Adhesive bonding and miscellaneous chemical manufacture – Delaminating processes adapted for specified product – Delaminating in preparation for post processing recycling step
Patent
1992-05-06
1993-10-19
Powell, William A.
Adhesive bonding and miscellaneous chemical manufacture
Delaminating processes adapted for specified product
Delaminating in preparation for post processing recycling step
29 2535, 156634, 156655, 156656, 156645, B44C 122, C23F 100
Patent
active
052542122
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of fabricating a lamination-type displacement device (which may be hereinafter referred to as an electrostrictive-effect device) consisting of a lamination of thin sheets of an electromechanical transducer material (that may be hereinafter simply referred to as an electrostrictive material) such as an electrostrictive material or piezoelectric material used for an actuator of an industrial robot, an ultrasonic motor, or the like, the thin sheets being laminated via internal electrodes to increase the amount of displacement. Especially, the invention is intended to selectively insulate the internal electrodes exposed at the side surfaces of the laminate with high reliability.
BACKGROUND ART
Conventionally, a lamination-type displacement device used for a displacement device which is employed in a positioning mechanism for an XY stage, brake, or the like has been manufactured by fabricating thin sheets of a piezoelectric ceramic material shaped in a given form, mounting electrodes on the thin sheets, polarizing them, and then bonding them together directly or via thin sheets of a metal with an organic adhesive. For devices having thin sheets using an adhesive as described above, the displacement induced by vibration of the piezoelectric device may be absorbed by the adhesive layer, depending on the working conditions. The adhesive may deteriorate at high temperatures or after the device has been used for a long time. In this way, devices of this kind have drawbacks.
For this reason, in recent years, lamination-type displacement devices fabricated by the same method as used to manufacture lamination-type chip capacitors have been put into practical use.
One example of the conventional lamination-type displacement device is constructed as shown in FIG. 18. In FIG. 18, thin sheets 41 are made of a piezoelectric ceramic material. Positive internal electrodes 42a alternate with negative internal electrodes 42b in such a way that these sheets are tightened together and stacked on top of each other to form a laminate 45. Each one fringe of the internal electrodes 42a and 42b is so formed as to be exposed. The exposed fringes are connected with external electrodes 43a and 43b extending in the direction of the lamination. Lead wires 46 are connected with the external electrodes via solder 47.
In the structure described above, when positive and negative voltages are applied to the external electrodes 43a and 43b, respectively, an electric field is set up between the internal electrodes 42a and 42b. The thin sheets 41 are elongated in the direction of thickness and produce displacement because of the longitudinal effect of the piezo-electric ceramic material. In this structure, however, the electric field strength is weaker in the marginal regions close to the side surfaces, i.e., in the regions where the internal electrodes 42a and 42b are not laid to overlap each other. Therefore, no deformation is produced. In addition, these portions serve to hinder the deformation of the whole device. Consequently, it is impossible to obtain the amount of distortion intrinsic to the electromechanical transducer material from such an alternate electrode type. Furthermore, the stress is concentrated at the boundary between the displacement portion and the non-displacement portion. If a high voltage is impressed or if a voltage is applied for a long time, the device will be destroyed.
A lamination-type displacement device which is free from the foregoing drawbacks is shown in FIG. 19. This has an improved piezoelectric displacment efficiency, and is known as a so-called total surface electrode type (for example, see Japanese Patent Laid-Open No. 196068/1983). In FIGS. 18 and 19, like components are indicated by like reference numerals. Internal electrodes 42a and 42b are formed over the whole surface of each thin sheet 1. A desired number of thin sheets are laminated in the same way as in the foregoing to form a laminate 45. At one side of the laminate 45 fabricated as des
REFERENCES:
patent: 2998583 (1961-08-01), Worcester
patent: 5163209 (1992-11-01), Harada et al.
Jyoumura Shigeru
Kazama Kazuo
Kojyou Katsuhiko
Someji Takahiro
Tanaka Kiyomi
Hitachi Metals Ltd.
Powell William A.
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