US4939614A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic disk medium with circumferentially textured surfaces and varied surface roughness and method of producing the same
Assignee: HGST Japan Ltd
•
Filing: 1988-03-31
•
Granted: 1990-07-03
•
Expires: 2008-03-31
Abstract
Abstract A magnetic disk medium in which texture working is performed on surfaces of a substrate or on surfaces of subbing films provided on the substrate to attain circumferential worked-traces so that the contact start stop area thereof is different from the recording/reproducing area thereof in roughness of the worked surfaces.
Inventors
- 👤 Takaaki Shirakura
- 👤 Shinya Matsuoka
- 👤 Hiroshi Yashiki
- 👤 Masanori Arayashiki
- 👤 Masaki Ohura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:20
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/73; G11B5/739; G11B5/73911; G11B5/73913; G11B5/73917; G11B5/73919; G11B5/74; G11B5/82; G11B5/84
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
47 words
A magnetic disk medium for use in a magnetic disk apparatus, comprising: a circumferentially textured substrate; magnetic films provided on said surfaces of said substrate; protective films provided on said magnetic films; said substrate having surface roughness which varies in the radial direction of said disk medium.
Claim 2
Dependent Claim
47 words
A magnetic disk medium for use in a magnetic disk apparatus, comprising: a circumferentially textured substrate; magnetic films provided on said surfaces of said substrate; protective films provided on said magnetic films; said substrate having surface roughness which varies in the radial direction of said disk medium.
Claim 3
Dependent Claim
37 words
A magnetic disk medium according to claim 1, in which said substrate includes a recording/reproducing area and a contact start stop area, said recording/reproducing area having plane accuracy higher than that of said contact start stop area.
Claim 4
Dependent Claim
49 words
A magnetic disk medium according to claim 2, in which average roughness in said recording/reproducing area is within a range of from 5 nm to 10 nm, and in which average roughness in said contact start stop area is within a range of from 50 nm to 70 nm.
Claim 5
Dependent Claim
20 words
A magnetic disk medium according to claim 1, in which said magnetic disk medium is a thin film disk medium.
Claim 6
Dependent Claim
16 words
A magnetic disk medium according to claim 1, in which said magnetic films have shape anisotropy.
Claim 7
Dependent Claim
66 words
A magnetic disk medium according to claim 1, wherein average roughness in a recording/reproducing area of said substrate, said protective films and said magnetic films is within a range of from 5 nm to 10 nm, and average roughness in a contact start stop area of said substrate, said protective films and said magnetic films is within a range of from 50 nm to 70 nm.
Claim 8
Dependent Claim
52 words
A magnetic disk medium for use in a magnetic disk apparatus, comprising: a substrate; circumferentially textured subbing films provided on said substrate; magnetic films provided on said subbing films; protective films provided on said magnetic films; said subbing films having surface roughness which varies in the radial direction of said disk medium.
Claim 9
Dependent Claim
52 words
A magnetic disk medium for use in a magnetic disk apparatus, comprising: a substrate; circumferentially textured subbing films provided on said substrate; magnetic films provided on said subbing films; protective films provided on said magnetic films; said subbing films having surface roughness which varies in the radial direction of said disk medium.
Claim 10
Dependent Claim
40 words
A magnetic disk medium according to claim 6, in which each of said subbing films includes a recording/reproducing area and a contact start stop area, said recording/reproducing area having plane accuracy higher than that of said contact start stop area.
Claim 11
Dependent Claim
49 words
A magnetic disk medium according to claim 8, in which average roughness in said recording/reproducing area is within a range of from 5 nm to 10 nm, and in which average roughness in said contact start stop area is within a range of from 50 nm to 70 nm.
Claim 12
Dependent Claim
20 words
A magnetic disk medium according to claim 7, in which said magnetic disk medium is a thin film disk medium.
Claim 13
Dependent Claim
16 words
A magnetic disk medium according to claim 7, in which said magnetic films have shape anisotropy.
Claim 14
Dependent Claim
68 words
A magnetic disk medium according to claim 7, wherein average roughness in a recording/reproducing area of said subbing films, said protective films and said magnetic films is within a range of from 5 nm to 10 nm and average roughness in a contact start stop area of said subbing films, and protective films and said magnetic films is within a range of from 50 nm to 70 nm.
Claim 15
Independent Claim
87 words
A method of producing a magnetic disk medium, comprising the steps of: forming worked traces in surfaces of a substrate in a circumferential direction of said disk; grinding surfaces of said substrate to attain average roughness within a predetermined first range; grinding a recording/reproducing area of each of said surfaces of said substrate to attain average roughness within a predetermined second range in a recording/reproducing area of said disk medium; forming magnetic films onto said surfaces of said substrate; and forming protective films onto said magnetic films.
Claim 16
Independent Claim
87 words
A method of producing a magnetic disk medium, comprising the steps of: forming worked traces in surfaces of a substrate in a circumferential direction of said disk; grinding surfaces of said substrate to attain average roughness within a predetermined first range; grinding a recording/reproducing area of each of said surfaces of said substrate to attain average roughness within a predetermined second range in a recording/reproducing area of said disk medium; forming magnetic films onto said surfaces of said substrate; and forming protective films onto said magnetic films.
Claim 17
Dependent Claim
29 words
A method of producing a magnetic disk medium according to claim 13, in which said average roughness within said first range is larger than that within said second range.
Claim 18
Dependent Claim
45 words
A method of producing a magnetic disk medium according to claim 14, in which said average roughness within said first range is from 50 nm to 70 nm, and in which said average roughness within said second range is from 5 nm to 10 nm.
Claim 19
Dependent Claim
24 words
A method of producing a magnetic disk medium according to claim 13, in which said magnetic disk medium is a thin film disk medium.
Claim 20
Dependent Claim
20 words
A method of producing a magnetic disk medium according to claim 13, in which said magnetic films have shape anisotropy.
Claim 21
Dependent Claim
66 words
A magnetic disk medium according to claim 13, wherein average roughness in a recording/reproducing area of said substrate, said protective films and said magnetic films is within a range of from 5 nm to 10 nm, and average roughness in a contact start stop area of said substrate, said protective films and said magnetic films is within a range of from 50 nm to 70 nm.
Claim 22
Independent Claim
90 words
A method of producing a magnetic disk medium, comprising the steps of: forming subbing films onto a substrate; forming worked traces in a surface of said subbing films in a circumferential direction of the disk; grinding surfaces of said subbing films to attain average roughness within a predetermined first range; grinding a recording/reproducing area of each of said surfaces of said subbing films to attain average roughness within a predetermined second range; forming magnetic films onto said surfaces of said subbing films; and forming protective films onto said magnetic films.
Claim 23
Independent Claim
90 words
A method of producing a magnetic disk medium, comprising the steps of: forming subbing films onto a substrate; forming worked traces in a surface of said subbing films in a circumferential direction of the disk; grinding surfaces of said subbing films to attain average roughness within a predetermined first range; grinding a recording/reproducing area of each of said surfaces of said subbing films to attain average roughness within a predetermined second range; forming magnetic films onto said surfaces of said subbing films; and forming protective films onto said magnetic films.
Claim 24
Dependent Claim
29 words
A method of producing a magnetic disk medium according to claim 19, in which said average roughness within said first range is larger than that within said second range.
Claim 25
Dependent Claim
45 words
A method of producing a magnetic disk medium according to claim 20, in which said average roughness within said first range is from 50 nm to 70 nm, and in which said average roughness within said second range is from 5 nm to 10 nm.
Claim 26
Dependent Claim
24 words
A method of producing a magnetic disk medium according to claim 19, in which said magnetic disk medium is a thin film disk medium.
Claim 27
Dependent Claim
20 words
A method of producing a magnetic disk medium according to claim 19, in which said magnetic films have shape anisotropy.
Claim 28
Dependent Claim
68 words
A magnetic disk medium according to claim 19, wherein average roughness in a recording/reproducing area of said subbing films, said protective films and said magnetic films is within a range of from 5 nm to 10 nm, and average roughness in a contact start stop area of said subbing films, said protective films and said magnetic films is within a range of from 50 nm to 70 nm.
References Cited (Backward Citations)
JPS5423508A
Cited
DE2948845A1
Cited
US4419701A
Cited
US4488189A
Cited
JPS613322A
Cited
JPS6040530A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-02 | 1994-01-01 | 1994-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-02 | 1998-01-01 | 1998-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-02 | 2002-01-01 | 2002-07-03 | $7700.00 | Window Closed / Lapsed |