| 摘要 |
PROBLEM TO BE SOLVED: To properly cancel a circuit offset and an optical offset occurring in a servo signal. SOLUTION: A focus signal operation amplifier 21 operates a focus signal based on plural output signals from a divided photodetector of an optical pickup to output, and a differential amplifier 24 applies a first system offset cancel voltage: FEOFS-E to the focus signal outputted from the focus signal operation amplifier 21 to output, and a VCA 25 normalizes the focus signal after the first system offset cancel voltage: FEOFS-E is applied with a sum total signal by an AGC control circuit 45 to output, and the differential amplifier 27 applies a second system offset cancel voltage: FEOFS-O to the servo signal after normalized to output.
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