| 摘要 |
PURPOSE:To operate stably against fluctuation of load by controlling a drive circuit through a variable-frequency oscillator so that constant power is applied onto a piezoelectric member based on the voltage to be applied onto the piezoelectric member, the current proportional to the vibration of mechanical system and flowing through the piezoelectric member, and the phase difference signal between the voltage and the current. CONSTITUTION:A means 4 for detecting the voltage to be applied onto a motor and a means 5 for detecting current proportional to the mechanical system vibration in the motor are connected with a phase difference detecting means 6, and phase difference is detected based on output signals from the voltage detecting means 4 and the current detecting means 5. The voltage detecting means 4, the current detecting means 5 and the phase difference detecting means 6 are connected with a power detecting means 7, and power to be applied onto an ultrasonic moy motor 1 is obtained. The power detecting means 7 is connected with a level comparator 8 in order to obtain a power error. The level comparator 8 is connected with a variable-frequency oscillator 2 and controlled so that constant power is fed to the ultrasonic motor 1. |
