US3566356A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording document and method
Assignee: 3M Co
•
Filing: 1968-02-29
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Granted: 1971-02-23
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Expires: 1988-02-29
Abstract
Abstract A DOCUMENT SUCH AS A CREDIT CARD OR TRNSPORTATION TICKET HAS A SUBSURFCE MAGNETIC RECORDING MEDIUM FOR ELECTRONIC PROCESSING OF INFORMATION ASSOCIATED WITH USE OF THE DOCUMENT. THE RECORDING MEDIUM EITHER BY ITSELF OR IN A COMPOSITE WITH OTHER MAGNETIZABLE MATERIAL IN THE DOCUMENT HAS AN A.C. DEMAGNETIZATION CURVE OF GRADUAL SLOPE WHICH LENDS ITSELF TO A UNIQUE AND ECONOMICAL TEST FOR VALIDITY AS A SAFEGUARD AGAINST COUNTERFEITING. THE GRADUAL DEMAGNETIZATION CURVE IS CONVENIENTLY ACHIEVED THROUGH THE USE OF MAGNETIZABLE PARTICLES OF TWO DISTINCTLY DIFFERENT COERCIVITIES.
Inventors
- 👤 John D Holm
- 👤 Peter J Vogelgesang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:36
CPC Classifications
G; G06; G06K; G06K19/00; G06K19/06; G06K19/08; G06K19/10; G06K19/12; G07; G07F; G07F7/00; G07F7/08; G07F7/086; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70
Claims Analysis
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References Cited (Backward Citations)
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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) | 1974-02-22 | 1974-08-24 | 1975-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-22 | 1978-08-24 | 1979-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-22 | 1982-08-24 | 1983-02-23 | $7700.00 | Window Closed / Lapsed |