JPS6315679A - Piezo-electric actuator - Google Patents

Abstract

PURPOSE: To enable favorable application to a small and thin device and to enable manufacture at low cost, by a method wherein a spring member and a piezo-electric element of bimorph structure are combined, and contact portion of the spring member is moved in elliptic motion. CONSTITUTION:A spring member 7 is provided on center portion with a contact portion 10 projecting to contact with a drive object, and on both ends with two legs 11, 12 bent in acute angle to cross to each other, and top end of the two legs 11, 12 is fixed to a stationary portion. Piezo-electric elements 13, 14 of bimorph structure are contacted with the two legs 11, 12 of the spring member 7, respectively. Voltage of prescribed polarity is selectively applied to these piezo-electric elements 13, 14, thereby the drive object is moved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric actuator for linearly moving or rotationally driving a driven object.

(Prior Art) In recent years, the need for various actuators in OA equipment, FAIII equipment, information equipment, etc. is expanding.In particular, in information equipment, there is a need to make the equipment smaller, lighter,
BACKGROUND ART With energy conservation, there is a demand for smaller and more efficient actuators for driving recording media and recording heads. However, conventionally, rotary or linear actuators using electromagnetic force have been used exclusively. These electromagnetic actuators have also been developed to be as thin and compact as possible by using sheet coils, for example. However, in these 1Efl type actuators, when the recording medium is, for example, a magnetic recording medium, there is a risk that magnetic noise may have an adverse effect on the recording medium.

Recently, research and development on piezoelectric actuators has been actively conducted as a new actuator to replace electromagnetic actuators. There are various types of piezoelectric actuators, but they generally have the following advantages over conventional electromagnetic actuators.

(1) High electrical-mechanical conversion efficiency and low energy consumption.

(2) It has a non-contact structure, does not trap dust, and is highly reliable.

(3) It is small and thin.

(4) There is no exchange of electromagnetic influences.

<5) Has high-speed response.

Therefore, taking advantage of these advantages, piezoelectric actuators are being considered for use as sounding bodies in watches, calculators, etc., for example.

FIGS. 8 and 9 are side views showing the configuration of a conventional piezoelectric actuator for linearly moving or rotationally driving an object to be driven, such as a recording medium.

In the device shown in FIG. 8, a vibrating piece 2 is attached to the tip of a piezoelectric vertical vibrator 1 at an angle of θ, and the above-mentioned camera element 1 is attached at an angle indicated by an arrow.
The driven object 3 is moved in the direction of arrow B by the movement of the tip of the vibrating element 2 when displaced in the direction.

In the device shown in FIG. 9, a piezoelectric slide sensor 5 is attached to the tip of a vertical piezoelectric vibrator 4, and the vibrator 4 is displaced in the direction of arrow C, and the sensor 5 is displaced as shown by the broken line. The force generated when the drive target 6 is moved in the direction of the arrow.

[Problem that the invention seeks to solve]

The piezoelectric actuator shown in FIGS. 8 and 9 is
Since both use piezoelectric elements as drive sources, some of the above-mentioned advantages are utilized. However, both have problems in terms of thinning.

In other words, in the case shown in Figs. 8 and 9, the driving force acting on the driven object is obtained by combining vertical imaging and lateral vibration, so if you try to increase the driving speed to a certain extent, , it becomes necessary to form the piezoelectric sensor into an FA layer structure. Otherwise, an element with high power and large dimensions, such as a Langevin oscillator, must be used.

Therefore, it is difficult to reduce the thickness.

Therefore, the present invention has all of the above-mentioned advantages (1) to (5), and is particularly suitable for application to small and thin devices.
Moreover, it is an object of the present invention to provide a piezoelectric actuator that can be manufactured at low cost.

[Means for solving problems]

In order to solve the above problems and achieve the objectives, the present invention has the following features:
It is characterized by the following measures: That is, the central part has a protruding contact part that contacts the driven object, and the two ends have two legs bent at an acute angle so as to cross each other, and the tips of the two legs are attached to the fixed part. A spring member is provided to be fixed to the spring member, and piezoelectric elements having a bimorph structure are bonded to each of the two legs of the spring member, and a voltage having a predetermined polarity is selectively applied to these piezoelectric elements. .

(Function) By taking such measures, the contact portion of the spring member performs elliptical motion along the contact surface with the driven object due to the combination of the spring member and the piezoelectric element having a bimorph structure. Therefore, the object to be driven that is welded to the contact portion is linearly moved or rotationally driven.

〔Example〕

FIGS. 1(a) and 1(b) are a perspective view and a front view showing the structure of a first embodiment of the present invention. In FIGS. 1(a) and 1(b), 7 is a spring member made of phosphor bronze, beryllian copper, or the like. This spring member 7 has a central part thereof,
It has a contact part 10 which is curved and protrudes so as to be in contact with the object to be driven, and has two legs 11 and 12 bent at acute angles at both ends thereof so as to intersect with each other. The tips of the bipods 11, 12 can be fixed to a fixed part. A piezoelectric element 13.14 having a bimorph structure is bonded to each of the two legs 11.12 using, for example, an epoxy adhesive. These piezoelectric elements 13.1
A grounding lead terminal 15 is attached to the negative leg 12 so that a voltage having a predetermined polarity can be selectively applied to the piezoelectric element 13. are the respective installations.

FIG. 2 is a diagram showing the structure of the piezoelectric elements 13 and 14 having the bimorph structure. The piezoelectric element 20 shown here is a pair of piezoelectric ceramic plates 21 and 22 bonded together. Note that a piezoelectric ceramic plate and a metal rotary plate may be bonded together. As shown in the figure, the piezoelectric ceramic plates 21 and 22 are polarized in the direction of the arrow, and when a voltage of a predetermined level is applied and has a predetermined polarity, the tip of the piezoelectric element 20 is displaced by ΔX as shown by the broken line. , the two legs 11.12 are displaced in a predetermined direction by the displacement force F. The displacement ΔX generated in the piezoelectric element 20 at this time is
Measure the length of the piezoelectric bimorph.

The thickness is t, and the electrostriction constant of piezoelectric ceramics is d3! .

When the applied voltage is V, Δx=3·ri2·d31·V/2t2. In addition, the deflection force F at the deflection end at this time is as follows, where Young's modulus is Eh and the width of the piezoelectric bimorph is W, F=3・Wt−d31・E h −V/8 ffi
becomes.

Next, the operation of the piezoelectric actuator of this embodiment configured as described above will be explained in FIGS. 3 and 4 (a), (b) (C
). Now, the bipod 11 of the spring member 7.
For the piezoelectric elements 13 and 14 respectively connected to 12,
Applied voltage v11 with a waveform as shown in FIG. and Vl2
Suppose that we apply each of them. Then, bipod 11.12
The displacement status of the spring member 7 changes sequentially as shown in FIG. 3(a).
(b) It operates as in (C). The operating state will be explained step by step below.

Condition (2) (Vl 1.0, Vl 2.-0) In this condition, equivalent displacement does not occur, so the condition shown by the solid line (3) in FIG. 4(a) is maintained.

State (vll...+V, V12...+V) In this state, each tip of the bipod 11.12 is displaced in the direction of the solid line arrow in FIG. 4(a), so the point P of the contact portion 10 shifts as indicated by the solid line arrow M, and shifts to the state indicated by the broken line ■ in FIG. 4(a). Therefore, if the object to be driven is in contact with the arcuate surface of the contact portion 10, the object to be driven will move linearly in the direction of arrow N.

State (2) (Vll...K V, V12...--) In this state, the displacement of the - leg 11 remains in the previous state, and only the other leg 12 is displaced in the opposite direction. Therefore, the contact portion 10 moves in a direction away from the driven object while deforming so that its radius of curvature becomes larger. Therefore, unless the object to be driven is provided to move in seven directions, the object to be driven will not be moved backward in the -N direction.

In this way, the state shifts to the state indicated by the broken line (■) in FIG. 4(b).

State (2) (Vll...O, Vl2...0) In this state, the bipods 11.12 are displaced to their initial positions. Therefore, the state shifts to the state indicated by the broken line ■ (=■) in FIG. 4(C).

Therefore, the contact portion 1o comes into contact with the object to be driven.

By repeating the following operations (1) to (2), the driven object will intermittently move in the direction of arrow N.

Also, contrary to the above, in Fig. 4(a), the bipod 11.1
2 as shown by the dashed arrow, then leave the monopod 12 as it is and displace the other leg 11 in two directions, then move the bipod 11.
12 in the -Z direction at the same time, the driven object can be moved in the opposite direction to the above case, that is, in the -N direction.

In this way, by sequentially and selectively applying voltages having predetermined polarities to the piezoelectric elements 13 and 14, two I! 1111.12 changes, and accordingly, the contact portion 10 causes an elliptical movement along the contact surface with the driven object. As a result, the object to be driven can be moved in a straight line.

FIG. 5 is a diagram showing a second embodiment of the present invention, and is a diagram showing an example in which the present piezoelectric actuator is implemented as an actuator for transferring a magnetic card. In the figure, 31 and 32 are housings, and the inside of the housing 31 has a sliding member 33 such as felt.
is the installation.

34 is a magnetic card, which can be slidably loaded on the sliding member. This piezoelectric actuator is configured such that the bipod 11 is in a state where its contact portion is in contact with the other side surface of the magnetic card 34.
．． 12 is screwed to the inner surface of the housing 32.

35 is a voltage application circuit box, which is fixed to the inner surface of the housing 32.

In this embodiment, by operating the piezoelectric actuator, the magnetic card 34 is slid in the direction shown by the arrow. The spring member of the second VFJ
11.12 is bonded to the upper surface side, but similarly to the first example, it may be attached to the lower surface side, or furthermore, it may be attached to both surfaces to increase the driving force.

FIG. 6 is a diagram showing a third embodiment of the present invention.

In this embodiment, a friction sliding member 4 is provided on the contact surface of the contact portion 1o.
This is an example of pasting 0. According to this embodiment, slipping is less likely to occur and the degree of transport traverse can be increased, and the generation of noise and damage to the driven object are less likely to occur.

FIG. 7 is a diagram showing a fourth embodiment of the present invention.

In this embodiment, a pair of piezoelectric actuators 51 are arranged so as to face both the front and back surfaces of a drive target 50 such as a magnetic card.
．． 52, so as to perform double-sided driving. According to this embodiment, there is an advantage that the driving force for the driven object 50 is large and stable.

Note that the present invention is not limited to the above embodiments,
Of course, various modifications can be made without departing from the spirit of the invention.

〔Effect of the invention〕

According to the present invention, the contact portion has a protruding contact portion in the center so as to be in contact with the driven object, and has two legs bent at an acute angle to intersect with each other at both ends, and the tips of the two legs A spring member is provided which is fixed to the fixed part, and a piezoelectric element having a bimorph structure is bonded to each of the two legs of the spring member,
Since a voltage having a predetermined polarity is selectively applied to these piezoelectric elements, it has all the advantages peculiar to the piezoelectric type that type II actuators do not have, and also has the advantages of the spring member and bimorph structure. In combination with a piezoelectric element, it is possible to provide a piezoelectric actuator that is suitable for application to small and thin devices and can be manufactured at low cost.

[Brief explanation of drawings]

1(a)(b) to 4(a)(t)>(C) are diagrams showing the first embodiment of the present invention, and FIG. 1(a)(b) is the overall configuration. 2 is a side view showing the configuration of a bimorph piezoelectric element, FIG. 3 is a diagram showing applied voltage waveforms, and FIGS. 4(a), (b), and (c) are explanations of operation. It is a diagram. FIG. 5 to FIG. 7 are the second to seventh embodiments of the present invention, respectively.
It is a figure showing a 4th example. FIG. 8 and FIG. 9 each show a side opening showing different conventional examples. 7... Spring member, 10... Contact portion, 11.12.
... Bipod, 13,14.20... Piezoelectric element with bimorph structure, 21.22... Piezoelectric ceramic plate. Applicant's agent Patent attorney Atsushi Tsuboi Figure 1 Fn Figure 2 Figure 5 LO Figure 6 Figure 7 Figure 9 Commissioner of the Patent Office Black 1) Akira M. 1. Indication of the case Japanese Patent Application No. 61-157286 2, Name of the invention Piezoelectric actuator 3, Person making the amendment Relationship to the case Patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent 3-chome, Kasumigaseki, Chiyoda-ku, Tokyo No. 7, Exit 2 B [Building 5, Voluntary amendment 6, Full text of detailed construction subject to amendment 7, Contents of amendment

Claims (1)

[Claims] It has a contact part that protrudes in the center so as to be in contact with the driven object, and has two legs bent at an acute angle so as to intersect with each other at both ends, and the tips of the two legs are fixed to the fixed part. A piezoelectric element having a bimorph structure joined to each of the two legs of the springy member, and voltage applying means for selectively applying a voltage having a predetermined polarity to the piezoelectric elements. A piezoelectric actuator characterized by: