Magneto-optical recording apparatus having an inversion signal d

Dynamic information storage or retrieval – Storage or retrieval by simultaneous application of diverse... – Magnetic field and light beam

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Details

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.

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