| 摘要 |
PROBLEM TO BE SOLVED: To precisely control rotational operation of a scanner without increasing a circuit scale and a cost by controlling the rotational drive operation of a drive means according to combination between signal levels of a speed control signal and a phase control signal. SOLUTION: A speed control part 11 respectively makes a VAAC signal only for a period that the period of the BD signal is longer than the prescribed period, and a VDEC signal only for a period that the period of the BD signal is shorter than that a LOW level. A phase comparison part 12 inputs a prescribed rotation reference signal RefBD signal, and the signal (m) frequency dividing the output BD signal of the BD sensor 18 with a frequency divider 21, and respectively makes a lag signal only for the period that the BD signal is phase delayed than the RefBD signal, and a lead signal only for the period that the BD signal is phase advanced the LOW level. An AND circuit 13, from the VAAC signal and the lag signal, and the AND circuit 14, from the VDEC signal and the lead signal, respectively synthesizes an ACC signal, a DEC signal respectively controlling a charge pump 15.
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