| 摘要 |
PURPOSE:To switch the outputs of an ultrasonic motor in two stages with a simple constitution. CONSTITUTION:A ring counter 38 outputs the high-level signals in the order of FETs 48, 52, 50 and 54 at the period corresponding to the frequency of the reference signal, which is inputted as a clock signal from an oscillator 36. Thus, the FETs 48-54 are sequentially turned ON in the above described order. The driving signals are induced in the secondary coils of transformers 56 and 58. The driving signals are supplied into piezoelectric bodies 14A and 14B of an ultrasonic motor. When an output-decreasing instruction signal for the ultrasonic motor is inputted, a switch 62 is turned ON. Thus, transistors 68 and 74 are turned ON accordingly. The ON states of the FETs 50 and 54 are stopped. In this way, the voltage level of the driving signal induced in each secondary coil is decreased, so that the output of the ultrasonic motor is decreased. |
