| 摘要 |
<p>PURPOSE:To facilitate the program search by recording a signal showing the absence of video signals when only the sound signals are recorded and reproduced and then discriminating said signal in a reproduction mode to control the tape speed. CONSTITUTION:When no video signal exists, the output of a synchronizing separator circuit 6 contains no signal. The presence or absence of video signals is discriminated by the presence or absence of a synchronizing signal. A synchronizing signal detecting circuit 8 switches switching circuits 3 and 9 into the output signal of an inner synchronizing signal generator 7. The output of the switch 9 is supplied to a servo system circuit, and the output of the switch 3 is written on a tape. The synchronizing signal of the generator 7 is defined as a vertical synchronizing signal for example. It is discriminated whether the synchronizing signal sent from a synchronizing separator circuit 15 is equal to a normal or inner simple synchronizing signal in a reproduction mode. Then the discriminated synchronizing signal is sent to a detection circuit 16. The inner simple synchronizing signal undergoes DC conversion through a converter 17 and then the control through a speed control circuit 19 for a normal speed. At the same time, an automatic program search mode is indicated to a terminal 18 to have a program search action only in said search mode. Thus the program is not operated in other modes.</p> |
