| 摘要 |
PURPOSE:To eliminate the breakdown of a character and a graphic and a color oozing by eliminating a period that inserts the signal of the character and the graphic and chrominance components to a composite video signal. CONSTITUTION:The composite video signal is inputted to a terminal 1 and is separated to a luminance signal and the chrominance components at an isolation circuit 7. The separated luminance signal is supplied to a clipping circuit 3 after clamping by a clamping circuit 2. The base of a transistor Q2 is connected to a voltage source V1 through a switch S1 that is opened/closed by a control signal supplied at terminal 4 and the luminance signal that is clipped only within a period when the terminal 4 is at 'H' level is transmitted to a synthesizing circuit 9. On the other hand, the chrominance component that are separated at the isolation circuit 7 are transmitted to the synthesizing circuit 9 only when the terminal 4 is at 'L' level through a switch 8 that is opened/closed by a control signal supplied at the terminal 4. As stated above, by separating the composite video signal to the luminance signal and the chrominance components and by eliminating the chrominance components during the period that the signal of the character the graphic is inserted to the luminance signal, the breakdown of a part where a white character or the graphic can be seen on a television screen and the color oozing at the vicinity thereof are eliminated.
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