JP3640013B2 - Initialization method for phase change optical disc and initialization apparatus using the initialization method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a phase change optical disk initialization method and initialization apparatus, and more particularly to a phase change optical disk initialization method and initialization apparatus that can efficiently and quickly initialize a phase change optical disk.
[0002]
[Prior art]
In general, a phase change optical disk records information by irradiating a recording beam using a structural change between a non-crystallized state (amorphous state) and a crystalline state of a substance, and detects a difference in reflectance as a signal. As a recording material, chalcogen alloys such as GeSbte alloy and AglnSbTe alloy are generally used.
[0003]
A phase change optical disk is one in which a recording film is formed from these materials by vacuum deposition or sputtering. The recording film immediately after this formation is generally in a crystalline state or an amorphous state that is expected in an initial amorphous state. In addition, since the optical reflectance is several percent or less, it is known that the state cannot be recorded and reproduced as it is.
[0004]
For this reason, the phase change optical disk needs to be in an initial crystallized state (initialized) by heating and cooling the recording layer with a laser beam when first used.
[0005]
This initialization process is generally called an initialization process, and is performed by irradiating the recording layer of the phase change optical disc with laser light using an initialization device. Since it is necessary to irradiate light, the initialization is performed while moving an initialization beam having a predetermined recording width L having an oval shape in the disk radial direction in the disk radial direction.
[0006]
Incidentally, as a document describing the technology relating to the initialization of the above-described phase change optical disc, there are JP-A-5-159313 and JP-A-6-37400.
[Problems to be solved by the invention]
The recording width L of the initialization beam by the one light spot is generally about 200 μm. For this reason, for example, initialization of an optical disk having a diameter of 120 mm requires rotation of the disk from about 200 to 400, which is converted into time. Initialization time of about 30 to 60 seconds was required. For this reason, the initialization technique according to the prior art has a problem that the initialization time is redundant.
[0007]
In the initialization according to the prior art, as shown in FIG. 4, the initialization is started from the position of the light spot 50a on the optical disk 1, and after the optical disk 1 makes one rotation, it moves to the position of the light spot 50b. Initialization is performed by performing this spiral movement over the entire surface of the optical disc 1 without any gap between the light spots 50a and 50b. At this time, there is a difference in the peripheral speed due to the distance indicated by the initialization width 40 between the outer peripheral side position 20a and the inner peripheral side position 20b of the light spot. This peripheral speed difference naturally increases as the initialization width increases, and increases as the light spot moves to the center of the optical disc. This difference in peripheral speed appears as a difference in laser energy irradiated per unit area of unit time at initialization, which causes an increase in non-uniformity of initialization quality, and causes jitter characteristics and overwrite characteristics of optical disks. Is one of the factors that cause a decline.
[0008]
In addition, in the initialization according to the conventional technique, as shown in FIG. 3, it is possible to perform initialization at a high speed by connecting two or more light spots 10a in the radial direction. A significant difference in peripheral speed due to the distance indicated by the initialization width 30 occurs between the outer peripheral side position 20c and the inner peripheral side position 20d. This difference in peripheral speed appears as a difference in laser energy irradiated per unit area of unit time at the time of initialization, and causes a further increase in non-uniformity of initialization quality. Although FIG. 3 shows the case where there are two light spots, the same problem occurs when there are three or more light spots.
[0009]
That is, in the initialization method using one spot of about 200 μm in the radial direction as in the prior art, there is a problem that the initialization processing time becomes redundant, and the initialization method using a plurality of spots arranged in the radial direction. However, there is a problem that the non-uniformity of the initialization quality is further increased because the peripheral speed at the time of initialization is different between the outer peripheral side and the inner peripheral side as the initialization width becomes wider. In addition, when the initialization from the inner periphery toward the outer periphery was performed instead of the initialization from the outer periphery toward the inner periphery, there was the same problem as described above.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to eliminate the problems caused by the prior art, and to provide an initialization method of a phase change optical disk and an initialization apparatus using the initialization method that can be initialized at high speed and uniformly. is there.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a phase change in which the recording surface of the phase change optical disk is initially crystallized by irradiating the phase change optical disk having a non-crystallized recording surface with a high output light spot from an optical head. in the initialization process of the optical disc, 100Myuemu～250myuemu the n optical spot initial crystallization width L, at intervals of 2 [pi / n degrees placed in the same radial position, the initial crystallization width L in the radial direction of the disk and By moving the optical spot from the inner periphery to the outer periphery or from the inner periphery to the outer periphery and irradiating the light spot while maintaining the same distance between the light spot and the center of the disk, the n light spots are recorded. The first feature is to initialize the surface of the optical disk with the same radius without any gap.
[0012]
The present invention also relates to an initialization apparatus for a phase change optical disc that performs initial crystallization of the recording surface of the phase change optical disc by irradiating a phase change optical disc having a non-crystallized recording surface with a high output light spot from an optical head. , The optical head driving mechanism arranges n light spots of the initial crystallization width L at the same radial position with an interval of 2π / n degrees, and sets the initial crystallization width L in the disk radial direction from 100 μm to By moving the light spot from the inner periphery to the outer periphery or from the inner periphery to the outer periphery while irradiating the light spot while maintaining the same distance between the light spot and the center of the disk, the n light spots are formed. A second feature is that the recording surface is initialized at the same radius portion of the optical disk without any gap.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a phase change optical disk initialization method according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining an initialization operation of the phase change optical disc according to the present embodiment, and FIG. 2 is a diagram for explaining an initialization apparatus for realizing the initialization method according to the present embodiment.
[0016]
The initialization apparatus according to the first embodiment of the present invention includes a pair of optical head driving mechanisms as shown in FIG. 2 that are symmetrical with respect to a spindle that rotates and supports an optical disk 1, and a laser beam for initialization at a target position on the optical disk. Is irradiated. As shown in FIG. 2, the optical head driving mechanism includes a semiconductor laser 8 serving as a laser light source having a maximum output of 1 to 3 W, a collimating lens 9 that converts laser light emitted from the semiconductor laser 8 into parallel rays, A mirror 6 that reflects the laser light from the lens 9, a polarizing beam splitter 5 that passes the laser light reflected by the mirror 6 and polarizes reflected light that will be described later, and a laser beam from the beam splitter 5 A quarter wavelength recorder 4 for changing the phase, a condensing lens 3 for condensing laser light via the wavelength recorder 4, and driving the lens 3 to focus on the recording layer on the disk 1 A focusing mechanism 2 that performs control, and a laser beam polarized by 90 degrees by a polarizing beam splitter 5 is incident on the reflected light from the disk 1 through a condenser lens 3 and a quarter wavelength recorder 4 for focusing. A detector 10, and a moving mechanism for moving these mechanisms in the disk radial direction (not shown).
[0017]
The optical head driving mechanism configured as described above is configured to focus the initialization laser beam from the semiconductor laser 8 on the optical disc 1 through the mirror 6 to the condenser lens 3 and using the focusing mechanism 2. The phase change optical disk 1 is initialized by irradiating the spot 60 and moving the light spot 60 in the radial direction of the disk by a moving mechanism.
[0018]
In the initialization apparatus according to the present embodiment, a pair of the optical head driving mechanism is arranged with respect to the surface of the optical disc 1, and the position at which the two light spots 60 are irradiated at the initialization start point is spaced by an interval of 180 degrees. Are set at the same radial position, for example, the outermost peripheral position. That is, as shown in FIG. 1, the initialization apparatus irradiates oval light spots 60a and 60b on the position facing the straight line passing through the center on the optical disk 1 and the outermost peripheral position of the disk at the start of initialization. Set to the position to be used. The light spot preferably has an initialization width L of 100 μm to 250 μm in the disk radial direction and an oval shape of 1 μm to 4 μm in the track direction.
[0019]
Next, the initialization apparatus starts rotating the optical disc 1 and irradiating laser beams for initialization (light spots 60a and 60b), and keeps the light spots 60a and 60b at the same distance from the center of the disc. Then, the movement starts toward the center of the disc.
[0020]
The movement of the light spots 60a and 60b in the radial direction is controlled so that when the optical disc 1 is rotated halfway from the initialization start position (outermost circumference), the spots 60a and 60b move to the inner circumference by the initialization width 60. To do. That is, when attention is paid to the spot 60a as shown in FIG. 1, the light spot 60a so that the outer circumference of the spot 60a contacts the inner circumference side of the original spot 60b without a gap as shown by reference numeral 60a 'when half-circulated. Move in the radial direction. Similarly, the spot 60b moves in the radial direction.
[0021]
The initialization apparatus according to the present embodiment performs initialization in a range twice the initialization width 40 (L) as a result by performing one rotation of the optical disk 1, and continues this operation to perform disk radius spectroscopy. By moving the spot, initialization can be performed over the entire surface of the disk without a gap.
[0022]
Since the initialization apparatus according to the present embodiment performs initialization while rotating the two light spots 60ab arranged on the target spirally at the same speed on the optical disk, the light spot 60ab is irradiated onto the recording surface without any gap. Thus, initialization can be performed at high speed. That is, the initialization apparatus according to the present embodiment performs initialization at a high speed by substantially doubling the initialization width by arranging two light spots having a relatively small peripheral speed difference. Can do.
[0023]
In the above-described embodiment, an example in which two light spots are used has been described. However, the present invention is not limited to this. For example, three light spots are spaced by 120 degrees, four light spots are spaced by 90 degrees, and the like. When the number of spots is N, N light spots may be arranged at intervals of 360 degrees / N, and initialization may be performed while moving in the radial direction at the same speed. When the number of light spots is three or more, the substantial initialization width is N times, and a light spot that is substantially N times within the range of the peripheral speed difference by one spot is formed. Initialization can be performed at a higher speed while maintaining the characteristics. In this case, by reducing the initialization width of one light spot, it is possible to further prevent the above-described problems caused by the peripheral speed difference.
[0024]
Furthermore, in the embodiment, initialization is performed by rotating in a spiral manner so that two light spots do not overlap, in other words, an example in which the same portion of the optical disk is initialized only once by one light spot. However, the present invention is not limited to this, and when it is necessary to irradiate the same part of the optical disc twice or more with the light spots 60a and 60b due to the characteristics of the recording film, the irradiation is performed twice or more. You may comprise so that it may do. In this case, when n light spots are used, it is necessary to adjust the moving speed of each light spot in the radial direction. That is, it is necessary to determine the moving speed of the light spot in the radial direction according to the characteristics of the recording film of the optical disc.
[0025]
In addition, the initialization apparatus and method according to the present embodiment adjusts the radial movement speed of the light spot even if it is not possible to irradiate one light spot by arranging a plurality of light spots at equal angles. Specifically, when the radial moving speed in the case of one spot is V and the number of spots is N, the initialization can be performed over the entire surface of the optical disc by setting the spot speed to V / N. Also play.
[0026]
In the above embodiment, an example in which two optical head driving mechanisms are arranged on one surface of the optical disk has been described. However, the present invention is not limited to this, and a plurality of optical head driving mechanisms are arranged on both surfaces of the optical disk. In addition, one or a plurality of semiconductor lasers may be used as the light source without using a semiconductor laser for each optical head driving mechanism.
[0027]
【The invention's effect】
According to the present invention, in an initialization method and apparatus for a phase change optical disc that performs initial crystallization of the recording surface of the phase change optical disc, n light spots are arranged at the same radial position with an interval of 2π / n degrees. In addition, while maintaining the same distance between the light spot and the center of the disc, the initial crystallization is performed by moving from the inner periphery to the outer periphery or from the inner periphery to the outer periphery, so that the phase change can be performed quickly and uniformly. The optical disc can be initialized.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an initialization method according to an embodiment of the present invention;
FIG. 2 is a diagram for explaining a basic configuration of an initialization apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram for explaining an initialization method according to a conventional technique.
FIG. 4 is a diagram for explaining an initialization method according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Focus mechanism, 3 ... Focus lens, 4 ... 1/4 wavelength recorder, 5 ... Polarizing beam splitter, 6 ... Reflection mirror, 8 ... Semiconductor laser, 9 ... Collimating lens, 10 ... Photodetector, 60a and 60b ... light spots.

Claims (2)

In the method of initializing a phase change optical disk, in which the recording surface of the phase change optical disk is initially crystallized by irradiating a phase change optical disk whose recording surface is non-crystallized with a high output light spot from an optical head . The n light spots having the width L are arranged at the same radial position with an interval of 2π / n degrees, and the initial crystallization width L is set to 100 μm to 250 μm in the disk radial direction. By irradiating a light spot by moving from the inner periphery to the outer periphery or from the inner periphery to the outer periphery while keeping the distance the same, the n light spots move the recording surface at the same radius of the optical disk without any gaps. A method for initializing a phase change optical disc, characterized by initializing the phase change optical disc. In an initialization apparatus for a phase change optical disk that performs initial crystallization of a recording surface of a phase change optical disk by irradiating a phase change optical disk with a non-crystallized recording surface with a high output light spot from an optical head, an optical head drive The mechanism arranges n light spots having an initial crystallization width L at the same radial position with an interval of 2π / n degrees, and sets the initial crystallization width L to 100 μm to 250 μm in the disk radial direction. And the distance between the center of the optical disc and the center of the optical disc, while moving from the inner circumference to the outer circumference or from the inner circumference to the outer circumference to irradiate a light spot, the n light spots are applied to the recording surface of the optical disc. An initialization device for a phase change optical disc, wherein the same radius portion is initialized without a gap.

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