US4606971A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Toshiba Corp
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Filing: 1984-08-10
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Granted: 1986-08-19
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Expires: 2004-08-10
Abstract
Abstract Disclosed is a magnetic recording medium comprised of a substrate and a layer of magnetic powder coated on a surface of the substrate, characterized in that the magnetic powder is hexagonal crystals having single domain crystalline magnetic anisotropy, particle sizes of 0.01 to 0.3 μm, particle size/thickness ratios of 2.3 to 15 and the tapping packing rate of said magnetic powder is 15% or more.
Inventors
- 👤 Tadashi Ido
- 👤 Osamu Kubo
- 👤 Masahiro Fukasawa
- 👤 Tatsumi Maeda
- 👤 Tutomu Nomura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:24
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/714; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
64 words
A magnetic recording medium comprised of a substrate and a layer of magnetic powder coated on a surface of said substrate, wherein said magnetic powder comprises hexagonal crystals having (a) single domain crystalline magnetic anisotropy, (b) particle sizes of 0.01 to 0.3 μm, and (c) particle size/thickness ratios of 2.3 to 15, the tapping packing rate of said magnetic powder being 15% or more.
Claim 2
Dependent Claim
64 words
A magnetic recording medium comprised of a substrate and a layer of magnetic powder coated on a surface of said substrate, wherein said magnetic powder comprises hexagonal crystals having (a) single domain crystalline magnetic anisotropy, (b) particle sizes of 0.01 to 0.3 μm, and (c) particle size/thickness ratios of 2.3 to 15, the tapping packing rate of said magnetic powder being 15% or more.
Claim 3
Dependent Claim
21 words
The magnetic recording medium according to claim 1, wherein the magnetic powder has a coersive force of 200 to 2000 oersteds.
Claim 4
Dependent Claim
21 words
The magnetic recording medium according to claim 1, wherein the magnetic powder is hexagonal ferrite powder or substituted hexagonal ferrite powder.
Claim 5
Dependent Claim
21 words
The magnetic recording medium according to claim 2, wherein the magnetic powder is hexagonal ferrite powder or substituted hexagonal ferrite powder.
Claim 6
Dependent Claim
60 words
The magnetic recording medium according to claim 2, wherein the magnetic powder is comprised of at least one selected from the group consisting of Fe- and Ni-containing Co alloys; Mn-Bi alloys; Mn-Al alloys; and alloys represented by the formulas RCo 5 and R 2 Co 17 , wherein R denotes a rare earth element and Co denotes a cobalt atom.
Claim 7
Dependent Claim
50 words
The magnetic recording medium according to claim 3, wherein the substituted hexagonal ferrite powder comprises powdery hexagonal ferrite the iron of which has been partly substituted with at least one element selected from the group consisting of cobalt, titanium, nickel, manganese, copper, zinc, indium, gallium, niobium, zirconim, vanadium and aluminum.
Claim 8
Dependent Claim
21 words
The magnetic recording medium according to claim 1, wherein the particle size of the hexagonal crystals is 0.03 to 0.2 μm.
Claim 9
Dependent Claim
17 words
The magnetic recording medium according to claim 1, wherein the particle size/thickness ratio is 2.8 to 5.
References Cited (Backward Citations)
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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) | 1989-08-18 | 1990-02-17 | 1990-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-18 | 1994-02-17 | 1994-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-18 | 1998-02-17 | 1998-08-19 | $7700.00 | Window Closed / Lapsed |