| 摘要 |
PURPOSE:To attain the fully automatic selection of a reading mode, by providing a circuit which shows the history of the video signal written into each field memory and then selecting the field memory to be read out in relation to the output of the above-mentioned circuit and a reference synchronizing signal. CONSTITUTION:A circuit 15 shows the history of the video signal of field memories 3 and 4 respectively. The output of the circuit 15 is supplied to a control circuit 9. Then a control signal of a changeover switch 8 is formed with a history output and a reference synchronizing signal PR. The circuit 15 is provided with counters 16 and 17. The counter 16 is reset by a discriminating pulse PO and performs counting with a PE. So is with the counter 17. The circuit 9 selects a due terminal by discriminating the contents of the counters 16 and 17. In this example, the switch 8 is controlled so as to read out the video signal written into the field memory related to the discriminating pulse supplied to the resetting terminal of a counter which has outputs CO and CE set at (0) respectively. The changeover timing is syncronized with the field period of the signal PR. |
