Infrared intrusion detector

Details Infrared intrusion detector Infrared intrusion detector

1986-05-19

1988-04-26

Howell, Janice A.

Radiant energy

Invisible radiant energy responsive electric signalling

Infrared responsive

250353, 350433, 350452, G01J 508, G02B 302

Patent

active

047407018

ABSTRACT:
An intrusion detector evaluates the infrared radiation emitted by an intruder within a closely defined zone or area by means of a virtual protective curtain. Uniform sensitivity independent of incident angle of the radiation is provided by a cylindrical Fresnel lens of small thickness, which divides the field of reception into sharply defined strips or elongate zones of substantially uniform sensitivity. The longitudinal axis of this Fresnel lens defines an arcuate sector of a circle whose radius is determined by the focal length in perpendicular direction, and an infrared sensor is arranged at the circular center point, i.e., the focal point of the curved Fresnel lens. One particularly advantageous embodiment of the intrusion detector includes a double sensor configuration, equipped with several sensor elements cooperating with one or more cylindrical Fresnel lenses, thus covering a number of separate zones for simultaneous radiation detection.

REFERENCES:
patent: 3703718 (1972-11-01), Berman
patent: 4058726 (1977-11-01), Paschedag et al.
patent: 4318089 (1982-03-01), Frankel et al.
patent: 4321594 (1982-03-01), Galvin et al.
patent: 4339748 (1982-07-01), Guscott et al.
patent: 4375034 (1983-02-01), Guscott
patent: 4385808 (1983-05-01), Vanderwerf
patent: 4523095 (1985-06-01), Keller-Steinbach
patent: 4545366 (1985-10-01), O'Neill

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