JPH03203571A - piezoelectric actuator - Google Patents

Abstract

PURPOSE:To obtain large shifting speed and stable operation by arranging a second piezoelectric oscillator on a first piezoelectric oscillator, and bringing a mover into contact with the driver on the second piezoelectric oscillator. CONSTITUTION:When a first piezoelectric oscillator 1 is electrically driven, physical elongation occurs in the direction of an arrow a, and this holds up a mover 4 slightly through a driver 3 while pushing and bending a second piezoelectric oscillator 2. Next, the second piezoelectric oscillator 2 is electrically driven, it elongates in the direction of an arrow b, so the mover 4 moves straight in the direction of an arrow c by the amount that the second piezoelectric oscillator has elongated horizontally. Next, when the driving of the first piezoelectric oscillator 21 is stopped and it is shrunk in the direction of an arrow d, the driver 4 separates slightly from the mover 4 while the shifter 4 left behind at the moving point by inertia. Furthermore, when the driving of the piezoelectric oscillator 2 is stopped and shrunk, the first and second piezoelectric oscillators 1 and 2 return to the original states, and the mover 4 also returns below.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a piezoelectric actuator using a piezoelectric vibrator.

(Conventional technology) Traditionally, piezoelectric ceramics and electrostrictive ceramics.

Piezoelectric actuators using displacement elements made of polymeric piezoelectric materials or composite materials thereof are known.

For example, there are bimorph type and Langevin oscillators, but these displacement elements have a small displacement of several micrometers to several micrometers, and are unsuitable for use in applications requiring a large displacement. There is a piezoelectric actuator called an inchworm that can compensate for this amount of displacement, but since it is basically moved by mechanical movement, the driving frequency cannot be increased very much, so a high moving speed cannot be expected, and it is only about several cm/minute. Furthermore, since the structure requires high precision, errors on the order of several μm greatly affect performance, resulting in problems such as non-operation or unstable operation. Further, since the mechanical contact is made intermittently, there is also the problem that the generation of noise is unavoidable.

There is also an ultrasonic motor called an elastic traveling wave type.
Since an elastic traveling wave is generated on the elastic rail, there is a strict relationship between the drive frequency and mechanical dimensions, and the mechanical dimensions accuracy is particularly strict and adjustment is difficult. Furthermore,
It also has drawbacks such as not working or becoming unstable due to changes in the drive frequency or the resonant frequency of the piezoelectric vibrator.

Furthermore, as mentioned above, there is a strict relationship between the drive frequency and mechanical dimensions, so it is necessary to increase the drive frequency in order to miniaturize the piezoelectric vibrator. In terms of efficiency, the driving frequency of the elastic traveling wave type ultrasonic motor is no more than 80 KHz at the highest, and it has been extremely difficult to miniaturize it.

(Problems to be Solved by the Invention) As mentioned above, conventional piezoelectric actuators have a small displacement or movement amount, whereas inchworm or elastic traveling wave ultrasonic motors that have a large movement amount have mechanical dimensions. The tolerance range was small, and stable operation could not be obtained due to changes in the drive frequency or changes in the resonant frequency of the vibrator.

Furthermore, the inchworm had problems such as generation of noise due to intermittent mechanical contact, and the difficulty of downsizing the elastic traveling wave type ultrasonic motor.

The present invention aims to eliminate the above-mentioned drawbacks and provide a piezoelectric actuator that does not require much mechanical precision, has a simple control circuit, can provide high movement speed and stable operation, and can be miniaturized. It is.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a first piezoelectric vibrator that performs longitudinal vibration or thickness vibration, and a first piezoelectric vibrator that performs transverse vibration and/or spreading vibration, or longitudinal vibration or thickness vibration. a second piezoelectric vibrator that is in contact with the first piezoelectric vibrator; a piezoelectric actuator consisting of a moving body arranged so as to be in contact with the piezoelectric actuator, and a piezoelectric actuator that uses a piezoelectric vibrator that vibrates horizontally and/or spreads as the first piezoelectric vibrator, and vibrates longitudinally or through thickness as the second piezoelectric vibrator. , or a piezoelectric actuator that uses transverse vibration and/or spreading vibration.

(Function) In the piezoelectric actuator according to the present invention, the second piezoelectric vibrator is disposed on the first piezoelectric vibrator, and the movable body in contact with the driving body on the second piezoelectric vibrator is Even if the amplitude of the piezoelectric vibrator is small, a high moving speed can be obtained. In addition, unlike surface wave type ultrasonic motors, which do not utilize resonance characteristics, there are no restrictions on structural dimensions, and the speed can be varied over a wide range by changing the frequency.

(Example) FIG. 1 is a block diagram of the present invention. One side of the first piezoelectric vibrator 1 that vibrates vertically, through the thickness, or vibrates horizontally and/or spreads is fixed to the base 5, and each part of the first piezoelectric vibrator 1 other than this fixed side is free. The electrode 1a attached to the surface of the first piezoelectric vibrator 1 that is not fixed to the base 5 is kept in a state where it can be expanded and contracted, and vertical vibration, thickness vibration, lateral vibration and/or The second piezoelectric vibrator 2 is attached so that the vicinity of the periphery of the electrode 2b attached to one surface of the second piezoelectric vibrator 2, which vibrates in a spreading manner, is located. Further, a driving body 3 is attached to the other surface of the second piezoelectric vibrator 2, and a movable body 4, which is a driven body, is brought into pressure contact with this driving body 3, and electric signals for driving these piezoelectric vibrators are applied. It has a configuration in which the vibrations of these piezoelectric vibrators are transmitted as the moving force of the movable body 4 by giving a phase difference to the piezoelectric vibrators. The operation of the piezoelectric actuator having this configuration will be explained based on FIG. 2. As shown in FIG. 2(a), when the first piezoelectric vibrator 1 is electrically driven, this piezoelectric vibrator 1 physically stretches in the direction of arrow A, and the second piezoelectric vibrator 1
While pushing and bending the piezoelectric vibrator 2, the movable body 4 is slightly lifted via the driving body 3. Next, as shown in FIG. 2(b), when the second piezoelectric vibrator 2 is electrically driven while the first piezoelectric vibrator 1 is being driven, the second piezoelectric vibrator 2 Since it extends in the mouth direction, the movable body 4 moves linearly in the direction of arrow C by the amount that the second piezoelectric vibrator 2 extends in the horizontal direction. Next, as shown in FIG. 2(C), driving of the first piezoelectric vibrator 1 is stopped while driving the second piezoelectric vibrator 2, and the first piezoelectric vibrator is contracted in the two directions indicated by the arrows. If you do this, the first
Since the contraction of the piezoelectric vibrator 1 in the two directions indicated by the arrows takes place within a very short time, the driving body 3 leaves the movable body 4 only a little while the movable body 4 is left behind at the moving point due to inertial force. Furthermore, as shown in FIG. 2(d), when the drive of the piezoelectric vibrator 2 is stopped and the piezoelectric vibrator 2 is contracted in the direction of the small arrow, the first. The second piezoelectric vibrator 1.2 returns to its original state, and the movable body 4 left behind at the moving point also returns downwards due to inertia. A series of drive cycles is completed in the state of movement in the direction. By repeating this operation, the moving body 4 moves continuously in the direction of arrow C in FIG. 2(b).

Example 1 FIG. 3 is a perspective view showing an embodiment of the present invention.

One side of a first piezoelectric vibrator 1 made of a piezoelectric ceramic whose main component is PZT, barium titanate, etc. and which vibrates longitudinally or through thickness is fixed to a base 5 with an adhesive. The second piezoelectric vibrator 2 is stacked so that the vicinity of the periphery of the electrode of the second piezoelectric vibrator 2 is located near the center of the electrode attached to the other surface of the first piezoelectric vibrator 1, and In the second piezoelectric vibrator 2 that vibrates through its thickness, one end of the side that does not overlap with the first piezoelectric vibrator is bonded to the base 5 with an adhesive. Further, a driving body 3 made of a metal plate is adhesively fixed to the other surface of the second piezoelectric vibrator 2, a moving body 4 is arranged so as to be in contact with the other surface of the driving body 3, and a housing 6 is mounted.
A leaf spring 7 installed inside pressurizes the movable body 4 against the driving body 3.

In this state, when the electric waveform shown in FIG. 4(a) was applied to each piezoelectric vibrator to drive it, the movable body 4 performed linear motion as described above. At this time, the mass point of the driving body 3 draws a motion locus as shown in FIG. 5(a) by combining the motion vectors of the piezoelectric vibrator 1 and the piezoelectric vibrator 2, and When the electric waveform shown is applied to each piezoelectric vibrator 1.2 to drive it, the locus of mass motion of the driving body will be as shown in FIG. The moving body 4 in pressure contact performs linear movement along the rotational direction of rectangular or circular motion.

According to this embodiment, when the driving signal frequency is 16 KHz using the pulsed driving method shown in FIG. Obtained.

Note that, in practice, the piezoelectric actuator can operate at a driving frequency in the range of several yen Z to 300 KHz.

Further, in the above description, the driving body is made of metal, but other materials may be used as long as force can be transmitted, and any material such as metal, ceramic, polymer, etc. can be used.

The piezoelectric vibrator may be a single plate or a laminate of piezoelectric ceramic, electrostrictive ceramic, or piezoelectric polymer.

Example 2 As shown in FIGS. 6 and 7, a first piezoelectric vibrator 1 that performs longitudinal vibration or thickness vibration, and a second piezoelectric vibrator that performs transverse vibration and/or spreading vibration are used. This is an example used. This embodiment is the same as the first embodiment except for the difference in the vibration directions of the first and second piezoelectric vibrators.

Example 3 As shown in FIGS. 8 and 9, a first piezoelectric vibrator 1 that performs transverse vibration and/or spreading vibration, and a second piezoelectric vibrator that performs longitudinal vibration or thickness vibration are used. This is the example used, and the other configurations are the same as Example 1.

Example 4 As shown in FIGS. 10 and 11, this is an example in which the first and second piezoelectric vibrators 1 and 2 are those that perform transverse vibration and/or spreading vibration, respectively. The second embodiment is the same as the first embodiment except for the difference in .

[Effects of the Invention] The piezoelectric actuator according to the present invention has a simple configuration, is small and lightweight, has high reliability, and is independent of frequency, so it is stable and highly controllable.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, and FIGS.
8 and 10 are block diagrams showing examples of piezoelectric actuators, FIG. 2, FIG. 7, FIG. 9, and FIG. 11, respectively.
The figures are principle diagrams showing the operating order of the piezoelectric actuator of each embodiment, Fig. 3 is a perspective view showing one embodiment of the piezoelectric actuator, Fig. 4 is a timing diagram of drive waveforms, and Fig. 5
The figure is a locus of motion of a mass point induced in a driving body when a piezoelectric actuator is driven. 1...First piezoelectric vibrator 2...Second piezoelectric vibrator 3...Driving body 4...Moving body 5...Base Patent application Hito Marukon Electronics Co., Ltd. 2 Piezoelectric actuator Fig. 3: Timing diagram of drive waveforms Fig. 4: Motion locus of mass point Fig. 5: Principle of piezoelectric actuator operating sequence Fig. 9: Fig. 0: Fig. 1

Claims (2)

[Claims] (1) A first device that performs longitudinal vibration or thickness vibration with one surface fixed.
a piezoelectric vibrator, and a transverse vibration and/or spreading vibration arranged over the first piezoelectric vibrator so that the vicinity of the periphery of the electrode on one side is located near the center of the electrode of the first piezoelectric vibrator. a second piezoelectric vibrator that vibrates or vibrates longitudinally or through thickness, and a driving body that is in contact with a surface of the second piezoelectric vibrator that is different from the surface that is in contact with the first piezoelectric vibrator; A piezoelectric actuator comprising a moving body arranged so as to be in contact with the other surface of the driving body. (2) A first piezoelectric vibrator that performs transverse vibration and/or spreading vibration, and longitudinal vibration or A second piezoelectric vibrator that vibrates through thickness, or vibrates in transverse vibration and/or spread vibration, and the second piezoelectric vibrator is in contact with a surface different from the surface in contact with the first piezoelectric vibrator. A piezoelectric actuator comprising a driving body and a moving body disposed in contact with another surface of the driving body.