US4578729A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Panasonic Holdings Corp
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Filing: 1982-10-15
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Granted: 1986-03-25
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Expires: 2002-10-15
Abstract
Abstract A magentic recording medium in which a thin ferromagnetic film is formed over a strip or sheet of plastic film whose surface is formed with grain-, rumple- or worm-like nodules into which may be dispersed finely divided particles of the diameter ranging from 0.01 to 0.2 mu m. In the case of a thin ferromagnetic metal film type recording medium, steep protrusions of the height ranging from 100 to 2,000 ANGSTROM are distributed over the surface at the average density of 104 to 106 per mm2.
Inventors
- 👤 Takashi Suzuki
- 👤 Hiroshi Fujimori
- 👤 Masaru Odagiri
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:25
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; G11B5/73935; G11B5/84; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24479; Y10T428/24612; Y10T428/25
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
66 words
A magnetic recording medium comprising a thin ferromagnetic metal film formed as a magnetic layer; and strip protrusions having a height between 100 and 2,000 A distributed over the surface of said magnetic layer at an average density ranging from 10 4 to 10 6 protrusions per mm 2 , and the ratio between the length and the height of said protrusions is less than 10:1.
Claim 2
Dependent Claim
66 words
A magnetic recording medium comprising a thin ferromagnetic metal film formed as a magnetic layer; and strip protrusions having a height between 100 and 2,000 A distributed over the surface of said magnetic layer at an average density ranging from 10 4 to 10 6 protrusions per mm 2 , and the ratio between the length and the height of said protrusions is less than 10:1.
Claim 3
Dependent Claim
17 words
A magnetic recording medium as set forth in claim 1, wherein said ratio is less than 5:1.
Claim 4
Dependent Claim
51 words
A recording medium as set forth in claim 1, wherein said surface of said magnetic layer is formed with gently sloping grain-rumple- or worm-like nodules having a height less than that of said protrusions and which are spaced apart from each other by a distance ranging between 0.1 and 10 μm.
Claim 5
Dependent Claim
27 words
A magnetic recording medium as set forth in claim 3, wherein said protrusions have a height at least 50 A higher than the height of said nodules.
References Cited (Backward Citations)
US4153920A
Cited
JPS53116115A
Cited
JPS53128683A
Cited
JPS5443703A
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JPS5494574A
Cited
US4233352A
Cited
JPS5610455A
Cited
JPS5616937A
Cited
JPS56101650A
Cited
US4420531A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-03-24 | 1989-09-23 | 1990-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-24 | 1993-09-23 | 1994-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-24 | 1997-09-23 | 1998-03-25 | $7700.00 | Window Closed / Lapsed |