| 摘要 |
PROBLEM TO BE SOLVED: To attain sharp and clear image display by preventing in advance production of noise in a video signal in the ITV(industrial TV) monitor system of multiple earthing structure. SOLUTION: In the ITV monitor system of multiple grounding structure where plural ITV units using a video changeover device to select any of plural ITV cameras are provided to each monitor area, a video input circuit 12 connecting to an output of each ITV unit to select its monitor area has plural video input terminals K1 -K8 arranged electrically insulatingly to the device case are connected in parallel with 1st and 2nd switches P1 -P8 , Q1 -Q8 of relays M1-M8 operated by a control input. Then all the video input terminals K1 -K8 are connected in common to a video output terminal O via make contacts of the 1st and 2nd switches P1 -P8 , Q1 -Q8 , and break contacts are connected via input resistors R1 -R8 to be floated. |
