| 摘要 |
PURPOSE:To smoothly operate a motor by varying the frequency of a reference signal at the rising time of the motor in response to the rotating speed of the motor when controlling the motor with a PLL, thereby maintaining the state of the phase synchronizing step at the rising time. CONSTITUTION:When an optical system, a photosensitive unit of a copying machine are individually driven, the output of a clock oscillator 21 is supplied to a frequency divider 22, and the frequency dividing ratio is varied with the time responsive to the rotating speed of the motor 23 at the rising time of the motor 23. The output signal and the output from a rotary encoder 24 shaped in waveform are applied to a phase comparator 26 to operate the motor 23 through a loop filter 27 and a power amplifier 28. When the motor 23 rotates slowly, the frequency of the reference signal applied to the comparator 26 decreases with the result that the frequencies of the two input signals approach to each other. Accordingly, it is always maintained in the state of phase synchronizing step, thereby performing the smooth operation. |
