| 摘要 |
PROBLEM TO BE SOLVED: To perform instantly and stably tracking pull-in pulling a light spot in a target track without being affected by a low frequency component of a tracking error signal. SOLUTION: A tracking error signal being position deviation between a light spot and target track is inputted to a low frequency band compensation means 7 and a high frequency band compensation means 6. Output of these low frequency band compensation means 7 and a high frequency band compensation means 6 are added, and a tracking drive signal TRD is generated. Polarity with which the tracking drive signal TRD is half-wave-rectified is switched by a direction detecting means 8, and the tracking drive signal TRD is half- wave-rectified by a half-wave-rectifier 9 with limit voltage in which a signal in which a low frequency component of the tracking drive signal TRD is averaging by an average value processing means 15 is added to offset voltage from a DC power source 10. That is, the tracking drive signal TRD is half-wave- rectified centering a low frequency component. An output of the half wave rectifier 9 is inputted to a drive means 13, and tracking pull-in is instantly and stably performed by obtaining braking power and inputting it to a tracking actuator.
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