| 摘要 |
PURPOSE:To effectively prevent illegal dubbing without affecting a video signal to be displayed. CONSTITUTION:A dubbing prevention signal adding device 3 applies a chroma signal C having an excessive amplitude, for example, 150% amplitude to a position corresponding to the right end part of a horizontal scanning line or the lower end part in the vertical direction of the over scan area placed around the part where the video signal is effectively displayed. Since this dubbing prevention signal DP having the excessive amplitude is placed in the part for insertion of the video signal and is not in the retrace period, it is not eliminated even in the color difference line sequence system and is taken as the object of automatic gain adjustment and limits the amplitude of the following video signal at the time of dubbing. A dark picture is obtained by amplitude limitation when the dubbed effective video signal is reproduced by a video recording and reproducing device 7, and reproducing of this video signal means nothing. |
