Patent US4725470A successfully refreshed from Google Patents.
US4725470A
Expired / Lapsed
US
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Magnetic disk medium
Assignee: Alps Alpine Co Ltd
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Filing: 1986-09-24
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Granted: 1988-02-16
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Expires: 2006-09-24
Abstract
Abstract A magnetic disk medium having a magnetic layer formed on its substrate, is characterized in that in a portion of the substrate where a magnetic head runs is formed a concave groove in which a cushion material is provided, whereby the contact pressure appearing between it and the magnetic head is lowered. Preferably, the cushion material is either plastic foam selected from the group consisting of polyurethane foam, polystyrene foam, cellular polyethylene, cellular rubber, cellular polyvinyl chloride, and foamed polyester, or elastic silicone resin.
Inventors
- 👤 Toshiyuki Katsuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 18:22
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/74; G11B5/82; G11B5/825; G11B5/62; G11B5/73; G11B5/739; G11B5/73911; G11B5/73921; G11B5/73923; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24479; Y10T428/24521; Y10T428/24537; Y10T428/249921; Y10T428/249953; Y10T428/249955; Y10T428/249958
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
80 words
A magnetic disk medium, for use in rotation relative to a magnetic head, having a magnetic layer formed on a surface of a substrate, characterized in that a groove concentric with the disk medium is formed in the surface of the substrate in the area over which the magnetic head runs, and a cushion material is provided in said groove so as to be flush with the disk substrate surface, and the magnetic layer is bonded onto the cushion material.
Claim 2
Dependent Claim
80 words
A magnetic disk medium, for use in rotation relative to a magnetic head, having a magnetic layer formed on a surface of a substrate, characterized in that a groove concentric with the disk medium is formed in the surface of the substrate in the area over which the magnetic head runs, and a cushion material is provided in said groove so as to be flush with the disk substrate surface, and the magnetic layer is bonded onto the cushion material.
Claim 3
Dependent Claim
36 words
A magnetic disk medium according to claim 1, wherein said cushion material is selected from the group consisting of polyurethane foam, polystyrene foam, cellular polyethylene, cellular rubber, cellular polyvinyl chloride, foamed polyester, and elastic silicone resin.
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) | 1991-02-15 | 1991-08-17 | 1992-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-15 | 1995-08-17 | 1996-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-15 | 1999-08-17 | 2000-02-16 | $7700.00 | Window Closed / Lapsed |