| 摘要 |
<p>An apparatus for removing ghost images includes a transversal filter which is provided with signal delay circuits (8), (11); weighting circuits (91) to (9n), (121) to (12m) each connected to taps of the signal delay circuits (8), (11); demultiplexer delay circuits (19), (20); and switching circuits (211) to (21n), (221) to (22m) and memory circuits (241) to (24n), (251) to (25m) which are connected between taps of the demultiplexer delay circuits (19), (20) and corresponding weighting circuits (91) to (9n), (121) to (12m). The transversal filter is connected to a video signal source (4), and forms a ghost-exorcising signal which is output to a synthesizer circuit (6) where it is combined with a video signal from the video signal source (4). In addition, a circuit is provided which detects at least the ghost level in the video signal from the synthesizer circuit (6) during a predetermined period after a reference time, and the output of the detector circuit is supplied to the demultiplexer delay circuits. The ghost-level detector circuit is provided with a circuit (35) which forms masking pulses including the reference time, a circuit (36) which detects the reference time from the masking pulses, a circuit (15) which forms a standard waveform from the output of the reference time detector circuit (36), a circuit (13) which substracts the standard waveform from the video signal from the synthesizer circuit (6), and a circuit (17) which detects the ghost level from the output of the subtracter circuit (13). A signal indicating the detection of the leading edge of each masking pulse is supplied to the demultiplexer delay circuits (19), (20) as a pilot pulse. The pilot pulse is detected from that signal passing through the demultiplexer delay circuits (19), (20), and the operations of the switching circuits (211) to (21n), (221) to (22m) are controlled on the basis of the thus-detected signal. The apparatus makes it possible to provide excellent weighting with a simple construction. </p> |
