US4444835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Maxell Ltd
•
Filing: 1982-09-23
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Granted: 1984-04-24
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Expires: 2002-09-23
Abstract
Abstract A magnetic recording medium suitable for high-density recording, which comprises a magnetic layer containing uniaxial anisotropic, acicular iron oxide particles having a particle size of not more than 0.3 mu , with a surface layer containing a major amount of cobalt being formed on seeds of the magnetic particles, said magnetic recording medium having a residual magnetic flux density both in a vertical direction and in a horizontal or longitudinal direction of not less than 1000 gauss.
Inventors
- 👤 Fumio Togawa
- 👤 Shigeo Aoyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:04
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/842; G11B5/845; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70652; G11B5/70668; G11B5/70673; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
78 words
A magnetic recording medium which comprises a magnetic layer containing uniaxial anisotropic, acicular magnetic iron oxide particles having a particle size of not more than 0.3μ, said particles having a surface layer containing a major amount of cobalt formed thereon, said particles being oriented both in a vertical and a horizontal direction such that the residual magnetic flux of said magnetic recording medium is not less than 1000 gauss in both said vertical direction and said horizontal direction.
Claim 2
Dependent Claim
78 words
A magnetic recording medium which comprises a magnetic layer containing uniaxial anisotropic, acicular magnetic iron oxide particles having a particle size of not more than 0.3μ, said particles having a surface layer containing a major amount of cobalt formed thereon, said particles being oriented both in a vertical and a horizontal direction such that the residual magnetic flux of said magnetic recording medium is not less than 1000 gauss in both said vertical direction and said horizontal direction.
Claim 3
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said magnetic iron oxide particles have a cobalt content of 2 to 15% by weight.
References Cited (Backward Citations)
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US4237506A
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US4303699A
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US4337288A
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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) | 1987-04-24 | 1987-10-24 | 1988-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-04-24 | 1991-10-24 | 1992-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-04-24 | 1995-10-24 | 1996-04-24 | $7700.00 | Window Closed / Lapsed |