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US 3,988,724 AGranted
Theft alarm
OwnerDavid John Andersoninventor
Life of this patent
Estimating the term…
Abstract
A theft alarm system which includes a transmitter and a receiver which may be fastened together during non-use, with the transmitter being secured to the equipment being protected. Removal of the receiver energizes both the transmitter and receiver. Subsequent movement of the transmitter or attempts to tamper with the transmitter produces a radio frequency signal. The signal is detected in the remote receiver and produces an alarm to alert the person carrying the receiver.
Claims11
A system for detecting the theft of an article comprising
- a transmitter housing securable to said article;
- a transmitter including a battery withn said transmitter housing for transmitting an alarm signal when activated;
- a receiver housing including a radio receiver and battery removeably secured to said transmitter housing;
- a position responsive switch means connected between said transmitter and said battery within said transmitter housing;
- a magnetically activated normally-closed switch means connected between said battery within said transmitter housing and said position responsive switch means;
- and
- magnetic means in said receiver housing for maintaining said magnetically actuated switch means in an open position when said receiver housing is secured to said transmitter housing.
4 more elements
Dependencies are inferred from the claim text.