TIMING PULSE GENERATING CIRCUIT

PURPOSE:To simplify the circuit and to improve the stability and precision by controlling the start of counting with a vertical synchronizing signal, counting a horizontal synchronizing signal and comparing the counted horizontal synchronizing signal with a horizontal line set externally, and outputting a timing pulse when they coincide with each other. CONSTITUTION:When a composite video signal (a) is inputted from a composite video signal input 2, a synchronous separating circuit 3 separates and outputs its synchronizing signal. Therefore, the synchronizing signal is inputted to a horizontal synchronizing signal generating circuit 4 and a vertical synchronizing signal generating circuit 5 to generate a horizontal synchronizing signal (e) and a vertical synchronizing signal (d). A monostable multivibrator circuit 6 expands the vertical synchronizing signal (d) like a signal (g). A counter 7 starts counting the horizontal synchronizing signal (e) after the signal (g) is outputted and supplies the result to a comparator 8. The comparator 8 compares the count signal with the horizontal line set with a line setting signal from a line setting signal input 1 and outputs the timing pulse signal (h) for the horizontal line when they coincide with each other.