| 摘要 |
<p>PURPOSE:To enable the detecting of the existence of an organism accurately in a monitoring zone by comparing with a specified value a difference obtained by the subtraction of a variation of increase or decrease in infrared rays detected from the sum of the variation of the increase. CONSTITUTION:Changes in an infrared detection signal from a thermopile 1 are detected with a differential circuit 8 to be amplified 9 and compared with a reference voltage by a wind comparator 10. When a change signal is above the reference voltage, namely, when a change in infrared rays detected within a monitoring zone 4 is large, a pulse signal is outputted to trigger a one-shot multivibrator (OSMV) 11 and an output signal is maintained for a fixed time during which a man is presumed to move or act. Therefore, when an output signal is generated from the OSMV11 while no man exists in the monitoring zone 4, a man can be determined to invade. A variation of an output signal of a DC amplification circuit 6 is added or subtracted while the output signal from the OSMV11 is generated, and when an absolute value of the resultant total variation falls below a set value, the man is determined to leave the monitoring zone 4.</p> |
