| 摘要 |
PURPOSE:To inform surely in real time the invasion to a monitor area without monitoring through a monitor TV at all times, by detecting the invasion to the monitor area according to the changing level of an image signal given from an image means for each prescribed time. CONSTITUTION:The image signals are outputted sequentially from a camera 1 which is image-picking an invasion inhibition area. A still picture extracting circuit 3 grasps the video signals in the form of still pictures of a frame for each prescribed extraction cycle and supplies these picture signals alternately to the 1st and 2nd still picture memories 5 and 7. A comparator 9 for memory contents compares the contents between both memories 5 and 7 in terms of the same memory address. Then the comparator 9 decides the presence of an invader within said inhibition area when the difference of contents is larger than the prescribed value between both memories. Thus the comparator 9 outputs an invader presence signal to an alarm output circuit 11. Then the circuit 11 supplies an alarm signal to an alarm equipment 13 to inform the presence of the invader to a guard, etc.
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