US4409281A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1981-04-17
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Granted: 1983-10-11
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Expires: 2001-04-17
Abstract
Abstract A magnetic recording medium is described comprising a first layer comprising a magnetic iron oxide powder dispersed in a binder formed on a nonmagnetic support, a second layer formed on the first layer comprising a ferromagnetic metal powder dispersed in a binder, and having a greater coercive force than the first layer, and a third layer comprising a thin ferromagnetic metal film formed on the second layer in a thickness of from 0.01μ to 0.5μ.
Inventors
- 👤 Tatsuji Kitamoto
- 👤 Goro Akashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:31
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
102 words
A magnetic recording recording medium comprising a first layer comprised in a magnetic iron oxide powder dispersed in a binder formed on a non-magnetic support having a coercive force of from 200 to 700 oersteds, a second layer formed on the first layer comprising a ferromagnetic metal powder dispersed in a binder and having a greater coercive force than that of the first layer of from 600 to 1300 oersteds, and a third layer comprising a thin ferromagnetic metal film formed on the second layer in a thickness of from 0.01μ to 0.5μ and having a coercive force greater than 400 oersteds.
Claim 2
Dependent Claim
102 words
A magnetic recording recording medium comprising a first layer comprised in a magnetic iron oxide powder dispersed in a binder formed on a non-magnetic support having a coercive force of from 200 to 700 oersteds, a second layer formed on the first layer comprising a ferromagnetic metal powder dispersed in a binder and having a greater coercive force than that of the first layer of from 600 to 1300 oersteds, and a third layer comprising a thin ferromagnetic metal film formed on the second layer in a thickness of from 0.01μ to 0.5μ and having a coercive force greater than 400 oersteds.
Claim 3
Dependent Claim
17 words
A magnetic recording medium as in claim 1 wherein said third layer is formed by vapor deposition.
Claim 4
Dependent Claim
21 words
A magnetic recording medium as in claim 1 wherein said third layer is formed by plating, ion plating, or vapor deposition.
Claim 5
Dependent Claim
66 words
A magnetic recording medium as in claim 1, 2, or 3, wherein the third layer comprises a thin ferromagnetic metal film selected from group consisting of Co, Fe, Ni, Co-Ni, Co-Fe, Co-V, Co-Y, Co-Si, Co-Mn, Co-Fe-Ni, Co-R, wherein R is a rare-earth element, Co-B, Co-Ni-B, Co-Ni-Ag, Co-Ni-Re, Co-Mn-P, Co-Zn-P, Co-Pb-P, Co-Sm-Cu, Co-Ni-Fe-B, Fe-B, Fe-Ni, Fe-Rh, Fe-V, Co-P, Co-Ni-P, Co-Fe-P, Co-Ni-Fe-P, Co-Ni-Mn-P, Co-Ni-N, Co-N, Fe-N and Co-Fe-N.
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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) | 1986-10-10 | 1987-04-11 | 1987-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-10 | 1991-04-11 | 1991-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-10 | 1995-04-11 | 1995-10-11 | $7700.00 | Window Closed / Lapsed |