| 摘要 |
A wobble PLL circuit in an optical disk apparatus of the present invention is provided with a modulation and defect detector for measuring a fluctuation between adjoining cycles or a fluctuation of a one cycle interval included in an output signal of the phase comparator, and, if the measurement value exceeds a predetermined threshold value, assuming the measured value as a modulation portion or a defect and masking a feedback signal to a voltage controlled oscillator. As a result, a position of a phase window can be set accuracy, a normal phase comparison can be recognized, and a phase comparison result due to the defect can be masked accuracy, also.
|
