JPH03235676A - Piezoelectric actuator - Google Patents

Abstract

PURPOSE:To obtain a large moving speed and a stable movement by a method wherein a phase difference is provided between signals which drives respective piezoelectric transducers to induce the material particle movement of a driving unit and a moving unit is moved by utilizing the mass-center movement. CONSTITUTION:If respective piezoelectric transducers 1, 1' and 2 are driven by applying protruding waveforms to them, a moving unit 4 shows a linear movement. At that time, the material particle of a driving unit 3 draws a rectangular trace by the resultant vector of motion vectors of the first piezoelectric transducers 1 and 1' and the second piezoelectric transducer 2. Further, if the first piezoelectric transducers 1 and 1' and the second piezoelectric transducer 2 are driven by applying sinusoidal electric waveforms to them, the material particle movement of the driving unit draws a circular trace. Therefore, the moving unit 4 which is brought into contact with the driving unit 3 by compression shows a linear movement along the direction of a rectangular or circular motion.

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 displacement of several micrometers to several orders of magnitude, 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 1/min. Furthermore, since the structure requires high precision, errors on the order of several micrometers greatly affect performance, resulting in failure 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 an elastic rail, there is a strict relationship between drive frequency and mechanical dimensions, and in particular, mechanical dimension accuracy is strict and adjustment is difficult. Furthermore, there are also drawbacks such as non-operation or unstable operation due to changes in the drive frequency or resonance 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 downsize, but the characteristics of the piezoelectric vibrator and the width of the energy that can be extracted 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 the motor.

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

The present invention includes at least two first piezoelectric vibrators fixed side by side on a base, and a first piezoelectric vibrator arranged astride the first piezoelectric vibrators adjacent to each other on the other side of the first piezoelectric vibrators. This piezoelectric actuator is composed of a second piezoelectric vibrator, a driving body disposed on the other surface of the second piezoelectric vibrator, and a movable body disposed in contact with the driving body. The idea is to cause a mass point movement in the driving body by giving a phase difference to the signal that drives the vibrator, and to use this mass point movement to move the moving body.

(Function) The piezoelectric actuator of the present invention straddles at least first piezoelectric vibrators arranged side by side on a base and a first piezoelectric vibrator adjacent to the other surface of the first piezoelectric vibrators. The movable body can be moved intermittently or continuously by the second piezoelectric vibrator arranged in the same direction. In addition, unlike surface wave type ultrasonic motors, the motor does not utilize resonance characteristics, so there is no structural dimension restriction, and the speed can be varied over a wide range by changing the frequency.

(Example) FIG. 1 shows a configuration diagram of the present invention. That is, a plurality of first piezoelectric vibrators 1 and 1' that perform longitudinal vibration and/or thickness imaging, or horizontal and/or spread vibration are fixed on the base 5, and the piezoelectric vibrators other than the fixed surface are fixed. Each part of the vibrator is kept in a free state, and images are taken horizontally and/or spread out so as to be located across the adjacent piezoelectric vibrators 1 and 1', or vibrated vertically and/or thickness. The second piezoelectric vibrators 2 are placed one on top of the other. 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 the driving body 3, so that these first piezoelectric vibrators 1 , 1' and the second piezoelectric vibrator 2 have a phase difference, so that the first piezoelectric vibrator 1°1' and the second piezoelectric vibrator 2 are driven by the moving body 4. It has a configuration that transmits it as a moving force. The operating principle 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 While pushing and bending the moving body 2, the moving 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 convex direction of the arrow by the amount that the second piezoelectric vibrator 2 extends in the horizontal direction.

Next, as shown in FIG. 2(C), the second piezoelectric vibrator 2
Stop driving the first piezoelectric vibrator 1 while driving the first piezoelectric vibrator 1, and
When the first piezoelectric vibrator 1 is contracted in the two directions indicated by the arrows, the contraction of the first piezoelectric vibrator 1 in the two directions indicated by the arrow occurs in an extremely short time, so that the movable body 4 is left behind at the moving point due to inertial force. The driving body 3 moves slightly away from the movable body 4 while remaining in the position.

Furthermore, as shown in FIG. 2(d), when the drive of the second piezoelectric vibrator 2 is stopped and it is contracted in the direction of the arrow mark, the piezoelectric vibrator 1.2 returns to its original state and The moving object left behind at the moving point returns to the bottom due to inertia, so moving object 4 to the second
A series of drive cycles is completed in the state of movement in the convex direction of the arrow in FIG. 3(b). By repeating this operation, the moving body 4 moves continuously in the convex direction of the arrow in FIG. 2(b).

Next, as shown in FIG. 2(e), when the other first piezoelectric vibrator 1' is electrically driven, this piezoelectric vibrator 1' physically stretches in the direction of the arrow. , second piezoelectric vibrator 2
While pushing and bending, the movable body 4 is slightly lifted via the drive body 3.

Next, as shown in FIG. 2(f), when the second piezoelectric vibrator 2 is electrically driven while the other first piezoelectric vibrator 1' is being driven, the second piezoelectric vibrator 2 extends in the direction of arrow T, so the movable body 4 moves linearly in the direction of arrow H by the amount that the piezoelectric vibrator 2 extends in the horizontal direction. This is the direction opposite to the direction of the moving body shown in FIG. 2(b), indicated by the arrow C.

Next, as shown in FIG. 2(Q), the second piezoelectric vibrator 2
If you stop driving the other first piezoelectric vibrator 1' while driving the piezoelectric vibrator 1' and contract this piezoelectric vibrator 1' in the direction of the arrow, the contraction of the piezoelectric vibrator 1' in the direction of the arrow will be extremely Since this is done in a short time, the driving body 3 moves slightly away from the movable body 4 while the movable body 4 is left behind at the moving point due to inertial force.

Furthermore, as shown in FIG. 2(h), when the driving of the second piezoelectric vibrator 2 is stopped and the second piezoelectric vibrator 2 is contracted in the direction of the arrow ``nu'', the other first piezoelectric vibrator 1' and the second piezoelectric vibrator 2 are The vibrator 2 returned to its original state, and the movable body 4 left behind at the moving point also returned to the bottom due to inertia, so the movable body 4 was moved in the direction of the arrow in Fig. 2(f). A series of drive cycles ends in this state. In this case, the moving direction H of the moving body 4 is opposite to the moving direction C in FIG. 2(b), which means that the moving body 4 can easily move backward. By continuously repeating this series of cycles, the moving body 4 moves continuously.

Therefore, Fig. 2(a) to (d) and Fig. 2(e) to (
By repeating h), movement in the same direction can be realized. Moreover, by repeating the steps in FIGS. 2(a) to 2(h), reciprocating motion can be obtained at the same location. In addition, the first
The same effect can be obtained by using a piezoelectric vibrator that performs transverse vibration and/or spreading vibration as the second piezoelectric vibrator, and using one that performs longitudinal vibration and/or thickness vibration as the second piezoelectric vibrator.

! FIG. 3 is a perspective lateral view showing one embodiment of the present invention. below,
An example will be described using this figure.

First piezoelectric vibrators 1.1', which are made of piezoelectric ceramics whose main components are PZT, barium titanate, etc., and which perform vertical and/or horizontal imaging, are arranged and fixed to the base 5 by adhesive. Straddling these two piezoelectric vibrators 1 and 1', one end of the first piezoelectric vibrator 1 has a maximum amplitude, that is, near the center of the electrode, and the other end of the first piezoelectric vibrator 1 has a maximum amplitude. A second piezoelectric vibrator 2 that vibrates vertically and/or thickness is stacked so as to be located near the center of the electrode of the element 1', and the second piezoelectric vibrator 2 and the first piezoelectric vibrator 1°1' The overlapping surfaces are glued and fixed.

A driving body 3 made of a metal plate is adhered and fixed to the other side of the second piezoelectric vibrator 2, and a moving body 4 is arranged on the other side of the driving body 3, and is installed inside the housing 6. flat spring 7
The movable body 4 is pressurized 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 is located between the first piezoelectric vibrator 1 and the second piezoelectric vibrator 1.
Figure 5 (
Draw a motion trajectory as shown in a), and also draw a motion trajectory as shown in Figure 4 (
When the electric waveform shown in b) is applied to each of the first piezoelectric vibrator and the second piezoelectric vibrator 2 and driven, the driving body 3
Since the locus of mass point motion is as shown in Fig. 5(b), the movable body 4 in pressure contact with the driving body 3 moves linearly along the rotational direction of rectangular or circular motion. .

According to this example, when the driving signal frequency was set to 16 KHz using the pulsed driving method shown in FIG. 4(a), a moving speed of approximately 12 m*/Sec was obtained with an element amplitude of 1.0 μm. .

Example 2 An example will be described in which a first piezoelectric vibrator that performs vertical and/or thickness imaging is used, and a second piezoelectric vibrator that performs horizontal and/or spread vibration is used. FIG. 6 shows a configuration diagram, and FIG. 7 shows a diagram of the operating principle.
Performs the same operation as .

Example 3 This is an example in which the first piezoelectric vibrator is one that vibrates horizontally and/or spreads, and the second piezoelectric vibrator is vibrates vertically and/or thickness. The configuration diagram and the operating principle diagram are shown in Fig. 9.

Its operation is similar to that of the first embodiment.

Example 4 This is an example in which the first piezoelectric vibrator and the second piezoelectric vibrator vibrate horizontally and/or spread, respectively. Fig. 10 shows the configuration diagram, and Fig. 11 shows the principle of operation. shows.

Its operation is similar to that of the first embodiment.

Since the piezoelectric actuator according to the present invention does not utilize resonance characteristics like a surface wave type ultrasonic motor, there is no structural dimension restriction, and the driving frequency is not limited to the 16 KHz of this embodiment. The speed can be varied over a wide range by changing the frequency.

Practically, it can operate as a piezoelectric actuator in the range of several H2 to 300 KHz.

In addition, although the driving body is made of metal, other materials may be used as long as the force can be transmitted, such as metal, ceramic, etc.
Any material such as a polymer can be used. And the piezoelectric vibrator is a piezoelectric ceramic.

A single plate or a laminate of electrostrictive ceramics or piezoelectric polymers may be used.

Furthermore, in this example, one pressure is placed on two piezoelectric vibrators!
Although we have shown the structure of overlapping ffr pins, it is also possible to have multiple piezoelectric vibrators stacked on top of a plurality of piezoelectric vibrators arranged in a band shape at the bottom, or to arrange multiple piezoelectric vibrators in a flat shape. It goes without saying that you can get the same effect with anything.

[Effects of the Invention] The piezoelectric actuator according to the present invention has a simple structure, is small in size, is lightweight, has extremely high reliability, and is not dependent on frequency, so it is stable and highly controllable.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, and FIG. FIG. 6, FIG. 8, and FIG. 10 are block diagrams, FIG. 2, and FIG. 7, respectively, showing embodiments of the piezoelectric actuator. Figures 9 and 11 are principle diagrams explaining the operating order of the piezoelectric actuator, Figure 3 is a perspective view showing an embodiment of the piezoelectric actuator, Figure 4 is a timing diagram of drive waveforms, and Figure 5 is a drive waveform diagram. FIG. 4 is a diagram showing the locus of motion of a mass point induced in a driving body when 1 ′...First piezoelectric vibrator 2...Second piezoelectric vibrator 3...
...Driving body 4...Moving body 5...Base Patent applicant Marukon Electronics Co., Ltd. 1' Principle of operation sequence of piezoelectric actuator 2nd diagram Piezoelectric Actuator configuration diagram Figure 1 Figure (a) Timing diagram of drive waveform Figure 4 Motion locus diagram of mass point Figure 5 Piezoelectric actuator 6 Configuration diagram Principle of piezoelectric actuator operating sequence Figure 7 Figure

Claims (4)

[Claims] (1) At least two first piezoelectric vibrators that perform longitudinal vibration and/or thickness vibration, or transverse vibration and/or spread vibration, which are fixed side by side on a base; vertical vibration and/or thickness vibration, or transverse vibration and/or
Or a piezoelectric actuator comprising a second piezoelectric vibrator that performs spread vibration, a driving body disposed on the other surface of the second piezoelectric vibrator, and a movable body disposed in contact with the driving body. (2) The piezoelectric actuator according to claim (1), wherein both ends of the second piezoelectric vibrator are located at a maximum amplitude portion of the first piezoelectric vibrator. (3) The piezoelectric vibrator is a piezoelectric ceramic, an electrostrictive ceramic,
A claim consisting of a polymeric piezoelectric material or a composite thereof (1)
) or the piezoelectric actuator according to claim (2). (4) The piezoelectric actuator according to any one of claims (1) to (3), wherein the piezoelectric vibrator is formed of a laminate.