The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 12, 1993
Filed:
Jan. 30, 1992
Masahiro Kondo, Tokyo, JP;
NEC Corporation, Tokyo, JP;
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.