| 摘要 |
PURPOSE:To prevent production of offensive noise at the time of motor lock by providing a rotor drive voltage generating means for applying a high frequency voltage onto a stator, means for detecting the state prevailing immediately before lock, and a control means for providing a start command and stopping the bending vibration of the stator based on an output signal from the detecting means. CONSTITUTION:A control means 15, i.e., a control circuit 33, provides a control signal to the drive circuit 36 for a ultrasonic motor 11 based on ON signals of operating switches 34, 35. A control command for stopping the ultrasonic motor 11, immediately before it is over loaded, is provided to the drive circuit 36 based on ON signals of limit switches 31, 32. The drive circuit 36 functions as a drive signal generating means 13 and comprises a variable frequency oscillator 361, an amplifier 362 for amplifying the output from the variable frequency oscillator 361, and an amplifier 364 for amplifying the output from a phase shifter 363 and feeding the amplified output to a stator 11a. Relay contacts 365, 366 turn OFF the motor based on a stop command signal 33b. |
