To provide a drive circuit of an ultrasonic motor capable of performing drive control of the ultrasonic motor easily and surely with high drive efficiency through a simple arrangement, and to provide an actuator.
The drive circuit 5 of an ultrasonic motor 2 comprises a circuit for driving the ultrasonic motor equipped with an oscillator having a piezoelectric element telescoping upon application of an AC voltage and a portion butting against a driven element, a means for generating pulse signals periodically, a means for setting a unit period periodically, a means for adjusting the number of pulses in the unit period of a pulse signal while sustaining the period of the pulse signal, and a means for driving the ultrasonic motor 2 by applying an AC voltage corresponding to the adjusted pulse signal to the piezoelectric element wherein drive control of the ultrasonic motor 2 is carried out by adjusting the number of pulses in the unit period through the number of pulse adjusting means.
Fujitsuna Hideyoshi
Osamu Suzawa