| 摘要 |
PROBLEM TO BE SOLVED: To obtain a stable output signal by applying a masking processing to a carrier wave and the result of a phase comparison in order to generate a detection window and to detect a wobble signal. SOLUTION: A carrier wave reproducing circuit 11 detects a carrier wave by receiving a reflected light from an optical disk to outputs the signal of the carrier wave and a VOC (voltage controlled oscillator) 13 outputs a signal whose oscillation frequency is controlled based on the voltage of an input signal and a clock signal generating circuit 14 generates a clock signal in which the signal outputted from the VOC 13 is frequency divided to one nth and outputs the clock signal and a detection window generating circuit 16 generates the signal of the detection window of the carrier wave based on the clock signal outputted from the circuit 14 and outputs the signal of the detection window and a phase comparator 12 compares the phase of the signal of the carrier wave with the phase of the signal of the detection window and outputs the signal of the phase difference based on the compared result as the input signal of the VOC 13 and, thus, the width of the detection window is made to be arbitrarily changed.
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