Patent US4808489A successfully refreshed from Google Patents.
US4808489A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing magnetic disc
Assignee: Victor Company of Japan Ltd
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Filing: 1987-10-08
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Granted: 1989-02-28
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Expires: 2007-10-08
Abstract
Abstract A magnetic disc comprises a non-magnetic underlayer formed on a substantially flat surface of a substrate by growing grains of a magnetic material in a circumferential direction of the magnetic disc, and a magnetic layer formed on the non-magnetic underlayer, where the magnetic easy axis of the magnetic layer is oriented in the circumferential direction of the magnetic disc. A method of producing the magnetic disc forms the magnetic layer so that the magnetic easy axis thereof becomes oriented in the circumferential direction of the magnetic disc.
Inventors
- 👤 Toshiro Abe
- 👤 Toshikazu Nishihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 21:14
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; C; C23; C23C; C23C14/00; C23C14/04; C23C14/042; C23C14/06; C23C14/14; C23C14/16; C23C14/165; G11B5/85; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
82 words
A magnetic disc comprising: a disc-shaped substrate; a non-magnetic underlayer formed on a substantially flat surface of said substrate, said non-magnetic underlayer being made of a non-magnetic material and having grains thereof oriented in a circumferential direction of said substrate; and a magnetic layer formed on said non-magnetic underlayer, said magnetic layer being made of a magnetic material and having a magnetic easy axis thereof oriented in the circumferential direction of said substrate due to a grain orientation of said non-magnetic underlayer.
Claim 2
Dependent Claim
82 words
A magnetic disc comprising: a disc-shaped substrate; a non-magnetic underlayer formed on a substantially flat surface of said substrate, said non-magnetic underlayer being made of a non-magnetic material and having grains thereof oriented in a circumferential direction of said substrate; and a magnetic layer formed on said non-magnetic underlayer, said magnetic layer being made of a magnetic material and having a magnetic easy axis thereof oriented in the circumferential direction of said substrate due to a grain orientation of said non-magnetic underlayer.
Claim 3
Dependent Claim
25 words
A magnetic disc as claimed in claim 1, in which said non-magnetic underlayer is made of chromium and said magnetic layer is made of cobalt-nickel.
Claim 4
Dependent Claim
34 words
A magnetic disc as claimed in claim 1 in which said non-magnetic underlayer has a thickness of approximately 750Å to 5000Å and said magnetic layer has a thickness of approximately 400Å to 800 Å.
Claim 5
Dependent Claim
191 words
A magnetic disc having a disc-shaped substrate; a non-magnetic underlayer formed on a sustantially flat surface of said substrate, said non-magnetic underlayer being made of a non-magnetic material and having grains thereof oriented in a circumferential direction of said substrate; and a magnetic layer formed on said non-magnetic underlayer, said magnetic layer being made of a magnetic material and having a magnetic easy axis thereof oriented in the circumferential direction of said substrate due to a grain orientation of said non-magnetic underlayer, said magnetic disc being manufactured by a method comprising the steps of: forming a non-magnetic underlayer made of a non-magnetic material on a disc-shaped substrate by carrying out a physical vapor deposition by use of a mask having an opening with a predetermined diameter so that grains of the non-magnetic material grow and become oriented in a circumferential direction of said substrate, said mask being arranged substantially coaxially to said substrate, and forming a magnetic layer made of a magnetic material on said non-magnetic underlayer by carrying out a physical vapor deposition, said magnetic layer having a magnetic easy axis thereof oriented in the circumferential direction of said substrate.
Claim 6
Dependent Claim
191 words
A magnetic disc having a disc-shaped substrate; a non-magnetic underlayer formed on a sustantially flat surface of said substrate, said non-magnetic underlayer being made of a non-magnetic material and having grains thereof oriented in a circumferential direction of said substrate; and a magnetic layer formed on said non-magnetic underlayer, said magnetic layer being made of a magnetic material and having a magnetic easy axis thereof oriented in the circumferential direction of said substrate due to a grain orientation of said non-magnetic underlayer, said magnetic disc being manufactured by a method comprising the steps of: forming a non-magnetic underlayer made of a non-magnetic material on a disc-shaped substrate by carrying out a physical vapor deposition by use of a mask having an opening with a predetermined diameter so that grains of the non-magnetic material grow and become oriented in a circumferential direction of said substrate, said mask being arranged substantially coaxially to said substrate, and forming a magnetic layer made of a magnetic material on said non-magnetic underlayer by carrying out a physical vapor deposition, said magnetic layer having a magnetic easy axis thereof oriented in the circumferential direction 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) | 1992-02-28 | 1992-08-29 | 1993-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-28 | 1996-08-29 | 1997-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-28 | 2000-08-29 | 2001-02-28 | $7700.00 | Window Closed / Lapsed |