JPH05166242A - Magneto-optical recorder - Google Patents

Abstract

PURPOSE:To contrive miniaturization and light weight of the magneto--optical recorder. CONSTITUTION:Magnetic circuits 3a, 3b and 3c are possessed by a driving source of a driving means 3 for driving and controlling an objective lens 1 in order to make a magneto-optical recording medium 5 irradiated with a light beam 2 in a prescribed position. Then, a leakage magnetic field H from the above magnetic circuits is impressed as a bias magnetic field upon the medium 5 instead of providing a dedicated bias magnetic field impressing means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bias magnetic field applying means used in a magneto-optical recording apparatus for recording or erasing information on a magneto-optical recording medium. A magneto-optical disk device using a disk-shaped magneto-optical recording medium will be described below.

[0002]

2. Description of the Related Art The recording layer of a magneto-optical disk is formed by a perpendicular magnetization film having an easy axis of magnetization in the direction perpendicular to the film surface. The magnetization direction of the perpendicular magnetization film is aligned in one direction by, for example, an external magnetic field before recording. The information recording operation is performed by irradiating the recording portion with a laser beam in a state where a bias magnetic field having a magnetic field opposite to the magnetization direction aligned in the one direction is applied. In this specification, a magnetic field applied to the medium for recording or erasing is referred to as a bias magnetic field.

There are two types of recording processes, the Curie point recording method and the compensation point recording method. In the Curie point recording method, the temperature of the recording portion is heated to the Curie point or higher by the irradiation of the laser beam to eliminate the coercive force of the perpendicularly magnetized film in the recording portion, and then the recording material is cooled to recover the magnetization. This is a method of reversing the magnetization direction by a bias magnetic field.
Further, by bringing the irradiation with the laser light close to the Curie point, the coercive force of the perpendicular magnetization film of the recording portion is lowered,
It is also possible to reverse the magnetization direction by the bias magnetic field.

The compensation point recording method uses a magneto-optical disk having a recording layer of a perpendicular magnetization film having a composition having a compensation temperature near room temperature. The compensation temperature is a temperature at which the magnetization sharply decreases and the coercive force becomes very large before reaching the Curie point. Then, the perpendicular magnetization film is heated by the laser light, and the magnetization direction is reversed by the applied bias magnetic field while the coercive force of the perpendicular magnetization film is lowered.

As described above, information is recorded on the magneto-optical disk by irradiating the laser beam according to the information to be recorded. Further, if the above-described recording operation is performed in a state where the direction of the bias magnetic field is opposite to that at the time of recording,
The recorded information can be erased. As a bias magnetic field applying means, for example, an electromagnet or a permanent magnet has been used.

As described above, in order to record or erase information on the magneto-optical disk, a bias magnetic field generator for generating a bias magnetic field is required. This bias magnetic field generator is arranged at a position facing an optical pickup that forms a spot of laser light on a magneto-optical disk so as to cover the movable range of the optical pickup with the disk sandwiched therebetween.

FIG. 5 is a schematic view showing a state where information is recorded (or erased) in the conventional magneto-optical disk device. The magneto-optical disk 5 is rotationally driven in a fixed direction by a driving means (not shown) (for example, a spindle motor). Bias magnetic field generator 10
Is composed of a permanent magnet and a yoke, and is installed so that its longitudinal direction covers the entire recording area of the disk 5 in the radial direction. The bias magnetic field generator 10 shown in FIG. 5 is set so that the magnetic field is always applied to the disk 5 in the direction indicated by arrow E.

This disk device is provided with a guide mechanism 11 and a positioner 8 provided along the radial direction of the disk 5. The positioner 8 is movable in the radial direction of the disk 5 along the guide mechanism 11. The positioner 8 has an optical pickup for irradiating the target track with the laser light 2. This optical pickup includes an objective lens 1 for emitting a laser beam 2, a lens support 6 for supporting the objective lens 1, a light source for the laser beam 2, an optical system (not shown) for guiding the laser beam to the objective lens 1, a laser. A focusing actuator 3 for keeping the focus of the light 2 always on the recording surface of the disk, and a tracking actuator 4 for keeping the focus at the center of the track are provided.

Then, after the positioner 8 is moved to the movable range of the optical pickup, the laser beam 2 is irradiated onto the target track by this optical pickup to perform recording or erasing. A voice coil motor is generally used as a drive source for moving the positioner 8. This voice coil motor includes a positioner driving coil 8a and a positioner driving magnet 8b as shown in FIG.
And a magnetic circuit including a positioner driving yoke 8c. Then, the positioner 8 is moved by passing a current through the coil 8a at an appropriate time.

Further, the focusing actuator 3
Controls the objective lens 1 in the F direction in the figure so that the focus of the laser light 2 is on the recording surface. This drive source is generally a voice coil, like the positioner 8.
A motor is used. This voice coil motor includes a focusing actuator coil 3 shown in FIG.
The magnetic circuit includes a, a focusing actuator magnet 3b, and a focusing actuator yoke 3c.

The tracking actuator 4 includes an objective lens 1 so that the laser beam 2 scans the track.
Is controlled (driven in the direction perpendicular to the paper surface in the figure). A voice coil motor is also generally used as the drive source. This voice coil motor is
The magnetic circuit comprises an actuator coil 4a, a tracking actuator magnet 4b, and a tracking actuator yoke 4c.

Control of focusing and tracking is generally performed by using a servo mechanism or the like. The magnetic shield 9 shields the leakage magnetic field so that the leakage magnetic field generated from the magnetic circuit of the focusing actuator 3, the tracking actuator 4 and the positioner 8 does not affect the recording portion of the disk to which the bias magnetic field is applied. To do.

[0013]

As described above, the conventional magneto-optical disk apparatus has the bias magnetic field generator for applying the bias magnetic field to the disk. But,
As described above, this magnetic field generator is installed so as to cover the entire area in the radial direction of the disk, and is a relatively large component as a disk device. Therefore, when aiming to reduce the size and weight of this disk device,
It was a hindrance.

Further, in order to prevent the leakage magnetic field generated from the magnetic circuit from affecting the bias magnetic field, it is necessary to consider the shielding of this leakage magnetic field. The present invention aims to solve the above problems.

[0015]

To achieve the above object, according to the present invention, an objective lens for converging a light beam and a spot of the light beam formed by the objective lens are positioned on a recording surface of a magneto-optical recording medium. And a tracking actuator for controlling the spot so that the spot is located on a predetermined track of the medium, and the focusing actuator and the tracking actuator are orthogonal to the track with respect to the medium. Positioner to move in the direction,
In at least one of the focusing actuator, the tracking actuator, and the positioner, the magneto-optical recording apparatus includes a driving unit having a magnetic circuit as a drive source for controlling or moving the focusing actuator, and a leakage magnetic field from the magnetic circuit is generated. A bias magnetic field was applied to the medium.

[0016]

In the present invention, the leakage magnetic field from the magnetic circuit included in the component parts provided in the magneto-optical recording device is applied to the medium as a bias magnetic field. Therefore, it is not necessary to provide a dedicated magnetic circuit (for example, the bias magnetic field applying device) for applying a bias magnetic field as in the conventional case. Therefore, the number of components of the magneto-optical recording device can be reduced, and the size and weight of the device can be reduced.

For example, when the tracking actuator and the focusing actuator described above are provided with a driving means having a magnetic circuit for driving the objective lens, the leakage magnetic field generated from this magnetic circuit may be used as the bias magnetic field. In general, the magnetic circuit of each actuator is arranged near the objective lens, so that the leakage magnetic field is always applied near the objective lens. On the other hand, the portion of the medium where recording or erasing is performed is irradiated with laser light through the objective lens. Therefore, the recording part or the erasing part of the medium is in a state where the leakage magnetic field is applied.

Further, since the positioner having the tracking actuator and the focusing actuator moves together with the objective lens, the leakage magnetic field from the magnetic circuit of the positioner is always applied near the objective lens. Therefore, the leakage magnetic field is applied to the recording portion or the erasing portion of the medium.

Thus, the leakage magnetic field from each magnetic circuit is always applied in the vicinity of the objective lens. As a result, when the medium is irradiated with laser light from the objective lens, the irradiated portion is magnetized in the direction of the leakage magnetic field, and information is recorded or erased. In this case, it is not necessary to provide the magnetic shield by removing the magnetic shield blocking the leakage magnetic field from each actuator and the positioner and setting the leakage magnetic field in this state to be applied to the medium.

The present invention will be described below with reference to examples.
The present invention is not limited to this.

[0021]

First Embodiment FIG. 1 is a schematic diagram showing a first embodiment of the present invention. In FIG. 1, constituent elements having the same configurations and functions as those in FIG. 5 are designated by the same reference numerals, and description thereof will be omitted. In this embodiment, the focusing actuator 3 is used.
The leakage magnetic field from the magnetic circuit of the voice coil motor, which is the driving source of the above, is used as the bias magnetic field. This magnetic circuit includes a focusing actuator coil 3a, a focusing actuator magnet 3b, and a focusing actuator yoke 3a.
The laser beam 2 is focused on the recording surface of the magneto-optical disk 5 by controlling the driving of the objective lens 1 in the F direction.

The arrangement of the focusing actuator magnet 3b is such that the disk 5 on which the laser beam 2 is irradiated is arranged.
The direction of the leakage magnetic field H in the irradiation part A is set to be the direction perpendicular to the disk 5 (indicated by arrow E in the figure). Therefore, the leakage magnetic field H from this magnetic circuit
Acts as a bias magnetic field on the irradiation portion A of the disk 5 irradiated with the laser light 2.

In the above structure, when the laser beam 2 is irradiated from the objective lens 1 onto the disk 5, the disk 5
The irradiation part A is heated and its coercive force is lower than the leakage magnetic field H. At this time, since the leakage magnetic field H is applied to the irradiation unit A, the irradiation unit A is magnetized in the same direction as the leakage magnetic field H, and information is recorded or erased.

[0024]

[Embodiment 2] FIG. 2 is a schematic sectional view showing a second embodiment of the present invention. 2, constituent elements having the same configurations and functions as those in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the leakage magnetic field from the magnetic circuit of the voice coil motor, which is the drive source of the positioner 8, is used as the bias magnetic field. This magnetic circuit is formed by a positioner driving coil 8a, a positioner driving magnet 8b, and a positioner driving yoke 8c.
Then, the positioner 8 on which the optical pickup 7 is installed is moved along the guide mechanism 11 in the radial direction of the disc 5 (perpendicular to the paper surface).

In this case, the positioner driving magnet 8b is arranged such that the direction of the leakage magnetic field H at the irradiation portion A of the magneto-optical disk 5 irradiated with the laser beam 2 is perpendicular to the disk 5 (indicated by an arrow in the figure). (Shown by E). Therefore, the leakage magnetic field H from this magnetic circuit acts as a bias magnetic field on the irradiation portion A of the disk 5 irradiated with the laser light 2.

[0026]

[Third Embodiment] FIG. 3 is a schematic sectional view showing a third embodiment of the present invention. 3, constituent elements having the same configurations and functions as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. In this embodiment, the leakage magnetic field from the magnetic circuit of the voice coil motor, which is the drive source of the tracking actuator 4, is used as the bias magnetic field. This magnetic circuit is formed of a tracking actuator coil 4a, a tracking actuator magnet 4b, and a tracking actuator yoke 4c. The laser beam 2 is controlled to a predetermined track by controlling the drive of the objective lens 1 in the T direction. I am trying to irradiate the top.

The arrangement of the tracking actuator magnet 4b is such that the disk 5 on which the laser beam 2 is irradiated is arranged.
The direction of the leakage magnetic field H in the irradiation part A is set to be the direction perpendicular to the disk 5 (indicated by arrow E in the figure). Therefore, the leakage magnetic field H from this magnetic circuit
Acts as a bias magnetic field on the irradiation portion A of the disk 5 irradiated with the laser light 2.

[0028]

[Fourth Embodiment] FIG. 4 is a schematic sectional view showing a fourth embodiment of the present invention. 4, constituent elements having the same configurations and functions as those in FIG. 5 are designated by the same reference numerals, and description thereof will be omitted. In this embodiment, the leakage magnetic field from the magnetic circuit of the voice coil motor, which is the driving source of each of the focusing actuator 3 and the tracking actuator 4, is used as the bias magnetic field.

The tracking actuator 4 has, as a drive source, a voice coil motor having a magnetic circuit formed of a tracking actuator coil 4a, a tracking actuator magnet 4b, and a tracking actuator yoke 4c. The objective lens 1 is driven and controlled in the direction perpendicular to the paper surface. Further, the focusing actuator 3 has a voice coil motor having a magnetic circuit formed by the focusing actuator coil 3a, the focusing actuator magnet 3b, and the focusing actuator yoke 3c as a driving source, and has an objective. The lens 1 is drive-controlled in the F direction.

Magnet 4b for tracking actuator
With the arrangement of the focusing actuator magnet 3b, the direction of the leakage magnetic field H at the irradiation portion A of the disk 5 irradiated with the laser light 2 is perpendicular to the disk 5 (indicated by arrow E in the figure). Is set. At this time, in order to prevent the leakage magnetic fields from interfering with each other to prevent proper bias magnetic fields from being formed, the arrangement of the magnets in each magnetic circuit is determined in consideration of this point. Therefore,
The leakage magnetic field H from each of these magnetic circuits acts as a bias magnetic field on the irradiation portion A of the disk 5 irradiated with the laser light 2.

As described above, according to the present invention, the bias magnetic field for recording (or erasing) can be applied to the medium without providing a dedicated magnetic circuit as the bias magnetic field generator. In addition, Embodiments 1 to 4
In the device described above, the magnetic shield mechanism is not provided so that the leakage magnetic field is applied to the disk as a bias magnetic field. Therefore, the number of components of the device can be reduced, and the size and weight can be further reduced.

In the present invention, the source of the leakage magnetic field used as the bias magnetic field is a magnetic circuit included in the driving means such as the focusing actuator, the tracking actuator and the positioner. Then, this magnetic circuit may be included in at least one of these driving means. Therefore, the other driving means may have a driving source other than the magnetic circuit (for example, a feed screw mechanism).

When the plurality of driving means have magnetic circuits, by combining the magnetic circuits as in the fourth embodiment, the leakage magnetic field from each magnetic circuit can be used as the bias magnetic field. The present invention is not limited to a magneto-optical disk device that uses a disk-shaped medium, and similar effects can be obtained even in an apparatus that uses a card-shaped medium, for example.

[0034]

As described above, according to the present invention, it is not necessary to provide a dedicated magnetic circuit as the bias magnetic field generating means in the magneto-optical recording device. Also, since it is not necessary to consider the shield of the leakage magnetic field generated from the magnetic circuit,
The shield mechanism is unnecessary. Therefore, the number of components of the device can be reduced, and the size and weight can be reduced.

There is also an advantage that the manufacturing cost of the device can be kept low.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a second embodiment of the present invention.

FIG. 3 is a schematic sectional view showing a third embodiment of the present invention.

FIG. 4 is a schematic sectional view showing a fourth embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view showing a state in which a bias magnetic field is applied in a conventional magneto-optical disk device.

[Explanation of symbols for main parts]

 1 Objective Lens 2 Laser Light 3 Focusing Actuator 3a Focusing Actuator Coil 3b Focusing Actuator Magnet 3c Focusing Actuator Yoke 4 Tracking Actuator 4a Tracking Actuator Coil 4b Tracking Actuator Magnet 4c Tracking Actuator Yoke 5 Magneto-optical disk (magneto-optical recording medium) 6 Lens support 7 Optical pickup 8 Positioner 8a Positioner drive coil 8b Positioner drive magnet 8c Positioner drive yoke 9 Magnetic shield 10 Bias magnetic field generator 11 Guide mechanism

Claims (1)

[Claims] 1. An objective lens for converging a light beam, a focusing actuator for controlling a spot of the light beam formed by the objective lens so as to be positioned on a recording surface of a magneto-optical recording medium, and the spot is a medium. In a magneto-optical recording device comprising: a tracking actuator for controlling the tracking actuator to be positioned on a predetermined track; and a positioner for moving the focusing actuator and the tracking actuator with respect to the medium in a direction orthogonal to the track. , The focusing actuator, tracking
At least one of the actuator and the positioner,
A magneto-optical recording apparatus, characterized in that a drive source is provided with a drive means including a magnetic circuit as a means for controlling or moving the magnetic field, and a leakage magnetic field from the magnetic circuit becomes a bias magnetic field applied to the medium.