| 摘要 |
<p>PURPOSE:To produce an editing timing pulse through a simple constitution, by deciding the editing timing of a video signal recorder with the output of a counter that produces the reference signal of a phase servo circuit. CONSTITUTION:The rotary phase detection signal PG of a head drum is supplied to the set input of an FF12 via a monostable multivibrator 9, and the reference vertical synchronous signal X-VD is supplied to the reset input. Thus a phase difference pulse DPEB is delivered of Q. The external vertical synchronous signal EXTVD is supplied to the reset input R of an internal synchronous signal counter 24 via a differentiating circuit 26 and an OR gate G5. At the same time, the output of the counter 24 is supplied to a decoder 27 to produce a reset pulse (e) having the 1/2 vertical scanning period. This reset pulse is fed back to the reset input of the counter 24. Accordingly, the counter 24 is reset with the reset pulses (e) and d. The phase servo system is locked by the signal X-VD which is produced with a delay of a prescribed time from the reset position. Thus a certain synchronous relation is kept between the pule PG and the signal EXTVD.</p> |
