tonya@hpldsla.sid.hp.com (Tony Arnerich) (03/29/91)
Let me start off by apologizing for asking a question that is almost certainly already disposed of in complete detail. But this is the first time I've even seen this group, and... I'd like some more info than I already have about the infrared motion-sensing light switches. What I know is: A) There is one sensor (no "image" is directly sensed) B) A multi-lens plastic panel assures that any moving object overlays many moving images across the sensor area C) The sensor is connected to a circuit that detects time-varying signals What I was told, and cannot believe, is that thermal infrared radiation from a person is the triggering source of IR. I can't believe this because the heat from the detector itself would swamp most input signals. It was claimed that people in thick winter clothing just in from the cold do not trigger these devices. My only "expertise" in this area is a little knowledge of how our IR GC Detector (operating in the "fingerprint" part of the IR spectrum), which needed liquid nitrogen cooling to be able to detect the radiatin from an incandescent source. I assumed the operating principle was that ambient infrared from other light sources reflects off any moving object in the field. Any help from the net in allaying my confusion? tonya@hpldsla.sid.hp.com