Patent ID: 8446066

Claim:
An ultrasonic motor comprising: an oscillator whose cross section vertical to a central axis has a rectangular shape and which generates elliptic oscillation when longitudinal oscillation that expands or contracts in the central axis direction and torsional oscillation using the central axis as a torsional axis are simultaneously excited, a length ratio of a narrow side and a wide side constituting the rectangular shape being set to a predetermined value; a driven body that comes into contact with an elliptic oscillation generation surface of the oscillator in which the elliptic oscillation is generated and is driven to rotate by the elliptic oscillation around the central axis; and a pressing mechanism unit that presses the oscillator against the driven body and welds the elliptic oscillation generation surface of the oscillator to the driven body by pressing, wherein the oscillator comprises driving electrodes and oscillation detecting electrodes near a node portion of the longitudinal oscillation and near ventral portions of the torsional oscillation, an external electrode achieving electrical conduction with the driving electrodes and an external electrode associated with one polarity of an external electrode achieving the electrical conduction with the oscillation detecting electrodes are formed on a first surface of outer surfaces of the oscillator, and an external electrode associated with the other polarity of the external electrode achieving the electrical conduction with the oscillation detection electrodes is formed on a second surface different from the first surface of the outer surfaces of the oscillator.