Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1992-01-30
1993-10-12
Budd, Mark O.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310366, 310368, H01L 4108
Patent
active
052528839
ABSTRACT:
A laminated type piezoelectric actuator having a laminated body formed by alternately laminating piezoelectric ceramic layers and internal electrode layers, each of which are approximately the same shape. The four corners or edges of each layer of the ceramic layers and the internal electrode layers, which edges extend in parallel with the lamination direction of the laminated body, are machined to form a convex, arcuate shape or an angled, planar shape. This enables the end parts of each layer, which have a high distribution density of microcracks, to be removed, so that interlayer short-circuiting between the internal electrode films caused by the microcracks is prevented. Accordingly, the operation life and the reliability of the actuator of this invention is extended and improved, respectively, even when it is driven by a driving voltage which is exactly or close to that of a dc voltage in a highly humid environment. By using a Pb (Ni.sub.1/3 Nb.sub.2/3) O.sub.3 --PbTiO.sub.3 --PbZrO.sub.3 system perovskite structure compound oxide as the piezoelectric ceramic piece, and removing each of the four edges in the cross section to exhibit a convex, arcuate shape with a radius of curvature equal to or greater than 1.0 mm, or an angled, planar shape having a chamfering length equal to or greater than 0.8 mm, it is possible to increase the life of the actuator to about 10 times that of the actuator of the prior art.
REFERENCES:
patent: 2479926 (1949-08-01), Gravley
Budd Mark O.
NEC Corporation
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