JP2003069100A - Piezoelectric transducer element, its working method, and actuator using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric transducer element the joint surface of which is prevented from being peeled off from another member even when the element is driven at a high speed for a long time by improving the adhesive strength between the element and member, and to provide a method of working the joint surface and an actuator using the element. SOLUTION: A sheet-like piezoelectric element 11 is formed by using a piezoelectric ceramic-based piezoelectric material and first and second electrodes 12 and 13 composed of platinum-based electrode materials are respectively formed on the front and rear surfaces of the element 11. Then the material 11 is folded double at a folding section 14 and the folded element 11 is wound into a columnar shape by laminating the folded half bodies of the element 11 upon another. Then the columnar body is dipped in an etchant which dissolves the PZT used for forming the element 11, but does not dissolve platinum. Since only the PZT exposed on the dipped end section of the piezoelectric transducer element which becomes the joint surface is etched, an uneven surface on which the first and second electrodes 12 and 13 are protruded from the portion of the piezoelectric element 11 is formed in the end section, and the adhesive strength between the transducer element and another member can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a piezoelectric conversion element.

[0002]

2. Description of the Related Art An actuator using a piezoelectric conversion element has a high conversion efficiency for converting supplied electric energy into a driving force, a large driving force is generated in spite of its small size and light weight, and the driving force is easily controlled. Therefore, it has come to be used for driving and positioning driven members of cameras, measuring instruments, and other precision machines.

As a piezoelectric conversion element which is a driving source used in such an actuator, a sheet-shaped thin plate piezoelectric element made of a ceramics piezoelectric material and an electrode body serving as a positive electrode and a negative electrode (hereinafter, simply referred to as an electrode) There are proposed a plurality of laminated sheets, a sheet-shaped thin plate piezoelectric element, and a laminated body in which electrodes are laminated and wound in a hollow cylindrical shape.

FIG. 25 and FIG. 26 show the structure of an actuator using a sheet-shaped thin plate piezoelectric element made of a ceramic-based piezoelectric material and a piezoelectric conversion element made by laminating a plurality of positive and negative electrodes. FIG. 25 is a perspective view showing an assembly process, and FIG. 26 is a perspective view showing a completed actuator.

As shown in FIG. 25, in the actuator, one end of the piezoelectric conversion element 102 is adhered and fixed on the fixed member 101 with an adhesive 104, and the driven member 103 is attached to the other end of the piezoelectric conversion element. Is similarly fixed by an adhesive 104.

In this structure, as shown in FIG.
When a pulsed voltage is applied or a pulsed current is supplied between the positive electrode 105 and the negative electrode 106, the piezoelectric conversion element 102 expands and contracts in the thickness direction (stacking direction), and the speed is increased in the expansion direction and the contraction direction. Different stretching vibrations are generated, and the driven member 1 is adhesively fixed to the end of the piezoelectric conversion element 102.
The stretching vibration is transmitted to 03. Thereby, for example, when a moving body (not shown) is brought into frictional contact with the driven member 103, the moving body can be moved in a predetermined direction.

In addition, by adjusting the voltage applied to the piezoelectric conversion element or the current supplied, it is possible to cause the driven member to move in various vibration modes.

In the actuator having the above-mentioned structure, an adhesive agent such as an epoxy adhesive agent is used for joining the fixing member 101 and the piezoelectric conversion element 102 and joining the piezoelectric conversion element 102 and the driven member 103. However, there is an inconvenience that the joint portion is peeled off by the vibration generated in the piezoelectric conversion element. As a countermeasure against this, an end surface of ceramics, which is a bonding surface of the piezoelectric conversion element, is subjected to etching processing to make it a rough surface to increase the adhesive strength.

[0009]

However, even if the end faces of the ceramics, which are the bonding surfaces of the piezoelectric conversion element, are roughened by etching, the bonding strength cannot be sufficiently increased, and the piezoelectric conversion element is operated at high speed for a long time. There was the inconvenience that the adhesive was peeled off when driving. The present invention is intended to solve the above problems.

[0010]

The present invention is to solve the above-mentioned problems. The invention of claim 1 is a laminated body in which a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material and an electrode body are laminated. In the configured piezoelectric conversion element, the joint surface for adhering and fixing the piezoelectric conversion element to another member is a surface formed on an uneven surface on which either one of the piezoelectric element and the electrode body projects. It is a piezoelectric conversion element.

Further, the joint surface is a surface formed as a concavo-convex surface by selectively etching one of the piezoelectric element and the electrode body which are both exposed to the joint surface.

In this case, the joint surface is a surface formed by a concave-convex surface where the piezoelectric element is concave and the electrode body is convex by performing a selective etching process in which the piezoelectric element is etched and the electrode body is not etched. It may be.

Further, the joint surface is a surface formed by an uneven surface where the electrode body is etched and the piezoelectric element is not etched, and the piezoelectric element is convex and the electrode body is concave. May be.

In addition, the joint surface is formed as an uneven surface in which the piezoelectric element and the electrode body, which are both exposed to the joint surface, are selectively sputtered to make the piezoelectric element convex and the electrode body concave. It may be a face.

The piezoelectric conversion element may be a piezoelectric conversion element formed into a columnar body or a cylindrical body by rolling up a laminated body in which a sheet-shaped piezoelectric element composed of a ceramics piezoelectric material and an electrode body are rolled up. Good.

Further, the piezoelectric conversion element is a laminated body in which a sheet-shaped piezoelectric element made of a ceramics-based piezoelectric material and an electrode body are laminated, and a piezoelectric conversion element in which displacement occurs in a direction perpendicular to a voltage application direction. May be

The thickness (aspect ratio) of the electrode body with respect to the depth of the depression is preferably 5 or less.

According to a ninth aspect of the present invention, the piezoelectric conversion element in the piezoelectric conversion element composed of a laminated body in which a sheet-shaped piezoelectric element composed of a ceramics-based piezoelectric material and an electrode body are laminated is bonded to another member by bonding. A method of processing a surface,
It is a method of processing a piezoelectric conversion element, characterized in that either one of the piezoelectric element and the electrode body, which are both exposed on the joint surface, is selectively corroded to form an uneven surface.

In this case, the method for processing the joint surface may be a selective etching process in which the piezoelectric element is etched and the electrode body is not etched, or a selective etching process in which the electrode body is etched and the piezoelectric element is not etched. May be Furthermore, the processing method of the bonding surface may be a selective sputtering processing in which the electrode body is selectively processed by sputtering and the piezoelectric element is not processed.

According to a tenth aspect of the present invention, the piezoelectric conversion element according to any one of the first to eighth aspects, a fixing member for fixing the piezoelectric conversion element, and a driving member fixed to the piezoelectric conversion element. In the actuator using the piezoelectric conversion element including the driven member driven by the driving member, the joint between the piezoelectric conversion element and the fixing member and the driving member is an uneven surface formed on the piezoelectric conversion element. It is an actuator using a piezoelectric conversion element, characterized in that an adhesive is applied to the joint surface to be joined.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

[First Embodiment] The piezoelectric conversion element of the first embodiment is such that one sheet-shaped piezoelectric element made of a piezoelectric ceramic-based piezoelectric material has an electrode body (hereinafter, simply referred to as an electrode) on both front and back surfaces. Is formed and is rolled up to form a columnar body.

FIG. 1 is a perspective view showing a piezoelectric element which is a material of the piezoelectric conversion element of the first embodiment, FIG. 2 is a perspective view in which the piezoelectric element which is a material is folded in two, and FIG. It is a perspective view showing the appearance of the piezoelectric conversion element formed in the body. For convenience of explanation, the thicknesses of the piezoelectric element and the electrode body are shown to be significantly enlarged compared to the actual thickness.

The piezoelectric conversion element 10 is a sheet-shaped piezoelectric element 1 made of a piezoelectric ceramic-based piezoelectric material.
1 is formed, and the first electrode 12 and the second electrode 13 are formed on the front surface and the back surface thereof. Next, it is folded in two at approximately the center, and rolled up so that the piezoelectric elements are laminated with each other around the bent portion 14 to form a columnar body.

After that, a firing process, a cutting process for cutting the end of the columnar body, and an etching process for the cut surface are performed. Further, the piezoelectric conversion element 10 is completed through the processing of connecting the lead wires to the first electrode 12 and the second electrode 13 exposed on the outer peripheral surface of the columnar body, and the polarization treatment.

The manufacturing process of the piezoelectric conversion element 10 will be described.
First, as the material of the piezoelectric element 11, PZT (PbZr
Piezoelectric ceramics containing O ₃ · PbTiO ₃ as the main component are used. This ceramic powder is mixed with a solvent, a dispersant, a binder, a plasticizer, etc., and made into a uniform flat surface using a blade or the like to have a constant thickness, for example, 20 to 100 μm.
Stretch to the thickness of. When the solvent is evaporated and dried, a flexible sheet called a green sheet can be obtained.

Next, on both the front and back surfaces of this green sheet (piezoelectric element), a material in which a platinum (Pt) -based electrode material is pasted with an appropriate resin binder by means of screen printing or the like has a predetermined thickness, for example, 7 The first electrode 12 and the second electrode 13 are formed by printing with a thickness of about 10 μm and cut into a predetermined size (see FIG. 1).

Next, it is folded in two at the substantially central portion (see FIG. 2), and rolled up so that the piezoelectric elements are laminated around the bent portion 14 to form a columnar body (see FIG. 3).

At this time, as shown in FIG. 4, a winding shaft 17 having slits 18 formed in the axial direction is prepared, and a sheet-shaped sheet having the first electrode 12 and the second electrode 13 formed on both front and back surfaces thereof is prepared. Alternatively, the central portion of the piezoelectric element 11 may be sandwiched between the slits 18 of the winding shaft 17, and the piezoelectric elements may be rolled up so as to be stacked on each other to form a tubular body.

In the columnar body (or tubular body, hereinafter, for convenience of explanation, both of them are referred to as columnar bodies) having this structure, as is apparent from FIG. 3, the first electrode 12 and the first electrode 12 are provided on the outer peripheral surface of the columnar body. Two
The electrode 13 is exposed, and the end faces of the first electrode 12 and the second electrode 13 are exposed in a spiral shape on both end faces of the columnar body in the axial direction.

Next, the rolled columnar body is fired under a predetermined temperature condition. The temperature condition for firing is, for example, as shown in FIG.
As shown in, the temperature was gradually raised to 500 ° C over about 5 hours, and after firing at 500 ° C for a certain time, 9
After a while, the temperature is gradually increased up to 1200 ° C. further,
After firing at 1200 ° C. for about 0.3 hours, it is cooled to room temperature over about 6 hours. In this embodiment, the thickness of the piezoelectric element after firing is about 50 μm and the thickness of the electrode is about 5 μm.

In order to finish the above-mentioned fired columnar body 10 to a desired length dimension and to carry out an etching process which will be described later, both ends of the columnar body 10 in the axial direction are cut. The cutting process is performed by a cutting device that rotates a cutter having cemented carbide powder adhered to the outer peripheral surface of a rotating disk at high speed, which is generally called a dicer. FIG. 6 is a diagram for explaining the cutting process of both axial end portions of the columnar body 10, and the axially end faces 10a and 10b of the columnar body 10 after the cutting process are finished surfaces close to mirror surfaces.

Next, the etching process of the end face of the columnar body 10 will be described. FIG. 7 is a diagram showing the concept of etching processing. As described above, the columnar body 10 cut and processed
The end faces 10a and 10b in the axial direction of the spiral PZT
The piezoelectric element 11 made of, and the first electrode 12 and the second electrode 13 made of a platinum (Pt) -based electrode material are exposed, and the outer peripheral surface of the columnar body is made of the platinum (Pt) -based electrode material. Also, since it is covered with the second electrode 13, an etching solution 19 in which PZT, which is the material of the piezoelectric element, is dissolved and platinum (Pt) is not dissolved, for example, nitric acid and hydrofluoric acid are mixed.
By using, it is possible to selectively etch only PZT, which is the piezoelectric element portion exposed on the end faces 10a and 10b.

FIG. 8 shows the columnar body 10 before and after etching.
8A and 8B are enlarged cross-sectional views for explaining the state of the end face of FIG. 8A shows the state of the end face of the columnar body 10 before etching, and FIG. 8B shows the state of the end face after etching. ing.

That is, before the columnar body 10 is dipped in the etching liquid 19, the end face of the piezoelectric element 11 (the upper face in FIG. 8) and the first
The electrode 12 and the end surface of the second electrode 13 (the upper surface in FIG. 8) are on the same plane. When immersed in the etching liquid 19, the outer peripheral surface of the columnar body covered with the first electrode 12 and the second electrode 13 remains as it is without being etched. Further, the end faces 10a and 10b of the columnar body are the first electrodes 1 exposed on the end faces.
The portions of 2 and the second electrode 13 remain as they are without being etched, and only the piezoelectric element 11 exposed on the end face is etched, and the end faces of the first electrode 12 and the second electrode 13 project from the end face of the piezoelectric element 11. An uneven surface is formed.

Since the etching process of the columnar body 10 is completed, the lead wires are connected to the first electrode 12 and the second electrode 13 and the polarization process is completed to complete the piezoelectric conversion element.

Next, the joining process between the piezoelectric conversion element and another member when manufacturing the actuator using the piezoelectric conversion element manufactured in the above process will be described.

Here, vibrations having different expansion and contraction speeds in the axial direction are generated in the driving member by the expansion and contraction vibrations in the axial direction of the columnar piezoelectric conversion element, and the moving body frictionally coupled to the driving member is moved in a predetermined direction. The actuator to be activated will be described.

First, the structure of an actuator using a piezoelectric conversion element will be described. FIG. 9 is a sectional view of the actuator 20, in which one end surface 10 of the piezoelectric conversion element 10 is fixed to the fixing member 21.
a is adhered and fixed with an adhesive 24, and the carbon shaft 23 as a driving member is attached to the other end surface 10b of the piezoelectric conversion element with the adhesive 24.
Use adhesive to fix. The carbon shaft 23 is supported by the supporting portions 21 a and 21 b provided on the fixing member 21 so as to be movable in the axial direction.

When the moving body 27 is frictionally coupled to the carbon shaft 23 with an appropriate frictional force and a driving pulse is supplied from the driving pulse generating circuit 25 between the first electrode 12 and the second electrode 13 of the piezoelectric conversion element 10, Stretching vibrations having different axial expansion and contraction speeds are generated in the piezoelectric conversion element 10, and are transmitted to the carbon shaft 23. Due to the stretching vibration of the carbon shaft 23, the moving body 27 frictionally coupled to the carbon shaft 23 moves in the slow vibration direction, for example, the direction of arrow a.

The joining process of the piezoelectric conversion element 10, the fixing member 21 and the carbon shaft 23 which is the driving member will be described. In this embodiment, an epoxy adhesive is used as the adhesive 24. Since the first electrode 12 and the second electrode 13 are exposed on the end faces 10a and 10b of the piezoelectric conversion element 10, if the conductive carbon shaft 23 is adhered and fixed by the adhesive 24, the electrodes may be short-circuited. is there.

Therefore, in order to form an insulating layer between the end surface 10a of the piezoelectric conversion element and the fixing member 21 and between the end surface 10b of the piezoelectric conversion element and the carbon shaft 23, a diameter of about 20 is obtained.
Adhesive 2 containing approximately 10% by volume of glass particles of μm 2
Use 4 The diameter of the glass particles is about 5 to 50μ.
When m and the mixing ratio were 5 to 50% by volume, almost the same effect was obtained. Further, as the material for forming the insulating layer, not only glass particles but also particles of synthetic resin were able to obtain the same effect.

The end face 10 serving as the joint face of the piezoelectric conversion element 10.
Since a and 10b are processed into the concavo-convex shape in which the first electrode 12 and the second electrode 13 are projected from the piezoelectric element 11 by the above-described etching process, the concavo-convex pattern is larger than the conventional one in which the end surface is simply roughened. Is large and can be joined more firmly than conventional ones.

Next, a comparative test of the adhesive strength of the joint surfaces will be described. FIG. 10 shows a structure in which the PZT (in this case, the structure in which the electrodes are not exposed on the end surface) is exposed on the end surface in the axial direction of the piezoelectric conversion element. FIG. 11A is a diagram showing the adhesive strength when the end face and the carbon shaft are adhered by an epoxy adhesive, and FIG. 10A shows a case where no processing is applied to the end face in the axial direction of the piezoelectric conversion element. Strength is approximately 160 kgf / c
m ² indicates the degree, if (b) in FIG. 10 is obtained by etching the end face in the axial direction, the adhesive strength is approximately 180 kgf / c
It shows about m ² .

Further, FIG. 11 shows a structure in which the PZT and the electrode are exposed on the axial end surface of the piezoelectric conversion element, and the axial end surface of the piezoelectric conversion element and the carbon shaft are bonded with an epoxy adhesive. FIG. 11A is a diagram showing the adhesive strength in the case of performing the above. FIG. 11A shows a case where no processing is applied to the axial end surface (PZT and the electrode are exposed) of the piezoelectric conversion element, and the adhesive strength is approximately 180 kgf / cm ^2. 11B shows the case where the axial end surface (PZT and the electrodes are exposed) of the piezoelectric conversion element is selectively etched, and the adhesive strength is about 300 kgf / cm ² or more.

As is apparent from FIGS. 10 and 11, it can be seen that the adhesive strength is remarkably improved by selectively etching the axial end surface (PZT and the electrode exposed) of the piezoelectric conversion element.

FIG. 12 shows the relationship between the etching depth and the adhesive strength. The horizontal axis represents the aspect ratio obtained by dividing the depth of the recess formed by the etching by the electrode thickness, and the vertical axis represents the adhesive strength. I took it and showed it.

As is clear from FIG. 12, when the aspect ratio is 5 or less, the adhesive strength is about 180 kgf / cm ² or more, and when the aspect ratio becomes too large, the adhesive strength decreases.

[Second Embodiment] In the piezoelectric conversion element of the second embodiment, a sheet-shaped piezoelectric element made of a piezoelectric ceramics piezoelectric material is used, and the first electrode 12 is provided between the piezoelectric elements.
And the second electrode 13 is alternately sandwiched and laminated to form a piezoelectric conversion element.

The piezoelectric conversion element 30 of the second embodiment is also
Manufacture of green sheets, formation of first and second electrodes,
The steps of stacking, firing, cutting the edges of the stack, etching the cut surface, connecting lead wires to the electrodes, and polarization are performed. In the manufacturing process of the first embodiment, the laminated body folded in two is rolled up into a columnar body, whereas in the second embodiment it is different in that it is simply laminated, but the other steps are Since it is the same as the piezoelectric conversion element according to the first embodiment, the same members are designated by the same reference numerals and detailed description thereof will be omitted.

In FIG. 13, as described above, the sheet-shaped piezoelectric element made of the piezoelectric ceramics-based piezoelectric material and the first electrode 12 and the second electrode 13 made of the platinum (Pt) -based electrode material are alternately sandwiched and laminated. In the following description, it may be referred to as a laminated body 30 in a perspective view showing the configuration of the piezoelectric conversion element (laminated body) 30 configured as described above. After firing the laminated body 30 at a predetermined temperature, the exposed ends of the first electrode 12 and the second electrode 13 are cut and processed by a cutting device called a dicer.

Next, the etching process of the cut surface of the laminate 30 will be described. End surface 30 of the laminated body that has been cut
a is a finished surface close to a mirror surface, and the end face of the piezoelectric element 11 and the end faces of the first electrode 12 and the second electrode 13 made of a platinum (Pt) -based electrode material are exposed. Only PZT, which is the piezoelectric element portion exposed on the end face 30a, is selectively etched with an etching solution in which a certain PZT is dissolved and platinum (Pt) is not dissolved, for example, nitric acid and hydrofluoric acid.

FIG. 14 shows the laminated body 3 before and after the etching process.
14A is an enlarged cross-sectional view for explaining the state of the end face of FIG. 0, FIG. 14A shows the state of the end face before etching, and FIG.
(B) shows the state of the end face after etching.

That is, before the laminated body 30 is immersed in the etching solution, the end surface of the piezoelectric element 11 (upper surface in FIG. 14) and the end surfaces of the first electrode 12 and the second electrode 13 (upper surface in FIG. 14) are flush with each other. It is above. When immersed in an etching solution, the first electrode 1
The portions of 2 and the second electrode 13 are left as they are without being etched, and only the end faces of the piezoelectric element 11 are etched to form an uneven surface in which the end faces of the first electrode 12 and the second electrode 13 project from the end face of the piezoelectric element 11. To be done.

[Third Embodiment] In the piezoelectric conversion element of the third embodiment as well, a sheet-shaped piezoelectric element made of a piezoelectric ceramics piezoelectric material is used, and a first electrode and a second electrode are provided between each piezoelectric element. It is a piezoelectric conversion element configured by alternately sandwiching and laminating. The structure is similar to that of the second embodiment, except that the electrode material is different and the layers are laminated after the firing process.

The production of the green sheet is the same as that of the first embodiment. Hereinafter, the same members as those of the piezoelectric conversion element according to the second embodiment will be denoted by the same reference numerals, detailed description thereof will be omitted, and different points will be mainly described.

FIG. 15 is a perspective view showing the structure of the piezoelectric conversion element 40 of the third embodiment. In the following description, the laminated body 4 is used.
Sometimes it is 0. First, a sheet-shaped piezoelectric element 11 called a green sheet made of a piezoelectric ceramic-based piezoelectric material is cut into a predetermined size and fired. Next, the first and second electrodes 42 and 43 are formed by applying an electrode material containing aluminum as a main component to both the front and back surfaces of the fired piezoelectric element 11, and a plurality of these sheets are laminated and laminated. The body 40 is formed.

The first electrode 42 and the second electrode of the laminated body 40 are
The exposed end portion of the electrode 43 is cut and processed by a cutting device called a dicer.

Next, the etching process of the cut surface of the laminated body 40 will be described. End face 40 of the cut laminated body
Since a is a finished surface close to a mirror surface and the end portions of the first electrode 42 and the second electrode 43 made of an electrode material containing aluminum as a main component are exposed, PZT which is the material of the piezoelectric element is melted. First, only the first electrode 42 and the second electrode 43 exposed on the end face 40a are selectively etched by an alkaline solution that dissolves only aluminum (Al), for example, an etching solution containing sodium hydroxide (NaOH).

FIG. 16 shows the laminated body 4 before and after etching.
16 is an enlarged cross-sectional view for explaining the state of the end surface of FIG. 0, FIG. 16A shows the state of the end surface before the etching process, and FIG.
(B) shows the state of the end face after etching.

That is, before the laminated body 40 is immersed in the etching solution, the end surface of the piezoelectric element 11 (upper surface in FIG. 16) and the end surfaces of the first electrode 42 and the second electrode 43 (upper surface in FIG. 16) are flush with each other. It is above. When immersed in an etching solution, the first electrode 4
Only the end faces of the second electrode 43 and the second electrode 43 are etched, the piezoelectric element 11 remains without being etched, and an uneven surface is formed in which the end faces of the first electrode 42 and the second electrode 43 are recessed from the end faces of the piezoelectric element 11.

According to this embodiment, since the electrode is formed after firing and the electrode is not affected by heat during firing, a material containing aluminum as a main component can be used as the electrode material.

Further, the electrode material containing aluminum as a main component is etched by the etching process, and the first electrode 4
Since the second and second electrodes 43 are recessed from the end face of the piezoelectric element 11, an insulating layer is provided between the piezoelectric conversion element and the fixing member and the driving member (carbon shaft) as in the first and second embodiments. Need not be provided. That is, it is not necessary to mix glass particles or the like into the adhesive used for the joining process, and the joining can be performed more firmly.

[Fourth Embodiment] The piezoelectric conversion element of the fourth embodiment is similar to the piezoelectric conversion element of the first embodiment in that the surface of a sheet-shaped piezoelectric element made of a piezoelectric ceramics piezoelectric material. Also, the piezoelectric conversion element is formed by forming the first electrode and the second electrode on the back surface, folding the first electrode and the second electrode in two at substantially the central portion, and winding up around the bent portion to form a columnar body.

The structure is similar to that of the first embodiment, but is different in that a sputtering process is performed instead of the etching process of the cut surface of the laminated body in the first embodiment. Hereinafter, the same members as those of the piezoelectric conversion element according to the first embodiment will be denoted by the same reference numerals, detailed description thereof will be omitted, and different points will be mainly described.

FIG. 17 is a perspective view showing the external appearance of the piezoelectric conversion element 50 according to the fourth embodiment. The piezoelectric conversion element 50 is
A sheet-shaped piezoelectric element 11 made of a piezoelectric ceramics-based piezoelectric material, and a first electrode 1 made of a platinum (Pt) -based electrode material.
2 and the second electrode 13 are alternately sandwiched and laminated,
The piezoelectric element is folded in two at the substantially central portion, and is rolled up so that the piezoelectric elements are laminated around the bent portion 14 to form a columnar body. Further, after firing the laminated body 50 at a predetermined temperature, the first
The end portion where the electrode 12 and the second electrode 13 are exposed is cut and processed by a cutting device called a dicer.

In the columnar body (or tubular body, hereinafter, for convenience of description, both of them are referred to as columnar bodies) having this structure, as is apparent from FIG. 17, the first electrode 12 and the first electrode 12 are provided on the outer peripheral surface of the columnar body. The two electrodes 13 are exposed, and the end faces of the first electrode 12 and the second electrode 13 are exposed in a spiral shape on both end faces of the columnar body in the axial direction.

Next, the sputtering process of the electrode exposed on the cut surface of the columnar body (piezoelectric conversion element) 50 will be described. FIG. 18 is a conceptual diagram for explaining the sputtering process of the columnar body 50. The first process electrode 55 is provided inside the vacuum container 58.
And the second machining electrode 56 are arranged, the first electrode 12 and the second electrode 13 exposed on one end face of the columnar body 50 are connected to the first machining electrode 55, and the other end face of the columnar body 50 is connected. The exposed first electrode 12 and second electrode 13 are opposed to the second processed electrode 56.

When the inside of the vacuum container 58 is evacuated and the first machining electrode 55 is connected to the positive electrode of the power source 57 and the second machining electrode 56 is connected to the negative electrode of the power source 57, the first electrode 12 and the second electrode 13 are separated from each other. Platinum (Pt) ions fly out toward the second processed electrode 56, and the first electrode 12 and the second electrode 13 exposed on the other end surface of the columnar body 50 are recessed due to corrosion.

FIG. 19 is an enlarged sectional view for explaining the state of the end face of the columnar body 10 before and after the sputtering process.
9A shows the state of the end face of the columnar body 10 before the sputtering process, and FIG. 19B shows the state of the end face after the sputtering process.

That is, before the end surface of the columnar body 10 is processed by sputtering, the end surface of the piezoelectric element 11 and the end surfaces of the first electrode 12 and the second electrode 13 (the upper surface in FIG. 19) are on the same plane. After the sputtering process, the portions of the first electrode 12 and the second electrode 13 exposed on the end face are the piezoelectric element 1.
The ceramics, which is the first part, is recessed from the end face, and the end face is formed into an uneven surface.

According to this embodiment, the first electrode 12 and the second electrode 13 are formed into the piezoelectric element 1 by sputtering.
Since it is recessed from the end face of No. 1, it is not necessary to provide an insulating layer between the fixing member and the drive shaft (carbon shaft) as in the case of the third embodiment. That is, it is not necessary to mix glass particles or the like into the adhesive used for the joining process, and the joining can be performed more firmly.

[Fifth Embodiment] Like the piezoelectric conversion element of the first embodiment, the piezoelectric conversion element of the fifth embodiment has a surface of a sheet-shaped piezoelectric element made of a piezoelectric ceramics piezoelectric material. A first electrode and a second electrode are formed on the back surface of the piezoelectric conversion element, and the first and second electrodes are formed on the back surface.

In the description of the first embodiment, the columnar body 10
Since the outer peripheral surface of is covered with the first electrode 12 and the second electrode 13 made of a platinum (Pt) -based electrode material, the columnar body 10
It was explained that the outer peripheral surface of No. 1 was not etched by the etching process.

When the outer peripheral surface of the piezoelectric conversion element (columnar body) 10 is completely covered with the electrode material, it is not etched. However, when the electrode material is applied to the front surface and the back surface of the sheet-shaped piezoelectric element by screen printing or another method, as shown in FIG. 20, the piezoelectric element (PZT) is spotted on the outer peripheral surface of the columnar body 10 due to uneven coating. It may be exposed to the shape 11d. In addition, since the end portions 11e and 11f in the winding direction of the sheet-shaped piezoelectric element rolled up in the columnar body are not covered with the electrode material (when covered with the electrode material, the first electrode 12 and the second electrode 13 are short-circuited). Resulting in),
It is unavoidable that the piezoelectric element (ceramics) is exposed at this portion.

Therefore, in the fifth embodiment, the columnar body 1
The outer peripheral surface of No. 0 is further covered, and only the cut surface is etched. Hereinafter, this processing method will be described with reference to FIG.

FIG. 21 is a view for explaining a work fixing base used in the processing method of the fifth embodiment, and FIG.
Is a plan view showing a state where the columnar body is fixed on the fixing base, and FIG. 21B is a sectional view taken along the line AA of the fixing base.

In FIGS. 21A and 21B, 61
Is a work fixing base made of synthetic resin such as Teflon resin (trade name), and 70 is a sheet-shaped piezoelectric element made of a piezoelectric ceramics piezoelectric material, like the columnar body of the first embodiment. A plurality of columnar bodies (piezoelectric conversion elements), which are columnar bodies formed by stacking the first electrode and the second electrode alternately sandwiched between the piezoelectric elements and folding the stack to form a columnar body. Are integrally formed.

A plurality of grooves 62 having a V-shaped cross section for arranging the integrally formed columnar bodies 70 are provided on the fixed base 61, and are orthogonal to the V-shaped grooves 62. A plurality of relief grooves 63 of the cutter of the cutting device (dicer) described in the first embodiment are provided in the direction. The distance between the escape grooves 63 is determined by the lengthwise dimension of each columnar body (piezoelectric conversion element) cut out from the columnar body 70 integrally formed.

A plurality of V-shaped grooves 62 on the fixed base 61
The columnar bodies 70 formed integrally with each of the columnar bodies 70 are lined up, and an adhesive agent 64, for example, a rubber-based adhesive agent is flown from above the columnar body bodies 70 and the V-shaped groove 62 so as to cover the entire columnar body bodies 70.
Is fixed to the fixing base 61 by adhesive, and the columnar body 70 is cut by operating the dicer so that the cutter of the dicer (not shown) moves along the escape groove 63.

When the same etching solution as that described in the first embodiment is prepared, and the cut columnar body 70 is immersed in the etching solution together with the fixing table 61, the outer periphery of the columnar body covered with the adhesive 64. The surface is not etched because it does not contact the etchant. Further, the cut surface of the columnar body 70 cut by the dicer comes into contact with the etching liquid, and only the piezoelectric element 11 exposed on the end surface is etched, so that the end surface of the first electrode 12 and the second electrode 13 is cut off. An uneven surface protruding from the end surface of the is formed.

After the etching process is completed, the fixed base 61 is pulled up from the etching liquid, and the adhesive 64 is dissolved in a suitable solvent, for example, acetone to obtain individual etched columnar bodies (piezoelectric conversion elements) 10. be able to.

According to this embodiment, spot-shaped holes formed when the electrode material is applied to the front surface and the back surface of the sheet-shaped piezoelectric element by screen printing or other methods, and the end portion in the winding direction of the piezoelectric element. Since the portion not covered with the electrode material is also covered with the adhesive, it is not etched even in the etching process. Further, a plurality of columnar bodies (piezoelectric conversion elements) can be cut out from one integrally formed columnar body, and etching processing can be performed, so that work efficiency can be improved.

[Sixth Embodiment] A sixth embodiment is a sheet made of a piezoelectric ceramic-based piezoelectric material, like the piezoelectric conversion elements of the first, fourth and fifth embodiments. Forming a first electrode and a second electrode on the front surface and the back surface of the piezoelectric element, and folding and stacking the first electrode and the second electrode at a bent portion in a substantially central portion so that the piezoelectric elements are laminated with each other around the bent portion. The present invention relates to a piezoelectric conversion element that is rolled up to form a columnar body.

In this structure, the piezoelectric conversion element of the first embodiment shown in FIG. 3 will be described. The bending portion 14 at the substantially central portion is folded in two and laminated, and rolled up to form a columnar body. At this time, the first electrode and the second electrode are exposed on the outer peripheral surface of the columnar body, but the first electrode 12 and the second electrode 1 exposed on the outer peripheral surface.
Both 3 have a metallic color of platinum (Pt), the positions of the end portions of the first electrode and the second electrode are difficult to understand, and the lead wire cannot be easily connected to the electrodes.

Therefore, in the sixth embodiment, as shown in FIGS. 22 and 23, the first electrode 82 and the second electrode 83 are formed on the front surface and the back surface of the sheet-shaped piezoelectric element 11 by means of screen printing or the like. When it is formed, platinum (P
t) An electrode material made of a system electrode material is applied by means such as screen printing, but the end portion of the first electrode 82 in the winding direction (end portion in the winding direction when winding into a columnar body) 82a,
In addition, platinum (Pt) is formed on the end portion in the winding direction of the second electrode 83 (end portion in the winding direction when winding into a columnar body) 83a.
An electrode material obtained by adding cadmium (Cd) to the system electrode material is used.

According to this structure, as shown in FIG.
After being folded in two at the bent portion 14 in the substantially central portion, laminated, rolled up to form a columnar body, and fired, the end portion 82a of the first electrode and the end portion 83a of the second electrode become cadmium (C
The color of d) is discolored, the platinum (Pt) electrode, which is the first electrode 82 and the second electrode 83, can be easily distinguished, and the lead wire can be easily connected to the electrodes.

[0088]

As described in detail above, the invention of claim 1 provides a piezoelectric conversion element comprising a laminated body in which a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material and an electrode body are laminated. The joint surface for adhering and fixing the piezoelectric conversion element to another member is formed on the uneven surface where either the piezoelectric element or the electrode body projects.

According to a ninth aspect of the present invention, the piezoelectric conversion element in the piezoelectric conversion element composed of a laminated body in which a sheet-shaped piezoelectric element composed of a ceramic-based piezoelectric material and an electrode body are laminated is fixed to another member by adhesion. This is a method of processing a joint surface, which selectively corrodes either one of the piezoelectric element and the electrode body exposed on the joint surface to form an uneven surface.

Further, in the invention of claim 10, a piezoelectric conversion element having a concave-convex bonding surface for bonding and fixing to the other member, a fixing member for fixing the piezoelectric conversion element, and a piezoelectric conversion element fixed to the piezoelectric conversion element. In an actuator that uses a piezoelectric conversion element that includes a driving member that is driven by the driving member and a driven member that is driven by the driving member, the piezoelectric conversion element is bonded to the fixing member and the driving member with an adhesive on the bonding surface that is the uneven surface. It is an actuator that is applied and joined.

According to the present invention, the joint surface for adhering and fixing the piezoelectric conversion element to the other member is formed on the uneven surface on which either the piezoelectric element or the electrode body is projected. Thus, the adhesive strength can be sufficiently increased, and even when the piezoelectric conversion element is driven at a high speed for a long time, there is no risk of the bonded surface being peeled off, and the piezoelectric conversion element can be stably driven for a long time.

[Brief description of drawings]

FIG. 1 is a perspective view showing a piezoelectric element that is a material of a piezoelectric conversion element according to a first embodiment.

FIG. 2 is a perspective view of the piezoelectric element shown in FIG. 1 folded in two.

FIG. 3 is a perspective view showing the external appearance of a piezoelectric conversion element in which the piezoelectric element shown in FIG. 1 is formed into a columnar body.

FIG. 4 is a diagram illustrating a step of forming a piezoelectric element into a cylindrical body by using a winding shaft.

FIG. 5 is a diagram illustrating temperature conditions when firing a piezoelectric element.

FIG. 6 is a diagram for explaining a cutting process of both axial end portions of a columnar body (piezoelectric conversion element).

FIG. 7 is a conceptual diagram illustrating etching processing of a columnar body (piezoelectric conversion element).

FIG. 8 is an enlarged cross-sectional view illustrating a state of an end surface of a columnar body before and after etching processing.

FIG. 9 is a sectional view of an actuator using a piezoelectric conversion element.

FIG. 10 is a comparative explanatory view of the adhesive strength between the case where the axial end surface (without electrode) of the piezoelectric conversion element is etched and the case where it is not etched.

FIG. 11 is a comparative explanatory diagram of the adhesive strength between the case where the axial end surface (PZT and the electrodes are exposed) of the piezoelectric conversion element is etched and the case is not etched.

FIG. 12 is a view for explaining the relationship between the etching depth and the adhesive strength.

FIG. 13 is a perspective view showing a configuration of a piezoelectric conversion element according to a second embodiment.

FIG. 14 is an enlarged cross-sectional view illustrating a state of an end surface of a laminated body before and after etching processing.

FIG. 15 is a perspective view showing a configuration of a piezoelectric conversion element according to a third embodiment.

FIG. 16 is an enlarged cross-sectional view illustrating a state of an end surface of a laminated body before and after etching processing.

FIG. 17 is a perspective view showing the external appearance of the piezoelectric conversion element according to the fourth embodiment.

FIG. 18 is a conceptual diagram illustrating an electrode sputtering process.

FIG. 19 is an enlarged cross-sectional view illustrating the state of the end surface of the columnar body before and after the sputtering process.

FIG. 20 is a diagram for explaining a portion of the outer peripheral surface of the columnar body which is not covered with the electrode material and a portion of the end portion in the winding direction of the piezoelectric element which is not covered with the electrode material, which is caused by uneven coating.

FIG. 21 is a diagram illustrating a work fixing base used in the processing method according to the fifth embodiment.

FIG. 22 is a view (No. 1) for explaining the first electrode and the second electrode formed on the piezoelectric element which is the material of the piezoelectric conversion element according to the sixth embodiment.

FIG. 23 is a view (No. 2) for explaining the first electrode and the second electrode formed on the piezoelectric element which is the material of the piezoelectric conversion element according to the sixth embodiment.

FIG. 24 is a perspective view showing the external appearance of the piezoelectric conversion element according to the sixth embodiment.

FIG. 25 is an exploded perspective view illustrating an assembly process of an actuator using a conventional piezoelectric conversion element.

26 is a perspective view of an actuator using the conventional piezoelectric conversion element shown in FIG.

[Explanation of symbols]

10 Piezoelectric conversion element (columnar body) 10a, 10b end faces 11 Piezoelectric element 12 First electrode 13 Second electrode 14 Folding section 19 Etching liquid 20 Activator 21 Fixing member 23 Carbon shaft (drive shaft) 24 Adhesive 25 Drive pulse generation circuit 27 Moving body (driven member) 30 Piezoelectric conversion element (laminated body) 40 Piezoelectric conversion element (laminated body) 42 first electrode 43 Second electrode 50 Piezoelectric conversion element (columnar body) 55 First machining electrode 56 Second machining electrode 57 power 58 Vacuum container 61 Fixed base 62 Groove with V-shaped cross section 63 escape groove 64 adhesive 70 columns

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Shinya             2-3-3 Azuchi-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Osaka International Building Minolta Co., Ltd. F-term (reference) 5H680 AA04 AA12 BB13 CC05 DD01                       DD23 DD27 DD37 DD39 DD53                       DD73 DD83 DD95 FF08 FF12                       FF17 FF32 FF38 GG02 GG20                       GG25

Claims (10)

[Claims] 1. A piezoelectric conversion element composed of a laminated body in which a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material and an electrode body are laminated, wherein a bonding surface for adhering and fixing the piezoelectric conversion element to another member comprises: A piezoelectric conversion element, characterized in that either one of the piezoelectric element and the electrode body is a surface formed on a protruding and recessed surface. 2. The bonding surface is a surface that is formed as a concavo-convex surface by selectively etching one of a piezoelectric element and an electrode body that are both exposed to the bonding surface. The piezoelectric conversion element described. 3. The joint surface is a surface that is formed as an uneven surface where the piezoelectric element is concave and the electrode body is convex by performing a selective etching process in which the piezoelectric element is etched and the electrode body is not etched. The piezoelectric conversion element according to claim 2, wherein 4. The joint surface is a surface formed by an uneven surface where the electrode element is etched and the piezoelectric element is not etched, and the piezoelectric element is convex and the electrode body is concave by selective etching. The piezoelectric conversion element according to claim 2, wherein 5. The joint surface is formed on a concavo-convex surface in which the piezoelectric element and the electrode body, which are both exposed to the joint surface, are selectively sputtered to make the piezoelectric element convex and the electrode body concave. The piezoelectric conversion element according to claim 1, wherein the piezoelectric conversion element is a curved surface. 6. The piezoelectric conversion element is a piezoelectric conversion element formed into a columnar body or a cylindrical body by rolling up a laminated body in which a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material and an electrode body are laminated. The piezoelectric conversion element according to any one of claims 1 to 5. 7. The piezoelectric conversion element is a laminated body in which a sheet-shaped piezoelectric element made of a ceramic-based piezoelectric material and an electrode body are laminated, and a piezoelectric conversion element in which displacement occurs in a direction perpendicular to a voltage application direction. 2. The method according to claim 1, wherein
The piezoelectric conversion element according to claim 5. 8. The piezoelectric conversion element according to claim 1, wherein the concave-convex surface has a thickness (aspect ratio) of the electrode body with respect to a recess depth of 5 or less. 9. A method for processing a bonding surface, wherein a piezoelectric conversion element in a piezoelectric conversion element composed of a laminated body in which a sheet-shaped piezoelectric element composed of a ceramic-based piezoelectric material and an electrode body are laminated is adhered and fixed to another member. A method of processing a piezoelectric conversion element, characterized by selectively corroding either one of the piezoelectric element and the electrode body, which are both exposed on the bonding surface, to form an uneven surface. 10. The piezoelectric conversion element according to claim 1, a fixing member for fixing the piezoelectric conversion element, a driving member fixed to the piezoelectric conversion element, and the driving member. In an actuator using a piezoelectric conversion element having a driven member driven by, the joining of the piezoelectric conversion element, the fixed member and the driving member,
An actuator using a piezoelectric conversion element, wherein an adhesive is applied to a bonding surface, which is an uneven surface formed on the piezoelectric conversion element, and the piezoelectric conversion element is bonded.