JPS60217415A - Actuator - Google Patents

Abstract

PURPOSE:To attain positioning with high accuracy and a long stroke with one actuator by allowing an ultrasonic wave drive motor to move coarsely a mobile body and moving it minutely by means of the movement by inch worm operation. CONSTITUTION:Clamping is released by applying an electric field to a distortion element 41 and an electric field is applied to a distortion element 51, then the distortion element 41 is moved toward right through the contraction of the distortion element 51. Then the electric field of the distortion element 41 is eliminated so as to attain clamping state, the clamping is released by applying an electric field and then the element is expanded by releasing the electric field to the distortion element 51. Then a distortion element 41' is moved to the right. The change of the moving direction to the right of the mobile body 30 is changed by repeating sequentially the operation is attained by changing the order of the electric field applied to the distortion element. On the other hand, the mobile body 30 is moved by the vibration of vibrators 21, 21'. Thus, the mobile body 30 is operated as the ultrasonic wave drive motor or as an actuator of the span worm system.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to an actuator that can easily perform large stroke and highly accurate positioning [Technical background of the invention and its problems] The actuators used in Elm equipment are mainly based on electromagnetic motors. Motors that utilize electromagnetism have been used as power sources in various fields for over 100 years, and many have large driving force, good electrical-to-mechanical conversion efficiency, and are highly reliable. .

In recent years, linear motors have been actively developed and are used in many fields such as AV equipment. However, in recent years, in various devices mainly used in the semiconductor industry, actuators that utilize electrostriction or inverse piezoelectric effects have come to be used as actuators that can control the position of micrometer-order or sub-micrometer processing. However, in piezoelectric actuators, the bimorph type has a maximum displacement of ~1
For the laminated type, the limit for practical use is 0 and 2 degrees. As a method to solve these problems, an inchworm type actuator has been devised and put into practical use.

However, although such inchworm method allows fine control, the actuator also has drawbacks such as slow response speed. l) A typical inchworm type actuator requires seconds to move one point.

Therefore, it is impossible to apply it as an actuator that moves at high speed with a large stroke. In addition, ultrasonic drive motors, which have recently attracted attention as piezoelectric actuators, have high efficiency and a large output for p1 movement, so they can be made into small actuators, but the positioning accuracy is equivalent to that of conventional electromagnetic motors.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and it is possible to perform coarse movement and fine movement using actuators based on different principles, and to perform high-precision positioning at high speed while allowing long strokes. The purpose is to provide a small and highly efficient actuator.

[Summary of the invention]

The present invention is an actuator characterized by comprising a moving body composed of a strain element and moving in an inchworm manner, and an ultrasonic drive motor for moving a pre-starting body.

In other words, the coarse movement of the moving object is performed by an ultrasonic drive motor, and the fine movement is the inchworm movement (inchworm movement) of the moving object itself.
This is an actuator that enables high-speed and high-precision movement by moving the actuator.

First, the principle of an ultrasonic drive motor is shown in FIG.

FIG. 1 fa) is a schematic diagram showing an example of an ultrasonic drive motor, which includes an elastic body (1) and a vibrator (2) fixed at both ends.

+ ('2') and a moving object (which corresponds to the rotor of a general motor)
It consists of the following three elements: This moving body is pressurized so as to be in close contact with one elastic body in order to efficiently transmit the traveling waves generated in the elastic body.

Figure 1(b) is a partially enlarged schematic perspective view for explaining the driving principle of the ultrasonic drive motor. X @ is an elastic body (
1) Let the direction on the surface, Z@, be its helix direction. When vibration is applied to the surface of the elastic body (1) by the electrostrictive elements (2) and (2'), elastic waves are generated and propagate on the surface of the elastic body (1). This elastic wave is a surface wave accompanied by longitudinal waves and transverse waves, and the motion of the mass point oscillates in an elliptical orbit. Focusing on mass point A, the vertical amplitude U.

If the inertial movement fijJ'fI of the lateral amplitude W is performed and the traveling direction of the surface wave is '6+x direction, the elliptical motion rotates counterclockwise. This surface wave has a vertex A for each wavelength,
A..., whose apex velocity is only the X component, and ■
−2πfU (where ■: moving speed, f is frequency). Therefore, when the surface of the moving body (3) is brought into pressure contact with this surface wave, the surface of the moving body will contact only the vertices A, A', etc., so the moving body (3) will be affected by the frictional force with the elastic body (1). Yoshi arrow N
It will be driven in the direction of.

Now, as a vibrator for generating this traveling wave, a Langevin type vibrator used in an ultrasonic processing machine or the like is suitable, and one vibrator is used at each end of the elastic body (1) to determine the direction of the traveling wave.

A strain element that moves in an inchworm method is used as a moving object that is moved by this ultrasonic drive motor.

The strain element consists of a piezoelectric element, an electrostrictive element, etc., and is basically a combination of three elements. Its basic configuration is shown in Figure 2. Strain element (
4) consists of elements fl) J2), +3), and if a piezoelectric element is used, for example, the polarity of the elements (1), [3) is determined so as to clamp the support (5) when the power is turned off. (Figure 2(a)). When driving, first, one of the clamped elements (3) is unclamped, and the element (2) connecting the two elements (4) J3) is extended (FIG. 2(b)).

+A41. ? +<64 Rui 4n Kazudai Masuji Shutsuzume ζzume, also λ? Silk mael. Next, the element (3) is clamped and the percentage
If you release the clamp on element (1) and let element (2) move, you will get a displacement of δ in Figure 5 (Figure 2 (C)).In general, a moving object that is displaced by an ultrasonic drive motor is 5. Pressure using a screw or the like is required to ensure adhesion with the elastic body. However, when using an inch worm type moving body, when assembling it, if the elastic is inserted in the contracted state and the clamped state is used, there is no need to attach a pressure mechanism, and assembly is easy. Furthermore, wear of the elastic body over time is a possibility, but since the pressing force in the clamped state can be changed depending on the applied voltage, etc., there is no need to provide a separate adjustment mechanism. Furthermore, in a normal ultrasonic drive motor, since the moving body is fixed to an elastic body, it can only self-lock (position is fixed when off). polarity,
By controlling the applied voltage, locking, free locking, and self-locking are all possible.

〔Effect of the invention〕

According to the actuator of the present invention described above.

(1) Long strokes and high-precision positioning can be controlled with a single actuator.

(2) Both the ultrasonic drive motor and the strain element have high efficiency, resulting in an overall highly efficient actuator.

(3) Since it does not generate an electromagnetic field, it can be used in environments where electromagnetic fields are disliked.

Taking advantage of the above characteristics, it is suitable as an actuator for high-speed, high-precision positioning under adverse environments.

[Embodiments of the invention]

The present invention will be described in detail below. FIG. 3 is a schematic cross-sectional view for explaining an embodiment of the actuator according to the present invention. In Figure 3, the elastic body (1υ is a brass piece with a diameter of 10mm and a vibrator of 0υ).

(21') are Languevin type piezoelectric vibrators each having a resonance frequency of about 28 KHz. An electromagnetic type vibrator is also possible, but a piezoelectric type is preferable if the vibrator has low power. The moving body C3@ is arranged so as to have appropriate adhesion to the elastic body αυ.

With this configuration, the moving object (to) can be moved by imaging the transducer t2 (21').

The moving body (30) has strain elements 0υ, (41'), (51
) and the case (3υ), and the strain element (41) is fixed to the case (31).
The strain element (5]) and the strain element (2') are arranged in series to enable inchworm operation. In this embodiment, piezoelectric elements are used as the strain elements (41), (41'), and (2), and the piezoelectric elements are PZT-based. Further, it is also possible to use other electrostrictive materials or magnetostrictive materials as the strain element. This strain element (41), (
41') and (51) are configured to contract when the power is turned off. The clamp strain element clamps the elastic body θυ when no current is applied. Moving object (to) is 3
Bidirectional movement is possible by appropriately controlling the two strain elements. The strain elements (41) and (41') are ring-shaped elements, and electrodes are attached to the outside as well as the inside where the ring contacts the elastic body, and the ring is configured to expand when an electric field is applied. has been done. The strain element (51) is a cylindrical element with electrodes provided at both ends of the cylinder, and is configured to contract by applying an electric field to both ends of the cylinder. Here, when an electric field is applied to the strain element (41) and the clamp is released, and an electric field is applied to the strain element (51), the strain element (41) moves to the right in Fig. 2 due to the contraction of the strain element (51). The electric field of the strain element (41) is removed and the strain element (41) is placed in a clamped state.
Apply an electric field to 41 to release the clamp and transform the primary strain element (
51) is released and extended, then the strain element (4
1') moves to the right. By repeating this motion sequentially, the moving object (to) moves to the right. To change the direction of movement, change the order of the electric fields applied to these distortion elements. can.

As described above, the moving body (30) can operate both as an ultrasonic drive motor and as an inchworm-type actuator. Therefore, long strokes and highly accurate positioning are possible, and conventional two actuators can be easily realized.

Although this actuator has been described using a linear type actuator as an example, a rotary type actuator is also possible. In addition, the positioning resolution of the inchworm type actuator is 01 to 0.05μ.
The piezoelectric type used in this embodiment can move 5 μm with a power source of approximately IVV, and therefore, quick positioning is possible.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the principle of an ultrasonic drive motor used in the present invention, and FIG. 2 is a schematic diagram for explaining the principle of an inchworm type moving body. FIG. 3 is a schematic cross-sectional view of an actuator for explaining the present invention in detail. Agent Patent attorney Kensuke Norichika (1 or 1 person) Figure 1 2' f Figure 2

Claims (1)

[Claims] An actuator comprising: a moving body configured with a strain element and moving in an inchworm manner; and an ultrasonic drive motor for moving the moving body.