JPS6132487A - Bimorph electrostriction oscillation device - Google Patents

Abstract

PURPOSE:To obtain the titled device of self-latch system which is mechanically stable because of a large displacement and can prevent the break of the oscillator even when an excessive outer force is exerted, by a method wherein, using a magnetic substance for the center electrode and arranging a fixed magnetic substance at the opposed position, the displacement-generating force characteristic is improved by the suction forces thereof. CONSTITUTION:When a positive voltage is impressed on electrodes 5 and 6 and a negative voltage on a center electrode 2, an end 1b of an oscillator 1 displaces from a position B to a displacement reaching point A by the resultant of the generating force of the oscillator 1 and the suction force between the center electrode 2 and a permanent magnet 9-1, and is then kept stably in a mechanical manner at this displacement reaching point. Next, when the voltage is inversed, the generating force of the oscillator 1 acting to the lower direction of the drawing overcomes the suction force and the restoring force of the center electrode 2; accordingly, the end 1b of the oscillator 1 displaces downward from the displacement reaching point A. Then, said end displaces to a displacement reaching point C by the resultant of the generating force and the suction force between the center electrode 2 and a permanent magnet 9-2, and is stably kept in a mechanical manner at this displacement reaching point.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrostrictive vibration device, and particularly relates to a displacement and vibration device.
This invention relates to an electrostrictive vibration device with improved force generation characteristics.

[Background technology]

Bimorph electrostrictive vibration devices have recently been studied in many fields as an alternative to electromagnets. However, since the displacement and force characteristics are significantly different from those of electromagnets, operational stability may become a problem.

Referring to FIG. 2, a bimorph electrostrictive vibrator 1' is formed by stacking ferroelectric electrostrictive plates 3 and 4 with a central electrode 2' in between. Note that 5 and 6 are electrodes. An end 1'a of the vibrator 1' is fixed to a support member (not shown), and the other end 1'b swings by applying a voltage to the electrodes 2', 5.6. It is. Not indicated by the broken line in the figure■
is the position of the end 1'b of the vibrator 1' when no voltage is applied, ■ is the displacement point when a voltage is applied, and ■ is the position when a voltage with the opposite polarity is applied. Indicates the displacement point.

In other words, in the state of ■, the voltage is reversed, and the end 1'b of the vibrator 1' is displaced by an amount A, as shown by the arrow in the figure, and the displacement and generated force until the state of ■ is reached. The characteristics are shown in Figure 2 fbl. As shown between the nuclei, the generated force F is greatest when δ=0, and when the displacement δ-A, that is, at the displacement reaching point, F=O.

Therefore, at the displacement reaching point, it becomes mechanically unstable against impact force and the like. Therefore, when displacing on both sides and trying to secure a constant force, it is necessary to restrain the displacement at a point shorter than A, but this means sacrificing the amount of displacement, and there is no need to increase the amount of displacement. undesirable considering.

In order to solve this problem, a technology to improve the displacement and generated force characteristics using magnets was proposed in Japanese Patent Application No. 59-75623 filed by the present applicant.
It is disclosed in "Electrostrictive Vibration Device Driving Circuit" of . FIG. 3 shows an example of its configuration. As shown in FIG. 3 (al), the magnetic body 13 is fixed to the end portion 1''b of the vibrator 1#, and the magnetic body 9'' is fixed in the vicinity of the displacement reaching point of the magnetic body 13. Either the magnetic body 13 or 9'' is a permanent magnet.The generated force of this bimorph electrostrictive vibrator is the sum of the generated force of the vibrator 1'' and the magnetic body, as shown in FIG. 3 (bl). Displacement due to the combined force of the suction force between 13 and 9
The force generation characteristics are improved.

[Problem that the invention seeks to solve]

However, as shown in FIG. 3 (al), the structure in which the magnetic body 13 is attached to the tip of the vibrator 1" has drawbacks in terms of accuracy and poor manufacturability. Also, it is difficult to extract the acting force. There is also the problem of a lack of mechanical reliability because the force of the magnet is concentratedly applied to the tip.

[Purpose of the invention]

In view of the above-mentioned objectives, this invention aims to: 1) obtain a large displacement, 2) be mechanically stable at the displacement point when voltage is applied, and 2) enable self-latching even when voltage application is stopped. The object of the present invention is to provide a bimorph electrostrictive vibrating device that achieves the following: (1) preventing the vibrator from being destroyed due to excessive external force;

[Means for solving problems]

In order to achieve the above object, the present invention fixes one end of a bimorph electrostrictive vibrator made by stacking a plurality of ferroelectric electrostrictive plates each having electrodes on both sides, and fixes one end of the bimorph electrostrictive vibrator by applying a voltage to the electrodes. In a bimorph electrostrictive vibrator configured to displace an end, at least one of the electrodes is made of a magnetic material, and comes into contact with the vicinity of the other end of the electrostrictive vibrator to keep the displacement of the other end within a rupture limit displacement range. By fixing a displacement restraining member that can be restrained in a swinging manner, fixing a fixed magnetic body near the displacement restraining member, and magnetizing at least one of the electrode made of the magnetic body and the fixed magnetic body. An attractive force characteristic is created between the electrode and the fixed magnetic body.

〔Example〕

An embodiment of this invention is shown in FIG. As shown between the cores, the bimorph electrostrictive vibrator 1 has a central electrode 2 formed of a permalloy magnetic spring, and is formed by stacking ferroelectric electrostrictive plates 3 and 4 with the central electrode 2 interposed therebetween. Note that 5 and 6 are electrodes.

An end portion 1a of the vibrator 1 is fixed to a support member 7, and the other end portion 1b is oscillated by applying a voltage to the electrodes 2, 5, and 6. The end portion 1b engages with another mechanism (not shown), and its displacement is transmitted to the mechanism.

A terminal 8 is provided connected to the electrodes 2, 5.6, and is connected to a drive circuit described later.

The displacement restraint member 9 (9-1, 9-2) is the vibrator 1
The vibrator 1 is fixedly installed near the displacement reaching point of the end 1b of the vibrator 1.
The displacement is constrained to the range between the normal displacement points indicated by ■ and ■. Further, permanent magnets 10 (10-1, 1O-2) are mounted in this displacement restraining member 9.

Next, the drive circuit of this bimorph electrostrictive vibration device will be explained. FIG. 4 shows a drive circuit connected to the bimorph electrostrictive vibration device of the embodiment shown in FIG. This drive circuit is disclosed in the aforementioned Japanese Patent Application No. 59/75623 filed by the present applicant, and only its outline will be explained here.

As shown in FIG. 4, the drive circuit consists of a DC power supply circuit, a constant voltage circuit, a polarity switching circuit, and a drive input circuit. In the figure, the arrows on the ferromagnetic electrostrictive plates 3 and 4 of the bimorph electrostrictive vibrator l indicate the polarization direction of the electrostrictive plates 3 and 4.

This operation will be explained.

The DC voltage output from the DC power supply circuit is input to the polarity switching circuit via the constant voltage circuit.

The polarity switching circuit allows the electrodes 5 and 6 to have positive and central polarity.
A negative voltage is applied to the electrode 2. At this time, an electric field is applied to the electrostrictive plate 3 in the same direction as the polarization direction, and a stress is generated inside the electrostrictive plate 3 that tends to contract in the longitudinal direction.

On the other hand, since an electric field is applied to the electrostrictive plate 4 in a direction opposite to the polarization direction, stress that tends to extend in the longitudinal direction is generated inside the electrostrictive plate 4. These stresses cause the vibrator 1 to be displaced upward in the figure.

Next, a negative voltage is applied to the electrodes 5 and 6, and a positive voltage is applied to the central electrode 2. At this time, the electrostrictive plates 3 and 4
An electric field is generated in the opposite direction to the above, and stress is generated in the opposite direction to the above. These stresses cause the vibrator 1 to be displaced in the downward direction in the figure.

At this time, if a voltage is applied to the electrostrictive plates 3 and 4 in the opposite direction to the polarization direction, the polarization characteristics will deteriorate and polarize at a polarization deterioration voltage lower than the dielectric breakdown voltage, and if the voltage is further increased, the polarization will be destroyed. However, there is a problem that the electrostrictive effect is lost.

Therefore, the constant voltage diode ZD of the drive input circuit,
,ZD,! Accordingly, the voltage applied to the electrostrictive plates 3 and 4 in the direction opposite to the polarization direction is set to a value lower than the polarization deterioration voltage.

Now, the operation of the bimorph electrostrictive vibration device will be explained with reference to FIG. 1 again.

■, which is indicated by a broken line in FIG. 1, is the position of the end 1b of the bimorph electrostrictive vibrator 1 when no voltage is applied to the electrodes 2, 5, and 6; ■ is the displacement point when voltage is applied; ■ does not indicate the displacement point when a voltage with reversed polarity is applied.

When a positive voltage is applied to the electrodes 5 and 6, and a negative voltage is applied to the center electrode 2, the end portion 1b of the vibrator 1 receives the force generated by the vibrator 1, the center electrode 2, and the permanent magnet 9-1.
Due to the resultant force of the attraction forces between them, it is displaced from the position (2) to the displacement point (2), and is held mechanically stably at the displacement point.

Next, when the voltage is reversed, that is, a negative voltage is applied to the electrodes 5 and 6, and a positive voltage is applied to the central voltage 2, the force generated by the vibrator 1 acting in the downward direction in the figure increases the attractive force and Overcoming the restoring force of the central electrode 2, the end portion 1b of the vibrator 1 is displaced downward from the displacement point (2). Then, due to the resultant force of the generated force and the attractive force between the central electrode 2 and the permanent magnet 9-2, it is displaced to the displacement reaching point (2), and is mechanically stably maintained at the displacement reaching point. Therefore, the end portion 1b of the vibrator 1 is
It is also possible to act on the other mechanisms at the displacement reaching points of (1) and (2). At this time, even if an external force is applied to the end 1b, the end 1b will not malfunction as long as the external force does not exceed the suction force holding the end 1b. Furthermore, when the suction force is set appropriately strong, even if the voltage application is stopped in a state where the end portion 1b is located at the displacement reaching point of the above-mentioned It is also possible to have a so-called self-latching function that overcomes this and holds the end portion 1b at the displacement point.

Furthermore, since the displacement range of the vibrator 1 is restrained by the displacement restraining member 9, even if an excessive external force is applied to the end portion 1b, the displacement does not exceed the breaking limit displacement range, and the mechanical is stable.

Further, in this embodiment, the contact surface of the restraining member 9 with the vibrator 1 is a flat surface, but the area is wider and the deflection of the vibrator 1 when in contact with the restraining member 9 is made larger. If the abutment surface is molded to match the shape, mechanical stability will be further increased.

Further, in this embodiment, the center electrode 2 is formed of a permalloy magnetic spring to improve the restoring force of the vibrator 1, but the center electrode 2 does not necessarily have to be a spring. In addition to permalloy, magnetic materials such as stainless steel and iron can also be used as materials.

Further, although the permanent magnet 10 is configured to be mounted on the displacement restraining member 9, the displacement restraining member may be formed of a plastic magnet made by mixing magnetic powder with resin and solidifying it.

Alternatively, a configuration may be considered in which the central electrode 2 is magnetized and 10 is simply a magnetic material.

Further, as shown in FIG. 5, the end portion 1b of the vibrator 1
As long as the displacement does not exceed the rupture limit displacement range B,
The displacement restraining member 9 may be located outside the displacement reaching range C in the case where there is no magnet. By doing so, the amount of displacement is further increased.

Furthermore, as shown in FIG. 6 (al), the vibrator 1 can be mounted in a housing to form a unit of the vibrator. 11 is a substrate, and lla is a vibrator support formed on the substrate. , 12 is a cover case.

Displacement is restrained by the stepped portion 3 of the substrate 11 and the protruding portion 12a of the cover case 12. Further, the step portion 1
permanent magnets 13 (13-1,
13, -2) is implemented.

Note that FIG. 6(b) shows the displacement/generated force characteristics of the vibrator 1 in this example.

Furthermore, in the above embodiments, a two-layer bimorph electrostrictive vibrator is used; however, for example, a multilayer bimorph electrostrictive vibrator disclosed in Japanese Patent Application No. 59-75623 by the applicant mentioned above may be used. Of course, it is also possible to use it.

〔Effect of the invention〕

As explained above, in this invention, a magnetic material is used for the center electrode, a fixed magnetic material is arranged at the opposing position, and the displacement and generated force characteristics are improved by the attraction force of these materials. It is large and mechanically stable, ■ It is easy to connect other mechanisms to the changing end of the bimorph electrostrictive vibrator, and ■ It is equipped with a displacement restraint member, so even if excessive external force is applied, the vibration will not be affected. There are effects such as being able to prevent the child from breaking, and making it a self-latching bimorph electrostrictive vibrator.

Due to these effects, Otsu's invention can be used in various fields as a substitute for electromagnetic magnets, and can be used as a driving part for coin processing equipment,
When summarized in relays, optical switches, etc., the effect is that it is possible to realize reliable devices that are small, lightweight, and low in power.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the invention. FIG. 2 and FIG. 3 are diagrams showing the background art. FIG. 4 is a diagram showing the driving circuit of the embodiment of FIG. 1. FIG. 5 and FIG. 6 are diagrams showing other embodiments of the invention. 1: Bimorph electrostrictive vibrator, 2: Center electrode, 3° 4: Ferromagnetic electrostrictive plate, 5, 6: Electrode, 7: Support member, 8: Terminal, 9 (9-1, 9-2): Displacement restraint member, 10 (
10-1, 1O-2): Permanent magnet. 11: Substrate, 11a: Vibrator support stand, 11b=Step part, 1
2: Cover case, 12a: Projection part.

Claims (3)

[Claims] (1) A bimorph electrostrictive vibrator consisting of a plurality of stacked ferroelectric electrostrictive plates each having electrodes on both sides.One end of the bimorph electrostrictive vibrator is fixed, and the other end is displaced by applying a voltage to the electrode. In the electrostrictive vibrator, at least one of the electrodes is made of a magnetic material, and comes into contact with the vicinity of the other end of the electrostrictive vibrator to restrain displacement of the other end so as to be able to swing within a breaking limit displacement range. A displacement restraint member is fixedly installed, a fixed magnetic body is fixedly installed near the displacement restraint member, and at least one of the electrode made of the magnetic body and the fixed magnetic body is magnetized, so that the distance between the electrode and the fixed magnetic body is A bimorph electrostrictive vibration device characterized in that an attractive force characteristic is generated in the bimorph electrostrictive vibration device. (2) The bimorph electrostrictive vibration device according to claim 1, wherein the electrode made of the magnetic material is a spring body. (3) A bimorph electrostrictive vibrating device according to claim 1 or 2, wherein the displacement restraining member is a fixed magnetic body.