Communications: electrical – Digital comparator systems
340149R, 340147MD, H04G 300
An access control system for controlling and monitoring access to selected restricted areas and "alarm" conditions at such areas. The system comprises a central controller unit which repeatedly polls a number of remotely located reader terminals and alarm monitors. The reader terminals are adapted to receive and "read" magnetically encoded card keys issued to personnel and to sense "alarm" conditions at such areas. When a card key which has a proper facility code on it, is inserted into a card activated lock, a card reader at a reader terminal determines whether the card key is magnetically encoded so as to meet all entrance criteria stored in a memory of the central controller. If the card is properly encoded, access is granted to the cardholder at that location. If the card key does not have the proper facility code or does not meet the entrance criteria stored in the memory system of the central controller, access is denied and an alarm condition may be generated at the central controller to alert the person or persons monitoring the system. Alarm signals (e.g., fire, smoke, etc.) may also be transmitted to the central controller via any given reader terminal.
The central controller is programmed to provide a number of different access levels and time zones for controlling access of card holders at selected locations and times of day. Programming is also provided for operation of various peripheral equipment in the system.
A number of optional features are provided for expanding the capabilites of the system of the present invention and enhancing its advantages.
One such optional feature prevents a cardholder from passing his card back to another (unauthorized) person after the cardholder has entered the restricted area. This optional feature may also be used to determine and indicate whether a particular cardholder is on or off the premises.
Also optionally provided is a printer for interfacing with the controller to provide hard copies of all transactions and parameters and to list parameters recalled from the memory unit in the central controller of the system.
Other optional peripheral equipment is provided for simplifying installation of the system and enabling operation of reader terminals at relatively long distances from the central controller.
Terminal expanders may be used to simplify cabling requirements. Cables from a number (e.g., 16) of reader terminals may be connected to a terminal expander from which only a single cable is run to the central controller.
Modems may be used in the system to enable reader terminals to be operated at virtually unlimited distances from the central controller through telephone lines.
When the access control system of the present invention is initially installed, the central controller is programmed with all necessary parameters for all authorized card keys, reader terminals and alarm monitors.
patent: 3821704 (1974-06-01), Sabsay
patent: 3833885 (1974-09-01), Baump
patent: 3845277 (1974-10-01), Voss
patent: 3906447 (1975-09-01), Crafton
patent: 3931497 (1976-01-01), Gentile
patent: 3937925 (1976-02-01), Boothroyd
patent: 3956615 (1976-05-01), Anderson
Baump Paul A.
Sain Jerry T.
Zbriger Richard A.
Gardner Paul L.
Greer Hydraulics, Inc.
Pitts Harold I.
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