JPH03225975A - Laminated piezoelectric actuator element - Google Patents

Abstract

PURPOSE:To enhance reliability and repetition durability by a method wherein a continuous insulator whose length is nearly the same as the length of its side face and whose width is a definite rate or lower of the width of its side face is formed and external electrodes which are connected electrically, at every other layer, to comb- shaped internal electrodes whose tip parts at comb teeth are exposed on the side face are formed on the insulator. CONSTITUTION:A continuous insulator whose width is 80% or lower of the width of its side face is used. Parts where only sheetlike piezoelectric ceramic materials 1 have been laminated and parts where the piezoelectric ceramic materials 1 and internal electrodes 2 are alternated are laminated collectively by using a high-pressure press; after that, this laminated body is baked to obtain a sintered body. External electrodes 4 whose shape is comb-shaped on one side face are situated in such a way that their comb-shaped tip parts at comb teeth come into contact with, at every one layer, end parts of the internal electrodes 2 which are exposed at the side face and come into contact with an external electrode 6 for soldering use; other comb-shaped parts are formed by a printing method in such a way that they are situated on an insulator 3. A lead wire 5 is soldered to the external electrode 6 for soldering use to obtain a piezoelectric actuator element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laminated piezoelectric actuator element, and particularly to the structure of an external electrode.

[Conventional technology]

3 and 4 are a cross-sectional view and a perspective view showing the structure of a conventional laminated piezoelectric actuator element.

In a conventional multilayer piezoelectric actuator element, piezoelectric ceramic materials 1 and internal electrodes 2 are alternately laminated, and one end surface of the internal electrodes 2 exposed on opposing sides of the element is covered with glass insulation every other layer on the opposing sides. After attaching the body 3 by electrophoresis, screen printing, etc., and insulating it by firing, an Ag paste is applied to connect one of the internal electrodes that is not insulated on the opposing sides, and the internal electrode 2 and insulator 3. The external electrode 4 constitutes two comb-shaped electrodes, a voltage is applied between the two comb-shaped electrodes, the piezoelectric ceramic material 1 between the internal electrodes is deformed, and displacement is taken out as an actuator.

[Problem to be solved by the invention]

In the conventional piezoelectric actuator element described above, the internal mold 8ii2 exposed on the side surface is insulated layer by layer with an insulator 3, but when electrophoresis is used as the insulation method, the insulator 3 is applied to the internal electrode to be insulated. Although it is easy to deposit the insulator 3 reliably, if the insulator 3 adheres to the internal electrode 2 and the amount of adhesion increases, the insulator 3 becomes a resistance, making it difficult to form a thicker insulator 3. In addition, when using the screen printing method, it is necessary to cover the internal electrode 2 with the insulator 3 over the entire width of the side surface, but since the internal electrode 2 may be curved during firing, in order to prevent the internal electrode 2 from being exposed, If the width of the insulator 3 is increased, the insulator 3 will also adhere to the internal electrodes 2 where it should not be attached, making it impossible to obtain electrical continuity, so there is a drawback that the width cannot be increased. In addition, since glass is used as an insulator in both methods, repeated application of voltage between internal electrodes causes strain on the glass, causing fatigue breakdown and loss of insulation, resulting in electrical discharge. There are drawbacks.

An object of the present invention is to provide a laminated piezoelectric actuator element that allows the material and thickness of the insulator to be freely selected and has high reliability and repeated durability.

[Means to solve the problem]

In the laminated piezoelectric actuator element of the present invention, the length in the direction in which the piezoelectric ceramic material and the internal electrode formed on a pair of opposing side surfaces of the laminated sintered body are laminated is approximately the same as the length of the side surface, and the width is It is formed by electrically connecting every other layer a continuous insulator with a width of 80% or less of the width of the side surface and an internal electrode having a comb shape with the tips of the comb teeth exposed on the side surface. The structure is characterized by having an external electrode.

〔Example〕

Next, the present invention will be explained with reference to the drawings. FIG. 1 is a side view of one embodiment of the present invention.

A portion in which only sheet-shaped piezoelectric ceramic materials 1 are laminated and a portion in which piezoelectric ceramic materials 1 and internal electrodes 2 are alternately laminated are integrally laminated using a high-pressure press, and then the laminated body is fired to obtain a sintered body.

Next, the sintered body is cut perpendicularly to the stacking direction to cut out a sintered body of desired dimensions. A silver paste is printed on a portion of the cut out sintered body on opposite sides where only the piezoelectric ceramic material 2 is laminated, and is fired to form an external electrode 6 for a solder elbow.

Next, on the side surface of the cut out sintered body on which the external electrode 6 for the solder elbow was formed, an insulator 3 made of a glass epoxy plate having a thickness of 0.3 t, a length almost the same as the side surface, and a width 3 mm smaller than the side surface is attached. Glue it to the side using epoxy adhesive.

Next, an external electrode 4 having a comb-shaped shape on one side is brought into contact with the end of the internal electrode 2 whose comb-shaped tips are exposed on the side at every other layer, and is attached to the external electrode 6 for the solder elbow. The other part of the comb shape is formed by a printing method so as to be in contact with the insulator 3.

Next, an external electrode 4 is similarly formed on the other side surface with a rigid shape, but in this case, the external electrode 4 is made to contact the end surface of the internal electrode 2 that is not in contact with the external electrode 4 on the opposite side surface. . In this case, the current flowing through one layer of internal electrodes is small, so the connection between the external electrode 4 and internal electrode is 0.5 to 1 mm.
is sufficient, so the alignment accuracy does not need to be as high as in conventional screen printing methods.

Next, the lead wire 5 is soldered to the solder elbow external electrode 6 to obtain a piezoelectric actuator element.

FIG. 2 is a side view of Embodiment 2 of the present invention. The shape of the insulator is made into a comb shape like the external electrode 4, and the position of the tip of the comb teeth is shifted by one layer from the tip of the comb teeth of the external electrode 4. Further, by using a liquid insulator as the material for the insulator 3, it is possible to form the insulator 3 in a complicated shape, and the insulator 3 can be formed by a printing method.

In this embodiment, since the insulator 3 is also comb-shaped, the printing position of the external electrode 4 is misaligned, preventing connection with the internal electrode that should not be connected, and the insulator 3 can be formed using the printing method. It has the advantage of being inexpensive.

〔Effect of the invention〕

As explained above, the present invention forms continuous insulators on opposing side surfaces of a piezoelectric actuator element, the length of which is approximately the same as the length of the side surfaces, and the width of which is 80% or less of the width of the side surfaces;
By forming external electrodes on this insulator that are electrically connected every other layer to internal electrodes that are comb-shaped and exposed on the tips or sides of the comb teeth, the material and thickness of the insulator can be changed freely. This makes it possible to provide piezoelectric actuator elements with high reliability and repeated durability.

[Brief explanation of drawings]

FIG. 1 is a side view of a piezoelectric actuator element according to an embodiment of the present invention, and FIG. 2 is a side view showing a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of a conventional piezoelectric actuator element, and FIG. 4 is a side view of FIG. 3. 1... Piezoelectric ceramic material, 2... Internal electrode, 3...
Insulator, 4... External electrode, 5. Lead wire, 6... Soldered dirty external electrode.

Claims (1)

[Claims] A laminated sintered body in which piezoelectric ceramic materials and internal electrodes are alternately laminated, and a pair of opposing sides of the internal electrodes exposed on the side surfaces of the laminated sintered body, one end of each internal electrode is staggered. In a piezoelectric actuator element in which the ends of the other insulated and non-insulated internal electrodes are electrically connected to the external electrodes provided on the opposing sides, The length in the direction in which the piezoelectric ceramic material and the internal electrode are laminated is almost the same as the length of the side surface of the laminated sintered body,
Formed by electrically connecting every other layer to a continuous insulator whose width is 80% or less of the width of the side surface and an internal electrode having a comb shape with the tips of the comb teeth exposed on the side surface on the insulator. 1. A piezoelectric actuator element, characterized in that it has an external electrode.