US4237189A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polymodal magnetic recording media process for making and verifying the same and compositions useful therein
Assignee: Carlisle Memory Products Group Inc
•
Filing: 1973-10-31
•
Granted: 1980-12-02
•
Expires: 1993-10-31
Abstract
Abstract Polymodal magnetic information-recording articles formed with at least two different populations of magnetic powders, whereby at least one of the powders, being of lower intrinsic coercivity and forming means to accept a noise interference pattern, accepts a pattern which serves as a means to verify the authenticity or detect previous tampering with the magnetic recording device. More generally, the disclosure relates to polymodal recording media characterized by incorporation of a plurality of independently - erasable ferromagnetic powder populations and processes for making and using said media.
Inventors
- 👤 Robert J. Deffeyes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 16:26
CPC Classifications
G; G06; G06K; G06K19/00; G06K19/02; B; B32; B32B; B32B27/00; B32B27/14; G06K19/06; G06K19/08; G06K19/10; G06K19/12; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716; B32B2264/00; B32B2264/10; B32B2264/102; B32B2307/00; B32B2307/20; B32B2307/206; B32B2425/00; G11B23/00; G11B23/28; G11B23/283; G11B23/284; G11B23/30; G11B23/34; G11B23/38; G11B23/40; G11B5/74; G11B5/78; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
130 words
In an article comprising a ferromagnetic composition adapted to be processed in a magnetic field to receive a pattern which pattern can be sensed by a magnetic reading head, the improvement wherein said ferromagnetic composition comprises at least two different populations of ferromagnetic material intermixed within a matrix, each of said populations forming means to store, independently from one another, magnetically-recorded information and wherein a first said population is so selected that it can be magnetically switched at a magnetic field intensity at which a second said population of said composition is not affected and wherein a non integrated dM/dt curve of the magnetic populations will exhibit a valley between two adjacent peaks equal to at least one-half the average distance from the base line to top of said peaks.
Claim 2
Dependent Claim
130 words
In an article comprising a ferromagnetic composition adapted to be processed in a magnetic field to receive a pattern which pattern can be sensed by a magnetic reading head, the improvement wherein said ferromagnetic composition comprises at least two different populations of ferromagnetic material intermixed within a matrix, each of said populations forming means to store, independently from one another, magnetically-recorded information and wherein a first said population is so selected that it can be magnetically switched at a magnetic field intensity at which a second said population of said composition is not affected and wherein a non integrated dM/dt curve of the magnetic populations will exhibit a valley between two adjacent peaks equal to at least one-half the average distance from the base line to top of said peaks.
Claim 3
Dependent Claim
18 words
An article as defined in claim 1 wherein at least one said ferromagnetic material is a metal powder.
Claim 4
Dependent Claim
29 words
An article as defined in claim 2 wherein said coercivity of the first population is below about 400 and the coercivity of said second population is above about 600.
Claim 5
Dependent Claim
20 words
An article as defined in claim 2 wherein said first population is selected from iron-oxide powder or chromium oxide powder.
Claim 6
Dependent Claim
21 words
Article as defined in claim 4 wherein the Bm value of at least one said ferromagnetic material is above 8,000 gauss.
Claim 7
Dependent Claim
29 words
An article as defined in claim 1 wherein said coercivity of the first population is below about 400 and the coercivity of said second population is above about 600.
Claim 8
Dependent Claim
21 words
Article as defined in claim 6 wherein the Bm value of at least one said ferromagnetic material is above 8,000 gauss.
Claim 9
Dependent Claim
20 words
An article as defied in claim 1 wherein said first population is selected from iron-oxide powder or chromium oxide powder.
Claim 10
Dependent Claim
21 words
Article as defined in claim 8 wherein the Bm value of at least one said ferromagnetic material is above 8,000 gauss.
Claim 11
Dependent Claim
35 words
An article as defined in claim 8 wherein there is a third population of ferromagnetic material that can be either switched or erased without substantial effect on either of the first or second said populations.
Claim 12
Dependent Claim
21 words
Article as defined in claim 1 wherein the Bm value of at least one said ferromagnetic material is above 8,000 gauss.
Claim 13
Dependent Claim
35 words
An article as defined in claim 11 wherein there is a third population of ferromagnetic material that can be either switched or erased without substantial effect on either of the first or second said populations.
Claim 14
Dependent Claim
35 words
An article as defined in claim 1 wherein there is a third population of ferromagnetic material that can be either switched or erased without substantial effect on either of the first or second said populations.
Claim 15
Dependent Claim
42 words
A polymodal magnetic recording member comprising two different ferromagnetic compositions, said composition distinguished by a difference of at least 200 in coercive force between the ferromagnetic components thereof, and wherein said compositions are separated by a spacing element formed of polymeric film.
Claim 16
Dependent Claim
42 words
A polymodal magnetic recording member comprising two different ferromagnetic compositions, said composition distinguished by a difference of at least 200 in coercive force between the ferromagnetic components thereof, and wherein said compositions are separated by a spacing element formed of polymeric film.
Claim 17
Dependent Claim
19 words
An article as defined in claim 1 wherein said ferromagnetic component is mounted on the surface of said article.
References Cited (Backward Citations)
US2694656A
Cited
US3149996A
Cited
US3219353A
Cited
US3328195A
Cited
US3740266A
Cited
US3689317A
Cited
US3725126A
Cited
US3653962A
Cited
US3767464A
Cited
US3761311A
Cited
US3775178A
Cited
US3790754A
Cited
DE2403401A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |