US 5,288,981 AGranted

Method and apparatus for encoding machine readable serial encryptedmagnetic data

AssigneeAllsafe Company, Inc.

InventorMichael L. Davis

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Abstract

The present invention provides a method and apparatus for encoding and detecting data from magnetically encoded access cards. The invention includes a control unit (1) having an access card slot (4) communicating with a microprocessor (11) and sensor (3). A barium ferrite access card (5) magnetically encoded in a particular grid pattern is interposed within the card slot, and the encoded grid pattern is then detected and "read" by the sensor. The encoded data in grid form is then transmitted to the microprocessor which, in turn, assigns to the magnetically encoded grid representation a numeric value. This numeric value is then compared with a list of values stored in the microprocessor and if the detected and translated numeric value corresponds to a stored value, the microprocessor, directly or indirectly, emits a signal to activate or deactivate a device to be controlled (10).

Claims22

Dependent claims

In an electronic access system having one or more sensors for detecting magnetically encoded data represented on control cards and a programmable microprocessor for transforming said detected encoded data into useable data or concomitant commands, the method of encoding and detecting said access card data comprising the steps of:

providing an access card having a substantially planar surface with a layer of magnetic media, said access card adapted to be selectively magnetized along said magnetic layer of said planar surface;
providing a grid on said access card having a plurality of rows and columns, said grid having defined points at the intersection of said rows and columns, each of said grid points adapted to be selectively magnetized;
providing a sentinel point at either end of said access card, said sentinel point adapted to be magnetized and positioned in advance of said grid directly above one of said rows;
magnetizing said sentinel;
selectively assigning to each of said grid points, except those in the row containing said sentinel, a numeric value represented in a number base equal to the total number of rows in said grid;
selectively magnetizing said pre-selected grid points such that said detected magnetic points equal a pre-selected numeric value;
whereby, said sensors are adapted to detect said series of magnetic grid points upon detecting said sentinel and transferring rows and column position of said detected magnetic points to said microprocessor, wherein said microprocessor is programmed to transform said information into numeric data in response thereto.

4 more elements

An access control device for controlling a second device comprising:

a main control unit having a programmable microprocessor with memory contained therein, said microprocessor communicating with said second device to be controlled and adapted to receive and decode magnetic data into command signals directed to the operation of said second device;
an access card slot, interposed within said control unit, having one or more openings for access outside of said control unit, said card slot adapted to slidably receive a substantially planar card therein;
an access control card having top and bottom substantially planar surfaces configured to be slidably received within said card slot, said control card further adapted to be magnetized with pre-selected polarity at pre-selected points along a magnetic grid comprising rows and columns interposed on said top and bottom surfaces of said control card;
a magnetized sentinel point, operatively positioned at an end of said access card adjacent to said grid and directly above a pre-selected row or rows of said grid;
grid matrices, electronically stored in said microprocessor memory, said grid matrices comprising a series of numeric values corresponding to each point in said access card magnetic grid, said numeric values being dependent upon the position of said sentinel point and said polarity;
sensing means operatively arranged within said card slot and adapted to detect the presence of said sentinel or sentinels and to recognize the presence and order of said magnetized grid points thereafter, said sensing means further operatively arranged to communicate the order and position of said sentinel and said detected magnetized grid points to said microprocessor;
whereby said magnetic information is detected by said sensor from said access card and transmitted to said microprocessor where said information is decoded into a numeric value and attendant command signal.

4 more elements

Dependencies are inferred from the claim text.