. By providing the orientation control layer 7H at this position, the orientation control layer 7H preferentially orients the crystal of the second thin film piezoelectric body 7P2 to the (100) plane, thereby improving the piezoelectric properties of piezoelectric element 7 compared to the case where the crystal is preferentially oriented to the (110) plane. In particular, when a single crystal of Ti is used as the orientation control layer 7H, orientation control may not be performed effectively unless it is directly laminated on the insulating layer ZrO2. Therefore, when a single crystal of Ti is used for the orientation control layer 7H, this configuration allows for particularly effective control of the orientation of the second thin film piezoelectric body 7P2.

[0121] 3-6. Sixth Variation In the embodiments described above, a serial-type liquid dispensing device in which a transporter 931 equipped with a liquid dispensing head 1 is reciprocated has been illustrated. However, this disclosure can also be applied to a line-type liquid dispensing device in which a plurality of nozzles N are distributed across the entire width of the medium M.

[0122] 3-7. Other variations The liquid dispensing apparatus described above can be used in various devices, including not only equipment dedicated to printing, but also facsimile machines and photocopiers. However, the applications of the liquid dispensing apparatus of this disclosure are not limited to printing. For example, a liquid dispensing apparatus that dispenses a colorant solution can be used as a manufacturing apparatus for forming color filters for liquid crystal display devices. Also, a liquid dispensing apparatus that dispenses a conductive material solution can be used as a manufacturing apparatus for forming wiring and electrodes on a wiring board. [Explanation of Symbols]

[0123] 1,1a,1b…Liquid discharge head, 7,7a,7b…Piezoelectric element, 7C1…First common electrode, 7C2…Second common electrode, 7D1,7D1b…First individual electrode, 7D2,7D2b…Second individual electrode, 7H…Orientation control layer, 7P…Thin film piezoelectric, 7P1,7P1a…First thin film piezoelectric, 7P2…Second thin film piezoelectric, 7P21…Parallel section, 7P22,7P22a…Inclined section, 7P2a…Second thin film piezoelectric, 7Z,7Za…Insulating layer, 11…Nozzle plate, 12 …vibration absorber, 13…flow channel substrate, 14…pressure chamber substrate, 15…diaphragm, 16…wiring board, 16B…bump, 17…housing section, 20…drive circuit, 21…external wiring, 22,23,70…wiring, 73…individual wiring section, 90…liquid container, 91…control unit, 92…transport mechanism, 93…moving mechanism, 100…liquid discharge device, 131…supply channel, 132…communication channel, 133…supply liquid chamber, 151…first layer, 152…second layer, 171…inlet, 731…second 1st wiring section, 732...2nd wiring section, 733...3rd wiring section, 734...4th wiring section, 750...Leadout wiring, 910...Voltage application circuit, 931...Conveyor body, 932...Conveyor belt, A1...Neutral axis, AAR...Active region, AR...Region, C...Pressure chamber, Com...Drive voltage, EK...Intermediate voltage, EM...Minimum voltage, EN...Maximum voltage, Ea...Applied voltage, Ek...Intermediate voltage, Em...Minimum voltage, En...Maximum voltage, ER1...1st path, ER2...2nd path, H1...Contact HO...through hole, L1...first row, L2...second row, M...medium, N...nozzle, R...liquid storage chamber, RE...voltage range, Ra, Rb...space, T1...contraction period, T2...expansion period, TD1, TD1b, TD2, TD2b, TP1, TP2, TZ...thickness, Tu...unit period, VBS...reference voltage, WCom...drive waveform, WEa...waveform, XE1, XE2...connection region, XR1, XR2, YR1, YR1a, YR2, YR2a...inactive region.

Claims

1. A liquid dispensing head, A pressure chamber substrate in which multiple pressure chambers are arranged in the direction of arrangement, The diaphragm and A first common electrode is provided in common to the plurality of pressure chambers, to which a reference voltage that does not change over time is applied, First thin-film piezoelectric material, A first individual electrode is provided for each of the multiple pressure chambers, extending in an extending direction intersecting the aforementioned arrangement direction, and to which a drive voltage that changes over time is applied, Insulating layer and, A second individual electrode is provided for each of the multiple pressure chambers so as to extend in the aforementioned extending direction, and to which a drive voltage that changes over time is applied, The second thin-film piezoelectric material, A second common electrode, which is provided in common to the plurality of pressure chambers and to which the reference voltage is applied, is stacked in this order from bottom to top along the stacking direction that intersects the arrangement direction and the extending direction. A liquid dispensing head characterized in that the first individual electrode and the second individual electrode are separated by the insulating layer in a first region where the first individual electrode and the second individual electrode overlap with the pressure chamber when viewed from the stacking direction.

2. The liquid discharge head according to claim 1, characterized in that the first individual electrode and the second individual electrode are connected to each other in a second region in which the first individual electrode and the second individual electrode do not overlap with the pressure chamber when viewed from the stacking direction.

3. The liquid dispensing head according to claim 2, characterized in that the first individual electrode and the second individual electrode are connected to each other at both one end and the other end in the extending direction of the first individual electrode and the second individual electrode within the second region.

4. The liquid dispensing head according to claim 2, characterized in that in a third region where the first individual electrode and the second individual electrode are not provided in the aforementioned arrangement direction, the first common electrode, the first thin-film piezoelectric material, the insulating layer, the second thin-film piezoelectric material, and the second common electrode are stacked in the order from bottom to top.

5. In the third region where the first individual electrode and the second individual electrode are not provided in the aforementioned arrangement direction, the first common electrode, the second thin-film piezoelectric material, and the second common electrode are stacked in the order from bottom to top, and the first thin-film piezoelectric material and the insulating layer are not stacked, as described in claim 2.

6. The liquid dispensing head according to claim 1, characterized in that the insulating layer is thinner than the first individual electrode and the second individual electrode.

7. The liquid dispensing head according to claim 1, characterized in that the second individual electrode is thinner than the first individual electrode.

8. The liquid dispensing head according to claim 1, characterized in that the second individual electrode is thicker than the first individual electrode.

9. The liquid dispensing head according to claim 1, characterized in that the insulating layer contains zirconium.

10. The liquid dispensing head according to claim 1, characterized in that, in the first region, an orientation control layer containing titanium is provided between the insulating layer and the second individual electrode for controlling the orientation of the second thin-film piezoelectric material.

11. A liquid dispensing head according to any one of claims 1 to 10, A liquid dispensing device characterized by having a control unit that controls the dispensing operation from the liquid dispensing head.

Images