To improve controlling responsiveness by reducing a microscopic change of a frictional drive force generated from a vibrator in a standing wave ultrasonic motor.
The ultrasonic motor 10 includes a vibrating part 24 having one vibrator 14, and two pairs of exciting elements 16 mounted in the vibrator 14. A controller 22 controls the two pairs of the exciting elements 16 so that two exciting elements 16 which form each pair of the two pairs of the exciting elements 16 generate high frequency displacing operations of different phases from each other to create an elliptical motion in the drive surface 12 of the vibrator 14 and it becomes a state that phases of the high frequency displacing operations of all the exciting elements 16 become regularly deviated from each other. More particularly, a control of applying drive voltages of V=αsin{ωt-(m-1)π}, V=αcos{ωt-(m-1)π} to the two exciting elements 16 for forming the m-th (m=1 or 2)pair is performed.
Jun Tsuruta
Tetsuro Shimada
Masaya Nishiyama
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