| 摘要 |
PROBLEM TO BE SOLVED: To realize the stable operation of an ultrasonic motor, even if the size and thickness of the motor are reduced and realize the high driving efficiency of the ultrasonic motor. SOLUTION: If the wavelength of a standing wave excited on the vibration unit 3 of an ultrasonic motor is denoted by λ, the wave number of the standing wave is denoted by (n), the position of the node part of the vibration is expresses by a formula: i λ/2 (where (i) denotes an integer from 0 to 2n) and the position of the loop part of the vibration is expressed by a formula: (2j-1) λ/4 (where (j) denotes an integer from 1 to 2n), (2n) protrusions la are provided on the vibration unit 3 approximately on one circle and with uniform intervals, approximately equivalent to a λ/2 period, and furthermore, the positions of the (2n) protrusions 1a in the circumferential direction are within a range larger than kλ/2, and smaller than (4k+1) λ/8 (where (k) denotes an integer from 0 to 2n-1). |
