| 摘要 |
<p>PURPOSE:To form the stable reproducing picture of a video signal by controlling the tracing positions of two pairs of video heads so as to reduce the swinging volume of the vertical synchronizing signal of a reproducing video signal. CONSTITUTION:Two pairs of the same azimuth video heads A and A', and B and B' are provided at a rotary cylinder 1, and a vertical synchronizing signal (a) obtained by a separator circuit 3 from the reproducing video signal outputted from a video reproducing circuit 2 counts the time width of the vertical synchronizing signal by a latch counter circuit 4 at every period during the section of a gate pulse (b) outputted from a gate signal generator 5, and inputs the maximum value out of all of the counted data in the section to a data comparator 6 as a data (c). The data comparator 6 generates a detecting pulse (d) only when the newly inputted data D2 against the holding D1 is represented as D2>D1, and at the same time, the holding data is replaced from D1 to D2. Therefore, the detecting pulse (d) is outputted from the data comparator 6 and a position control pulse (e) is outputted by a control circuit 9, thereby controlling a capstan motor.</p> |
