| 摘要 |
PURPOSE: To provide a driving apparatus for ultrasonic motors wherein driving frequency is capable of being varied so that phase difference between voltage applied to a plurality of laminated piezoelectric elements and current passing through them will fall within a specified range, and being thereby optimized. CONSTITUTION: An ultrasonic motor includes an elastic body and an ultrasonic piezoelectric transducer composed of a plurality of laminated piezoelectric elements secured on the elastic body. A driving apparatus for ultrasonic motors moves a mobile body by applying a.c. voltages, different in phase from each other, to these laminated piezoelectric elements by means of a two-phase oscillator 1 and thereby generating ultrasonic oscillation. In the driving apparatus one of the plurality of the laminated piezoelectric elements 113A, 113B is selected according to the direction of the movement of the mobile body. The driving apparatus is provided with means 4, 5, 6, 7, 8, 9 for so controlling the frequency of a.c. voltage that phase difference between the a.c. voltage applied to a selected laminated piezoelectric element and current passing through the piezoelectric element will be a specified value. |
