Patent US4956220A successfully refreshed from Google Patents.
US4956220A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Maxell Ltd
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Filing: 1987-03-20
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Granted: 1990-09-11
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Expires: 2007-03-20
Abstract
Abstract A magnetic recording medium with improved output characteristics and durability is provided by using magnetic powder comprising iron-containing particles each of which carries a compound containing aluminum and/or a compound containing silicon in such amounts that, in the whole magnetic powder, a weight ratio of silicon to iron is from 0.010:1 to 0.150:1, a weight ratio of aluminum to iron is from 0.040:1 to 0.150:1, and a weight ratio of aluminum to silicon is from 1:1 to 15:1.
Inventors
- 👤 Toshinobu Sueyoshi
- 👤 Seiichi Asada
- 👤 Masahiro Amemiya
- 👤 Seigi Kawarai
- 👤 Akira Miyake
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 15:42
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/70615; G11B5/712; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/29; Y10T428/2982; Y10T428/2991; Y10T428/2993
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
88 words
A magnetic recording medium comprising a substrate and a magnetic layer formed on said substrate, said magnetic layer including iron-containing magnetic powder dispersed in a binder, said powder comprising particles the surfaces of which are covered with both a compound containing aluminum and a compound containing silicon in such amounts that a weight ratio of silicon to iron is from 0.010:1 to 0.090:1, a weight ratio of aluminum to iron is from 0.060:1 to 0.130:1 and a weight ratio of aluminum to silicon is from 2:1 to 15:1.
Claim 2
Dependent Claim
88 words
A magnetic recording medium comprising a substrate and a magnetic layer formed on said substrate, said magnetic layer including iron-containing magnetic powder dispersed in a binder, said powder comprising particles the surfaces of which are covered with both a compound containing aluminum and a compound containing silicon in such amounts that a weight ratio of silicon to iron is from 0.010:1 to 0.090:1, a weight ratio of aluminum to iron is from 0.060:1 to 0.130:1 and a weight ratio of aluminum to silicon is from 2:1 to 15:1.
Claim 3
Dependent Claim
28 words
The magnetic recording medium according to claim 1, wherein the magnetic powder is contained in the magnetic layer in a volume of not less than 15% by volume.
Claim 4
Dependent Claim
20 words
The magnetic recording medium according to claim 1, wherein the magnetic powder consists of particles having an easily oriented shape.
Claim 5
Dependent Claim
18 words
The magnetic recording medium according to claim 1, wherein the magnetic powder is a metal iron magnetic powder.
Claim 6
Dependent Claim
26 words
The magnetic recording medium according to claim 1, wherein said recording medium has a surface roughness of 0.01 μm in terms of center line average height.
Claim 7
Dependent Claim
22 words
The magnetic recording medium according to claim 1, wherein aluminum is present in the form of aluminum oxide or water-containing aluminum oxide.
Claim 8
Dependent Claim
38 words
The magnetic recording medium according to claim 1, wherein the magnetic powder consists of magnetic powder particles each having an under coating of a silicon-containing compound and an upper coating of a aluminum-containing compound on said under coating.
Claim 9
Dependent Claim
32 words
The magnetic recording medium according to claim 7, wherein the under coating consists of silicon oxide or water-containing silicon oxide, and the upper coating consists of aluminum oxide or water-containing aluminum oxide.
References Cited (Backward Citations)
US4255492A
Cited
US3814598A
Cited
US3736181A
Cited
US4043846A
Cited
US4169802A
Cited
US4400432A
Cited
US4404254A
Cited
US4336310A
Cited
US4390361A
Cited
JPS6422604A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-10 | 1994-03-12 | 1994-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-10 | 1998-03-12 | 1998-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-10 | 2002-03-12 | 2002-09-11 | $7700.00 | Window Closed / Lapsed |