| 摘要 |
PURPOSE:To output a halftone signal and to improve discriminative characteristic of a halftone video by providing a half level setting circuit between output terminal of a circuit that clamps tri-color signals and a supply source of reference voltage that determines the clamp level. CONSTITUTION:Tri-color signals S1 from input terminals 1R-1B are added respectively to clamp level circuits 3R-3B. DC level is fixed by reference voltage of a reference voltage supplying circuit 6, and halftone signals outputted by circuits 3R-3B are supplied to halftone switching circuits 5R-5B. Halftone level setting circuits 7R-7G are provided between the output side of circuits 3R- 3B and the circuit 6. A halftone signal VH is formed by circuits 7R-7G and supplied to circuits 5R-5B. The halftone composite signal S5 is added to signal switching circuits 9R-9B, processed by level mixing circuits 12R-12B, and the halftone signal is outputted. |
