DROP-OUT DETECTING CIRCUIT

PURPOSE:To detect correctly a drop-out at a place near the front edge of a vertical synchronizing pulse of a video signal which causes the flicker on a screen, by producing a marker signal from a vertical synchronizing signal preceding by a cycle (a field) and using said marker signal to gate a drop...

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1. Verfasser: YOSHIKAWA HIROYOSHI
Format: Patent
Sprache:eng
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Zusammenfassung:PURPOSE:To detect correctly a drop-out at a place near the front edge of a vertical synchronizing pulse of a video signal which causes the flicker on a screen, by producing a marker signal from a vertical synchronizing signal preceding by a cycle (a field) and using said marker signal to gate a drop-out detecting signal. CONSTITUTION:A vertical synchronizing signal V.SYNC is supplied to a terminal 10 from a reproducer 1; while a drop-out pulse, i.e., a correction signal is supplied to a terminal 11 from the reproducer 1 respectively. Then the signal V. SYNC is supplied to a mask signal generating circuit 12 and a noise filter 13. The circuit 12 has the phase synchronization with the signal V.SYNC and delivers a signal having the pulse width of a period including the period of said vertical synchronizing signal, especially a place near the front edge. An output signal (b) is supplied to the filter 13, and the noise of the signal V.SYNC is eliminated through the filter 13. This prevents a malfunction of a drop-out detecting circuit.