US4803577A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vertical magnetic recording system using rigid disk
Assignee: TDK Corp
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Filing: 1986-06-09
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Granted: 1989-02-07
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Expires: 2006-06-09
Abstract
Abstract A vertical recording system using a rigid disk medium with high recording density has a substrate made of alumina silicate resin glass and a vertical magnetic anisotropic film located on said substrate. The anisotropic film has an easy axis of magnetization in the thickness direction of the film, and the hard axis of magnetization in the film plane. The maximum surface roughness R max of said disk is less than 50 Å, and a magnetic recording head which moves relative to the medium operates with said head contacted with the medium. A recording density higher than 200 KFRPI (kilo flux reversal per inch) is obtained by the present invention.
Inventors
- 👤 Joichiro Ezaki
- 👤 Kazumasa Fukuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:05
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/74; G11B5/82; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73921; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
82 words
A system for recording and reproducing information on a magnetic recording medium by using a magnetic head through relative movement between the head and the recording medium comprising a recording disk having a rigid disk substrate made of alumina silicate resin glass, and a vertical magnetic anisotropic film coupled with said substrate, the maximum surface roughness R max of said disk being less than 50 Å and the spacing between said head and said disk in operation being less than 0.1 micron.
Claim 2
Independent Claim
82 words
A system for recording and reproducing information on a magnetic recording medium by using a magnetic head through relative movement between the head and the recording medium comprising a recording disk having a rigid disk substrate made of alumina silicate resin glass, and a vertical magnetic anisotropic film coupled with said substrate, the maximum surface roughness R max of said disk being less than 50 Å and the spacing between said head and said disk in operation being less than 0.1 micron.
Claim 3
Dependent Claim
16 words
A system for recording and reproducing information according to claim 1, wherein said spacing is zero.
Claim 4
Dependent Claim
25 words
A system for recording and reproducing information according to claim 2, wherein contact pressure between said head and said medium is less than 10 gr.
References Cited (Backward Citations)
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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) | 1992-02-07 | 1992-08-08 | 1993-02-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-07 | 1996-08-08 | 1997-02-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-07 | 2000-08-08 | 2001-02-07 | $7700.00 | Window Closed / Lapsed |