Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1982-04-16
1985-05-07
Gill, James J.
Communications: electrical
Condition responsive indicating system
Specific condition
G08B 1318
Patent
active
045161151
ABSTRACT:
The present invention provides an improved intrusion detection system of the type in which interruption of a beam of infrared energy transmitted from a transmitter to a receiver generates an alarm signal. The receiver includes a light source which remains unlighted when the transmitter and receiver are properly aligned but will be continuously lighted if either the beam is interrupted or the receiver and transmitter are not aligned. In one aspect of the invention, flasher circuitry in the receiver causes the light source to flash when the transmitted beam is only marginally aligned with the receiver. In another aspect of the invention, a lens in the receiver for focusing infrared radiation on a photodetector is movably mounted and accessible from the outside of the receiver to properly align the transmitted beam with the receiver without dismounting the receiver or requiring the use of any special alignment tools. A cylindrical lens in the transmitter provides a beam having a relatively narrow vertical component to further simplify alignment of the beam with the receiver by eliminating the problem of reflection of the transmitted beam by the ground surface. Accordingly, the improvement of the present invention provides an intrusion detection system in which the transmitted beam can be optimally aligned with the receiver without the use of any extraneous alignment equipment.
REFERENCES:
patent: 3235738 (1966-02-01), Kress et al.
patent: 3390388 (1968-06-01), Kahl, Jr. et al.
patent: 3653021 (1972-03-01), Litman et al.
patent: 3743290 (1973-07-01), Crimmins et al.
patent: 3752978 (1973-08-01), Kahl, Jr. et al.
Frigon Raymond A.
Kahl, Jr. William G.
Cerberus AG
Gill James J.
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