JPS63257474A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To lower the cost of the title apparatus by bringing a plurality of piezoelectric vibrators each with a plane-shaped fan and with the back larger than the contact part, into contact with a rotor. CONSTITUTION:A plane, fan-shaped piezoelectric vibrator 1 is constituted in such manner that its top and under-surfaces are provided with electrodes 2, 3 and its back 1a is sufficiently longer than its contact part 1b. When an AC electric field is applied to these electrodes 2, 3, said vibrator 1 vibrates in the direction of thickness and there is generated an external vibration differing by 90 deg. in phase from the first vibration. Then, a progressive wave is generated in the back 1a by the combination of these two vibrations. In an ultrasonic motor, moreover, a rotating shaft 6 is rotatably supported by a bearing 5 mounted in a case 4, and three contact parts 1b of said fan-shaped piezoelectric vibrators 1 makes contact with said rotating shaft 6 via an abrasion resistance member 7 and are pressed by flat springs 8. Thus, the rotating shaft 6 can be turned by a progressive wave generated in said contact parts 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic motor that utilizes traveling waves generated on the side surface of a piezoelectric vibrator, as described in A.

The currently proposed ultrasonic motor has two sets of electrodes glued to one side of an annular piezoelectric ceramic.

The electrodes are arranged so that the standing waves excited by each electrode group are shifted by 90 degrees in position, and the alternating current electric fields applied to these two sets of electrode groups have a temporal phase difference of 90 inches. The oscillators are connected to each.

The conventional ultrasonic motor configured as described above generates two standing waves with a 90' phase shift on the surface around the annular piezoelectric ceramic by applying an alternating electric field from two sets of oscillators to each electrode group. A traveling wave is generated by combining these two standing waves. Therefore, when a toroidal movable body is placed on a nine-comb-shaped vibrating body bonded to one toroidal piezoelectric ceramic and the contact is strengthened, the movable body is moved by a traveling wave.

However, this conventional ultrasonic motor requires multiple electrodes and two sets of oscillators that apply an alternating electric field to these electrodes, making the electrode configuration complicated and causing vibrations. The structure of the body is also complicated, which raises the problem of high cost.

In order to solve the above-mentioned problems, the present invention uses one or more substantially fan-shaped piezoelectric vibrators having a sufficiently small contact portion with respect to the back and having electrodes on both sides. It is characterized in that the plurality of contact parts are brought into contact with the rotating shaft directly or through a wear-resistant member.

According to the present invention, when an alternating electric field is applied to the electrodes of a piezoelectric vibrator whose contact portion is sufficiently small with respect to the back, vibrations in the thickness direction occur in the piezoelectric vibrator, and the vibrations in the thickness direction are An outer shell vibration deviated by 90 degrees occurs. This shell vibration is a vibration in which the sides of the piezoelectric vibrator repeatedly expand and contract evenly, but if the contact part is small enough with respect to the back, the shell vibration causes the sides to expand and contract unevenly, making contact with the back. A traveling wave is generated along the side of the area and its vicinity. When this contact portion is brought into contact with the rotating shaft directly or through a wear-resistant member, the rotating shaft is rotated by the traveling wave and operates as an ultrasonic motor.

First, before a detailed explanation of the present invention, the principle will be explained. First, as shown in FIG. 1(b), in the piezoelectric vibrator 1 in which the back part 1a with the electrodes 2.3 provided on the upper and lower surfaces is sufficiently long with respect to the contact part 1b and has a fan-shaped planar shape, these electrode 2,
When an alternating current electric field is applied to 3, the piezoelectric vibrator l vibrates in the thickness direction, and an outer vibration with a phase difference of 90 degrees with respect to the thickness direction vibration is generated. As shown in FIG. 1(a), as shown in FIG. It has been confirmed that a traveling wave in the opposite direction to arrow A is generated at the contact portion 1b as shown by arrow C, with
Furthermore, it was confirmed that traveling waves were generated as shown by arrows E in the vicinity of the contact portion 1b. It was confirmed that when a rotating body is brought into contact with the part where this traveling wave is generated, the rotating body rotates very strongly.

2 is a plan sectional view of an ultrasonic motor according to an embodiment of the present invention, and FIG. 3 is a side sectional view of the ultrasonic motor shown in FIG. The contact portions 1b of the three sector-shaped piezoelectric vibrators 1 are rotatably supported, and the contact portions 1b of the three fan-shaped piezoelectric vibrators 1 are in contact with the rotating shaft 6 via the wear-resistant member 7.
Further, the piezoelectric vibrators 1 are each pressed in the direction of the rotating shaft 6 by leaf springs 8 provided on the back portions 1a of the piezoelectric vibrators 1, respectively.

In the ultrasonic motor of this embodiment configured in this way, 3
The rotating shaft 6 is rotated by the traveling wave indicated by the arrow C generated at the contact portion 1b of each of the piezoelectric vibrators 1. Therefore,
It has the advantages of a very simple configuration, easy miniaturization, easy manufacture, and low cost.

In the above embodiment, three piezoelectric vibrators 1 are provided, but two or more piezoelectric vibrators 1 may be provided. Furthermore, although the contact portion 1b of the piezoelectric vibrator 1 is brought into contact with the rotating body 6 via the wear-resistant member 7, the contact portion 1b of the piezoelectric vibrator 1 may be brought into direct contact.

FIG. 4 is a sectional view of an ultrasonic motor according to another embodiment of the present invention, in which a bearing 9 is provided in the case 4 opposite to the bearing 5, and a rotating body 6 is rotatably supported by these bearings 5 and 9. are doing. Further, the piezoelectric vibrators 1 are provided in three rows, each piezoelectric vibrator 1 is pressed in the axial direction by a spring 8, and the wear-resistant member 7 is in contact with the rotating shaft 6, respectively. Furthermore, a spacer 10 is inserted between adjacent piezoelectric vibrators 1.

In the ultrasonic motor of this embodiment configured in this way, 3
Each contact portion 1 of each piezoelectric vibrator 1 in the row
Since the rotating shaft 6 is rotated by the traveling wave of arrow C generated at point b, there is an advantage that the torque becomes even stronger.

In addition, in the above embodiment, the rotating body 6 may be supported by a bearing 5, 9, etc., or may be directly supported by a case.
Other bearings etc. may also be used.

As is clear from the above description, the present invention provides a plurality of piezoelectric vibrators whose planar shape is fan-shaped and whose back portions are very large compared to the contact portions. Since it has a simple structure in which it is brought into contact with the rotating body through an abrasive member, it has the advantage of being easy to manufacture and being inexpensive.

[Brief explanation of the drawing]

1 is a plan view and a perspective view of a piezoelectric vibrator having a fan-shaped planar shape for explaining the present invention in detail, FIG. 2 is a plan view of an ultrasonic motor according to an embodiment of the present invention, and FIG. 2 is a side sectional view of the ultrasonic motor shown in FIG. 2, and FIG. 2 is a side sectional view of the ultrasonic motor of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Piezoelectric vibrator, 2.3... Electrode, 4... Case, 5°9... Bearing, 6... Rotating shaft, 7...
・・Wear-resistant parts. 8...Spring, 10 Spacer.

Claims (2)

[Claims] (1) Connect one or more approximately fan-shaped piezoelectric vibrators whose contact portions are sufficiently small with respect to the back and electrodes are provided on both sides, and connect each of the contact portions directly or with a wear-resistant material. An ultrasonic motor characterized in that it is brought into contact with a rotating shaft via a. (2) The ultrasonic motor according to claim 1, wherein the piezoelectric vibrators are arranged in multiple layers.