US4539264A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Sony Corp
•
Filing: 1983-10-06
•
Granted: 1985-09-03
•
Expires: 2003-10-06
Abstract
Abstract A magnetic recording medium having a non-magnetic substrate, a bismuth layer of less than 100 ANGSTROM thick formed on one major surface of the non-magnetic substrate and a magnetic metal thin film formed on the bismuth layer.
Inventors
- 👤 Kenji Yazawa
- 👤 Kenichi Baba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 04:39
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/66; G11B5/676; 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; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
68 words
A magnetic recording medium comprising: a non-magnetic substrate; a first layer made of bismuth formed on said substrate, said first layer having a thickness less than 100 Å; and a ferromagnetic metal layer of Co or Co-Ni alloy formed over said first layer without further physical treatment of said first layer, said magnetic recording medium having isotropic magnetic characteristics on a major surface of said magnetic recording medium.
Claim 2
Dependent Claim
68 words
A magnetic recording medium comprising: a non-magnetic substrate; a first layer made of bismuth formed on said substrate, said first layer having a thickness less than 100 Å; and a ferromagnetic metal layer of Co or Co-Ni alloy formed over said first layer without further physical treatment of said first layer, said magnetic recording medium having isotropic magnetic characteristics on a major surface of said magnetic recording medium.
Claim 3
Dependent Claim
22 words
A magnetic recording medium according to claim 1, wherein said ferromagnetic metal layer has a thickness ranging from 100 to 1000 Å.
Claim 4
Dependent Claim
17 words
A magnetic recording medium according to claim 1, wherein said ferromagnetic metal layer is made of cobalt.
Claim 5
Dependent Claim
26 words
A magnetic recording medium according to claim 1, wherein said ferromagnetic metal layer is made of Co-Ni alloy containing Ni of 20 to 50 atomic %.
Claim 6
Dependent Claim
23 words
A magnetic recording medium according to claim 1, wherein said ferromagnetic metal layer has a ferromagnetic metal compound layer formed on its surface.
Claim 7
Dependent Claim
23 words
A magnetic recording medium according to claim 1 further comprising a bismuth layer and a ferromagnetic layer superposed on said ferromagnetic metal layer.
Claim 8
Dependent Claim
21 words
A magnetic recording medium according to claim 1, wherein said bismuth layer and ferromagnetic layer are deposited successively by vacuum evaporation.
References Cited (Backward Citations)
US4307156A
Cited
JPS563142A
Cited
US4254189A
Cited
JPS5634139A
Cited
JPS5634150A
Cited
US4387136A
Cited
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 |