| 摘要 |
PURPOSE:To minimize the necessary number of connections, and to obtain an eacy-to-see screen, by decreasing the brightness of background video only where character information is superimposed when the character information is displayed while superimposed on part of the television screen. CONSTITUTION:To superimpose character information of a received character broadcast on a usual television screen, a switch 11 is placed normally in an (a)-(b) short-circuit state, or in a (b)-(c) short-circuit state only while primary color signals for character information display are present. To perform said switching, a control signal for the (b)-(c) short-circuit state is supplied to the switch 11 while the output of the brighteness memory in character signal processing circuit 15 is ''1''. Then, the DC level of a video signal for background screen display is controlled to decrease the brightness level of the video signal corresponding to the character information display part, and also to delay primary color signals R, G, and B for character information display by about 0.5mus, thus compensating the delay of signals of a color television tube. |
