| 摘要 |
PROBLEM TO BE SOLVED: To accurately access a desired track by preventing an influence of noise of a wobble signal or the like and detecting stably appropriate pre-pit information. SOLUTION: A push-pull signal Ps in accordance with difference of output signals from two light receiving regions 26a, 26b of a light receiving means in an optical pickup Ps is obtained by an arithmetic circuit 9, a peak value of the push-pull signal Ps is detected by a pre-pit peak value detecting circuit 30 in a pre-pit detecting circuit 13, a wobble signal component is extracted by a BPF circuit 31, the peak value is detected by a wobble peak value detecting circuit 32, a difference between the peak value of the signal Ps and the peal value of the wobble signal component is voltage-divided by a voltage divider 33, the voltage-divided voltage is input to a pre-pit comparator 25 as a slice level, and the push-pull signal Ps is binarized and a pre-pit signal S<SB>LPP</SB>is output. COPYRIGHT: (C)2005,JPO&NCIPI
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