JPH08250777A - Coupled multilayer piezoelectric actuator element - Google Patents

Abstract

PURPOSE: To provide a coupled multilayer piezoelectric actuator element formed with external electrodes never broken even if driven continuously. CONSTITUTION: In a coupled multilayer piezoelectric actuator element 1a of a structure, wherein a plurality of multilayer bodies 1 are formed by a method, wherein material having an electrostrictive effect and internal electrodes 7a and 7b are alternately stacked and the internal electrodes 7a and 7b are connected with one pair of external electrodes 3 on every other layer, and the plurality of multilayer bodies 1 are coupled together in series via adhesion layers 4, the external electrodes 3 between the multilayer bodies 1 are electrically coupled together and conductor wires 5 secured on parts excluding at least the layer 4 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connected laminated piezoelectric actuator element which is connected in series to generate a large displacement.

[0002]

2. Description of the Related Art A laminated piezoelectric actuator element is constructed by alternately laminating a material exhibiting an electrostrictive effect and internal electrodes, and connecting external electrodes to the internal electrodes every other layer on both side surfaces of the laminated body. The so-called alternating electrode type in which the internal electrodes are alternately exposed on one side surface of the laminated body and connected to the external electrodes, and the internal electrodes are formed so as to be exposed on both side surfaces of the laminated body. There is a so-called full-surface electrode type in which exposed portions are covered with an insulating material every other layer and connected to external electrodes.

By connecting a plurality of such laminated piezoelectric actuator elements in series in the laminating direction, an element having a large displacement amount can be obtained. FIG. 4 shows an example of a conventional connected laminated piezoelectric actuator element, in which the protective layer 2 portion of the laminated body 1 containing the internal electrodes 7a and 7b is connected via an adhesive layer 4, and the external electrode 3 is laminated. It is formed by baking the conductive paste after the body 1 is bonded and connected. In this connected laminated piezoelectric actuator element, when a voltage is applied to the laminated body 1 via the external electrode 3, the laminated body 1 has characteristics of not only vertically extending but also contracting to the left and right. As shown in FIG. The upper and lower end surfaces including the protective layer 2 portion of No. 1 are not flat but curved surfaces.
The part opens wide. Therefore, there is a drawback that the external electrode 3 is broken at the adhesive layer 4 portion. Therefore, it is conceivable to embed the lead wire over substantially the entire length of the external electrode 3 to reinforce it, but tensile stress acts continuously,
There is a defect that the lead wire is broken due to metal fatigue.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a connected laminated piezoelectric actuator element having an external electrode which does not break even when continuously driven. The purpose is to

[0005]

In order to achieve the above-mentioned object, according to the connected laminated piezoelectric actuator element of the present invention, a material exhibiting an electrostrictive effect and internal electrodes are alternately laminated, and the internal electrodes are In a connected laminated piezoelectric actuator element in which a plurality of laminated bodies each of which is connected to a pair of external electrodes every other layer are coupled in series via an adhesive layer, the external electrodes between the laminated bodies are electrically coupled, At least the portion excluding the adhesive layer is provided with a conductive wire. In particular, the conductive wire has a continuous curved portion in the shape of a sine curve or a semi-circular arc, and at least the peaks or valleys of the curved portion are arranged in contact with or close to each other, and the adhesive layer is formed. It is characterized in that it is fixed to the external electrode at a portion other than the portion.

[0006]

According to the present invention, even if the upper and lower end surfaces of the laminated body are curved and the adhesive layer portion is largely opened by driving the connected laminated piezoelectric actuator element, the conductor wire is not fixed to the laminated body in the adhesive layer portion. Is loose and is in a non-tensioned state, and since the conductor wire is fixed to the external electrode at the part excluding the adhesive layer, the conductor wire operates regardless of the condition of the external electrode in the adhesive layer part, so malfunction due to disconnection It is possible to continuously drive the connected laminated piezoelectric actuator element without causing

[0007]

Embodiments of the present invention will now be described with reference to the drawings, in which the same parts as those shown in the previous drawings are designated by the same reference numerals. Referring to FIG. 1, in the connected laminated piezoelectric actuator element 1a of the present invention, a plurality of laminated bodies 1 are vertically connected (laminated) via an adhesive layer 4 and the external electrodes 3 between the laminated bodies 1 are connected. Is mainly configured by being fixed and bonded to the conductive wire 5 at least in the portion excluding the adhesive layer 4.

In the laminate 1, a material exhibiting an electrostrictive effect and internal electrodes 7a and 7b are alternately laminated, and the internal electrodes 7a and 7b are laminated.
b is connected to a pair of external electrodes 3 every other layer. For example, a known binder, solvent, dispersant, defoaming agent, etc. are added to PZT fine powder and dispersed by a mixer such as an attritor. Thereafter, the slurry obtained by vacuum degassing was molded into a sheet having a thickness of 100 μm by a doctor blade method, and Ag / Pd paste was screen-printed on the sheets as internal electrodes 7a and 7b. It is obtained by stacking, press-bonding together with the upper and lower protective layers 2, firing, and then cutting into predetermined dimensions. The external electrodes 3 are formed by baking a conductive paste such as Ag on the left and right side surfaces of the laminated body 1, and the protective layer 2 portions of the plurality of laminated bodies 1 are bonded by an adhesive such as epoxy and connected, and then the protective layer is formed. Alternatively, the conductive paste may be baked and formed by connecting between the respective laminated bodies 1 including 2 and the adhesive layer 4 portion. The electrode structure may be either the alternating electrode type or the full-face electrode type described above.

It is desirable that the outer electrode 3 be coated with a low melting point alloy such as solder over substantially the entire length of the outer electrode 3, and the laminated body 1 expands and contracts by applying and releasing a voltage. It is possible to prevent the occurrence of cracks or disconnection due to the stress acting on the electrode 3. The deposition of the external electrode 3 with the low melting point alloy can be performed together with the conductor wire 5 and the lead wire 6 which will be described later.

The conducting wire 5 provided on both side surfaces of the plurality of connected laminated bodies 1 as described above has a sinusoidal continuous bent portion 5a as shown in FIG. 1 or a semi-arcuate shape as shown in FIG. Of the bent portion 5a, at least the peaks or valleys 5b of the bent portion 5a, that is, the adhesive layer 4 portion of the laminate 1, preferably the protective layer 2 and the adhesive layer 4 portion. It is fixed to the external electrode 3 by soldering or the like.

On the other hand, the ridges or valleys 5b of the conductive wire 5 are arranged in contact with or close to the protective layer 2 and the adhesive layer 4 of the laminate 1 in a non-fixed state. That is, the conductive wire 5 is brought into a loosened non-tension state with the laminated body 1 at this portion.

Next, the lead wire 6 is fixed to at least one end of the external electrode 3 by soldering or the like. However, the present invention is not limited to the illustration, and the tip of the lead wire 6 may also serve as the conductor wire 5. Alternatively, the lead wire 6 may be fixed over the entire length of the external electrode 3 separately from the conductive wire 5, and the lead wire 6 may be attached together with the external electrode 3 by a low melting point alloy as described above.

In the above-described connected laminated piezoelectric actuator 1a of the present invention, when a drive voltage is applied to the lead wire 6, an electric field is generated between the internal electrodes 7a and 7b built in the laminated body 1 via the external electrode 3. Actuator 1
a extends in the stacking direction and causes displacement. In this case, the protective layer 2 portion on the upper and lower end surfaces of each laminate 1 is curved like the one shown in FIG. 4, and the adhesive layer 4 portion is wide open, but in the present invention, it is shown in FIG. As described above, since the conductive wire 5 is arranged in a loose and non-tensioned state at the adhesive layer 4 portion, when the repeated action of severe expansion and contraction of voltage application and release to the laminated body 1 is repeated, the adhesive layer 4 portion is externally connected. Even if the electrode 3 is broken, the conducting wire 5 operates without breaking, and the connected laminated piezoelectric actuator element 1a of the present invention can be suitably and continuously driven.

Further, in such a severe continuous drive, disconnection or breakage of the external electrode 3 in a portion other than the adhesive layer 4 is also caused by depositing the external electrode 3 by the low melting point alloy over substantially the entire length, or , The external electrode 3 of the lead wire 6
Can be effectively prevented by sticking or the like over almost the entire length.

[0015]

According to the present invention, it is possible to provide a connected multi-layer piezoelectric actuator element that generates a large amount of displacement without causing disconnection in the connected adhesive layer portion.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a connected laminated piezoelectric actuator of the present invention.

FIG. 2 is a schematic perspective view showing another embodiment of the connected laminated piezoelectric actuator of the present invention.

FIG. 3 is a partial cross-sectional view showing an operating state of the connected laminated type voltage actuator of the present invention.

FIG. 4 is a partial cross-sectional view showing a conventional connected laminated piezoelectric actuator.

FIG. 5 is a partial cross-sectional view showing an operating state of a conventional connected laminated piezoelectric actuator.

[Explanation of symbols]

 1a Connected laminated piezoelectric actuator 1 Laminated body 2 Protective layer 3 External electrode 4 Adhesive layer 5 Conductive wire 5a Bent portion 5b Mountain or valley portion 6 Lead wire 7a Internal electrode 7b Internal electrode

Claims (8)

[Claims] 1. A plurality of laminates in which a material exhibiting an electrostrictive effect and internal electrodes are alternately laminated, and the internal electrodes are connected to a pair of external electrodes every other layer in series with an adhesive layer interposed therebetween. In the coupled multi-layer piezoelectric actuator element that is combined,
A connected laminated piezoelectric actuator element, characterized in that an external electrode between each laminated body is electrically coupled and is provided with a conductive wire fixed at least at a portion excluding the adhesive layer. 2. A plurality of laminates in which a material exhibiting an electrostrictive effect and internal electrodes are alternately laminated are connected in series via an adhesive layer, and the internal electrodes are paired every other layer. In the connected laminated piezoelectric actuator element connected to the electrodes, the external electrodes between the laminated bodies are electrically coupled,
At least a portion excluding the adhesive layer is provided with a conductive wire, which is a laminated piezoelectric actuator element. 3. The conductive wire is bent in a sine curve shape, and at least peaks or troughs of the sine curve and the adhesive layer are arranged in contact with or close to each other, and in a portion excluding the adhesive layer. The connected laminated piezoelectric actuator element according to claim 1 or 2, which is fixed to the external electrode. 4. The adhesive layer has a continuous bent portion in the shape of a semicircle, and at least peaks or troughs of the bent portion are arranged in contact with or close to the adhesive layer. 3. The connected laminated piezoelectric actuator element according to claim 1, wherein the piezoelectric element is fixed to the external electrode at a portion except for. 5. The coupled multi-layer piezoelectric actuator element according to claim 1, wherein the external electrode is covered with a low melting point alloy over the entire length of the external electrode. 6. The connected multi-layer piezoelectric actuator element according to claim 1, wherein a lead wire is fixed to at least one end of the external electrode. 7. The connected multilayer piezoelectric actuator element according to claim 1, wherein the lead wire is fixed to the external electrode over substantially the entire length of the external electrode. 8. The connected multi-layer piezoelectric actuator element according to claim 1, wherein the conductive wire also serves as a tip portion of the lead wire.