Patent US4673610A successfully refreshed from Google Patents.
US4673610A
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US
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Magnetic recording medium having iron nitride recording layer
Assignee: Fujifilm Holdings Corp
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Filing: 1985-08-20
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Granted: 1987-06-16
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Expires: 2005-08-20
Abstract
Abstract A magnetic recording medium comprises a non-magnetic substrate, a first magnetic film layer which is formed on the non-magnetic substrate and whose major component is cobalt, and a second magnetic film layer which is overlaid on the first magnetic film layer and whose major component is iron nitride.
Inventors
- 👤 Ryuji Shirahata
- 👤 Yoshihiro Arai
- 👤 Tadashi Yasunaga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:30
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/66; G11B5/672; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/26
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
60 words
A magnetic recording medium comprising a non-magnetic substrate, a first magnetic film layer which is formed on the non-magnetic substrate and whose major component is cobalt, and a second magnetic film layer which is overlayed on the first magnetic film layer and whose major component is iron nitride, said first and second magnetic layers being non-binder type magnetic recording films.
Claim 2
Dependent Claim
60 words
A magnetic recording medium comprising a non-magnetic substrate, a first magnetic film layer which is formed on the non-magnetic substrate and whose major component is cobalt, and a second magnetic film layer which is overlayed on the first magnetic film layer and whose major component is iron nitride, said first and second magnetic layers being non-binder type magnetic recording films.
Claim 3
Dependent Claim
25 words
A magnetic recording medium as defined in claim 1 in which said first magnetic film layer contains cobalt by not less than 70 weight %.
Claim 4
Dependent Claim
21 words
A magnetic recording medium as defined in claim 1 in which said first magnetic layer is formed by oblique incidence deposition.
Claim 5
Dependent Claim
24 words
A magnetic recording medium as defined in claim 1 in which said second magnetic film layer contains 5 to 40 atomic % nitrogen atoms.
Claim 6
Dependent Claim
23 words
A magnetic recording medium as defined in claim 1 in which said second magnetic film layer is formed by oblique incidence ion plating.
Claim 7
Dependent Claim
28 words
A magnetic recording medium as defined in claim 1 in which the total thickness of said first and second magnetic film layers is 0.02 μm to 2.0 μm.
Claim 8
Dependent Claim
34 words
A magnetic recording medium as defined in claim 1 in which the ratio of the thickness of said first magnetic film layer to that of the second magnetic film layer is 1:8 to 8:1.
References Cited (Backward Citations)
US3681018A
Cited
US4271232A
Cited
JPS5759304A
Cited
JPS58159240A
Cited
JPS5987809A
Cited
JPS59144043A
Cited
JPS59144034A
Cited
JPS59144037A
Cited
JPS6059537A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-15 | 1990-12-15 | 1991-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-15 | 1994-12-15 | 1995-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-15 | 1998-12-15 | 1999-06-16 | $7700.00 | Window Closed / Lapsed |