US4208447A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for disorienting magnetic particles
Assignee: International Business Machines Corp
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Filing: 1978-06-05
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Granted: 1980-06-17
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Expires: 1998-06-05
Abstract
Abstract This invention provides an improved method and apparatus for manufacturing magnetic recording media; specifically, that which is to be used in the manufacture of flexible, magnetic recording disks. The process provides a sequence of disorienting magnetic fields in different directions and of diminishing strengths to form a magnetic media in which the magnetic particles are essentially disoriented and the media is, thereby, devoid of modulated signal envelopes.
Inventors
- 👤 Geoffrey Bate
- 👤 Larry P. Dunn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:58
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/842; G11B5/845
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
67 words
A method for manufacturing magnetic media comprising the steps of: coating a substrate material with ferromagnetic particles in a solution to create an uncured magnetic medium; applying to said uncured magnetic medium, a disorienting magnetic field of diminishing strength in alternate directions and reversing orientation to cause a random distribution of the particles; and drying said magnetic media, whereby a resultant disoriented particle magnetic medium is obtained.
Claim 2
Independent Claim
67 words
A method for manufacturing magnetic media comprising the steps of: coating a substrate material with ferromagnetic particles in a solution to create an uncured magnetic medium; applying to said uncured magnetic medium, a disorienting magnetic field of diminishing strength in alternate directions and reversing orientation to cause a random distribution of the particles; and drying said magnetic media, whereby a resultant disoriented particle magnetic medium is obtained.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein the substrate material is a web of polyethylene terephthalate.
Claim 4
Dependent Claim
18 words
The method of claim 1 wherein the directions for applying the magnetic fields alternate at angles of ±45°.
Claim 5
Dependent Claim
17 words
The method of claim 3 wherein the directional sequence of diminishing fields alternates at least ten times.
References Cited (Backward Citations)
US3627580A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-06-17 | 1983-12-17 | 1984-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-06-17 | 1987-12-17 | 1988-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-06-17 | 1991-12-17 | 1992-06-17 | $7700.00 | Window Closed / Lapsed |