EP0318925A2
Expired / Lapsed
EP
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Method for optically reproducing a signal from magneto-optical recording medium
Assignee: Sony Corp
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Filing: 1988-11-29
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Granted: —
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Expires: 2008-11-29
Abstract
Abstract A method of reproducing a signal from a magneto-optical recording medium is disclosed in which the medium is formed of a first magnetic film (11), a second magnetic film (12) and a third magnetic film (13) magnetically coupled to one another at room temperature T RT , wherein the Curie points Tc1, Tc2 and Tc3 of the first, second and third magnetic films are in the relationship of Tc2 > T RT , Tc2 < Tc1, and Tc2 < Tc3, and the coercive force Hc1 of the first magnetic film (11) is sufficiently small in the vicinity of the Curie point Tc2 of the second magnetic film (12), while the coercive force Hc3 of the third magnetic film (13) is sufficiently greater than a required magnetic field intensity within a temperature range between the room temperature T RT and a predetermined temperature T PB higher than the Curie point Tc2 of the second magnetic film. In reproducing a signal from the magneto-optical recording medium, the medium is heated to the predetermined temperature T PB to interrupt the magnetic coupling between the first (11) and third magnetic film (12) under an application of magnetic field to cause change of domain size in said first magnetic film (11), thus providing higher resolution of signal and improved S/N to enable high density recording.
Inventors
- 👤 Katsuhisa Aratani
- 👤 Minoru Kohno
- 👤 Kenjiro Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 13:02
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10502; G11B11/10528; G11B11/10515
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
193 words
A method of reproducing a signal from a magneto-optical recording medium having a first magnetic film (11), a second magnetic film (12) and a third magnetic film (13) magnetically coupled to one another at room temperature T RT , wherein the Curie points Tc1, Tc2 and Tc3 of said first, second and third magnetic films are in the relationship of Tc2 > T RT , Tc2 < Tc1, and Tc2 < Tc3, and the coercive force Hc1 of said first magnetic film is sufficiently small in the vicinity of the Curie point Tc2 of said second magnetic film, while the coercive force Hc3 of said third magnetic film is sufficiently greater than a required magnetic field intensity within a temperature range between said room temperature T RT and a predetermined temperature T PB higher than the Curie point Tc2 of said second magnetic film, and in reproducing a signal from said magneto-optical recording medium, said medium is heated to said predetermined temperature T PB to interrupt the magnetic coupling between said first and third magnetic film under an application of magnetic field to cause change of domain size in said first magnetic film.
Claim 2
Independent Claim
193 words
A method of reproducing a signal from a magneto-optical recording medium having a first magnetic film (11), a second magnetic film (12) and a third magnetic film (13) magnetically coupled to one another at room temperature T RT , wherein the Curie points Tc1, Tc2 and Tc3 of said first, second and third magnetic films are in the relationship of Tc2 > T RT , Tc2 < Tc1, and Tc2 < Tc3, and the coercive force Hc1 of said first magnetic film is sufficiently small in the vicinity of the Curie point Tc2 of said second magnetic film, while the coercive force Hc3 of said third magnetic film is sufficiently greater than a required magnetic field intensity within a temperature range between said room temperature T RT and a predetermined temperature T PB higher than the Curie point Tc2 of said second magnetic film, and in reproducing a signal from said magneto-optical recording medium, said medium is heated to said predetermined temperature T PB to interrupt the magnetic coupling between said first and third magnetic film under an application of magnetic field to cause change of domain size in said first magnetic film.
Claim 3
Independent Claim
177 words
A method of reproducing a signal from a magneto-optical recording medium having a first magnetic film, a second magnetic film and a third magnetic film magnetically coupled to one another at room temperature T RT , wherein the Curie points Tc1, Tc2 and Tc3 of said first, second and third magnetic films are in the relationship of Tc2 > T RT and Tc2 < Tc1, and Tc2 < Tc3, and the coercive force Hc1 of said first magnetic film is sufficiently small in the vicinity of the Curie point Tc2 of said second magnetic film, while the coercive force Hc3 of said third magnetic film is sufficiently greater than a required magnetic field intensity within a temperature range between said room temperature T RT and a predetermined temperature T PB higher than the Curie point Tc2 of said second magnetic film, and in reproducing signal from said magneto-optical recording medium, said medium is heated upon said predetermined temperature under an application of magnetic field to said first magnetic film to cause the shrink of recorded magnetic domain.
Claim 4
Independent Claim
177 words
A method of reproducing a signal from a magneto-optical recording medium having a first magnetic film, a second magnetic film and a third magnetic film magnetically coupled to one another at room temperature T RT , wherein the Curie points Tc1, Tc2 and Tc3 of said first, second and third magnetic films are in the relationship of Tc2 > T RT and Tc2 < Tc1, and Tc2 < Tc3, and the coercive force Hc1 of said first magnetic film is sufficiently small in the vicinity of the Curie point Tc2 of said second magnetic film, while the coercive force Hc3 of said third magnetic film is sufficiently greater than a required magnetic field intensity within a temperature range between said room temperature T RT and a predetermined temperature T PB higher than the Curie point Tc2 of said second magnetic film, and in reproducing signal from said magneto-optical recording medium, said medium is heated upon said predetermined temperature under an application of magnetic field to said first magnetic film to cause the shrink of recorded magnetic domain.
Claim 5
Independent Claim
177 words
A method of reproducing a signal from a magneto-optical recording medium having a first magnetic film, a second magnetic film and a third magnetic film magnetically coupled to one another at room temperature T RT , wherein the Curie points Tc1, Tc2 and Tc3 of said first, second and third magnetic films are in the relationship of Tc2 > T RT and Tc2 < Tc1, and Tc2 < Tc3, and the coercive force Hc1 of said first magnetic film is sufficiently small in the vicinity of the Curie point Tc2 of said second magnetic film, while the coercive force Hc3 of said third magnetic film is sufficiently greater than a required magnetic field intensity within a temperature range between said room temperature T RT and a predetermined temperature T PB higher than the Curie point Tc2 of said second magnetic film, and in reproducing a signal from said magneto-optical recording medium, said medium is heated upon said predetermined temperature T PB under an application of magnetic field to said first magnetic film to expand recorded magnetic domain.
Claim 6
Independent Claim
177 words
A method of reproducing a signal from a magneto-optical recording medium having a first magnetic film, a second magnetic film and a third magnetic film magnetically coupled to one another at room temperature T RT , wherein the Curie points Tc1, Tc2 and Tc3 of said first, second and third magnetic films are in the relationship of Tc2 > T RT and Tc2 < Tc1, and Tc2 < Tc3, and the coercive force Hc1 of said first magnetic film is sufficiently small in the vicinity of the Curie point Tc2 of said second magnetic film, while the coercive force Hc3 of said third magnetic film is sufficiently greater than a required magnetic field intensity within a temperature range between said room temperature T RT and a predetermined temperature T PB higher than the Curie point Tc2 of said second magnetic film, and in reproducing a signal from said magneto-optical recording medium, said medium is heated upon said predetermined temperature T PB under an application of magnetic field to said first magnetic film to expand recorded magnetic domain.
Claim 7
Independent Claim
22 words
A method according to claims 1, 2 or 3, signal is obtained by detecting signal change upon change of the domain size.
References Cited (Backward Citations)
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