JPH0542230B

PURPOSE:To improve the moving speed by forming to reduce the lateral sectional shape of a bar-shaped elastic member as compared with the distance from the neutral axis to the surface in sectional secondary radius. CONSTITUTION:A piezoelectric unit 1 is bonded to the bottom of a bar-shaped elastic member 1. Bending vibration is excited by the unit 1 at the axis B as a neutral axis, and surface wave with longitudinal and laterial waves is formed on the surface 2A of the member 1. Thus, the member 1 is formed in a projected sectional shape, the sectional secondary radius decreased as compared with the distance from the neutral axis B to the surface 2A, thereby improving the speed of a movable element. The member may be formed of a member having a cross shaped section, composite material, many platelike members and many notches.