US4652483A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1984-03-14
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Granted: 1987-03-24
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Expires: 2004-03-14
Abstract
Abstract A magnetic recording medium comprises a non-magnetic substrate, a thin ferromagnetic film layer overlaid on the substrate, and a polymer film formed by plasma polymerization. The thin ferromagnetic film layer is composed of ferromagnetic columnar grains. The polymer film is overlaid on the thin ferromagnetic film layer so as to permeate into the spaces between the ferromagnetic columnar grains, thereby improving the corrosion resistance and durability of the magnetic recording medium.
Inventors
- 👤 Yoshihiro Arai
- 👤 Akira Nahara
- 👤 Kiyotaka Fukino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:04
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/722; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
64 words
A magnetic recording medium comprising a non-magnetic substrate, a thin ferromagnetic film layer composed of ferromagnetic columnar grains, and a polymer film formed by plasma polymerization, said polymer film being overlayed on said thin ferromagnetic film layer so as to permeate into the spaces between said ferromagnetic columnar grains, wherein said polymer film formed by plasma polymerization is prepared by polymerizing plasma of methane.
Claim 2
Dependent Claim
64 words
A magnetic recording medium comprising a non-magnetic substrate, a thin ferromagnetic film layer composed of ferromagnetic columnar grains, and a polymer film formed by plasma polymerization, said polymer film being overlayed on said thin ferromagnetic film layer so as to permeate into the spaces between said ferromagnetic columnar grains, wherein said polymer film formed by plasma polymerization is prepared by polymerizing plasma of methane.
Claim 3
Dependent Claim
26 words
A magnetic recording medium as defined in claim 1 wherein said non-magnetic substrate is a flexible plastic film exhibiting surface roughness of 0.012 μm or less.
Claim 4
Dependent Claim
36 words
A magnetic recording medium as defined in claim 1 wherein said thin ferromagnetic film layer is composed of a material selected from the group consisting of cobalt, a cobalt alloy, and a cobalt alloy containing oxygen.
Claim 5
Dependent Claim
22 words
A magnetic recording medium as defined in claim 1 wherein said thin ferromagnetic film layer has an obliquely deposited columnar grain structure.
Claim 6
Dependent Claim
22 words
A magnetic recording medium as defined in claim 1 wherein said thin ferromagnetic film layer has a thickness of about 1,400 Å.
Claim 7
Dependent Claim
29 words
A magnetic recording medium as defined in claim 1 wherein said polymer film formed by plasma polymerization has a thickness within the range of 20 Å to 800 Å.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-03-23 | 1990-09-22 | 1991-03-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-23 | 1994-09-22 | 1995-03-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-23 | 1998-09-22 | 1999-03-24 | $7700.00 | Window Closed / Lapsed |