Piezoelectric/electrostrictive actuator

A piezoelectric/electrostrictive actuator comprising a piezoelectric body and a plurality of internal electrode layers formed in parallel within the piezoelectric body, in which a predetermined voltage is applied to the internal electrode layers so as to expand and contract the piezoelectric body,

• wherein the internal electrode layers are disposed at a central portion of the piezoelectric body such that an active portion and an inactive portion are formed in the piezoelectric body, the active portion being the central portion of the piezoelectric body to which a voltage is applied so as to expand and contract the piezoelectric body, and the inactive portion being a peripheral portion of the piezoelectric body which surrounds the central portion of the piezoelectric body and in which no voltage is applied to the piezoelectric body and the piezoelectric body neither expands nor contracts, and
• wherein the piezoelectric/electrostrictive actuator further comprises:
• electrode lead portions each generally assuming the form of a strip and extending from the internal electrode layers to side surfaces of the piezoelectric body, the width of the strip being equal to or less than 30% the diameter of a circle which can be drawn in an internal electrode layer without extending outside the outer edge of the internal electrode layer, and the circle having the maximum area among all such circles;
• and
• side-surface electrodes formed on the side surfaces of the piezoelectric body so as to connect together end portions of the corresponding electrode lead portions exposed to the side surfaces of the piezoelectric body.