| 摘要 |
PURPOSE:To eliminate the disorder of a time base such as a vertical synchronizing disorder at the time of changing-over by making a changing-over circuit which outputs a static picture signal and a usual reproducing video signal after switching these signals to an output side possible to change over only while both signals are synchronized. CONSTITUTION:From a static image signal M outputted from a D/A converting circuit 7, a vertical synchronizing signal (f) is extracted by a synchronizing separating circuit 17, phase-compared with a vertical synchronizing signal C of a reproducing video signal N by a phase comparing circuit 18, and when both phases are made coincident, a reading pulse (e) comes to an L level and the reading of a video RAM 6 is prohibited. A changing-over switch 3 is controlled by the reading pulse (e), only when the reading pulse (e) is at an H level, a changing-over armature 3c is changed over to an input terminal 3b side, and the static image signal M is derived to a monitor 4 instead of the reproducing video signal. Thus, the stable special reproduction without an image disorder can be realized.
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