EP0451297A1
Expired / Lapsed
EP
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Pretreatment of overwritable opto-magnetic recording medium and pretreated overwritable opto-magnetic recording medium
Assignee: Nikon Corp
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Filing: 1990-10-31
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Granted: —
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Expires: 2010-10-31
Abstract
Abstract A method of pretreating an overwritable opto-magnetic recording medium disc by modulating merely the intensity of an optical beam without modulating the direction of a recording magnetic field. The opto-magnetic recording medium comprises at least a multilayered vertically magnetized film having a two-layered structure of a recording layer (first layer) and a recording assisting layer (second layer). Data are recorded in the first layer (and also in the second layer, at times) by applying a laser beam to the recording medium in the form of bits having "A direction" magnetization and bits having "direction opposite to A" magnetization. When the intensity of the laser beam is on a high level, "A direction" magnetization of the recording assisting layer (second layer) is reversed to "direction opposite to A" magnetization by the recording magnetic field Hb so as to form the bits having "direction opposite to A" magnetization (or "A direction" magnetization) in the recording layer (first layer) by "direction opoposite to A" magnetization of this second layer. When the beam intensity is on a low level, bits having "A direction magnetization" (or "direction opposite to A" direction) are formed in the first layer by "A direction" magnetization of the second layer.
Inventors
- 👤 Haruhisa Iida
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 17:27
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10502; G11B11/10526; G11B11/10504; G11B11/10506; G11B11/10517; G11B11/10519; G11B19/00; G11B19/02; G11B19/12
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
168 words
Method of pre-processing comprising: (a) a first step of preparing a magnetooptical recording medium being over-write capable by beam intensity modulation, the medium having at least two-layered structure including a recording layer having a perpendicular magnetic unisotopy and a reference layer having a perpendicular magnetic unisotopy and exchange-coupled to the recording layer, and a direction of magnetization of the reference layer of the medium can be aligned in a first direction without changing a direction of magnetization of the recording layer, the medium having a plurality of tracks in which information is recorded and a separation tone being formed between adjacent tracks; and (b) a second step of aligning a direction of magnetization of the recording layer in the separation zone in a second direction by application of a pre-processing field so as to prevent, when a direction of magnetization of said reference layer is aligned in said first direction, a generation of a magnetic wall between the recording layer and the reference layer in the separation zone.
Claim 2
Dependent Claim
168 words
Method of pre-processing comprising: (a) a first step of preparing a magnetooptical recording medium being over-write capable by beam intensity modulation, the medium having at least two-layered structure including a recording layer having a perpendicular magnetic unisotopy and a reference layer having a perpendicular magnetic unisotopy and exchange-coupled to the recording layer, and a direction of magnetization of the reference layer of the medium can be aligned in a first direction without changing a direction of magnetization of the recording layer, the medium having a plurality of tracks in which information is recorded and a separation tone being formed between adjacent tracks; and (b) a second step of aligning a direction of magnetization of the recording layer in the separation zone in a second direction by application of a pre-processing field so as to prevent, when a direction of magnetization of said reference layer is aligned in said first direction, a generation of a magnetic wall between the recording layer and the reference layer in the separation zone.
Claim 3
Dependent Claim
24 words
A method according to claim 1, wherein said medium is of parallel type, and said first direction and said second direction are the same.
Claim 4
Dependent Claim
23 words
A method according to claim 1, wherein said medium is of anti-parallel type, and said first direction and said second direction are opposite.
Claim 5
Dependent Claim
15 words
A method according to claim 1, wherein said medium is heated during said second step.
Claim 6
Dependent Claim
41 words
A method according to claim 1, further comprising; (c) a third step of making an indication on said medium, the indication indicating that the direction of magnetization of said recording layer in said separation zone is aligned in said second direction.
Claim 7
Dependent Claim
43 words
A method according to claim 1, further comprising (c) a third step of making an indication on a case containing said medium, the indication indicating that the direction of magnetization of said recording layer in said separation zone is aligned in second direction.
Claim 8
Dependent Claim
31 words
A method according to claim 1, further comprising, after said second step, (d) a fourth step of aligning the direction of magnetization in said first direction by application of initial field.
Claim 9
Dependent Claim
160 words
A magnetooptical recording medium being over-write capable by means intensity modulation, the medium having at least two-layered structure including a recording layer having a perpendicular magnetic unisotopy and a reference layer having a perpendicular magnetic unisotopy and exchange coupled to the recording layer, and a direction of magnetization of the reference layer of the medium can be aligned in a first direction without changing a direction of magnetization of the recording layer, the medium having a plurality of tracks in which information is recorded, and a separation zone being formed between adjacent tracks, and the medium having undergone pre-processing in which pre-processing field is applied to the medium with or without heating so as to align a direction of magnetization in the separation zone in a second direction in order that, when a direction of magnetization is aligned in the first direction, a magnetic wall between the recording layer and the reference layer is not generated in the separation zone.
Claim 10
Dependent Claim
160 words
A magnetooptical recording medium being over-write capable by means intensity modulation, the medium having at least two-layered structure including a recording layer having a perpendicular magnetic unisotopy and a reference layer having a perpendicular magnetic unisotopy and exchange coupled to the recording layer, and a direction of magnetization of the reference layer of the medium can be aligned in a first direction without changing a direction of magnetization of the recording layer, the medium having a plurality of tracks in which information is recorded, and a separation zone being formed between adjacent tracks, and the medium having undergone pre-processing in which pre-processing field is applied to the medium with or without heating so as to align a direction of magnetization in the separation zone in a second direction in order that, when a direction of magnetization is aligned in the first direction, a magnetic wall between the recording layer and the reference layer is not generated in the separation zone.
Claim 11
Dependent Claim
23 words
A medium according to claim 8, wherein said first direction is indicated on said medium itself or on a case containing said medium.
Claim 12
Dependent Claim
23 words
A medium according to claim 8, wherein said second direction is indicated on said medium itself or on a case containing said medium.
References Cited (Backward Citations)
No citation records indexed.
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