| 摘要 |
PROBLEM TO BE SOLVED: To lower the loop gain of a tracking loop by detecting disturbance of a tracking error signal caused by a medium defect which is not detected by conventional detection of degrading of total light quantity. SOLUTION: In an optical disk recording and reproducing device, an arithmetic processor calculates (steps S1 to S3) operation quantity data on a tracking actuator for making a light beam spot follow a track for scanning on the basis of the tracking error signal TE. Subsequently, the arithmetic processor 9 lowers (steps S5 and S6) the loop gain of a tracking control loop when a gain down flag is "1", (during track scanning of a previously set optical disk rotary angle position including an optical disk rotary angle position where the appearance of disturbance of the tracking error sinal is predicted), that is in a period "1" in which the reliability of the tracking error signal is low in step S7. Thereby, response to the disturbance of the tracking error sinal is lowered to avoid off-tracking. COPYRIGHT: (C)2009,JPO&INPIT
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