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US4480004A
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Magnetic recording medium
Assignee: Maxell Ltd
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Filing: 1982-09-23
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Granted: 1984-10-30
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Expires: 2002-09-23
Abstract
Abstract A magnetic recording medium suitable for high-density recording which comprises a substrate and a magnetic layer thereon, the magnetic layer containing acicular magnetic metal particles having a particle size of not more than 0.3μ and a squareness ratio in the vertical direction of the layer being not less than 0.4.
Inventors
- 👤 Fumio Togawa
- 👤 Takato Karashima
- 👤 Hiroshi Zaitsu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:38
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/714; G11B5/84; G11B5/842; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
74 words
A magnetic recording medium which comprises a substrate and a magnetic layer thereon, said magnetic layer containing acicular magnetic metal particles having a particle size of not more than 0.3μ, a squareness ratio in the vertical direction of said layer of not less than 0.4, a squareness ratio in the lengthwise direction of said layer being not less than 0.57 and a coercive force (Hc) in the lengthwise direction of 800 to 2,000 oersteds.
Claim 2
Dependent Claim
74 words
A magnetic recording medium which comprises a substrate and a magnetic layer thereon, said magnetic layer containing acicular magnetic metal particles having a particle size of not more than 0.3μ, a squareness ratio in the vertical direction of said layer of not less than 0.4, a squareness ratio in the lengthwise direction of said layer being not less than 0.57 and a coercive force (Hc) in the lengthwise direction of 800 to 2,000 oersteds.
Claim 3
Dependent Claim
22 words
A magnetic recording medium according to claim 1, wherein said magnetic particles have an acicular axial ratio of not more than 10.
Claim 4
Dependent Claim
26 words
A magnetic recording medium according to claim 1, wherein said magnetic particles have a coercive force (Hc) in the lengthwise direction of 1,200 to 2,000 oersteds.
Claim 5
Dependent Claim
23 words
A magnetic recording medium according to claim 1, wherein said magnetic particles have a maximum magnetization (σs) of not less than 100 emu/g.
Claim 6
Dependent Claim
27 words
A magnetic recording medium according to claim 3, wherein said magnetic particles have a coercive force (Hc) in the vertical direction of not less than 1,250 oersteds.
Claim 7
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said magnetic particles have a coercive force (Hc) in the lengthwise direction of 1,200 oersteds.
Claim 8
Dependent Claim
24 words
A magnetic recording medium according to claim 6, wherein said magnetic particles have a coercive force (Hc) in the vertical direction of 1,290 oersteds.
Claim 9
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said magnetic particles have a coercive force (Hc) in the lengthwise direction of 1360 oersteds.
Claim 10
Dependent Claim
24 words
A magnetic recording medium according to claim 8, wherein said magnetic particles have a coercive force (Hc) in the vertical direction of 1250 oersteds.
Claim 11
Dependent Claim
89 words
A magnetic recording medium which comprises a substrate and a magnetic layer thereon, said magnetic layer containing acicular magnetic metal particles, having a particle size of not more than 0.3μ, a squareness ratio in the vertical direction of said layer of 0.60, a squareness ratio in the lengthwise direction of said layer being 0.62, a coercive force (Hc) in the lengthwise direction of 1360 oersteds, a coercive force (Hc) in the vertical direction of 1250 oersteds, a residual magnetic flux density of 1920 and a orientation ratio of 0.97.
Claim 12
Dependent Claim
89 words
A magnetic recording medium which comprises a substrate and a magnetic layer thereon, said magnetic layer containing acicular magnetic metal particles, having a particle size of not more than 0.3μ, a squareness ratio in the vertical direction of said layer of 0.60, a squareness ratio in the lengthwise direction of said layer being 0.62, a coercive force (Hc) in the lengthwise direction of 1360 oersteds, a coercive force (Hc) in the vertical direction of 1250 oersteds, a residual magnetic flux density of 1920 and a orientation ratio of 0.97.
Claim 13
Dependent Claim
83 words
A magnetic recording medium which comprises a substrate and a magnetic layer thereon, said magnetic layer containing acicular magnetic metal particles, having a particle size of not more than 0.3μ, a squareness ratio in the vertical direction of 0.72, a squareness ratio in the lengthwise direction of 0.57, a coercive force (Hc) in the vertical direction of 1290 oersteds, a coercive force (Hc) in the lengthwise direction of 1200 oersteds, a residual magnetic flux density of 2310, and an orientation ratio of 1.26.
Claim 14
Dependent Claim
83 words
A magnetic recording medium which comprises a substrate and a magnetic layer thereon, said magnetic layer containing acicular magnetic metal particles, having a particle size of not more than 0.3μ, a squareness ratio in the vertical direction of 0.72, a squareness ratio in the lengthwise direction of 0.57, a coercive force (Hc) in the vertical direction of 1290 oersteds, a coercive force (Hc) in the lengthwise direction of 1200 oersteds, a residual magnetic flux density of 2310, and an orientation ratio of 1.26.
Claim 15
Dependent Claim
15 words
The magnetic recording medium of claim 1, wherein said magnetic particles comprise iron oxide particles.
Claim 16
Dependent Claim
19 words
The magnetic recording medium of claim 12, wherein said iron oxide particles contain small amounts of cobalt and nickel.
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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) | 1987-10-30 | 1988-04-30 | 1988-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-30 | 1992-04-30 | 1992-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-30 | 1996-04-30 | 1996-10-30 | $7700.00 | Window Closed / Lapsed |