JPS6372172A - Sheet-like electrostrictive laminated body - Google Patents

Abstract

PURPOSE:To facilitate the manufacture and to improve the mass-productivity by a method wherein, after the base material and internal electrodes of a sheet- like electrostrictive laminated body which can expand and contract in a mode of the piezoelectric constant d33 have been baked, a sheet-like rectangular substrate is formed and external electrodes are attached to the substrate so that grille-like electrodes can be formed. CONSTITUTION:At a sheet-like rectangular substrate 4, more than one internal electrodes 6a, 6b are installed across a rectangular piezoelectric ceramic base material 5, such as titanate, lead zirconate or the like, in such a way that one end of the electrodes is exposed alternately at one side and at the other side of the base material 5, and the base material 5 and the internal electrodes 6a, 6b are baked together. External electrodes 7a, 7b are installed at both sides of the rectangular substrate 4. Through this constitution, an exposed end of the internal electrode 6a is connected to the external electode 7a, and an exposed end of the internal electrode 6b is connected to the external electrode 7b. The electrodes 6a, 7a and the electrodes 6b, 7b are shaped like the teeth of a comb which engage with one another, and an electrostrictive layer 8 is formed between the internal electrodes 6a, 6b.

Description

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

<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.

That is, 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 d3.
When set to 1, it is expressed as δ=%(sentence/l)2・■・d 31 .

In addition, the displacement amount of an electrostrictive drive body using an electrostrictive element polarized in the length direction can be calculated by changing the piezoelectric constant d31 to the piezoelectric constant d33 in the previous equation, which is 8-'44 (1/l).
It is expressed as 2*V*dzz.

By the way, this piezoelectric constant d33 is the piezoelectric constant d:l+
It has a value 2 to 3 times that of From this, it is understood that an electrostrictive drive body with a larger displacement can be obtained by polarizing in the length direction and using nine electrostrictive elements.

Therefore, as disclosed in Japanese Patent Application Laid-open No. 81-2378, a pair of terminals are arranged facing 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. A method was proposed in which a voltage was applied and the direction of expansion and contraction matched the direction of polarization.

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

The present invention aims to eliminate the drawbacks of the conventional structure and provide a thin plate electrostrictive laminate that is easy to manufacture.

Means for Solving the Problems> The present invention provides a plurality of internal electrodes in a piezoelectric device base material, which cross the base material and have one ends exposed alternately on one side and the other side of the base. is arranged, further comprising a thin rectangular substrate formed by integrally firing the base material and internal electrodes, and external electrodes formed on both sides of the thin rectangular substrate, and between the adjacent internal electrodes. The electrostrictive layer is characterized in that it is polarized in alternate directions.

Effect〉 When an alternating voltage is applied to the external electrode layer of this electrostrictive laminate,
Each electrostrictive layer expands and contracts in the stacking direction based on the piezoelectric constant d ff:l. Then, at the free end (at the center in the case of peripheral holding), the amount of strain in each electrostrictive layer is superimposed, resulting in a large strain.

This electrostrictive laminate can constitute an electrostrictive drive body by adhering it to one side of a curved plate made of ceramic or the like, and the expansion and contraction of the electrostrictive laminate is inhibited on one side by this curved plate. , the telescopic action is converted into a bending action. The maximum displacement occurs at the free end.

In addition, when two electrostrictive laminates, one of which serves as a movable plate for the other, are attached via an insulating layer, when the electrostrictive element on the negative side is stretched, the electrostrictive a carcass on the other side By making an electrical connection such that it contracts, it will also produce a maximum displacement at its free end as it bends.

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

3 shows an electrostrictive drive body with a unimorph structure in which a thin plate electrostrictive laminate 1 of the same shape is adhered on a rectangular ceramic plate 2. Here, this thin plate electrostrictive laminate 1 has a thin plate shape. External electrodes 7a and 7b are arranged on both sides of a rectangular substrate 4.

The thin rectangular substrate 4 has a plurality of internal electrodes 6 across a rectangular piezoelectric ceramic base material 5 made of lead zirconate titanate or the like.
a, 6b are arranged alternately on one side and the other side of the base material 5 so that one end is exposed, and the base material 5 and the internal electrodes 6a,
It is fired together with 6b.

For the internal electrodes 6a, 6b, a material that can be fired integrally with the piezoelectric ceramic base material 5 is selected, and may be made of a silver-palladium alloy, molybdenum, manganese, platinum, etc. whose melting point is higher than the firing temperature.

External electrodes 7a are provided on both sides of the rectangular substrate 4.

7b, the exposed end of the internal electrode 6a is connected to the external electrode 7a, and the exposed end of the internal electrode 6b is connected to the external electrode 7b. form interdigitated comb-like electrodes, and an electrostrictive layer 8 is formed between each internal electrode 6&, 6b. This electrostrictive layer 8 is polarized in alternate directions by applying a DC voltage to the external electrodes 7a and 7b.

Thin electrostrictive laminate l and electrostrictive drive body 3 having the above configurations
is manufactured by the following means.

First step; (Fig. 2 A) A plurality of raw sheet-like electrostrictive layers 8 made of piezoelectric ceramic powder such as lead zirconate titanate are connected to an internal electrode 6a with one end exposed on one side surface and one end exposed on the other side. The laminate X is formed by stacking the internal electrodes 6b in one direction with the internal electrodes 6b exposed on the side surfaces alternately interposed. Each electrostrictive layer 8 has an internal electrode 6a,
The rectangular piezoelectric ceramic substrates 5 are continuous with each other in the areas without 6b.
This will constitute the following. For the internal electrodes 6a and 6b, the above-mentioned material that can be integrally fired is applied.

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

Third step; (Go to Figure 2) The thin plate-like laminate y is fired. At this time, each internal electrode 6a
, 6b are made of a material such as a silver-palladium alloy that has a melting point higher than the firing temperature, so they do not melt and can be fired.

Fourth step; (Figure 2 2) Polish the upper and lower surfaces of the thin plate-like laminate y.

Fifth step; (FIG. 2 E) External electrodes 7a and 7b are applied to both end surfaces of the thin plate-like laminate y, and heat-cured or heat-baked as required.

Sixth step; (Go to FIG. 2) A DC voltage is applied to the external electrodes 7a and 7b to polarize each electrostrictive layer 8, respectively. Thus, a thin electrostrictive laminate 1 is constructed.

Seventh step; (FIG. 2G) After cleaning the thin plate electrostrictive aM body 1, the ceramic plate 2
The surfaces are bonded together using adhesive.

Tea ceremony process; (Fig. 2 H) Lead wires 9a and 9b are soldered to external electrodes 7a and 7b.

In the fifth step of the manufacturing process, external electrodes 7a and 7b are applied to both end surfaces of the thin plate-like laminate y, but a conductive layer is previously formed on both sides of the laminate In addition to cutting and forming the thin plate-like laminate y in the process, external electrodes 7a and 7b may be provided on both sides of the laminate y.

Further, the slicing in the second step may be performed using a tool such as a diamond cutter after sintering the laminate X.
- Furthermore, the polishing in the fourth step is performed on the external electrode 7a in the fifth step.
, 7b or after the polarization in the sixth step.

The electrostrictive drive body 3 manufactured by the above process is shown in FIG.
Hold one end on the mounting part 10 like a mouth, and connect the lead wire 9a.
, 9b are connected to a DC power source via a switching mechanism. Then, as the voltage is applied, a curved displacement occurs at the free end.

The electrostrictive drive body 3 has a free length of 12.5 mm, the thickness of the thin electrostrictive laminate 1 is 85 m layer, the thickness of the ceramic plate 2 is 0.25 mm, and the shape is ia JE 0.9s+s. Apply W pressure from 0 to 30 m in 30 seconds.
The voltage was increased to 0V, maintained at this voltage level for 1 second, and then reduced to Ov for 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 8 Qpm at the maximum voltage of 300V.

In the above structure, a metal plate may be used instead of the ceramic plate 2. In this case, an insulating layer such as an adhesive layer is interposed between the thin electrostrictive laminate 1 and the ceramic plate 2. There is a need.

In addition, as shown in FIG. 5, two thin plate-like electrostrictive laminates la and l
Using adhesive, insulating layer 11.b such as an insulating plate. A bimorph-type electrostrictive drive body 10 is constructed by applying a circuit configuration in which the upper and lower thin plate-shaped electrostrictive laminates 1a and 1b have different expansion and contraction timings by surface-to-face contact via a metal substrate 12.

The electrostrictive drive body 10 having this configuration can also achieve a larger displacement than the conventional configuration.

Each of the electrostrictive drive bodies 3.10 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 for a VTR, and a fine movement control device.

<Effects of the Invention> As described above, the present invention provides a thin electrostrictive carcass l that expands and contracts according to the mode of the piezoelectric constant d33, and a base material 5 and an internal electrode 6.
A, 6b are integrally fired to form a thin rectangular substrate, on which external electrodes 7a, 7b are arranged, so that interdigital electrodes are formed and piezoelectric material is embedded in this. It has excellent effects such as being easy to manufacture and suitable for mass production.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a unimorph type electrostrictive drive body 3 to which the thin plate electrostrictive laminate l of the present invention is applied, and FIGS. Figure 3 A9 is a side view showing the operation of the electrostrictive drive body 3, and Figure 4 is a side view showing the operation of the electrostrictive drive body 3.
FIG. 5 is a partially cutaway perspective view of a bimorph type electrostrictive drive body 10 to which the thin plate electrostrictive laminate 1 of the present invention is applied. 1; Electrostrictive laminate 2; Ceramic plate 3; Electrostrictive body
5; Piezoelectric ceramic base material 6a, 6b; Internal electrodes 7a, 7b
; External electrode 8; Electrostrictive layer 10: Electrostrictive drive body Applicant NGK Spark Plug Co., Ltd. Figure 1 b Figure 3 Figure 4 Voltage (V) Figure 5 Procedural amendment (method) 1. Indication of the case Special Application No. 62-56158 2, Title of the invention Thin electrostrictive laminate 3, Relationship to the case of the person making the amendment Applicant address 14-18 Takatsuji-cho, Mizuho-ku, Nagoya Name (45)
4) NGK Spark Plug Co., Ltd. Representative: Tei Suzuki - 4, Agent: 460 Address: 3-11-11 Chiyoda, Naka-ku, Nagoya City ``Figure 2 I - 1'' means ``Figure 2 is'' I am corrected.

Claims (1)

[Scope of Claims] A plurality of internal electrodes are disposed within a piezoelectric ceramic base material, crossing the base material and having one end exposed alternately on one side and the other side of the base material, and further comprising: a piezoelectric ceramic base material; and an internal electrode are integrally fired, and external electrodes are formed on both sides of the thin rectangular substrate, and the electrostrictive layers between the adjacent internal electrodes are alternately different. A thin plate-like electrostrictive laminate characterized by being polarized in a direction.