| 摘要 |
PROBLEM TO BE SOLVED: To reduce a slippage between a vibrator and a relative motion member when intermittently driven and thereby suppress the abrasion on a contact face between these members, by changing the frequency of AC voltage for at least a part of the period during which AC voltage is applied to an electromechanical transducing element. SOLUTION: A pulse setting device 30 sets the applying time and the frequency of a driving signal to prescribed values, based on a target speed. A pulse generator 31 generates a pulse signal S1 having the pulse width and the pulse frequency accomodating the set values. A control signal generating section 32 generates a frequency control signal S2. An oscillator circuit 16 outputs a frequency signal S3 controlled by the frequency control signal S2 when the pulse signal S1 is ON. Then the frequency signal S3 is inputted to input regions 13a and 13c through an amplifier 17a while also being inputted to input regions 13b and 13d through a phase shifter 18 and an amplifier 17b. A speed control circuit 19 controls the pulse setting device 30 according to the output voltages from detection regions 13p, 13p'. |
