Patent ID: 8314532

Claim:
A drive device, comprising: a stator; a rotatably-provided drive member; a piezoelectric element, which is nipped between the stator and the drive member in a tangential line direction of a rotation locus circle of the drive member, and expands and contracts in the tangential line direction at an expansion speed at a time of expansion and a contraction speed at a time of contraction, respectively, the expansion speed and the contraction speed being different from each other; a rotor, provided concentrically with the drive member to touch the drive member with a pressure; and an urging section to urge the drive member to compress the piezoelectric element along the tangential line direction of the rotation locus circle of the drive member; wherein one end of the piezoelectric element is fixed to the stator, and the other end of the piezoelectric element abuts against the drive member in an unfixed state; and wherein the drive member has a hemispherical projection at a part where the drive member contacts with the piezoelectric element.