JP2006093476A - Cell-driven piezoelectric actuator and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which requires no special processing, etc. and can be installed in an application apparatus without damaging the elastic displacement of a piezoelectric body. <P>SOLUTION: The cell-driven piezoelectric actuator 60 is a sintered and integrated substrate 2, driving portion 63, and periphery 64a. The driving portion 63 consists of a piezoelectric element 34 wherein a plurality of layered piezoelectric bodies 14 and layered driving electrodes 18 and 19 are alternately stacked, and contains a cell 3 which varies in volume by elastic displacement of the piezoelectric element 34. The driving portion 63 is lower than the peripheral portion 64a. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cell driving type piezoelectric actuator provided with a cell whose volume is changed by displacement of a piezoelectric element. More specifically, the present invention relates to a cell driving type piezoelectric actuator that can be used as an ink jet head and can discharge ink filled in an ink chamber composed of cells by changing the volume of the ink chamber, and a manufacturing method thereof.

  Piezoelectric actuators are used as inkjet heads in printers, facsimiles, copiers, and other printing equipment. Printing equipment that uses high-performance piezoelectric actuators as inkjet heads produces clear images such as silver halide photographs on paper. Since it can be reproduced, it has been heavily used. An ink jet head using a piezoelectric actuator is mainly composed of an ink chamber (ink channel) communicating with an ink supply path and a piezoelectric element that causes a volume change in the ink chamber, and applies a drive voltage to the piezoelectric element. Then, a volume change is generated in the ink chamber, and ink is ejected from a nozzle provided in the ink chamber, thereby performing printing and printing.

  In recent years, in the field of printing equipment including such an ink jet head, there has been a demand for higher speed and higher functionality, and in response to this, there has been a demand for higher nozzle density and higher density of the ink jet head. The piezoelectric actuators for heads are becoming smaller and narrower in pitch. Furthermore, in order to meet the needs of diversification of ink types to be used and ejection amount control by drive voltage control, the displacement amount of the piezoelectric actuator is always required to have high characteristics even if it is small and high density. .

For example, Patent Document 1 discloses an ink jet (recording) head using a piezoelectric actuator. In the inkjet head proposed in Patent Document 1, ink channels (corresponding to cells) and dummy channels are alternately formed via the side walls of the piezoelectric body, and the electrodes formed in each ink channel are used as common electrodes, and each dummy channel is formed. The electrodes formed in the individual electrodes are configured so that the ink is not brought into contact with the passivation film formed on the individual electrodes, and by applying an electric field using the electrodes formed in each channel, The side wall (piezoelectric material) forming the ink channel is expanded or contracted (by displacement based on the piezoelectric lateral effect), and the volume in the ink channel is changed to eject ink droplets.
Japanese Patent No. 2873287

  In response to these demands, the use of a piezoelectric actuator utilizing the longitudinal effect of electric field induced strain, which can obtain a higher displacement and a larger driving force, has caused problems caused by this. One is that the direction of displacement by applying an electric field is a direction that extends compared to the state in which no electric field is applied, and the other is crosstalk that occurs due to a large driving force (driving of a certain element). The phenomenon in which the vibration caused by the above phenomenon extends to other elements is further expanded and affects the entire substrate of the piezoelectric actuator.

  When the above-described ink jet head is attached to a printing device as a basic part, the displacement direction is an extending direction, which causes a problem that the attachment is complicated. That is, as shown in FIG. 4 of Patent Document 1, since the side wall forming the ink channel extends, the top plate side (side wall of the inkjet head) is provided so as to provide a constant space in the extension direction so as not to prevent the extension. There is a problem to be solved that the mounting surface on the extending direction side) needs to be counterbored, drilled, and the like, and the labor of the printing reduces the productivity of the printing apparatus. On the other hand, as means for preventing crosstalk, a means for securing a wider area for fixing the actuator and fixing it more firmly is required.

  The present invention has been made in view of the above-described problems of the prior art, and the object of the present invention is a piezoelectric actuator applicable as an ink-jet head, which does not require any special processing and the like. Another object of the present invention is to provide a piezoelectric actuator that can be attached to an applied device so as not to inhibit expansion and contraction displacement of the piezoelectric body.

  As a result of research, in order to change the volume of the cell (ink channel) in the drive unit by providing a drive unit provided with the cell and an outer peripheral part that can be used for mounting, the disclosure is disclosed in Patent Document 1. Instead of expanding and contracting the piezoelectric body by the displacement based on the lateral effect of the electric field induced strain as in the case of the inkjet head, the cell is formed by the piezoelectric element in which the piezoelectric body and the (drive) electrode are alternately laminated, thereby causing the electric field induction. The piezoelectric element (piezoelectric body) is expanded and contracted using expansion and contraction displacement based on the longitudinal effect of strain, and in addition, the pattern shape of the stacked driving electrodes and the wiring electrode pattern for connecting the driving electrodes to an external power source By devising the relationship between the shape and the size (width), the cell driving type piezoelectric actuator in which the piezoelectric element forming the cell, that is, the driving part is formed lower than the outer peripheral part. By providing over data, the object is found to be achieved, the present invention has been completed.

  That is, first, according to the present invention, a drive unit and an outer peripheral part located on the outer periphery thereof are provided on a substrate, and the drive unit is formed by connecting two aligned side walls with a ceiling wall. Consists of a plurality of cells, and at least two side walls are composed of piezoelectric elements in which a plurality of layered piezoelectric bodies and layered drive electrodes are alternately stacked, and expansion and contraction based on the longitudinal effect of the electric field induced strain of the piezoelectric elements A cell drive type piezoelectric device in which the volume of the cell can be changed by the displacement, the height of the drive part is lower than the outer peripheral part at least in the longitudinal direction of the cell, and the substrate, the drive part and the outer peripheral part are integrated by firing. An actuator is provided.

  In the cell drive type piezoelectric actuator according to the present invention, the drive part is lower than the outer peripheral part at least in the longitudinal direction of the cell. This is a comparison based on the height with the substrate as the reference plane. It means that it is low as a cell drive type piezoelectric actuator that has been processed and is not processed.For example, if the drive part is lower than the outer peripheral part as a result of adding a member etc. to the outer peripheral part, Absent.

  In the cell drive type piezoelectric actuator according to the present invention, the difference in height between the drive unit and the outer peripheral part is larger than the expansion / contraction displacement of the piezoelectric element, and the thickness per layer of the layered piezoelectric body constituting the piezoelectric element. It is preferable that it is 1/2 or less.

  This is because the difference in height between the drive part and the outer peripheral part is preferably at least larger than the displacement of the piezoelectric element due to its effect (to be described later). Since the difference in thickness is preferably small, it is a condition of a preferable aspect in the cell driving type piezoelectric actuator according to the present invention obtained from these requirements.

  Further, in the outer peripheral portion, a wiring electrode connected to the driving electrode for applying a driving voltage to the piezoelectric element and a band-like dummy electrode having a width of 200 μm or less are sandwiched between a plurality of layered piezoelectric bodies to drive. It is preferable that it is formed so as to surround the outer periphery of the part.

  Further, in the piezoelectric element constituting the side wall in the driving unit, it is preferable that all of the plurality of layered driving electrodes are exposed on the side surface of the side wall.

  In this case, the exposed end face of the layered drive electrode is preferably a surface fired after fracture by punching.

  In the cell driving type piezoelectric actuator according to the present invention, it is preferable that an insulating film is formed on the inner wall of the cell in the driving unit.

  Next, according to the present invention, the driving unit and the outer peripheral part located on the outer periphery of the driving unit are provided on the substrate, and the driving unit is a cell formed by connecting two aligned side walls with a ceiling wall. And at least two side walls are composed of piezoelectric elements in which a plurality of layered piezoelectric bodies and layered drive electrodes are alternately stacked, and the height of the drive unit is at least in the longitudinal direction of the cell. Prepare a plurality of ceramic green sheets that have a piezoelectric material as a main component and later become a piezoelectric body. In the first step and on each side of each of the plurality of ceramic green sheets, in one predetermined shape including all the regions corresponding to the drive unit and then the sidewalls, the drive electrodes are later formed. Mainly conductive materials A film (B) containing a conductive material as a main component, which is a wiring electrode for connecting to an external power source, is formed in a region corresponding to the outer peripheral portion. (A) forming a plurality of slits including slits that later become cells in a region corresponding to the drive unit in each of the plurality of ceramic green sheets, and a second step of forming by a screen printing method with a narrower width; By the formation of the slit, a third step of removing a part of the film (A) formed on the ceramic green sheet in the second step, and a plurality of films (A), a film (B) and a plurality of slits formed The ceramic green sheet is laminated by aligning the positions of a plurality of slits and pressure-bonded to obtain a ceramic green laminate, and the ceramic green laminate is fired and integrated, A fifth step of obtaining a layer fired body, the method of manufacturing the cell driving type piezoelectric actuator having a are provided.

  In the second step, the region corresponding to the driving unit and including a region that becomes a side wall afterwards is a predetermined shape that includes all of the regions that become the side walls later. In other words, it means that the region including all the side walls is included, for example, a solid shape (driving electrode) composed of one rectangle.

  In the method for manufacturing the cell driving type piezoelectric actuator according to the present invention, in the second step, the conductive material is the main component in addition to the area corresponding to the outer peripheral portion and the place where the film (B) is formed. The film (C) having a narrower width than the film (A) is preferably formed in a strip shape.

  The wiring electrode is capable of independently driving each of the plurality of cells, and is preferably separated for each of the driving electrodes included in the two side walls constituting one cell.

  In addition, it is desirable to pressurize when obtaining the ceramic green laminate in the fourth step before firing in the fifth step, but this pressurization is, for example, a material that follows unevenness on the surface of the laminate. It is preferable to use a sheet or the like. Further, in the fourth step, the ceramic green sheet that later becomes the ceiling wall and the ceramic green sheet that later becomes the substrate may be one ceramic green sheet, but a plurality of ceramic green sheets are laminated in advance. It may be what you did.

  Furthermore, in the third step (slit forming step) and the fourth step (ceramic green sheet laminating step), the manufacturing method described in JP-A-2002-160195 is applied to perform simultaneous punching lamination. Is more preferable. Without removing the punched ceramic green sheet from the mold, it is possible to repeat the operations of punching the next ceramic green sheet and stacking them at the same time to form a multilayer laminate on the mold. This is because it is possible to obtain a ceramic green sheet laminate having a low content.

  In the method for manufacturing a cell drive type piezoelectric actuator according to the present invention, the film (A) containing a conductive material as a main component later becomes a drive electrode of the manufactured cell drive type piezoelectric actuator. An electric field is applied to a piezoelectric body formed by firing a ceramic green sheet containing a piezoelectric material as a main component. The piezoelectric body is composed of individual electrodes and a common electrode. The film (A) As a signal application electrode), a common electrode (GND electrode) is alternately stacked. What is important about the film (A) is that the drive unit is not individually divided with respect to a plurality of aligned side walls, but a solid shape made up of, for example, a rectangle including all the side walls. Then, by forming a slit and then removing a part thereof, a layered individual drive electrode required to individually drive each cell can be obtained.

  In the cell drive type piezoelectric actuator according to the present invention, since the drive unit is lower than the outer peripheral part as a fired and integrated product, no separate processing or the like is required and the expansion and contraction displacement of the piezoelectric body is not hindered. Can be easily attached to applicable equipment. Not only is machining unnecessary, but it is possible to share jig parts for mounting regardless of the design shape of the actuator.

  In the method for manufacturing a cell driving type piezoelectric actuator according to the present invention, a film (A), which is to be a driving electrode later, and which is mainly composed of a conductive material, is individually applied to a plurality of aligned side walls in the driving unit. It is formed by a screen printing method as a solid drive electrode made of, for example, a rectangle including all regions including the side walls, not a segmented shape. In addition, a film (B) mainly composed of a conductive material, which becomes a wiring electrode for connecting the drive electrode to an external power source in order to independently drive each cell in the drive unit, Is formed by screen printing with a width narrower than that of the film (A). As a result, the thickness of the formed film (A) becomes slightly thinner than the film (B) due to the difference in both print patterns (shapes). And since the ceramic green sheet which formed the film | membrane (A) and the film | membrane (B) is laminated | stacked in multiple layers, the slight difference by the difference in the thickness of a film | membrane will also expand after lamination | stacking. Therefore, in the fabricated cell drive type piezoelectric actuator, the drive unit constituted by the lamination of the film (A) and the ceramic green sheet is formed lower than the outer peripheral part constituted by the lamination of the film (B) and the ceramic green sheet. Is done. Since the film (B) serves as a wiring electrode, the drive unit is not lower than all the outer peripheral parts. However, since it is lower than at least the outer peripheral portion where the wiring electrodes are laminated, as long as the produced cell drive type piezoelectric actuator is attached to the applicable device, no special processing or the like is required. It can be incorporated so as not to hinder the expansion and contraction displacement, and can be easily attached to the application device.

  In a preferred embodiment of the method for manufacturing a cell driving type piezoelectric actuator according to the present invention, a film (A) containing a conductive material as a main component in addition to a region corresponding to the outer peripheral portion and forming the film (B). ) Since the film (C) having a narrower width is formed in a strip shape, in this case, the driving unit is all composed of the film (B) or the lamination of the film (C) and the ceramic green sheet. It is formed lower than the outer peripheral part. That is, the drive part is lower than all the outer peripheral parts, and any of the outer peripheral parts can be used as the attachment part. Then, the manufactured cell drive type piezoelectric actuator can be easily attached to an applied device so as not to require a separate process or the like and to prevent the expansion and contraction displacement of the piezoelectric body.

  The manufacturing method of the cell driving type piezoelectric actuator according to the present invention is based on the difference in the pattern (shape) for printing a film made of a conductive material, in other words, by adjusting the width of the printed film. This creates a difference in the height of the laminated body, so that there is a minimum height difference between the drive unit and the outer peripheral part, which is the minimum necessary for a minute displacement (of the piezoelectric element) of the actuator. It is suitable as a means.

  In the manufacturing method of the cell driving type piezoelectric actuator according to the present invention, the film (A) is formed on the entire surface corresponding to the driving unit, and then a part thereof is removed by forming a slit. Thus, the film (A) that later becomes the drive electrode can be separated as individual drive electrodes for each piezoelectric element constituting the cell. Therefore, when a cell drive type piezoelectric actuator having a plurality of cells is manufactured, the signal application electrodes are made independent (individual electrodes) for each of the two piezoelectric elements (side walls) constituting the cell, and the individual cells are made independent. Can be driven.

  Hereinafter, embodiments of a cell driving type piezoelectric actuator and a manufacturing method thereof according to the present invention will be described with reference to the drawings. However, the present invention should not be construed as being limited thereto. Various changes, modifications, improvements, and substitutions can be added based on the knowledge of those skilled in the art without departing from the scope of the present invention. For example, the drawings show preferred embodiments of the present invention, but the present invention is not limited by the modes shown in the drawings or the information shown in the drawings. In implementing or verifying the present invention, means similar to or equivalent to those described in the specification may be applied.

  The cell drive type piezoelectric actuator according to the present invention is called a piezoelectric, but is an actuator that uses strain induced by an electric field, and in a narrow sense, a piezoelectric that generates a strain amount that is roughly proportional to an applied electric field. It is not limited to the piezoelectric actuator that uses the effect, but the electrostrictive actuator that uses the electrostrictive effect that generates a strain amount approximately proportional to the square of the applied electric field, or the polarization reversal that is found in all ferroelectric materials, Also included are actuators that utilize phenomena such as the antiferroelectric phase-ferroelectric phase transition found in antiferroelectric materials. Among the cell drive type piezoelectric actuators according to the present invention, a ceramic actuator excellent in material strength is more preferable. Further, whether or not the polarization processing is performed is appropriately determined based on the properties of the material used for the piezoelectric body of the piezoelectric element constituting the cell driving type piezoelectric actuator according to the present invention.

  In this specification, driving an actuator means driving at least one cell, and driving a cell causes displacement in a piezoelectric element forming the cell (a side wall constituting the cell), This refers to causing a change in the volume of the cell, leading to a pressurized state or a reduced pressure state in the cell.

  The cell drive type piezoelectric actuator according to the present invention includes a drive unit and an outer peripheral part located on an outer periphery of the drive unit on a substrate, and the drive unit connects two aligned side walls with a ceiling wall. And at least two side walls are composed of a piezoelectric element in which a plurality of layered piezoelectric bodies and layered electrodes are alternately stacked, and the expansion and contraction displacement is based on the longitudinal effect of the electric field induced strain of the piezoelectric element. It is an actuator that can change the volume of the cell due to the technology, at least in the longitudinal direction of the cell, the height of the drive part is lower than the outer peripheral part, and the substrate, the drive part and the outer peripheral part are integrated by firing. It has special characteristics. For such a cell drive type piezoelectric actuator, the method for manufacturing the cell drive type piezoelectric actuator according to the present invention is suitable as the manufacturing means, and the method for manufacturing the cell drive type piezoelectric actuator according to the present invention includes a manufacturing method. A special technical means capable of imparting the above technical characteristics to the cell driving type piezoelectric actuator is provided. Therefore, first, an embodiment of the method for manufacturing a cell drive type piezoelectric actuator according to the present invention will be described with reference to the drawings, and through this, a specific embodiment of the cell drive type piezoelectric actuator according to the present invention will be described. Will be shown.

  1 (a), 1 (b), and 1 (c) show the thickness of a film mainly composed of a conductive material formed on a ceramic green sheet by screen printing depending on the shape of the film. It is the figure which showed a mode that a difference arises. FIG. 1A is a plan view showing a print pattern (shape) of a film, which is a pattern (shape) composed of a film 11 and a film 12. The film 12 has a narrower pattern (shape) extending from the film 11 like a foot. The film 11 is an example of the film (A) formed on the entire surface of the region corresponding to the driving unit in the method for manufacturing the cell driving type piezoelectric actuator according to the present invention. The film 12 is the cell driving type piezoelectric actuator according to the present invention. This is an example of a film (B) having a narrower width than the film (A) formed in a region corresponding to the outer peripheral portion in the manufacturing method of the actuator. That is, the film 11 can be a drive electrode that is responsible for applying a voltage to the piezoelectric body later, and the film 12 extending therefrom has a printed pattern (shape) that can be a wiring electrode.

  1B is a diagram showing an AA ′ section in FIG. 1A, and FIG. 1C is a diagram showing a BB ′ section in FIG. Thus, when a film is formed by the printing method, the thickness of the film composed of a narrow band-shaped print pattern is larger than that of a film composed of a print pattern having a wide shape (also referred to as a solid shape) like the film 11. And become thicker. This reason is due to the plate making used in the screen printing method. A portion of the mesh where the printing paste is removed, which corresponds to the portion where the pattern is formed, is masked with an emulsion on the portion where the pattern is not formed, and the thickness of the emulsion is used to control the thickness of the pattern film. Is adjusted. At this time, the plate-making mesh is in a floating state due to the shackle by the emulsion. The printing paste on the plate making is pushed out by the squeegee rubber, but the mesh floating by the emulsion is deformed by the deflection of the squeegee rubber. In the case of a narrow pattern, the width of the emulsion foot is also narrow, so that the deformation of the mesh therebetween is also reduced. In the case of a wide pattern with a solid shape, the effect is not obtained, and at the same time the mesh is bent, the printing paste is scraped off by the squeegee rubber along the mesh. The distribution is such that the center is high and the center is low. That is, as shown in FIG. 1B, in the wide film, a thick part of the film exists at the end (boundary part) of the printed pattern, and the film is relatively thin in the other intermediate part. Become. On the other hand, as shown in FIG. 1 (c), the thickness of the thin band-like film is in a state where the thin intermediate portion in FIG. 1 (b) is narrowed and no longer exists. The film is formed only at the end, and the film is relatively thick as compared with the solid shape.

  The difference in the thickness of the film produced by such a screen printing method is only about several μm (the actual difference is further reduced because of the deformation of the electrode itself and the deformation of the ceramic green sheet itself). Therefore, the difference in the printed film thickness x the number of laminated layers = the difference in height between the drive part and the outer peripheral part is not the same), but if a large number of films having the same print pattern (shape) are stacked and laminated, The difference in thickness, that is, the difference in height, increases with the number of stacked layers. In the cell driving type piezoelectric actuator manufacturing method according to the present invention, in the second step, on one side of each of the plurality of ceramic green sheets, the entire surface corresponding to the driving unit is formed (as a solid shape) and then driven. A film (A) mainly composed of a conductive material to be an electrode is formed by a screen printing method, and a conductive electrode that becomes a wiring electrode for connecting a drive electrode to an external power source in a region corresponding to the outer peripheral portion later. Since the film (B) containing the material as a main component is formed by screen printing with a narrower width (in a strip shape) than the film (A), the cell driving type piezoelectric actuator to be manufactured has a driving part lower than the outer peripheral part. It becomes.

  FIG. 6A to FIG. 6D are diagrams showing one embodiment of a method for manufacturing a cell driving type piezoelectric actuator according to the present invention and a cell driving type piezoelectric actuator according to the present invention, respectively. 6 (a) to 6 (c) show schematic steps of an embodiment of a method for manufacturing a cell driving type piezoelectric actuator according to the present invention, and FIG. 6 (d) shows a cell driving type piezoelectric actuator according to the present invention. When the cell drive type piezoelectric actuator 60 produced by the actuator manufacturing method and corresponding to the cell drive type piezoelectric actuator according to the present invention and shown in the perspective view of FIG. 6C is cut along the cutting line 61. It is a fragmentary sectional view showing a part of section.

  The cell drive type piezoelectric actuator 60 shown in FIG. 6C and FIG. 6D is positioned on the outer periphery of the drive unit 63 on the substrate 2 on which the communication hole 8 is provided. The outer peripheral part 64 which consists of the outer peripheral part 64b is provided, and the board | substrate 2, the drive part 63, and the outer peripheral part 64 are integrated by baking. The drive unit 63 and the outer peripheral part 64 are separated by a boundary line 62 shown for convenience in FIG. 6C. The communication hole 8 may function as a nozzle in some cases. For example, when the cell driving type piezoelectric actuator 60 is used as an ink jet head, a nozzle provided on a metal plate or the like that is separately attached. It is a hole for connecting with.

  The drive unit 63 includes a plurality of cells 3 formed by connecting two side walls 6 arranged in alignment with a ceiling wall 7, and the two side walls 6 forming the cell 3 are layered with a plurality of layered piezoelectric bodies 14. The drive electrodes 18 and 19 are composed of piezoelectric elements 34 that are alternately stacked. Each of the plurality of cells 3 does not share the side wall 6 (piezoelectric element 34) and is formed independently of the adjacent cells.

  The cell drive type piezoelectric actuator 60 in this embodiment has ten layers of piezoelectric bodies 14 for each piezoelectric element 34 constituting the side wall 6. In the cell drive type piezoelectric actuator according to the present invention, the number of layers is not limited and may be appropriately determined depending on the application and purpose. However, in consideration of the stability of the actuator characteristics and ease of manufacture, the preferred number of stacked piezoelectric bodies Is 5-50 layers.

  In the cell drive type piezoelectric actuator 60, the piezoelectric body 14 constituting the piezoelectric element 34 is polarized (sandwiched) in a direction from the drive electrode 18 to the drive electrode 19 (vertical direction in FIG. 6D), for example. The polarization direction varies from layer to layer depending on the drive electrode). Then, by connecting a power source to an electrode terminal (not shown) and applying a voltage between the drive electrodes 18 and 19 with the drive electrode 18 side being positive and the drive electrode 19 side being negative, for example, the same polarization direction as described above is obtained. A directional electric field is formed. In other words, the cell driving type piezoelectric actuator 60 is formed by laminating layered piezoelectric bodies 14 having polarizations opposite to each other with the drive electrodes 18 and 19 sandwiched therebetween. Are in the same direction.

  As a result, an electric field induced strain is generated in the piezoelectric body 14, and based on the displacement due to the vertical effect of the electric field induced strain, the piezoelectric element 34 is shown in FIG. 6 (a) in a portion where the piezoelectric body 14 is sandwiched between the drive electrodes 18 and 19. d) Stretching in the vertical direction (perpendicular to the substrate 2). Since the displacement of the piezoelectric body 14 directly uses electric field induced strain, the generated force is large and the response speed is high. The amount of displacement expressed by each layer is not large, but the amount of displacement is proportional to the number of piezoelectric layers, more precisely the number of pairs of layered piezoelectric bodies and a pair of layered drive electrodes. Large displacement can be obtained by increasing the number of layers.

  In the cell drive type piezoelectric actuator 60, the thickness per layer of the piezoelectric body 14 is preferably 100 μm or less, more preferably 5 to 80 μm, so that it can be driven at a lower voltage. is there.

  The cell drive type piezoelectric actuator 60 uses the cell 3 as an ink chamber, uses two communication holes 8 provided in each cell 3 and opened in the substrate 2 as an ink introduction hole and an ejection hole. In response to the increase or decrease of the capacity, the ink is replenished from one communication hole 8 that leads to the cell 3 and then the cell 3 is similarly applied. Ink can be ejected from the other communication hole 8 that leads to. That is, the cell drive type piezoelectric actuator 60 is an actuator that can be preferably applied as an ink jet head.

  In the cell drive type piezoelectric actuator 60, the drive part 63 is lower than the outer peripheral part 64a, and is the same height as the outer peripheral part 64b. This is because the wiring electrode is formed in the region of the outer peripheral portion 64a and the wiring electrode is not formed in the region of the outer peripheral portion 64b as shown in the manufacturing method described later. Therefore, when the cell driving type piezoelectric actuator 60 is attached to a printing device or the like, it is preferable to use the higher outer peripheral portion 64a as the attaching portion.

  Hereinafter, based on FIG. 6 (a) to FIG. 6 (c), the manufacturing process of one embodiment of the manufacturing method of the cell driving type piezoelectric actuator according to the present invention will be described. In this specification, the ceramic green sheet is also simply referred to as a sheet.

  (First Step) First, ten ceramic green sheets 616 mainly composed of a piezoelectric material, and a ceramic green sheet 607 for the ceiling wall 7 that is thicker than the ceramic green sheets 607 (may be a laminate in which a plurality of thin sheets are laminated). Similarly, a ceramic green sheet 602 for a thick substrate 2 (may be a laminate in which a plurality of thin sheets are laminated) is prepared. The ceramic green sheet can be produced by a conventionally known ceramic production method. For example, a piezoelectric material powder is prepared, and a binder, a solvent, a dispersant, a plasticizer, and the like are prepared in a desired composition to prepare a slurry. After defoaming, a doctor blade method, a reverse roll coater method, a reverse A ceramic green sheet can be formed by a sheet forming method such as a doctor roll coater method.

  Next, a conductive film 618 (film made of a conductive material) having a predetermined pattern is formed on a half of the five sheets of the ceramic green sheets 616 by a screen printing method. The conductor film 619 having the pattern is formed by a screen printing method (see FIG. 6A).

  (Second Step) The printed pattern (shape) of the conductor film 618 is formed on the entire surface of the region corresponding to the drive unit 63 of the cell drive type piezoelectric actuator 60 to be manufactured, and later becomes a conductor to be the individual electrode 18. A film 618a (corresponding to the film (A)) and a part of the outer peripheral portion 64 of the cell driving type piezoelectric actuator 60 to be manufactured (the outer peripheral portion 64a) are formed on a part of the region, and then the individual electrode 18 is formed. A conductive film 618b (corresponding to the film (B)) having a narrower width than the conductive film 618a and serving as a wiring electrode for connection to an external power source is formed.

  Similarly, the printed pattern (shape) of the conductor film 619 is formed on the entire surface of the region corresponding to the drive unit 63 of the cell drive type piezoelectric actuator 60 to be manufactured, and then the conductor film 619 a ( Film (A)) and a part of the outer periphery 64 of the cell drive type piezoelectric actuator 60 to be fabricated (outer periphery 64a). The common electrode 19 is used as an external power source. A conductive film 619b (corresponding to the film (B)) having a narrower width than the conductive film 619a, which becomes a wiring electrode for connection, is formed. Although depending on the properties of the ceramic green sheet, an adhesion auxiliary layer may be added to the entire surface of the sheet in order to add a bonding force for subsequent pressure bonding.

  (Third Step) Subsequently, as shown in FIG. 6B, in the sheet 616 on which the conductor film 618 has been previously formed, it corresponds to the drive unit 63 (of the cell drive type piezoelectric actuator 60 to be manufactured). A slit 605 that later constitutes a cell and a slit 625 that later does not constitute a cell are opened in the region to be formed, and a part of the conductor film 618a is removed by forming the slits 605 and 625, whereby a sheet 614 is obtained. Similarly, in the sheet 616 on which the conductor film 619 is formed first, a slit 605 that constitutes the cell and a cell later are formed in a region corresponding to the drive unit 63 (of the cell drive type piezoelectric actuator 60 to be manufactured). A slit 625 that is not configured is opened, and by forming the slits 605 and 625, a part of the conductor film 619a is removed to obtain a sheet 615.

  Later, a slit 625 that does not constitute a cell is opened in the sheet 607 that becomes the ceiling wall 7 later, and the pores 43 are opened in the sheet 602 that becomes the substrate 2 later. The pores 43 are holes that will later become the communication holes 8, and are provided two by two at positions where the sheets 602 communicate with the slits 605 of the sheets 614 and 615 when the sheets 602 are stacked with the sheets 614 and 615.

  The substantial part of the sheet between the slits 605 and 625 in the sheets 614 and 615 later constitutes the side wall 6 (piezoelectric body 14) of the cell driving type piezoelectric actuator 60. The conductor film 618 of the sheet 614 is formed so as to cover at least the sheet surface between the slit 605 and the slit 625, and as described above, a part thereof later constitutes the individual electrode 18 and the individual electrode 18 is formed. Used as a wiring electrode connected to an external power source. The conductive film 619 of the sheet 615 is formed so as to cover at least the sheet surface between the slit 605 and the slit 625, and as described above, a part thereof later constitutes the common electrode 19 and the common electrode 19. Used as a wiring electrode connected to an external power source.

  (Fourth Step) Next, the sheets 614 and 615 are alternately laminated and pressed to obtain a ceramic green laminate having a plurality of slit-like through holes (not shown). Then, a ceramic green laminate having a plurality of slit-like through holes is sandwiched between the sheet 607 and the sheet 602 and laminated to obtain a ceramic green laminate (not shown) having a predetermined thickness. In addition, it is preferable to perform the lamination using a sheet of a material that follows the irregularities on the surface of the ceramic green laminate. This is because problems such as buckling and bending are unlikely to occur in the side wall (piezoelectric element) of the drive unit. In the obtained ceramic green laminate, a plurality of slit-like through-holes are built in which a plurality of slits 605 formed in each of the sheets 614 and 615 laminated one by one are connected.

  (Fifth Step) Next, the ceramic green laminated body is fired and integrated to obtain a laminated fired body (not shown). In the obtained laminated fired body, a built-in slit-like through hole formed by communicating the slits 605 of the sheets 614 and 615 is fired to form the cell 3. Four cells 3 are provided in one row. Next, the conductor films 618b and 619b are fired, and terminal electrodes (not shown) are formed so as to be connected to the wiring electrode portions (omitted in FIG. 6C) that appear on both end faces of the laminated fired body. And if a polarization process is performed as needed, the cell drive type piezoelectric actuator 60 will be obtained.

  As described above, in the cell drive type piezoelectric actuator 60, the drive part 63 is not lower than all the outer peripheral parts 64, but at least in the longitudinal direction of the cell, it is lower than the outer peripheral part 64a. The height is equivalent. This is because the wiring electrodes (conductor films 618b and 619b) were formed in the region of the outer peripheral portion 64a, but not formed in the region of the outer peripheral portion 64b. In order to make all of the outer periphery of the drive unit higher than the drive unit and lower all of the drive unit lower than the outer periphery, in the second step, with respect to the sheets 614 and 615, the regions corresponding to the outer periphery 64 and the conductor films 618b and 619b ( In addition to the place where the film (B) is formed, the conductor film (corresponding to the film (C)) may be formed in a band shape with a narrower width than the conductor film 618a.

  FIG. 3A and FIG. 3B are plan views showing an example of a ceramic green sheet in which a conductor film is formed in a strip shape by a printing method, in addition to a place where a drive electrode and a wiring electrode are formed. The printed pattern (shape) of the conductor film of the sheet 314 shown in FIG. 3A is formed on the entire surface corresponding to the drive unit of the cell drive type piezoelectric actuator to be manufactured, and later becomes an individual electrode. Conductor film 318a (corresponding to film (A)) and a wiring electrode for connecting an individual electrode to an external power source, which is formed in a region corresponding to a part of the outer peripheral portion of the cell drive type piezoelectric actuator to be manufactured. In addition, the conductor film 318b (corresponding to the film (B)) having a narrower width than the conductor film 318a, and in addition, a band-shaped conductor formed in a region corresponding to the outer peripheral portion other than the place where the conductor film 318b is formed. A film 318c (corresponding to film (C)) is formed.

  The printed pattern (shape) of the conductor film of the sheet 315 shown in FIG. 3B is formed on the entire surface corresponding to the drive unit of the cell drive type piezoelectric actuator to be manufactured, and later becomes a common electrode. Conductive film 319a (corresponding to film (A)) and a wiring electrode for connecting a common electrode to an external power source, which is formed in a region corresponding to a part of the outer peripheral portion of the cell drive type piezoelectric actuator to be manufactured. In addition, the conductor film 319b (corresponding to the film (B)) having a narrower width than the conductor film 319a, and in addition, a band-shaped conductor formed in a region corresponding to the outer peripheral portion other than the place where the conductor film 319b is formed. A film 319c (corresponding to film (C)) is formed.

  When the sheets 314 and 315 are laminated, the laminated portions of the conductor films 318b and 319b and the laminated portions of the conductor films 318c and 319c constitute an outer peripheral portion, and the laminated portions of the conductor films 318a and 319a constitute a driving unit. FIG. 2 is a cross-sectional view of a state in which the sheets 314 and 315 are arranged in the order of lamination. In FIG. 2, in the laminated sheets 314 and 315, the strip-like conductor films 318c and 319c are thinner than the conductor films 318a and 319a, as in the conductor films 318b and 319b. The drive part equivalent part 23 which becomes the part is lower than the peripheral part equivalent part 24 which becomes the outer peripheral part of the cell drive type piezoelectric actuator. The same applies to the cross section on the side that does not appear in FIG. 2, and the drive portion equivalent portion 23 is lower than all the outer peripheral portion equivalent portions 24.

  FIG. 5 is a cross-sectional view showing another embodiment of the cell drive type piezoelectric actuator according to the present invention, and FIG. 4 shows a sheet used for manufacturing the cell drive type piezoelectric actuator 40 shown in FIG. It is a top view of the sheet | seat in which the conductor film used as an individual electrode was formed. FIG. 7 is a plan view showing a slit pattern showing the shape and position of a slit including a slit that is later formed in a sheet and later constitutes a cell.

  As shown in FIG. 4, in the sheet 414, the printed pattern (shape) of the conductor film formed on the sheet 414 is an area corresponding to the driving unit of the cell driving type piezoelectric actuator 40 to be manufactured. Formed in a region corresponding to a part of the outer peripheral portion of the cell drive type piezoelectric actuator 40 to be manufactured, and a conductor film 418a (corresponding to the film (A)) to be an individual electrode later. In addition to the conductive film 418b having a narrower width (corresponding to the film (B)), which is a wiring electrode for connecting the individual electrode to the external power source, and the region corresponding to the outer peripheral portion, the conductive film 418b is formed at a place other than the place where the conductive film A band-shaped conductor film 418c (corresponding to the film (C)) and a gap between these conductor films are filled with a piezoelectric paste 45 made of the same material as the piezoelectric body.

  In addition to the sheet 414, a sheet on which a conductor film to be an individual electrode is formed in accordance with the sheet 315 is prepared, and a sheet to be a substrate and a ceiling wall are formed according to the slit pattern shown in FIG. The cell driving type piezoelectric actuator 40 is obtained by alternately laminating and firing between the sheets. The obtained cell driving type piezoelectric actuator 40 is provided with a driving unit 53 and an outer peripheral part 54 positioned on the outer periphery thereof on the substrate 2, and in the drawing, two vertically long side walls made of piezoelectric elements are arranged on the ceiling wall. 7 is an actuator that has seven cells connected to each other and whose cell volume changes due to expansion and contraction of the piezoelectric element. As shown in FIG. 5, in the cell driving type piezoelectric actuator 40, the driving unit 53 is lower than the outer peripheral part 54 as a result of laminating the sheets 414 and the like.

  As mentioned above, although each embodiment was described about the manufacturing method of the cell drive type piezoelectric actuator which concerns on this invention, and the cell drive type piezoelectric actuator which concerns on this invention, it used for the cell drive type piezoelectric actuator which concerns on this invention next. The material to be used will be described.

  First, a piezoelectric material (piezoelectric material) will be described. Any material can be used as long as it causes electric field induced strain such as piezoelectric effect or electrostrictive effect. It may be crystalline or amorphous, and it is also possible to use semiconductor ceramics, ferroelectric ceramics, or antiferroelectric ceramics. What is necessary is just to select suitably according to a use and to employ | adopt. Moreover, even if it is a material which requires a polarization process, the material which is not required may be sufficient.

  Specifically, preferable materials include lead zirconate, lead titanate, lead magnesium niobate, lead nickel niobate, lead nickel tantalate, lead zinc niobate, lead manganese niobate, lead antimony stannate, manganese tungstic acid. Lead, lead cobalt niobate, lead magnesium tungstate, lead magnesium tantalate, barium titanate, sodium bismuth titanate, bismuth neodymium titanate (BNT), potassium sodium niobate, strontium bismuth tantalate, barium copper tungsten, iron acid Bismuth or a composite oxide composed of two or more of these can be given. These materials include lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, cerium, cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, lithium, bismuth, tin, An oxide such as copper may be dissolved.

  Furthermore, lithium bismutate or lead germanate is added to a material obtained by adding lithium bismutate, lead germanate, or the like to the above materials, for example, a composite oxide of lead zirconate, lead titanate, and lead magnesium niobate. Such a material is preferable because it can exhibit high material properties while realizing low-temperature firing of the piezoelectric body. The low-temperature firing of the piezoelectric material can also be realized by adding glass (for example, silicate glass, borate glass, phosphate glass, lead germanate glass, or a mixture thereof). However, excessive addition leads to deterioration of material characteristics, so it is desirable to determine the addition amount according to required characteristics.

  Next, a conductive metal is employed as a material for the electrodes (drive electrodes, wiring electrodes, dummy electrodes, etc.). For example, simple metals such as aluminum, titanium, chromium, iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium, rhodium, silver, tin, tantalum, tungsten, iridium, platinum, gold, or lead, or these It is preferable to use an alloy composed of two or more types, for example, one of silver-platinum, platinum-palladium, silver-palladium, etc., alone or in combination of two or more. Also, a mixture or cermet of these materials and aluminum oxide, zirconium oxide, titanium oxide, silicon oxide, cerium oxide, glass, piezoelectric material, or the like may be used. In selecting these materials, it is preferable to select them according to the type of piezoelectric material.

  The cell drive type piezoelectric actuator according to the present invention can be suitably used as an inkjet head of a printing device. In addition, micro-pumps, micro-droplet dispensing devices used in the manufacturing process of DNA chips and semiconductor manufacturing coatings necessary for mixing and reacting with trace amounts of liquids in the biotechnology field and analyzing the genetic structure, and in the medical field The present invention can be used as an actuator for a small amount of reagent supply device used in various tests.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining one embodiment of a method for manufacturing a cell driving type piezoelectric actuator according to the present invention, and FIG. 1 (a) is a plan view showing a printed pattern (shape) of a film; FIG. 1B is a diagram showing a section AA ′ in FIG. 1A, and FIG. 1C is a diagram showing a section BB ′ in FIG. FIG. 3 is a diagram for explaining an embodiment of a method for manufacturing a cell driving type piezoelectric actuator according to the present invention, and is a cross-sectional view showing a thickness distribution of a film printed on a ceramic green sheet in a stacking direction of the ceramic green sheets It is. FIG. 3 is a diagram for explaining one embodiment of a method for manufacturing a cell driving type piezoelectric actuator according to the present invention, and FIG. 3A is an example of a ceramic green sheet (individual electrode forming sheet) on which a strip-shaped conductor film is formed. ) And FIG. 3B is a plan view showing another example (common electrode forming sheet). It is a top view of the sheet | seat in which the conductor film used as an individual electrode was formed among the sheets used in order to produce the cell drive type piezoelectric actuator shown by FIG. It is sectional drawing which shows one Embodiment of the cell drive type piezoelectric actuator which concerns on this invention. It is a schematic process explanatory drawing which shows one Embodiment of the manufacturing method of the cell drive type piezoelectric actuator of this invention, and a perspective view which shows one Embodiment of the cell drive type piezoelectric actuator of this invention. . It is a figure explaining the manufacturing method of the cell drive type piezoelectric actuator which concerns on this invention, and is a top view showing the slit pattern for the punching of a ceramic green sheet.

Explanation of symbols

40, 60 ... cell drive type piezoelectric actuator, 2 ... substrate, 3 ... cell, 6 ... side wall, 7 ... ceiling wall, 8 ... communication hole, 14 ... piezoelectric body, 18, 19 ... drive electrode, 23 ... drive part equivalent part 24 ... Piezoelectric element, 45 ... Piezoelectric paste, 53, 63 ... Drive part, 54, 64 ... Outer part, 61 ... Cutting line, 314, 315, 414, 602, 607, 614, 615 616, ceramic green sheet, 605, 625, slit, 618, 619, conductor film.

Claims (9)

On the substrate, there is a drive unit and an outer peripheral part located on the outer periphery,
The driving unit includes a plurality of cells formed by connecting two aligned side walls with a ceiling wall, and a plurality of layered piezoelectric bodies and layered driving electrodes are alternately stacked on at least the two side walls. The volume of the cell can be changed by expansion and contraction displacement based on the longitudinal effect of the electric field induced strain of the piezoelectric element.
A cell drive type piezoelectric actuator in which the height of the drive unit is lower than the outer peripheral part at least in the longitudinal direction of the cell, and the substrate, the drive unit, and the outer peripheral part are integrally fired.   The difference in height between the driving portion and the outer peripheral portion is larger than the expansion / contraction displacement of the piezoelectric element, and is ½ or less of the thickness per layer of the layered piezoelectric body constituting the piezoelectric element. The cell driving type piezoelectric actuator according to claim 1.   In the outer peripheral portion, a wiring electrode connected to the driving electrode for applying a driving voltage to the piezoelectric element and a band-shaped dummy electrode having a width of 200 μm or less are sandwiched between a plurality of layered piezoelectric bodies, The cell driving type piezoelectric actuator according to claim 1, wherein the cell driving type piezoelectric actuator is formed so as to surround an outer periphery of the driving unit.   4. The cell driving according to claim 1, wherein in the piezoelectric element constituting the side wall in the driving unit, all of the plurality of layered driving electrodes are exposed on a side surface of the side wall. 5. Type piezoelectric actuator.   5. The cell drive type piezoelectric actuator according to claim 4, wherein the exposed end face of the layered drive electrode is a surface fired after fracture by punching.   The cell driving type piezoelectric actuator according to claim 1, wherein an insulating film is formed on an inner wall of the cell in the driving unit. A driving unit and an outer peripheral part located on the outer periphery of the driving unit are provided on a substrate, and the driving unit includes a plurality of cells formed by connecting two aligned side walls with a ceiling wall, and at least the two One side wall is composed of a piezoelectric element in which a plurality of layered piezoelectric bodies and layered drive electrodes are alternately stacked, and at least in the longitudinal direction of the cell, the height of the drive unit is lower than the outer peripheral part, and A cell drive type piezoelectric actuator in which the substrate, the drive unit, and the outer peripheral part are integrally fired,
A first step of preparing a plurality of ceramic green sheets comprising a piezoelectric material as a main component and later becoming the piezoelectric body;
On one side of each of the plurality of ceramic green sheets, a conductive material, which is a region corresponding to the drive unit and includes a region that is to be a side wall later, and that later includes the drive electrode, A film (B) containing a conductive material as a main component is formed in the region corresponding to the outer peripheral portion and serves as a wiring electrode for connection to an external power source while the film (A) containing the main component is formed by screen printing. A second step of forming by a screen printing method with a narrower width than the film (A);
A plurality of slits including a slit to be the cell later are formed in a region corresponding to the driving unit in each of the plurality of ceramic green sheets, and the slit is formed to form the ceramic green sheet in the second step. A third step of removing a part of the film (A),
A fourth step of obtaining a ceramic green laminate by laminating the plurality of ceramic green sheets formed with the films (A) and (B) and the slits, aligning the positions of the plurality of slits, and press-bonding;
And a fifth step of obtaining the laminated fired body by firing and integrating the ceramic green laminated body.   In the second step, a film having a narrower width than the film (A), the main component being a conductive material, in addition to a region corresponding to the outer peripheral portion and forming the film (B). The method for manufacturing a cell driving type piezoelectric actuator according to claim 7, wherein C) is formed in a strip shape.   The cell drive according to claim 7, wherein the wiring electrode is capable of independently driving each of the plurality of cells, and is separated for each drive electrode included in two side walls constituting one cell. Method for manufacturing a piezoelectric actuator.

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