US4741953A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Maxell Ltd
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Filing: 1986-03-20
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Granted: 1988-05-03
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Expires: 2006-03-20
Abstract
Abstract A magnetic recording medium having a broad dynamic range over an entire range of frequency which comprises a substrate material and a magnetic layer comprising magnetic particles and a resinous binder provided on at least one of the surfaces of the substrate material, characterized in that the magnetic layer is constructed as a double layered structure comprising an upper layer and a lower layer and which satisfies the following requirements: H1>H2 (1) r1<r2 (2) wherein H1 is the coercive force of the upper layer, H2 is the coercive force of the lower layer, r1 is the average size of the long axis of magnetic particles in the upper layer and r2 is the average size of the long axis of magnetic particles in the lower layer, and the lower layer comprises as the magnetic particles iron oxide magnetic particles having a particle void content of not more than 5% by volume in average.
Inventors
- 👤 Yoshiharu Katsuta
- 👤 Haruo Ando
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:56
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/714; G11B5/716; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
151 words
A magnetic recording medium which comprises a substrate material and a magnetic layer provided on at least one of the surfaces of said substrate material, said magnetic layer comprising a two layered structure including an upper layer and a lower layer of magnetic particles and a resinous binder, said magnetic layer satisfying the following requirements: H.sub.1 >H.sub.2 ( 1) r.sub.1 <r.sub.2 ( 2) wherein H 1 is the coercive force of the upper layer, H 2 is the coercive force of the lower layer, r 1 is the average size of the long axis of the magnetic particles in the upper layer and r 2 is the average size of the long axis of the magnetic particles in the lower layer, and wherein only the lower layer comprises magnetic particles having a particle void content of not more than an average of 5% by volume, said magnetic particles comprising iron oxide.
Claim 2
Dependent Claim
151 words
A magnetic recording medium which comprises a substrate material and a magnetic layer provided on at least one of the surfaces of said substrate material, said magnetic layer comprising a two layered structure including an upper layer and a lower layer of magnetic particles and a resinous binder, said magnetic layer satisfying the following requirements: H.sub.1 >H.sub.2 ( 1) r.sub.1 <r.sub.2 ( 2) wherein H 1 is the coercive force of the upper layer, H 2 is the coercive force of the lower layer, r 1 is the average size of the long axis of the magnetic particles in the upper layer and r 2 is the average size of the long axis of the magnetic particles in the lower layer, and wherein only the lower layer comprises magnetic particles having a particle void content of not more than an average of 5% by volume, said magnetic particles comprising iron oxide.
Claim 3
Dependent Claim
18 words
The magnetic recording medium according to claim 1, wherein H 1 /H 2 is not less than 1.1.
Claim 4
Dependent Claim
18 words
The magnetic recording medium according to claim 1, wherein r 2 /r 1 is not less than 1.2.
Claim 5
Dependent Claim
19 words
The magnetic recording medium according to claim 1, wherein H 1 /H 2 is from about 1.1 to 1.4
Claim 6
Dependent Claim
19 words
The magnetic recording medium according to claim 1, wherein r 2 /r 1 is from about 1.4 to 3.0.
Claim 7
Dependent Claim
36 words
The magnetic recording medium according to claim 1, wherein the average size of the long axis of the magnetic particles in said lower layer of said two layered structure is from about 0.2 to 0.6 micron.
Claim 8
Dependent Claim
41 words
The magnetic recording medium according to claim 1, wherein: m 2 is equal to or larger than m 1 , in which m 2 is the thickness of the lower layer and m 1 is the thickness of the upper layer.
Claim 9
Dependent Claim
18 words
The magnetic recording medium according to claim 7, wherein m 2 /m 1 is not less than 1.0.
Claim 10
Dependent Claim
19 words
The magnetic recording medium according to claim 7, wherein m 2 /m 1 is from about 1.1 to 4.0.
Claim 11
Dependent Claim
19 words
The magnetic recording medium according to claim 7, wherein m 2 is within a range of 1.0 to 3.0microns.
Claim 12
Dependent Claim
23 words
The magnetic recording medium according to claim 7, wherein (m 2 +m 1 ) is within a range of 3.5 to 7.0 microns.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-03 | 1991-11-02 | 1992-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-03 | 1995-11-02 | 1996-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-03 | 1999-11-02 | 2000-05-03 | $7700.00 | Window Closed / Lapsed |