| 摘要 |
PROBLEM TO BE SOLVED: To enable detecting surely a wobble signal by canceling a cross talk component of a RF signal with simple and low cost constitution without using an AGC circuit. SOLUTION: A wobble signal is surely detected by a differential amplifier 45 by subtracting a component multiplied by the prescribed gainαbeing in "RF component being added sum signals" = (A+D)+(B+C) from a "push-pull component MPP being a difference signal of light receiving regions A+D, B+C of light receiving elements bisected for a tangential direction of a track " = (A+D)-(B+C), and canceling cross talk of the RF signal. At the time, as the AGC circuit is not used, gain variation is not caused at a recording part boundary part, the wobble signal can be detected stably even at a switching part, also, circuit constitution can be made simple and cost-reduction can be attained. COPYRIGHT: (C)2005,JPO&NCIPI
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