| 摘要 |
PURPOSE:To obtain a timing pulse excellent in interchangeability by using either a record end pulse which is produced from a desired detection pulse for the drum of a helical scan VTR or a record end pulse that is already recorded, and selecting one of them earlier in terms of time to produce the timing pulse. CONSTITUTION:Presettable counters 30 and 31 are set enable by FF28 and FF29 at a desired time point respectively. The counter 30 is cleared by a drum position detecting pulse PG and counts pulses PG continuously until the set value is obtained. Then the counter 30 delivers a carry signal which shows the starting point of an audio signal. The counter 31 is cleared by said carry signal and outputs the carry signal as a pulse with which production and record are through after counting the drum revolving speed detecting pulses FG up to the set value. Then this pulse which is earlier in terms of time or a record end pulse which is already recorded is turned into a timing pulse for pilot signal through an OR circuit 34. This pilot signal exerts no effect on the audio recording action regardless of the speed and variance of flexibility of a tape. Thus it is possible to obtain a timing pulse which is free from the variance of signal relative positions and excellent in interchangeability. |
