JP4104273B2 - Initial crystallization apparatus for information recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a phase change optical disk initial crystallizing apparatus for performing initialization by crystallizing a recording layer of a phase change recording optical disk.
[0002]
[Prior art]
In an optical information recording medium (disk) using a phase change material, the recording direction changes from crystal to amorphous. Therefore, the recording layer is converted to a crystalline state in advance as a premise for recording. This is called initialization or initial crystallization, and crystallization is generally performed by sequentially irradiating a recording layer of a disk with a high-power laser beam. In the case of this method, initialization itself takes time, and there is a disadvantage that productivity is not good.
[0003]
In order to avoid this drawback, a method of performing initialization in a short time by crystallizing the recording layer at once using a high-power flash lamp has been proposed in Japanese Patent Laid-Open No. 63-261553. Yes. However, in the method using a flash lamp, it is difficult to completely crystallize as compared with the method of initializing using the laser beam described above, and energy is given to make the crystallization state of the recording layer uniform. It has been experimentally found to be very difficult.
[0004]
In order to avoid these problems, as disclosed in JP-A-08-153343, a method for precisely controlling the output has been proposed, but in order to perform uniform crystallization, the apparatus becomes large-scale, When uniformity is required, there is a problem that initialization takes time. Furthermore, if crystallization is attempted in a short time, as pointed out in Japanese Patent Laid-Open No. 08-153343, the substrate is deformed and the recording layer is broken due to cracks. This is noticeable when a thin substrate with a thickness of 0.6 mm, such as DVD, is used, and how to prevent the substrate from being deformed is recognized as an important issue. Further, the disk initialized in Japanese Patent Laid-Open No. 08-153343 has a protective ultraviolet curable resin (˜20 μm) applied to the reflective layer surface. The DVD is completed by bonding two discs each having a thickness of 0.6 mm with a UV curable resin for bonding (about 20 to 50 μm). The function of the protective UV curable resin is the UV for bonding. It is also possible to have a cured resin. That is, in Japanese Patent Application Laid-Open No. 08-153343, the process of applying and curing the protective ultraviolet curable resin is useless.
[0005]
On the other hand, a method for initializing with small energy is proposed in Japanese Patent Laid-Open No. 05-342629. In this method, a layer for promoting crystallization (crystallization promoting layer) is provided for the recording layer, and initialization is performed with small energy. The specific method of initialization is limited to performing the initialization step after bonding, and does not refer to a specific method and apparatus regarding the initialization method.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to solve the problems of the prior art as described above, and in particular, it is an object of the present invention to provide a crystallization apparatus that efficiently initializes an information recording medium in a short time.
Furthermore, the present invention provides an initial crystallization apparatus that is particularly effective when a DVD substrate that has been attracting attention in recent years is as thin as 0.6 mm.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided a recording layer mainly composed of Ag, In, Sb, Te, which constitutes a phase change between a crystalline layer and an amorphous layer on a light-transmitting substrate, and at least a part of the recording layer. The initial crystal of the information recording medium in which the information recording medium provided with the crystallization promoting layer made of Bi or its compound in contact with the recording layer is irradiated with flash light from the side facing the recording layer, and the recording layer is collectively crystallized. And a porous plastic sheet having a thickness of 50 μm or more and a porosity of 10% or more, the holding table for holding the information recording medium , and the plastic The information recording medium placed on a sheet made of a sheet, and a pump for sucking the entire surface of the information recording medium from the lower part of the holding table.
[0011]
The invention of claim 2 is characterized in that, in any of the inventions of claim 1 , the melting point of the porous plastic sheet is 70 ° C. or higher.
[0012]
The invention of claim 3 is characterized in that, in the invention of claim 1 or 2 , the pore diameter on the surface of the porous plastic sheet is 500 μm or less.
[0013]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the holding table is provided with a temperature measuring device.
[0014]
According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the holding table is provided with a temperature adjusting mechanism.
[0015]
The invention of claim 6 is characterized in that, in the invention of claim 5 , a heater is used as the temperature adjusting mechanism.
[0016]
The invention of claim 7 is characterized in that, in the invention of claim 5 , as the temperature adjusting mechanism, a liquid medium such as water or oil and a temperature controller for controlling the temperature of the liquid medium are provided. .
[0017]
The invention of claim 8 is characterized in that, in the invention of any one of claims 1 to 7 , the distance between the flash light and the holding table is variable.
[0018]
The invention of claim 9 is characterized in that, in the invention of any one of claims 1 to 8 , a filter for blocking light of an arbitrary wavelength is provided between the flash light and the holding table.
[0019]
The invention of claim 1 0, in the invention of any one of claims 1 to 9, in which said holding table is characterized in that it is rotatable.
[0020]
The invention of claim 1 1, and characterized in that in any one of the claims 1 to 1 0, equipped with a device for applying a UV-curable resin on a recording layer and a surface facing the light transmissive substrate It is a thing.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view for explaining the configuration of an information recording medium (disc) to which the present invention is applied. The information recording medium 17 is provided on one side of a disc-shaped polycarbonate (light-transmitting substrate) 11 on a lower side. Dielectric layer (50 to 200 nm) 12, crystallization promoting layer (0.1 to 5 nm) 13, recording layer (10 to 20 nm) 14, upper dielectric layer (10 to 30 nm) 15, and reflective layer (80 to 200 nm) 16. The thickness of each layer is not particularly limited.
Although the disk shape is taken as an example of the light transmissive substrate 11, the present invention is not limited to this, and there is no problem even if it is a card shape or a sheet shape.
Further, although polycarbonate is used for the light-transmitting substrate 11, the present invention is not limited to this, and there is no problem as long as it is a material that can simply be read and written by laser such as acrylic resin and polyolefin resin. Inorganic materials may be used. The lower and upper dielectric layers 12 and 15 are made of ZnS—SiO ₂ , but are not limited to this. For example, oxides such as ZrO, TaO, GeO, and TiO, nitrides such as ZrN, TiN, and SiN, It is also possible to use carbides such as SiC, TiC, ZrC, NbC, MoC, and Mo ₂ C, and fluorides such as CaF.
[0022]
The crystallization method of the present invention is intended for a recording thin film in which the constituent elements of the phase change material are mainly Ag, In, Sb, and Te.
The crystallization promoting layer is also intended for a crystallization promoting layer made of Bi or a compound thereof. The combination of the recording layer AgInSbTe + crystallization promoting layer Bi or a compound thereof can achieve the recording layer initialization relatively easily. Therefore, the initialization energy is small as compared with the sequential initialization by the conventional laser beam like flash light, In addition, the entire recording layer can be uniformly crystallized even with non-uniform energy irradiation.
Although an aluminum alloy is used for the reflective layer, the present invention is not limited to this. An alloy based on Ag, Au, Pt, Ni, Cr, or the like has no problem.
[0023]
Compared with the configuration of JP-A-8-153343, the present invention is characterized in that there is a crystallization promoting layer and an ultraviolet curable resin is not applied on the upper part of the reflective film.
[0024]
FIG. 2 is a cross-sectional view of an essential part of the initial crystallization apparatus according to the present invention, and shows a holding table 21 that holds the entire surface of the information recording medium (disk) 17. The holding table 21 includes a center pin 22 for positioning the disk 17. Holes and grooves are processed in the holding table 21 in order to adsorb the disk 17 and correct the warp. The hole diameter, groove width, and groove height are not particularly limited, and there is no problem as long as the disk can be sucked. Further, the holding table 21 is connected to a suction device (pump) (not shown) so that the disk 17 is sucked (the arrow 23 indicates the sucking direction). Further, stainless steel is used as the material of the holding base 21, but the material is not limited to this, and there is no problem with plastics and ceramics as well as metals as long as holes and grooves can be processed. Further, if porous ceramics or the like is used as the material of the holding base 21, processing of holes and grooves becomes unnecessary.
[0025]
Reference numeral 24 denotes a flash lamp. As the flash lamp 24, for example, a pulse oscillation type spiral tubular flash lamp in which xenon (Xe) gas is sealed (for example, RC740B manufactured by US XENON Co., Ltd., etc.) is used. However, the present invention is not limited to this, and there is no problem as long as there is energy intensity (or illuminance) for crystallizing the recording layer. Although different depending on the material and thickness of the recording layer or the like, in this embodiment, uniform initial crystallization was possible with a light intensity of 365 nm wavelength of 300 W / cm ² and a pulse width of 200 μsec × 9 pulses. Furthermore, when using a linear rod-shaped lamp, the holder can be rotated in order to avoid uneven curing of the ultraviolet curable resin due to uneven illumination of the lamp.
[0026]
FIG. 3 is a cross-sectional view of an essential part for explaining another embodiment of the present invention. In this embodiment, a porous plastic sheet 25 is installed on the holding base 21, and FIG. The electron micrograph is shown. 4A shows a surface SEM photograph of the porous plastic sheet 25, and FIG. 4B shows a cross-sectional SEM photograph. In this example, an ultra-high molecular weight polyethylene resin was used . For example, a map made by Nitto Denko Corporation corresponds to this. However, the material is not limited to this, and there is no problem as long as the material is simply porous and has the following conditions (1) to (4).
[0027]
(1) First, the thickness of the porous plastic sheet 25 is 50 μm or more. If it is too thin, not only handling is cumbersome, it tends to wrinkle when fixed to the holder, in the end, the quality of the bonded optical disk you deterioration.
[0028]
(2) Second, the porosity of the porous plastic sheet 25 is 10% or more. If the porosity is too low, it takes time to adsorb the disc, and the disc warped by several hundred μm cannot be corrected. Here porosity between, among FIG scanning electron ray photographic image shown in (cross-sectional SEM photograph), that defines a ratio area of the air layer other than polyethylene (Equation 1).
Porosity = (Ratio of air layer other than polyethylene / total area) × 100%
・ ・ ・ ・ ・ ・ Formula 1
[0029]
(3) Third, the melting point of the porous plastic sheet 25 is 70 ° C. or higher. Although the melting point of the porous plastic sheet of this example was about 130 to 140 ° C., it is not limited to this, and it is clear from the experimental results that there is no problem if it is 70 ° C. or higher. became. A disk molded at a mold temperature of a few hundred tens of degrees Celsius is brought into an initial crystallization process through a process such as sputtering film formation. It depends on the production tact, the heat capacity and thermal conductivity of the porous plastic sheet, and the heat capacity and thermal conductivity of the holding table, but if the melting point of the porous plastic sheet is lower than the temperature of the loaded disc, it will melt. The function cannot be performed. In addition, the temperature of the disk rises due to flash light irradiation. This temperature irradiation energy of the flash light, varies depending on the distance or the like between the disc and the lamp, the temperature of the disk that is that has been confirmed experimentally that not more than 70 ° C..
[0030]
(4) Fourth, the pore diameter of the porous plastic sheet 25 is 500 μm or less. Even if the above conditions (1) to (3) are satisfied, if the hole diameter of the air layer portion indicated by the scanning electron beam photograph (surface SEM photograph) shown in FIG. In addition to facilitating the entry of foreign matter into the air layer portion, the surface of the disk may be slightly deformed during suction. This, at the time of adsorbing the first disk, significantly varies depending setting the suction force, that has been confirmed that no problem as long as approximately 500μm or less.
[0031]
FIG. 5 is a block diagram of the main part for explaining another embodiment of the present invention. In this embodiment, a thermocouple 26 and a heater 27 are installed on the holding base 21, and they are connected to the control circuit 28. Yes. As the thermocouple 26, a K-type chromel-alumel thermocouple was used. The type of thermocouple is not particularly limited, and there is no problem with T-type Cu-constantan or the like. The control circuit 28 includes an A / D conversion board that converts the analog voltage from the thermocouple 26 into digital, and a computer. The computer is programmed in C language with functions such as feedback control for displaying and outputting the temperature of the thermocouple, controlling the heater voltage, and maintaining the temperature of the holding table at a constant temperature. In this embodiment, a computer is used. However, the present invention is not particularly limited to the computer. If there is a voltmeter that can display the temperature of the thermocouple and a transformer that can control the heater voltage, the holding table can be manually moved. It is possible to control the temperature.
[0032]
FIG. 6 is a configuration diagram of the main part for explaining another embodiment of the present invention. In this embodiment, a flow path 29 in which a liquid medium such as water or oil flows is processed in the holding base 21. Yes. In this embodiment, the channel 29 has a circular cross section and is processed on the same plane. The shape of the flow path 29 is not limited. The flow path 29 is connected to a temperature controller (not shown), and a liquid medium such as water or oil is introduced from the temperature controller in the direction of arrow A and is returned to the temperature controller from the direction of arrow B. The temperature of the medium can be varied from 0 to 150 ° C. by the temperature controller.
[0033]
FIG. 7 is a block diagram of the main part for explaining still another embodiment of the present invention. In this embodiment, the holding base 21 is connected to an air cylinder at its rotating shaft 21 ', and is indicated by an arrow C. As shown, the upper and lower positions can be arbitrarily set. The irradiation energy necessary for the initial crystallization can be changed by selecting the material and thickness of the recording layer including the crystal accelerating layer and the upper and lower protective layers, and the distance between the holder and the lamp. Further, a filter 30 that absorbs an arbitrary wavelength is provided between the flash lamp 24 and the holding table 21. The filter 30 is removable so that the type and thickness thereof can be easily changed. The filter 30 has a function of blocking light other than the absorption wavelength of the recording layer. That is, it is for efficiently transferring the recording layer to a polycrystal, and is also involved in the design of each layer. Further, the rotating shaft 21 'is connected to the motor so that the holding base 21 can rotate. This rotation is for eliminating unevenness in the illuminance of the lamp, and a variable device is provided that can change the motor speed. .
[0034]
FIGS. 8 to 10 are main part configuration diagrams for explaining still another embodiment of the present invention, FIG. 8 is a schematic configuration diagram of an initial crystallization apparatus according to the present invention, and FIG. 9 is an IX-IX of FIG. FIG. 10 is a cross-sectional view taken along the line X-X of FIG. 8. In this embodiment, a dispenser 32 for applying an ultraviolet curable resin 31 on the side facing the recording layer on the disk 17 and the disk 17 are held. The rotating table 33 that rotates while rotating, the cover 34 that prevents the ultraviolet curable resin 31 from scattering, the transport arm 35 that carries the disk 17 coated with the ultraviolet curable resin 31 to the initial crystallization device, and the disk 17 are adsorbed. A pad 36 and an initial crystallization device 37 are included.
[0035]
If scratches or dust is present on the surface facing the recording layer, that is, the disk reading surface, reading or writing errors are likely to occur. For the purpose of protecting this reading surface, commercially available information recording media such as MO, CD-RW, DVD-RAM, DVD-RW and DVD + RW are coated with acrylic UV curable resin of several to several tens of μm. . In this example, acrylic ultraviolet curable resin was used, but the material and film thickness are not particularly limited, the surface resistance is lower than that of polycarbonate, and the surface resistance value is retained even after storage at high temperature and high humidity. There is no problem as long as it is relatively hard. As shown in FIG. 9, in this example, after applying 1 g of an acrylic ultraviolet curable resin 31 having a surface resistance value of 3 to 4 × 10 ¹¹ Ω, pencil hardness (JIS K5400) and F property, × 10 ³ r. p. m. Then, the disk 17 is rotated, the UV curable resin 31 is shaken off, and the thickness is set to 2 to 4 μm.
[0036]
Next, the disk 17 coated with the ultraviolet curable resin 31 is sucked by the suction pad 36 and transported to the initial crystallization device 37 by the transport arm 35. The initial crystallization device 37 is mainly composed of four holding bases 21 on the index table 38 and the flash lamp 24. The index table 38 is rotated by 90 °, and each holding table 21 is configured to rotate up and down and rotate when moved below the flash lamp 24 (the same configuration as in the fifth embodiment). The holding table 21 of the initial crystallization device 37 is provided with a reflecting plate 39 in order to efficiently cure the ultraviolet curable resin 31 protruding from the end face of the disk 17. The reflecting plate 39 of this embodiment is made of polished stainless steel, which is the material of the holding table 21, but is not limited to this, and there is no problem with a reflecting plate such as a mirror. It is only necessary that the end face of the disk can be efficiently irradiated with wavelengths in the ultraviolet region. As another method, if the ultraviolet curable resin 31 protruding from the end face of the disk 17 is removed by a blade such as rubber, a reflector as in this embodiment is not necessary.
[0037]
When the flash lamp 24 is irradiated onto the disk 17 coated with the ultraviolet curable resin 31 in the initial crystallization device 37, the ultraviolet curable resin 37 can be cured simultaneously with the crystallization of the recording layer.
[0038]
【The invention's effect】
According to initial crystallization device operations and effects according to claim 1 corresponding to 請 Motomeko 1, since it initialize the entire surface of the disk in a moment by a flash lamp, is advantageous in tact shortening of the initial crystallization time (information recording medium Cost is less). Further, even a substrate with a large warp can be initialized uniformly because the holding table adsorbs the entire disk surface. Further, since the entire surface of the disk is adsorbed, it is possible to prevent cracking and peeling of the reflective layer. Furthermore, since the crystallization promoting layer is provided, initialization can be performed with low energy and in a short time (within 3 seconds). Furthermore, since a protective ultraviolet curable resin is not required on the reflective layer surface side, an information recording medium in which two discs having a thickness of 0.6 mm such as a DVD are bonded together can be manufactured at low cost. . Furthermore, since the porous plastic sheet (elastic body) is provided between the reflective layer and the holding table, the reflective layer and the polycarbonate are not damaged. Furthermore, since the porous plastic sheet has a thickness of 50 μm or more, it is easy to handle and is less likely to wrinkle when fixed to a holding table. Furthermore, since the porosity of the porous plastic sheet is 10% or more, the entire surface of the disk can be reliably adsorbed.
[0042]
According to initial crystallization device operations and effects according to claim 2 corresponding to the 請 Motomeko 2, since a porous melting point of the plastic sheet is at 70 ° C. or higher, even reliably attracted with discs subjected to thermal history by various processes it can.
[0043]
According to initial crystallization device operational effects claim 3 corresponding to the 請 Motomeko 3, since the pore size of the plastic sheet of the porous property is 500μm or less, the time of adsorption, the light transmissive substrate, a reflective layer, the upper and lower dielectric There is no slight deformation of the recording layer including the body layer and the crystal promoting layer. As a result, the initial crystallization can be made uniform.
[0044]
According to initial crystallization device operational effects claims 4 to 6 corresponding to the 請 Motomeko 4-6, the temperature of the holder can be measured, the temperature of the holder can be adjusted, and maintain the temperature of the holder constant adjustment Since the mechanism is provided, not only can the initial crystallization be stably performed, but also the initial crystallization can be assisted, so that the range of conditions for the initial crystallization is widened.
[0045]
According to initial crystallization device operations and effects according to claim 7 corresponding to the 請 Motomeko 7, since the temperature of the holder portion it is possible to temperature control for keeping and constant at low temperatures, the holder with the flash lamp irradiation Temperature rise can be prevented and stable initial crystallization can be achieved.
[0046]
According to initial crystallization device operations and effects according to claim 8 which corresponds to 請 Motomeko 8, since the distance between the holder and the flash lamp is variably, easy to set conditions of initial crystallization, also condition the width spread.
[0047]
According to initial crystallization device operations and effects according to claim 9 which corresponds to 請 Motomeko 9, since the filter for blocking light of an arbitrary wavelength flashlamp between holder is provided, it can be efficiently initial crystallization In addition, since the light in the infrared region that causes the temperature rise is blocked, the temperature rise of the disk and the holding table can be prevented. As a result, the initial crystallization can be stabilized.
[0048]
According to initial crystallization device operations and effects according to claim 1 0 corresponding to 請 Motomeko 1 0, since holder is rotatable, it is possible to cover the uneven illuminance of the flash lamp. As a result, the flash lamp shape can be simplified (for example, a cylindrical shape like a fluorescent lamp), and the cost of the apparatus can be reduced.
[0049]
According to initial crystallization device operations and effects according to claim 1 1 which corresponds to 請 Motomeko 1 1, for protecting the light-transmitting substrate (polycarbonate), an ultraviolet curing resin coating device is provided, the curing of the ultraviolet curable resin Since the process and the initial crystallization process can be performed together, the manufacturing tact can be shortened.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an information recording medium (disc) to which the present invention is applied.
FIG. 2 is a sectional view of an essential part for explaining Example 1 of the initial crystallization apparatus according to the present invention.
FIG. 3 is a cross-sectional view of an essential part for explaining Example 2 of the initial crystallization apparatus according to the present invention.
4 is a view showing an SEM photograph of a plastic sheet in Example 2 shown in FIG. 3. FIG.
FIG. 5 is a cross-sectional view of an essential part for explaining Example 3 of the initial crystallization apparatus according to the present invention.
FIG. 6 is a cross-sectional view of an essential part for explaining Example 4 of the initial crystallization apparatus according to the present invention.
FIG. 7 is a cross-sectional view of an essential part for explaining Example 5 of the initial crystallization apparatus according to the present invention.
FIG. 8 is a schematic configuration diagram of an essential part for explaining Example 6 of an initial crystallization apparatus according to the present invention.
9 is a cross-sectional view taken along line IX-IX in FIG.
10 is a cross-sectional view taken along line XX in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Polycarbonate (light-transmitting substrate), 12 ... Lower dielectric layer, 13 ... Crystallization promoting layer, 14 ... Recording layer, 15 ... Upper dielectric layer, 16 ... Reflective layer, 17 ... Information recording medium (disc), DESCRIPTION OF SYMBOLS 21 ... Holding stand, 22 ... Center pin, 23 ... Adsorption direction, 24 ... Flash lamp, 25 ... Porous plastic sheet, 26 ... Thermocouple, 27 ... Heater, 28 ... Control circuit, 29 ... Flow path, 30 ... Filter 31, UV curable resin 32, dispenser 33, rotary table 34, cover 35, transfer arm 36, suction pad 37, initial crystallization apparatus, 38 index table, 39 reflector.

Claims (11)

A constituent element that causes a phase change between a crystalline layer and an amorphous layer on a light-transmitting substrate is mainly composed of a recording layer made of Ag, In, Sb, Te and Bi or a compound thereof in contact with at least a part of the recording layer. In the initial crystallization apparatus for an information recording medium, the information recording medium having the crystallization promoting layer is irradiated with flash light from the surface facing the recording layer to collectively crystallize the recording layer. A holding table for holding the medium , a porous plastic sheet which is installed on the holding table and has a thickness of 50 μm or more and a porosity of 10% or more, and placed on the plastic sheet It has been the information recording medium and an initial crystallization apparatus of the information recording medium characterized in that it comprises a pump for sucking the entire surface of the information recording medium from the lower portion of the holder. The apparatus for initial crystallization of an information recording medium according to claim 1 , wherein the porous plastic sheet has a melting point of 70 ° C or higher. The porous initial crystallization apparatus of the information recording medium according to claim 1 or 2 pore size on the plastic sheet surface, characterized in that at 500μm following. Initial crystallization apparatus of the information recording medium according to any one of claims 1 to 3, further comprising a temperature measuring device in the holder. Initial crystallization apparatus of the information recording medium according to any one of claims 1 to 4, further comprising a temperature control mechanism to the holder. The initial crystallization apparatus for an information recording medium according to claim 5 , wherein a heater is used as the temperature adjusting mechanism. 6. The information recording medium initial crystallization apparatus according to claim 5 , wherein the temperature adjusting mechanism includes a liquid medium such as water or oil, and a temperature controller for controlling the temperature of the liquid medium. The flash light and the initial crystallization apparatus of the information recording medium according to any one of claims 1 to 7 the distance between the holding table is characterized in that it is a variably. Between the holding table and the flash light, initial crystallization of the information recording medium according to any one of claims 1 to 8, further comprising a filter for blocking light of wavelengths other than the absorption wavelength of the recording layer Device. Initial crystallization apparatus of the information recording medium according to any one of claims 1 to 9, characterized in that the holder is rotatable. Information recording according to any one of claims 1 to 10, characterized by comprising a device for applying a UV-curable resin on the reading surface is a surface facing to the recording layer of the light-transmitting substrate Initial crystallization device for the medium.

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