Patent US4741922A successfully refreshed from Google Patents.
US4741922A
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Method of manufacturing a magnetic storage media
Assignee: QED Intellectual Property Ltd
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Filing: 1986-06-23
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Granted: 1988-05-03
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Expires: 2006-06-23
Abstract
Abstract Transverse bowing of a plastics web coated with a magnetic thin metal film is substantially eliminated by laterally stretching the coated web such that the lateral stress applied to the metal film exceeds the tensile strength of the film and the lateral stress applied to the plastics web lies within the yield point of the plastics material. The coated web is stretched by passage over a curved roll adjusted to provide a lateral strain of at least 1% and typically 1.8% in the web, and such stretching may cause a pattern of interlaced micro-cracks to occur in the metal film. Recording tapes slit from such stretched webs exhibit negligible cupping, and the pressure of micro-cracks has no adverse effect on recording performance or wear.
Inventors
- 👤 James L. S. Wales
- 👤 Robert A. Woolley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:22
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
83 words
A method of manufacturing a magnetic storage medium including the steps of coating a web of flexible plastics material with a thin film of a magnetic metal or alloy and laterally stretching the coated web such that the lateral stress applied to the metal film exceeds the tensile strength of the film and the lateral stress applied to the plastics web lies within the yield point of the plastics material, whereby curvature of the medium caused by stress in the film is reduced.
Claim 2
Independent Claim
83 words
A method of manufacturing a magnetic storage medium including the steps of coating a web of flexible plastics material with a thin film of a magnetic metal or alloy and laterally stretching the coated web such that the lateral stress applied to the metal film exceeds the tensile strength of the film and the lateral stress applied to the plastics web lies within the yield point of the plastics material, whereby curvature of the medium caused by stress in the film is reduced.
Claim 3
Dependent Claim
21 words
A method according to claim 1 wherein the web is laterally stretched to have a lateral strain of at least 0.010.
Claim 4
Dependent Claim
13 words
A method according to claim 2 wherein the lateral strain is substantially 0.018.
Claim 5
Dependent Claim
68 words
A method according to claim 1 wherein the recording medium is laterally stretched by passage over a curved roll to controllably provide a lateral strain S in the web which is substantially defined by the expression ##EQU10## wherein the curved roll has a width L, a bow B as hereinbefore defined and a sectional diameter 2r, and the web has an angle of wrap α over the roll.
Claim 6
Independent Claim
27 words
A method according to claims 4 wherein L is substantially 190 mm, r is substantially 19 mm, α is substantially 90° and B is substantially 3 mm.
Claim 7
Dependent Claim
27 words
A method according to claim 3 wherein L is substantially 700 mm, r is substantially 60 mm, α is substantially 90° and B is substantially 13 mm.
Claim 8
Dependent Claim
16 words
A method according to claim 1 wherein said thin film is an evaporated cobalt nickel alloy.
Claim 9
Dependent Claim
16 words
A method according to claim 1 including the step of slitting the laterally stretched coated web.
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) | 1991-05-03 | 1991-11-02 | 1992-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-03 | 1995-11-02 | 1996-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-03 | 1999-11-02 | 2000-05-03 | $7700.00 | Window Closed / Lapsed |