| 摘要 |
<p>PURPOSE:To prevent the erroneous detection of a synchronizing signal, and to attain a stable tracking control by outputting a signal corresponding to a reproducing synchronizing signal only when the shift of half period width of a reproducing ATF synchronizing signal is within a prescribed quantity, in an area division automatic track follow-up (ATF) controller. CONSTITUTION:A reproducing ATF synchronizing signal detected by a BPF 12, a comparator 13, and a pattern detecting circuit 24 is supplied, a counter 17 counts a clock for a half period of the reproducing ATF synchronizing signal, and a comparator 19 decides whether the reproducing ATF synchronizing signal is correct or not in accordance with whether the shift of width of the half period of the reproducing ATF synchronizing signal is within the prescribed value or not. An SPL1 forming circuit 21 which is controlled by the comparator 19 generates and outputs a timing signal for holding a reproducing pilot signal in accordance with the reproducing ATF synchronizing signal, only when its signal is correct. In such a way, the erroneous detection of the reproducing ATF synchronizing signal is prevented, and a stable ATF control is executed.</p> |
