US4544574A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing a magnetic recording medium
Assignee: Fujifilm Business Innovation Corp
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Filing: 1983-11-28
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Granted: 1985-10-01
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Expires: 2003-11-28
Abstract
Abstract A method for manufacturing a magnetic recording medium wherein a first magnetic layer having a repetitive magnetization pattern is formed on a base layer, an intermediate layer of non-magnetic material is formed over the first magnetic layer, and a second magnetic layer in which magnetic particles are orientated in a predetermined direction is formed on the intermediate layer.
Inventors
- 👤 Teruhiko Itami
- 👤 Toshifumi Kimoto
- 👤 Akira Yamasawa
- 👤 Koichi Saitoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 05:52
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
117 words
A method for manufacturing a magnetic recording medium comprising the steps of: forming a first magnetic layer on a non-magnetic base member; forming a second magnetic layer over said first magnetic layer, wherein the magnetic force and the residual magnetization of said first magnetic layer is greater than said second magnetic layer; drying said first and second magnetic layers; orienting the magnetic particles in said first magnetic layer and said second magnetic layer in a common direction; forming a repetitive magnetization pattern in said first magnetic layer and said second magnetic layer; and erasing said repetitive magnetization pattern in said second magnetic layer by orienting the magnetic particles in said second magnetic layer in a common direction.
Claim 2
Independent Claim
117 words
A method for manufacturing a magnetic recording medium comprising the steps of: forming a first magnetic layer on a non-magnetic base member; forming a second magnetic layer over said first magnetic layer, wherein the magnetic force and the residual magnetization of said first magnetic layer is greater than said second magnetic layer; drying said first and second magnetic layers; orienting the magnetic particles in said first magnetic layer and said second magnetic layer in a common direction; forming a repetitive magnetization pattern in said first magnetic layer and said second magnetic layer; and erasing said repetitive magnetization pattern in said second magnetic layer by orienting the magnetic particles in said second magnetic layer in a common direction.
Claim 3
Dependent Claim
23 words
A method according to claim 1 further including the step of forming a non-magnetic intermediate layer between said first and second magnetic layers.
Claim 4
Dependent Claim
48 words
A method according to claim 1 wherein said step of forming said periodically repetitive magnetization pattern in said first magnetic layer comprises the steps of: positioning a first magnetic write head beneath said base layer; and applying a periodically varying electrical signal to said first magnetic write head.
Claim 5
Dependent Claim
41 words
A method according to claim 1 wherein said magnetizing step comprises the steps of: positioning a second magnetic write head proximate the upper surface of said second magnetic layer; and applying a constant driving voltage to said second magnetic write head.
Claim 6
Dependent Claim
38 words
A method according to claim 2, wherein said step of forming said first magnetic layer comprises the step of applying a slurry of said magnetizable material to the upper surface of said base layer with a doctor blade.
Claim 7
Dependent Claim
38 words
A method according to claim 2, wherein said step of forming said intermediate layer comprises the step of applying a slurry of said non-magnetizable material to the upper surface of said first magnetic layer with a doctor blade.
Claim 8
Dependent Claim
37 words
A method according to claim 2, wherein said step of forming said second magnetic layer comprises the step of applying a slurry of magnetizable material to the upper surface of said intermediate layer with a doctor blade.
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) | 1988-09-30 | 1989-04-01 | 1989-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-30 | 1993-04-01 | 1993-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-30 | 1997-04-01 | 1997-10-01 | $7700.00 | Window Closed / Lapsed |