JP2000295877A - Ultrasonic motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high torque, and to smoothly change over left-right rotation. SOLUTION: An electromechanical conversion element 4 in which a proper electrode is formed for bending and vibrating a vibrating body 3 is joined with one surface or both surfaces of an annular vibrating body 3, and driving pieces 5a-5h are mounted on the other surface when the conversion element 4 is joined with one surface and at the proper positions of electrode surfaces when the conversion elements are joined on both surfaces. The vibrating body 3 is supported by fitting supporters 6 inside the driving body 3, voltage with a specified frequency is applied to each electrode formed to the electromechanical conversion elements 4, the vibrating body 3 is bent and vibrated, and driving force is obtained by moving a moving body 7 pressed and contacted to the driving pieces 5a-5h.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic motor which uses an electromechanical transducer such as a piezoelectric element or an electrostrictive element to generate a driving force by the electromechanical transducer.
In particular, the present invention relates to a standing wave type ultrasonic motor utilizing bending vibration.

[0002]

2. Description of the Related Art Conventionally, a piezoelectric element having a plurality of electrodes divided on one surface of a disk-shaped or annular vibrating body made of an elastic body such as metal to excite the vibrating body in bending vibration. And apply a frequency voltage to the electrodes to excite the bending vibration of the vibrating body, and convert the bending vibration into a rotational motion through the protrusion provided on the other surface of the vibrating body, and pressurize the protrusion. BACKGROUND ART A standing wave type ultrasonic motor that frictionally drives a contacted moving body to obtain a driving force is known. This type of ultrasonic motor is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2-287281.
As disclosed in Japanese Patent Laid-Open Publication No. H10-207, a piezoelectric element or an electrostrictive element is bonded to one surface of a disk-shaped vibrating body, and the piezoelectric element is appropriately adjusted so that the vibrating body generates a uniform standing wave. By splitting or forming an electrode pattern, providing a projection on the other surface of the vibrating body at every other position between the antinode and the node of the standing wave, and applying a frequency voltage to the piezoelectric element or the electrostrictive element A flexural standing wave is generated on the vibrating body, and the moving body brought into pressure contact with the protrusion is frictionally driven. It is also stated that the switching direction of the moving body can be switched because the positional relationship between the antinode of the standing wave and the node is shifted by 90 ° in phase by switching the piezoelectric element or the electrostrictive element to which the frequency voltage is applied.

[0003]

Means for attaching the ultrasonic motor to the base is one of the important issues. Because the whole vibrating body is vibrating,
This is because they must be supported or fixed so as not to hinder the vibration. Therefore, in order to efficiently and stably extract the vibration of the vibrating body, it is common for an ultrasonic motor to support or fix a node of vibration of the vibrating body that does not significantly affect the vibration. For example, in the case of a disk-shaped ultrasonic motor, the center of the vibrator, the outer peripheral side surface or the inner peripheral side surface of the vibration node is supported or fixed. However, it does not mean that it does not affect the vibration of the vibrating body at all even if it is supported or fixed by the above means,
Vibration is hindered to a considerable extent. As a result, there is a problem in that the performance of the motor is deteriorated, and a difference in performance in each rotation direction between left and right rotations is caused.

An ultrasonic motor utilizing a bending vibration of a vibrating body is generally divided on one surface of a vibrating body made of an elastic body such as a metal in order to excite the vibrating body to a bending vibration. By joining a piezoelectric element having a plurality of electrodes and applying a frequency voltage to the electrodes, the vibrating body is excited by bending vibration, and is applied to the protrusion via a protrusion provided on the other surface of the vibrating body. The moving body brought into pressure contact is driven by friction. However, in the conventional ultrasonic motor, a piezoelectric element serving as a vibration source can be joined to only one surface of a vibrating body, and a projection for generating a driving force can be provided only on one surface. The torque is limited to several kgf · cm. As a result, when a larger torque is required, it is necessary to provide a transmission mechanism, and there is a problem that the mechanism must be complicated.

It is an object of the present invention to provide an ultrasonic motor which can solve the above-mentioned problems.

[0006]

The ultrasonic motor according to the present invention for solving the above-mentioned problems is characterized in that an annular vibrator having irregularities on the inner peripheral surface is joined to one surface of the vibrator. An electromechanical transducer comprising an annular piezoelectric element or an electrostrictive element, a plurality of electrodes provided on the electromechanical transducer for bending and vibrating the vibrating body, and on the other surface of the vibrating body. A plurality of drivers provided between antinodes and nodes of the bending vibration; a support having irregularities on an outer peripheral surface fitted to irregularities on an inner peripheral surface of the vibrating body; The point is that the moving body is brought into pressure contact.

In addition, an annular vibrating body having irregularities on the inner peripheral surface, an electromechanical transducer comprising an annular piezoelectric element or an electrostrictive element joined to both sides of the vibrating body, and bending the vibrating body A plurality of electrodes provided on the electromechanical transducer to vibrate; a plurality of drivers provided on the electrode surface between antinodes and nodes of the bending vibration; The point is that it is composed of a support body having irregularities on the outer peripheral surface fitted to the irregularities on the peripheral surface, and a moving body brought into pressure contact with the driver.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram of a first embodiment of an ultrasonic motor according to the present invention, wherein FIG.
(B) is a sectional view, and (c) is a bottom view. In the present embodiment, the ultrasonic motor 1 includes an annular vibrator 3 having an uneven inner peripheral surface made of a conductive elastic material such as an aluminum alloy, stainless steel, brass, and iron; It has a unimorph structure in which an annular electromechanical transducer 4 made of a piezoelectric element or an electrostrictive element is joined by known means such as bonding. By joining the vibrating body 3 and the electromechanical transducer 4, the electromechanical transducer 4 that expands and contracts in the radial direction by itself is converted into bending vibration in which the vibrator 3 and the electromechanical transducer 4 are integrated. I have.

In order to cause the vibrating body 3 to bend and vibrate, it is necessary to provide a plurality of electrodes in the circumferential direction of the electromechanical transducer 4, and to enable rotation in both the left and right directions, a multiple of 4 (4, 8). , 12...) May be provided. In the present embodiment, as shown in FIG. 1 (c), the electrodes a1, a2, a3, a4, b of the electromechanical transducer 4 are divided into 16 in the circumferential direction.
1, b2, b3, b4, c1, c2, c3, c4, d
1, d2, d3, and d4 are formed and connected by lead wires A, B, C, and D as shown in FIG.

The electrodes divided into 16 parts in the circumferential direction of the electromechanical transducer 4 are a1, a2, a3, a4, c
1, c2, c3, and c4 are the main vibration electrodes, and b1, b
2, b3, b4, d1, d2, d3, and d4 are used as switching electrodes, and the area of the main vibration electrode is larger than that of the switching electrode.

In this embodiment, as shown in FIG. 1, the switching electrode b formed on the electromechanical transducer 4 is formed on the other surface of the vibrator 3 on which the electromechanical transducer 4 is joined.
1, b2, b3, b4, d1, d2, d3, d4, the driver 5a, 5b, 5c, 5d,
e, 5f, 5g and 5h are provided. As a result, each driver is located between the antinode of the bending vibration of the vibrating body 3 and the node. Note that the driver may be integrated with the vibrator 3 or may be formed by joining another member.

The electromechanical transducer 4 is polarized in the thickness direction and in the same direction. A predetermined frequency voltage is applied to the leads A and B in the same phase, and the frequency voltage is applied to the leads C and D in the opposite direction. Apply simultaneously in phase. That is, the electrodes a1 and b
1, a2 and b2, a3 and b3, a4 and b4, the predetermined frequency voltage is applied to the electrodes in the same phase, and electrodes c1 and d1, c2 and d2, c3 and d3, and c4 and d4. By simultaneously applying the above-mentioned frequency voltages in opposite phases to the electrodes combined with each other, the vibrating body 3 is moved as shown in FIGS.
The bending vibrations are alternately performed with the nodes as vibration nodes.
As a result, each driver provided on one surface of the vibrating body 3 is slightly displaced, and in the case of FIG.
c, 5e and 5g, and in the case of FIG.
In steps b, 5d, 5f, and 5h, a moving body (not shown) that has been brought into pressure contact with each driver is moved rightward on the paper.

In the same manner as described above, a predetermined frequency voltage is applied to the leads A and D in the same phase, and the frequency voltage is applied simultaneously to the leads B and C in the opposite phase. That is, the electrode a1
And d4, a2 and d1, a3 and d2, a4 and d3, and the predetermined frequency voltage in the same phase, electrodes b1 and c1, b2 and c2, b3 and c3, b4 and c.
By simultaneously applying the frequency voltages in opposite phases to the combined electrodes as shown in FIG.
As in (b), bending vibrations are performed alternately with the vibration nodes. As a result, each driver provided on one surface of the vibrating body 3 is slightly displaced, and in the case of FIG.
b, 5d, 5f, 5h, and in the case of FIG. 5 (b), the moving bodies (not shown) pressed against the respective driving elements by the driving elements 5a, 5c, 5e, 5g are moved in the left direction on the paper. Move.

In this embodiment, as shown in FIG. 1, a disk-shaped or ring-shaped support body made of metal or plastic on the inner peripheral surface of the annular vibrating body 3 and having irregularities on the outer peripheral surface. 6, the vibrating body 3 is supported by the support body 6,
The support 6 is fixed to a base 8 (not shown). In the present embodiment, the fitting portion between the vibrating body 3 and the support body 6 is a simple circle having only one unevenness. However, in order to increase the contact area, a gear shape is used instead of a circle. Spline type and serration type are more preferable.

FIG. 6 shows a second embodiment of the ultrasonic motor according to the present invention.
It is a figure of an Example, (A) is a top view and (B) is a sectional view. In the present embodiment, the vibrating body 2 of the ultrasonic motor has an annular vibrating body 3 made of a conductive elastic body such as aluminum alloy, stainless steel, brass, and iron and having an inner surface having irregularities. It has a bimorph structure in which the annular electromechanical transducers 4 are joined by known means such as adhesion.

As in the first embodiment, the two electromechanical transducers 4 bonded to both surfaces of the vibrating body 3 have one in the circumferential direction.
Six divided electrodes a1, a2, a3, a4, b1, b2, b
3, b4, c1, c2, c3, c4, d1, d2, d
3, d4 are formed, and the positional relationship between the electrodes is symmetrical.

Electrodes b1, b2, b3, b formed on two electromechanical transducers 4 joined to both surfaces of vibrator 3
On the planes of 4, d1, d2, d3 and d4, FIG.
, The drivers 5a, 5b, 5c, 5d, 5e, 5
f, 5g and 5h are joined by known means such as adhesion. In addition, as a means for providing a driver on both sides of the vibrating body and generating a driving force from both sides of the vibrating body, a means for joining two vibrating bodies to both sides of the electromechanical transducer is conceivable.
It is not very preferable in terms of manufacturing cost or insulating property.

A wiring pattern of the vibrating body 2 of the ultrasonic motor;
The operating method and principle, the state of vibration of the vibrating body 3, the supporting method, and the like are the same as those in the first embodiment, and detailed description thereof will be omitted.

[0019]

According to the present invention, as described above, the support is fitted to the inside of the ring-shaped vibrator having irregularities on the inner peripheral surface.
By adopting a configuration in which the support is fixed, it is possible to obtain an efficient and stable driving force without obstructing the vibration of the vibrating body. In addition, since the vibrating body can freely vibrate, when switching between left and right rotations, the positions of antinodes and nodes of vibration become clear, rotation can be switched smoothly, and the difference in performance between left and right rotations is reduced. It is possible to do.

Further, by providing a bimorph structure in which the electromechanical transducer is joined to both surfaces of the vibrating body and providing a driver on a predetermined electrode surface formed on the electromechanical transducer,
Conventionally, a driving force generated only from one surface of the vibrating body can be generated from both surfaces of the vibrating body. As a result, it is possible to obtain an ultrasonic motor having a higher torque than the conventional ultrasonic motor.

[Brief description of the drawings]

FIG. 1 is (a) a plan view, (b) a sectional view, and (c) a bottom view of a first embodiment of an ultrasonic motor according to the present invention.

FIG. 2 is a diagram showing a wiring pattern according to the first embodiment of the present invention.

FIG. 3 is a plan view showing nodes of vibration of the vibrating body in the first embodiment of the present invention.

FIG. 4 is a state diagram of vibration of the vibrating body when the moving body is moved rightward in the first embodiment of the present invention.

FIG. 5 is a state diagram of the vibration of the vibrating body when the moving body is moved leftward in the first embodiment of the present invention.

FIG. 6 is (a) a plan view and (b) a cross-sectional view of a second embodiment of the ultrasonic motor of the present invention.

FIG. 7 is a cross-sectional view illustrating an example of a form of an ultrasonic motor according to the present invention.

FIG. 8 is a cross-sectional view showing an example of an embodiment of an ultrasonic motor according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Unimorph type ultrasonic motor 2 Bimorph type ultrasonic motor 3 Vibration body 4 Electromechanical conversion element 5a-5h Driver 6 Support body 7 Moving body 8 Base 9 Case 10 Bearing a1-a4 Main vibration electrode b1-b4 For switching Electrodes c1 to c4 Main vibrating electrodes d1 to d4 Switching electrodes A to D Lead wires Vibration nodes of the vibrating body when moving the moving body to the right direction Vibrating body vibration when moving the moving body to the left direction section

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Shuto Miyashita 13 Hikida, Akiruno-shi, Tokyo F-term in Seratek Co., Ltd. (reference) 5H680 AA06 AA08 BB01 BB16 BB19 CC02 CC06 DD01 DD15 DD23 DD24 DD35 DD39 DD53 DD66 DD85 DD87 DD92 EE03 EE07 EE10 FF32 FF36 GG24 GG25 GG27

Claims (2)

[Claims] 1. An annular vibrating body having irregularities on an inner peripheral surface, an electromechanical conversion element comprising an annular piezoelectric element or an electrostrictive element joined to one surface of the vibrating body, and the vibrating body A plurality of electrodes provided on the electromechanical transducer for bending vibration, and a plurality of drivers provided on the other surface of the vibrating body and provided between antinodes and nodes of the bending vibration. An ultrasonic motor comprising a support having irregularities on an outer peripheral surface fitted into irregularities on an inner peripheral surface of the vibrating body, and a moving body brought into pressure contact with the driver. 2. An annular vibrating body having irregularities on its inner peripheral surface, an electromechanical transducer comprising an annular piezoelectric element or an electrostrictive element joined to both sides of the vibrating body, and bending the vibrating body. A plurality of electrodes provided on the electromechanical transducer to vibrate; a plurality of drivers provided on the electrode surface between antinodes and nodes of the bending vibration; An ultrasonic motor comprising a support having an irregular surface on the outer peripheral surface fitted to the irregularities on the peripheral surface, and a moving body brought into pressure contact with the driver.