JPS6424575A - Circuit for providing special effect on video signal - Google Patents

Abstract

PURPOSE:To confirm to which extent a special effect is obtained by providing a first counter coupled at a horizontal synchronizing separating circuit and a second counter coupled at a vertical synchronizing separating circuit. CONSTITUTION:The titled circuit has a first counter 23 to output a pulse for 1/n of one horizontal scanning period and a second counter 27 to output the pulse for 1/m of one vertical scanning period. When a special effect mode is commanded by an instructing circuit 3, the signal, in which the low order number bit of a D/A converter 2 is made into an input prohibition, the resolution is reduced and the screen is made into the special effect, is sent to a gate circuit 5. First and second counters 23 and 27 are respectively resetted by horizontal and vertical synchronizing signals (a) and a' and its own counting-up output from horizontal and vertical synchronizing separating circuits 20 and 21 and the pulse signal is outputted for a constant period. By the outputs of the first and second counters 23 and 27, the output of first and second flip flop circuits 24 and 28 is alternately inverted. The output of an exclusive OR 25 of these outputs is sent to the gate circuit 6. Thus, the signal can be made diced and it can be easily confirmed to which extent the special effect is applied.