| 摘要 |
PURPOSE:To obtain an efficiently and stably operating supersonic motor by bringing a drive frequency in coincidence with the resonance frequency of a driver at starting and operating times, and absorbing the variation in its impedance by altering the gain of an amplifier. CONSTITUTION:A circular piezoelectric ceramic unit 2 is bonded to a circular elastic unit to form a piezoelectric driver, a movable unit is contacted with the driver to form a supersonic motor. An electric field is applied to the unit 3 to rotate the movable unit. The drive by the application of an electric field is started by power amplifiers 12, 13 through an amplifier 8 and one through a 90 deg. phase shifter 11 to drive the drive frequency from an oscillator 7. In this case, an analog switch 10 which is closed by the H output of a buffer 9 is provided, and both of the switches 10 are closed immediately after starting. Thus, the oscillating frequency of the oscillator 7 becomes high by the parallel resistance values of resistors R1, R2, and the gain of the amplifier 8 becomes small. Thus, the motor is always efficiently and stably driven during the operation at starting time. |
