| 摘要 |
PURPOSE:To restrict the deterioration in characteristic and to synthesize a video signal by passing input video signals of three systems through respective gain control circuits and phase adjusting circuits and thereafter synthesizing with newly added two gain control circuits through a changeover circuit. CONSTITUTION:The input video signals are supplied to the gain control circuit 4 through input terminals 1-1, 1-2. The input video signals from input terminals 2-1, 2-2 are supplied to the gain control circuit 5. The output signals of the circuits 4, 5 are respectively supplied to the phase adjusting circuits 7, 8 and the changeover circuits 10, 11, and the output signals of the circuits 10, 11 are supplied to the gain control circuit 16. The input video signals supplied to input terminals 3-1, 3-2 are supplied to the changeover circuits 12, 13 through the gain control circuit 6 and the phase adjusting circuit 9 and the circuits 12, 13 change over the output signals of the circuits 7-9 and the circuits 16 and supply to the gain control circuit 17. The changeover circuits 14, 15 change over the signals of the circuits 7, 8 and the circuit 16. Thus, the deterioration in the characteristic is restricted and the video signal can be synthesized.
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