Patent ID: 7633213

Claim:
An actuator comprising: a base having an insulating surface; an elastic arm, the arm including: a supported portion supported by the base; a movable portion; a first surface on the movable portion of the arm facing the surface of the base; and a second surface on a side of the movable portion of the arm opposite to the first surface; a first electrostatic-driving electrode provided on the base and facing the arm; a second electrostatic-driving electrode provided at the movable portion of the arm and on the first surface, the second electrostatic-driving electrode facing the first electrostatic-driving electrode; a first piezoelectric-driving layer disposed on the second surface of the arm, the first piezoelectric-driving layer including: a first electrode layer provided on the second surface of the arm; a first piezoelectric layer provided on the first electrode layer; and a second electrode layer provided on the first piezoelectric layer; and a second piezoelectric-driving layer disposed on the second surface of the arm, the second piezoelectric-driving layer including: a third electrode layer provided on the second surface of the arm; a second piezoelectric layer provided on the third electrode layer; and a fourth electrode layer provided on the second piezoelectric layer, wherein the arm has an axis passing through the supporting portion and the movable portion, and wherein the first piezoelectric-driving layer and the second piezoelectric-driving layer are provided at positions symmetric with each other about the axis.