JPH10190080A - Multilayer piezo-electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable repair easy even when a junction part, etc., of a piezo-electric substrate, an electrode and a lead breaks by containing a multilayer piezo-electric body contained and formed inside an inner-packaging case in a sheath case wherein an output electrode connected to an external lead in contact with an electrode terminal is formed. SOLUTION: A multilayer piezo-electric body is contained in a sheath case 8. The case 8 is constituted of an inner case 8a and an outer case 8b. A lead-out electrode 7 is formed inside the case 8. The lead-out electrode 7 comprises a contact part 7a wherein an electrode terminal of a multilayer body piezo-electric body is disposed in opposite contact therewith, a lead junction part 7b whereto a lead 9 is joined and an extraction part 7c connecting the contact part 7a and the lead junction part 7b. Thereby, repair is possible even if breakage occurs in a part such as a junction part of a piezo-electric substrate and an electrode or a connection part of the lead 9 to be connected to an external circuit. If it is impossible, the part can be repaired by exchanging each member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric element and a method of manufacturing the same, and more particularly to a laminated piezoelectric element used for a precision positioning device such as an optical device, a driving element for preventing vibration, and the like.

[0002]

2. Description of the Related Art Conventionally, there has been a laminated piezoelectric element in which an electrode plate is interposed between piezoelectric plates having electrode layers formed on the front and back surfaces. In such a laminated piezoelectric element, a voltage is applied from an electrode plate to a piezoelectric plate to extend the piezoelectric element by several to several tens of μm by a reverse piezoelectric effect, and is used as a driving force source such as an actuator.

[0003] In such a laminated piezoelectric element, various characteristics have been devised because the characteristics after lamination change greatly depending on the method of joining the piezoelectric plates, and the characteristic variation between elements becomes large. For example, there is a method in which a piezoelectric plate and an electrode layer are formed by firing simultaneously. In the method of forming the piezoelectric plate and the electrode layer by simultaneous firing, it is relatively easy to form the piezoelectric plate with a small thickness, and the applied electric field can be increased. (ZrTi) O ₃
It is necessary to use a noble metal such as Pd or Pt as an electrode material which is co-fired with a piezoelectric material made of ceramics such as above, and there has been a problem that the cost increases as the number of layers increases.

In Japanese Patent Application Laid-Open No. 4-370877, as shown in FIGS. 3 and 4, a plurality of piezoelectric plates 21 each having an electrode layer 22 made of silver (Ag) or the like are laminated on the front and back surfaces. An electrode plate 23 made of stainless steel or the like is arranged between the plates 21, and connection pieces 24 bent in the laminating direction of the piezoelectric plates 21 from the electrode plate 23 are provided so as to protrude alternately in different directions for each layer, The connection pieces 24 projecting in the same direction are overlapped in the vertical direction and connected by spot welding or the like, and a comb-shaped insulating spacer 25 made of synthetic resin is provided in a gap between the connection piece 24 and the outer peripheral portion of the piezoelectric plate 21.
Is inserted, and this is accommodated in a heat-shrinkable insulating tube 26. In the case of forming the electrode layer 22 on the front and back surfaces of the piezoelectric plate 21, this laminated piezoelectric element is formed by applying silver paste by, for example, a screen printing method and baking at a temperature of 500 to 550 ° C. A side plate 29 is welded to the bent piece 24, and lead wires 27 and 28 are soldered to the side plate 29. Via these lead wires 27 and 28, it is connected to an external circuit.

[0005]

However, in this conventional laminated piezoelectric actuator, the bent pieces 24 protruding from the piezoelectric plate 21 are connected to each other by welding, and the lead wires 27 and 28 are connected. Therefore, the joint between the piezoelectric plate 21 and the bent piece 24 and the bent piece 24 and the lead wire 2
There is a problem that repair is extremely difficult when the joints 7 and 28 are damaged.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and solves the problem that repair is difficult when the joints between the piezoelectric plate, the electrodes, and the lead wires are damaged. It is an object of the present invention to provide a laminated piezoelectric actuator as described above.

[0007]

In order to achieve the above object, in the laminated piezoelectric actuator according to the present invention, the internal electrodes are provided for each layer on the side of a piezoelectric plate having internal electrodes formed on the front and back surfaces. Provide alternately connected connection electrodes, provide electrode terminals connected to the connection electrodes at both ends of the piezoelectric plate in the laminating direction, and place the piezoelectric plate in the inner case so that a part of the electrode terminals is exposed. To form a laminated piezoelectric body,
This laminated piezoelectric body was housed in an outer case in which a take-out electrode was formed in contact with the electrode terminal and connected to an external lead wire at a desired position.

[0008]

With the above-described configuration, even if the bonding portion of the piezoelectric plate or the electrode or the connection portion of the lead wire for connecting to the external circuit is damaged, it can be repaired individually and repaired. If it is not possible, each member can be replaced and repaired.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 are views showing an embodiment of a laminated piezoelectric actuator according to the present invention, wherein 1 is a piezoelectric plate, 2 is an internal electrode, 3 is a connection electrode, 4 is an electrode terminal, 5
Is an interior case, 6 is a laminated piezoelectric body, 7 is an extraction electrode, 8 is an exterior case, and 9 is a lead wire.

As the piezoelectric material constituting the piezoelectric plate 1, for example, a piezoelectric ceramic material mainly containing lead zirconate titanate (Pb (ZrTi) O ₃ ) is used. As the piezoelectric material, as the piezoelectric strain constant d ₃₃ it is high is preferable. However, the present invention is not limited to this, and any ceramics having piezoelectricity may be used. This piezoelectric plate 1 is small in size and applies a high voltage.
It is formed to a thickness of about 0.2 to 0.6 mm. It is desirable that the flatness of the piezoelectric plate 1 be as small as possible.
That is, when a high voltage is applied in a state where a plurality of the piezoelectric plates 1 are stacked and a high compressive stress is applied in the axial direction, the piezoelectric plate 1 may be cracked, and the performance as an actuator is secured. This is because it may not be possible. In addition, an inactive piezoelectric plate 1a that has not been subjected to polarization processing is disposed at both ends of the piezoelectric plate 1 in the stacking direction.

A plurality of the piezoelectric plates 1 are laminated, and on the front and back surfaces of the piezoelectric plate 1, internal electrodes 2 which become positive and negative when a voltage is applied are formed. This internal electrode 2 is formed by baking silver or other metal paste at about 500 ° C.
It is formed to a thickness of about 15 μm. Further, a metal such as silver may be formed by a thin film technique such as evaporation or sputtering. The internal electrodes 2 are formed so as to alternately protrude in the opposite direction for each layer of the piezoelectric plate 1. The side that does not protrude from the piezoelectric plate 1 is formed so as to be recessed inside the piezoelectric plate 1 in order to prevent a short circuit or the like.

The internal electrode 2 is connected to a connection electrode 3 formed on the side of the laminated body of the piezoelectric plate 1 at the protruding portion. The connection electrode 3 preferably has elasticity such as conductive resin or conductive rubber. Further, a conductive metal tape may be used. The connection electrode 3 may be connected to the internal electrode 2 alternately for each layer, and is not limited to being formed on the side surface of the laminated body of the piezoelectric plate 1 and may be formed on the inner surface of an interior case 5 described later. Good.

Electrode terminals 4 connected to the connection electrodes 3 are provided on both upper and lower ends of the stacked piezoelectric plates 1. The electrode terminal 4 is made of silver, brass, copper, stainless steel, or the like, and has a convex cross section. One of the upper and lower ends of the electrode terminals 4 serves as a positive electrode terminal,
The other is an electrode terminal for the negative electrode.

The laminated piezoelectric plate 1 and electrode terminals 4
It is fixed by the interior case 5. The interior case 5 is made of a highly insulating resin such as a heat-shrinkable tube made of Teflon. That is, a plurality of, for example, about 100 sheets are stacked so that the internal electrodes 2 of the plurality of piezoelectric plates 1 abut against each other, and are heated and pressed while applying pressure in the stacking direction, and fixed in the interior case 5. When the piezoelectric plate 2 is fixed by the interior case 5 as described above, the processing can be performed at a lower temperature than in the case of glass bonding or the like, the heat history during the manufacturing process is reduced, and the reliability of the laminate is improved. The interior case 5 is not limited to the case where the entire outer peripheral surface of the laminated piezoelectric plates 1 is covered, but may be partially covered. A plurality of the piezoelectric plates 1 are laminated and fixed by an interior case 5 to form a laminated piezoelectric body 6.

The laminated piezoelectric body 6 is housed in an outer case 8. The outer case 8 includes an inner case 8a and an outer case 8b.
And made of a voltage-resistant resin such as an epoxy resin or a polyimide resin. In this outer case 8,
An extraction electrode 7 is formed. The extraction electrode 7 includes a contact portion 7a provided so as to be held in contact with the electrode terminal 4 of the laminated piezoelectric body 6, a lead wire joining portion 7b to which the lead wire 9 is joined, and It is composed of a lead portion 7c connecting the portion 7a and the lead wire joining portion 7b.

The contact portion 7a is formed, for example, by forming a conductive film on one surface of a conductive metal plate or a resin plate. The lead wire connecting portion 7b is formed of a conductive metal plate or the like bent in an L-shape, and is disposed at an intersection between a side surface and a bottom surface between the inner case 8a and the outer case 8b. A through hole is formed in the outer case 8b where the lead wire joint 7b is located so that the lead wire joint 7b is exposed. The lead portion 7c is formed by forming a conductive metal plate or a conductive film on the inner surface of the outer case 8a or the outer surface of the inner case 8b,
It is formed so as to be bent integrally with the abutting portion 7a, and is disposed so as to be located between the outer case 8a and the inner case 8b. The lead wire 9 is joined to the exposed portion of the lead wire joint 7b by spot welding, soldering, or the like.

In such a laminated piezoelectric actuator, the lead wire joint 7 is provided between the outer case 8a and the inner case 8b.
b, the drawer 7c, and the lower contact portion 7a are respectively arranged at predetermined positions to assemble the outer case 8 and join the lead wire 9 to the lead wire joining portion 7b. The body 6 is dropped and the upper contact portion 7
It is assembled by bringing a into contact with the upper terminal electrode 4 and fixing it. Further, the contact portion 7a from the lead wire 9,
A voltage is applied to the piezoelectric plate 1 via the electrode terminals 4, the connection electrodes 3, and the internal electrodes 2. Further, the movable cap 11 is brought into contact with the upper part of the contact part 7a via the O-ring 10 by external pressure. The movable cap 11 is formed of an insulating metal, an epoxy resin, a polyimide resin, or the like. When the cap 11 is driven, it acts as an actuator.

[0018]

As described above, according to the multilayer piezoelectric actuator of the present invention, the internal electrodes are alternately connected to each side of the piezoelectric plate having the internal electrodes formed on the front and back surfaces. A connection electrode is provided, and electrode terminals connected to the connection electrode are provided at both ends of the piezoelectric plate in the stacking direction, and the piezoelectric plate is housed in an inner case so that a part of the electrode terminal is exposed and stacked. Since a piezoelectric body was formed, and the laminated piezoelectric body was housed in an outer case formed with an extraction electrode connected to an external lead wire at a desired position in contact with the electrode terminal,
Even if the joints of the piezoelectric plates or electrodes, or the connecting parts of the lead wires for connecting to external circuits, etc., are damaged, they can be individually repaired.If repair is not possible, replace each member. Can be repaired.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a laminated piezoelectric actuator according to the present invention.

FIG. 2 is a view showing a laminated piezoelectric body portion of the laminated piezoelectric actuator according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional laminated piezoelectric actuator.

FIG. 4 is a perspective view showing a conventional laminated piezoelectric actuator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric plate, 2 ... Internal electrode, 3 ... Connection electrode, 4 ... Electrode terminal, 5 ... Interior case, 6 ...
Laminated piezoelectric body, 7 ... extraction electrode, 8 ... outer case,
9 Lead wire, 10 O-ring, 11 Movable cap

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Go Setoguchi 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima

Claims (1)

[Claims] 1. A connecting electrode in which said internal electrodes are alternately connected for each layer is provided on a side portion of a piezoelectric plate having internal electrodes formed on the front and back surfaces, and said connecting electrodes are provided on both ends of said piezoelectric plate in a stacking direction. An electrode terminal connected to an electrode is provided, the piezoelectric plate is housed in an inner case so that a part of the electrode terminal is exposed to form a laminated piezoelectric body, and the laminated piezoelectric body is brought into contact with the electrode terminal. A multilayer piezoelectric actuator housed in an outer case having an extraction electrode connected to an external lead wire at a desired position.