Patent US4415942A successfully refreshed from Google Patents.
US4415942A
Expired / Lapsed
US
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Magnetic disk substrate of fiber-reinforced plastic
Assignee: International Business Machines Corp
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Filing: 1981-07-28
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Granted: 1983-11-15
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Expires: 2001-07-28
Abstract
Abstract The substrate 1 for magnetic disks takes the form of a laminate made up of a plurality of individual thin, fiber-reinforced, anisotropic and unidirectional lamellae. These lamellae are arranged staggered on top of each other at few angular spacings, i.e., at great angles of up to 60°, and are finally pressed together. The outer layers and lamellae, respectively, may be reinforced by stronger fibers or other material, such as carbon fibers outside and glass fibers inside, to influence the flexural modulus and the shearing modulus independently of each other. This makes for a substrate which consists of anisotropic material, whose characteristics are essentially isotropic, which is lighter than previously used substrates, and which has a higher critical number of revolutions.
Inventors
- 👤 Albert Frosch
- 👤 Holger Hinkel
- 👤 Georg Kraus
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:25
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73913; G11B5/74; G11B5/82
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
48 words
A magnetic disk substrate of plastic containing fibers, characterized in that said substrate is pressed in the form of a laminate from a plurality of thin lamellae of fiber-reinforced plastic, said lamellae being arranged on top of each other at equal angular spacings, θ=π/n, n, an integer, ≧3.
Claim 2
Dependent Claim
48 words
A magnetic disk substrate of plastic containing fibers, characterized in that said substrate is pressed in the form of a laminate from a plurality of thin lamellae of fiber-reinforced plastic, said lamellae being arranged on top of each other at equal angular spacings, θ=π/n, n, an integer, ≧3.
Claim 3
Dependent Claim
35 words
A magnetic disk substrate in accordance with claim 1, characterized in that said fibers in the individual lamellae in one direction are aligned to each other essentially in parallel so that said lamellae are anisotropic.
Claim 4
Dependent Claim
29 words
A magnetic disk substrate in accordance with claim 1, characterized in that the individual lamellae are arranged on top of each other at an angle of 0° and ±60°.
Claim 5
Dependent Claim
38 words
A magnetic disk substrate in accordance with claim 1, characterized in that the laminate structure extends respectively symmetrically to the center plane of said substrate and comprises an identical number of lamellae above and below said center plane.
Claim 6
Dependent Claim
62 words
A magnetic disk substrate in accordance with claim 4, characterized in that with each lamella arranged at a particular angle of arrangement on one side of said center plane of said substrate, there is associated one lamella with the same angle of arrangement on the other side of said center plane of said substrate, and all angular directions are provided equally frequently.
Claim 7
Dependent Claim
22 words
A magnetic disk substrate in accordance with claim 5, characterized in that said substrate is made up of up to 72 lamellae.
Claim 8
Dependent Claim
26 words
A magnetic disk substrate in accordance with claim 1, characterized in that the density of the outer lamellae is lower than that of the inner lamellae.
Claim 9
Dependent Claim
34 words
A magnetic disk substrate in accordance with claim 1, characterized in that the Young's modulus and the Poisson's ratio of the outer lamellae are greater than or equal to those of the inner lamellae.
Claim 10
Dependent Claim
30 words
A magnetic disk substrate in accordance with claim 8, characterized in that the Young's modulus of the fibers in the outer lamellae is greater than that in the inner lamellae.
Claim 11
Dependent Claim
25 words
A magnetic disk substrate in accordance with claim 9, characterized in that the outer lamellae contain carbon fibers and the inner lamellae contain glass fibers.
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) | 1986-11-14 | 1987-05-16 | 1987-11-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-11-14 | 1991-05-16 | 1991-11-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-11-14 | 1995-05-16 | 1995-11-15 | $7700.00 | Window Closed / Lapsed |