| 摘要 |
PURPOSE:To perform low speed control with no cogging and to perform highly accurate positional control by eliminating apparent dead zone in the vicinity of 0 operational output or 0 angular speed when positional control or speed control is made. CONSTITUTION:Oscillation frequency of a variable oscillator 2 is controlled through a variable oscillator control circuit. A signal fed from a 90 deg. phase shifter 3 for producing two 90 deg. phase shifted signals from the output of the variable oscillator 2 is amplified to the voltage level for driving on ultrasonic actuator 6 and applied onto the electrodes of a piezoelectric body 10, where the amplitude is controlled through power amplifiers 4, 5 based on DC voltage being applied onto the control input. A CPU 7 provides on operational output to a D/A converter 8 based on positional information fed from a position detector 9. A piezoelectric body 12 is driven with ultrasonic frequency voltage so that elastic wave is excited in the vibrator 12 comprising the piezoelectric body 12 and a resilient body 14. An ultrasonic actuator 6 for moving a moving body 15 is arranged on the vibrator 14. |
