| 摘要 |
PURPOSE:To prevent the runaway of a pickup, by inhibiting the driving control of the pickup owing to a difference between a synchronizing signal detected by the pickup and a reference signal until a prescribed speed is detected for a disk driving motor. CONSTITUTION:The rotational phase of a turntable motor 1 is compared with a reference signal 14 through a phase comparator 15 after detection 12 and amplification 13. Then the phase is compensated 16, and the driving control 17 is given to the motor 1 to obtain synchronism between the rotational phase and the signal 14. When the fact that the disk reaches a prescribed number of revolutions is detected 18 from the output of the comparator 15, a gate signal is fed to a gate 11. While the video signal detected by a pickup 3 is demodulated 6, and the synchronizing signal is separated 7 to be compared with a reference signal input 10 through a comparator 9. Then the difference obtained from the comparison is delivered to the gate 11 to gate the disk if it reaches a prescribed speed. Then the pickup 3 is driven 4. Thus the driving of the pickup 3 is inhibited until the disk reaches its prescribed speed. This can prevent the runaway of the pickup 3. |
