Patent ID: 7679265

Claim:
A drive unit comprising: a stationary body; a movable body which is movable relative to the stationary body; a vibration actuator using a piezoelectric element for moving the movable body; and a control section for controlling the vibration actuator by feeding the piezoelectric element, wherein the vibration actuator includes two driver elements spaced apart at an interval in a moving direction of the movable body and in contact with one of the movable body and the stationary body and is fixed to the other one of the movable body and the stationary body, a surface of the one of the movable body and the stationary body in contact with the driver element is an undulating surface, the control section detects the position of the movable body based on a change in contact pressure on the driver element due to the undulating surface, and the undulating surface includes at least one of a concavity and a convexity having a width larger than the interval between the driver elements.