| 摘要 |
PROBLEM TO BE SOLVED: To accurately record/reproduce an optical disk even when eccentricity exists therein. SOLUTION: A bit clock signal BC generated by a PLL circuit 20 synchronized with a fine clock mark signal FCM is frequency divided by frequency dividers 204, 38 to be imparted to a phase comparator 42. The phase comparator 42 performs spindle servo control with a CLV(constant linear velocity) system in response to the bit clock signal BC2. A microcomputer 56 switches from ZCAV(zone constant angular velocity) servo control to CLV servo control by the fine clock mark signal FCM at need.
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