| 摘要 |
PROBLEM TO BE SOLVED: To reduce the dimension in the travel direction of an ultrasonic motor without impairment of driving force, and achieve miniaturization of a drive device by using the ultrasonic motor.SOLUTION: An ultrasonic motor comprises: a diaphragm which has a rectangular surface; a piezoelectric element which is attached to the diaphragm and vibrates at a high frequency; and a protrusion which is provided on the diaphragm or the piezoelectric element. The natural vibration mode which has a resonant frequency matching or adjacent to the resonant frequency of the natural vibration mode of torsional vibration in the state where the diaphragm, the piezoelectric element and the protrusion are integrated is the natural vibration mode of flexural vibration in a direction parallel to or orthogonal to the torsional center axis of the natural vibration mode of the torsional vibration, and the protrusion is provided at a position closer to the loop than the node of the node and the loop in the direction orthogonal to the torsional center axis of the natural vibration mode of the torsional vibration.SELECTED DRAWING: Figure 1 |
