| 摘要 |
PURPOSE:To avoid the disturbance of a reproduced picture even if the recording is restarted at the middle of a track by making the preceding and next record synchronizing signals accurately coincident to the same revolving angle position of a disk. CONSTITUTION:The output voltage of a comparator 31 for frame synchronous phase is superposed on the voltage of a speed detection signal and then used for the input of a motor driving circuit 12. Then the control is given so as to obtain the coincidence of phase between a frame synchronous reference signal and a revolving position detecting signal. Thus a synchronism detecting signal is obtained from a synchronism detecting circuit 43 when a slight moment elapses from the start of a motor 3. Then switch circuits 21 and 23 are turned off and on respectively. Therefore the stabilized voltage is supplied to the circuit 12 from a stabilized voltage supply circuit 22 in place of the speed detection voltage. As a result, the control disturbance of the motor is not substantially produced despite switching of the circuits 21 and 23. |
