PURPOSE: To prevent the occurrence of a discharge between electrode layers and connecting members by forming a pair of electrode layers on both sides of piezoelectric elements, and applying the voltage so that polarities of electrode layers formed on opposite sides are made the same.
CONSTITUTION: A piezoelectric actuator 3 is constituted of two cylindrical piezoelectric elements 4 and 5 concentrically arranged and having different diameters. Electrode layers are formed on the inner side and the outer side of each piezoelectric element over nearly the whole surface respectively. The voltage is applied so that polarities of electrode layers formed on opposite sides of two adjacent piezoelectric elements 4 and 5 are made the same. No discharge occurs between electrode layers and connecting members.
SAWAI MIKIO
HORIUCHI HIROSHI
ARITA KINYA
