Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam
Patent
1988-03-22
1990-03-06
Stephan, Steven L.
Dynamic information storage or retrieval
Storage or retrieval by simultaneous application of diverse...
Magnetic field and light beam
360114, 360 59, G11B 1112, G11B 1304
Patent
active
049072110
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a magneto-optical recording apparatus which is capable of rewriting information on a magneto-optical recording medium by overwriting.
BACKGROUND ART
Conventionally, there has been proposed an apparatus, the main portion of which is shown in FIG. 1 as a magneto-optical recording apparatus which is capable of rewriting information by overwriting.
In FIG. 1, reference numeral 1 designates a magneto-optical disk, and in the present example, this magneto-optical disk 1 is formed by depositing a perpendicular magnetization layer 3 on a glass substrate 2 and this magneto-optical disk 1 can be rotated with a central axis 0 - 0' as the center.
Further, reference numeral 4 indicates an optical head section for irradiating a laser light LB on the perpendicular magnetization layer 3. In the present example, the optical head section 4 is provided with a semiconductor laser element 5 and a lens 6 and this optical head section 4 is arranged to be movable along the radial direction of the magneto-optical disk 1 maintaining a predetermined distance from the surface of the magneto-optical disk 1. In this case, the optical head section 4 is operative to locally irradiate the perpendicular magnetization layer 3 of the magneto-optical disk 1 with the laser light LB with a constant intensity continuously emitted from the semiconductor laser element 5 through the lens 6 so as to elevate the temperature on the irradiated part of the perpendicular magnetization layer 3 above the Curie point.
Reference numeral 7 designates an electromagnet for applying a magnetic field to he perpendicular magnetized film 3 of the magneto-optical disk 1. In the present example, the electromagnet 7 is placed facing the optical head section 4 with the magneto-optical disk 1 interposed therebetween, and the electromagnet 7 is arranged to be movable along the radial direction of the magneto-optical disk 1, associated with the optical head section 4.
Further in the present example, a magnetic field modulating circuit 8 is provided, the input side of this magnetic field modulating circuit 8 is connected with a recording signal input terminal 9 and the output side of this magnetic field modulating circuit 8 is connected with a coil 7A of the electromagnet 7. By the magnetic field modulating circuit 8, a current, the phase of which is inverted in response to recording signal supplied thereto through the record signal input terminal 9, for example, a current flowing in the direction of an arrow A is supplied to the coil 7A when the signal level of a recording signal is at a high level "1", and a current flowing in the direction of an arrow B is supplied to the coil 7A when the signal level of a record signal is at a low level "0", whereby the electromagnet 7 generates a magnetic field as indicated by an arrow X when the signal level of the recording signal is at the high level "1", and a magnetic field as indicated by an arrow Y when the signal level of the recording signal is at the low level "0". In this case, the magnetic field indicated by the arrow X and the magnetic field indicated by the arrow Y are directed opposite to each other, however, the intensities thereof are made equal to each other. If the intensities of the magnetic field indicated by the arrow X and the magnetic field indicated by the arrow Y are designated Hc and -Hc, respectively, in consideration of their directions, .vertline..+-.Hc.vertline. are respectively determined to be such an intensity that the magnetizing direction of the perpendicular magnetization layer 3 of the magneto-optical disk 1 can be directed in the direction of the respective magnetic fields.
In the present example of the magneto-optical recording apparatus thus constructed, when a recording signal, for example, as shown in FIG. 2A, is supplied to the magnetic field modulating circuit 8, the electromagnet 7 produces a magnetic field as shown in FIG. 2B, and this magnetic field is to be applied to the perpendicular magnetization layer 3 of the magneto-optical disk 1. In
REFERENCES:
patent: 4712203 (1987-12-01), Saito et al.
Aoki Yoshio
Horimai Hideyoshi
Nguyen Hoa T.
Sony Corporation
Stephan Steven L.
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