| 摘要 |
PROBLEM TO BE SOLVED: To reduce circuit elements and improve a stability by adjusting a gain of a variable amplification circuit to make a signal amplitude of reproduction signals of first and second pit arrays integrated by a low pass filter a specific value, and detecting a displacement of light beams and tracks from the reproduction signals of the integrated first and second pit arrays. SOLUTION: A first signal is sent via an LPF 146, a D/A converter 147 and an adder 148 to a power amplifier 129, whereby a transfer motor 114 is controlled in accordance with a low frequency component of a first TE signal. An output of an adder 130 becomes a total quantity of light received by a photodetector 113 and is sent to an address reproduction circuit 131. The address reproduction circuit 131 reproduces a sector address, sends to a DSP 140, sends a signal synchronous with the address to a gate generation circuit 132. A VFO1 signal and a VFO2 signal are delayed by a delay circuit by a predetermined time, logically synthesized to be a sampling signal.
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