Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1979-03-02
1980-12-30
Swann, III, Glen R.
Communications: electrical
Condition responsive indicating system
Specific condition
340527, 340555, 340600, G08B 1308, G08B 1318
Patent
active
042426707
ABSTRACT:
A photosensitive alarm system is provided which produces an alarm signal upon exposure to ambient light for protection of cash drawers, file cabinets, and shipping or storage containers from unauthorized intrusion. The alarm system includes photosensitive arming and trigger circuits which allow the system to become armed when placed in darkness and to be subsequently triggered when exposed to the ambient light. The arming and trigger circuits include separate photocells which are arranged to draw a minimal current to allow a DC battery to be used as a power source for an extended period of time without need for recharging or replacement. Preferably, the alarm system includes a warning circuit capable of producing different output signals in response to multiple exposures of the trigger circuit to the ambient light to indicate the number of intrusions and a clock circuit for indicating the time and date of the initial intrusion into the protected area. Alternatively, the system includes a plurality of intrusion detectors each having a warning circuit which generates unique identification signals to specify the location where the intrusion occurred.
REFERENCES:
patent: 3886352 (1975-05-01), Lai
patent: 3909819 (1975-09-01), Radford
patent: 3930249 (1975-12-01), Steck et al.
patent: 4136968 (1979-08-01), Davis
patent: 4155077 (1979-05-01), Rohan et al.
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