Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1989-05-13
1990-02-20
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
2503381, 340565, G01V 904, G01J 100
Patent
active
049028871
ABSTRACT:
An optical motion detector detects changes in scene lighting indicative of otion and is also capable of detecting surveillance by active night vision devices using near-infrared light. The detector includes two photodetectors which each provide data to a signal processing network. One photodetector is sensitive to visible light; the other is sensitive to near-infrared light. Both signal processing networks are identical and include a sample-and-hold, a comparator network, and a pulse stretcher. The output of a photodetector is provided to the sample-and-hold and comparator network. The comparator network compares a voltage corresopnding to the instantaneously detected ambient lighting scene with a voltage corresponding to a reference lighting scene. The pulse stretcher receives the output of the comparator network and in turn provides an output to a logical processor. The logical processor compares the outputs of both signal processing networks and provides an output indicating surveillance with near-infrared light. The logical processor also indicates any perturbations in the intensities of incandescent and fluorescent light.
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Allen Stephone B.
Fendelman Harvey
Kagan Michael A.
Keough Thomas Glenn
Nelms David C.
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