JP2002252384A - Piezoelectric ceramic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator whose electrical insulation between internal electrodes is enhanced, since lowering of a breakdown voltage between the internal electrodes is seen, when the internal electrode is exposed in the piezoelectric actuator sealed in a closed case. SOLUTION: The piezoelectric actuator is encapsulated in the closed case and its insulation breakdown voltage performance between the internal electrodes is improved by sticking a silicon material to the edge face of an element wherein the internal electrode is exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor for generating a voltage by applying pressure and a structure of a laminated piezoelectric actuator for generating a displacement or a force by applying a voltage.

[0002]

2. Description of the Related Art As a conventional piezoelectric actuator which is not enclosed in a sealed case, one described in Japanese Patent Application Laid-Open No. 2000-270568 is known. In the case where the internal electrodes 2 of the laminated piezoelectric ceramic are sealed in a sealed case, a resin is applied in an exposed state or in order to prevent electrode deformation during assembly.

[0003]

The prior art has a disadvantage that when the internal electrodes 2 of the laminated piezoelectric ceramic are exposed, dielectric breakdown occurs between the laminations of the internal electrodes 2. In addition, in the case where the epoxy resin is applied, a void is generated between the layer of the applied material and the base material, and a dielectric breakdown occurs between internal electrodes in a space formed by the void.

[0004] Therefore, an object of the present invention is to deposit silicon as an insulating material for preventing the withstand voltage and dielectric breakdown of both the exposed internal electrode 2 and the piezoelectric ceramic layer 1 to reduce the withstand voltage and the insulation resistance. It is not to be.

[0005]

Means for Solving the Problems A silicon material is attached to and covers a part or the whole of the internal electrode 2 on the exposed surface of the internal electrode 2 of the laminated piezoelectric ceramic.

[0006]

According to the present invention, the space between the layered electrodes of the adjacent internal electrodes 2 sandwiching the piezoelectric ceramic 1 of the laminated piezoelectric ceramic is covered with an electrically insulating material, so that the internal electrodes 2 are exposed to the gas in the closed case. By not being exposed and applying a low-viscosity silicon material, voids are not generated inside the silicon material, and the discharge through the gas between the internal electrodes is suppressed, and the silicon material, which is an insulating material, discharges. To prevent this, it is possible to improve the withstand voltage and the insulation resistance.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a view showing a laminated piezoelectric ceramic according to the present embodiment.
a piezoelectric ceramic sheet on which d-type internal electrodes 2 are printed;
Piezoelectric ceramic sheets on which the internal electrodes 2 are not printed are laminated, then integrated by hot pressing, and then fired. Further, in the fired body that has been subjected to the firing treatment, the outer shape processing is performed by machining, and the insulator 3 and the external electrode 4 are formed so that the internal electrodes 2 become counter electrodes every other layer. In the processing of the exposed surface of the internal electrode 2, after cutting with a diamond cutter, lapping of the cut surface is performed.

FIG. 3 shows an enlarged cross section AA of the laminated piezoelectric ceramic of FIG. 1 with a silicon material adhered thereto. The piezoelectric ceramic layer 1 and the internal electrode 2 are attached to the exposed surface of the internal electrode 2 so that both the piezoelectric ceramic layer 1 and the internal electrode 2 are covered with a silicon material. Silicon materials to be deposited are widely used as electronically high insulating materials for electronic components, and can form a layered film of 1 micron or more by dipping or spray coating.

FIG. 2 shows a form in which the laminated piezoelectric ceramic to which the above-mentioned silicon material is adhered is incorporated in a sealed case 7, and a lead wire 8 for electrically connecting the external electrode 4 to the outside of the sealed case is provided. It is attached.

As another embodiment, it is possible to obtain the same effect as that obtained by partially or entirely filling a sealed case with a silicon material, covering the periphery of the laminated piezoelectric ceramic with the silicon material, and attaching the piezoelectric material to the surface. I can do it.

[Brief description of the drawings]

FIG. 1 is a view showing a laminated piezoelectric ceramic.

FIG. 2 is a view showing a piezoelectric actuator in a sealed case.

FIG. 3 is a diagram showing a cross section of a laminated piezoelectric ceramic to which silicon is attached.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric ceramic layer 2 Internal electrode layer 3 Insulating layer 4 External electrode 5 Stacked piezoelectric ceramics 6 Silicon material 7 Sealed case 8 Lead wire

Claims (2)

[Claims] 1. A laminate in which three or more piezoelectric ceramic layers and two or more internal electrode layers are laminated, and an insulator is provided such that every other internal electrode is a counter electrode on the side surface of the laminate. In a piezoelectric actuator in which a part of the piezoelectric ceramic is used as an insulator layer without forming a layer or part of the internal electrode, and a multilayer piezoelectric ceramic with external electrodes formed on it is enclosed in a closed case, A piezoelectric actuator, wherein an insulating material is attached to part or all of an internal electrode exposed on a surface of a ceramic. 2. The piezoelectric actuator according to claim 1, wherein silicon is used as an insulating material.