| 摘要 |
PURPOSE:To stabilize the operation of a servo system and to improve the quality of a reproduced sound by using a signal formed based on a frequency division output of a crystal oscillator and a reproduced digital sound signal so as to apply phase servo control to a disk drive motor. CONSTITUTION:In reproducing an optical digital audio disk, a motor 18 is phase-locked by a write frame clock WFCK extracted from a reproducing signal of an optical pickup 11 and a read frame clock RFCK from a crystal oscillator 14F by a signal processing circuit 13 and driven at a constant line velocity. In reproducing an optical video disk, a reproducing signal is separated by a low pass filter 22, the motor 18 is phase-locked by the clocks WFCK and RFCK and driven at a constant line velocity. Further, a crystal oscillator 26V is phase-locked to a horizontal synchronizing signal separated from the reproduced video signal at a synchronization separator circuit 24. Through the constitution above, since the motor 18 is phase-locked to the clock CFCK, the operation of the servo system is stabilized. Further, jitter or wow of the reproduced sound data during extended period is eliminated.
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