JPS6372171A - Manufacture of electrostrictive driver - Google Patents

Abstract

PURPOSE:To facilitate the manufacture and to improve the mass-productivity by a method wherein an electrostrictive driver which is constructed to expand and contract in a mode of the piezoelectric constant d33 is formed by slicing a laminated body. CONSTITUTION:A laminated body x is formed in such a way that more than one raw sheet-like electrostrictive material layers 5 made of piezoelectric ceramic powder, such as titanate, lead zirconate or the like, are stacked up in one direction by alternately piling up an internal electrode layer 4a whose one end is exposed to one side and an internal electrode layer 4b whose one end is exposed to the other side. Then, this laminated body is sliced along the laminating direction so that a sheet-like laminated body y can be formed. Then, this sheet-like laminated body y is baked. After the surface and the back of the laminated body y have been polished, both edge faces of the sheet-like laminated body y are coated with external electrode layers 6a, 6b, and this assembly is then baked. Then, a DC voltage is applied to the external electrode layers 6a, 6b, and each electrostrictive layer 5 is polarized. After a layerlike electrostrictive device plate 3 obtained in this way has been washed, this plate is fixed to the surface of a ceramic plate 2 by an adhesive agent. Then, lead wires 7a, 7b are soldered to the external electrode layers 6a, 6b.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electrostrictive drive body that bends in one direction by applying a voltage and is applied as a drive source for various types of devices such as dot printers, parts feeders, and polarizing mirrors for laser beams. Regarding.

<Prior art> Electrostrictive actuators that use one or two electrostrictive elements and apply voltage to electrode layers formed on the upper and lower surfaces of the elements to cause a bending action at their free ends are called unimorphs or bimorphs. It is called and known.

Such an electrostrictive drive body is used in a cantilever supported or both end supported format, but it has been found that the amount of displacement varies greatly depending on the polarization direction of the electrostrictive element.

In other words, in the case of an electrostrictive drive body that uses an electrostrictive element polarized in the thickness direction and is supported on a cantilever, the displacement amount δ of the free end is determined by the free length, the total thickness t, the applied voltage V, and the piezoelectric constant d.
31, it is expressed as δ=%(vertical/1)·V-d31.

In addition, the displacement amount of an electrostrictive drive body using an electrostrictive element polarized in the length direction can be determined by changing the piezoelectric constant d ffl to a piezoelectric constant d :13 in the previous equation, and δ;%(i/1 )
It is expressed as eV*cl+:+.

By the way, this piezoelectric constant d33 is equal to 2 of the piezoelectric constant d31.
~3 times the value. From this, it is understood that an electrostrictive drive body with a larger displacement can be obtained by using an electrostrictive element polarized in the length direction.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 81-237E1, a pair of terminals are disposed opposite to each other, and the amplitude is increased by using the mode of piezoelectric constant d33. The interdigital electrodes are formed by protruding internal electrodes in an alternating manner, and the composite piezoelectric material is filled in the slits of the electrodes. Apply voltage, and the direction of expansion and contraction,
A method was proposed in which the polarization direction was made to match the polarization direction.

<Problems to be Solved by the Invention> By the way, the conventional method described above has the disadvantage of poor productivity because it requires forming interdigital electrodes with a complicated structure by means such as etching, and embedding the piezoelectric material. there were.

The present invention aims to eliminate the drawbacks of the conventional structure and provide a manufacturing method suitable for mass production of electrostrictive actuators that can efficiently perform bending operations.

Means for Solving the Problems> The present invention provides a method in which a plurality of electrostrictive material layers are alternately interposed between internal electrode layers having one end exposed to one side surface and internal electrode layers having one end exposed to the other side surface. forming a laminate by stacking the laminate in one direction, and slicing the laminate along the lamination direction to obtain a layered electrostrictive element plate; internal electrodes on both sides of the layered electrostrictive element plate; a step of providing an external electrode layer electrically connected to the exposed end of the layer; and a step of face-to-face bonding the layered electrostrictive element plate to a curved plate that converts its expansion and contraction action into a bending action. It is characterized by:

The above-mentioned electrostrictive materials include ordinary materials that produce an electrostrictive effect through polarization treatment, as well as high permittivity ceramic plates (for example, disclosed in Japanese Patent Publication No. 53-38440) that are in a paraelectric phase within the operating temperature range. Materials that do not require this can also be applied.

Effect> A large number of layered electrostrictive element plates can be obtained from the laminate by slicing the laminate along the lamination direction. Therefore, it is suitable for mass production.

In the layered electrostrictive element plate manufactured by such means, when an alternating voltage is applied to the external electrode layer, each electrostrictive material layer has a piezoelectric constant d.
33, it expands and contracts in the stacking direction. Then, at the free end (in the case of peripheral holding, the central part), the amount of strain in each electrostrictive material layer is superimposed, resulting in a large strain. Since a bending plate is attached to one surface of the layered electrostrictive element plate to inhibit expansion and contraction of the layered electrostrictive element plate and convert the expansion and contraction action into a bending action, the strain causes curving. and the free end (center part)
The maximum displacement will occur at .

In addition, when two laminar electrostrictive element plates, one of which serves as a movable plate for the other, are attached through an insulating layer, when the electrostrictive element on the negative side is stretched, the laminar electrostrictive element on the other side By making an electrical connection such that the plate contracts, it will also result in a maximum displacement at the free end (center) as it bends.

<Example> An embodiment of the invention will be described with reference to FIG.

The electrostrictive drive body 1 is a unimorph formed by pasting a layered electrostrictive element plate 3 of the same shape on a rectangular ceramic plate 2.

This layered electrostrictive element plate 3 has internal electrodes 1j 4 a,
A plurality of electrostrictive material layers 5 are laminated in one direction with the internal electrode layers 4b interposed therebetween, and each internal electrode layer 4a, 4b is alternately exposed on both side surfaces in a staggered manner, and the internal electrode layer 4a is exposed. An external electrode layer 6a is provided on the side end surface, and an external electrode layer 6b is provided on the exposed end surface of the internal electrode layer 4b.

The internal electrode layers 4a and 4b are formed of, for example, a silver-palladium alloy, and the external electrode layers 6a and 6b are formed of, for example, a silver coating.

The electrostrictive drive body 1 having the above structure is manufactured by the following method.

First step; (Fig. 2 A) A plurality of raw sheet-like electrostrictive material layers 5 made of piezoelectric ceramic powder such as titanium-ugly lead zirconate are coated with an internal electrode layer 4a with one end exposed on one side, and one end with an internal electrode layer 4a exposed on one side. The laminate X is formed by stacking them in one direction with internal electrode layers 4b exposed on the other side alternately interposed.

Second step: (Figure 2) The laminate X is sliced along the stacking direction to form a thin plate-like laminate y.

Third step; (Figure 2 C) The thin plate-like laminate y is fired.

Fourth step: (Figure 2 2) The upper and lower surfaces of the thin plate-like laminate y are polished.

Fifth step; (Figure 2 E) External electrode layers 6a are provided on both end surfaces of the thin plate-like laminate y.

6b is applied and heat-cured or heat-baked as necessary.

Sixth step; (Go to FIG. 2) A DC voltage is applied to the external electrode layers 6a and 6b to polarize each electrostrictive material layer 5, respectively. Thus, a single-layer electrostrictive element plate 3 is constructed.

Seventh step; (FIG. 2G) After cleaning the layered electrostrictive element plate 3, it is surface-bonded to the ceramic plate 2 using an adhesive.

Eighth step; (Fig. 2 H) Lead wires 7a and 7b are soldered to external electrodes @6a and 6b.

In the manufacturing process, external electrode layers 6a and 6b are applied to both end surfaces of the thin plate-like laminate y in the fifth step, but conductive layers are previously formed on both sides of the laminate X,
While cutting and forming the thin plate-like laminate y in the second step, external electrode layers 6a and 6b may be provided on both sides of the laminate y.

Further, the slicing in the second step may be performed after the laminate X is sintered using a tool such as a diamond cutter.

Furthermore, the polishing in the fourth step may be performed after the external electrode in the fifth step or after the polarization in the sixth step.

The electrostrictive drive body l manufactured by the above process is shown in FIG.
Hold one end in the mounting part 9 like a mouth.

A DC power source is connected to the lead wires 7a and 7b via a switching mechanism. Then, as the voltage is applied, a curved displacement occurs at the free end.

The electrostrictive drive body 1 has a free length of 12.5 mm, the layered electrostrictive element plate 3 has a thickness of 0.85 m, the ceramic plate 2 has a thickness of 0.25 m, and a total thickness of 0.9 layers. A voltage was applied on a schedule such that the voltage was increased from 0V to 300V in 30 seconds, this voltage level was maintained for 1 second, and the voltage was decreased to 0V in a further 30 seconds. Then, as a result of measuring the amount of displacement with respect to this voltage, as shown in FIG. 4, the amount of displacement was about 80 pm at the maximum voltage of 300V.

In addition, in the conventional device having the same structure as above except that a normal single piezoelectric ceramic plate was applied in place of the layered electrostrictive element plate, the power of 22.61 t, m at 300V was obtained. It can be theoretically predicted that the amount of displacement will be the same.

In other words, it was confirmed that in the above example, a displacement amount three times or more can be achieved compared to the conventional configuration.

In the above structure, a metal plate may be used instead of the ceramic plate 2. In this case, it is necessary to interpose an insulating layer such as an adhesive layer between the layered electrostrictive element plate 3. There is.

Also, as shown in Fig. 5, two layered electrostrictive element plates 3a and 3b
Using an adhesive, an insulating layer 11 such as an insulating plate, etc. The upper and lower layered electrostrictive element plates 3a are joined face-to-face via the metal substrate 12.
, 3b, the bimorph type electrostrictive drive body 10 is constructed by applying a circuit configuration in which the expansion and contraction timings of the parts 3b and 3b are different. The electrostrictive drive body 10 having this configuration can also achieve a larger displacement than the conventional configuration.

Each of the electrostrictive drive bodies 1 and 10 is used as a drive source that requires large torque, such as a dot printer, a parts feeder, a polarizing mirror for a laser beam, a magnetic head of a VTR, and a fine movement control device.

The electrostrictive material may be a piezoelectric composite material made by incorporating piezoelectric ceramic powder into an organic material such as synthetic rubber or synthetic resin, and instead of the ceramic plate 2, plastic,
A flexible material such as rubber may be applied. In the case of this configuration, the above-mentioned sintering step (third step)
does not require

Further, the electrostrictive drive body having this configuration is used as a drive source for speakers, headphones, etc., which requires a large amplitude and does not require a large torque.

<Effects of the Invention> As described above, in the present invention, since the electrostrictive drive body configured to expand and contract in a mode with a piezoelectric constant d33 is formed by slicing the end layer body X, manufacturing is easy and mass production is possible. It has excellent effects such as being suitable for

[Brief explanation of the drawing]

The accompanying drawings show embodiments of the present invention, and FIG. 1 is a perspective view of a unimorph type electrostrictive drive body 1 manufactured according to the present invention, and FIG.
Figures 1 to 1 are explanatory diagrams showing an example of the manufacturing process according to the present invention,
Figure 3 A9 is a side view showing the operation of the electrostrictive drive body 1;
The figure is a characteristic diagram of the product of the present invention, and FIG. 5 is a partially cutaway perspective view of a bimorph type electrostrictive drive body 10 manufactured according to the present invention. 1: Electrostrictive drive body 2; Ceramic plate 3; Layered electrostrictive element plates 4a, 4b; Internal electrode layer 5; Electrostrictive material layer 6a,
6b; External electrode layer lO; Electrostrictive drive body 1st Figure b Figure 3 Figure 4 Voltage (V) Figure 5 Procedural amendment (method) December 22, 1981 2, Title of invention Electrostrictive drive body Manufacturing method 3, relationship with the case of the person making the amendment Applicant Address 14-18 Takatsuji-cho, Mizuho-ku, Nagoya Name NGK SPARK PLUG CO., LTD. 3-11-11 Chiyoda 6, Subject of amendment Description 7, Contents of the amendment On page 12, line 16 of the specification, "Figure 2 I to I" is corrected to "Figure 2 is". . /=＼ Written amendment 1, Indication of the case Japanese Patent Application No. 1981-216912 2, Title of the invention Method of manufacturing an electrostrictive drive body 3, Relationship with the case of the person making the amendment Applicant's address Takatsuji-cho, Mizuho-ku, Nagoya City No. 14-18 Name NGK SPARK PLUG Co., Ltd. Representative: Bensutei-4, Agent 460 Address: 3-11-11-6, Chiyoda, Naka-ku, Nagoya, Reply to amendment Description 7, Contents of amendment 1) Details On page 3, line 19 of the book, it says "62% (sentence/1)・V'd31J".
(See/1) @V@d3. Correct it with J. 2) On page 4, line 4 of the specification, “62% (vert/1)・V-cl+:+J” is replaced with “62% (vertical/1)・V-cl+:+J”.
2% (view/1)・V@d3: Correct as vJ.

Claims (1)

[Claims] 1) A plurality of electrostrictive material layers are arranged in one direction by alternately interposing internal electrode layers with one end exposed on one side and internal electrode layers with one end exposed on the other side. forming a laminate by stacking the laminate, and slicing the laminate along the lamination direction to obtain a layered electrostrictive element plate; and a step of surface-bonding the layered electrostrictive element plate to a curved plate that converts its expansion and contraction action into a bending action. A method for manufacturing an electrostrictive drive body. 2) A patent characterized in that external electrode layers are provided on both sides of a layered electrostrictive element plate by forming conductive layers on both sides of the laminate and then slicing the laminate. A method for manufacturing an electrostrictive drive body according to claim 1. 3) After slicing the laminate to form a layered electrostrictive element plate, external electrode layers are formed on both sides of the layered electrostrictive element plate. A method for manufacturing an electrostrictive drive body. 4) The method of manufacturing an electrostrictive drive body according to claim 1, wherein the electrostrictive material layer is a piezoelectric ceramic material. 5) The method for manufacturing an electrostrictive drive body according to claim 1, wherein the electrostrictive material layer is a composite piezoelectric material. 6) The method for manufacturing an electrostrictive drive body according to claim 1, wherein the bending plate is a non-electrostrictive plate such as a ceramic plate or a metal plate. 7) The electrostrictive drive body according to claim 1, wherein the bending plate is another layered electrostrictive element plate whose expansion and contraction timing is opposite to that of the layered electrostrictive element plate. Production method.