Mitsui Toatsu Chemicals, Incorporated

Atsushi Hagimura

Mutsuo Nakajima

Kunio Nishihara

Ikuo Inage

A multi-layered electrostrictive effect element comprises films or thin plates of an electrostrictive material and inner electrodes alternatively arranged in layers, the inner electrodes being formed on the entire surface of the films or thin plates of the electrostrictive material, wherein the insulating layer which insulates the inner electrodes exposed on the side end faces of the element comprises a polyimide resin having repeating units represented by the following general formula (I): ##STR1## (wherein X represents a tetravalent group selected from the group consisting of tetravalent phenyl groups; tetravalent biphenyl groups; and tetravalent polyphenyl groups in which at least one of either the phenyl or bipheny groups are bonded through at least one member selected from the group consisting of O, CO, S, CH.sub.2, C(CH.sub.3).sub.2 and C(CF.sub.3).sub.2 and Y represents a bivalent groups selected from the group consisting of bivalent phenyl groups; bivalent biphenyl groups; bivalent polyphenyl groups in which at least one of either the phenyl or biphenyl groups are bonded through at least one member selected from the group consisting of O, CO, S, SO.sub.2, CH.sub.2, C(CH.sub.3).sub.2 and C(CF.sub.3).sub.2 ; alkylene groups; and xylylene groups) and an insulating filler. A process for making a multi-layered electrorestrictive effect element having a high dielectric strength is also disclosed.

Multi-layered electrostrictive effect element

The present invention relates to a longitudinally effective piezoelectric element exhibiting a large displacement at low voltage and to a ceramic composition suitable for producing the longitudinally effective piezoelectric element.

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Kamakura, Japan

Atsushi Hagimura