US4837118A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magneto-optical recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1987-05-11
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Granted: 1989-06-06
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Expires: 2007-05-11
Abstract
Abstract A magneto-optical recording medium comprises a transparent substrate and a magneto-optical recording layer overlaid on the transparent substrate. The magneto-optical recording layer is formed by alternately overlaying a plurality of thin layers containing a rare earth metal-transition metal alloy for magneto-optical recording, and a plurality of thin layers containing at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper, and iridium which are solid solution non-formable metals.
Inventors
- 👤 Ryoichi Yamamoto
- 👤 Masaaki Nomura
- 👤 Takashi Yamada
- 👤 Akira Nahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 06:59
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; G11B11/10591; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12701; Y10T428/12729; Y10T428/12771; Y10T428/12861; Y10T428/12889; Y10T428/12896; Y10T428/12903; Y10T428/1291; Y10T428/12917
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
68 words
A magneto-optical recording medium comprising a transparent substrate and a magneto-optical recording layer overlaid on said transparent substrate wherein said magneto-optical recording layer is formed by alternately overlaying a plurality of thin layers containing a rare earth metal transition metal alloy, and a plurality of thin layers containing at least one solid solution non-formable metal selected from the group consisting of gold, silver, lead, magnesium, copper and iridium.
Claim 2
Dependent Claim
68 words
A magneto-optical recording medium comprising a transparent substrate and a magneto-optical recording layer overlaid on said transparent substrate wherein said magneto-optical recording layer is formed by alternately overlaying a plurality of thin layers containing a rare earth metal transition metal alloy, and a plurality of thin layers containing at least one solid solution non-formable metal selected from the group consisting of gold, silver, lead, magnesium, copper and iridium.
Claim 3
Dependent Claim
37 words
A magneto-optical recording medium as defined in claim 1 wherein each of said thin alternating overlying layers containing a rare earth metal-transition metal alloy has a layer thickness within the range of 50 Å to 200 Å.
Claim 4
Dependent Claim
48 words
A magneto-optical recording medium as defined in claim 1 wherein each of said thin alternating overlying layers containing at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper, and iridium has a layer thickness within the range of 2 Å to 20 Å.
Claim 5
Dependent Claim
27 words
A magneto-optical recording medium as defined in claim 1 wherein said magneto-optical recording layer has a layer thickness within the range of 100 Å to 5,000 Å.
Claim 6
Dependent Claim
57 words
A magneto-optical recording medium as defined in claim 1 wherein said thin alternating overlying layers containing a rare earth metal-transition metal alloy and said thin alternating overlying layers containing at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper, and iridium are clearly bounded by each other in said magneto-optical recording layer.
Claim 7
Dependent Claim
138 words
A magneto-optical recording medium comprising a transparent substrate and a magneto-optical recording layer overlaid on said transparent substrate, wherein said magneto-optical recording layer is formed by alternately overlaying a plurality of thin layers containing a rare earth metal-transition metal alloy, and a plurality of thin layers containing at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper and iridium, wherein the content ratio of said at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper, and iridium in said thin layers containing a rare earth metal-transition metal alloy is 0%, and the content ratio of said at least one metal selected from said group in said thin layers containing at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper, and iridium is 100%.
Claim 8
Dependent Claim
138 words
A magneto-optical recording medium comprising a transparent substrate and a magneto-optical recording layer overlaid on said transparent substrate, wherein said magneto-optical recording layer is formed by alternately overlaying a plurality of thin layers containing a rare earth metal-transition metal alloy, and a plurality of thin layers containing at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper and iridium, wherein the content ratio of said at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper, and iridium in said thin layers containing a rare earth metal-transition metal alloy is 0%, and the content ratio of said at least one metal selected from said group in said thin layers containing at least one metal selected from the group consisting of gold, silver, lead, magnesium, copper, and iridium is 100%.
Claim 9
Dependent Claim
31 words
A magneto-optical recording medium as claimed in claim 1, wherein said thin alternating layers have respective thicknesses such that freely moving magnetic walls are intercepted, whereby magnetic coercive force is increased.
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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) | 1992-06-05 | 1992-12-05 | 1993-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-05 | 1996-12-05 | 1997-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-05 | 2000-12-05 | 2001-06-06 | $7700.00 | Window Closed / Lapsed |