| 摘要 |
PURPOSE:To accurately and stably control the speed of an ultrasonic motor with respect to variation in a load of a wide range. CONSTITUTION:A speed command circuit 41 varies a reference DC voltage from a reference voltage generator 39 by a converted DC voltage from an amplifier 45 and outputs a DC speed command voltage. A voltage/frequency converter 47 coverts the speed command voltage into a frequency signal according to its level, and outputs it to a driving circuit 49. The circuit 49 forms a driving voltage from the frequency signal to drive an ultrasonic motor 43. A rotary encoder 59 coupled to the motor 43 generates a frequency signal according to the speed, and outputs it through a waveform shaping circuit 61. A frequency/voltage converter 63 converts the frequency signal into a DC voltage corresponding to the frequency, and the amplifier 45 feeds back the converted DC voltage to the circuit 41. |
