JPH03155373A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To obtain a highly efficient ultrasonic motor having simple drive circuit by combining a piezoelectric vibrator as a stator, a dielectric or an insulator as a mover, and a resistor and further combining the movement through piezoelectric effect and movement through electrostatic force. CONSTITUTION:A mover 3 and a resistor 2 are constructed integrally, lower face of a piezoelectric vibrator 1 having electrodes A, B on the upper and lower faces is fixed to provide a stator 1 for a motor, and the mover 2 is mounted thereon. The mover 1 is polarized in parallel with the electrodes A, B, and slip is caused through application of + voltage onto the electrode A thus moving the mover 3 to the right. Upon application of - voltage, the vibrator 1 twists in the opposite direction but the vibrator 1 is repelled by -charges on the mover 3 to cause slight floating of the mover thus preventing accompanied motion of the mover 3. By such arrangement, an ultrasonic motor having high efficiency and simple driving circuit can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic motor, and more particularly to an inchworm type actuator.

BACKGROUND OF THE INVENTION In recent years, piezoelectric displacement elements have been actively developed and applied. Piezoelectric elements are attracting attention as actuators for precision positioning because they can relatively easily achieve displacement accuracy on the order of submicrons through voltage control.

By incorporating an electrostrictive element or a magnetostrictive element into one elastic body, the ultrasonic wave excited on the surface is utilized, and the powerful vibrational energy of the ultrasonic wave generates a traveling wave accompanied by elliptical vibration. JP-A-58-148682 proposes a motor device that utilizes surface acoustic waves that are generated and converted into rotational or rectilinear motion of a moving body. However, since the motor device disclosed in the publication uses surface acoustic waves, it requires a high frequency, and the displacement is small.Also, it requires a driving wave with a correct phase difference, which has the disadvantage of high circuit cost. there were.

Also, IEICE Technical Report, US88-6L P, P29-36
(rotating inchworm type actuator), an ultrasonic motor that uses vertical and horizontal movement vibrators to obtain rotational force has been proposed, but this motor uses separate vibrations for vertical and horizontal movement. Since this is done using a vibrator, two vibrator drive circuits are required, and the structure is complicated and large.

Purpose The present invention was made in view of the above-mentioned circumstances.
In particular, this invention aims to provide an ultrasonic motor that is efficient and has a simple drive circuit.

Structure In order to achieve the above object, the present invention includes a piezoelectric vibrator,
It consists of a combination of a dielectric or insulator and a resistor provided between the piezoelectric vibrator and the dielectric or insulator, and the piezoelectric effect is achieved by using the piezoelectric vibrator as a stator and the dielectric or insulator as a mover. It is characterized by a combination of movement due to electrostatic force and movement due to electrostatic force. The following will explain one embodiment of the present invention.

Figure 1 is a configuration diagram for explaining one embodiment of the present invention. In the figure, 1 is a piezoelectric vibrator (stator), 2 is a resistor, and 3 is a mover (dielectric or insulator). , the mover 3 and the resistor 2
is integrally constructed.

As shown in the figure, the lower surface of a piezoelectric vibrator 1 having electrodes A and B on its upper and lower surfaces is fixed to serve as a stator of a motor.

Place the mover on top of it. At this time, the movable element may be brought into contact with the stator by its own weight, or the movable element may be pressed against the stator by a spring or the like.

The polarization direction (F) of the vibrator is parallel to the electrodes, and when a voltage is applied, torsional deformation occurs due to the piezoelectric thickness shear effect.

FIG. 2 is a diagram for explaining the operating principle of the present invention. When a voltage of 10 is applied to the upper surface electrode A, a slip as shown in FIG. 2(a) occurs, and the slider 3 moves to the right. do. When the voltage is maintained at ten, one charge is induced in the moving element 3, which is a dielectric or an insulator, as shown in FIG. 2(b). At this time, since there is a resistor 2 in the middle, there is a time delay before one charge is induced.As shown in FIG. 2(c),
When the voltage of the electrode A is switched to -, the vibrator 1 is twisted in the opposite direction, but one charge on the movable element 3 is repelled and the movable element floats a little, and the movable element 3 does not follow back. next,
As shown in FIG. 2(d).

When the voltage across the oscillator is cut off, the oscillator returns to its original state, and the charge induced in the dielectric material discharges and returns to its original state. By repeating this cycle, the mover moves in an inchworm manner.

FIG. 3 is a diagram showing another embodiment of the present invention. As in this embodiment, the polarization direction of the piezoelectric vibrator 1 may be set downward in the direction perpendicular to the electrodes, and the lateral direction may be fixed. If you do this,
When voltage is applied, it stretches to the right.

Since it contracts when a reverse voltage is applied, it can be sent using this movement.

Note that the above uses the deflection of the vibrator for horizontal movement,
Although a method of using electrostatic repulsion force for vertical vibration has been shown, it is also possible to use a vibrator for vertical movement and use electrostatic attraction force for horizontal movement.

FIG. 4 is a diagram showing an example of such a case,
As shown in FIG. 4(a), a pair of thickness direction displacement vibrators 1
1. Place mover 3 on top of 12. Next, as shown in FIG. 4(b), when ten voltages are applied to one of the vibrators 11, as shown in FIG.
As shown in c), the dielectric of the mover 3 is charged with a negative charge. Next, as shown in FIG. The adjacent vibrator stretches, and the movable element moves due to electrostatic attraction. The dielectric material is preferably a polymeric material such as electret or PVDF, but may also be an inorganic material.

As is clear from the above explanation, according to the present invention, by dividing vertical and horizontal movement into electrostatic force and piezoelectric force, only one drive circuit is required for the piezoelectric vibrator, resulting in low cost. Become. Furthermore, by dividing the movement, the movement can be made faster and the movement can be carried out more reliably.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram for explaining one embodiment of the present invention,
Fig. 2 is a diagram for explaining the operating principle of Fig. 1;
4 and 4 are configuration diagrams for explaining embodiments in addition to the present invention, respectively. 1.11,12...Piezoelectric vibrator, 2...Resistor, 3
...Mover (dielectric or insulator).

Claims (1)

[Claims] 1. Consisting of a combination of a piezoelectric vibrator, a dielectric or insulator, and a resistor provided between the piezoelectric vibrator and the dielectric or insulator, the piezoelectric vibrator is connected to a stator, the dielectric or insulator An ultrasonic motor characterized by combining movement by piezoelectric effect and movement by electrostatic force using a body as a mover.