ULTRASONIC MOTOR

PROBLEM TO BE SOLVED: To provide an ultrasonic motor comprising a single member, having a simple structure without requiring a groove and the like, facilitating to excite longitudinal oscillation and twisting oscillation, forming elliptic oscillation by combining the longitudinal oscillation and the twisting oscillation, and allowing a rotor to rotate by the elliptic oscillation. SOLUTION: The ultrasonic motor 10 includes at least a piezoelectric element 11 as an oscillator whose section perpendicular to a central axis has a rectangular length ratio, and a rotor 16 that is driven and rotated about the central axis as a rotation axis while being in contact with an elliptic oscillation generating surface of the piezoelectric element 11, the central axis being orthogonal to the elliptic oscillation generating surface of the oscillator. The elliptic oscillation is formed by combining first longitudinal resonance oscillation in which expansion and contraction are performed in a rotation axis direction of the piezoelectric element and second twisting resonance oscillation in which the rotation axis is a twisting axis. COPYRIGHT: (C)2010,JPO&INPIT