Patent US4539265A successfully refreshed from Google Patents.
US4539265A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Sony Corp
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Filing: 1983-10-11
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Granted: 1985-09-03
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Expires: 2003-10-11
Abstract
Abstract A magnetic recording medium is disclosed which includes a non-magnetic substrate, a first layer made of bismuth formed on the substrate in a discontinuous island shape, and a ferromagnetic metal layer formed over the first layer and the substrates and also a magnetic recording medium is disclosed which includes a non-magnetic substrate, a first layer formed continuously covering the substrate made of amorphous silicon and/or silicon compound, a second layer made of bismuth formed on the substrate in a discontinuous island shape and a ferromagnetic metal layer formed over the first and second layers.
Inventors
- 👤 Kenji Yazawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:42
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/656; G11B5/84; G11B5/851; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12771; Y10T428/12861; Y10T428/12931; Y10T428/24; Y10T428/24479; Y10T428/24521; Y10T428/24802; Y10T428/24917; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
68 words
A magnetic recording medium comprising: a non-magnetic substrate; a first layer made of bismuth having a thickness of from 10 to 1000 Angstroms formed on said substrate in a discontinuous island shape; and a ferromagnetic metal layer having a thickness of from 100 to 1000 Angstroms formed over said first layer and said substrate, said medium having isotropic magnetic characteristics in the plane of the ferromagnetic metal layer.
Claim 2
Dependent Claim
68 words
A magnetic recording medium comprising: a non-magnetic substrate; a first layer made of bismuth having a thickness of from 10 to 1000 Angstroms formed on said substrate in a discontinuous island shape; and a ferromagnetic metal layer having a thickness of from 100 to 1000 Angstroms formed over said first layer and said substrate, said medium having isotropic magnetic characteristics in the plane of the ferromagnetic metal layer.
Claim 3
Dependent Claim
90 words
A magnetic recording medium comprising: a non-magnetic substrate; a first layer formed continuously covering said substrate made of amorphous silicon and/or silicon compound having a thickness of from 50 to 500 Angstroms; a second layer having a thickness of from 100 to 1000 Angstroms made of bismuth formed on said first layer in a discontinuous island shape; and a ferromagnetic metal layer having a thickness of from 100 to 1000 Angstroms formed over said second layer, said medium having isotropic magnetic characteristics in the plane of the ferromagnetic metal layer.
Claim 4
Dependent Claim
90 words
A magnetic recording medium comprising: a non-magnetic substrate; a first layer formed continuously covering said substrate made of amorphous silicon and/or silicon compound having a thickness of from 50 to 500 Angstroms; a second layer having a thickness of from 100 to 1000 Angstroms made of bismuth formed on said first layer in a discontinuous island shape; and a ferromagnetic metal layer having a thickness of from 100 to 1000 Angstroms formed over said second layer, said medium having isotropic magnetic characteristics in the plane of the ferromagnetic metal layer.
Claim 5
Dependent Claim
80 words
A magnetic recording medium comprising: a non-magnetic substrate, a first layer composed of bismuth in a discontinuous island shape having a thickness between 10 Å and 1000 Å on said non-magnetic substrate, and a ferromagnetic layer having a thickness of from 100 to 1000 Angstroms formed over said first layer by vapor deposition of ferromagnetic metal in a direction normal to a surface of said substrate, said recording medium having isotropic magnetic characteristics in the plane of the ferromagnetic layer.
Claim 6
Dependent Claim
80 words
A magnetic recording medium comprising: a non-magnetic substrate, a first layer composed of bismuth in a discontinuous island shape having a thickness between 10 Å and 1000 Å on said non-magnetic substrate, and a ferromagnetic layer having a thickness of from 100 to 1000 Angstroms formed over said first layer by vapor deposition of ferromagnetic metal in a direction normal to a surface of said substrate, said recording medium having isotropic magnetic characteristics in the plane of the ferromagnetic layer.
Claim 7
Dependent Claim
22 words
A magnetic recording medium according to claim 2 and 3, wherein said ferromagnetic metal layer is formed of cobalt or cobalt alloy.
Claim 8
Dependent Claim
33 words
A magnetic recording medium according to claim 2 and 3, wherein said first layer and said ferromagnetic metal layer result from deposition of said layers at a substrate temperature higher than 130° C.
Claim 9
Dependent Claim
30 words
A magnetic recording medium according to claim 2, wherein said first layer is made of a material selected from Si, SiO 2 , Si 3 N 4 , and SiC.
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) | 1988-09-02 | 1989-03-04 | 1989-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-02 | 1993-03-04 | 1993-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-02 | 1997-03-04 | 1997-09-03 | $7700.00 | Window Closed / Lapsed |