Patent ID: 7825566

Claim:
An ultrasonic actuator, comprising: a vibrating member which includes a piezoelectric deformation portion and deforms by a driving signal; the piezoelectric deformation portion including: a plurality of piezoelectric layers made of a piezoelectric material; a plurality of internal electrode layers alternately laminated with the piezoelectric layers, each of the internal electrode layers being divided into a plurality of internal electrodes, each of which is applied with the driving signal, wherein a cross section of the vibrating member perpendicular to a direction of the lamination is a substantially triangular shape having three vertices; and a plurality of external electrodes which are integrally provided on a side surface including one side of the triangular shape, each of the external electrodes electrically interconnecting internal electrodes, which are overlapping one another in the direction of the lamination, in a predetermined combination, and a moving member which has a hollow cylindrical shape and is pressure-contacted with the vibrating member at the three vertices and moves relatively to the vibrating member by a deformation motion of the vibrating member, and the external electrodes are disposed only on one side surface including any one side of the triangular shape, wherein each of the divided internal electrodes in each of the internal electrode layers include 6 internal electrodes, each pair of which are disposed in correspondence to each of the three vertices, the piezoelectric deformation portions deforms by the driving signal supplied to the internal electrodes through the external electrodes, the deformation causes elliptical vibrations in the three vertices of the vibrating member in a same direction, and the elliptical vibrations cause the moving member to move relatively to the vibrating member.