Patent US2124951A successfully refreshed from Google Patents.
US4624883A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Maxell Ltd
•
Filing: 1984-03-19
•
Granted: 1986-11-25
•
Expires: 2004-03-19
Abstract
Abstract A magnetic recording medium which comprises a first magnetic layer on a base and a second magnetic layer over the first magnetic layer, the second magnetic layer containing magnetic particles having an average particle length (long axis diameter) of not more than 0.35 mu , with a coercive force of from 660 to 760 oersteds, and the ratio of the coercive force of the upper or second magnetic layer to that of the lower or first magnetic layer being 1.1/1 to 1.6/1. The resulting magnetic recording medium has excellent sensitivity and frequency characteristics over the entire frequency bands with less noise.
Inventors
- 👤 Satoru Yamaguchi
- 👤 Kozaburoh Satoh
- 👤 Jozo Shimizu
- 👤 Haruo Andoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:40
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; Y10T428/2495; Y10T428/24967; Y10T428/24975; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
96 words
A magnetic recording medium for audio recording which comprises a base, a lower magnetic layer containing magnetic particles having an average particle length (long axis diameter) of from 0.4 to 0.7μ provided on said base, and an upper magnetic layer containing magnetic particles having an average particle length (long axis diameter) of not more than 0.35μ provided over said lower magnetic layer, the coercive force of said upper magnetic layer being from 660 to 760 oersteds, the ratio of the coercive force of the upper layer to that of the lower layer being 1.2/1 to 1.5/1.
Claim 2
Dependent Claim
96 words
A magnetic recording medium for audio recording which comprises a base, a lower magnetic layer containing magnetic particles having an average particle length (long axis diameter) of from 0.4 to 0.7μ provided on said base, and an upper magnetic layer containing magnetic particles having an average particle length (long axis diameter) of not more than 0.35μ provided over said lower magnetic layer, the coercive force of said upper magnetic layer being from 660 to 760 oersteds, the ratio of the coercive force of the upper layer to that of the lower layer being 1.2/1 to 1.5/1.
Claim 3
Dependent Claim
23 words
A magnetic recording medium according to claim 1, wherein the coercive force of said upper magnetic layer is from 680 to 740 oersteds.
Claim 4
Dependent Claim
37 words
A magnetic recording medium according to claim 1, wherein said upper magnetic layer contains magnetic particles having an average magnetic layer contains magnetic particles having an average particle length (long axis diameter) of from 0.15 to 0.35μ.
Claim 5
Dependent Claim
26 words
The audio magnetic recording medium of claim 1, wherein a combined total thickness of the lower and upper magnetic layers ranges from 5.0 to 5.5 microns.
Claim 6
Dependent Claim
32 words
The audio magnetic recording medium 1, wherein thickness of said upper magnetic layer is from 1.5 to 3.0 microns and thickness of said lower magnetic layer is from 2.5 to 4.0 microns.
Claim 7
Dependent Claim
32 words
The audio magnetic recording medium 1, wherein thickness of said upper magnetic layer is from 1.5 to 3.0 microns and thickness of said lower magnetic layer is from 2.5 to 4.0 microns.
References Cited (Backward Citations)
US4265931A
Cited
US4200678A
Cited
US4246316A
Cited
JPS5448504A
Cited
US4323621A
Cited
GB2042370A
Cited
US4409281A
Cited
JPS5769528A
Cited
US4410590A
Cited
US4439796A
Cited
US4439795A
Cited
JPS57143734A
Cited
US4513054A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-11-24 | 1990-05-26 | 1990-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-24 | 1994-05-26 | 1994-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-24 | 1998-05-26 | 1998-11-25 | $7700.00 | Window Closed / Lapsed |