US5644566A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magneto-optical recording medium
Assignee: Sharp Corp
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Filing: 1995-05-02
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Granted: 1997-07-01
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Expires: 2015-05-02
Abstract
Abstract An intermediate layer is formed between a memory layer and a writing layer. The intermediate layer shows in-plane magnetization at room temperature, and perpendicular magnetization within a temperature range within which the coercive force of the memory layer is lower than that of the writing layer. The Curie point of the intermediate layer is lower than that of the memory layer. Like a conventional method, light-intensity modulation overwriting is performed by irradiating laser light whose intensity has been modulated between high level and low level while applying a recording magnetic field after performing an initialization. Even when there are variations in the raised temperature by the irradiation of laser light of high level, it is possible to perform stable overwriting with light-intensity modulation by satisfactorily restraining the exchange forces between the intermediate layer and the writing layer from causing coupling.
Inventors
- 👤 Junichiro Nakayama
- 👤 Michinobu Mieda
- 👤 Hiroyuki Katayama
- 👤 Junji Hirokane
- 👤 Akira Takahashi
- 👤 Kenji Ohta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 17:52
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10502; G11B11/10517
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
137 words
A magneto-optical recording medium comprising: a memory layer showing perpendicular magnetization within a first temperature range between room temperature and a Curie point thereof; a writing layer showing perpendicular magnetization within a second temperature range between room temperature and a Curie point thereof which is higher than the Curie point of said memory layer, said writing layer having a coercive force smaller than a coercive force of said memory layer at room temperature; and an intermediate layer between said memory layer and said writing layer, said intermediate layer showing in-plane magnetization at room temperature and perpendicular magnetization within a third temperature range within which the coercive force of said memory layer is smaller than the coercive force of said writing layer, said intermediate layer having a Curie point lower than the Curie point of said memory layer.
Claim 2
Dependent Claim
137 words
A magneto-optical recording medium comprising: a memory layer showing perpendicular magnetization within a first temperature range between room temperature and a Curie point thereof; a writing layer showing perpendicular magnetization within a second temperature range between room temperature and a Curie point thereof which is higher than the Curie point of said memory layer, said writing layer having a coercive force smaller than a coercive force of said memory layer at room temperature; and an intermediate layer between said memory layer and said writing layer, said intermediate layer showing in-plane magnetization at room temperature and perpendicular magnetization within a third temperature range within which the coercive force of said memory layer is smaller than the coercive force of said writing layer, said intermediate layer having a Curie point lower than the Curie point of said memory layer.
Claim 3
Dependent Claim
78 words
The magneto-optical recording medium according to claim 1, further comprising a readout layer on a side of said memory layer on which said intermediate layer is not formed, wherein said readout layer has a Curie point higher than the Curie point of said memory layer, and shows in-plane magnetization at room temperature and perpendicular magnetization within a temperature range between a temperature higher than room temperature and a temperature lower than the Curie point of said memory layer.
Claim 4
Dependent Claim
129 words
A magneto-optical recording medium comprising: a memory layer showing perpendicular magnetization within a first temperature range between room temperature and a Curie point thereof; a writing layer showing perpendicular magnetization within a second temperature range between room temperature and a Curie point thereof which is higher than the Curie point of said memory layer, said writing layer having a coercive force smaller than a coercive force of said memory layer at room temperature; and an intermediate layer between said memory layer and said writing layer, said intermediate layer showing perpendicular magnetization within a third temperature range within which the coercive force of said memory layer is smaller than the coercive force of said writing layer and in-plane magnetization at temperatures lower than and higher than said third temperature range.
Claim 5
Dependent Claim
129 words
A magneto-optical recording medium comprising: a memory layer showing perpendicular magnetization within a first temperature range between room temperature and a Curie point thereof; a writing layer showing perpendicular magnetization within a second temperature range between room temperature and a Curie point thereof which is higher than the Curie point of said memory layer, said writing layer having a coercive force smaller than a coercive force of said memory layer at room temperature; and an intermediate layer between said memory layer and said writing layer, said intermediate layer showing perpendicular magnetization within a third temperature range within which the coercive force of said memory layer is smaller than the coercive force of said writing layer and in-plane magnetization at temperatures lower than and higher than said third temperature range.
Claim 6
Dependent Claim
26 words
The magneto-optical recording medium according to claim 3, wherein said intermediate layer is formed by a film of a GdFeCo series rare-earth and transition metal alloy.
Claim 7
Dependent Claim
78 words
The magneto-optical recording medium according to claim 3, further comprising a readout layer on a side of said memory layer on which said intermediate layer is not formed, wherein said readout layer has a Curie point higher than the Curie point of said memory layer, and shows in-plane magnetization at room temperature and perpendicular magnetization within a temperature range between a temperature higher than room temperature and a temperature lower than the Curie point of said memory layer.
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) | 2000-06-30 | 2000-12-30 | 2001-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-06-30 | 2004-12-30 | 2005-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-06-30 | 2008-12-30 | 2009-07-01 | $7700.00 | Window Closed / Lapsed |