US4937436A
Expired / Lapsed
US
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Magnetically encoded cards
Assignee: Mars Inc
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Filing: 1989-02-07
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Granted: 1990-06-26
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Expires: 2009-02-07
Abstract
Abstract A magnetically encoded card (2) has a recording track (6, 8) containing data (10, 14, 16, 18) which can be read and re-written by a card reader (30), and a further recording (12) at a much higher spatial bit denisty than the data (10, 14, 16, 18). The high denisty recording (12) is formed using a special write head capable of operating at greater bit densities than the head of the card reader used to write information to the card. The card (2) is deemed valid only if the presence of the high density recording (12) is detected by a read head (34) of the card reader.
Inventors
- 👤 David Eglise
- 👤 Douglas A. Jenkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 00:19
CPC Classifications
G; G07; G07F; G07F7/00; G07F7/08; G07F7/086; G06; G06K; G06K19/00; G06K19/06; G06K19/08; G06K19/10; G06K19/12
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
144 words
A card reader/writer for reading and writing magnetically encoded data from and onto a card, the card having magnetic recording media of predetermined coercivity for storing said data in the form of patterns of magnetic flux transitions which do not exceed a first predetermined spacial density, the reader/writer comprising head means (34, 36) capable of performing said reading and writing, and capable of sensing flux transitions of a second spatial density, substantially greater than said first spatial density, recorded on the card, said head means comprising standard write heads having a maximum data recording rate which does not substantially exceed the first predetermined spacial density, the reader/writer further comprising means (e.g., 66, 68) responsive at least to the sensing of flux transitions of said second spacial density recorded on the card for providing an indication of the validity of data read from the card.
Claim 2
Dependent Claim
144 words
A card reader/writer for reading and writing magnetically encoded data from and onto a card, the card having magnetic recording media of predetermined coercivity for storing said data in the form of patterns of magnetic flux transitions which do not exceed a first predetermined spacial density, the reader/writer comprising head means (34, 36) capable of performing said reading and writing, and capable of sensing flux transitions of a second spatial density, substantially greater than said first spatial density, recorded on the card, said head means comprising standard write heads having a maximum data recording rate which does not substantially exceed the first predetermined spacial density, the reader/writer further comprising means (e.g., 66, 68) responsive at least to the sensing of flux transitions of said second spacial density recorded on the card for providing an indication of the validity of data read from the card.
Claim 3
Dependent Claim
52 words
A card reader/writer as claimed in claim 1, where the head means (34, 36) comprises a single head (34) arranged both to read data in the form of patterns of magnetic flux transitions which do not exceed said first predetermined spatial density and to sense flux transitions of said second spatial density.
Claim 4
Dependent Claim
42 words
A card reader/writer as claimed in claim 2, wherein the head means (34, 36) comprises an additional head (36) for reading and writing data in the form of patterns of magnetic flux transitions which do not exceed said first predetermined spatial density.
Claim 5
Dependent Claim
25 words
A card reader/writer as claimed in claim 3, wherein the heads (34, 36) are arranged to sense flux transitions in respective tracks of the card.
Claim 6
Dependent Claim
56 words
A card reader/writer as claimed in claim 1, wherein the validity indicating means is operable to count pulses from the head means (34, 36) in order to determine whether the spatial density of said magnetic flux transitions is less than said second predetermined density in order to determine whether or not the card (2) is valid.
Claim 7
Dependent Claim
61 words
A card reader/writer as claimed in claim 1, wherein the validity indicating means (66, 68) comprises a frequency to voltage converter (66) responsive to an output of the head means (34, 36), and a comparator (68) for comparing the output of the frequency to voltage converter (66) with a reference voltage in order to determine whether the card (2) is valid.
Claim 8
Dependent Claim
161 words
In combination a card and a card reader/writer system to prevent card duplication fraud, the card having magnetic recording medium (4) of predetermined coercivity for storing data in the form of patterns of magnetic flux transitions which do not exceed a first predetermined spatial density, and further storing flux transitions of a second spatial density which is substantially greater than said first spacial density, the card reader/writer comprising head means (34, 36) for reading and writing magnetically encoded data from and onto the card, and capable of sensing flux transitions of a second spatial density recorded on the card, said head means comprising standard write heads having a maximum data recording rate which does not substantially exceed the first predetermined spacial density, the reader/writer further comprising means (e.g., 66, 68) responsive at least to the sensing of flux transitions of said second spacial density recorded on the card for providing an indication of the validity of data read from the card.
Claim 9
Dependent Claim
161 words
In combination a card and a card reader/writer system to prevent card duplication fraud, the card having magnetic recording medium (4) of predetermined coercivity for storing data in the form of patterns of magnetic flux transitions which do not exceed a first predetermined spatial density, and further storing flux transitions of a second spatial density which is substantially greater than said first spacial density, the card reader/writer comprising head means (34, 36) for reading and writing magnetically encoded data from and onto the card, and capable of sensing flux transitions of a second spatial density recorded on the card, said head means comprising standard write heads having a maximum data recording rate which does not substantially exceed the first predetermined spacial density, the reader/writer further comprising means (e.g., 66, 68) responsive at least to the sensing of flux transitions of said second spacial density recorded on the card for providing an indication of the validity of data read from the card.
Claim 10
Dependent Claim
19 words
The apparatus of claim 7, wherein the second spatial density is not less than 80 flux transitions per mm.
Claim 11
Dependent Claim
19 words
The apparatus of claim 7, wherein the second spatial density is not less than 400 flux transitions per mm.
Claim 12
Dependent Claim
15 words
The apparatus of claim 7, wherein the predetermined coercivity is not greater than 300 oersteds.
Claim 13
Dependent Claim
33 words
The apparatus of claim 7, wherein the data and said magnetic flux transitions of said second spatial density are stored in respective different regions (10, 12, 22, 24, 26, 28) of the card.
Claim 14
Dependent Claim
34 words
The apparatus of claim 11, having a first plurality of regions (10) each containing identical data, and a second plurality of regions (12) each containing the magnetic flux transitions of said second spatial density.
Claim 15
Dependent Claim
33 words
The apparatus of claim 7, wherein the card has a first encodeable track (6) storing the magnetic flux transitions of said second spatial density and a second encodeable track (8) storing said data.
Claim 16
Dependent Claim
24 words
The apparatus of claim 7, the card having an encodeable track (6) storing both data and magnetic flux transitions of said second spatial density.
Claim 17
Dependent Claim
15 words
The apparatus of claim 14, the card having a second track (8) containing additional data.
Claim 18
Dependent Claim
21 words
The apparatus of claim 13, wherein the second track (8) does not contain said flux transitions of the second spatial density.
Claim 19
Independent Claim
187 words
A method of fraud prevention in a system employing a magnetically encoded card having a magnetic recording medium of low coercivity, a card writer for recording high spatial density card validity data on the magnetic recording medium, and a plurality of card reader/writers for reading and writing low density data on the magnetic recording medium of the card, said plurality of card reader/writers lacking the ability to write validity data, comprising the following steps: (a) recording card validity data on the magnetically encoded card with the card writer; (b) recording alterable low density data on the card; (c) providing the plurality of card reader/writers to a general access group; (d) reading the card validity data with one of the plurality of card reader/writers in order to determine the validity of the card; (e) reading the low density data on the card with the card reader/writer; and (f) utilizing the low density data only if the card has been determined to be valid in step (d), whereby fraud is prevented because the plurality of card reader/writers are incapable of writing validity data and therefore cannot duplicate valid cards.
Claim 20
Independent Claim
187 words
A method of fraud prevention in a system employing a magnetically encoded card having a magnetic recording medium of low coercivity, a card writer for recording high spatial density card validity data on the magnetic recording medium, and a plurality of card reader/writers for reading and writing low density data on the magnetic recording medium of the card, said plurality of card reader/writers lacking the ability to write validity data, comprising the following steps: (a) recording card validity data on the magnetically encoded card with the card writer; (b) recording alterable low density data on the card; (c) providing the plurality of card reader/writers to a general access group; (d) reading the card validity data with one of the plurality of card reader/writers in order to determine the validity of the card; (e) reading the low density data on the card with the card reader/writer; and (f) utilizing the low density data only if the card has been determined to be valid in step (d), whereby fraud is prevented because the plurality of card reader/writers are incapable of writing validity data and therefore cannot duplicate valid cards.
Claim 21
Dependent Claim
16 words
The method of claim 17, wherein the magnetic recording medium contains two tracks having encodeable areas.
Claim 22
Dependent Claim
28 words
The method of claim 18, wherein validity data is recorded on the first of said tracks and low density data is recorded on the second of the tracks.
Claim 23
Dependent Claim
32 words
The method of claim 18, wherein validity data is recorded in a first block of the first track and low density data is recorded in a second block of the first track.
Claim 24
Dependent Claim
22 words
The method of claim 18, wherein low density data and validity data are recorded in the same block regions on a track.
Claim 25
Independent Claim
29 words
The method of any one of claims 19, 20 or 21 wherein the density of the flux transitions comprising the validity data is varied according to a predetermined pattern.
Claim 26
Dependent Claim
22 words
The method of claim 17, wherein the validity data has a spatial density of not less than 80 flux transitions per millimeter.
Claim 27
Dependent Claim
22 words
The method of claim 17, wherein the validity data has a spatial density of not less than 400 flux transitions per millimeter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-25 | 1993-12-25 | 1994-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-25 | 1997-12-25 | 1998-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-25 | 2001-12-25 | 2002-06-26 | $7700.00 | Window Closed / Lapsed |