| 摘要 |
PURPOSE:To obtain excellent, easy-to-see character display by removing a character part from a color video signal by a black-and-white signal for character display, adding a color singal for character display to this part, and varying the amplitude values of both the signals in relation to each other. CONSTITUTION:When a color video signal (a) is inputted to a terminal 1 and a black-and-white Y signal (b) for character display is applied from a character broadcast receiving circuit to a terminal 5, an Y' signal (c) appears at an intersection 18, and a signal (d) generated by removing a character part from the video signal (a) appears at an intersection 3. Then, a color signal for character display, e.g., an R signal is applied to a terminal 23 and synthesized with the signal (d) at the intersection 3 through transistors 6 and 7, obtaining a singal (e) at an intersection 8. A peak voltage at the terminal 23 and waveform (c) at the intersection vary with a voltage v0 at the neutral point 10 of a variable resistor 12, and the video signal at the intersection 3 is clamped to the V0 only at the part of a character inverted signal Y like waveform (d). Consequently, the lag of waveform is eliminated and characters are displayed in an easy-to- see state without reference to a background image. |
