| 摘要 |
PURPOSE:To attain stable correspondence against load fluctuation by detecting plural number of times of generation of a phase detection output in one period of a reference signal so as to apply speed control based on the speed deviation and applying phase control after the speed is made stable. CONSTITUTION:In closing a motor start switch 1, a system control operation section 2 starts a motor 9 via a D/A converter 7 to apply speed control, A mode changeover switch 11 is thrown to the position (a), the content of a timer counter 3 is held in a latch circuit 4 at the leading of an FG pulse signal 12 and the operation section 2 operates a manipulated variable while using the difference of a period of the held signal 12 and a control object period as a deviation. When the speed of the motor 9 is made stable, the switch 11 is switched to the position (b), a reference signal is generated from a control reference signal generating circuit 6, the phase difference of the reference signal and the signal 12 is obtained from the content of the circuit 4 to apply phase control. The speed control is selected after plural number of times of the FG pulses are detected in one period of the reference signal and phase control is applied after the speed stabilization, then stable correspondence is attained.
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