JPH01235288A - Laminated type piezoelectric displacement element - Google Patents

Abstract

PURPOSE:To inhibit the lowering of the displacement of each bimorph element, and to extract a large quantity of displacement efficiently by connecting a plurality of the bimorph elements without constraining the displacement of the bimorph elements. CONSTITUTION:A first layer rectangular type bimorph element 11 is fixed by a fixture 21 at a central section, and coupled with a second iayer bimorph element 12, the direction of displacement of which is opposed and which is arranged oppositely, by U-shaped leaf springs 31, 32 functioning as electrodes combining shim materials. Each central section is combined by a fixture 22 in the element 12 and a third layer bimorph element 13. Consequently, a member in which the central sections of two bimorph elements are connected and unified mutually by the fixture is used as a fundamental element, the members are laminated at multistages, and maximum displacement sections in the adjacent fundamental elements are coupled mutually by the leaf springs for both-end support sections, thus inhibiting the lowering of the quantities of each element displaced at a time when the bimorph elements are formed in multistage structure. Accordingly, a laminated type piezoelectric displacement element having a large quantity of displacement can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a laminated piezoelectric displacement element having a multi-stage configuration of a plurality of bimorph piezoelectric elements.

(Conventional technology) Conventionally, actuators using piezoelectric effects have been small and lightweight, have low power consumption, low heat generation, do not generate magnetic fields and have little effect on other electronic components, and are voltage-driven, making them easy to control. It is used in various fields because it has many advantages such as ease of use.

As actuators that utilize such piezoelectric effects, transverse effect actuators represented by laminated longitudinal effect actuators, sliding effect actuators, and bimorph piezoelectric elements (hereinafter abbreviated as bimorph elements) have been put into practical use. Bimorph elements are often used when a relatively large amount of displacement is required.

As shown in Fig. 7, a bimorph element has a structure in which two piezoelectric elements with electrodes provided on both sides of the piezoelectric body are superimposed, and in this case, the piezoelectric body 1.2 has a polarization direction in the direction of the arrow in the figure.
In contrast, both side electrodes 3a.

When a negative potential is applied to 3c and a positive potential is applied to the sandwiching electrode 3b, the piezoelectric body 1.2 curves as shown by the dotted line in the figure. Further, when opposite potentials are applied to both side electrodes 3a, 3c and the sandwiching electrode 3b, the curves in the opposite direction.

Incidentally, although the amount of displacement of the bimorph element is larger than that of other piezoelectric actuators, there is naturally a limit value to the displacement when used alone. Therefore, if a larger amount of displacement is required,
A possible method is to increase the displacement by connecting a plurality of bimorph elements. However, in this method, since the displacement force of the bimorph element is small, the displacement is restricted depending on the connection conditions, and it is actually difficult to extract the displacement of each bimorph element efficiently.

(Problem to be Solved by the Invention) As described above, in a laminated piezoelectric displacement element in which bimorph elements are connected in multiple stages, there is a problem in that the displacement of each bimorph element is restricted in the multi-stage connection, and the overall amount of displacement is reduced. there were.

The present invention has been made in consideration of the above circumstances, and its purpose is to be able to suppress a decrease in displacement of each element in a multi-stage connection structure of bimorph elements, and to efficiently extract a large amount of displacement. It is an object of the present invention to provide a laminated piezoelectric displacement element that can be used.

[Structure of the Invention] (Means for Solving the Problems) The gist of the present invention is to connect a plurality of bimorph elements without restricting the displacement of the bimorph elements.

That is, the present invention provides a stacked piezoelectric displacement element formed by stacking a plurality of bimorphs in multiple stages, in which two bimorph elements arranged facing each other with a predetermined distance are connected to each other at the center by a fixing member to be integrated. The basic elements are stacked in multiple stages, and the maximum displacement parts of adjacent basic elements are connected by supporting members at both ends.

(Function) According to the present invention, since the maximum displacement parts of the basic element consisting of two bimorph elements are connected to each other, it is possible to suppress a decrease in the amount of displacement of each element when the bimorph elements are arranged in a multi-stage structure. Can be done. Therefore, it is possible to realize a laminated piezoelectric displacement element with a large amount of displacement.

(Example) Hereinafter, details of the present invention will be explained with reference to illustrated embodiments.

FIG. 1 is a perspective view showing a schematic configuration of a laminated piezoelectric displacement element according to an embodiment of the present invention. In the figure, reference numeral 11 denotes a first-layer strip-shaped bimorph element, and this bimorph element consists of two piezoelectric bodies, electrodes on both sides, sandwiching electrodes, etc., as shown in FIG. 7. The same applies to the bimorph elements in the second and subsequent layers. The first-layer strip-shaped bimorph element 11 is fixed at the center by a fixing jig 21, and the fixing jig 21 is fixed at a fixed end (not shown).

The bimorph element 11 is connected to a second-layer bimorph element 12, which is disposed opposite to each other with the direction of displacement reversed, by U-shaped leaf springs 31 and 32, which function as shims and electrodes. The second-layer bimorph element 12 and the third-layer bimorph element 13 are fixed at their central portions using a fixing jig 22.
are connected by

Further, the third layer bimorph element 13 and the fourth layer bimorph element 14 are connected by leaf springs 33 and 34 in the same way as the bimorph elements 11 and 12 are connected. moreover,
The fourth layer bimorph element 14 and the fifth layer bimorph element 15 are integrally connected by a fixing jig 23 in the same way as the bimorph elements 12 and 13 are connected. Note that the leaf spring 35 connected to the maximum displacement part of the fifth layer bimorph element 15 is integrated at the upper part, and the bimorph element 15
Tie both ends together.

By applying a voltage as shown in FIG. 2 in such a configuration, it is possible to obtain a displacement obtained by integrating the displacement amount of each bimorph as shown in the figure. FIG. 2(b) shows an initial state in which no voltage is applied. FIG. 2(a) shows the expanded state by applying a positive potential to the electrodes on both sides of each bimorph element and applying a negative potential to the sandwiching electrode sandwiched between the two piezoelectric bodies. FIG. 2(c) shows a state in which each bimorph element is shrunk by applying a negative potential to both side electrodes and a positive potential to the sandwiching electrodes. The difference between FIG. 2(a) and FIG. 2(C) is the maximum displacement amount.

Here, adjacent bimorph elements must have opposite displacement directions, but this displacement direction can be arbitrarily varied by changing the direction of the voltage applied to each bimorph element. Therefore, in reality, it is not necessary to consider the displacement directions of adjacent bimorph elements in advance, and it is sufficient to apply a voltage so that the adjacent bimorph elements have opposite displacements. In addition, the lengths of the fixing jig and leaf spring are shown in Figure 2(c).
The settings may be made so that adjacent bimorphs do not come into contact with each other in the contracted state shown in FIG.

Thus, according to this embodiment, it is possible to obtain a displacement amount by superimposing the displacements of the respective bimorph elements by configuring the bimorph elements in multiple stages. Moreover, since leaf springs are used as both end support members to connect both ends of the bimorph element,
Displacement is hardly restricted by the connection of bimorph elements. Therefore, the displacement of each bimorph element can be extracted efficiently, and the amount of displacement as a whole can be increased.

FIG. 3 is a perspective view showing the schematic structure of another embodiment of the present invention, and FIG. 4 is a schematic diagram showing the basic structure of the same embodiment. This embodiment uses a ring-shaped bimorph element instead of the strip-shaped bimorph element, and the basic structure is the same as that in FIG. 1.

The ring-shaped bimorph elements are arranged so that the displacement direction is reversed every other step, and the first layer bimorph element 41 has two diametrical sides (on one straight line) fixed by fixing jigs 51 and 5.
2 and is fixed to the fixed end 50 via these fixing jigs 51 and 52. The first and second layer bimorph elements 41 and 42 are connected at their maximum displacement portions by U-shaped leaf springs 61 and 62 that function as shims and electrodes. The maximum displacement portion refers to the two sides perpendicular to the two diametrical sides of the bimorph element to which the fixing jigs 51 and 52 are fixed.
It is the edge. By forming the leaf springs 61 and 62 into a U-shape, it is possible to connect them with little deformation in the vertical direction and without restricting rotational movement at the maximum displacement point. The second and third layer bimorph elements 42 and 43 are connected on two sides by fixing jigs 53 and 54, which are integral fixing jigs.

In addition, the third and fourth layer bimorph elements 43°44 are
Similar to the first and second layer bimorph elements 41°42,
They are connected by U-shaped leaf springs 63 and 64 at the maximum displacement portion. 4th and 5th layer bimorph element 44.4
5 are connected by fixing jigs 55 and 56, similar to the connection of the second and third layer bimorphs 42 and 43. The displacement to be utilized is obtained by connecting the maximum displacement parts of the fifth layer bimorph 45 with each other by a plate spring 65, and from the upper surface of this plate spring 65.

Here, the displacement posture of the ring-shaped bimorph element used in this example will be explained. FIG. 5 shows a specific structure of a ring-shaped bimorph element, in which two piezoelectric bodies 71 and 72 having polarization directions in the direction of the arrow in the figure are connected to an electrode 73b.
(Shim material and electrode as an electrode) are sandwiched and integrated.
Furthermore, electrodes 73a and 73 are provided on the other main surfaces of the piezoelectric bodies 71 and 72.
c (electrodes on both sides). When voltages of opposite polarity are applied to the electrodes on both sides and the clamping electrodes, the ring-shaped bimorph element is displaced as shown in FIG. When viewed from the side, the displacement posture appears to be the same as that of a strip-shaped bimorph element, but a ring-shaped bimorph element can obtain a larger displacement than a strip-shaped bimorph element depending on the shape of the ring.

When these ring-shaped bimorph elements are connected in multiple stages as shown in FIG. 3, displacement will occur as shown in FIG. 2, depending on the direction of the applied voltage.

The shape of the ring-shaped bimorph element is 50 m in outer diameter and 30 m in inner diameter. When the thickness of each piezoelectric body was 100 μm and the thickness of the leaf spring serving as a shim material and electrode was 50 μm, the displacement of the ring-shaped bimorph element alone was ~0.8 ms.

When this was made into a five-tier stacked structure using the configuration of this example, a displacement of 3.5a+m, which is approximately 4.4 times, could be obtained. When using the same configuration but replacing the U-shaped plate spring with a ceramic fixing jig, the amount of displacement was approximately zero even when stacking five layers.

In this way, this embodiment also provides the same effects as the previous embodiment. Furthermore, since the displacement of this embodiment is linear and the structure is hollow, it can be used as an actuator for autofocus by attaching a CCD to the displacement surface and connecting its wiring to another board through the hollow part. is also possible.

Note that the present invention is not limited to each of the embodiments described above. For example, the number of layers of bimorph elements is not limited to five, but may be two or more. In addition, when stacking two bimorph elements in multiple stages as basic elements,
The first and second layer bimorph elements or the second and third layer bimorph elements shown in FIG. 1 may be considered as basic elements. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, a plurality of bimorph elements can be connected without restricting the displacement of the bimorph elements, and a laminated layer that can obtain a large amount of displacement in multi-stage connection is realized. It becomes possible to realize a type piezoelectric displacement element. By stacking n stages, it is possible to obtain approximately n times the displacement of one bimorph element.

[Brief explanation of the drawing]

1 and 2 are for explaining a laminated piezoelectric displacement element according to an embodiment of the present invention. FIG. 1 is a perspective view showing a schematic configuration, FIG. 2 is a schematic diagram showing a displacement state, 3 to 6 are for explaining other embodiments of the present invention, in which FIG. 3 is a perspective view showing a schematic configuration, FIG. 4 is a schematic diagram showing a basic configuration, and FIG. 5 is a ring-shaped FIG. 6 is a cross-sectional view showing the specific structure of the bimorph element, FIG. 6 is a schematic diagram showing the displacement state, and FIG.
The figure is a cross-sectional view showing the structure and displacement state of a strip-shaped bimorph element, for explaining the conventional problems. 11, ~. 15... Strip-shaped bimorph element, 21, ~
, 23, 51. ~． 56... Fixing jig, 31, ~, 3
5,61. ~． 65...Plate spring (both end support members), 4
1. ~． 45...Ring-shaped bimorph element. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 3 Figure 4 Figure 7

Claims (6)

[Claims] (1) Comprising first and second bimorph piezoelectric elements arranged to face each other at a predetermined distance apart, and both end support members connecting both ends of these piezoelectric elements, the first and second bimorph piezoelectric elements are A laminated piezoelectric displacement element, characterized in that the piezoelectric elements are driven in opposite displacement directions, and central portions of the first and second piezoelectric elements are used as a fixed end and a displacement end, respectively. (2) The first and second bimorph piezoelectric elements are provided with first and second bimorph piezoelectric elements arranged facing each other at a predetermined distance apart, and a fixing member that connects and integrates the central parts of these piezoelectric elements, and
and a second piezoelectric element are driven in opposite displacement directions, and both ends of one piezoelectric element are used as fixed ends, and both ends of the other piezoelectric element are used as displacement ends. element. (3) A basic element is one in which the central parts of two bimorph piezoelectric elements arranged facing each other at a predetermined distance are connected to each other by a fixing member, and each basic element is stacked in multiple stages, and adjacent basic elements are stacked in multiple stages. A laminated piezoelectric displacement element characterized in that maximum displacement parts of the elements are connected by supporting members at both ends. (4) The laminated piezoelectric displacement element according to claim 1 or 3, wherein the both end support members are U-shaped springs. (5) Claim 1 characterized in that the both end support members have an integral structure with a shim material of a bimorph type piezoelectric element.
Or the laminated piezoelectric displacement element according to 3. (6) Two ring-shaped bimorph piezoelectric elements arranged facing each other at a predetermined distance are connected to each other by a fixing member at the parts located on any one straight line in the radial direction, and this is integrated into a basic element. 1. A laminated piezoelectric displacement element characterized in that each basic element is laminated in multiple stages, and the maximum displacement portions of adjacent basic elements are connected by supporting members at both ends.