US3843404A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording coating
Assignee: International Business Machines Corp
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Filing: 1972-09-18
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Granted: 1974-10-22
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Expires: 1992-09-18
Abstract
Abstract 1. A MAGNETIC RECORDING MEDIUM COMPRISING FERROMAGNETIC AND ALUMINA PARTICLES DISPERSED IN A BINDER AS A UNITARY COATING UPON A NON-MAGNETIC SUBSTRATE, EACH OF THE ALUMINA PARTICLES DISPOSED IN SAID BINDER TO BE SUBSTANTIALLY EQUAL TO THE THICKNESS OF THE MEDIUM TO FORM A SOLID BARRIER BETWEEN THE SURFACE OF THE MEDIUM AND THE UNDERLYING NON-MAGNETIC SUBSTRATE AND PRESENT IN AN AMOUNT NOT ABOVE 5% BY WEIGHT OF THE FERROMAGNETIC AND ALUMINA PARTICLES.
Inventors
- 👤 J Haefele
- 👤 C Hawkins
- 👤 R Kubec
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:33
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
72 words
A MAGNETIC RECORDING MEDIUM COMPRISING FERROMAGNETIC AND ALUMINA PARTICLES DISPERSED IN A BINDER AS A UNITARY COATING UPON A NON-MAGNETIC SUBSTRATE, EACH OF THE ALUMINA PARTICLES DISPOSED IN SAID BINDER TO BE SUBSTANTIALLY EQUAL TO THE THICKNESS OF THE MEDIUM TO FORM A SOLID BARRIER BETWEEN THE SURFACE OF THE MEDIUM AND THE UNDERLYING NON-MAGNETIC SUBSTRATE AND PRESENT IN AN AMOUNT NOT ABOVE 5% BY WEIGHT OF THE FERROMAGNETIC AND ALUMINA PARTICLES.
Claim 2
Dependent Claim
72 words
A MAGNETIC RECORDING MEDIUM COMPRISING FERROMAGNETIC AND ALUMINA PARTICLES DISPERSED IN A BINDER AS A UNITARY COATING UPON A NON-MAGNETIC SUBSTRATE, EACH OF THE ALUMINA PARTICLES DISPOSED IN SAID BINDER TO BE SUBSTANTIALLY EQUAL TO THE THICKNESS OF THE MEDIUM TO FORM A SOLID BARRIER BETWEEN THE SURFACE OF THE MEDIUM AND THE UNDERLYING NON-MAGNETIC SUBSTRATE AND PRESENT IN AN AMOUNT NOT ABOVE 5% BY WEIGHT OF THE FERROMAGNETIC AND ALUMINA PARTICLES.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |