| 摘要 |
PURPOSE:To produce a normal synchronizing signal in case a normal video signal and therefore a normal synchronizing signal are not obtained, by providing the hardware including a deciding circuit for presence or absence of vertical synchronizing signal, a frequency dividing circuit, etc. CONSTITUTION:A comparator 3 of a synchronizing control signal generating circuit compares the reproduction video sigal sent from a DC reproduction circuit 2 with the comparison voltage to produce a horizontal synchronizing signal. This synchronizing signal is applied to an LPF5 and a 98% gate circuit 4. The LPF5 produces a vertical synchronizing signal which is applied to a deciding circuit 7 for presence or absence of vertical synchronizing signal. The output of the circuit 7 is applied to an AND gate 8 which uses the output of the circuit 4 as an input of one side. The output of the gate 8 is applied to an 1/N divider 9 to deliver an interlacing horizontal synchronizing signal. The vertical synchronizing signal is processed by the comparator 6, a multiplexer 14 which feeds the output of the circuit 7, an odd number deciding circuit 18, other logical circuits, a multiplexer 21, etc. Then a normal vertical control synchronizing signal is delivered to a line 22. |
