JPH02151282A - ultrasonic motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an ultrasonic motor, and particularly to an ultrasonic motor that operates as a uniaxial actuator by applying an electrical signal in the ultrasonic range to a piezoelectric element. be.

[Conventional technology]

Conventionally, as this type of ultrasonic motor, there is one devised by this inventor (Utility Application No. 61-161013), which is explained with reference to Fig. 8. Two drivers (12a) and (12b) are provided protruding from the negative side of the base (11). The base body (11) also has two piezoelectric elements (13a) and (13b) for bending mode, a drive element (12a),
A piezoelectric element (14) is provided on each side surface of (12b). (15) are mounting holes, (A1), (A2)
, (B1), (B2), and (B) are terminals of connection leads of each piezoelectric element, and (FB) is a feedback terminal.

With the above configuration, the voltage in the ultrasonic range can be connected to the terminal (AI).
and (B), the base body (11) and the driver (1
2a) and (12b) are bent as shown by the - dotted chain line, and the driver (12a) kicks out the slider pressed against the driver in the direction of the arrow (M). Furthermore, when a voltage e is applied to the terminals (A 1 ) and (B), the terminals bend as shown by the broken line, and the driver (12b) moves the slider in the direction indicated by the arrow (M).
Kick out in the direction of.

When the above voltage is applied to the terminals (A2) and (B), the polarization of the piezoelectric elements (13a) and (13b) is opposite, so the operation is reversed, and the slider moves in the direction of the arrow (N). driven to.

In this way, the slider, which is the driven body, can be arbitrarily given linear movement in opposite directions.

[Problem to be solved by the invention]

Conventional ultrasonic motors such as those described above require a piezoelectric element to be provided in the drive element as well, which increases the height dimension and makes it difficult to make the motor thinner.
There were problems such as complicated manufacturing work.

This invention aims to solve the above problems, and aims to provide an ultrasonic motor that can be made extremely thin and compact, and that can simplify manufacturing operations. It is something.

[Means to solve the problem]

The ultrasonic motor according to the present invention includes a base made of an elastic rectangular plate having a through hole formed in the center thereof through which the object to be moved is engaged.
A plurality of piezoelectric elements to which electrical signals in the ultrasonic range are applied are fixed, and a composite resonance of a bending mode in the thickness direction and an expansion/contraction mode in the length direction is caused in the base body.

[Function] In this invention, the object to be moved is repeatedly pressed against and released from the inner wall of the through hole in response to vibrations in the longitudinal mode of the base, and vibrates in the axial direction due to vibrations in the bending mode. As a result, the object to be moved is moved in a straight line.

〔Example〕

1 to 4 show an embodiment of the present invention, and FIG.
In FIG. 2, a rectangular through hole (la) is formed in the center of a base body (1) made of a rectangular plate-shaped elastic body. On both sides of the base (1), with a through hole (1a) in between,
Square plate-shaped piezoelectric elements (3a) (3) polarized to the same polarity as each other
b), (11a) and (4b) are fixed respectively.

A rectangular rod-shaped slider (2), which is a moving object, is penetratingly engaged with the through hole (1a) of the base (1).

This slider (2) has a through hole (
Sliding friction members (2a) (2b) are placed in pressure contact with 1a).
between which a spring member (2c) made of hard rubber is provided to constantly generate a pressure contact force.

Note that the electrodes and connection leads provided on the piezoelectric element are omitted from illustration to avoid complexity.

Next, the operation will be explained. The base (1) includes a piezoelectric element (
By using 3a) (3b) or (4a) (4b), the thickness direction bending mode and the length direction stretching mode of bimorph behavior can be generated simultaneously.

In this embodiment, piezoelectric elements (3a) (3b) or (
4a) When the ultrasonic electrical signal is applied to (4b), the fourth
As shown in the figure, the base body (1) is formed in a dimensional relationship that causes a complex resonance of a tertiary bending mode in the thickness direction (a) and a first mode of stretching and contraction in the length direction (b). Due to this movement of the base body (1), the slider (2) is repeatedly pressed against and released from the opposing inner wall of the through hole (1a) due to the longitudinal mode, and is moved up and down in the axial direction due to the bending mode. will be dumped.

Now, when an electric signal is applied to the piezoelectric elements (3a) (3b) and the slider (2) is clamped, if the through hole (1a) in FIG. 2 is swung upward, the slider (
2) moves upward in the same figure.

Then, in the next half cycle, the clamp on the slider (2) is released and at the same time the inner periphery of the through hole (1a) is swung downward, and the slider (2) is released and left in that position. It will be done. Furthermore, in the next half cycle, the clamping and upward movement of the slider (2) are repeated at the period of the applied signal in the same way as before, so the slider (2) ends up moving upward rapidly.

On the other hand, in order to move the slider (2) downward, the signal application may be switched to the piezoelectric elements (4a) and (4b).

That is, piezoelectric elements (3a) (3b) and (4a) (4b
) are polarized to the same polarity, the phase of the longitudinal mode remains the same, and only the phase of the bending mode is reversed, so that reversal of the moving direction of the slider (2) is achieved.

As described above, the direction of movement of the slider (2) is determined by the piezoelectric element (
Since the power supply switching between 3a) (3b) and (4a) (4b) is sufficient, the drive circuit is extremely simplified, and the operation of the self-help circuit that detects the resonant impedance and oscillates is also simplified, making the design easier. becomes easier.

The structure of the slider (2) is that the through hole (la) of the base (1)
It is desirable to always be in pressure contact with the opposing inner walls with a constant force, and various structures for this purpose are conceivable. The shape of the through hole may be square or round.

In addition, in order to further increase the thrust generated in the slider (2), the side surface (to) (B) of the base body (1) shown in FIG.
If a piezoelectric element of the same phase is fixed to the shaft and driven in parallel when moving in both the up and down directions, the expansion/contraction mode in the length direction can be promoted, contributing to an increase in thrust force.

5 to 7 show other embodiments in which the longitudinal stretching mode is the same as that in FIG. 1, but the bending mode is changed to the seventh embodiment.
As shown in the figure (c), the first bending mode is in the width direction, and the reference numerals of each part are the same as in the previous embodiment. The slider (2) shown in Fig. 3 is also used.

Note that the slider (2) generates thrust due to friction with the inner wall of the through hole (la), so the surface is likely to wear out, and therefore the number of times it is used becomes a problem. When applied, it can facilitate movement and prevent wear and tear.

Further, by embedding an encoder means inside the slider (2), it is possible to perform compact and highly accurate position control.

Furthermore, when assembling and fixing the base body, select a location close to the center and near the bending mode node, and tighten and fix the base body via a rubber-like damper material, thereby reducing vibration loss.

It is also conceivable that the base body be composed only of piezoelectric elements.

[Effects of the Invention] As is clear from the above description, the present invention has a rectangular plate-shaped base having a through hole in the center where a moving object engages, and a plurality of piezoelectric elements for driving are provided on both sides of the base. It fixes and excites the base,
Since the object to be moved is moved in a straight line by the combined resonance of the bending mode and the longitudinal mode, the moving direction of the object can be changed simply by switching the power supply to the piezoelectric element, resulting in thinner and more compact designs. Improved workability can be achieved.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention, FIG. 1 is a plan view, FIG. 2 is a side sectional view, FIG. 3 is a partial sectional view, and FIG. 4 is a line showing the operation. It is a diagram. 5 to 7 show other embodiments, FIG. 5 is a plan view,
FIG. 6 is a side sectional view, and FIG. 7 is a diagram showing the operation. FIG. 8 is a side view of a conventional ultrasonic motor. (1)...Base, (1a)...Through hole, (2)...
・Slider (moved object), (3a) (3b), (4a)
(4b)...Piezoelectric element.

Claims (1)

[Claims] A base made of an elastic rectangular plate having a through hole formed in the center thereof through which a rod-shaped object to be moved is engaged, and a plurality of piezoelectric elements fixed to the base and to which electrical signals in the ultrasonic range are applied. An ultrasonic motor that generates complex resonance of a bending mode in the thickness direction and an expansion/contraction mode in the length direction in the base body.