Patent US748893A successfully refreshed from Google Patents.
US4774130A
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Magnetic recording medium
Assignee: Proterial Ltd
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Filing: 1985-12-30
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Granted: 1988-09-27
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Expires: 2005-12-30
Abstract
Abstract A magnetic recording medium has a magnetic film formed on the surface of a substrate and a protective film further formed on the surface of the magnetic film. The protective film is composed of a first layer containing at least one substance selected from the group consisting of Cr 2 O 3 , Si, and Ge and a second layer of amorphous carbon or graphite containing amorphous carbon deposited on the front side of the first layer.
Inventors
- 👤 Juro Endo
- 👤 Shiro Murakami
- 👤 Shigeo Fujii
- 👤 Shigeru Oguma
- 👤 Masayuki Nakao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:23
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/726; G11B5/7262; G11B5/7264; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/30; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
92 words
A magnetic recording medium comprising a disc-shaped substrate, a magnetic film formed on the surface of said substrate, and a protective film formed on the surface of said magnetic film, said protective film being composed of a first layer consisting essentially of elemental silicon having a thickness in the range of 100 to 300 Å, and a second layer containing amorphous carbon having a thickness in the range of 200 to 700 Å and a speciic resistance in the range of 10 -3 to 10 4 Ω.cm formed on said first layer.
Claim 2
Dependent Claim
92 words
A magnetic recording medium comprising a disc-shaped substrate, a magnetic film formed on the surface of said substrate, and a protective film formed on the surface of said magnetic film, said protective film being composed of a first layer consisting essentially of elemental silicon having a thickness in the range of 100 to 300 Å, and a second layer containing amorphous carbon having a thickness in the range of 200 to 700 Å and a speciic resistance in the range of 10 -3 to 10 4 Ω.cm formed on said first layer.
Claim 3
Dependent Claim
104 words
A magnetic recording medium comprising a disc-shaped substrate, a magnetic film formed on the surface of said substrate, and a protective film formed on the surface of said magnetic film, said protective film being composed of a first layer containing at least one substance selected from the group consisting of Cr 2 O 3 and Ge having a thickness in the range of 100 to 300 Å, and a second layer containing amorphous carbon having a thickness in the range of 200 to 700 Å and a specific resistance in the range of 10 -3 to 10 4 Ω.cm formed on said first layer.
Claim 4
Dependent Claim
104 words
A magnetic recording medium comprising a disc-shaped substrate, a magnetic film formed on the surface of said substrate, and a protective film formed on the surface of said magnetic film, said protective film being composed of a first layer containing at least one substance selected from the group consisting of Cr 2 O 3 and Ge having a thickness in the range of 100 to 300 Å, and a second layer containing amorphous carbon having a thickness in the range of 200 to 700 Å and a specific resistance in the range of 10 -3 to 10 4 Ω.cm formed on said first layer.
Claim 5
Dependent Claim
35 words
A magnetic recording medium according to claim 2, wherein said second layer is made of amorphous carbon or graphite containing amorphous carbon having specific resistance in the range of 10 -2 to 10 2 Ω.cm.
Claim 6
Dependent Claim
18 words
A magnetic recording medium according to claim 2, wherein said substrate is made of aluminum or aluminum-based alloy.
Claim 7
Dependent Claim
25 words
A magnetic recording medium according to claim 2, wherein said substrate is made of aluminum-based alloy containing not more than 7% by weight of magnesium.
Claim 8
Dependent Claim
31 words
A magnetic recording medium according to claim 2, wherein said magnetic film is made of alloy of one of the compositions of Co-Ni, Co-Ni-Pt, Co Ni-P, Co-Cr, Co-Cr-Pt, Co-Ni-Cr and Co-P.
Claim 9
Dependent Claim
28 words
A magnetic recording medium according to claim 2, wherein said magnetic film is made of Co-Ni alloy containing Ni in a concentration of 5 to 35 at. %.
Claim 10
Dependent Claim
34 words
A magnetic recording medium according to claim 2, wherein said magnetic film is made of Co-Ni-Pt alloy containing 5 to 40 at. % of Ni and not more than 12 at. % of Pt.
Claim 11
Dependent Claim
34 words
A magnetic recording medium according to claim 2, wherein said magnetic film is made of Co-Ni-P alloy containing 5 to 40 at. % of Ni and not more than 12 at. % of P.
Claim 12
Dependent Claim
25 words
A magnetic recording medium according to claim 2, wherein said magnetic film is made of Co-Cr alloy containing 5 to 20 at. % of Cr.
Claim 13
Dependent Claim
33 words
A magnetic recording medium according to claim 2, wherein said magnetic film is made of Co-Cr-Pt alloy containing 5 to 20 at. % of Cr and 1 to 10 at % of Pt.
Claim 14
Dependent Claim
33 words
A magnetic recording medium according to claim 2, wherein said magnetic film is made of Co-Ni-Cr alloy containing 10 to 35 at. % of Ni and 3 to 15 at % of Cr.
Claim 15
Dependent Claim
22 words
A magnetic recording medium according to claim 2, wherein said magnetic film and said protective film are formed by the sputtering technique.
Claim 16
Dependent Claim
25 words
A magnetic recording medium according to claim 4, wherein an undercoating layer harder than said substrate is interposed between said substrate and said magnetic film.
Claim 17
Dependent Claim
34 words
A magnetic recording medium according to claim 2, wherein a layer capable of enabling said magnetic film to adhere with greater fastness to said substrate is interposed between said substrate and said magnetic film.
Claim 18
Dependent Claim
18 words
A magnetic recording medium according to claim 2, wherein a lubricating agent is applied on said protective film.
Claim 19
Dependent Claim
72 words
A magnetic recording medium according to claim 2, wherein said first layer of said protective film is formed of a substance selected from the group consisting of Ge, Cr 2 O 3 , a mixture of Si and Ge, a mixture of Si and Cr 2 O 3 , a mixture of Ge and Cr 2 O 3 , and a mixture of Si and Ge and Cr 2 O 3 .
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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) | 1991-09-27 | 1992-03-28 | 1992-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-09-27 | 1996-03-28 | 1996-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-09-27 | 2000-03-28 | 2000-09-27 | $7700.00 | Window Closed / Lapsed |