Photosensitive alarm systems
First Claim
1. A photosensitive alarm system for detecting unauthorized intrusions into a protected area normally unexposed to ambient light, comprising:
- a photosensitive trigger circuit operable upon exposure of the protected area to ambient light for generating a trigger signal;
a gate circuit coupled to said photosensitive trigger circuit for producing a control signal in response to the said trigger signal;
a warning circuit coupled to said gate circuit for producing an alarm signal in response to said control signal to indicate detection of an intrusion into the protected area; and
a photosensitive arming circuit operable in the absence of ambient light in the protected area for enabling said gate circuit to respond to said trigger signal.
1 Assignment
0 Petitions
Accused Products
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.
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Citations
22 Claims
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1. A photosensitive alarm system for detecting unauthorized intrusions into a protected area normally unexposed to ambient light, comprising:
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a photosensitive trigger circuit operable upon exposure of the protected area to ambient light for generating a trigger signal; a gate circuit coupled to said photosensitive trigger circuit for producing a control signal in response to the said trigger signal; a warning circuit coupled to said gate circuit for producing an alarm signal in response to said control signal to indicate detection of an intrusion into the protected area; and a photosensitive arming circuit operable in the absence of ambient light in the protected area for enabling said gate circuit to respond to said trigger signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A photosensitive alarm system for detecting unauthorized intrusions into a protected area normally unexposed to ambient light, comprising:
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a photosensitive trigger circuit operable upon exposure of the protected area to ambient light for generating a trigger signal; a gate circuit coupled to said photosensitive trigger circuit for producing a control signal in response to said trigger signal; a warning circuit coupled to said gate circuit for producing an alarm signal in response to said control signal to indicate detection of an intrusion into the protected area; and a photosensitive arming circuit operable in the absence of ambient light in the protected area for enabling said photosensitive trigger circuit to generate the trigger signal upon subsequent exposure of said trigger circuit to the ambient light. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification