JPH03225648A - Magneto-optical disk device - Google Patents

Abstract

PURPOSE:To record/reproduce/erase information at a high speed with high accuracy by adjacently or closely arranging the side surfaces of two magnets to each other, whose magnetization directions are vertical to the surface of a magneto-optical film along an anisotropic axis direction and are opposite to each other. CONSTITUTION:A bias magnet 4 is constituted of the prism-like magnets 5A and 5B whose magnetization directions are opposite to each other and an iron yoke 6. The magnets 5A and 5B are stuck to the lower surface of the yoke 6 in a state where their inner side surfaces are adjacent to each other to be stuck, and positioned above light spots 13a and 13b respectively. In the magneto- optical film 2b below the magnets 5A and 5B, bias magnetic field whose pitch is small is formed to be in the vertical direction to the surface of the film 2b and in the opposite direction to each other. Thus, the spots 13a, 13b and 13c are respectively used for erasion, recording and reproducing, thereby accomplishing the high-speed and high-accuracy recording/reproducing/erasion.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magneto-optical disk device capable of recording/reproducing/erasing information at high speed and high density.

(Prior Art) In recent years, magneto-optical disk devices for recording/reproducing/erasing information on magneto-optical disks have been used for recording computer data, document files, etc. In this magneto-optical disk device, in order to enable overwriting, which is possible with magnetic recording, a method has been proposed in which an erasing operation is simultaneously performed prior to the recording operation.

FIG. 2 is a schematic configuration diagram showing an example of a conventional magneto-optical disk device.

As shown in the figure, the conventional magneto-optical disk device 21 is
It is composed of a magneto-optical disk 2, a bias magnetic field applying device 23, a laser recording/reproducing device 28, and the like.

This magneto-optical disk 2 uses Fe, Co5Tb5G, etc. to record and reproduce information using the magneto-optic effect on the upper surface of the substrate 2a, which is a disk made of transparent resin such as polycarbonate.
A first magnetic film (MoJ) 2b made of d, etc. is formed, and a protective film 2c made of ultraviolet curing resin etc. is further formed thereon.
is formed, and the information recording/recording of this magneto-optical film 2b
In the recording area where reproduction/erasure is performed, a large number of recording tracks are formed spirally or concentrically at a pitch of 1.6 μm. This disk 2 is rotationally driven at a predetermined speed by a spindle motor (not shown), and
A bias magnetic field in the perpendicular direction is applied to the magneto-optical film 2b by the bias magnetic field applying device 23 arranged on the protective film 2c side with a gap in between. Further, information is recorded/reproduced/erased by a laser beam from the laser recording/reproducing device 28 disposed on the magneto-optical film 2b from the substrate 2a side through a gap.

This laser recording/reproducing device 28 includes three laser diodes 9a, 9b, 9c whose output can be controlled independently.
Two semiconductor laser diodes formed on one chip,
It is composed of a collimating lens 10°, a polarizing beam splitter 11, an objective lens 12, an objective lens actuator 14, a detector 15, and the like. This laser diode 9a
.

The laser beams emitted from 9b and 9c pass through a collimating lens 10, a polarizing beam splitter 11, and an objective lens 12, respectively, onto the recording track on the magneto-optical film 2b of the disk 2 at a predetermined interval. It is irradiated as three small diameter light spots 33a, 33b, and 33c. That is, the light spots 33a, 33b, 33c
correspond to the outputs of laser diodes 9a, 9b, and 9c, respectively.

The bias magnetic field applying device 23 includes a bias magnet actuator 7, a prismatic magnet 25 magnetized in the longitudinal direction (the direction of magnetization is shown by an arrow), and a prismatic iron yoke 26A.

26B, and the like. The bias magnets 24 are fixed to the upper ends of the inner surfaces of the yokes 2BA and 26B on both end faces of the magnet 25, respectively, and are formed in a U-shape. , are arranged so as to be parallel to the upper surface of the protective film 2c of the disk 2 and above the light spots 33a and 33b, respectively. This yoke 26A and 2
In the magneto-optical film 2b below the magneto-optical film 6B, bias magnetic fields (the magnetic field directions are indicated by arrows) are formed in a direction perpendicular to the surface of the film 2b and in mutually opposite directions.

Next, the disk 2 is rotated in the direction shown by the arrow to erase the light spot 33a and the light spot 33b.
The operation of a conventional example in which the light spot 33c is used for recording and the light spot 33c is used for reproduction will be described.

These light spots 33a, 33b, and 33c have light intensities suitable for erasing, recording, and reproducing operations, respectively, when the disk device 21 is operating in the recording mode, and when the disk device 21 is operating in the reproducing mode. If so, the laser diodes 9a, 9b are suitable for reproducing operation.

It is controlled by an output control device 9C (not shown).

In this recording mode, the magneto-optical 1 on the recording track
The perpendicular magnetization direction of the yoke 2b is heated on the cue spot by the irradiation of the light spot 33a, so that it is aligned with the direction of the bias magnetic field below the yoke 26A, and an erasing operation is first performed. When this erased portion reaches the irradiation point of the light spot 33b due to the rotation of the disk 2,
The perpendicular magnetization direction of the magneto-optical film 2b on the recording track is determined by the irradiation of the optical spot 33b based on the recording signal, which is a digital signal corresponding to the recording button.
Only the irradiated portion is reversed by the bias magnetic field below the yoke 26B, thereby recording this recording signal.

Next, when this recorded portion reaches the irradiation point of the light spot 33C, a playback signal is obtained from the light reflected by the light spot 33c, and a controller (not shown) compares this playback signal with the record signal. . That is, the light spot 33c reflected on the surface of the magneto-optical H2b
Due to the magneto-optic effect, the direction of rotation of the polarization plane of the reflected light differs depending on the perpendicular magnetization direction of the magneto-optical film 2b, and the reflected light is transmitted to the detector 15 via the objective lens 12 and the polarizing beam splitter 11. In this detector 15, a reproduction signal is obtained from the difference in the rotation direction of the polarization plane, and a focus error and a tracking error are detected, and a focus servo signal and a tracking servo signal are generated.

Based on this focus servo signal, the focus servo operation is performed by controlling the vertical position of the objective lens 12 by the objective lens actuator 14. Also, based on the tracking servo signal, the tracking servo operation changes the radial position of the objective lens 12 (in the direction perpendicular to the plane of the drawing) by the actuator 1.
4. Also, based on the focus servo signal, the bias magnet 2
The constant interval servo operation for keeping the distance between the bias magnet 24 and the upper surface of the disk 2 at a predetermined constant value is performed by controlling the vertical position of the bias magnet 24 by the bias magnet actuator tough.

The feed operation for searching for the desired recording track is performed by integrally using the bias magnetic field applying device 23 and the laser recording/reproducing device 28 to move the recording area of the disk 2 from the outer diameter to the inner diameter by a feed device (not shown). This is done by moving it to a desired position within the range up to (in the figure, in a direction perpendicular to the plane of the paper).

As explained above, in the disk device 21, in the recording mode, a series of operations of erasing, recording, and reproduction (verification) are performed simultaneously.

In the case of the reproduction mode, the output of the laser diodes 9a and 9b is stopped, and the reproduction operation is performed as described above using the light spot 33c from the laser diode 9c.

(Problems to be Solved by the Invention) In the conventional compact magneto-optical disk device 21 having the above-described configuration, the bias magnet 24 is configured to control the pitch of the yokes 26A and 26B, and thus the bias magnetic fields in opposite directions. The problem was that the pitch was too wide. The fact that the pitch of the two bias magnetic fields in mutually opposite directions is wide, that is, the pitch of the optical spots 3' 3a and 33b is wide, increases the timing difference between the above-mentioned erasing operation and recording operation. This becomes an obstacle when trying to speed up the operation. Furthermore, due to the difference in curvature between the outer and inner peripheries of the recording track, the on-track accuracy of the light spots 33a and 33b decreases, which becomes an obstacle when attempting to improve the precision of the operation.

The present invention has been made with attention to the above points, and uses bias magnets capable of narrowing the pitch of the bias magnetic fields in opposite directions.
The object of the present invention is to provide a magneto-optical disk device that is capable of recording/reproducing/erasing information with high precision.

(Means for Solving the Problems) A magneto-optical disk device of the present invention includes a magneto-optical disk made of a magneto-optical film on which recording tracks are formed in a spiral or concentric form, and at least two types for erasing and recording. a laser recording/reproducing device that irradiates the recording track with two light spots at predetermined intervals from one side of the disk; In a magneto-optical disk device, the magneto-optical disk device includes a bias magnet that applies a bias magnetic field in the direction from the other surface of the disk, wherein the magnetization directions are perpendicular to the magneto-optical film surface along the anisotropy axis direction and in mutually opposite directions. is 2
The magnet is configured to include bias magnets in which side surfaces of two magnets are arranged adjacent to or close to each other.

(Embodiment) The magneto-optical disk device of the present invention is the magneto-optical disk device of the above-described type capable of overwriting, in which the magnetization direction is perpendicular to the magneto-optical film surface along the anisotropy axis direction. The above-mentioned object is achieved by providing a bias magnet in which the side surfaces of two magnets, which are opposite to each other in direction, are arranged adjacent to or close to each other.

FIG. 1 is a schematic configuration diagram showing an embodiment of a magneto-optical disk device of the present invention.

As shown in the figure, a magneto-optical disk device 1 according to an embodiment of the present invention includes a magneto-optical disk 2, a bias magnet 4,
It is comprised of a bias magnetic field applying device 3 consisting of a front bias magnet actuator 7, etc., a laser recording/reproducing device 8, etc., and is similar to the disk device 21 of the conventional example described above.
In contrast, as described above, only the pitches of the three optical spots, which correspond to the bias magnet 4 and the pitch of the bias magnetic fields in mutually opposite directions produced by the bias magnet 4, are different. Descriptions of parts similar to those in the example will be omitted.

Light spots 13a, 13 corresponding to the laser diodes 9a, 9b, 9c by this laser recording/reproducing device 8
b, 13c are the light spots 33 in the conventional example described above.
By narrowing the pitch of the laser diodes 9a, 9b, and 9c arranged in the cliff conductor diode 9, only the pitch is set narrower than that of the laser diodes 9a, 33b, and 33c.

The bias magnet 4 is composed of prismatic magnets 5A and 5B whose magnetizing directions are opposite to each other in the longitudinal direction (the magnetization directions are indicated by arrows), and a prismatic iron yoke 6. ing.

These magnets 5A and 5B each have a width dimension (circumferential dimension of the disk 2) of 0.3+n+s and a depth dimension (
The disk 2 has a prismatic shape with a diameter of 0.3 m+a and a height of 2 mm, and is made of a samarium-cobalt rare earth magnet with an energy product of 18 megagauss oersted, and is anisotropic in the longitudinal direction. It has an axial direction. As mentioned above, these magnets 5A and 5B are
They are magnetized in opposite directions along the anisotropy axis, their inner surfaces are glued together, and their upper end surfaces are
The yoke 6 is bonded to the lower surface of the yoke 6 for forming a magnetic path, and the lower end surfaces thereof are arranged to face the upper surface of the disk 2 with a gap distance of 0.2 mm, and the optical spots 13a and 13b It is configured to be located above each of the above. The magneto-optical film 2b below the magnets 5A and 5B is provided with a bias magnetic field (the direction of the magnetic field is indicated by an arrow) with a magnetic field strength of 100 Oe or more, which is perpendicular to the plane of the film 2B and far away from each other. )
or formed respectively. This magnetic field strength is a value that does not interfere with the above-described erasing and recording operations.

Then, using the light spot 13a for erasing, the light spot 13b for recording, and the light spot 13c for reproducing, erasing, recording, and reproducing operations are performed in the same manner as in the conventional case described above.

The magneto-optical disk device 1 according to an embodiment of the present invention having the above configuration is capable of the above-mentioned overwriting, and further includes:
Bias magnet 4 of the aforementioned bias magnetic field application device 3
By narrowing the pitch of the bias magnetic fields in opposite directions,
Since the pitch of the light spots 13a and 13b is narrowed, the timing difference between the erasing operation and the recording operation described above is smaller than that of the conventional disk device 21 described above, and the operation can be performed at high speed. It becomes possible. In addition, since the above-mentioned drop-off accuracy at the outer and inner peripheries of the recording track decreases or is small, the operation becomes high.
It becomes possible.

In the disk device 1 according to the embodiment of the present invention described above, the depth dimension of the magnets 5A and 5B of the bias magnet 4 is determined by the eccentricity of the recording track of the disk 2, manufacturing variations in each component, etc. Even if there is,
The above-described foot operation of the bias magnet 4 can be omitted by setting the depth so that it can sufficiently cover the recording area, or by configuring the depth to be larger than the width of the recording area. Also, these magnets 5A and 5B
Of course, a minute gap may be placed between the inner surfaces of the . In addition to the configuration described above, the λ bias magnet 4 may be of any type as long as it is lightweight and can form narrow pitch bias magnetic fields having the above-mentioned strengths and opposite directions. Further, in the recording mode, when the above-mentioned collation operation is not performed, the light spot 13C1, that is, the laser diode 9C can be omitted (in this case, the focus and tracking errors are detected using another light spot). This light spot 13c can also be used exclusively for this error detection.

Further, it goes without saying that the optical disc 2 may have a configuration other than the above-described configuration.

(Effects of the Invention) The magneto-optical disk device of the present invention having the above-described configuration is capable of overwriting and recording/reproducing/erasing information at high speed and with high precision, thus improving usability. , the functionality of the system using this disk device is improved.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a magneto-optical disk device of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of a conventional magneto-optical disk device. 1... magneto-optical disk device, 2... magneto-optical disk, 2b... magneto-optical film, 4...-
Bias magnet, 5A 5B... Magnet, 8... Laser recording/reproducing device, 13a, 13b, 13cm.--Light spot. M1 figure

Claims (1)

[Claims] A magneto-optical disk has a magneto-optical film on which a recording track is formed in a spiral or concentric form, and at least two optical spots, one for erasing and one for recording, are placed on the recording track at a predetermined interval. A laser recording and reproducing device that emits light from one side, and a bias magnet that applies bias magnetic fields in directions perpendicular to and opposite to each other from the other side of the disk in correspondence with the two light spots. In a magneto-optical disk device, a bias magnet is provided in which side surfaces of two magnets whose magnetization directions are perpendicular to the magneto-optical film surface along the anisotropy axis direction and in opposite directions are arranged adjacent to or close to each other. A magneto-optical disk device comprising: