US5080948A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording/reproducing system comprising a glass substrate thin film magnetic disk and a flying magnetic head with defined spacing and surface roughness
Assignee: TDK Corp
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Filing: 1989-05-19
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Granted: 1992-01-14
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Expires: 2009-05-19
Abstract
Abstract A magnetic recording medium comprising a glass substrate and a magnetic thin film thereon is provided for use in a magnetic recording/reproducing system having a flying magnetic head. Floating performance is improved when the glass substrate has a surface roughness Rmax of 10-80 A and the magnetic thin film has a surface roughness Rmax of 50-150 Å. Recording and reproducing information on a magnetic disk is carried out by driving the magnetic disk while keeping a magnetic head floating relative to the disk at a spacing therebetween of up to 0.2 μm.
Inventors
- 👤 Haruyuki Morita
- 👤 Joichiro Ezaki
- 👤 Yasufumi Uno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:48
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73921; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
129 words
A system for recording and reproducing information on a magnetic disk, comprising the magnetic disk and a magnetic head wherein the magnetic head floats on the disk during recording and reproducing operation, characterized in that said magnetic disk comprises a glass substrate and a magnetic thin film formed on at least one major surface thereof, the glass substrate on the major surface has a surface roughness Rmax in the range of 10 to 80 Å, the medium on the surface has a surface roughness Rmax in the range of 50 to 150 Å, and the sapcing between the disk and the flying head in operation is up to 0.2 μm; wherein the magnetic head on he air bearing surface has a surface roughness Rmax of up to 200 Å.
Claim 2
Independent Claim
129 words
A system for recording and reproducing information on a magnetic disk, comprising the magnetic disk and a magnetic head wherein the magnetic head floats on the disk during recording and reproducing operation, characterized in that said magnetic disk comprises a glass substrate and a magnetic thin film formed on at least one major surface thereof, the glass substrate on the major surface has a surface roughness Rmax in the range of 10 to 80 Å, the medium on the surface has a surface roughness Rmax in the range of 50 to 150 Å, and the sapcing between the disk and the flying head in operation is up to 0.2 μm; wherein the magnetic head on he air bearing surface has a surface roughness Rmax of up to 200 Å.
Claim 3
Dependent Claim
38 words
The system of claim 1 wherein the glass substrate has a surface roughness Rmax in the range of 30 to 80 Å and the medium has a surface roughness Rmax in the range of 80 to 150 Å.
Claim 4
Dependent Claim
16 words
The system of claim 1 wherein said glass substrate is at least a surface tempered glass.
Claim 5
Dependent Claim
14 words
The system of claim 1 wherein said magnetic thin film predominantly comprises iron oxide.
Claim 6
Dependent Claim
13 words
The system of claim 1 wherein said spacing is up to 0.1 μm.
Claim 7
Dependent Claim
42 words
The system of claim 1 wherein said magnetic head comprises a base and spaced magnetic poles of thin film structure on the base, said base and said poles defining an air bearing surface at one end adapted to face the magnetic disk.
Claim 8
Dependent Claim
18 words
The system of claim 1 wherein said magnetic head base has a Vickers hardness of at least 1000.
Claim 9
Dependent Claim
100 words
The system of claim 1 wherein the magnetic recording medium is produced by a process comprising the steps of: providing a glass substrate having on at least one major surface thereof a surface roughness Rmax in the range of 10 to 80 Å, forming a magnetic thin film on the at least one major surface of said glass substrate to provide a film-bearing substrate, and heating the film-bearing substrate at a temperature of 200 to 500 degrees C. for surface roughness adjustment to provide a surface roughness Rmax of the recording medium in the range of 50 to 150 Å.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-01-13 | 1995-07-15 | 1996-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-01-13 | 1999-07-15 | 2000-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-01-13 | 2003-07-15 | 2004-01-14 | $7700.00 | Window Closed / Lapsed |