| 摘要 |
PURPOSE:To suppress the occurrence of abnormal operation when eccentricity is large, and to improve the effect by limit of excessive movement of an actuator, by providing a filter or a trap suppressing a disc rotating frequency component for a jitter servo circuit. CONSTITUTION:When the eccentricity of a disc is large and a rotating frequency component of a large amplitude is produced at a feedback terminal 6, the component is attenuated with a trap circuit 10 suppressing a rotating shaft frequency 30Hz component and given to an output of an amplifier 8. The output of the amplifier 8 hardly exceeds the threshold value of diodes 9a, 9b, allowing to suppress the generation of abnormal phenomenon due to the large eccentricity. |
