Registers – Coded record sensors – Particular sensor structure
Patent
1995-03-01
1997-03-18
Hajec, Donald T.
Registers
Coded record sensors
Particular sensor structure
360 67, G06K 708
Patent
active
056125283
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of, and apparatus for, reading magnetically encoded information, the apparatus comprising: resonance curve; occuring within the tuned circuit; and encoded information, which verification means comprises means for providing a second signal dependant upon the frequency of signals occurring within the tuned circuit.
Substrates beating magnetically encoded information are increasingly being used, for example, in point-of-sale or automated transaction applications.
A known apparatus of the above general kind is described in our published UK patent number GB 2,035,659. In this apparatus the gapped core and associated coil are held just above and pass over a magnetic stripe. The magnetic stripe comprises alternate sections of permanently aligned ferrous oxide particles interspersed with sections of either differently aligned or randomly oriented ferrous oxide particles. The changes in magnetic permeability of the stripe in the different sections as the core passes over it induce variations in the frequency of the resonant circuit. A signal dependent on this frequency is used to determine whether the stripe under examination is genuine or not.
Whilst the known apparatus operates in an entirely satisfactory manner, a system which offers improved discrimination performance over the prior art is an attractive proposition because of the more widespread use of substrates bearing such magnetically encoded information.
According to one aspect of the present invention an apparatus as defined in the first paragraph is characterized in that in that the verification means further comprises: values representative of signal amplitude and frequency variations occurring within the circuit upon relative movement between the coil and the magnetically encoded information; signal amplitude variations and at least one of the output values representative of signal frequency variations, or functions thereof, with either other output values or known reference values, thereby to obtain a plurality of test values derived from the comparison; and that a positive indication of genuine magnetically encoded information is obtained in dependence upon the combination value having a defined relationship with a predetermined threshold value.
Hence by provision of several test values, all of which must possess certain minimum or maximum requirements, a potentially more secure discrimination system as between genuine and attempted copies of magnetically encoded information than has hitherto been available is provided.
The present invention, in another aspect, provides a method of reading magnetically encoded information including: passing the magnetically encoded information by a gapped magnetic core which has a coil wound thereupon, the coil forming part of a tuned circuit driven at the resonant frequency by an oscillator; and providing a first signal dependent upon the amplitude of signals occurring within the tuned circuit and a second signal dependent upon the frequency of signals occurring within the tuned circuit; characterized by deriving from the first and second signals a plurality of output values representative of signal amplitude and frequency variations produced within the circuit by the passing; comparing at least one of the output values representative of signal amplitude variations and at least one of the output values representative of signal frequency variations, or functions thereof, with either other output values or known reference values, thereby obtaining a plurality of test values; and, combining the test values to provide a combination value, such that a positive indication of genuine magnetically encoded information is obtained in dependence upon the combination value having a defined relationship with a predetermined threshold value.
The present invention will now be described, by way of example only, with reference to the accompanying drawings, of which;
FIG. 1 shows a representation of a known reader of magnetically encoded information;
FIGS. 2(a) and 2(b) illustrate schematical
REFERENCES:
patent: 4328519 (1982-05-01), Way
patent: 4399474 (1983-08-01), Coleman, Jr.
patent: 4593184 (1986-06-01), Bryce et al.
patent: 4617458 (1986-10-01), Bryce
patent: 4749087 (1988-06-01), Buttifant
patent: 5068519 (1991-11-01), Bryce
Green Ian M.
Willcock Simon N. M.
Central Research Laboratories Limited
Hajec Donald T.
Tremblay Mark
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