Security systems

Details Security systems Security systems

1978-07-10

1980-04-01

Britton, Howard W.

Telecommunications

Receiver or analog modulated signal frequency converter

Signal selection based on frequency

70271, 70DIG51, 340171R, 340171PF, 340172, E05B 4700, H04B 900, H04Q 100

Patent

active

041963474

ABSTRACT:
A door security system includes a lock that is released by an electronic control unit carried on the door and activated by radiation from an r.f. oscillator in a user's key unit. The key unit, provided on a finger ring, includes one or more photovoltaic devices that convert light energy received from a lamp on the door to electrical power for the r.f. oscillator. The r.f. emission may be binary-code modulated and the control unit then includes an appropriate modulation-code detector. The door unit may also include a light-source that emits coded pulses of infra-red light and then the key unit includes a circuit to detect whether the infra-red light received is of the appropriate code-format as a condition for activation of the r.f. oscillator.

REFERENCES:
patent: 3564501 (1971-02-01), Flook
patent: 3801742 (1974-04-01), O'Brien
patent: 3829836 (1974-08-01), Clarke

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