Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1990-01-08
1991-06-04
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
340555, G01V 904
Patent
active
050216449
ABSTRACT:
A presence detecting apparatus and method are disclosed, the apparatus including an emitter array and receiver array configured, oriented and shielded to provide an effective detection area characterized by a truncated elliptical footprint, a background compensation network for automatically compensating for variations in environmental conditions in the detection area to provide a substantially constant detection sensitivity, and discriminating circuitry for discriminating signals indicative of a body in the detection area from transient and steady state signals. The emitter circuits and receiving and detecting circuits are capable of asynchronous operation, and the receiver array and detector array are housed so that the receiver array is substantially isolated from selected electromagnetic signals from the detector array.
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Beran Mark A.
Fattahi Farrokh
BC Research and Development, Inc.
Burdick Harold A.
Nelms David C.
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