US4777082A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical magnetic recording medium
Assignee: TDK Corp
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Filing: 1987-08-17
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Granted: 1988-10-11
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Expires: 2007-08-17
Abstract
Abstract In an optical recording medium comprising a substrate and a recording layer thin film comprised of a rare earth element and a transition metal, for example, TbFeCo on the substrate, a metal thin film layer having a high magnetic permeability, for example, Permalloy is formed on the recording layer. A transparent dielectric film layer may be formed between the substrate and the recording layer thin film.
Inventors
- 👤 Hideki Ishizaki
- 👤 Takayoshi Kobuke
- 👤 Suguru Takayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:08
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12771; Y10T428/12861; Y10T428/12931; Y10T428/12937; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/24975
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
95 words
An optical magnetic recording medium comprising a substrate, a recording layer thin film comprised of a rare earth element and a transition metal on the substrate, and a metal thin film layer having a high magnetic permeability on the recording layer, wherein the recording layer thin film is at least 5 nm thick, the metal thin film layer is at least 20 nm thick, and wherein the total thickness of the recording layer thin film and the metal thin film layer ranges from 50 to 200 nm wherein said metal thin film layer is permalloy.
Claim 2
Dependent Claim
95 words
An optical magnetic recording medium comprising a substrate, a recording layer thin film comprised of a rare earth element and a transition metal on the substrate, and a metal thin film layer having a high magnetic permeability on the recording layer, wherein the recording layer thin film is at least 5 nm thick, the metal thin film layer is at least 20 nm thick, and wherein the total thickness of the recording layer thin film and the metal thin film layer ranges from 50 to 200 nm wherein said metal thin film layer is permalloy.
Claim 3
Dependent Claim
24 words
The optical recording medium of claim 1 which further comprises a transparent dielectric film layer between the substrate and the recording layer thin film.
References Cited (Backward Citations)
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US4489139A
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JPS5841451A
Cited
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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) | 1991-10-11 | 1992-04-11 | 1992-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-11 | 1996-04-11 | 1996-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-11 | 2000-04-11 | 2000-10-11 | $7700.00 | Window Closed / Lapsed |