Patent US2842082A successfully refreshed from Google Patents.
US4897320A
Expired / Lapsed
US
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Magneto-optical recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1988-08-11
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Granted: 1990-01-30
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Expires: 2008-08-11
Abstract
Abstract A magneto-optical recording medium comprises a recording layer formed of a magnetic material, and a protective layer composed of a combination of a dielectric material with a rare earth metal exhibiting a high oxygen absorptivity and formed on the recording layer by a simultaneous sputtering or a simultaneous deposition process, whereby free oxygen given rise to in the course of sputtering or deposition is absorbed on the protective layer side before being absorbed on the recording layer side.
Inventors
- 👤 Masaaki Nomura
- 👤 Takashi Yamada
- 👤 Ryoichi Yamamoto
- 👤 Akira Nahara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:27
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
106 words
A magneto-optical recording medium comprising a transparent nonmagnetic substrate, a magneto-optical recording layer overlaid on said transparent nonmagnetic substrate, and a protective layer overlaid on said magneto-optical recording layer, wherein said protective layer is composed of a layer of a mixture of a rare earth metal with a dielectric material, the content of the rare earth metal in the mixture of the protective layer being within the range of 15-45 percent by volume; whereby free oxygen given rise to in the course of sputtering or deposition of said protective layer is absorbed on the protective layer said before it can be absorbed on the recording layer.
Claim 2
Dependent Claim
106 words
A magneto-optical recording medium comprising a transparent nonmagnetic substrate, a magneto-optical recording layer overlaid on said transparent nonmagnetic substrate, and a protective layer overlaid on said magneto-optical recording layer, wherein said protective layer is composed of a layer of a mixture of a rare earth metal with a dielectric material, the content of the rare earth metal in the mixture of the protective layer being within the range of 15-45 percent by volume; whereby free oxygen given rise to in the course of sputtering or deposition of said protective layer is absorbed on the protective layer said before it can be absorbed on the recording layer.
Claim 3
Dependent Claim
25 words
A magneto-optical recording medium as defined in claim 1 wherein said protective layer is formed by a simultaneous sputtering process or a simultaneous deposition process.
Claim 4
Dependent Claim
25 words
A magneto-optical recording medium as defined in claim 1 wherein said rare earth metal is in the form of an alloy with a transition metal.
Claim 5
Dependent Claim
96 words
A magneto-optical recording medium comprising a transparent nonmagnetic substrate, a first protective layer overlaid on said transparent nonmagnetic substrate, a magneto-optical recording layer disposed on said first protective layer, and a second protective layer disposed on said magneto-optical recording layer, wherein said first and second protective layers are composed of a layer of a mixture of a rare earth metal with a dielectric material whereby free oxygen, given rise to during sputtering or deposition of said first and second protective layers, is absorbed on said protective layers before it can be absorbed on the recording layer.
Claim 6
Dependent Claim
96 words
A magneto-optical recording medium comprising a transparent nonmagnetic substrate, a first protective layer overlaid on said transparent nonmagnetic substrate, a magneto-optical recording layer disposed on said first protective layer, and a second protective layer disposed on said magneto-optical recording layer, wherein said first and second protective layers are composed of a layer of a mixture of a rare earth metal with a dielectric material whereby free oxygen, given rise to during sputtering or deposition of said first and second protective layers, is absorbed on said protective layers before it can be absorbed on the recording layer.
Claim 7
Dependent Claim
35 words
A magneto-optical recording medium as defined in claim 4 wherein said rare earth metal and dielectric material of said first and second layers are deposited by a simultaneous sputtering process or a simultaneous deposition process.
Claim 8
Dependent Claim
25 words
A magneto-optical recording medium as defined in claim 4 wherein said rare earth metal is in the form of an alloy with a transition metal.
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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) | 1993-01-29 | 1993-07-31 | 1994-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-29 | 1997-07-31 | 1998-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-29 | 2001-07-31 | 2002-01-30 | $7700.00 | Window Closed / Lapsed |