US5314745A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium having a glass substrate, heat retaining non magnetic metal layer formed over the substrate, amorphous nip layer, Cr layer and magnetic layer
Assignee: United Module Corp
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Filing: 1992-08-18
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Granted: 1994-05-24
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Expires: 2012-08-18
Abstract
Abstract A magnetic recording medium comprising a substrate, a ground layer formed over at least one surface of the substrate, and a magnetic layer formed over the ground layer, the ground layer being formed of a material containing at least 95% by weight of Cr. The substrate comprises a base of glass plate, a nonmagnetic metal layer formed over at least one surface of the base, and an amorphous NiP layer formed over the nonmagnetic metal layer. The nonmagnetic metal layer is formed of a material containing at least 95% by weight of Cr, or a material containing at least 95% by weight of Ti or a material containing at least 95% by weight of Cr-Ti alloy. The recording medium has excellent flatness and a high coercive force.
Inventors
- 👤 Yoshinobu Okumura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 16:57
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/65; G11B5/656; G11B5/73; G11B5/7368; G11B5/7373; G11B5/739; G11B5/73911; G11B5/73913; G11B5/73921; G11B5/84; G11B5/8404; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12847; Y10T428/12854; Y10T428/12861; Y10T428/12944; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
100 words
A magnetic recording medium comprising a substrate, a ground layer made of a material containing at least 95% by weight of Cr and formed over one surface of the substrate, and a magnetic layer formed over the ground layer; said substrate comprising: a base of glass plate; a nonmagnetic metal layer formed over the glass base and having a thickness sufficient for retention of heat wherein the substrate is heated by infrared electromagnetic waves for forming the ground layer; and an amorphous NiP layer formed over the nonmagnetic metal layer and having a thickness of about 250 to 1000 angstroms.
Claim 2
Dependent Claim
100 words
A magnetic recording medium comprising a substrate, a ground layer made of a material containing at least 95% by weight of Cr and formed over one surface of the substrate, and a magnetic layer formed over the ground layer; said substrate comprising: a base of glass plate; a nonmagnetic metal layer formed over the glass base and having a thickness sufficient for retention of heat wherein the substrate is heated by infrared electromagnetic waves for forming the ground layer; and an amorphous NiP layer formed over the nonmagnetic metal layer and having a thickness of about 250 to 1000 angstroms.
Claim 3
Dependent Claim
61 words
A magnetic recording medium as defined in claim 1 wherein the ground layer is formed over each of opposite surfaces of the substrate, the magnetic layer being formed over the ground layer, and the non-magnetic metal layer is formed over ech of opposite surfaces of the base of the substrate, the amorphous NiP layer being formed over the nonmangetic metal layer.
Claim 4
Dependent Claim
22 words
A magnetic recording medium as defined in claim 1 wherein the nonmagnetic metal layer is at least about 300 angstroms in thickness.
Claim 5
Dependent Claim
19 words
A magnetic recording medium as defined in claim 1 wherein a protective layer is formed over the magnetic layer.
Claim 6
Dependent Claim
18 words
A magnetic recording medium as defined in claim 4 wherein the protective layer is coated with a lubricant.
Claim 7
Dependent Claim
62 words
A magnetic recording medium as defined in claim 1, wherein said nonmagnetic metal layer is made of a material selected from the group consisting of a material containing at least 95% by weight of Cr, a material containing at least 95% by weight of Ti or a material containing Cr and Ti having a combined amount of at least 95% by weight.
References Cited (Backward Citations)
US4794047A
Cited
JPH0229923A
Cited
JPH02246017A
Cited
US4990362A
Cited
US5037515A
Cited
US5084152A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-05-23 | 1997-11-22 | 1998-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-23 | 2001-11-22 | 2002-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-23 | 2005-11-22 | 2006-05-24 | $7700.00 | Window Closed / Lapsed |