Laminate type piezoelectric actuator element

Claim 1

A laminate piezoelectric actuator element for generating a longitudinal electrostrictive strain through a piezoelectric/electrostrictive longitudinal effect with a voltage, comprising: plural laminated piezoelectric subunits each comprising piezoelectric ceramic layers for generating the longitudinal electrostrictive strain therethrough with an applied voltage thereto, internal electrode layers each comprising an internal electrode and a drawing electrode for applying the voltage to said piezoelectric ceramic layers, and piezoelectrically-inactive portions for generating no longitudinal electrostrictive strain, said piezoelectric ceramic layers and said internal electrode layers being alternatingly laminated on each other, and said internal electrodes having an area smaller than an area of said piezoelectric ceramic layers to define said piezoelectrically-inactive portions as parts of said piezoelectric ceramic layer having no internal electrodes laminated thereon; an adhesive member for attaching said laminated piezoelectric subunits to one another therethrough, an attaching area of said adhesive member being equal to or smaller than the area of said internal electrodes to thereby form slit portions between said laminated piezoelectric subunits in such a manner as to surround said adhesive member, wherein said plural piezoelectric element subunits are laminated through the adhesive member in a laminating direction thereof; and external electrodes provided at both sides of said piezoelectric subunits in such a manner as to be connected to said internal electrode through said drawing electrode to apply the voltage to said internal electrode.