JP2002084013A - Piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator wherein sufficient amount of displacement is generated, products having stable displacement characteristic and uniform quality can be simply manufactured, and development from a unimorph type to a bimorph type is enabled easily. SOLUTION: In this piezoelectric actuator, one end of an actuator main body in which a flexible substrate is stuck on a piezoelectric sheet formed in such a manner that displacement due to piezoelectric effect is generated in the longitudinal direction is retained by a fix end, and current flow control to the piezoelectric sheet is performed. Accordingly, displacement is generated at the other end of the actuator main body, and drives a load. The piezoelectric sheet has a structure wherein electrode material is bonded to both surfaces of a planar piezoelectric material of continuous length formed zigzag. In the electrode material, a first electrode and a second electrode are engaged with each other via a gap. The first electrode corresponds to one bending portion of a zigzag part in the piezoelectric material. The second electrode corresponds to the other bending portion of the zigzag part. The first electrode and the second electrode make a current flow with mutually different polarities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric actuator which drives a load by utilizing displacement of a medium caused by a piezoelectric effect.

[0002]

2. Description of the Related Art Recently, as a piezoelectric actuator capable of producing a relatively large amount of displacement, as shown in FIG. 1, each bending of a long plate-shaped piezoelectric sheet 1 'press-formed so as to meander in advance. A plurality of flexible base materials 2 ′, each of which is bent in advance with the same curvature, are adhered to the outside of the portion, and an end of the actuator body (displacement medium) 3 ′ is supported on a fixed side. A piezoelectric actuator has been developed by the same applicant as the present application to drive the load by causing the other end of the actuator main body 3 'to be displaced by controlling the energization of the piezoelectric sheet 1'. No. 11-38687).

As shown in FIGS. 2 and 3, the piezoelectric sheet 1 'is made of, for example, polyvinylidene fluoride (P).
A thin plate-shaped electrode material 5 ′ which is gold-plated on aluminum or copper is bonded to both surfaces of a long plate-shaped piezoelectric material 4 made of VDF).

In such a piezoelectric actuator, when a voltage is applied to the electrode material 5 'with a polarity in the direction in which the piezoelectric material 4 of the piezoelectric sheet 1' contracts, the outside of each curved portion of the piezoelectric sheet 1 '. When the piezoelectric material 4 shrinks, the degree of curvature of the piezoelectric sheet 1 'increases, and the actuator body 3' is displaced in a direction in which the actuator body 3 'shrinks by -δ as a whole. I do. The electrode material 5 ′ has a polarity in the direction in which the piezoelectric material 4 extends.
When the voltage is applied to the piezoelectric sheet 1, the degree of curvature of the piezoelectric sheet 1 'is reduced, and the actuator body 3' is displaced in a direction extending by + δ as a whole.

[0005]

The problem to be solved is that, when manufacturing a piezoelectric actuator, an adhesive is applied to the outside of each curved portion of a piezoelectric sheet which is previously meandered, and to the inside of a curved substrate. In this case, the application is performed one by one, and the work is complicated, the application of a plurality of base materials becomes uneven, and the displacement characteristics of the products vary. It is that you are.

In addition, if the actuator body is formed by attaching a plurality of pieces of base material to the outside of each curved portion of the piezoelectric sheet that has been meandered in advance, each curved portion of the piezoelectric sheet is formed of a so-called substrate. It is only a unimorph type with a piezoelectric sheet attached on one side, and it is difficult to use a bimorph type with a piezoelectric sheet attached to both sides of the substrate to increase the load driving force due to the displacement of the actuator body It is becoming.

[0007]

According to the present invention, one end of an actuator main body in which a flexible substrate is attached to a piezoelectric sheet formed so that displacement due to a piezoelectric effect occurs in a longitudinal direction is supported on a fixed side. Therefore, in a piezoelectric actuator in which a load is driven by causing a displacement at the other end of the actuator body by controlling the energization of the piezoelectric sheet, while securing a relatively large displacement amount,
A uniform product of stable quality with a stable displacement characteristic can be easily manufactured, and a unimorph type can be easily developed to a bimorph type.

Therefore, according to the present invention, the piezoelectric sheet is provided on both sides of a long plate-shaped piezoelectric material formed in a meandering manner, and first electrodes corresponding to one curved portion of the meandering in the piezoelectric material, respectively. And a second electrode portion respectively corresponding to the other curved portion of the meandering are formed by joining electrode materials combined so as to mesh with each other through a gap. And the electrodes are supplied with different polarities.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a piezoelectric actuator according to the present invention, as shown in FIG. 4, a long plate-shaped piezoelectric sheet 1 is press-molded in a meandering manner so that displacement due to the piezoelectric effect occurs in the longitudinal direction. The unimorph-type actuator body 3 is configured by laminating one flexible substrate 2 on one side. Then, by controlling the energization of the piezoelectric sheet 1 by the controller 6 with one end of the actuator body 3 supported on the fixed side, the load 7 is driven by causing a displacement at the other end of the actuator body 3. It is configured as follows.

As shown in FIG. 5, the piezoelectric sheet 1 has a structure in which a thin plate-like electrode material 5 is adhered to both sides of a long plate-like piezoelectric material 4. And the electrode material 5
However, as shown in FIG. 6, the first electrode portion 51 corresponding to one (right) curved portion when the piezoelectric material 4 is meandered, and the other (left) curved portion of the meandering portion. The second electrode portions 52 corresponding to the respective portions are combined so as to mesh with each other via the gap s, and the first electrode portion 51 and the second electrode portion 52 are controlled under the control of the controller 6. Energization is performed simultaneously with different polarities.

As the piezoelectric material 4, PVDF or the like, which is flexible and has a relatively large amount of expansion and contraction due to the piezoelectric effect, is used. The substrate 2 is made of, for example, polyethylene phthalate (PET), which is optimal as a material having appropriate flexibility while maintaining necessary elasticity. Substrate 2
May have a single-sheet structure or a laminated structure. As the electrode material 5, for example, a material obtained by plating aluminum or copper with gold is used.

In the piezoelectric actuator configured as described above, a voltage + E is applied between the first electrode portions 51 of the electrode member 5 with a polarity in a direction in which the piezoelectric sheet 1 contracts, and the voltage + E is applied between the second electrode portions 52. When a voltage of -E is applied with a polarity in the direction in which the piezoelectric sheet 1 expands, the piezoelectric sheet 1 contracts as shown in FIG. 7 in each of the right curved portions of the actuator body 3 shown in FIG. However, in this portion, the degree of curvature of the piezoelectric sheet 1 increases because the substrate 2 is outside the curvature. At the same time, the piezoelectric sheet 1 expands at each curved portion on the left side of the actuator body 3 as shown in FIG. 8, but since the substrate 2 is inside the curved portion at this portion, the piezoelectric sheet 1 The degree of the bend increases. Therefore, the entire actuator body 3 is displaced in a direction to contract by −δ.

The first electrode portion 51 of the electrode material 5
In the meantime, when a voltage -E having a polarity opposite to that described above is applied and a voltage + E having a polarity opposite to that described above is applied to the second electrode portion 52, the right curved portions of the actuator body 3 shown in FIG. In this case, as shown in FIG. 9, the piezoelectric sheet 1 is elongated, but in this portion, the degree of the curvature of the piezoelectric sheet 1 is reduced because the substrate 2 is outside the curvature. At the same time, the piezoelectric sheet 1 contracts as shown in FIG. 10 in each of the left curved portions of the actuator body 3, but since the substrate 2 is inside the curved portion in this portion, the piezoelectric sheet 1 The degree of curvature is reduced. Therefore, the entire actuator body 3 is displaced in the direction in which it extends by + δ.

However, by providing the substrate 2 to the piezoelectric sheet 1 to provide a certain degree of rigidity, and by forming the entire body into a curved shape, it is possible to generate a sufficient load driving force on the actuator body 3. become able to. Then, by changing the thickness of the substrate 2,
A desired load driving force characteristic can be provided.

Further, in the present invention, as shown in FIG. 11, two piezoelectric sheets 11 and 12 which are similarly press-formed so as to meander are formed on both sides of one flexible substrate 2. Thus, the bimorph-type actuator main body 8 can be easily configured.

FIG. 12 shows the characteristics of the measured data of the displacement when the magnitude of the applied voltage is changed using the bimorph-type actuator main body 8.

Here, the thickness of each piezoelectric material in the piezoelectric sheets 11 and 12 is 20 μm, the thickness of the substrate 2 is 50 μm,
The actuator body 8 having a radius of curvature of 6 mm and the number of curvatures of 5 is used, and the weight of the load 7 is 2 g and 10 g.
And In the figure, A shows the characteristics when the weight of the load 7 is 2 g, and B shows the characteristics when the weight of the load 7 is 10 g.

Further, the difference from the actually measured displacement when the weight of the load 7 was 2 g using the unimorph type actuator body 3 under the same conditions was about 1.5 times.

[0019]

As described above, in the piezoelectric actuator according to the present invention, both sides of a long plate-shaped piezoelectric material formed to meander in advance correspond to one of the meandering curved portions of the piezoelectric material. One side of a piezoelectric sheet having a structure in which an electrode material having one polarity and an electrode material having the other polarity respectively corresponding to the other curved portion of the meandering are bonded with an electrode material combined so as to mesh with a gap therebetween. Since the actuator body is formed by laminating a single flexible substrate, lamination of the piezoelectric sheet and the substrate can be performed easily and without variation. By producing a large amount of displacement, it is possible to easily manufacture a uniform product of uniform quality with stable displacement characteristics.

Further, according to the present invention, since the piezoelectric sheet is attached to one surface of the substrate, the other meandering piezoelectric sheet is similarly attached to the other surface of the substrate, so that the unimorph type There is an advantage that it can be easily developed from a piezoelectric actuator to a bimorph type piezoelectric actuator.

[Brief description of the drawings]

FIG. 1 is a front view showing a structure of an actuator main body in a conventional piezoelectric actuator.

FIG. 2 is a plan view of a piezoelectric sheet in the conventional actuator body.

FIG. 3 is a left side view of a piezoelectric sheet in the conventional actuator body.

FIG. 4 is a front view of a unimorph type piezoelectric actuator according to an embodiment of the present invention.

FIG. 5 is a plan view of the piezoelectric sheet in the example.

FIG. 6 is a left side view of the piezoelectric sheet in the embodiment.

FIG. 7 is a diagram showing a displacement state in a right curved portion when the actuator body contracts according to the embodiment.

FIG. 8 is a diagram showing a displacement state in a left curved portion when the actuator body contracts according to the embodiment.

FIG. 9 is a view showing a displacement state in a right curved portion when the actuator body according to the embodiment is extended.

FIG. 10 is a diagram showing a displacement state in a left curved portion when the actuator body according to the embodiment is extended.

FIG. 11 is a front view showing the structure of a bimorph-type actuator body according to the present invention.

FIG. 12 is a characteristic diagram based on measured data of a displacement amount with respect to an applied voltage when a bimorph-type actuator body according to the present invention is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric sheet 2 Substrate 3 Actuator main body 4 Piezoelectric material 5 Electrode material 6 Controller 7 Load 8 Actuator main body 11 Piezoelectric sheet 12 Piezoelectric sheet

Claims (3)

[Claims] An end of an actuator body in which a flexible substrate is bonded to a piezoelectric sheet formed so that displacement due to a piezoelectric effect occurs in a longitudinal direction is supported on a fixed side,
A piezoelectric actuator in which the load is driven by causing a displacement at the other end of the actuator body by controlling the power supply to the piezoelectric sheet, wherein the piezoelectric sheet has a long plate formed to meander. A first electrode portion corresponding to one curved portion of the meandering of the piezoelectric material and a second electrode portion respectively corresponding to the other curved portion of the meandering are formed on both sides of the piezoelectric material. A piezoelectric material in which the first electrode portion and the second electrode portion are simultaneously energized with different polarities from each other so as to be engaged with each other so as to be engaged with each other through the electrode. Actuator. 2. The piezoelectric actuator according to claim 1, wherein a piezoelectric sheet is attached to one surface of the substrate. 3. The piezoelectric actuator according to claim 1, wherein piezoelectric sheets are attached to both surfaces of the substrate.