JPH053352A - Laminated piezo-electric actuator and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the occurrence of stress concentration when a laminated piezo-electric actuator is driven. CONSTITUTION:Protruding sections 3a and 3b are provided on the side face of a laminated piezo-electric actuator and gaps formed between internal electrodes 2a and 2b and external electrodes 4a and 4b are filled up with an insulating substance 5. Therefore, a laminated piezo-electric actuator in which the insulating substance 5 is hardly stripped off from the piezo-electric ceramic plates and occurrence of stress concentration can be prevented when this actuator is driven and which can be easily manufactured can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric actuator in which piezoelectric ceramic plates made of thin plate piezoelectric ceramics and internal electrodes are alternately laminated, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, for example, as shown in FIG.
As shown in (a) and (b), a film or thin plate-shaped piezoelectric ceramic plate (1) made of a piezoelectric material and an internal electrode (2)
a) and (2b) are alternately laminated to form the internal electrode (2
a) and (2b) are external electrodes (4a) and (4b), respectively.
Or the piezoelectric ceramic plates (1) and the internal electrodes (2a) and (2b) are alternately laminated as shown in FIG. To form an insulating material layer (5), and the other side surface is coated with the insulating material at the end of the internal electrode where the insulating material is not applied on the one side surface. To form a laminated body, and a laminated piezoelectric actuator in which a conductive material is applied as external electrodes (4a) and (4b) to both side surfaces of the laminated body (Japanese Patent Publication No. 63-17).
354) or internal electrodes (2a), (2b) formed on the surface of the piezoelectric ceramic plate (1) as shown in FIG.
Electrodeless portions (6) are formed on the peripheral edge of the piezoelectric ceramic plates (1) so that the electrodeless portions (6) overlap with each other, and then the external electrodes (6) are formed on the side surfaces of the laminated body. 4a) and 4b) are formed so as to alternately contact the internal electrodes (2a), (2b) and the electrodeless portion (6) (JP-A-58-196075). Alternatively, as shown in FIG. 7, notches (7) are alternately formed on the side end surface of the piezoelectric ceramic plate (1), and the notches (7) are filled with an insulating material to form an insulating material layer ( 5) and thereafter the external electrodes (4a) and (4b) are formed on both side surfaces of the piezoelectric ceramic plate (1) (JP-A-60-1).
Various structures and manufacturing methods have been proposed such as 54581).

[0003]

However, the above-mentioned piezoelectric actuator has the following problems. That is, the piezoelectric actuator in FIG. 4 has internal electrodes (2a), (2b) as shown in FIG.
Area is smaller than the area on the laminated surface side of the piezoelectric ceramic plate (1), and no internal electrode exists in the peripheral portion. Therefore, when a voltage is applied between the external electrodes (4a) and (4b), the electric field strength becomes strong only at the overlapping portions of the internal electrodes (2a) and (2b), and the electric field strength at the peripheral portions becomes weak. For this reason, the peripheral portion of the piezoelectric actuator hardly displaces even when a voltage is applied, and thus the displacement amount of the entire piezoelectric actuator becomes small. Furthermore, stress concentration occurs at the boundary between the displaced portion and the non-displaced portion, and the piezoelectric ceramic plate (1) may be mechanically broken when a high voltage is applied, repeated application, or long-term application. It was

On the other hand, the piezoelectric actuator shown in FIG. 5 can solve the drawbacks of the piezoelectric actuator shown in FIG. 4, but since the insulating material layer (5) does not displace when a voltage is applied, it does not function as the insulating material layer (5). Stress concentration occurs between the piezoelectric ceramic plate (1) and the insulating material layer (5) when a high voltage is applied, repeated application or long-term application.
There are problems such as cracks and peeling off from the piezoelectric ceramic plate (1) and high precision in providing the insulating material layer (5).

In the case of the piezoelectric actuator as shown in FIG. 6, since no electric field is applied to the portion of the piezoelectric ceramic plate (1) which overlaps with the electrodeless portion (6) like the piezoelectric actuator shown in FIG. It becomes a part. Therefore, there is a problem that stress concentration occurs at the boundary between the non-displacement portion and the displacement portion of the piezoelectric ceramic plate (1), which causes destruction.

Further, in the laminated piezoelectric actuator shown in FIG. 7, notches (7) have to be formed in each piezoelectric ceramic plate (1), which requires time and effort for manufacture and requires high precision. .

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 forms a laminate by laminating a plurality of piezoelectric ceramic plates through internal electrodes formed on one plane thereof. In the laminated piezoelectric actuator in which the internal electrodes are alternately connected to the external electrodes formed on the opposite side surfaces of the laminate, the piezoelectric ceramic plates are laminated while being staggered in one direction. The protruding portions of the piezoelectric ceramic plate are formed on the opposite side surfaces of the body, the insulating material layers are formed in the gaps formed between the protruding portions, and the protruding portions are formed. By forming the external electrodes on the opposite side surfaces of the laminate, the internal electrodes are alternately connected to the opposing external electrodes. It is obtained by an actuator.

According to a second aspect of the invention, the insulating material layer of the first aspect has elasticity.

According to a third aspect of the present invention, internal electrodes are formed on one surface of each of a plurality of piezoelectric ceramic plates, and the plurality of piezoelectric ceramic plates are laminated via the internal electrodes to form a laminate. Then, in the method for manufacturing a laminated piezoelectric actuator in which the internal electrodes are alternately connected to the external electrodes formed on the opposite side surfaces of the laminated body, the piezoelectric ceramic plates are laminated while being staggered in one direction. The protrusions of the piezoelectric ceramic plate are formed on the opposite side surfaces of the stack, and the insulating material layers are formed in the gaps formed between the protrusions to form the protrusions. By forming the external electrodes on opposite side surfaces of the laminated body, the internal electrodes are crossed with the external electrodes facing each other. It is possible as the manufacturing method of the laminated piezoelectric actuator to be connected to.

[0010]

According to the laminated piezoelectric actuator and the method of manufacturing the same of the present invention, a plurality of piezoelectric ceramic plates are laminated while being staggered in one direction so as to form an protruding portion and an insulating material between the protruding portions. Since the layer is provided, the adhesion between the insulating substance and the piezoelectric ceramic plate is increased, and the insulating substance is less likely to peel off or crack.
Further, in the piezoelectric actuator having the above-described structure, strain is absorbed by the insulating material layer provided with the gap in the protruding portion, so stress concentration is relieved, the piezoelectric ceramic plate is hard to break, and the piezoelectric ceramic plate expands and contracts. When you do, the movement is not bound. Further, since the insulating material is embedded in the gap between the protruding portions, the insulating material layer will not be lost even if stress concentrates on the insulating material layer and cracks or the like enter. Moreover, since the protruding portion ensures a sufficient distance between the internal electrode and the external electrode, reliable insulation can be achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIGS.

1 to 3 are views showing a structure and a manufacturing method of a laminated piezoelectric actuator according to an embodiment of the present invention. As shown in these figures, a ceramic green sheet in which a piezoelectric ceramic powder such as PZT or PLZT, an organic solvent, and an organic binder are mixed is fired to form a piezoelectric ceramic plate (1) cut into a predetermined thickness. Apply silver paste or the like to the piezoelectric ceramic plate (1),
Internal electrodes (2a) and (2b) are provided. The piezoelectric ceramic plates (1) thus formed are stacked in a staggered manner in one direction as shown in FIG. 2 to form a stacked body of piezoelectric ceramic plates. At this time, the piezoelectric ceramic plate (1) is preferably displaced by 3% to 5% of the area of the plane perpendicular to the stacking direction of the piezoelectric ceramics. Next, the laminated body is subjected to thermocompression bonding, and the displaced protrusions (3a), (3) of the laminated body of the piezoelectric ceramic plate (1) obtained by this
External electrodes (4a) and (4b) are formed on a surface having the surface b) by a conductive material such as silver paste. Further, the protruding portions (3a) and (3b) and the external electrode (4a),
The inner electrode (2a), (2b) and the outer electrode (4a), (4b) are preferably filled with an insulating material such as resin or glass, which has elasticity and has a high insulating property, in the gap with the (4b). An insulating material layer (5) is formed to insulate the material. At this time, the external electrodes (4a), (4b) and the insulating material layer (5) may be provided over the entire width of the side surface having the protrusions (3a), (3b) as shown in the figure, or with a certain width. It may be provided.

The laminated piezoelectric actuator (10) thus formed is connected to the internal electrodes (2a) every other layer in one of the external electrodes (4a), and the other external electrode (4b) is connected to the one of the external electrodes (4b). Is connected to the internal electrode (2b) that is not connected to the external electrode (4a), and the electrodes are electrically formed in parallel. The laminated piezoelectric actuator (10) is subjected to a polarization process (poling) by applying a polarization voltage of about 120 V, and the polarization directions are aligned so that the piezoelectric ceramic plates (1) are displaced in the stacking direction when a voltage is applied. To do so. This time,
Since it is possible to align the polarization directions more reliably by applying a higher voltage, in order to obtain a large displacement and a large torque, the internal electrode (2
It is necessary to ensure the insulation between a) and (2b) and the external electrodes (4a) and (4b).

The laminated piezoelectric actuator is
Although it is formed by using a pre-fired piezoelectric ceramic plate, a thin plate-shaped green sheet is used as the internal electrode (2
After laminating via a) and (2b), firing may be performed.

In the laminated piezoelectric actuator manufactured as described above, since the insulating material layer (5) is embedded in the groove portions formed by the protruding portions (3a) and (3b), the insulation is prevented. The adhesiveness of the material layer (5) becomes high, and the insulating material layer (5) becomes difficult to peel off. In addition, the internal electrodes (2a) and (2b) and the external electrodes (4a),
No cuts or the like are required to insulate from (4b), and the piezoelectric ceramic plates (1) only need to be staggered to be laminated, so that they can be manufactured very easily. On the other hand, when driving the piezoelectric actuator, the protruding portions (3a) and (3b)
The strain is absorbed by the insulating material layer provided therebetween, so that the stress concentration is relieved, the piezoelectric ceramic plate (1) is hard to break, and the movement is not restricted. Furthermore, since the protrusions (3a) and (3b) provide reliable insulation,
Relatively high driving voltage and polarization voltage are applied.

[0016]

As described above, in the laminated piezoelectric actuator obtained according to the present invention, the piezoelectric ceramic plates are shifted in one direction to provide the protruding portions, and the insulating material is provided in the gap provided between the protruding portions. Since the layer is provided, the adhesiveness of the insulating material layer is good and the insulating material layer does not easily peel off.

Moreover, since the strain is absorbed by the insulating material layer provided between the protruding portions, the piezoelectric ceramic plate is hard to break and its movement is not restricted.

Further, since the protruding portion can secure a sufficient distance between the external electrode and the internal electrode, reliable insulation can be achieved, and a relatively high driving voltage or polarization voltage can be applied as compared with the conventional laminated piezoelectric ceramics. You will get it.

Further, according to the method of manufacturing the laminated piezoelectric actuator of the present invention, since the notch for insulating the internal electrode and the external electrode is not required, the labor can be saved.

[Brief description of drawings]

FIG. 1 is a front view of a laminated piezoelectric actuator according to an embodiment of the present invention.

2 is a perspective view showing a method for laminating piezoelectric ceramic plates of the laminated piezoelectric actuator shown in FIG.

FIG. 3 is a plan view of the laminated piezoelectric actuator shown in FIG.

FIG. 4 is a front view and a perspective view of a conventional laminated piezoelectric actuator.

FIG. 5 is a front view of a conventional laminated piezoelectric actuator.

FIG. 6 is a perspective view of a conventional laminated piezoelectric actuator.

FIG. 7 is a front view of a conventional laminated piezoelectric actuator.

[Explanation of symbols]

1 Piezoelectric ceramic plate 2a, 2b internal electrode 3a, 3b protruding portion 4a, 4b external electrodes 5 Insulating material layer

Claims (3)

[Claims] 1. A laminated body is formed by laminating a plurality of piezoelectric ceramic plates with an internal electrode formed on one surface thereof interposed therebetween,
In a laminated piezoelectric actuator in which the internal electrodes are alternately connected to external electrodes formed on opposite side surfaces of the laminated body, the laminated body is formed by staggering the piezoelectric ceramic plates in one direction and laminating the piezoelectric ceramic plates. Protruding portions of the piezoelectric ceramic plate are formed on opposite side surfaces of the piezoelectric ceramic plate, and insulating material layers are formed in the gaps formed between the protruding portions to fill the gaps. A laminated piezoelectric actuator characterized in that the external electrodes are formed respectively on opposite side surfaces of a body so that the internal electrodes are alternately connected to the external electrodes facing each other. 2. The laminated piezoelectric actuator according to claim 1, wherein the insulating material layer includes an insulating material having elasticity. 3. An internal electrode is formed on one surface of each of a plurality of piezoelectric ceramic plates, and a plurality of the piezoelectric ceramic plates are laminated via the internal electrodes to form a laminated body. In a method for manufacturing a laminated piezoelectric actuator in which the internal electrodes are alternately connected to external electrodes formed on opposite side surfaces, by stacking the piezoelectric ceramic plates by staggering them in one direction, the stacked layers face each other. The protruding portions of the piezoelectric ceramic plate are formed on the respective side surfaces, and the insulating material layers that fill the gaps are formed in the gaps formed between the protruding portions. By forming the external electrodes on opposite side surfaces, the internal electrodes are alternately connected to the external electrodes facing each other. Method for manufacturing laminated piezoelectric actuator.