US4996622A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic disk with textured area on part of disk
Assignee: Nippon Sheet Glass Co Ltd
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Filing: 1989-12-18
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Granted: 1991-02-26
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Expires: 2009-12-18
Abstract
Abstract A magnetic disk in which a texture is formed in a first region spaced apart from an opening formed in a glass substrate by a predetermined distance, and a lubricant is coated on only the texture. The texture is not formed in a second region serving as a data surface, and an undercoating film, a magnetic recording film, and a protective film are sequentially coated on the surface of the glass substrate. In this magnetic disk, a floating amount of a magnetic head can be set to be small, and high-density data can be recorded. The data surface can be free from contamination by dust.
Inventors
- 👤 Nobuyuki Takatsuki
- 👤 Kyoichi Shukuri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:40
CPC Classifications
G; G11; G11B; G11B23/00; G11B23/50; G11B23/505; G11B23/507; G11B5/00; G11B5/74; G11B5/82
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
68 words
A magnetic disk comprising a glass substrate with an opening in a central portion, an undercoating film formed on said glass substrate, a magnetic recording film formed on said undercoating film, and a protective film formed on said magnetic recording film, wherein a texture is formed in a first region spaced apart from said opening by a predetermined distance, and a lubricant is coated on only said texture.
Claim 2
Dependent Claim
68 words
A magnetic disk comprising a glass substrate with an opening in a central portion, an undercoating film formed on said glass substrate, a magnetic recording film formed on said undercoating film, and a protective film formed on said magnetic recording film, wherein a texture is formed in a first region spaced apart from said opening by a predetermined distance, and a lubricant is coated on only said texture.
Claim 3
Dependent Claim
25 words
A magnetic disk according to claim 1, including a second region except for said first region, said second region not being provided with a texture.
Claim 4
Dependent Claim
28 words
A magnetic disk according to claim 1 or claim 2, a radial width of said first region is set within the range of 5 mm to 10 mm.
Claim 5
Dependent Claim
54 words
A magnetic disk according to claim 1 or claim 2, a roughness of a surface of said first region is given such that a central line average roughness Ra falls within the range of 2 nm to 20 nm, and a maximum height Rmax falls within the range of 20 nm to 200 nm.
Claim 6
Dependent Claim
37 words
A magnetic disk according to claim 1, wherein said undercoating film consists of at least one member selected from the group consisting of Cr and Ni--P, and is formed on the entire surface of said glass substrate.
Claim 7
Dependent Claim
38 words
A magnetic disk according to claim 1, wherein said magnetic recording film consists of at least one member selected from the group consisting of Co--Ni--Cr, Co--Ni, and Co--Ni--P, and is formed on the surface of said undercoating film.
Claim 8
Dependent Claim
40 words
A magnetic disk according to claim 1, wherein said protective film consists of at least one member selected from the group consisting of carbon and SiO 2 , and is formed on the entire surface of said magnetic recording film.
Claim 9
Dependent Claim
24 words
A magnetic disk according to claim 1, wherein said lubricant consists of fluorocarbon, and is coated on said protective film formed on said texture.
Claim 10
Dependent Claim
28 words
A magnetic disk according to claim 1, wherein a thickness of a coating layer of said lubricant is set within the range of 1 nm to 15 nm.
Claim 11
Dependent Claim
62 words
A magnetic disk according to claim 2, wherein a data surface is formed in said second region, and a roughness of a surface of said data surface is given such that a central line average roughness Ra falls within the range of 1 nm to 10 nm, and a maximum height Rmax falls within the range of 10 nm to 100 nm.
References Cited (Backward Citations)
US4152487A
Cited
US4738885A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-25 | 1994-08-27 | 1995-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-25 | 1998-08-27 | 1999-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-25 | 2002-08-27 | 2003-02-26 | $7700.00 | Window Closed / Lapsed |