US4393110A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
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Filing: 1982-01-20
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Granted: 1983-07-12
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Expires: 2002-01-20
Abstract
Abstract A magnetic recording medium comprising a non-magnetic substrate having fine holes in a direction of thickness and a magnetic material filled in said fine holes. The fine holes have a diameter ranging from 200 A to 5000 A and a depth ranging from 2000 A to 5 μm at a ratio of depth to diameter of 1 or more.
Inventors
- 👤 Kazumasa Fukuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:22
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/855; G11B5/62; G11B5/68; G11B5/70; G11B5/716; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24479; Y10T428/24612; Y10T428/2462; Y10T428/26; Y10T428/268
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
69 words
In a magnetic recording medium having a high density of magnetic recording including a non-magnetic substrate having fine holes in a direction of thickness and a magnetic material filled in said fine holes, an improvement wherein said fine holes have a diameter ranging from 200 Angstroms to 5000 Angstroms and a depth ranging from 2000 Angstroms to 5 microns at a ratio of depth to diameter of substantially 10.
Claim 2
Dependent Claim
69 words
In a magnetic recording medium having a high density of magnetic recording including a non-magnetic substrate having fine holes in a direction of thickness and a magnetic material filled in said fine holes, an improvement wherein said fine holes have a diameter ranging from 200 Angstroms to 5000 Angstroms and a depth ranging from 2000 Angstroms to 5 microns at a ratio of depth to diameter of substantially 10.
Claim 3
Dependent Claim
34 words
The magnetic recording medium according to claim 1 wherein said fine holes have a surface density of said holes ranging from 1.6×10 7 holes/cm 2 to 1.6×10 11 holes/cm 2 on said non-magnetic substrate.
References Cited (Backward Citations)
US4117301A
Cited
US4131782A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-11 | 1987-01-10 | 1987-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-11 | 1991-01-10 | 1991-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-11 | 1995-01-10 | 1995-07-12 | $7700.00 | Window Closed / Lapsed |