| 摘要 |
PURPOSE:To improve the monitoring precision through regular monitoring while reducing the labors of a person in charge of monitoring, by previously storing the normal video pattern of a screen for the regular monitoring and then by automatically checking this video pattern and current video pattern. CONSTITUTION:Television cameras 6-8 are provided and video signals from those cameras 6-8 are changed over by selecting circuit 2 at intervals of a constant period. The selected video signal is supplied to monitor TV1, VTR device 16 and change detection part 11 via signal line 9. Then, the information on which of cameras 6-8 has been selected is sent from selecting circuit 2 to detection part 11 via signal line 10 to compare a video pattern in normal operation with the current supplied video pattern. When an abnormal change is judged on the basis of the comparison result, information on the fault is outputted to signal line 14, and buzzer 15 is put into operation to let a person in charge of the monitoring know that, so that the monitoring precision may be improved through the regular monitoring while the labors of the person in charge of the monitoring are reduced. |
