US4661418A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1982-11-04
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Granted: 1987-04-28
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Expires: 2002-11-04
Abstract
Abstract A magnetic recording medium comprising a magnetic recording layer formed on a non-magnetic substrate by depositing a ferromagnetic metal or alloy on the substrate, the recording layer containing oxygen atoms in such a manner that the ratio thereof gradually reduces from the substrate side to the surface of the recording layer except the portion thereof very near to the surface thereof. The recording layer may comprise many deposited magnetic films, each containing oxygen atoms distributed as described above or uniformly in a ratio different from those in the other magnetic films. In the latter case, a magnetic film positioned nearer to the substrate contains a higher ratio of oxygen atoms.
Inventors
- 👤 Akio Yanai
- 👤 Ryuji Shirahata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 02:27
CPC Classifications
H; H01; H01F; H01F41/00; H01F41/14; H01F41/20; G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/658; G11B5/84; G11B5/851; H01F10/00; H01F10/08; H01F10/10; H01F10/26; H01F10/265; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/12; Y10T428/12458; Y10T428/12465; Y10T428/12493; Y10T428/12639; Y10T428/12646; Y10T428/1266; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
73 words
A magnetic recording medium comprising a magnetic recording layer formed on a non-magnetic substrate by depositing a ferromagnetic metal or a ferromagnetic alloy on the substrate, said recording layer containing oxygen atoms in such a manner that the ratio of the oxygen atoms to magnetic metal atoms gradually reduces in the direction from the substrate side to the surface of the recording layer except the portion thereof very near to the surface thereof.
Claim 2
Dependent Claim
73 words
A magnetic recording medium comprising a magnetic recording layer formed on a non-magnetic substrate by depositing a ferromagnetic metal or a ferromagnetic alloy on the substrate, said recording layer containing oxygen atoms in such a manner that the ratio of the oxygen atoms to magnetic metal atoms gradually reduces in the direction from the substrate side to the surface of the recording layer except the portion thereof very near to the surface thereof.
Claim 3
Dependent Claim
21 words
A magnetic recording medium as defined in claim 1 wherein said recording layer is formed by an oblique incidence deposition process.
Claim 4
Dependent Claim
21 words
A magnetic recording medium as defined in claim 1 wherein said recording layer is constituted mainly by cobalt, nickel and oxygen.
Claim 5
Dependent Claim
20 words
A magnetic recording medium as defined in claim 1 wherein said recording layer is constituted mainly by cobalt and oxygen.
Claim 6
Dependent Claim
20 words
A magnetic recording medium as defined in claim 1 wherein said recording layer comprises a plurality of deposited magnetic films.
Claim 7
Dependent Claim
47 words
A magnetic recording medium as defined in claim 5 wherein each deposited magnetic film contains oxygen atoms in such a manner that the ratio of the oxygen atoms gradually reduces in the direction from the side nearer to the substrate to the side farther from the substrate.
Claim 8
Dependent Claim
38 words
A magnetic recording medium as defined in claim 5 wherein oxygen atoms are approximately uniformly distributed in each deposited magnetic film, and a deposited magnetic film positioned nearer to the substrate contains a higher content of oxygen atoms.
Claim 9
Dependent Claim
64 words
A magnetic recording medium as defined in claim 1 wherein the ratio of oxygen atoms to magnetic metal atoms in the vicinity of the substrate is in the range between 10% and 40%, and the ratio in the vicinity of the surface of said recording layer except the portion thereof very near to the surface thereof is in the range between 5% and 20%.
Claim 10
Dependent Claim
57 words
A magnetic recording medium as defined in claim 8 wherein said ratio in the vicinity of the substrate is in the range between 15% and 25%, and said ratio in the vicinity of the surface of said recording layer except the portion thereof very near to the surface thereof is in the range between 5% and 15%.
Claim 11
Dependent Claim
26 words
A magnetic recording medium as defined in claim 1 wherein said recording layer has a thickness within the range between about 0.02 μm and 5.0 μm.
Claim 12
Dependent Claim
26 words
A magnetic recording medium as defined in claim 10 wherein said recording layer has a thickness within the range between about 0.05 μm and 2.0 μm.
References Cited (Backward Citations)
US4239835A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-04-27 | 1990-10-27 | 1991-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-04-27 | 1994-10-27 | 1995-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-04-27 | 1998-10-27 | 1999-04-28 | $7700.00 | Window Closed / Lapsed |