US4543301A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Sony Corp
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Filing: 1983-08-10
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Granted: 1985-09-24
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Expires: 2003-08-10
Abstract
Abstract A magnetic recording medium having a non-magnetic substrate on which a first bismuth Bi under layer, a first magnetic metal layer, a compound layer made of the magnetic metal, a second bismuth Bi under layer and a second magnetic metal layer are sequentially formed in this order.
Inventors
- 👤 Kenji Yazawa
- 👤 Kenichi Baba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:01
CPC Classifications
H; H01; H01F; H01F41/00; H01F41/32; H01F41/34; G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/66; G11B5/676; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12632; Y10T428/12681; Y10T428/12771; Y10T428/12861; Y10T428/12931; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
78 words
A magnetic recording medium comprising: a non-magnetic substrate; a first bismuth under layer formed on said non-magnetic substrate; a first magnetic metal layer formed on said first bismuth under layer; a compound layer composed of a compound of the metal of said first magnetic layer formed on a surface portion of said magnetic metal layer; a second bismuth under layer formed on said compound layer; and a second magnetic metal layer formed on said second bismuth under layer.
Claim 2
Dependent Claim
78 words
A magnetic recording medium comprising: a non-magnetic substrate; a first bismuth under layer formed on said non-magnetic substrate; a first magnetic metal layer formed on said first bismuth under layer; a compound layer composed of a compound of the metal of said first magnetic layer formed on a surface portion of said magnetic metal layer; a second bismuth under layer formed on said compound layer; and a second magnetic metal layer formed on said second bismuth under layer.
Claim 3
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said bismuth under layer has a thickness in a range from 10 to 1000 Å.
Claim 4
Dependent Claim
17 words
A magnetic recording medium according to claim 1, wherein said magnetic metal is cobalt or cobalt-nickel alloy.
Claim 5
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said magnetic metal layer has a thickness in a range from 100 to 1000 Å.
Claim 6
Dependent Claim
30 words
A magnetic recording medium according to claim 1 which further comprises an amorphous layer of silicon or silicon compound provided between said non-magnetic substrate and said first bismuth under layer.
Claim 7
Dependent Claim
19 words
A magnetic recording medium according to claim 1, wherein said bismuth under layer is formed as a discontinuous layer.
Claim 8
Dependent Claim
18 words
A magnetic recording medium according to claim 1, wherein said compound is an oxide of said magnetic metal.
Claim 9
Dependent Claim
127 words
A magnetic recording medium comprising: a non-magnetic substrate; a first bismuth under layer formed on said non-magnetic substrate; a first magnetic metal layer formed on said bismuth under layer by vapor deposition in which the angle of incidence of a vapor of said magnetic metal is substantially normal to a surface of said substrate; a compound layer composed of a compound of the metal of said first magnetic metal formed on a surface portion of said magnetic metal layer; a second bismuth under layer formed on said compound layer; and a second magnetic metal layer formed on said second bismuth under layer by vapor deposition in which the angle of incidence of a vapor of said magnetic metal is substantially normal to the surface of said substrate.
Claim 10
Dependent Claim
127 words
A magnetic recording medium comprising: a non-magnetic substrate; a first bismuth under layer formed on said non-magnetic substrate; a first magnetic metal layer formed on said bismuth under layer by vapor deposition in which the angle of incidence of a vapor of said magnetic metal is substantially normal to a surface of said substrate; a compound layer composed of a compound of the metal of said first magnetic metal formed on a surface portion of said magnetic metal layer; a second bismuth under layer formed on said compound layer; and a second magnetic metal layer formed on said second bismuth under layer by vapor deposition in which the angle of incidence of a vapor of said magnetic metal is substantially normal to the surface of said substrate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-09-23 | 1989-03-25 | 1989-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-23 | 1993-03-25 | 1993-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-23 | 1997-03-25 | 1997-09-24 | $7700.00 | Window Closed / Lapsed |