Door security system

Details Door security system Door security system

1987-08-06

1989-02-28

Ng, Jin F.

Telephonic communications

Private or single line system

Doorbell system

350243, 350319, 350575, H04M 160

Patent

active

048093203

ABSTRACT:
A security intercommunication system is disclosed which includes an inside housing, an outside housing and a peep-hole optical assembly including a cylindrical body having first and second threadedly engagable, longitudinally aligned sections. The inside housing contains electronic apparatus including an inside speaker/microphone unit, an amplifier having an adjustable input and an output, a battery, an on/off switch and a talk/listen switch. The outside housing contains an outside speaker/microphone unit. Each of the first and second housings are provided with mounting apertures in order that the inside and outside housings may be secured, respectively, on the inside and outside surfaces of the door by passing the sections of the optical assembly cylindrical body through the apertures and into a borehole through the door and screwing the cylindrical body sections together. During the mounting process, a conductor connected to the outside speaker/microphone unit is passed through the borehole to the electronic apparatus situated in the inside housing. The talk/listen switch is incorporated into the electronic apparatus such that when it is in a first position, a person on the inside of the door can hear sounds from the outside of the door picked up by the outside/speaker microphone unit and, when it is in a second position, the person inside the door can speak into the inside speaker/microphone unit whereby the sound is conveyed to the outside speaker/microphone unit.

REFERENCES:
patent: 2169874 (1939-08-01), Hardt
patent: 4130728 (1978-12-01), Grauel
patent: 4269474 (1981-05-01), Kamimura
patent: 4273956 (1981-06-01), Wolfe
patent: 4348083 (1982-09-01), Kamimura
patent: 4584436 (1986-04-01), Boenning et al.

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