JPH10134392A - Initialization device and optical information recording carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably obtain an optical disk having little unevenness in the reflectance of the disk, the unevenness generating from the difference in a crystalline state in accordance with the intensity distribution of erasing light due to initialization SOLUTION: The ratio of the minimum to the maximum value of the intensity distribution, in the radial direction A of a beam shape 3 on a recording film, emitted from the optical pickup of an initialization device, is made 0.65 or above by incorporating for example a distribution correcting means for selecting distributed intensity of a light source or for optimizing an erase power; a high performance optical disk is thereby stably obtained which is free from appearing as the residual signal of a tracking error signal or free from developing abnormality of a disk.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an initialization apparatus and an optical information recording carrier in the field of optical information recording such as an optical disk and an optical card which enable large-capacity and high-density recording.

[0002]

2. Description of the Related Art At least in an optical disk for recording / reproducing or erasing information by light, a dielectric protection layer and a metal or metalloid recording layer are laminated on a disc-shaped resin substrate by vapor deposition or sputtering. In order to protect the recording layer and the protective layer, a protective coat of a resin is applied. Normally, a thin film formed by vapor deposition or sputtering in a recording film of a phase change material is in an amorphous state in which atoms and molecules are not regularly arranged. This amorphous state is also realized when the atoms and molecules are rapidly cooled from a molten state and frozen as a solid before atoms and molecules are regularly arranged. In many phase change type disks, the crystal state is set to an initial state, and after stacking films by vapor deposition or sputtering, initialization is performed to crystallize an amorphous film. In the initialization, most of the time, a semiconductor laser was used as the light source, and the light was focused on the disk surface and heated to a high temperature, so that the atoms and molecules that gained thermal energy moved to a stable position with a lower energy state and were arranged regularly. It becomes a crystalline state. In the conventional initialization device, the light of the semiconductor laser is focused on the recording layer of the disk and focused, the temperature of the recording film is raised, and the laser light is emitted from the inner circumference to the outer circumference of the disk or from the outer circumference to the inner circumference. And necessary areas are initialized.

By the way, in many cases, optical disks have tracks called guide grooves which are recorded in advance so that a laser beam of an optical disk device used for recording / reproducing or erasing correctly travels at a required position. Tracks include grooves and lands having a certain depth, discrete pits, recorded signals, and the like. When the laser beam of the optical disk device deviates from the track due to disturbance or the like, various servo mechanisms are provided to return the laser beam to a correct position. These servo mechanisms use changes in light reflected from the disk as signals. For example, in the tracking servo mechanism for the laser light of the optical disk device to travel correctly on the groove, for example, when the laser light is shifted to the left or right from the center of the groove, it changes to the reflected light amount due to the light diffraction phenomenon by the groove structure. Occurs. Utilizing this change in the amount of reflected light, a mechanism is provided for immediately returning the laser beam of the optical disk device to a normal position, that is, on the groove when the change occurs.

[0004]

FIG. 4 shows the beam shape on the recording layer surface emitted from the optical pickup of the initialization device. A semiconductor laser is used as a light source, the beam shape is flat, there are a longitudinal direction and a transverse direction, and several tracks are covered in the longitudinal direction by rotating the disk,
Scanning for initialization is performed in the direction perpendicular to the A-axis in FIG. FIG. 4A shows a relative intensity distribution of light in an A-axis cross section in FIG. Looking at the A-axis cross section, the distribution is not a Gaussian distribution but a trapezoidal distribution, and the trapezoid is substantially initialized at the upper bottom portion. In the case of a high-power semiconductor laser, the uniformity in the longitudinal direction (transverse mode) is not good, and the nonuniformity of the emission intensity occurs. Among the beams, in the prior art for initialization, the intensity distribution of the light emitted from the optical pickup of the initialization device is large, and the ratio of the minimum value to the maximum value of the intensity distribution is about 0.5 to 0.6. Therefore, there is a problem that a crystal state corresponding to the intensity distribution of the emitted light is different in a portion of the recording layer of the initialized disk, and a portion having a different reflectance is formed on the disk surface. In a portion where the light of high intensity is applied, the initialization is excessive, and when viewed at a low magnification with an optical microscope, a black streak-like non-uniform initialization portion can be observed. This portion is uneven in reflectance. If the disc itself has a greatly different reflectivity, the laser beam of the optical disc device is located at the center position on the groove, but it seems as if it is running off the center of the groove due to the difference in reflectivity. The information is detected by the optical disk device and appears as a residual signal of the tracking error signal. Further, in some cases, the disk is recognized as abnormal. The uniformity of the amount of light reflected from the disk is also important in the optical disk device in order for the laser beam to travel correctly at a predetermined position.If the reflectance is uneven on the disk, a tracking error signal will remain. There were problems such as appearing on the disk and the disk becoming abnormal.

In order to alleviate the difference in crystal state due to the intensity distribution of the light emitted from the optical pickup of the initialization device, the portions where the light travels in the first and second rounds are superimposed on the disk surface. If the same part is initialized a plurality of times, the light emitted from the optical pickup of the initialization device is shifted from the inner circumference to the outer circumference due to the unevenness of the feed pitch of the initialization laser head feeding mechanism of the initialization device and the intensity distribution of the laser beam. Or, in the overlapping state of light generated when moving sequentially from the outer periphery to the inner periphery, a difference in the crystal state causes a portion having a different reflectance on the disk surface, which appears as a residual signal of the tracking error signal. There was a problem. If the residual component of the tracking error signal exceeds a certain value, there is a problem that the disk is recognized as being abnormal.

[0006]

In the initialization apparatus according to the present invention, the distribution of the light source is selected, the erasing power is optimized, and the distribution correction means is inserted. The ratio of the minimum value to the maximum value of the radial intensity distribution of the emitted light beam on the recording film in the radial direction is set to 0.65 or more. According to the present invention, the reflectivity unevenness of the disk generated from the difference in the crystal state according to the intensity distribution of the light beam is small, and when applied to an optical disk device, it appears as a residual signal of a tracking error signal, A high-performance optical disk that does not become abnormal can be stably obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention has an optical pickup comprising at least a light emitting section and an objective lens, means for moving the optical pickup in a radial direction, and an optical recording film. An initialization device that has a mechanism for holding and rotating the optical information recording carrier and irradiates the information recording carrier with light emitted from the optical pickup to change the state of the information recording layer; The light beam irradiated on the film is anisotropic, the intensity distribution of the radial cross section of the information recording carrier of the anisotropic light beam has a substantially trapezoidal intensity distribution, The ratio of the minimum value to the maximum value of the relative light intensity distribution in the upper bottom portion of the trapezoid is 0.65 or more, and when initialized by this initialization device, the light beam intensity distribution becomes Difference in crystal state according to The effect that the unevenness of the reflectivity of the generated disk is small and a high-performance optical disk that does not appear as a residual signal of a tracking error signal or cause a disk abnormality when applied to an optical disk device can be stably obtained. Having.

According to a second aspect of the present invention, in carrying out the first aspect, the light source used for the light emitting portion of the initialization device is configured such that an emitted light beam has an anisotropic shape, and The intensity distribution of the light beam in the radial cross section of the information recording carrier has a substantially trapezoidal intensity distribution, and the ratio of the minimum value to the maximum value of the relative light intensity distribution of the upper bottom portion of the trapezoid is 0.65 or more,
When initialized by this initialization device, the reflectance unevenness of the disk generated from the difference in crystal state according to the intensity distribution of the light beam is small, and when applied to an optical disk device, it appears as a residual signal of a tracking error signal, It has an effect that a high-performance optical disk that does not cause a disk abnormality can be stably obtained.

According to a third aspect of the present invention, in carrying out the first aspect, the light beam on the information recording layer at the initialization power among the initialization conditions of the initialization device has an anisotropic shape. The intensity distribution in the radial cross section of the information recording carrier of the isotropic light beam has a substantially trapezoidal intensity distribution, and the minimum value with respect to the maximum value of the relative light intensity distribution of the upper bottom portion of the trapezoid. The initialization power is selected such that the initializing power is 0.65 or more. When the initialization is performed by the initialization device, the disk is generated from a difference in crystal state according to the intensity distribution of the light beam. When it is applied to an optical disk device, it has an effect that a high-performance optical disk which does not appear as a residual signal of a tracking error signal and does not cause a disk abnormality can be stably obtained.

According to a fourth aspect of the present invention, in carrying out the first aspect, the information recording carrier to be initialized is not at a focal position focused by an objective lens. When initialized by this initialization device, the reflectance unevenness of the disk generated from the difference in crystal state according to the intensity distribution of the light beam is small, and when applied to an optical disk device, it appears as a residual signal of a tracking error signal, It has an effect that a high-performance optical disk that does not cause a disk abnormality can be stably obtained.

According to a fifth aspect of the present invention, a means for detecting a relative light intensity distribution of light is provided to an incident optical system from a light source of a light emitting section to an objective lens, and the distribution is determined based on the detected relative light intensity distribution. After the relative light intensity distribution is corrected, or the initialization is performed while correcting the relative light intensity distribution. The reflectance unevenness of the disk generated from the difference in crystal state is small, and when applied to an optical disk device,
The optical disk has a function of stably obtaining a high-performance optical disk which does not appear as a residual signal of the tracking error signal and does not cause an abnormality in the disk.

[0012] The invention described in claim 6 is the first or second invention.
An optical information recording carrier initialized by the initialization device according to any one of 3, 4, and 5, wherein the reflectance unevenness of the disk caused by the difference in the crystal state according to the light intensity distribution. When used in an optical disk apparatus, the optical disk apparatus has a function of stably obtaining a high-performance optical disk that does not appear as a residual signal of a tracking error signal and does not cause a disk abnormality.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. FIG. 1 shows the relative intensity distribution of the light emitted from the optical pickup of the initialization device on the recording layer surface. FIG. 1 (A) shows the relative intensity distribution in the A-axis cross section in FIG. 1, and FIG. 1 (B) shows FIG. 5 shows the relative intensity distribution of the B-axis cross section at. 1 is a disk, 2 is a track, and 3 is a beam shape on the recording layer surface. In order to increase the efficiency of the initialization, the longitudinal direction of the emitted light is set to the radial direction of the disk, and the shorter direction is set to the track direction. With one rotation of the disk, the recording layer in a region near the width in the longitudinal direction of the emitted light changes from an amorphous state to a crystalline state. The width to be crystallized depends on the power and linear velocity during initialization, or the light absorption and thermal conductivity due to the film configuration of the disc, and closely relates to the temperature distribution on the recording layer and the temperature rise / fall time. Involved. As shown in FIG. 1A, in the embodiment of the present invention,
Since the ratio of the minimum value to the maximum value of the intensity distribution in the radial direction of the light emitted from the initialization device is 0.65 or more and the relative light intensity distribution is very small, it is affected by the feed pitch unevenness of the feed mechanism of the initialization device. When sending the laser head sequentially from the inner circumference to the outer circumference or from the outer circumference to the inner circumference, just consider that there is no space and the uninitialized part is not enough. The difference in reflectance due to the difference in crystal state depending on the location is small, and in disk production, an initialization device with a large margin for the initialization power and linear velocity can be obtained, and the disk initialized by the initialization device is The dispersion of the reflectance on the disk surface is small, and when applied to an optical disk device, it does not appear as a residual signal of a tracking error signal or cause a disk abnormality. Performance optical disk was obtained stably. The semiconductor laser used for the initialization device has a different intensity distribution for each individual. Further, among the initialization conditions, the intensity distribution differs depending on the set power. In consideration of the above, it is preferable to select a semiconductor laser having a small intensity distribution variation, or to select a power setting having a small intensity distribution variation among initialization conditions. After that, taking into account the linear velocity of initialization, so as to satisfy the disk conditions such as the reflectance and mechanical characteristics of the disk,
An optical disk satisfying various characteristics was obtained. Such an initialization apparatus can be applied not only to a phase change between an amorphous phase and a crystal phase but also to a change in the crystalline state of a recording film such as a phase change between a crystal and a crystal. Even when a magneto-optical recording film is used, the same effect can be obtained only by adding a means for generating a magnetic field.

FIG. 2 shows an example of an optical system for detecting a relative light intensity distribution of light and controlling a distribution correction plate based on the result. The light emitted from the semiconductor laser 4 is collimated by a collimating lens 5, the light split by a beam splitter 6 is received by an image sensor 7, and a distribution correction plate 8 is controlled according to the result. The distribution correction plate is composed of a liquid crystal cell, and is controlled so as to reduce the transmittance of a beam in a portion where the intensity of the semiconductor laser is high. Although the liquid crystal cell and the image sensor have a large number of elements, the part for controlling is treated as an amplifier 11 for simplicity in the figure, but in actuality, according to the required correction accuracy, The number of elements can be varied. In the embodiment, the diameter of the parallel light beam is set to 5 mm, the number of elements of the image sensor is 10 × 10 = 100, and the number of liquid crystal cells is similarly configured to form a simple correction system. Was completed. Also, the sum of the outputs of the image sensor at this time can be calculated and used for erasing power control. By performing initialization with the initialization device having such a configuration, it is possible to suppress variations in the relative intensity distribution on the recording layer surface, and the difference in reflectance due to the difference in crystal state depending on the location on the disk surface is small. In disk production, an initialization device with a wide margin for the initialization power and linear velocity can be obtained, and a disk initialized by the initialization device has a small variation in reflectivity on the disk surface, so that it cannot be used in an optical disk device. In such a case, a high-performance optical disk which does not appear as a residual signal of the tracking error signal or cause a disk abnormality was stably obtained. The distribution correction plate need not be a liquid crystal cell as long as its transmittance can be controlled according to the intensity of light.

FIG. 3 shows a case where the information record carrier to be initialized is not at the focal position focused by the objective lens.
2 shows a relative intensity distribution of a cross section and a B section. In this case, FIG.
The relative intensity distribution of the A section of FIG.
A relative intensity distribution is obtained. That is, by displacing the information recording carrier from the focal point of the objective lens, the intensity distribution in the A section can be made uniform. In normal cases, the position of the objective lens and the optical disk is adjusted so that the recording layer surface of the optical disk to be initialized comes to the focal position where the light is most narrowed down, and the focusing servo mechanism is always stably maintained at this distance. The temperature of the recording layer surface of the disk can be raised efficiently even at low power and high linear velocity, but the focusing servo mechanism of the initialization device is electrically offset and the optical system of the head is detected. The relative light intensity distribution of light can be improved by shifting the focal position from the recording layer surface by shifting the point or the like. In such defocusing, the relative intensity distribution of light on the disk surface in the longitudinal direction can be improved, and as shown in FIG. , The recording layer has a slow cooling effect. When light in the lateral direction spreads, the temperature distribution of the recording layer also expands in accordance with the spread of the light. If the recording layer is rapidly cooled after the temperature rises before the heat spreads, the intensity distribution of the initialization beam,
The crystal state corresponding to the unevenness of the overlapping of the beams caused by sequentially moving the beams is frozen. However, when the temperature is gradually cooled after the temperature is raised and the temperature rise time becomes longer, the heat spreads, and atoms or molecules constituting the recording layer can move to a stable place with lower energy,
The influence of the intensity distribution of the initialization beam and the uneven beam overlap caused by the relative movement of the beam was alleviated, and an optical disk with little variation in crystal state and small uneven reflectance was obtained.

[0016]

As described above, according to the present invention, the light beam irradiated on the recording film of the information recording carrier has an anisotropic shape,
The intensity distribution of the information recording carrier in the radial cross section of the anisotropic light beam has a substantially trapezoidal intensity distribution, and the maximum value of the relative light intensity distribution of the upper bottom portion of the trapezoid. By configuring the ratio of the minimum value to be equal to or greater than 0.65, the unevenness of the reflectivity of the disk caused by the difference in the crystal state according to the light intensity distribution of the initialization device is small. An advantageous effect is obtained in that a high-performance optical disk that does not appear as a residual signal of the tracking error signal and does not cause an abnormality in the disk can be stably obtained.

[Brief description of the drawings]

FIG. 1 is an intensity distribution diagram on a recording layer surface of light emitted from an initialization device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical system that controls a distribution correction plate according to an embodiment of the present invention.

FIG. 3 is a relative intensity distribution diagram when an information recording carrier is not at a focal position according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a beam shape on a recording layer surface emitted from a conventional initialization device.

[Explanation of symbols]

 Reference Signs List 1 disc 2 guide groove 3 beam shape 4 semiconductor laser 5 collimating lens 6 beam splitter 7 image sensor 8 distribution correction plate 10 disc

Claims (6)

[Claims] 1. An optical pickup comprising at least a light emitting unit and an objective lens, means for moving the optical pickup in a radial direction, and a mechanism for holding and rotating an optical information recording carrier having an optical recording film. An initialization device for irradiating the information recording carrier with light emitted from the optical pickup to change the state of the information recording layer, wherein the light beam irradiated on the recording film of the information recording carrier has an anisotropic shape. The intensity distribution of the anisotropic light beam in the radial cross section of the information recording carrier has a substantially trapezoidal intensity distribution, and the maximum value of the relative light intensity distribution of the upper bottom portion of the trapezoid. The ratio of the minimum value to the minimum value is 0.65 or more. 2. A light source used for a light-emitting portion of an initialization device, wherein an emitted light beam has an anisotropic shape, and an intensity distribution of the anisotropic light beam in a radial cross section of the information recording carrier is determined. 2. The method according to claim 1, wherein the trapezoid has a substantially trapezoidal intensity distribution, and a ratio of a minimum value to a maximum value of a relative light intensity distribution in an upper bottom portion of the trapezoid is 0.65 or more. Initialization device. 3. A light beam on an information recording layer at an initializing power of an initializing condition of an initializing device has an anisotropic shape;
The intensity distribution of the information recording carrier in the radial cross section of the anisotropic light beam has a substantially trapezoidal intensity distribution, and the maximum value of the relative light intensity distribution of the upper bottom portion of the trapezoid. 2. The initialization apparatus according to claim 1, wherein an initialization power whose minimum value ratio is equal to or greater than 0.65 is selected. 4. The initialization apparatus according to claim 1, wherein the information record carrier to be initialized is not at a focal position focused by an objective lens. 5. An incident optical system from a light source of a light emitting section to an objective lens, comprising means for detecting a relative light intensity distribution of light, and means for correcting the distribution based on the detected relative light intensity distribution,
2. The initialization apparatus according to claim 1, wherein the initialization is performed after or while correcting the relative light intensity distribution. 6. An optical information recording medium initialized by the initialization device according to claim 1.