JPH06153542A - Stator of ultrasonic motor - Google Patents

Abstract

PURPOSE:To provide a stator of an ultrasonic motor in which an electrode surely conducts with a block body even if the electrode connected to a piezoelectric ceramics is bonded to the metallic block body under a low pressurizing force. CONSTITUTION:In a stator of an ultrasonic motor, while a metal thin film 22 is formed on the surface of a silver electrode 14 polarized and connected to the surface of a piezoelectric ceramics 12, a surface roughness Rz of a connecting surface 16a of the side of the piezoelectric ceramics 12 of a metallic block body 16 is surfaced to a roughness of 2.0 to 10.0mum, and the metal thin film 22 is bonded to the metallic block body 16 through an adhesive 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator of an ultrasonic motor, and more particularly to a stator of an ultrasonic motor formed by connecting an electrode bonded to the surface of piezoelectric ceramics and a metallic block body. Is.

[0002]

2. Description of the Related Art Conventionally, in a stator of an ultrasonic motor, for example, a piezoelectric ceramic is vapor-deposited with a conductor such as silver to provide an electrode, and the electrode and the metallic block body are bonded together by an adhesive or the like. Things are known. In this case, it is necessary to electrically connect the electrode and the block body, and the conventional bonding method is to make the adhesive layer such as an adhesive as thin as possible and add the piezoelectric ceramic electrode and the metallic block body. This is performed by a so-called metal touch in which the electrodes and the block body are partially and accidentally conducted by forming a joint surface by pressure-bonding.

However, in the stator obtained by the above method, the electrodes and the block body are partially and accidentally conducted, so that the conduction points do not uniformly exist on the joint surface. For this reason, sufficient reliability cannot be obtained for an ultrasonic motor having a polarized electrode portion and each electrode portion having to be electrically connected to the block body. Further, it is possible to increase the pressing force in order to uniformly obtain the conduction points with respect to the coupling surface, but there is a problem that the piezoelectric ceramic is broken by the pressing force.

[0004]

SUMMARY OF THE INVENTION Therefore, according to the present invention, when the piezoelectric ceramics and the metallic block body are joined,
An object of the present invention is to provide a stator of an ultrasonic motor in which all the polarized electrode portions and the block body are surely brought into conduction even if they are coupled with a low pressure.

[0005]

In order to solve the above problems, the present invention is directed to a piezoelectric ceramic, an electrode composed of a plurality of electrode portions bonded to the surface of the piezoelectric ceramic and polarized to two or more poles, and a metallic material. In a stator of an ultrasonic motor having the block body and the electrode side and the block body side coupled to each other, a conductive layer made of a conductive material for electrically connecting the polarized electrode portions to each other on the surface of the electrode. And the surface of the metallic block body facing the electrode is processed to have a roughness of 2.0 [μm] or more and 10.0 [μm] or less, and the conductive layer is provided with the metallic block body. And the conductive layer is electrically connected to the block body.

[0006]

According to the present invention, a conductive layer made of a conductive material is provided on the surface of an electrode portion which is provided on the piezoelectric ceramic and which is polarized to have two or more poles, so that the polarized electrode portions become common electrodes and are electrically connected to each other. It will be possible. on the other hand,
The bonding surface of the metallic block body is 2.0 [μm] or more 1
By setting the roughness to be 0.0 [μm] or less, a so-called wedge effect is produced in which, when the conductive layer and the block body are bonded together, the convex and concave portions present on the joint surface of the block body make it difficult for the adhesive to enter.

Therefore, even if the conductive layer and the block body are bonded to each other with a low pressure, the conductive point can be surely obtained with respect to the bonding surface of the conductive layer by the metal touch of the convex portion of the bonding surface. The conducting layer ensures electrical conduction to all the polarized electrode parts. Further, because of the wedge effect, bonding can be performed with a low pressure, so that cracking of the piezoelectric ceramics can be prevented.

[0008]

With the above-mentioned structure, the electric conduction is reliably performed by the metal touch between the electrode provided on the piezoelectric ceramics and the metallic block body, so that the ultrasonic motor is efficiently driven. Can be made.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the stator of the ultrasonic motor of the present invention will be described with reference to the drawings.

1 and 2 show an embodiment of a stator of an ultrasonic motor according to the present invention, FIG. 1 is a sectional view of the ultrasonic motor, and FIG. 2 is a sectional view of essential parts of the stator.

In the embodiment of the present invention, as shown in FIG. 1, a stator 10 of an ultrasonic motor has a ring-shaped piezoelectric ceramic 12 and a silver electrode formed on the surface of the piezoelectric ceramic 12 by vapor deposition. 14 and a metallic block body 16 that transmits the vibration generated from the piezoelectric ceramics 12 to the rotor 18. The rotor 18 has a contact surface 1 on the rotor 18 side of the block body 16.
6b is in pressure contact with a slider 17 via a slider 17, and rotates together with a shaft 20 provided coaxially with a rotor 18 and rotatably supported by a bearing 19. The silver electrode 14 is composed of electrode portions polarized in two or more poles with respect to the circumferential direction of the piezoelectric ceramics 12. By applying a high frequency voltage to each of the polarized electrode portions, the contact of the block body 16 is made. A bending vibration that advances in one direction is generated on the surface 16b. The bending vibration generated on the contact surface 16b causes the rotor 18 to rotate together with the slider 17 in a direction opposite to the traveling direction of the bending vibration.

Next, a method of assembling the silver electrode 14 provided on the piezoelectric ceramics and the metallic block body 16 when assembling the stator 10 of this embodiment will be described.

As shown in FIG. 2, the piezoelectric ceramics 12
Electrode 1 consisting of electrode parts polarized and bonded to the surface of
A metal thin film 22 made of, for example, gold or copper is previously formed on the side of No. 4 which is not joined to the piezoelectric ceramics 12 by sputtering.
As a common electrode of all the polarized electrode portions forming 4, the respective electrode portions are electrically connected.

The present inventor has also found that the metallic block body 1
The following experiment was conducted on the bonding surface of 6 facing the electrode 14 side.

In this experiment, a so-called lapping process was carried out in which the bonding surface of the metallic block body 16 facing the electrode 14 side was polished with an alumina abrasive to roughen the bonding surface and to bond the bonding surface. This is a measurement of the amplitude limit of the piezoelectric ceramic with respect to the surface roughness. That is, a constant voltage was applied to the electrode 14 of the ultrasonic motor, and the crack limit due to the bending of the piezoelectric ceramic when vibration occurred in the piezoelectric ceramic was measured. And
The result is shown in FIG.

As is apparent from FIG. 3, the block body 16
Roughness of bonding surface is 2.0 [μm] or more 10.0 [μm]
Within the following range, the amplitude limit of the piezoelectric ceramic with respect to the roughness of the bonding surface is a particularly high value. Therefore, the coupling surface of the block body 16 is 2.0 [μ
The ultrasonic motor can be efficiently driven by processing the surface to a roughness of m] or more and 10.0 [μm] or less.

In the present embodiment, based on the above experimental results, the coupling surface 16a of the block body 16 on the piezoelectric ceramics 12 side is preliminarily lapped so that the surface roughness Rz is Rz = 4.0.
It is processed to [μm] and countless irregularities are formed on the coupling surface 16a. In this embodiment, the connecting surface 16
The surface roughness of a was measured by the stylus method.

Further, the metal thin film 22 generated by sputtering and the surface roughness Rz are Rz = 4.0 [μ
[m]] bonding surface 1 of the block body 16 lapped
6a and 6a are pressure-bonded to each other via an epoxy adhesive 24, and a part or all of the plurality of convex portions formed on the coupling surface 16a come into contact with the metal thin film 22 by a metal touch. Therefore, even when the conduction points between the metal thin film 22 and the coupling surface 16a do not uniformly exist with respect to the coupling surface 16a, all the polarized electrode portions forming the silver electrode 14 are electrically connected to each other by the metal thin film 22. Therefore, the block body 16 and all the polarized electrode portions are surely conducted. That is, when the piezoelectric ceramics 12 and the block body 16 are bonded together, even if they are bonded with a low pressure, all the polarized electrode portions forming the silver electrode 14 and the block body 16 can be surely conducted.

In the above embodiment of the stator of the ultrasonic motor of the present invention, the joint surface 1 of the block body 16 is used.
Although the surface roughness Rz of 6a was lapped to Rz = 4.0 [μm], it is not limited to this, and as another example, Rz = 7.1 [μm], Rz = 2.
If it is within the range of 0 [μm] to 10.0 [μm], as in the case described above, all the polarized electrode portions of the silver electrode 14 and the block body 16 are joined even if they are joined with a low pressure.
And can be surely conducted.

[Brief description of drawings]

FIG. 1 is an elevation view of an ultrasonic motor according to an embodiment of a stator of an ultrasonic motor of the present invention, showing a right half in a cross section.

FIG. 2 is a sectional view of an essential part of the stator according to the embodiment of the present invention.

FIG. 3 is a graph showing the basis of the present invention, and is a graph showing the relationship between the surface roughness of the bonding surface of the block body and the amplitude limit of the piezoelectric ceramics with respect to the roughness of the bonding surface.

[Explanation of symbols]

 10 Stator 12 Piezoelectric Ceramics 14 Electrode 16 Metal Block 22 Conductive Layer

Claims (1)

[Claims] 1. A piezoelectric ceramic, an electrode composed of a plurality of electrode portions which are joined to the surface of the piezoelectric ceramic and are polarized to have two or more poles, and a metallic block body, the electrode side and the block body side. In a stator of an ultrasonic motor, which is formed by combining the following, a conductive layer made of a conductive material for electrically connecting the polarized electrode portions to each other is provided on the surface of the electrode, and the electrode is opposed to the electrode of the metallic block body. The surface to do is 2.0
A surface is processed to have a roughness of [μm] or more and 10.0 [μm] or less, and the metallic block body is bonded to the conductive layer;
A stator of an ultrasonic motor, wherein the block body and the conductive layer are electrically connected.