JPH09312036A - INFORMATION RECORDING MEDIUM, ITS INITIALIZATION METHOD, AND INITIALIZATION DEVICE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of surely recording information irrespective of the number of overwriting times by providing an incoherent initializing light source, a means for rotating or moving a recording medium and a means for converging optical beams or passing a portion of these beams. SOLUTION: Light beams are continuously emitted from the high output halogen lamp 9 having an output of about 3KW and a spot shaped of beams emitted form the high output halogen lamp 9 is formed to be a long circular spot 10 of about 5×25cm in a recording film surface. The beams are shaped by a reflection mirror 11 and a lens 12 and the long axial direction of the long circular sport 10 is placed nearly perphendiularly to a recording track direction. Beam power is set for melting the recording film, a disk 14 is rotted by a motor 13 at a linear speed of 10m/s and while moving the long circular spot 10 from the outer periphery of the disk to its inner periphery at a constant speed and irradiation is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium, an initialization method thereof, and an initialization device.

[0002]

2. Description of the Related Art In a phase-change type optical disk for recording information by utilizing a phase change between crystal and amorphous, high speed erasing which can be crystallized in about the same time as a laser irradiation time for recording is possible. When a recording film is used, the existing information is changed by changing the power of one energy beam between two levels that are both higher than the read power level, that is, between a high power level and an intermediate power level. It is possible to perform so-called overwriting (rewriting by overwriting) in which new information is recorded while erasing. Immediately after such a recording film is formed by a vacuum deposition method, a sputtering method or the like (as depo. State), at least a part thereof is in an amorphous state or in a metastable crystalline state. Such an as depo. State usually has low reflectance, and autofocus and tracking are likely to be unstable. Therefore, the recording film is initialized in advance.

Conventionally, as one of the means for this initialization,
As in Japanese Patent Publication No. 2-45247, for example, a laser beam of an argon laser is used as an elliptical light spot,
Irradiation was performed so that the longitudinal direction thereof substantially coincided with the radial direction of the recording medium, and the recording film was crystallized in a temperature range from the crystallization temperature to the melting point.

Further, initial crystallization on the entire surface by flash light irradiation using a xenon lamp has also been studied.

[0005]

When the information recording medium is initialized by using the conventional technique, the recording film is crystallized at 400 to 500 ° C., which is lower than the melting point, so that the crystal grains are entirely dispersed. The crystallization speed is small and the crystallization speed after the initial overwriting is slightly slow, and the crystallization speed is increased by rewriting by overwriting 100 times and gradually reaches a steady state.
Therefore, if the recording waveform is determined so that optimum recording / reproduction can be performed after the steady state is reached, in the initial overwrite, the reproduction signal waveform, especially in the time axis direction of the portion corresponding to the trailing end position of the recording mark Shifts and fluctuations (jitter) are large, and it becomes maximum after overwriting 2 to 5 times
It becomes smaller by the number of times and then reaches a steady state. Therefore, if the number of overwrites is 2 to 100, a read error may occur in some cases.

Such a change in crystallization rate causes film formation,
It is considered that a disordered interatomic bond is large in a recording film that has just been crystallized, the crystallization speed is limited, and the disorder is gradually reduced by melting the film during recording.

Further, in the prior art device, the device is complicated, for example, the laser beam emitted from the Ar laser is separated into two spots for initialization, and the initialization device is expensive because the laser is expensive. There was a problem that was.

It is an object of the present invention to provide an information recording medium capable of surely recording information regardless of the number of overwrites, an initialization method and an initialization device therefor.

[0009]

In order to solve the problems in the prior art, in the initialization method of the present invention, an incoherent (not stimulated emission) high output light source capable of continuous light emission, such as a halogen lamp, is used. (Output about 2KW)
The beam is shaped so that the beam spot for initialization emitted from this high-power light source is rectangular, elliptical, or fan-shaped on the surface of the recording film. ) Is arranged so as to be substantially perpendicular to the recording track direction, and the recording medium is rotated or moved to focus and irradiate on the recording film. Then, if necessary, the initialization beam is moved in the radial direction of the recording medium to perform initialization.

In the present invention, at least a part of the recording film is
One of the characteristics is that the maximum width of the beam spot on the disk emitted from the high-power initialization light source is larger than the recording track pitch, and the melting process is performed by the irradiation of the high-power initialization beam. A filament arc tube such as a halogen lamp, a discharge tube such as a xenon lamp, or a mercury lamp is used as the high-power initialization beam.

The light generated from the high-power light source includes a reflecting mirror, a lens, a rotary chopper (a shutter may be used) for controlling the irradiation time on the recording medium, and a mask (slit) for passing a part of the light. Initialization may be performed by using one or more of them to form a beam so as to hit an area of 1/10 or less, more preferably 1/100 or less, instead of the entire surface of the recording medium.

Here, one of the reasons for reducing the irradiation area is to shorten the irradiation time per time and to avoid the damage of the recording medium due to heat. Another reason is that even a light source having a relatively small output can be sufficiently heated by condensing.

The temperature of the recording film reaches the melting point or higher by irradiation with a halogen lamp or the like, the recording film is melted, and then cooled. Thereby, the atomic arrangement of the recording film became stable, and good characteristics were obtained from the first overwriting.
Here, since the cooling rate of the recording film is lower than the cooling rate at the time of recording on the disk, after the recording film is melted, it is at least partially recrystallized into a crystalline state. When the recrystallized region is small in a recording film with a low crystal growth rate, laser beam irradiation in the temperature range above the crystallization temperature and below the melting point, weak continuous light irradiation with a halogen lamp, flash light irradiation, etc. are performed to record. The film may be crystallized. At this time, when the recording film is melted and then recrystallized, a crystalline state of a coarse crystal grain size with a uniform maximum width of 0.1 μm or more (larger than the crystal grain form after erasing the recording mark) is obtained over the entire surface of the disc. There is a possibility that The width of the coarse crystal grain region corresponding to one irradiation of the initialization energy beam at this time is wider than the recording track width.

In order to reduce the damage due to heat by such initialization, the rectangular spot used in the example of the present invention is shaped by the optical system in the initialization device so that it is in the short axis direction (short direction). ) Has a narrow spot width, and the cross-sectional shape of the light intensity distribution in the major axis direction (longitudinal direction) is trapezoidal (the vertex is flat).
It has a shape close to. Then, the disk is rotated in a state where the major axis direction (longitudinal direction) of the rectangular spot is substantially perpendicular to the recording track direction, and initialization is performed so that the beam focal point is substantially on the recording film. Was. By rotating the recording medium at a high speed, rapid heating and rapid cooling are possible, and damage due to heat can be reduced.

Here, by making the maximum width of the initialization beam spot on the disc larger than the recording track pitch, the time required for the initialization can be shortened. For example,
Output 3K to enable initialization of a large area in a short time
A halogen lamp of W was used to shape the beam so that the shape of the beam spot was a rectangular spot of about 5 mm × 40 mm on the surface of the recording film. Then, the disk was irradiated while the disk was rotated at a high speed in a state where the long-axis direction (longitudinal direction) of the rectangular spot was arranged in a direction substantially perpendicular to the recording track direction (disk radial direction). As a result, for example, if initialization is performed by rotating a disk having a diameter of 12 cm at 3600 rpm,
The initialization will be completed in less than 1 second.

In order to securely initialize the entire surface of the disk, it is sufficient to increase the beam irradiation power density from the inner circumference to the outer circumference by using a neutral density filter or the like having different transmittance depending on the location. If you use a mask with slits to make the light spot a rectangular shape that spreads out in the radial direction of the disk (preferably the shape of the paper part when the fan is slightly opened), you can use a mask without slits. It can be initialized uniformly from the circumference to the circumference.

Further, in order to further reduce the thermal damage to the recording film, the shape of the beam spot should be a fan-shaped spot having a width of about 0.5 mm and a length of about 5 cm where the beam spot is narrow on the disk surface. The beam is shaped into a beam and the number of irradiations on the disk surface is limited to 50 times or less by using a shutter or the like. Further, when pulsed by a rotary chopper, the rotation of the disk is kept at a constant rotational angular velocity (CAV), the linear velocity of the outermost circumference at this time is v, the half-width of the initialization beam in the recording track direction is x, and on the disk is When the pulse irradiation frequency of the initialization beam is f, the initialization can be performed in a uniform state over the entire initialization region by performing the initialization under the condition that f ≧ (v / x) is satisfied. In the case of such initialization by pulse irradiation, a large number of arcs are gathered at least on one side edge of the coarse grain region at the boundary between the initialized region and the uninitialized region. The shape.

Further, depending on the recording medium, first, the beam power is irradiated so that the temperature is lower than the melting point of the recording film, and thereafter, the beam power is at least two steps of the beam power at which the temperature is equal to or higher than the melting point at which the recording film melts. It may be better to irradiate. Alternatively, the irradiation may be initialized by first irradiating with beam power having a temperature equal to or higher than the melting point of the recording film, and then irradiating with beam power having a temperature lower than the melting point of the recording film.

A wavelength region of a high power light source for initialization,
There is a case where the laser wavelength for actually reading information is different. At this time, the reflectance in the as depo. State at the central wavelength of the light source for initialization or the reflectance in the amorphous state is the reflectance in the as depo. State at the wavelength of the laser for actually reading information or By using a recording medium having a reflectance of 3 times or less in the amorphous state, reliable initialization and good recording characteristics were obtained. Especially 1.5
It is preferable that the number is twice or less.

The present invention can also be applied to the case of initializing an optical disk medium which enables a high density reproduction or recording by providing a mask layer which causes a region where the amount of light transmission decreases in the beam spot. For example, when a dye is used as the mask layer or when an inorganic layer having a low melting point is used. Further, the present invention can be applied to a case where a mask layer for generating a region where the amount of light transmission decreases in a beam spot is provided to initialize an optical disk medium capable of high-density reproduction or recording. For example, when a dye such as naphthalocyanine is used as the mask layer, or when an inorganic layer having a low melting point is used.

The initialization device used in the present invention uses an incoherent initialization light source capable of continuous light emission, and has means for rotating or moving the recording medium and means for focusing the initialization beam on the recording film. Have at least. Further, in addition to the above-mentioned means, means for shaping the beam emitted from the initialization light source into a rectangular spot, and positioning of the recording head for arranging the major axis direction of the rectangular spot in a direction substantially perpendicular to the recording track direction. Means, means for moving the position of the initialization beam on the recording medium, means for controlling the mutual relationship between rotation or movement of the recording medium and radial movement of the recording beam for the initialization beam, power level of the initialization beam Also, at least one of the means for controlling the irradiation time and temporarily melting the recording film may be provided.

In the present invention, at least a protective layer on the substrate,
A recording medium having an optical recording film, an intermediate layer, and a reflective layer formed in this order is used. At this time, good characteristics were obtained by setting the thickness of each layer in the following range. First, the thickness of the protective layer is 50
The thickness is preferably from 150 nm to 150 nm, particularly preferably from 60 nm to 130 nm. The thickness of the optical recording film is 10 n
m to 50 nm, preferably 12 nm to 40 nm.
nm or less is preferable. The thickness of the intermediate layer is 5 nm or more and 50
nm or less, preferably 10 nm or more and 30 nm or less. The thickness of the reflective layer is preferably from 30 nm to 400 nm, particularly preferably from 50 nm to 300 nm.

The recording film used is a crystal-amorphous phase change optical recording film capable of high-speed crystallization, a recording film utilizing a change between amorphous-amorphous, a change in crystal system and crystal grain size, etc. Although the crystal-to-crystal phase change recording film of is preferable, other recording films may be used. In particular, Ge-Sb-Te based recording films and Ag-In-Sb
A recording film using a phase change, such as a -Te recording film, may be used. In addition, a recording film in which a high melting point material such as Cr ₂ Te ₃ having a higher melting point than the main component material is added to the recording film,
It is preferable to use a recording medium having two reflective layers, because it is possible to suppress a change in the thickness of the recording film due to the flow of the recording film.

Here, the thickness of the first layer is preferably 20 nm or more and 300 nm or less when the reflective layer has two layers.
Particularly, the thickness is preferably from 50 nm to 100 nm. The thickness of the second layer is preferably 30 nm or more and 400 nm or less, and particularly preferably 50 nm or more and 300 nm or less.

It is preferable that the operation of melting the recording film is performed after forming each layer such as the recording film on the substrate and applying a protective coat such as an ultraviolet curable resin, because the recording film is less damaged. In particular, after the optical recording medium having a structure coated with a protective layer of an ultraviolet curable resin and the protective plate are adhered to each other by an adhesive such as an ultraviolet curable resin or a hot melt method, laser irradiation or halogen is applied from the substrate side. It is preferable to perform continuous irradiation with a lamp or the like, or flash light irradiation with a xenon lamp or the like. Alternatively, irradiation may be performed on both surfaces after the optical recording media are adhered to each other to form a double-sided recording medium.

In the initialization of the present invention, at least a part of the recording film has once undergone a melting process by irradiation with an initialization beam. The energy source for melting the recording film is incoherent capable of continuous light emission. Halogen lamps, xenon lamps, mercury lamps, etc. can be used. Further, even at a temperature slightly below the melting point of the recording film (within 100 ° C. below the melting point), if the number of irradiations at one location is doubled or more, an effect similar to that of melting is obtained. Since the recording film is in an amorphous state before the irradiation with the energy beam, there is actually no clear melting point, and when it is rapidly cooled, it does not crystallize but softens from a temperature slightly below the melting point of the crystal. When fine crystals are formed during the temperature rise, they melt at a temperature slightly lower than the melting point (melting point of large crystals) which is usually known. Therefore, it is considered that the effect is effective even just below the melting point. It can be known from the fact that when such a temperature is reached, coarse crystals are usually formed during cooling.

The operation of melting the recording film is performed at the same time as certifying the recording medium (defect inspection by reading).
Alternatively, it may be performed before or after that. Then, the above-described operation of melting the recording film or raising the temperature to a temperature slightly lower than the melting point is performed at the stage when the manufacturer manufactures the recording medium (related to the manufacturing method), or trial writing is performed by an apparatus that actually records / reproduces information. It suffices to go to the front (related to the pretreatment method).

Further, the present invention is not limited to the disk shape,
The present invention is also applicable to other forms of recording medium such as a card.

[0029]

1 is a structural sectional view of a rewritable optical disk having a guide groove used in this embodiment. First diameter 120 mm, thickness of 0.6mm of the guide groove (track pitch 1.48 .mu.m, U-shaped grooves) on the polycarbonate substrate 1 having the form ZnS-SiO ₂ protective layer 2 having a thickness of about 110nm by magnetron sputtering did. Next, a recording film 3 having a composition of Cr ₂ Ge ₂₀ Sb ₂₂ Te ₅₆ was formed to a thickness of about 25 nm. Next, Zn
To form S-SiO ₂ intermediate layer 4 to a thickness of approximately 20 nm.
Further, the Si layer (first reflection layer) 5 is further formed with 80 nm and Al.
-A Ti layer (second reflective layer) 6 was formed to a thickness of about 100 nm. These films were formed sequentially in the same sputtering apparatus. Thereafter, an ultraviolet-curable resin layer 7 was applied thereon, and then adhered to another disk having the same structure with a two-liquid mixed room-temperature-curable adhesive 8.

The disk thus produced was initialized as follows. First, as shown in FIG. 2, a high-power halogen lamp 9 with an output of about 3 KW is continuously emitted, and a beam is emitted from the reflecting mirror so that the spot shape of the beam becomes an elliptical spot 10 of about 5 mm × 25 cm on the recording film surface. The beam is shaped by the lens 11 and the lens 12, and the major axis direction of the elliptical spot 10 is arranged substantially perpendicular to the recording track direction. The shape of the reflector is part of an elliptic cylinder so that the halogen lamp and the disk surface are on the two focal points of the ellipse. The elliptical spot had a width of 5 mm and a length of 25 cm. The width is preferably 2 mm or more and 10 mm or less, and the length is preferably 5 cm or more and 50 cm or less.

Then, the disk 14 is rotated at a linear velocity of 10 m / s by the motor 13 and the elliptical spot 10 is moved from the outer circumference to the inner circumference of the disk at a constant speed, and the beam power is set to a power at which the recording film melts. And then irradiated. By providing a shutter between the light source and the disc on the light source side and a slit on the disc side that further limits the width direction of the elliptical light spot, the irradiation time can be shortened and damage to the disc such as cracks due to heat can be avoided. I liked it.

The shutter is of a rotary type, and has one paper-shaped opening of a fan slightly opened. You may have two or more. When the lateral line of the fan-shaped opening is extended, it extends almost through the center of rotation. Further, the rotation center of the shutter was set at substantially the same position as the rotation center of the disk. This is particularly preferable because the disk can be initialized uniformly from the inner circumference to the outer circumference. Normally, the opening of the shutter passes once through the portion of the condensed light beam to stop it. However, if the rotation is continued and passed a plurality of times, the initialization can be sufficiently performed although it takes time. The time taken for the shutter opening to pass through a stationary point in the light beam was 0.5 seconds. Good initialization was performed for 100 ms or more and 1 second or less. Narrow the opening of the shutter,
Continuous pulse irradiation is also possible if a plurality of rotary choppers are used.

As the slit, a slit whose width is proportional to the radius of the disk and which is opened in a fan shape in the radial direction was used. This is preferable because the irradiation light amount can be made substantially the same at any portion in the radial direction. The widest part of the slit was 0.3 mm. If it is 1 mm or less, the damage to the disc is small. It is particularly preferable if it is 0.5 mm or less. The length of the slit is preferably slightly longer than the radial length of the recording area. The initialization machine has a mechanism for bringing a mask having a slit close to the disc after rotating the disc, and the mask causes the mask to move from the disc to 0.3.
mm ascended. The flying height is preferably 0.1 mm or more and 1 mm or less, and more preferably 0.2 mm or more and 0.5 mm or less.

It is preferable that the lens 12 is located closer to the light source than the shutter because the light can be condensed easily, but the lens may be omitted.

In the case of pulse irradiation using a chopper, initialization was performed under the conditions of a linear velocity of the disk of 10 m / s, an irradiation pulse frequency of 5 KHz on the disk surface, and an irradiation pulse duty ratio of 50%. For comparison, initial crystallization by irradiation with semiconductor laser light was also performed.

For recording on the initialized disc, overwriting was performed with a ternary waveform shown in FIG. 3 using a recording device having a laser wavelength of 680 nm and an NA of 0.55. Here, the recording power was 9 mW, the erasing power was 4 mW, and the reading power was 1 mW. FIG. 4 shows the results of examining the dependence of jitter on the number of overwrites in each initialization region.

From these figures, it is understood that in the case of the initial crystallization by irradiation with the semiconductor laser light, the jitter becomes large in the case where the number of overwrites is small. As a cause of this, in the case of initial crystallization by irradiation with semiconductor laser light, the temperature until the recording film melts has not reached,
It is considered that the structure of the recording film gradually changed due to overwriting because the recording film was crystallized from the as depo. State without melting. On the other hand, in the case of initialization with a halogen lamp, the recording film temperature reached the melting point, and once the recording film melted, it was recrystallized during cooling and most of it became a crystalline state. It is considered that good characteristics are obtained from the above. If coarse crystal grains are formed at this time, the width of the coarse crystal grain region is wider than the recording track width.

In the present invention, the value of each power level, the pulse irradiation frequency of the beam, the linear velocity of the disk, etc. may be changed according to the crystallization speed of the recording film and the cooling speed of the recording film. For example, the linear velocity of the outermost circumference of the recording medium at the time of initialization is v [m / s], the half width of the initialization beam in the recording track direction is x [μm], and the pulse irradiation frequency of the beam on the disk is f [ MHz], f ≧
Initialization was performed so that the condition (v / x) was satisfied. As a result, initialization can be performed in a uniform state over the entire initialization area.

In the initialization method of the present embodiment, when pulse irradiation with a high initialization pulse frequency is performed, pulsed light is continuously irradiated at a short distance, so that the cooling rate of the recording film is slow. Coarse crystals are formed over the entire initialization region by recrystallization. In the case of pulse initialization, at least one edge of the coarse crystal grain region at the boundary between the initialized region and the non-initialized region is
It becomes a shape where a large number of arcs are gathered.

Depending on the recording medium, first, the beam power is irradiated so that the temperature is equal to or lower than the melting point of the recording film, and thereafter, the beam power is changed into a plurality of stages at which the temperature is equal to or higher than the melting point at which the recording film is melted. It may be better to irradiate with. On the contrary, the initialization may be performed by first irradiating with beam power having a temperature equal to or higher than the melting point of the recording film, and then irradiating with beam power having a temperature equal to or lower than the melting point of the recording film.

When the recording film is recrystallized after melting, coarse crystal grains are generated. Good recording / reproducing characteristics were obtained by using the recording medium and the initialization method in which the maximum width of the coarse crystal grains is about 0.5 μm. The maximum width is preferably about 0.1 μm or more, and more preferably 0.3 μm or more, which is close to the maximum width of coarse crystal grains formed during actual overwriting. However, it is preferable not to exceed 5 μm.

The present invention can also be applied to the case of initializing an optical disc medium capable of high-density reproduction or recording by providing a mask layer for producing a region where the light transmission amount is reduced in the recording or reproduction beam spot. For example, when a dye is used as the mask layer or when an inorganic layer having a low melting point is used. Furthermore, the present invention can be applied to the case of initializing an optical disk medium capable of reproducing or recording high density recording information by providing a mask layer that causes a region where the laser beam does not penetrate to the recording film in the beam spot. For example, when a pigment such as phthalocyanine is used as the mask layer, or when an inorganic layer having a low melting point is used.

The initialization device used in this embodiment is a halogen lamp as an initialization light source, a means for rotating the recording medium, a means for condensing the initialization beam on the recording film, and a recording medium for the initialization beam. Means for moving the upper position, means for optimally controlling the power level and irradiation time of the initialization beam, means for shaping the beam emitted from the halogen lamp so that the spot shape becomes an elliptical or fan-shaped spot, light It has positioning means for arranging the longitudinal direction of the spot in a direction substantially perpendicular to the recording track direction, and means for controlling the mutual relationship between the rotation or movement of the recording medium and the radial movement of the energy beam of the recording medium. .

As described above, using a high-output halogen lamp (output of about 3 kW), the beam is shaped so that the beam spot shape emitted from this halogen lamp becomes a fan shape on the recording film surface, and this light is further shaped. By irradiating the beam in a state where the longitudinal direction of the spot is substantially perpendicular to the recording track direction, a diameter of 1
One 20 mm disc can be initialized in less than 1 second with little change in the jitter of the reproduced signal due to the number of overwrites, and compared to the conventional method (initialization for each recording track on the groove and between the grooves). Was reduced to less than 1/10.

In the present invention, at least the protective layer on the substrate,
A recording medium having an optical recording film, an intermediate layer, and a reflective layer formed in this order is used. At this time, the film thickness of each layer was set within the following range.

First, if the thickness of the protective layer is thinner than 50 nm, the flow of the recording film due to overwriting tends to occur, and if it is thicker than 150 nm, the damage due to heat during recording becomes large, so that the thickness is preferably 50 nm or more and 150 nm or less. In particular, it is preferably 60 nm or more and 130 nm or less, which allows a large absorption rate with a laser for initialization.

When the film thickness of the optical recording film is 10 nm or less, a large signal level cannot be obtained, and when the film thickness is 50 nm or more, the flow of the recording film is likely to occur due to overwriting. It is preferably 12 nm or more and 40 nm or less, which has good characteristics.

If the thickness of the intermediate layer is 5 nm or less, it may be deformed at the time of overwriting or diffusion may occur between the recording film and the reflective layer, and if it is 50 nm or more, the gradual cooling structure results and the power margin of the erase ratio becomes narrow. Therefore, 5nm or more and 50n
m or less, and particularly, it is difficult for the recording film to flow.
It is preferably not less than 30 nm and not more than 30 nm.

When the film thickness of the reflective layer is 30 nm or less, the effect as a reflective layer is small, and when it is 300 nm or more, the film is easily peeled off. Therefore, the film thickness is preferably 30 nm or more and 300 nm or less, and particularly 50 nm or more 20 which has a large thermal and mechanical effect.
0 nm or less is preferable. The recording film used is a crystal-amorphous phase change optical recording film capable of high-speed crystallization or an amorphous-
A recording film utilizing a change between amorphous and a crystal-crystal phase change recording film such as a change in crystal system or a change in crystal grain size are preferable, but other recording films may be used. In particular, a recording film using a phase change such as a Ge-Sb-Te recording film or an Ag-In-Sb-Te recording film may be used.

A recording film in which a high melting point material such as Cr ₂ Te ₃ which has a higher melting point than the main component material is added to the recording film,
It is preferable to use a recording medium having two reflective layers as in the present embodiment because it is possible to suppress a change in the recording film thickness due to the flow of the recording film. Here, when the number of the reflective layers is two, the thickness of the first layer is preferably from 20 nm to 300 nm, and particularly preferably from 50 nm to 100 nm.
When the thickness of the second layer is 30 nm or less, it is difficult to suppress the change in the thickness of the recording film due to the flow of the recording film.
If it exceeds m, a quenching structure is formed, and the remaining portion is likely to be left out. Therefore, the thickness is preferably 30 nm or more and 400 nm or less, and particularly preferably 50 nm or more and 300 nm or less so that flow of the recording film hardly occurs due to overwriting.

It is preferable that the initialization be performed after the two discs are bonded together as in the present embodiment because it can be performed more reliably, but at least after the protective coating is applied, the recording film is less damaged. Good.

In this embodiment, the initialization is carried out after the certifying (defect inspection by reading) of the disk, but the same effect can be obtained if it is carried out at the same time as the certifying of the disk or before the certifying.

The above description is about the method of manufacturing an information recording medium (the stage in which the manufacturer manufactures the recording medium) in which information can be rewritten by irradiation of the energy beam. However, the recording medium of the present invention is actually used. The above-mentioned effect can be obtained even in the case of performing the trial writing (related to the preprocessing method) in the apparatus for recording / reproducing information.

[0054]

According to the present invention, an energy beam of a high-output halogen lamp or the like is used for initialization, and the beam is shaped so that the beam spot shape becomes elliptical, rectangular, or fan-shaped on the recording film surface, Further, by irradiating the beam in a state in which the longitudinal direction of the light spot is arranged substantially perpendicular to the recording track direction, it is possible to reduce the characteristic change due to the difference in the number of overwrites.

[Brief description of drawings]

FIG. 1 is a sectional view of a disk used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an initialization method according to an embodiment of the present invention.

FIG. 3 is a ternary recording waveform diagram.

FIG. 4 is an explanatory diagram of dependency of jitter on the number of overwrites.

[Explanation of symbols]

9 ... Halogen lamp, 10 ... Elliptical spot, 11 ... Reflector, 12 ... Lens, 13 ... Motor, 14 ... Disk.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hiroshi Toyama 1-280 Higashi Koikeku, Kokubunji, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Inventor, Yasuhide Matsumura 1-280 Higashi Koikeku, Kokubunji, Tokyo Hitachi, Ltd. Central Research Laboratory (72) Inventor Akemi Hirotsune 1-280, Higashi Koikekubo, Kokubunji, Tokyo Hitachi Co., Ltd. Central Research Laboratory (72) Inventor Shin Miyamoto 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Prefecture Hitachi, Ltd. Visual Media Division

Claims (23)

[Claims] 1. An optical recording medium capable of recording information by irradiation with an energy beam, wherein the maximum width of crystal grains after initialization is 0.1 μm or more. 2. The information recording medium according to claim 1, wherein the width of the large crystal grains is wider than the width of the recording track. 3. A recording medium for information according to claim 1, wherein the beam emitted from the initialization light source is irradiated on the recording medium in a pulsed manner. 4. The edge of one side of the crystal grain region at the boundary between the initialized region and the non-initialized region has a shape in which a large number of arcs are gathered. Information recording medium. 5. The initialization beam according to claim 1, wherein at least a part of the recording film is emitted from an incoherent initialization light source capable of continuous light emission, and the maximum width of the beam spot on the disk is larger than the recording track pitch. A recording medium for information that has been crystallized by irradiation with. 6. The information recording medium according to claim 1, which has undergone a melting process by irradiation with an initialization beam. 7. A protective layer, an optical recording film, an intermediate layer, and a reflective layer on a substrate, wherein the protective layer has a thickness of 5
A recording medium for information having a thickness of 0 nm to 150 nm. 8. The optical recording film according to claim 1, comprising a protective layer, an optical recording film, an intermediate layer and a reflective layer on the substrate, and the film thickness of the optical recording film is
An information recording medium having a thickness of 10 nm or more and 50 nm or less. 9. The substrate according to claim 1, comprising a protective layer, an optical recording film, an intermediate layer and a reflective layer on the substrate, and the thickness of the intermediate layer is 5 n.
A recording medium of information having a size of not less than m and not more than 50 nm. 10. A protective layer, an optical recording film, an intermediate layer, and a reflective layer on a substrate, wherein the reflective layer has a film thickness of 3
An information recording medium having a thickness of 0 nm to 400 nm. 11. The substrate according to claim 1, further comprising a protective layer, an optical recording film, an intermediate layer, a first reflective layer, and a second reflective layer on the substrate, the second reflective layer having a thickness of 20 nm or more and 400 nm or less. A recording medium for certain information. 12. A method for initializing an information recording medium capable of initially recording an optical recording medium capable of recording information by irradiation of an energy beam, wherein an incoherent initialization light source capable of continuous light emission is used. A method of initializing a recording medium for information, comprising the step of irradiating an initializing beam emitted and having a maximum width of a beam spot on the disc larger than a recording track pitch. 13. The method for initializing an information recording medium according to claim 12, wherein the initialization light source is a light source that emits light by heating a filament such as a halogen lamp. 14. The method for initializing an information recording medium according to claim 12, wherein the initialization light source is a discharge tube such as a xenon lamp or a mercury lamp. 15. The method for initializing an information recording medium according to claim 12, wherein the recording film is initialized under the condition that the recording film is recrystallized during cooling after the recording film is melted. 16. The beam forming method according to claim 12, wherein the beam spot shape emitted from the initialization light source is elliptical, rectangular or fan-shaped on the surface of the recording film.
An information recording medium initialization method, comprising the step of performing initialization while rotating the recording medium in a state in which the major axis direction of the beam spot is arranged substantially perpendicular to the recording track direction. 17. An information recording medium initialization method according to claim 12, further comprising the step of irradiating the recording medium with a beam emitted from said initialization light source in a pulsed manner. 18. The linear velocity of the recording medium at initialization, v, the half-value width of the initialization beam in the recording track direction, and the pulse irradiation frequency of the initialization beam on the recording medium, f. Then, the method of initializing the information recording medium, which is initialized under the condition that f ≧ (v / x) is satisfied. 19. The irradiation according to claim 12, wherein the irradiation is performed at a power lower than the melting point and at a temperature at which crystallization is easy,
Next, a method of initializing a recording medium for information, in which irradiation is performed with a power that melts at least a part of the recording film. 20. The irradiation according to claim 12, wherein irradiation is first performed with a power that melts at least a part of the recording film, and then,
A method for initializing an information recording medium in which irradiation is performed with a power which is lower than the melting point of recording and has a temperature at which crystallization easily occurs. 21. An incoherent initialization light source capable of continuous light emission in an information recording medium initializing device for initially making an optical recording medium capable of recording information by irradiation of an energy beam, The information recording means includes means for rotating or moving the recording medium, means for converging the light beam for initialization on the recording film, or means for passing only a part of the light beam on the recording film. Recording medium initialization device. 22. The information recording medium initialization device according to claim 21, further comprising means for controlling a power level and an irradiation time of the initialization light beam to temporarily melt at least a part of a recording film. 23. The method according to claim 21, wherein
Each of the means is a light source for initialization, and means for condensing or limiting so that the shape of the initialization beam spot on the surface of the recording film is an ellipse, a rectangle, or a part of a fan shape.
Rotation or movement means of the recording medium, further means for controlling the mutual relationship between the rotation or movement and the movement of the initialization beam in the radial direction of the recording medium, the longitudinal direction of the beam spot with respect to the recording track direction. And an information recording medium initialization device including a positioning means arranged substantially at right angles.