JPS58196076A - Electrostrictive effect element - Google Patents

Abstract

PURPOSE:To obtain an element of large amount of displacement by a method wherein a part of the outer periphery of internal electrodes is formed into a structure of overlapping with the outer periphery of the section of an electrostrictive effect element, and the area is reduced more than that of the section. CONSTITUTION:Electrostrictive materials 21 and platinum internal electrodes 22 are laminated alternately, resulting in the electrostrictive effect element. The outer peripheral shape of each internal electrode 22 is equal to the sectional shape of the electrostrictive element. Each internal electrode has a part or more without the electrode 22 inside its outer periphery, in order to reduce the area of each internal electrode 22 more than the sectional shape. Next, each electrode 22 exposed on the side surface of the element is connected by lead wires 23 at intervals of a layer from the outside, and thus electrodes A and B are taken out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an electrostrictive element. An electrostrictive element is a transducer that converts electrical energy into mechanical energy by using the electrostrictive effect of a solid. In terms of odor bodies, electrodes such as metal films are formed on opposing surfaces of a solid that has a large electrostrictive effect, and the strain in the solid that occurs when a potential difference is applied between the electrodes is utilized. Since the strain that occurs in the direction parallel to the electric field (longitudinal effect strain) is generally larger than the strain that occurs in the perpendicular direction (transverse effect strain), the energy conversion efficiency is higher when the former is used. Further, the magnitude of strain is related to the electric field strength, and the greater the electric field strength, the greater the generated strain.

With the electrostrictive bare hand that utilizes the transverse effect, it is possible to obtain a displacement proportional to the dimension in the direction perpendicular to the electric field even with a constant applied voltage. However, in an electrostrictive element that utilizes a longitudinal effect with high energy conversion efficiency, when the externally applied voltage is kept constant and the dimension in the direction in which strain occurs increases, the electric field strength decreases, so the amount of displacement does not increase. Therefore, in order to obtain a large amount of displacement in this case, it is necessary to increase the applied voltage so that the electric field strength does not decrease. However, increasing the voltage requires a large and expensive power supply, which also increases the risk of handling. Furthermore, since the IC used in the control circuit for driving the transducer has a low breakdown voltage, it is not possible to use a very high voltage.

In order to improve the above drawbacks, a multilayer chip capacitor moat structure has been proposed. This structure is shown in Figure 1111 (a)
, shown in (b). In FIG. 1(a), internal electrodes 2 are formed at regular intervals inside the electrostrictive material 1, and every other electrode is connected to an external electrode 3. The spacing between the internal electrodes can be reduced to about several tens of microns using normal chip capacitor technology. If this structure is adopted, the distance between the electrodes becomes narrower, so an electrostrictive effect element using the longitudinal effect that can be driven at a low voltage can be realized.

By the way, as is clear from FIG. 1(b), which is a perspective view seen from the stacking direction, in this structure, the overlapping area of the internal electrodes (
The central rectangular portion) is small compared to the cross-sectional area of the element. Therefore, basically, the overlapping part of the internal electrodes deforms in response to the electric field, but the other parts do not, so the amount of displacement of the entire element does not correspond to the inherent strain of the material and is quite large. It has the disadvantage of being smaller. Furthermore, if a large alarm voltage is applied to generate a large strain, stress will be concentrated at the boundary between the deformed part and the non-deformed part, resulting in mechanical destruction of the element.

An object of the present invention is to provide an electrostrictive effect element that improves the above-mentioned drawbacks. The present invention provides an electrostrictive element in which materials exhibiting an electrostrictive effect and internal electrodes are alternately laminated, in which each internal electrode has a planar area smaller than the area of a cross section perpendicular to the lamination direction of the electrostrictive element. , and at least a part of the outer periphery of each internal electrode overlaps with the outer periphery of the cross section of the front distribution strain effect element, and each internal electrode is electrically connected every other layer from the outside of this element. It is characterized by Since the electrostrictive effect element of the present invention can increase the overlapping area of the internal electrodes, it is possible to achieve a larger amount of displacement than an element with a conventional structure, and at the same time, the strength against destruction is increased.

Next, the present invention will be explained in detail according to examples.

Example 1 Magnesium lead niobate Pb (Mg5(Nbq)
Os and lead titanate PbTi0. The effect of the electrostrictive effect element of the present invention was investigated using a ceramic material in which a solid solution was formed in a molar ratio of 9:1. This material is well known to exhibit large electrostrictive effects.

A slurry was prepared by mixing the prefired powder of this material, an organic binder, and an organic S mixture. This slurry was cast onto a film to a thickness of several 100 microns using a doctor blade method to produce a green sheet. After drying the axillary sheet, peeling it off from the Mylar film, and cutting it into the desired shape,
Platinum paste was printed on one side, several lθ sheets were laminated and crimped, and cut into predetermined dimensions.
It was fired at a temperature of 00°C.

Figures 2 (a) and (b) show the external appearance and internal electrode shape of an electrostrictive effect element having the structure of the present invention, in which the vertical and horizontal dimensions are a = 3 mm, and the length is l = 10 m. It has a rectangular parallelepiped structure in which electrostrictive material 21 and platinum internal electrodes 22 are alternately laminated. The spacing between the internal electrodes is 250 microns.

Further, in this embodiment, the outer peripheral shape of each internal electrode is equal to the cross-sectional shape of this electrostrictive effect element. In this case, in order to make the area of each internal electrode smaller than the area of the cross section perpendicular to the stacking direction of the element, each internal electrode has one or more parts inside its outer periphery where the electrode is not formed. . In this embodiment, each internal electrode has 16 such portions. The number, shape, and position of these parts can be changed at any time. In addition, in the example, the area of each internal electrode is 95 cm, 85%, and 7% of the cross-sectional area of the electrostrictive element.
An electrostrictive effect element having internal electrodes of 0Ls and 3s was fabricated. Next, each internal electrode exposed on the side of the element was electrically connected to every other layer by attaching lead wires from the outside, and two electrode terminals A and B were taken out.

For comparison, a conventional multilayer chip capacitor-type electrostrictive effect element shown in FIG. 1, which has the same external dimensions but a different electrode structure, was also prototyped at the same time. The overlapping area of the electrodes is 84 times the cross-sectional area of the device.

Apply a DC voltage between electrode terminals A and B of the element to measure the length of the element! The amount of directional displacement was measured for the device of the present invention and the conventional device. The results are shown in Figure 3.

In the figure, ■, ■, and ■ are related to the device of the present invention;
This is the case of 0-. As is clear from the figure, the electrostrictive element of the present invention has a larger displacement amount for the same applied voltage than the conventional element.

Sou 1 Man 1 Regarding the sample used in Example 1, a sinusoidal pulse voltage with a maximum voltage of 250 V and a pulse width of 1 ma was repeatedly and continuously applied to measure the maximum displacement amount and life. 4th result
As shown in the figure. The numbers in the figure correspond to the sample numbers of Example 1. As is clear from the figure, the maximum displacement of the conventional element is 1.
It was mechanically destroyed by applying pulses approximately 25,000 times at a diameter of 3 microns. - All of the devices of the invention had a maximum displacement of 1.3 microns or more, and did not break even after 100 million repeated voltage hole pulse applications.

As is clear from the above examples, it is clear that the electrostrictive effect element of the present invention is superior in displacement and life compared to conventional multilayer chip capacitor type elements.

Figure 1 is a structural diagram of a conventional multilayer chip capacitor type electrostrictive effect element.

FIG. 1(a) is a sectional view. FIG. 1(b) is a perspective view from the stacking direction.

FIG. 2 is a structural diagram of the electrostrictive effect element of the present invention.

FIG. 2(a) is a side view. FIG. 2(b) is a diagram showing the shape of the internal electrodes.

FIG. 3 is a diagram showing the relationship between displacement and applied voltage for the device of the present invention and the conventional device.

FIG. 4 is a diagram showing the relationship between maximum displacement and life when pulse voltage is repeatedly applied to the device of the present invention and the conventional device.

In each figure, 1.21 is an electrostrictive material, 2°n is an internal electrode, 3 is an outer St pole, and 3 is a lead wire.

Figure 1 Figure 2

Claims (1)

[Claims] In an electrostrictive element in which materials exhibiting an electrostrictive effect and internal electrodes are alternately laminated, each internal electrode has a planar area smaller than the area of a cross section perpendicular to the stacking direction of the electrostrictive element, and At least a part of the outer periphery of the internal electrode overlaps with the outer periphery of the cross section of the electrostrictive element, and each internal electrode is connected every other layer from the outside of the element. effect element.