JP2006304588A - Piezoelectric actuator, liquid transfer system, and method of manufacturing piezoelectric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which can materialize both the simplification of electric connection structure for supplying a piezoelectric layer with drive voltage and the improvement of reliability on the connection and further can suppress the generation of surplus capacitance during application of drive voltage, too. <P>SOLUTION: The piezoelectric actuator 3 has a vibrating plate which doubles as a common electrode, covering a plurality of pressure chambers 14, a piezoelectric layer 31 which is arranged continuously, astride the plurality of pressure chambers 14, on the topside of this vibrating plate, a plurality of individual electrodes 32 which are made on the topside of this piezoelectric layer 31, an insulating layer 33 which is made all over the topsides of the plurality of individual electrodes 32, a piezoelectric layer 31, and a plurality of wiring parts 35 which are made on the topside of this insulating layer 33. A through hole 33a is made in a region which faces both the individual electrodes 32 and the wiring parts 35 of the insulating layer 33, and the individual electrodes 32 and the wiring parts 35 are connected with each other by conductive material 36 filled in the through holes 33a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator of a liquid transfer device that transfers a liquid, a liquid transfer device including the piezoelectric actuator, and a method of manufacturing the piezoelectric actuator.

  2. Description of the Related Art As a liquid transfer device that applies pressure to a liquid and transfers it, there is an ink jet head that discharges ink onto a recording medium such as recording paper. Such an ink jet head includes a piezoelectric actuator that is arranged on one surface of a flow path unit including a plurality of pressure chambers each communicating with a nozzle, and selectively changes the volume of the plurality of pressure chambers. There are some (see, for example, Patent Documents 1, 2, and 3).

  A piezoelectric actuator for an inkjet head described in Patent Document 1 (US2004 / 119790A1) includes a piezoelectric layer (piezoelectric sheet) continuously arranged across a plurality of pressure chambers, and a plurality of pressure chambers on the surface of the piezoelectric layer. And a plurality of individual electrodes formed in correspondence with each other, and a common electrode sandwiching the piezoelectric layer between the plurality of individual electrodes. A plurality of land portions are formed on the surfaces of the plurality of individual electrodes, and contact portions of a flexible printed circuit (FPC) are electrically connected to the plurality of land portions. A drive voltage is selectively applied to the plurality of individual electrodes from the drive device (driver IC) via the FPC.

  In addition, in the ink jet head described in Patent Document 2 (US Pat. Nos. 5,754,205 and 5,922,218), the ink jet heads are continuously arranged across a plurality of pressure chambers (pressure chambers). A plurality of drive electrodes (upper drive electrode and lower drive electrode) are formed on the surface of the piezoelectric layer (piezoelectric film), and wirings extend from the plurality of drive electrodes, respectively. The plurality of wires are drawn out in a predetermined direction and connected to the wiring board in a wiring region adjacent to the displacement region where the drive electrode is disposed on the surface of the piezoelectric layer. Here, when a voltage is applied to the drive electrode, in order to prevent an extra capacitance (parasitic capacitance) from being generated between the wiring and the piezoelectric layer sandwiched between the drive electrodes, A low dielectric layer is provided between the piezoelectric layer and the plurality of wirings.

  In addition, in the ink jet head described in Patent Document 3 (US2004 / 0060969 A1), a flexible strip-shaped insulator and one surface of the insulator corresponding to a plurality of head terminals of the ink jet head A plurality of terminal lands arranged in a line, and a plurality of lead wires independently wired to each terminal land on a surface on which the terminal lands of the insulator are arranged, a plurality of inkjet head terminals It is connected to the. Each terminal land of the insulator is formed with a through hole penetrating the insulator, and each terminal land is exposed to the other surface of the insulator through the through hole. After filling the through-hole formed in the insulator with a conductive material such as solder and positioning the terminal land of the flexible wiring board and the head terminal of the inkjet head to face each other, the terminal is formed by the conductive material in the through-hole. Connect the land and the head terminal. At this time, since the conductive material in each through hole and the adjacent terminal land and the conductive wire wired to the terminal land are isolated via an insulator, there is no possibility that they are short-circuited.

US Publication No. US2004 / 119790A1 (Japanese Patent Laid-Open No. 2004-136668) U.S. Pat. Nos. 5,754,205 and 5,922,218 (Japanese Patent Laid-Open No. 9-156099) US Publication No. US2004 / 0060969 A1

  In recent years, attempts have been made to arrange a plurality of pressure chambers in higher density in order to satisfy the demands of both improvement in print image quality and downsizing of the inkjet head. If it is going to arrange | position, it is necessary to arrange | position a several separate electrode also in high density. However, when the driving voltage is supplied from the driving device to the individual electrodes via a wiring member such as an FPC as in the ink jet head described in Patent Document 1, the land of a plurality of individual electrodes is used. Since the wiring pattern of the wiring member connected to the part needs to be formed with high density, the cost of the wiring member increases. In addition, since the contact portion of the wiring member is connected to the land portion in a state where the wiring member such as the FPC is arranged so as to cover the land portions of the plurality of individual electrodes arranged in a plane, an external force is applied to the wiring member. When this occurs, the wiring member is easily peeled off, and the reliability of the electrical connection between the individual electrode and the wiring member is low.

  Similarly, in the ink jet head described in Patent Document 3, when the pressure chambers of the ink jet head are arranged at high density, it is necessary to form the wiring pattern of the flexible wiring board at high density. The cost of Further, since the ink jet head and the flexible wiring board are connected only between each head terminal of the corresponding ink jet head and each land terminal of the flexible wiring board, they are easily peeled off when an external force acts on the flexible wiring board. There is a problem.

  On the other hand, in the ink jet head described in Patent Document 2, a plurality of wirings are drawn out from a plurality of driving electrodes to a wiring region, and the driving device (wiring board) and the driving electrodes are connected via the plurality of wirings. Therefore, the reliability of the electrical connection is high as compared with the above-described configuration using the FPC. However, when the number of pressure chambers is small, it is easy to arrange a plurality of wires extending from a plurality of drive electrodes arranged in the displacement region only in the wiring region, but a large number of pressure chambers have a high density. In the case of being arranged, a part of the wiring must be arranged also in the displacement region where the low dielectric layer is not formed. At this time, extra capacitance is generated in the piezoelectric layer in direct contact with the wiring to which the voltage is applied in the displacement region.

  The object of the present invention is to realize both the simplification of the electrical connection structure for applying a drive voltage to the piezoelectric layer and the improvement of the reliability of the electrical connection. A piezoelectric actuator capable of suppressing the generation of electric capacity, a method of manufacturing the same, and a liquid transfer device using the piezoelectric actuator.

Means for Solving the Problems and Effects of the Invention

  According to the first aspect of the present invention, the plurality of pressure chambers are provided on one surface of a flow path unit in which a liquid flow path including a plurality of pressure chambers arranged along a plane is formed. A piezoelectric actuator of a liquid transfer device that selectively changes, a diaphragm covering the plurality of pressure chambers, a common electrode formed on a surface of the diaphragm opposite to the pressure chambers, and a common electrode A piezoelectric layer continuously disposed across the plurality of pressure chambers on the surface opposite to the pressure chamber; and an insulating layer formed entirely on the surface of the piezoelectric layer opposite to the pressure chamber; A wiring portion formed on the surface of the insulating layer opposite to the pressure chamber and corresponding to each pressure chamber, and a first through-hole is provided in a region of the insulating layer facing the wiring portion. A hole is formed, and the first through hole is filled with a conductive material connected to the wiring portion. The piezoelectric actuator is provided.

  In the piezoelectric actuator according to the first aspect of the present invention, a conductive material filling the inside of the first through hole that penetrates the insulating layer and reaches, for example, the upper surface of the piezoelectric layer, and a driving voltage is supplied to the conductive material. Since the drive device is connected via a plurality of wiring portions formed on the surface of the flat insulating layer, the electrical connection structure for supplying the drive voltage from the drive device is simplified, and further, the FPC It is also possible to omit wiring members such as. Since there is no gap between the insulating layer and the piezoelectric layer, and the insulating layer is formed in close contact with the piezoelectric layer, for example, the mechanical strength of the insulating layer against the force separating the insulating layer and the piezoelectric layer is very high. large. For this reason, the plurality of wiring portions formed on the surface of the insulating layer have higher mechanical strength against external force than a wiring member such as an FPC. Therefore, the mechanical connection and the electrical connection are more reliable than the case where the driving device and the individual electrode are connected via a wiring member such as an FPC, which is arranged on the surface of the plurality of individual electrodes. Increases nature. Furthermore, it is possible to suppress the generation of excess capacitance in the piezoelectric layer sandwiched between the wiring portion and the common electrode. Further, since the piezoelectric layer is protected by the insulating layer, the piezoelectric layer is hardly damaged in the manufacturing stage. The present invention also includes a mode in which the diaphragm has conductivity, and the surface of the diaphragm opposite to the pressure chamber also serves as the surface of the common electrode.

  In the piezoelectric actuator of the present invention, the wiring portion is at least partially opposed to the corresponding pressure chamber, and the first through hole is in a region of the insulating layer facing both the wiring portion and the pressure chamber. The conductive material formed and filled in the first through hole may reach the surface of the piezoelectric layer opposite to the pressure chamber. In this case, for example, even when there is no individual electrode between the surface of the piezoelectric layer opposite to the pressure chamber and the insulating layer, instead of the conductive material filled in the first through hole. When the material reaches the surface of the piezoelectric layer opposite to the pressure chamber, it can serve as an individual electrode. That is, when a driving voltage is applied from the wiring portion to the conductive material filled in the first through-hole extending through the insulating layer and extending to the upper surface of the piezoelectric layer, the conductive material and the common electrode are not connected. An electric field acts on the piezoelectric layer to deform the piezoelectric layer, and pressure is applied to the liquid in the pressure chamber. In this case, in addition to these effects, a step of forming electrodes (individual electrodes) respectively corresponding to the plurality of pressure chambers on the surface of the piezoelectric layer opposite to the pressure chambers becomes unnecessary in the manufacturing stage. Therefore, an effect that the manufacturing process can be simplified is also obtained.

  In the piezoelectric actuator of the present invention, further, an individual electrode corresponding to the pressure chamber is provided between a surface of the piezoelectric layer opposite to the pressure chamber and the insulating layer, and the wiring portion corresponds to the corresponding pressure chamber. The conductive material that is at least partially opposed to the individual electrode, and the first through hole is formed in a region of the insulating layer facing both the wiring portion and the individual electrode, and is filled in the first through hole. Thus, the wiring portion and the individual electrode may be connected. In this case, when a driving voltage is selectively applied to a plurality of individual electrodes, an electric field acts on the piezoelectric layer between the individual electrodes and the common electrode, and the piezoelectric layer is deformed. Along with this, the volume of the pressure chamber corresponding to the individual electrode to which the drive voltage is supplied changes, and pressure is applied to the liquid in the pressure chamber.

  Here, an insulating layer is entirely formed on the surface of the piezoelectric layer and the plurality of individual electrodes (surface opposite to the pressure chamber), and a plurality of wiring portions are formed on the surface of the insulating layer. Each individual electrode and the corresponding wiring portion are connected by a conductive material in a through hole formed in the insulating layer. Accordingly, since the driving device that supplies the driving voltage and the plurality of individual electrodes are connected via the plurality of wiring portions formed on the surface of the flat insulating layer, the electrical connection between the driving device and the individual electrodes is performed. The connection structure is simple, and it is possible to omit wiring members such as FPC. In addition, the reliability of the electrical connection is higher than when the driving device and the individual electrode are connected via a wiring member such as an FPC arranged in a plane on the surface of the plurality of individual electrodes. .

  Furthermore, since an insulating layer is interposed between the wiring portion connected to the individual electrode and the piezoelectric layer, an extra capacitance (parasitic capacitance) is added to the piezoelectric layer portion between the wiring portion and the common electrode. Can be suppressed. Therefore, the driving efficiency of the piezoelectric actuator can be improved, and the cost of the driving device can be reduced. Furthermore, it is possible to prevent the polarization characteristics of the piezoelectric layer from being deteriorated due to this extra capacitance. In addition, since the piezoelectric layer generally has low toughness, the piezoelectric layer is easily damaged when an external force, impact, or the like acts on the piezoelectric layer in the manufacturing stage. However, in the present invention, the piezoelectric layer is covered and protected by the insulating layer, and external forces and impacts acting on the piezoelectric layer are alleviated by the insulating layer. Therefore, the piezoelectric layer is hardly damaged at the manufacturing stage, and the yield in the manufacturing process is improved. The present invention is not limited to a mode in which the diaphragm and the common electrode are formed of separate members, but the diaphragm has conductivity, and the surface of the diaphragm opposite to the pressure chamber is the surface of the common electrode. The aspect which serves as this is also included.

  In the piezoelectric actuator of the present invention, each wiring portion has an end portion facing the corresponding pressure chamber, and the end portion is formed wider than other portions of the wiring portion, and the first through hole May be formed in a region facing the wide end of the insulating layer. As described above, when the end portion of the wiring portion is formed wide and a plurality of first through holes are formed in a region facing the wide end portion, the plurality of first through holes are formed in the plurality of first through holes. With each filled conductive material, a voltage can be reliably applied to a desired region of the piezoelectric layer facing the pressure chamber.

  In the piezoelectric actuator of the present invention, a second through hole may be formed in a region of the insulating layer facing the pressure chamber and not facing the wiring portion. The insulating layer that protects the piezoelectric layer acts to inhibit the deformation of the piezoelectric layer. However, in the present invention, in addition to the first through hole described above, the insulating layer is further formed with a second through hole in a region not facing the wiring portion, and the insulating layer is easily deformed accordingly. Therefore, the deformation of the piezoelectric layer is hardly inhibited by this insulating layer.

  In the piezoelectric actuator of the present invention, the elastic modulus of the conductive material may be smaller than the elastic modulus of the insulating layer. In this case, the conductive material filled in the first through hole is more easily deformed than the insulating layer. That is, since a plurality of through holes are formed in the insulating layer and the inside thereof is filled with a conductive material, the insulating layer is easily deformed, so that the deformation of the piezoelectric layer is hardly inhibited by the insulating layer.

  In the piezoelectric actuator of the present invention, a driving device connected to the plurality of wiring portions may be disposed on the surface of the insulating layer opposite to the pressure chamber. In this case, the individual electrode and conductive material of the present invention that applies a voltage in contact with the piezoelectric layer and the driving device are connected only by a plurality of wiring portions, so that a wiring member such as an FPC becomes unnecessary, and manufacturing is performed. It is advantageous in terms of cost.

  In the piezoelectric actuator according to the aspect of the invention, the driving device and the common electrode may be connected to each other through a conduction portion that extends in the stacking direction across the piezoelectric layer and the insulating layer. Accordingly, in addition to the plurality of wiring portions for applying a voltage to the piezoelectric layer being formed on the surface of the flat insulating layer, the conductive portion for connecting the driving device and the common electrode is also provided on the surface of the insulating layer. The wiring portion and the conductive portion are connected to the driving device on the surface of the insulating layer. For this reason, the electrical connection structure for applying a voltage from the driving device to the piezoelectric layer is simpler than the case of being connected via a wiring member such as an FPC, and the reliability of the connection is also increased.

According to the second aspect of the present invention, a flow path unit in which a liquid flow path including a plurality of pressure chambers arranged along a plane is formed, and provided on one surface of the flow path unit. A piezoelectric actuator that selectively changes the volume of the pressure chamber of
The piezoelectric actuator includes a diaphragm covering the plurality of pressure chambers, a common electrode formed on a surface of the diaphragm opposite to the pressure chamber, and a surface of the common electrode opposite to the pressure chamber. A piezoelectric layer continuously disposed across the plurality of pressure chambers, an insulating layer formed entirely on a surface of the piezoelectric layer opposite to the pressure chamber, and opposite to the pressure chamber of the insulating layer A wiring portion formed on the side surface corresponding to the pressure chamber, and a first through hole is formed in a region of the insulating layer facing the wiring portion. Is provided with a liquid transfer device filled with a conductive material connected to the wiring part.

  According to the liquid transfer device of the present invention, for example, in the case of having a conductive material reaching the surface of the piezoelectric layer, the electrical connection structure for supplying a driving voltage to the conductive material is simplified, and Connection reliability is also increased. Alternatively, for example, when an individual electrode is provided, an electrical connection structure for supplying a drive voltage to the individual electrode is simplified, and the reliability of the electrical connection is increased. In addition, it is possible to suppress generation of excess capacitance in the piezoelectric layer sandwiched between the wiring portion and the common electrode. Furthermore, since the piezoelectric layer is protected by the insulating layer, the piezoelectric layer is hardly damaged in the manufacturing stage. In addition to these, when individual electrodes are not formed, the process of forming electrodes corresponding to a plurality of pressure chambers on the surface opposite to the pressure chambers of the piezoelectric layer is not required, thus simplifying the manufacturing process. The effect that it is possible is also acquired. The present invention includes a mode in which the diaphragm has conductivity, and the surface of the diaphragm opposite to the pressure chamber also serves as the surface of the common electrode.

  According to the third aspect of the present invention, an insulating layer forming step of forming the insulating layer entirely on the surface of the piezoelectric layer opposite to the diaphragm, and facing the pressure chamber of the insulating layer. A through hole forming step of forming a first through hole in the region; a filling step of filling the first through hole with the conductive material so as to reach the piezoelectric layer; and a side of the piezoelectric layer opposite to the diaphragm A method of manufacturing a piezoelectric actuator including a wiring part forming step of forming the wiring part connected to the conductive material on the surface. According to this manufacturing method, the piezoelectric actuator of the present invention having various effects can be obtained.

  In the method for manufacturing a piezoelectric actuator of the present invention, the filling step and the wiring portion forming step may be performed simultaneously. According to this manufacturing method, since the wiring portion can be formed while filling the first through hole with the conductive material, the manufacturing process can be simplified.

  A first embodiment of the present invention will be described. This first embodiment is an example in which the present invention is applied to an inkjet head that ejects ink from nozzles onto recording paper as a liquid transfer device. First, the ink jet printer 100 including the ink jet head 1 will be briefly described. As shown in FIG. 1, an inkjet printer 100 includes a carriage 101 that can move in the left-right direction in FIG. 1, a serial inkjet head 1 that is provided on the carriage 101 and that ejects ink onto a recording paper P, A conveyance roller 102 that conveys the recording paper P forward in FIG. 1 is provided. The ink-jet head 1 moves in the left-right direction (scanning direction) integrally with the carriage 101, and ink is applied to the recording paper P from the emission port of the nozzle 20 (see FIG. 4) formed on the lower ink discharge surface. Inject. Then, the recording paper P recorded by the inkjet head 1 is discharged forward (paper feeding direction) by the transport roller 102.

  Next, the inkjet head 1 will be described in detail with reference to FIGS. As shown in FIGS. 2 to 5, the inkjet head 1 is disposed on the upper surface of the flow path unit 2 in which a plurality of individual ink flow paths 21 including the pressure chambers 14 (see FIG. 4) are formed. The piezoelectric actuator 3 is provided.

  First, the flow path unit 2 will be described. As shown in FIGS. 4 and 6, the flow path unit 2 includes a cavity plate 10, a base plate 11, a manifold plate 12, and a nozzle plate 13, and these four plates 10 to 13 are joined in a stacked state. Yes. Among these, the cavity plate 10, the base plate 11, and the manifold plate 12 are stainless steel plates, and the ink flow paths such as the manifold 17 and the pressure chamber 14 described later can be easily etched in these three plates 10-12. Can be formed. The nozzle plate 13 is made of a polymer synthetic resin material such as polyimide and is bonded to the lower surface of the manifold plate 12. Or this nozzle plate 13 may be formed with metal materials, such as stainless steel, similarly to the three plates 10-12.

  As shown in FIGS. 2 to 4 and 6, a plurality of pressure chambers 14 arranged along a plane are formed in the cavity plate 10, and the plurality of pressure chambers 14 are provided with a diaphragm 30 described later. It opens to the side (upper side of FIGS. 4 and 6). The plurality of pressure chambers 14 are arranged in two rows in the paper feeding direction (up and down direction in FIG. 2). Each pressure chamber 14 is formed in a substantially elliptical shape that is long in the scanning direction (left-right direction in FIG. 2) in plan view.

  As shown in FIGS. 3 and 4, communication holes 15 and 16 are formed at positions where the base plate 11 overlaps both longitudinal ends of the pressure chamber 14 in plan view, respectively. The manifold plate 12 is formed with a manifold 17 extending in the paper feeding direction (vertical direction in FIG. 2). 2 to 4, the manifold 17 overlaps the left half of the pressure chambers 14 arranged on the left side and the right half of the pressure chambers 14 arranged on the right side in plan view. Is arranged. The manifold 17 is connected to an ink supply port 18 formed in a vibration plate 30 described later, and ink is supplied from an ink tank (not shown) through the ink supply port 18. A plurality of communication holes 19 that are continuous with the plurality of communication holes 16 are also formed at positions where the manifold plate 12 overlaps the ends of the pressure chambers 14 opposite to the manifolds 17 in plan view. Further, a plurality of nozzles 20 are respectively formed at positions where the nozzle plate 13 overlaps the plurality of communication holes 19 in a plan view. These nozzles 20 are formed by, for example, excimer laser processing on a polymer synthetic resin substrate such as polyimide.

  As shown in FIG. 4, the manifold 17 communicates with the pressure chamber 14 through the communication hole 15, and the pressure chamber 14 communicates with the nozzle 20 through the communication holes 16 and 19. In this way, the individual ink flow path 21 extending from the manifold 17 to the nozzle 20 through the pressure chamber 14 is formed in the flow path unit 2.

  Next, the piezoelectric actuator 3 will be described. As shown in FIGS. 2 to 6, the piezoelectric actuator 3 is formed on the vibration plate 30 disposed on the upper surface of the flow path unit 2 and on the upper surface of the vibration plate 30 (surface opposite to the pressure chamber 14). A piezoelectric layer 31 and a plurality of individual electrodes 32 respectively formed on the upper surface of the piezoelectric layer 31 so as to correspond to the plurality of pressure chambers 14 are provided.

  The diaphragm 30 is a plate made of a substantially rectangular metal material in plan view, and is made of, for example, an iron-based alloy such as stainless steel, a copper-based alloy, a nickel-based alloy, or a titanium-based alloy. The diaphragm 30 is disposed on the upper surface of the cavity plate 10 so as to cover the plurality of pressure chambers 14, and is joined to the upper surface of the cavity plate 10. The metal diaphragm 30 has conductivity, and also serves as a common electrode for applying an electric field to the piezoelectric layer 31 sandwiched between the diaphragm 30 and the individual electrode 32.

  On the upper surface of the diaphragm 30, a piezoelectric layer 31 mainly composed of lead zirconate titanate (PZT), which is a solid solution and is a ferroelectric substance, is formed of lead titanate and lead zirconate. As shown in FIGS. 2 to 6, the piezoelectric layer 31 is continuously formed across the plurality of pressure chambers 14 on the upper surface of the vibration plate 30.

  A plurality of individual electrodes 32 having an elliptical planar shape that is slightly smaller than the pressure chamber 14 are formed on the upper surface of the piezoelectric layer 31. Each of the plurality of individual electrodes 32 is formed at a position overlapping the central portion of the corresponding pressure chamber 14 in plan view. The individual electrode 32 is made of a conductive material such as gold, copper, silver, palladium, platinum, or titanium.

  As shown in FIGS. 2 to 6, an insulating layer 33 is entirely formed on the upper surfaces of the piezoelectric layer 31 and the plurality of individual electrodes 32. The insulating layer 33 is made of an insulating material such as a ceramic material such as alumina or zirconia, or a synthetic resin material such as polyimide. Note that the dielectric constant of the insulating layer 33 is sufficiently lower than the dielectric constant of the piezoelectric layer 31.

  On the upper surface of the insulating layer 33, a plurality of wiring portions 35 are formed respectively extending from regions facing the end portions on the communication hole 15 side of the plurality of individual electrodes 32 (end portions on the outer side in the width direction of the inkjet head 1). Yes. A through hole 33 a is formed in a region of the insulating layer 33 facing both the end of the individual electrode 32 and the end of the wiring portion 35. Further, as shown in FIGS. 4 and 5, the through hole 33 a is filled with a conductive material 36 and is insulated from the individual electrode 32 located below the insulating layer 33 by the conductive material 36. The wiring part 35 located above the layer 33 is electrically connected.

  As shown in FIG. 2, a driver IC 37 is disposed in a region above the region facing the plurality of pressure chambers 14 (upstream in the paper feeding direction) of the insulating layer 33. The plurality of wiring portions 35 connected to the plurality of individual electrodes 32 via the conductive material 36 extend to the upper side in FIG. 2 on the upper surface of the flat insulating layer 33 and are connected to the driver IC 37. A plurality of terminals 38 (for example, four) connected to the driver IC 37 are also formed on the upper surface of the insulating layer 33, and the driver IC 37 and the driver IC 37 are controlled via the plurality of terminals 38. A control device (not shown) of the inkjet printer 100 is connected. Then, based on a command from the control device, a drive voltage is supplied from the driver IC 37 to the individual electrode 32 via the wiring portion 35 on the upper surface of the insulating layer 33 and the conductive material 36 in the through hole 33a.

  As shown in FIGS. 2 and 7, the insulating layer 33 has a through hole 33b in the vicinity of the driver IC 37, and the piezoelectric layer 31 below the through hole 33b continues to the through hole 33b. A through hole 31a is formed. The two through holes 33b and 31a are filled with a conductive material 39 (conductive portion). The conductive material 39 extends from the upper surface of the insulating layer 33 to the piezoelectric layer 31 and the insulating layer 33. It extends in the laminating direction and reaches the upper surface of the diaphragm 30 as a common electrode. Further, the conductive material 39 is connected to the driver IC 37 via the wiring portion 40 formed on the upper surface of the insulating layer 33. Accordingly, since the diaphragm 30 is connected to the driver IC 37 via the conductive material 39 and the wiring portion 40, the potential of the diaphragm 30 is always held at the ground potential via the driver IC 37.

  Next, the operation of the piezoelectric actuator 3 during the ink discharge operation will be described. When a drive voltage is selectively applied to the plurality of individual electrodes 32 from the driver IC 37, the potential of the individual electrode 32 on the upper side of the piezoelectric layer 31 to which the drive voltage is supplied is below the piezoelectric layer 31 held at the ground potential. The potential of the diaphragm 30 as the common electrode on the side becomes different, and an electric field in the vertical direction is generated in the portion of the piezoelectric layer 31 sandwiched between the individual electrode 32 and the diaphragm 30. At this time, the piezoelectric layer 31 contracts in the horizontal direction orthogonal to the vertical direction that is the polarization direction. As the piezoelectric layer 31 contracts, the diaphragm 30 is deformed so as to protrude toward the pressure chamber 14, so that the volume in the pressure chamber 14 is reduced and pressure is applied to the ink in the pressure chamber 14. Ink droplets are ejected from the nozzle 20 communicating with the chamber 14.

  Here, as described above, the insulating layer 33 is entirely formed on the upper surface of the piezoelectric layer 31 and the plurality of individual electrodes 32, and the wiring portion 35 corresponding to the individual electrode 32 is formed on the upper surface of the insulating layer 33. A wiring portion 40 corresponding to the diaphragm 30 also serving as a common electrode is formed (see FIG. 2). 4 and 7, the individual electrode 32 and the wiring part 35 are connected by the conductive material 36 in the through hole 33a formed in the insulating layer 33, and the diaphragm 30 and the wiring part 40 are also The insulating layer 33 and the piezoelectric layer 31 are connected by the conductive material 39 in the through holes 33b and 31a formed respectively. Further, the driver IC 37 is also disposed on the upper surface of the insulating layer 33 and is connected to the wiring portions 35 and 40. Accordingly, the driver IC 37, the plurality of individual electrodes 32, and the diaphragm 30 as a common electrode are formed on the upper surface of the flat insulating layer 33 without using a wiring member such as an FPC in which a fine wiring pattern is formed. Further, it is possible to connect via a plurality of wiring portions 35 and 40. Therefore, the electrical connection structure of the plurality of wiring portions 35 and 40 can be simplified, which is advantageous in terms of manufacturing cost. Further, when the driver IC 37, the individual electrode 32, and the diaphragm 30 are connected via a wiring member such as an FPC, which is disposed in a plane on the surface of the plurality of individual electrodes 32 (for example, the above-described patent document). 1), the reliability of electrical connection is increased.

  In addition, an insulating layer 33 having a dielectric constant lower than that of the piezoelectric layer 31 is interposed between the plurality of wiring portions 35 and the piezoelectric layer 31. Due to this insulating layer, it is possible to suppress the generation of excess capacitance in the portion of the piezoelectric layer 31 between the wiring portion 35 to which the driving voltage is applied and the diaphragm 30. Therefore, since loss due to discharge is suppressed, the driving efficiency of the piezoelectric actuator 3 is improved, and the cost of the driver IC 37 can be reduced. Furthermore, it is possible to prevent the polarization characteristics of the piezoelectric layer 31 from being deteriorated as much as possible due to this extra capacitance.

  In addition, since the piezoelectric layer 31 made of a piezoelectric ceramic material such as PZT is generally low in toughness, for example, when an external force or impact is applied to the piezoelectric layer 31 in the manufacturing stage of the inkjet head 1, Damages such as cracks and cracks are likely to occur. However, in the piezoelectric actuator 3 according to the first embodiment, since the piezoelectric layer 31 is covered and protected by the insulating layer 33, external force and impact acting on the piezoelectric layer 31 are alleviated by the insulating layer 33, and the piezoelectric layer 31 is piezoelectric. The layer 31 is less likely to be damaged, and the yield in the manufacturing stage is improved.

  Next, a manufacturing method of the piezoelectric actuator 3 will be described with reference to FIG. First, as shown in FIG. 8A, the piezoelectric layer 31 is formed on one surface of the diaphragm 30. Here, the piezoelectric layer 31 can be formed using, for example, an aerosol deposition method (AD method) in which very small particles of a piezoelectric material are sprayed onto a substrate to collide at high speed and are deposited on the substrate. Alternatively, it can be formed by a sputtering method, a chemical vapor deposition method (CVD method), a sol-gel method, a solution coating method, a hydrothermal synthesis method, or the like. It is also possible to form the piezoelectric layer 31 by attaching a piezoelectric sheet obtained by firing a PZT green sheet to the diaphragm 30.

  Next, as shown in FIG. 8B, a plurality of individual electrodes 32 are formed on the upper surface of the piezoelectric layer 31 by screen printing or the like. Further, as shown in FIG. 8C, an insulating layer 33 is formed on the entire top surface of the piezoelectric layer 31 and the plurality of individual electrodes 32. Here, for example, when the insulating layer 33 is formed of a ceramic material such as alumina or zirconia, a method such as an AD method, a sputtering method, a CVD method, a sol-gel method, a solution coating method, or a hydrothermal synthesis method is used. be able to. When the insulating layer 33 is formed of a synthetic resin material such as polyimide, a method such as screen printing, spin coating, or blade coating can be used.

  Next, as shown in FIG. 8D, a plurality of through holes 33a for the individual electrodes 32 are formed in the insulating layer 33 by laser processing or the like. Although not shown in FIG. 8, at the same time, a through hole 33b for the diaphragm 30 (common electrode) and a through hole 31a (see FIG. 7) of the piezoelectric layer 31 connected to the through hole 33b are simultaneously formed. In this case, the laser output is increased or the laser irradiation time is made longer than when the through-hole 33a is formed. Further, as shown in FIG. 8E, the through hole 33a is filled with the conductive material 36 and the through holes 33b and 31a are filled with the conductive material 39 by a method such as a droplet discharge method or screen printing. (See FIG. 7). Further, as shown in FIG. 8D, a wiring portion 35 for connecting the individual electrodes 32 and a wiring portion 40 for connecting the diaphragm 30 (see FIG. 7) are formed on the upper surface of the insulating layer 33 by screen printing or the like. To do. At this time, a plurality of wiring portions 35 corresponding to the plurality of individual electrodes 32 and a wiring portion 40 corresponding to the diaphragm 30 (common electrode) can be formed on the upper surface of the flat insulating layer 33 at a time. The wiring portions 35 and 40 can be easily formed.

  As shown in FIG. 8D, after the through holes 33a and 33b are formed in the insulating layer 33, the through holes 33a and 33b are filled with the conductive materials 36 and 39 by a method such as screen printing. The wiring portions 35 and 40 may be formed on the upper surface of the insulating layer 33 with the same material as the conductive materials 36 and 39. In this case, since the filling of the conductive materials 36 and 39 and the formation of the wiring portions 35 and 40 can be performed at the same time, the manufacturing process can be simplified, which is advantageous in terms of manufacturing cost.

  Next, modified embodiments in which various modifications are made to the first embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

<First modification>
In the first embodiment, the wiring portion 40 connected to the driver IC 37 on the upper surface of the insulating layer 33 and the diaphragm 30 as a common electrode are connected by the conductive material 39 in the through holes 33b and 31a. (See FIG. 7) As shown in FIG. 9, wiring portions 51 (conducting portions) extending in the stacking direction across the insulating layer 33 and the piezoelectric layer 31 are formed on the side surfaces of the insulating layer 33 and the piezoelectric layer 31. The wiring part 50 formed on the upper surface of the insulating layer 33 and the diaphragm 30 may be connected by the wiring part 51. In addition, this wiring part 51 can be formed by apply | coating a conductive paste to the side surface of the insulating layer 33 and the piezoelectric layer 31, for example.

<Second modification>
The upper surface of the diaphragm 30 does not necessarily have to serve as a common electrode, and the common electrode 34 may be provided separately from the diaphragm 30 as shown in FIG. However, when the diaphragm 30 is a metal plate, an insulating material layer is formed on the upper surface of the diaphragm 30 on which the common electrode 34 is formed, so that the upper surface of the diaphragm 30 has an insulating property. Need to be. When the diaphragm 30 is made of a silicon material, the upper surface of the diaphragm 30 may be oxidized to have insulation. When the diaphragm 30 is made of an insulating material such as a ceramic material or a synthetic resin material, the common electrode 34 is directly formed on the upper surface of the diaphragm 30.

  Next, a second embodiment of the present invention will be described. However, components having the same configuration as in the first embodiment are denoted by the same reference numerals and description thereof is omitted as appropriate. As shown in FIGS. 11 and 12, the inkjet head 61 of the second embodiment includes a flow path unit 2 in which a plurality of pressure chambers 14 are formed, and a piezoelectric actuator 63 disposed on one surface of the flow path unit 2. And. The flow path unit 2 is the same as that in the first embodiment, and a description thereof will be omitted.

  The piezoelectric actuator 63 is different from the piezoelectric actuator 3 of the first embodiment in that the individual electrode 32 (see FIG. 4) facing the pressure chamber 14 is omitted. As shown in FIGS. 11 to 13, the piezoelectric actuator 63 covers the plurality of pressure chambers 14 and spans the plurality of pressure chambers 14 on the upper surface of the vibration plate 30 and the metal diaphragm 30 also serving as a common electrode. And the piezoelectric layer 31 arranged continuously. The individual electrode 32 (see FIG. 4) in the first embodiment is not formed on the upper surface of the piezoelectric layer 31. On the other hand, an insulating layer 73 made of an insulating material such as a ceramic material or a synthetic resin material is formed on the upper surface of the piezoelectric layer 31 as in the first embodiment. Further, a plurality of wiring portions 75 are formed on the upper surface of the insulating layer 73 so as to face the plurality of pressure chambers 14 at the end portions 75a. Here, as shown in FIG. 11, the end portion 75 a of each wiring portion 75 has a substantially oval planar shape that is slightly smaller than the pressure chamber 14, and is formed wider than other portions of the wiring portion 75. Has been.

  Further, a plurality of through holes 73a (first through holes) are formed in a region of the insulating layer 73 facing the wide end 75a of each wiring portion 75 (a region facing both the pressure chamber 14 and the wiring portion 75). Is formed. Further, each of the plurality of through holes 73 a is filled with a conductive material 76 connected to the wiring portion 75 so as to reach the upper surface of the piezoelectric layer 31. That is, the conductive material 76 filled in the plurality of through holes 73 a is in contact with the upper surface of the piezoelectric layer 31, and these conductive materials 76 apply a voltage to the piezoelectric layer 31. It plays the role of the electrode 32. That is, when a driving voltage is applied to the plurality of conductive materials 76 via the wiring portion 75 from the driver IC 37 (see FIG. 2) having the same configuration as that of the first embodiment, the conductive material 76 and the common electrode An electric field is generated in the portion of the piezoelectric layer 31 between the diaphragm 30 and the piezoelectric layer 31, and the piezoelectric layer 31 is deformed.

  According to the piezoelectric actuator 63 of the second embodiment, similarly to the piezoelectric actuator 3 of the first embodiment, the conductive material 76 that contacts the piezoelectric layer 31 in the plurality of through holes 73a, and these conductive materials 76. Since a driver IC 37 that supplies a driving voltage to the driver IC 37 can be connected via a plurality of wiring portions 75 formed on the surface of the flat insulating layer 73, a wiring member such as an FPC can be omitted. Also, the reliability of electrical connection is increased. In addition, it is possible to suppress the generation of excessive capacitance in the piezoelectric layer 31 sandwiched between the wiring portion 75 and the diaphragm 30 as the common electrode. Furthermore, since the piezoelectric layer 31 is protected by the insulating layer 73, the piezoelectric layer 31 is not easily damaged in the manufacturing stage.

  In addition, the end 75a of the wiring portion 75 on the upper surface of the insulating layer 73 facing the pressure chamber 14 is formed wide, and a plurality of through holes 73a are formed in the region facing the wide end 75a. Therefore, a voltage can be reliably applied to a desired region of the piezoelectric layer 31 facing the pressure chamber 14 by the conductive material 76 filled in each of the plurality of through holes 73a.

  The insulating layer 73 that protects the piezoelectric layer 31 acts to inhibit the deformation when the piezoelectric layer 31 is deformed. Therefore, by providing the insulating layer 73 on the upper surface of the piezoelectric layer 31, the driving efficiency of the piezoelectric actuator 63 is improved. Is somewhat lower. However, in the second embodiment, a plurality of through holes 73a are formed in the insulating layer 73, and the elastic modulus (for example, epoxy-based conductivity) of the conductive material 76 filled in the plurality of through holes 73a is further provided. Adhesive: 4 GPa) is smaller than the elastic modulus of the insulating layer 73 (for example, alumina: 300 GPa, polyimide: 6 GPa). That is, the conductive material 76 filled in the through hole 73 a is more easily deformed than the insulating layer 73. Therefore, a plurality of through holes 73a are formed in the insulating layer 73, and the inside thereof is filled with the conductive material 76, so that the insulating layer 73 is more easily deformed than when the through hole 73a and the conductive material 76 are absent. Therefore, the deformation of the piezoelectric layer 31 is not easily inhibited by the insulating layer 73.

  Next, a manufacturing method of the piezoelectric actuator 63 will be described with reference to FIG. First, as shown in FIG. 14A, the piezoelectric layer 31 is formed on one surface of the diaphragm 30. Here, the piezoelectric layer 31 can be formed by an AD method, a sputtering method, a chemical vapor deposition method (CVD method), a sol-gel method, a solution coating method, a hydrothermal synthesis method, or the like. Alternatively, the piezoelectric layer 31 can be formed by attaching a piezoelectric sheet obtained by firing a PZT green sheet to the diaphragm 30.

  Next, as shown in FIG. 14B, an insulating layer 73 is entirely formed on the upper surface of the piezoelectric layer 31 (insulating layer forming step). Here, for example, when the insulating layer 73 is formed of a ceramic material such as alumina or zirconia, a method such as an AD method, a sputtering method, a CVD method, a sol-gel method, a solution coating method, or a hydrothermal synthesis method is used. be able to. In the case where the insulating layer 73 is formed of a synthetic resin material such as polyimide, screen printing, spin coating, or blade coating can be used.

  And as shown in FIG.14 (c), the some through-hole 73a is formed in the insulating layer 73 by laser processing etc. (through-hole formation process). Then, as shown in FIG. 14D, the conductive material 76 is filled into the plurality of through holes 73a so as to reach the upper surface of the piezoelectric layer 31 by a method such as a droplet discharge method or screen printing (filling step). ). Further, as shown in FIG. 14E, a wiring portion 75 having a wide end portion 75a is formed on the upper surface of the insulating layer 73 by screen printing or the like (wiring portion forming step).

  In the second embodiment, similarly to the first embodiment, in the wiring portion forming step, a plurality of wiring portions 75 respectively corresponding to the plurality of pressure chambers 14 are formed on the upper surface of the flat insulating layer 73 at a time. Therefore, the wiring portions 75 can be easily formed. In addition to this, the step of forming individual electrodes corresponding to the plurality of pressure chambers 14 on the surface of the piezoelectric layer 31 opposite to the pressure chambers 14 is not necessary, and thus the manufacturing process can be simplified. can get.

  In the second embodiment as well, after the through hole 73a is formed in the insulating layer 73 as shown in FIG. 14C, the conductive material 76 is filled in the through hole 73a by a method such as screen printing. The wiring portion 75 may be formed on the upper surface of the insulating layer 73 with the same material as the conductive material 76. In this case, since the filling of the conductive material 76 and the formation of the wiring portion 75 can be performed simultaneously, the manufacturing process can be simplified, which is advantageous in terms of manufacturing cost.

  Next, modified embodiments in which various modifications are made to the second embodiment will be described. However, components having the same configuration as in the second embodiment are denoted by the same reference numerals and description thereof is omitted as appropriate.

<First modification>
In the second embodiment, a plurality of through holes 73a (first through holes) are formed only in a region of the insulating layer 73 facing the wide end 75a of the wiring part 75. As shown in FIG. 5, a plurality of through holes 73 b (second through holes) may be formed in a region of the insulating layer 73 </ b> A that faces the pressure chamber 14 but does not face the wiring portion 75. As described above, since the plurality of through holes 73b are formed also in the region not facing the wiring portion 75, the insulating layer 73A is further easily deformed, and the deformation of the piezoelectric layer 31 is not easily inhibited by the insulating layer 73A. . Of course, unlike the through hole 73 a formed in the region facing the wiring part 75, the conductive material 76 is not filled in the plurality of through holes 73 b formed in the region not facing the wiring part 75.

<Second modification>
As shown in FIGS. 17 and 18, a large-diameter through hole 73c having an opening area substantially equal to the area of the end portion 75a is formed in a region of the insulating layer 73B facing the wide end portion 75a of the wiring portion 75. One may be formed, and this large-diameter through hole 73c may be filled with a conductive material 76B. In this case, since the contact area between the conductive material 76B and the piezoelectric layer 31 is larger than that in the second embodiment, a voltage can be more reliably applied to the piezoelectric layer 31.

<Third modification>
In addition, the second embodiment is also different from the first embodiment described above (a configuration in which the conductive portions of the driver IC 37 and the diaphragm 30 are formed on the side surfaces of the insulating layer and the piezoelectric layer (see FIG. 9) The common electrode 34 can be modified in the same manner as the embodiment in which the common electrode 34 is provided separately from the diaphragm 30 (see FIG. 10).

  As mentioned above, although the form which applied this invention to the inkjet head was described taking the 1st Embodiment and 2nd Embodiment as an example, the form which can apply this invention is these 1st Embodiment and 2nd Embodiment. It is not limited. For example, the present invention can be applied to various liquid transfer devices that transfer liquids other than ink.

FIG. 1 is a schematic configuration diagram of an ink jet printer according to a first embodiment of the present invention. FIG. 2 is a plan view of the inkjet head. FIG. 3 is a partially enlarged view of FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is an enlarged view of a portion surrounded by a one-dot chain line in FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a sectional view taken along line VII-VII in FIG. 8A and 8B are diagrams showing the manufacturing process of the piezoelectric actuator of the first embodiment. FIG. 8A is a piezoelectric layer forming process, FIG. 8B is an individual electrode forming process, and FIG. 8C is an insulating layer forming process. 8D shows a through hole forming step, FIG. 8E shows a conductive material filling step, and FIG. 8F shows a wiring portion forming step. FIG. 9 is a cross-sectional view corresponding to FIG. 7 according to a modification of the first embodiment. FIG. 10 is a cross-sectional view corresponding to FIG. 4 according to another modification of the first embodiment. FIG. 11 is a partially enlarged plan view of the ink jet head according to the second embodiment. 12 is a cross-sectional view taken along line XII-XII in FIG. FIG. 13 is an enlarged view of a portion surrounded by a one-dot chain line in FIG. 14A and 14B are diagrams showing a manufacturing process of the piezoelectric actuator of the second embodiment. FIG. 14A is a piezoelectric layer forming process, FIG. 14B is an insulating layer forming process, and FIG. 14C is a through hole forming process. FIG. 14D shows a process of filling a conductive material, and FIG. 14E shows a wiring part forming process. FIG. 15 is a partially enlarged plan view corresponding to FIG. 11 according to a modification of the second embodiment. 16 is a cross-sectional view taken along line XVI-XVI in FIG. FIG. 17 is a partially enlarged plan view corresponding to FIG. 11 according to another modification of the second embodiment. 18 is a cross-sectional view taken along line XVIII-XVIII in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet head 2 Flow path unit 3 Piezoelectric actuator 14 Pressure chamber 30 Diaphragm 31 Piezoelectric layer 32 Individual electrode 33 Insulating layer 33a Through-hole 34 Common electrode 35 Wiring part 36 Conductive material 39 Conductive material (conductive part)
51 Wiring part (conductive part)
61 Inkjet head 63 Piezoelectric actuators 73, 73A, 73B Insulating layer 73a Through hole (first through hole)
73b Through hole (second through hole)
73c Through-hole 75 Wiring part 75a End part 76, 76B Conductive material

Claims (18)

A piezoelectric actuator of a liquid transfer device, which is provided on one surface of a flow path unit in which a liquid flow path including a plurality of pressure chambers arranged along a plane is formed, and selectively changes the volume of the plurality of pressure chambers. Because
A diaphragm covering the plurality of pressure chambers;
A common electrode formed on the surface of the diaphragm opposite to the pressure chamber;
A piezoelectric layer continuously disposed across the plurality of pressure chambers on the surface of the common electrode opposite to the pressure chambers;
An insulating layer formed entirely on the surface of the piezoelectric layer opposite to the pressure chamber;
A wiring portion formed on the surface of the insulating layer opposite to the pressure chamber, corresponding to the pressure chamber;
A first through hole is formed in a region of the insulating layer facing the wiring portion,
The piezoelectric actuator, wherein the first through hole is filled with a conductive material connected to the wiring portion.   The wiring portion is at least partially opposed to the corresponding pressure chamber, and the first through hole is formed in a region of the insulating layer facing both the wiring portion and the pressure chamber. The piezoelectric actuator according to claim 1, wherein the conductive material filled in reaches a surface of the piezoelectric layer opposite to the pressure chamber.   Further, an individual electrode corresponding to the pressure chamber is provided between the surface of the piezoelectric layer opposite to the pressure chamber and the insulating layer, and the wiring portion includes at least a part of the corresponding individual electrode. The first through holes are opposed to each other, and the first through holes are formed in regions of the insulating layer facing both the wiring portions and the individual electrodes, and the conductive portions filled in the first through holes are used to connect the wiring portions and the individual through holes. The piezoelectric actuator according to claim 1, wherein the piezoelectric actuator is connected to the electrode.   The wiring part has an end part facing the corresponding pressure chamber, the end part is formed wider than the other part of the wiring part, and the first through hole is a wide part of the insulating layer. The piezoelectric actuator according to claim 2, wherein a plurality of the piezoelectric actuators are formed in a region facing the end of the piezoelectric actuator.   3. The piezoelectric actuator according to claim 2, wherein a second through hole is formed in a region of the insulating layer facing the pressure chamber and not facing the wiring portion.   The piezoelectric actuator according to claim 2, wherein an elastic modulus of the conductive material is smaller than an elastic modulus of the insulating layer.   The piezoelectric actuator according to claim 1, wherein a driving device connected to the plurality of wiring portions is disposed on a surface of the insulating layer opposite to the pressure chamber.   The piezoelectric actuator according to claim 7, wherein the driving device and the common electrode are connected to each other through a conduction portion extending in the stacking direction across the piezoelectric layer and the insulating layer. A flow path unit in which a liquid flow path including a plurality of pressure chambers arranged along a plane is formed, and provided on one surface of the flow path unit to selectively change the volumes of the plurality of pressure chambers. A piezoelectric actuator,
The piezoelectric actuator is
A diaphragm covering the plurality of pressure chambers;
A common electrode formed on the surface of the diaphragm opposite to the pressure chamber;
A piezoelectric layer continuously disposed across the plurality of pressure chambers on the surface of the common electrode opposite to the pressure chambers;
An insulating layer formed entirely on the surface of the piezoelectric layer opposite to the pressure chamber;
On the surface of the insulating layer opposite to the pressure chamber, a wiring portion formed corresponding to the pressure chamber,
A first through hole is formed in a region of the insulating layer facing the wiring portion,
The liquid transfer apparatus, wherein the first through hole is filled with a conductive material connected to the wiring portion.   The wiring portion is at least partially opposed to the corresponding pressure chamber, and the first through hole is formed in a region of the insulating layer facing both the wiring portion and the pressure chamber. The liquid transfer device according to claim 9, wherein the conductive material filled in reaches a surface of the piezoelectric layer opposite to the pressure chamber.   The piezoelectric actuator further includes an individual electrode corresponding to the pressure chamber between a surface of the piezoelectric layer opposite to the pressure chamber and the insulating layer, and the wiring portion corresponds to the corresponding individual electrode. And the first through hole is formed in a region of the insulating layer facing both the wiring portion and the individual electrode, and the conductive material filled in the first through hole is used to form the first through hole. The liquid transfer device according to claim 9, wherein a wiring portion and the individual electrode are connected.   The wiring part has an end part facing the corresponding pressure chamber, the end part is formed wider than the other part of the wiring part, and the first through hole is a wide part of the insulating layer. The liquid transfer device according to claim 10, wherein a plurality of liquid transfer devices are formed in a region facing the end of the liquid crystal.   The liquid transfer device according to claim 10, wherein a second through hole is formed in a region of the insulating layer facing the pressure chamber and not facing the wiring portion.   The liquid transfer device according to claim 10, wherein an elastic modulus of the conductive material is smaller than an elastic modulus of the insulating layer.   The liquid transfer device according to claim 10, wherein a driving device connected to the plurality of wiring portions is disposed on a surface of the insulating layer opposite to the pressure chamber.   The liquid transfer device according to claim 15, wherein the driving device and the common electrode are connected to each other through a conduction portion extending in the stacking direction across the piezoelectric layer and the insulating layer. A method of manufacturing the piezoelectric actuator according to claim 2,
An insulating layer forming step of forming the insulating layer entirely on the surface of the piezoelectric layer opposite to the diaphragm;
A through hole forming step of forming a first through hole in a region of the insulating layer facing the pressure chamber;
A filling step of filling the first through hole with the conductive material so as to reach the piezoelectric layer;
A wiring portion forming step of forming the wiring portion connected to the conductive material on a surface of the piezoelectric layer opposite to the diaphragm;
A method of manufacturing a piezoelectric actuator comprising:   The method for manufacturing a piezoelectric actuator according to claim 17, wherein the filling step and the wiring portion forming step are performed simultaneously.

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