| 摘要 |
<p>PURPOSE:To perform accurate tracking control by releasing the time constant circuit of an envelope detecting circuit from forcible discharging operation when a pilot signal of an adjacent track is sampled and held, and placing the time constant circuit in the forcible discharging operation at other times. CONSTITUTION:When the pilot signal of the adjacent track is sampled and held, the time constant circuit of the envelope detecting circuit 14 is released from the forcible discharging operation and at other times, the time constant circuit is placed in the forcible discharging operation. Therefore, even when the time constant of the time constant circuit is set large, the time constant circuit can be discharged in a short time after envelope detecting operation. Consequently, the time constant of the envelope detecting circuit 14 can be set large and the ripple of an envelope detection output PENV is reduced to improve the tracking of envelope variation. Consequently, the accurate tracking control is performed.</p> |
