Patent ID: 7157834

Claim:
A rotation/displacement converting actuator comprising: a rotor provided in a rotatable manner, said rotor having an outer circumferential surface and a lateral face; a vibrating element which includes a first piezoelectric element that undergoes extension and contraction by application of an AC voltage, a reinforcing plate having an abutting portion and an arm portion, and a second piezoelectric element that undergoes extension and contraction by application of an AC voltage, the first piezoelectric element, the reinforcing plate and the second piezoelectric element being laminated in this order, and the vibrating element being supported by the arm portion so that the abutting portion abuts on the outer circumferential surface of said rotor from a radial direction of said rotor wherein said vibrating element undergoes vibration by applying an AC voltage to the first and second piezoelectric elements so that said vibrating element repeatedly applies force to said rotor by the vibration to rotate said rotor; a displacing body provided in a linearly movable manner, the displacing body having an end portion; and a converting mechanism for converting rotary motion of said rotor to reciprocal motion of said displacing body, said converting mechanism including a crank mechanism, wherein the crank mechanism has a crank rod having two ends, and one of the two ends of the crank rod is rotatably coupled to the lateral face of said rotor at a position spaced apart from a center of rotation of said rotor by a predetermined distance by a crank pin and the other of the two ends of the crank rod is coupled to the end portion of said displacing body by a crank pin.