| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate the change of image luminance by non-selected video input signals by respectively providing clamp circuits for first and second composite video input signals and selecting a video channel by a controller. SOLUTION: The first and second composite video signals are respectively connected through capacitors C1 and C2 joined to the clamp circuits 100 and 200 to switches 300 and 400. When a main video is selected by the controller 350, input signals are inputted through the switch 400, an A/D 410, a comb-line filter 420 and a D/A 440 to the switch 500. When an auxiliary channel is selected, the video input signals are inputted through the switch 300, the A/D 310, a digital signal processor 320 and the D/A 340 to the switch 500. The switch 500 sends main and subordinate analog chrominance/analog luminance signals to a processor 600 in response to the controller 350. Thus, the change of the image luminance by the non-selected video input signals is eliminated.</p> |
