| 摘要 |
<p>PROBLEM TO BE SOLVED: To recognize the fact being in an adverse environment and to make an active type infra-red sensor confirmable its non-reportable condition when the sensor is installed in an environment where a noise signal exists, in an active type infra-red sensor detecting subjects (man and the like) invading into a specified area by using infra-red rays pulsed light. SOLUTION: The light receiving sampling timing of a light receiver 3 is at a higher frequency than the frequency of the infra-red pulsed light from a floodlight 2. When the light receiver 3 receives light at a timing other than the timing synchronizing with the frequency of the infra-red pulsed light among each of light receiving sampling timings, a trouble signal is transmitted for informing the sensor 1 of being under the adverse condition where a noise signal, possibly making the sensor unable to report, exists.</p> |
