US5210724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optomagnetic recording method and apparatus which precludes an interface magnetic wall within block magnetic wall
Assignee: Canon Inc
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Filing: 1991-12-10
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Granted: 1993-05-11
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Expires: 2011-12-10
Abstract
Abstract An information recording method, which performs recording of an information by use of an optical magnetic recording medium provided with a first magnetic layer and a second magnetic layer having higher Curie point and lower coercive force at room temperature than the first magnetic layer, by carrying out initialization to align the magnetization direction of the second magnetic layer in one direction and then irradiating an optical beam of which power has received modulation between the two values which are not zero depending on the information, thereby recording the information as the arrangement of a magnetic domain on the above medium, has characteristic such that, when initialized again after recording of the above information, an interface magnetic wall is permitted to exist between said first and second magnetic layers at the portion other than said magnetic domain.
Inventors
- 👤 Tadashi Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:49
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10502; G11B11/10504; G11B11/10506; G11B11/10523; G11B11/10582; G11B11/10586
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
165 words
A method of magneto-optical recording information comprising the steps of: using an optical-magnetic recording medium including a first magnetic layer and a second magnetic layer having a higher Curie point and lower coercive force at room temperature than that of said first magnetic layer; initializing said medium to align the magnetization direction of said second magnetic layer in one direction; irradiating said medium with an optical beam that is modulated with information to be recorded on the medium between two non-zero values, to thereby record the information in the form of magnetic domains onto the medium; and re-initializing after said recording of said information, wherein the medium is formed in such a way that during said re-initializing: (i) no interface magnetic wall exists between said first and second magnetic layers inside each of said magnetic domains which is surrounded by Bloch magnetic walls, and (ii) an interface magnetic wall exists between said first and second magnetic layers at portions other than said recorded magnetic domains.
Claim 2
Independent Claim
165 words
A method of magneto-optical recording information comprising the steps of: using an optical-magnetic recording medium including a first magnetic layer and a second magnetic layer having a higher Curie point and lower coercive force at room temperature than that of said first magnetic layer; initializing said medium to align the magnetization direction of said second magnetic layer in one direction; irradiating said medium with an optical beam that is modulated with information to be recorded on the medium between two non-zero values, to thereby record the information in the form of magnetic domains onto the medium; and re-initializing after said recording of said information, wherein the medium is formed in such a way that during said re-initializing: (i) no interface magnetic wall exists between said first and second magnetic layers inside each of said magnetic domains which is surrounded by Bloch magnetic walls, and (ii) an interface magnetic wall exists between said first and second magnetic layers at portions other than said recorded magnetic domains.
Claim 3
Independent Claim
175 words
A method of magneto-optical recording information comprising the steps of: using an optical magnetic recording medium comprising a first magnetic layer and a second magnetic layer, said second magnetic layer having a higher Curie point and a lower coercive force at room temperature than said first magnetic layer; initializing said medium to align the magnetization direction of said second magnetic layer in one direction; and irradiating said medium with an optical beam that is modulated with information to be recorded on the medium between two non-zero values, to thereby record the information in the form of magnetic domains onto the medium, whereby when the recording medium is reinitialized after said recording of information, the medium is formed in such a way that during said reinitializing: (i) no interface magnetic wall will exist between said first and second magnetic layers inside each of said magnetic domains which is surrounded by Bloch magnetic walls, and (ii) an interface magnetic wall will exist between said first and second magnetic layers at portions other than said recorded magnetic domains.
Claim 4
Independent Claim
175 words
A method of magneto-optical recording information comprising the steps of: using an optical magnetic recording medium comprising a first magnetic layer and a second magnetic layer, said second magnetic layer having a higher Curie point and a lower coercive force at room temperature than said first magnetic layer; initializing said medium to align the magnetization direction of said second magnetic layer in one direction; and irradiating said medium with an optical beam that is modulated with information to be recorded on the medium between two non-zero values, to thereby record the information in the form of magnetic domains onto the medium, whereby when the recording medium is reinitialized after said recording of information, the medium is formed in such a way that during said reinitializing: (i) no interface magnetic wall will exist between said first and second magnetic layers inside each of said magnetic domains which is surrounded by Bloch magnetic walls, and (ii) an interface magnetic wall will exist between said first and second magnetic layers at portions other than said recorded magnetic domains.
Claim 5
Dependent Claim
77 words
An information recording method according to claims 1 or 2, wherein said first and second magnetic layers satisfy ##EQU1## wherein H H is a high coercive force of the first magnetic layer, H L is a low coercive force of the second magnetic layer, Ms is a saturated magnetization of the second magnetic layer, h is a thickness of the second magnetic layer, and σω is a magnetic wall energy between the first and second magnetic layers.
Claim 6
Independent Claim
44 words
A method according to claims 1 or 2, wherein a third magnetic layer is provided for controlling the energy of the interface magnetic wall between said first and second magnetic layers, said third magnetic layer being arranged between said first and second magnetic layers.
Claim 7
Dependent Claim
17 words
An information recording method according to claim 4, wherein said magnetization film is a vertical magnetization film.
Claim 8
Dependent Claim
17 words
An information recording method according to claim 4, wherein said magnetization film is an interplanar magnetization film.
Claim 9
Independent Claim
24 words
A method according to claims 1 or 2, wherein said first and second magnetic layers comprise a rare earth-transition metal amorphous alloy thin film.
Claim 10
Dependent Claim
35 words
An information recording method according to claim 7, wherein a magnetization film with small magnetic wall energy is provided for controlling the energy of the interface magnetic wall between said first and second magnetic layers.
Claim 11
Dependent Claim
17 words
An information recording method according to claim 8, wherein said magnetization film is a vertical magnetization film.
Claim 12
Dependent Claim
17 words
An information recording method according to claim 8, wherein said magnetization film is an interplanar magnetization film.
References Cited (Backward Citations)
US3521294A
Cited
US3996571A
Cited
US4151602A
Cited
US4198692A
Cited
US4612587A
Cited
DE3619618A1
Cited
JPS62175948A
Cited
US4771347A
Cited
JPS63153752A
Cited
US4855975A
Cited
JPS63133338A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-05-10 | 1996-11-09 | 1997-05-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-05-10 | 2000-11-09 | 2001-05-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-05-10 | 2004-11-09 | 2005-05-11 | $7700.00 | Window Closed / Lapsed |