JPH1116108A - Magneto-optical disk drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with two magneto-optical disks having their different substrates in thickness in simple constitution. SOLUTION: A center yoke 15 of a bias magnetic field generating device is so constituted that its end part facing a magneto-optical disk is branched into 1st and 2nd center yoke parts 15a and 15b. The 1st center yoke part 15a is for giving a proper magnetic field to a recording surface a1 of a magneto- optical disk (a) to be irradiated with a laser beam from an objective lens 1a, and the 2nd center yoke part 15b is for giving a proper magnetic field to a recording surface b1 of magneto-optical disk (b) to be irradiated with a laser beam from an objective lens 1b. Positions of the 1st center yoke part 15a and the 2nd center yoke part 15b are different from each other in the vertical direction to these magneto-optical disk surfaces respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magneto-optical disk drive capable of recording or erasing information on two magneto-optical disks having different substrate thicknesses.

[0002]

2. Description of the Related Art A magneto-optical disk drive device used for a computer memory, a document file, or the like performs recording and reproduction of information by exchanging a cartridge containing a magneto-optical disk. In this magneto-optical disk drive, the direction of an externally applied auxiliary magnetic field (bias magnetic field) is used for recording and erasing information by utilizing the property that the temperature of the recording medium rises due to laser beam irradiation and the coercive force decreases. To switch between recording and erasing. That is, a magneto-optical disk (hereinafter, referred to as a disk) used in a magneto-optical disk drive device has a magnetic film formed on a recording surface thereof and is magnetized in one direction in a direction perpendicular to the recording surface in advance. When the disk is irradiated with laser light while applying a magnetic field in the opposite direction, the direction of magnetization is reversed. Information is recorded by reversing the direction of magnetization according to the information.
Further, by irradiating a laser beam while applying a magnetic field in a further opposite direction (that is, a direction previously magnetized), recorded information can be erased. To reproduce the recorded information, the disk is irradiated with laser light. The plane of polarization of the reflected light from the magnetized disk is rotated by the Kerr effect. Since the Kerr effect changes the direction of rotation by reversing the magnetization direction of the disk, information can be reproduced by detecting the direction of rotation. The outline of the magneto-optical disk drive will be described with reference to the drawings. The magneto-optical disk drive 50 shown in FIG. 8 includes a disk rotating table 54 rotated by a spindle motor 53, an optical head 55, a bias magnetic field applying device 56, It incorporates a loading mechanism 57. When the cartridge 52 containing the disk 51 is inserted into the magneto-optical disk drive 50, as shown in FIG. 9, the cartridge 52 is set on the disk turntable 54 by the loading mechanism 57, and the bias magnetic field evacuated upward is generated. The device 56 is lowered, and moves to a position facing the optical head 55 with the disk 51 interposed therebetween. Then, a magnetic field is applied by the bias magnetic field generator 56 while rotating the disk 51, and the optical head 55 irradiates a laser beam while moving in the direction A to record and erase information on the disk 51.
When reproducing information, laser light may be applied without applying a magnetic field.

In such a magneto-optical disk drive device, Japanese Patent Application Laid-Open No. 6-1316 discloses an example of a bias magnetic field generator for generating a magnetic field necessary for recording or erasing information.
No. 08 is described with reference to FIGS. One bent portion of each of the U-shaped sheet metal members 60 and 70
A pair of positioning projections 62 and 72 (72 is not shown) and recesses 63 and 73 are provided in pairs 61 and 71, and a projection 62 and a recess 73 are provided.
The center yoke 80 is formed by fitting the convex portion 72 and the concave portion 63 such that the bent portions 61 and 71 are adjacent to each other, and the other bent portions 64 and 74 form side yokes. A hole 91 is formed at the center of the insulating sheet 90 so that the center yoke 80 can be inserted.
The bias magnetic field generating device 56 is formed by inserting both of them into the center yoke 80 and fixing them by bonding.

[0004]

In recent years, there has been a strong demand for further increasing the recording density of information, and one measure to meet the demand is to reduce the thickness of the disk substrate.

In order to increase the recording density, it is necessary to reduce the spot diameter r of the laser light applied to the disk. The spot diameter r is given by the following equation with respect to the numerical aperture NA of the objective lens and the wavelength λ of the laser light. The relationship is as follows.

R∝λ / NA (1) The above equation (1) shows that an objective lens having a large NA can reduce the spot diameter r and enable high-density recording. When (1) is used, spot aberration due to disc tilt (tilt) or the like increases. To suppress this, it is effective to reduce the thickness of the disk substrate. Therefore, in order to enable high-density recording, it is preferable that the disk substrate be thinner than a conventional disk.

At present, a disk having a thickness of 1.2 mm is used as a disk. However, as described above, in order to cope with high-density recording, a thinner substrate thickness (for example, 0.6 mm) is used. ) Is likely to appear,
In the near future, it is expected that thick (1.2 mm) and thin (0.6 mm) disk substrates will coexist.

When such a situation occurs, the following problems occur. The bias magnetic field generator in the current optical disk drive device determines the mounting position (particularly the position that determines the distance from the disk) and the shape so that an appropriate magnetic field is applied to the recording surface of the disk with a substrate thickness of 1.2 mm. Have been. When a disk having a substrate thickness of 0.6 mm is inserted into an optical disk drive device provided with such a bias magnetic field generator, the distance between the bias magnetic field generator and the recording surface of the disk is one. .2
As compared with a disk having a thickness of mm, the distance is increased by 0.6 mm, and an appropriate magnetic field cannot be given. In order to apply an appropriate magnetic field even to a disk with a thickness of 0.6 mm, apply a larger current to the winding coil, increase the number of turns of the winding coil, or move the bias magnetic field generator vertically to the disk. Various measures such as providing a mechanism for moving are required, but there are disadvantages such as an increase in power consumption, an increase in the size of the bias magnetic field generator, and an increase in the size of the magneto-optical disk drive. None of them are satisfactory.

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problem, and to provide a magneto-optical disk drive capable of coping with magneto-optical disks having different substrate thicknesses, suppressing an increase in power consumption, and further reducing the size. It is.

[0010]

In order to achieve the above-mentioned object, the present invention provides a magneto-optical disk a having a first substrate thickness, a first laser beam, and a magneto-optical disk a having a first substrate thickness. An optical head for irradiating a second laser beam to the magneto-optical disk b having a second substrate thickness different from that of the second substrate, and the optical head extends in the radial direction of the magneto-optical disk on the opposite side with the magneto-optical disk interposed therebetween. In a magneto-optical disk drive device having a bias magnetic field generator including a center yoke, a winding coil, and a side yoke, the center yoke of the bias magnetic field generator has an end facing the magneto-optical disk. The first magnetic field generator is divided into a first magnetic field generator and a second magnetic field generator, and the first magnetic field generator applies an appropriate magnetic field to the recording surface of the magneto-optical disk irradiated with the first laser light. give The second magnetic field generating section applies an appropriate magnetic field to a recording surface of a magneto-optical disk irradiated with the second laser light, and the first magnetic field generating section and the second magnetic field The position with the generating section is different from each other in the direction perpendicular to the surface of the magneto-optical disk.

According to such a configuration, without increasing the number of bias magnetic field generators according to the magneto-optical disk,
Also, without moving the bias magnetic field generator,
One magneto-optical disk can be supported.

The first magnetic field generating section and the second magnetic field generating section have their lengths in the radial direction of the magneto-optical discs defined in accordance with the recordable area ranges of the magneto-optical discs a and b. This is desirable in order not to generate a magnetic field needlessly.

The distance between the first magnetic field generator and the magneto-optical disk a is d1, the distance between the second magnetic field generator and the magneto-optical disk b is d2, and the distance between the first magnetic field generator and the magneto-optical disk b is d1. Assuming that the distance between the adjacent side yoke is δ1 and the distance between the second magnetic field generator and the adjacent side yoke is δ2,
It is desirable that the bias magnetic field generator be configured so that d1 = d2 and δ1 = δ2 in order to apply the same magnetic field to the recording surface of each magneto-optical disk.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing a movable optical head of a magneto-optical disk drive device and a drive unit thereof, and FIG. 2 is an exploded perspective view of the movable optical head. In the figure, the X direction is the radial direction of the disk (+ X side is the inner peripheral side of the disk, the -X side is the outer peripheral side of the disk), the Y direction is the tangential direction of the information tracks of the disk, and the Z direction is the focusing direction.

This movable optical head is a member corresponding to the optical head 55 shown in FIG. 8, and is an optical head which can support disks having two kinds of substrate thicknesses. The objective lenses 1a and 1b are fixed to the holder 2 together with the focus coils 3a and 3b, and the objective lens 1a is a lens corresponding to, for example, a disk having a substrate thickness of 1.2 mm (hereinafter, disk a). The objective lens forms a spot on the recording surface a1.
1b is a lens corresponding to a disk (disk b) having a substrate thickness of, for example, 0.6 mm, which forms a spot on the recording surface b1 of the disk b.

Each end of a pair of leaf springs 4a and 4b is bonded to the holder 2. The other ends of the leaf springs 4a, 4b are bonded to the spring receiver 5, respectively. Thus, the holder 2 is supported by the spring receiver 5 and the leaf springs 4a and 4b so as to be movable in the Z direction (perpendicular to the recording medium).

The spring receiver 5 is adhesively fixed to a carriage 6, as shown in FIG. A pair of reflection mirrors 8a and 8b are adhesively fixed to the carriage 6. Reflection mirror 8a
Is for reflecting laser light to the objective lens 1a, and the reflecting mirror 8b is for reflecting laser light to the objective lens 1b.

On both sides of the carriage 6, rectangular tracking coils 9a and 9b are adhered, and a pair of bearing holes 7a and 7b are formed in the vicinity thereof along the X direction. The pair of bearing holes 7a, 7b have a pair of shafts 10a, 1
0b penetrates. Also, a pair of inner yokes 11a, 11b are inserted into the tracking coils 9a, 9b. Copper short rings 12a and 12b having a thickness of about 0.2 mm are attached to the outer periphery of the inner yokes 11a and 11b.
Outer yokes 13a, 13b are provided above the inner yokes 11a, 11b, respectively.
Are disposed, and the inner yokes 11a, 11b at the outer yokes 13a, 13b.
A pair of magnets 14a and 14b is fixed at a position facing.

The shafts 10a and 10b and the inner yokes 11a and 11b are fixed to a deck base (not shown). Outer yokes 13a, 13b
Is fixed to the deck base via the inner yokes 11a and 11b. The optical head thus configured is configured such that the drive current is applied to the tracking coils 9a and 9b, thereby causing the axes 10a and 10b to move.
Along the disk radial direction.

FIG. 3 shows a bias magnetic field generator.
This will be described with reference to FIGS. FIG. 3 is a sectional view of the bias magnetic field generator of the present embodiment. This bias magnetic field generator corresponds to the bias magnetic field generator 56 of FIG. FIG. 4 is a perspective view of the bias magnetic field generator, and FIG.
Is an exploded perspective view thereof.

The most characteristic part of the bias magnetic field generator according to the present embodiment is that the tip of the center yoke 15 is divided into a first center yoke 15a and a second center yoke 15b.
The second center yoke 15b is 0.6 mm thicker than the first center yoke 15a (disk a).
(Difference between the substrate thickness of the disk b and the disk b).

Hereinafter, the configuration will be described in detail. The yoke of the bias magnetic field generator includes a center yoke 15 and side yokes 16. The center yoke 15 is formed of a single elongated T-shaped plate-like member. A coupling portion 15c for coupling with the side yoke 16 is formed at one end, and the first center yoke portion 15a and the second Center yoke portion 15b. The first center yoke 15a is a yoke for applying an appropriate magnetic field to the disk a, and the second center yoke 15b is a yoke for applying an appropriate magnetic field to the disk b. The lower end surfaces of the center yokes 15a and 15b are used to correct the difference in substrate thickness between the disks a and b, that is, the distance d1 between the recording surface of each disk and the lower end surface of each center yoke. To make d1 = d2 for d2,
The second center yoke 15b is not formed on the same plane.
Is formed so as to protrude toward the movable head by 0.6 mm as compared with the first center yoke 15a. Also,
The concave portion at the boundary between the first center yoke 15a and the second center yoke 15b reduces the magnetic flux in each magnetic gap between each center yoke and each side yoke, and reduces the magnetic field perpendicular to the disk surface. Is to give.

The side yoke 16 is formed by punching and bending a single plate-like member. By punching out substantially the center of the plate-like member, a cut-out portion 16c that fits with the coupling portion 15c of the center yoke 15 is formed. The first and second side yokes are bent by bending both sides of the cutout portion 16c in a U-shape.
16a and 16b are formed.

To mount the winding coil 17 on the yoke thus formed and assemble the bias magnetic field generator, first, the hollow portion of the winding coil 17 is inserted into the center yoke 15 and the side yoke 16 Of the notch 16c (from the near side in FIG. 5). that time,
The coupling part 15c of the center yoke 15 is inserted into the notch part 16c of the side yoke 16 while being fitted thereto, and is adhesively fixed. Each center yoke when the center yoke 15 is assembled
Regarding the distances (magnetic gaps) δ1 and δ2 between the side yokes 15a and 15b and the adjacent side yokes 16a and 16b, the dimensions of the center yoke 15 and the side yokes 16 are determined so that δ1 = δ2.

This bias magnetic field generating device has a center yoke 15 and a center yoke 16 extending in the radial direction of the disk on the opposite side of the movable optical head with respect to the disk inserted into the drive device. The center yoke 15a is arranged on the optical axis of the objective lens 1a, and the second center yoke 15b is arranged on the optical axis of the objective lens 1b.

The recording of information in the magneto-optical disk drive configured as described above will be described below.
First, when the disc a is inserted into the drive device, the drive device is recognized by the known disc discriminating means that the disc a is inserted, and the objective lens 1a is selected.

When a recording operation command is issued, the objective lens
A recording laser beam is emitted from 1a and focused on the recording surface a1 of the disk a to form a spot. When a predetermined current is applied to the winding coil of the bias magnetic field generator, a magnetic field is generated from each of the two center yokes, but a magnetic field from the first center yoke 15a is applied to the spot via a distance d1. Given. Thus, information is recorded on the disc a.

Next, when the disk b is inserted into the drive device, the objective lens 1b is selected, and when a recording operation is instructed, the recording laser beam emitted from the objective lens 1b causes the recording surface of the disk b to be recorded. The second center yoke of the bias magnetic field generator is provided on the spot formed on b1.
The magnetic field generated from 15b is provided. Note that the recording surface b1 of the disc b extends from the lower end surface of the second center yoke 15b.
The distance to is d2. Thus, information is recorded on the disc b.

Here, (1) the substrate thickness of the disk a is 1.
2 mm, the substrate thickness of the disk b is 0.6 mm, (2) second
The center yoke 15b has a protrusion amount of 0.6 mm, and (3) the distance d1 = d2 from each center yoke to each recording surface, the magnetic field strength at the spot of the disk a and the magnetic field at the spot of the disk b Are almost the same.

As described above, according to the present embodiment, for the two disks having different substrate thicknesses, two center yokes for correcting the difference in the disk substrate thickness are provided in the bias magnetic field generator. A magnetic field of the same strength can be applied to the recording surface of each disk. Also, without changing the number of turns of the winding coil, without changing the amount of current flowing through the winding coil, and without providing a moving mechanism that moves the bias magnetic field generator up and down according to the substrate thickness of the disk, Since the same magnetic field can be applied to the recording of each disk, the size of the bias magnetic field generator is increased, and the entire drive device is not enlarged.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, a disc a having a recording area in the range of la with a substrate thickness of 1.2 mm,
a first center yoke 15a and a side yoke 16a corresponding to the disk a, and a second center yoke 15b and a side yoke corresponding to the disk b. Each of the 16b has a different radial length.

The other configuration is the same as that of the first embodiment, and the description is omitted. With this configuration, the lengths of the center yokes 15a and 15b and the side yokes 16a and 16b are appropriately determined so that a magnetic field is applied only to an area of the disk where recording (including erasure is necessary). In addition, unnecessary magnetic fields can be omitted, and a decrease in the magnetic field strength can be suppressed.

In the present embodiment, the radial length of each center yoke and each side yoke is specified according to the range of different recording areas. However, the present embodiment can be applied to a case where the starting points of the recording areas are different. In other words, when the disk a starts at 25 mm from the center of the disk and the disk b starts at 23 mm from the center of the disk, the center yoke 15a corresponding to the disk a becomes the center yoke corresponding to the disk b. What is necessary is just to form it by 2 mm shorter than the yoke 15b.

Next, a third embodiment of the present invention will be described with reference to FIG. In the bias magnetic field generator of the present embodiment,
The center yoke 15 is joined to the plate member on which the first center yoke portion 15a is formed and the plate member on which the second center yoke portion 15b is formed by using a non-magnetic material-based adhesive (for example, an epoxy-based adhesive). It is configured by joining.

The other structure is the same as that of the first embodiment, and will not be described. According to this configuration, compared to the first embodiment in which the first and second center yoke portions 15a and 15b are formed from a single plate-like member to manufacture the center yoke 15, the manufacture of the center yoke 15 is improved. It will be easier.

[0036]

As described above, according to the magneto-optical disk drive of the present invention, it is possible to cope with magneto-optical disks having different substrate thicknesses, to suppress an increase in the power consumption of the bias magnetic field generator, and to reduce the size of the device. Can also be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a movable head and a driving unit thereof according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the movable head of FIG.

FIG. 3 is a sectional view of a bias magnetic field generator according to the first embodiment of the present invention.

FIG. 4 is a perspective view of the bias magnetic field generator of FIG.

FIG. 5 is an exploded perspective view of the bias magnetic field generator of FIG.

FIG. 6 is an exploded perspective view of a bias magnetic field generator according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a bias magnetic field generator according to a third embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view of a conventional magneto-optical disk drive device, showing a state before a magneto-optical disk is inserted.

FIG. 9 is a schematic cross-sectional view of a conventional magneto-optical disk drive device, showing a state at the time of completion of insertion of a magneto-optical disk.

FIG. 10 is an exploded perspective view of a conventional bias coil magnetic field generator.

11 is a sectional view of the bias coil magnetic field generator of FIG.

FIG. 12 is a perspective view of a U-shaped sheet metal member constituting the bias coil magnetic field generator of FIG.

[Explanation of symbols]

 1a, 1b Objective lens 3a, 3b Focus coil 4a, 4b Leaf spring 5 Spring receiver 6 Carriage 8a, 8b Reflection mirror 9a, 9b Tracking coil 10a, 10b Axis 11a, 11b Inner yoke 13a, 13b Outer yoke 14a, 14b Magnet 15 Center Yoke 15a First center yoke 15b Second center yoke 15c Coupling part 16 Side yoke 16a First side yoke 16b Second side yoke 16c Notch 17 Winding coil

Claims (3)

[Claims] 1. A first magneto-optical disk a having a first substrate thickness has a first substrate thickness.
An optical head for irradiating a second laser beam to a magneto-optical disk b having a second substrate thickness different from that of the magneto-optical disk a, and the magneto-optical disk A magneto-optical disk drive device having a bias magnetic field generator including a center yoke, a winding coil, and a side yoke disposed to extend in the radial direction of the magneto-optical disk on the opposite side of the bias magnetic field generator, The center yoke has an end facing the magneto-optical disk and a first magnetic field generating portion.
The first magnetic field generating section applies an appropriate magnetic field to a recording surface of a magneto-optical disk irradiated with the first laser light, and the second magnetic field generating section The magnetic field generating unit is for applying an appropriate magnetic field to the recording surface of the magneto-optical disk to which the second laser light is irradiated. The position of the first magnetic field generating unit and the position of the second magnetic field generating unit are
A magneto-optical disk drive device characterized in that the magneto-optical disk drive device is configured to be different from each other in the direction perpendicular to the magneto-optical disk surface. 2. The magneto-optical disk drive according to claim 1, wherein the first magnetic field generator and the second magnetic field generator are arranged in accordance with the recordable area of each of the magneto-optical disks a and b. A magneto-optical disk drive device wherein the length in the radial direction of the magneto-optical disk is defined. 3. The magneto-optical disk drive according to claim 1, wherein a distance between the first magnetic field generating section and the magneto-optical disk a is d.
1. The distance between the second magnetic field generator and the magneto-optical disk b is d
2. Assuming that the distance between the first magnetic field generating section and the adjacent side yoke is δ1, and the distance between the second magnetic field generating section and the adjacent side yoke is δ2, d1 = d2 and δ1 = A magneto-optical disk drive device comprising a bias magnetic field generator configured to satisfy δ2.