JP3605902B2 - Method for manufacturing multilayer optical recording medium - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a multilayer optical recording medium.
[0002]
[Prior art]
As an optical recording medium for recording various kinds of information for audio, video, and the like, a ROM (Read Only Memory) type such as an optical disk, an optical card, a magneto-optical disk, and a phase-change optical recording medium for recording or reproducing by light irradiation; There are optical recording media such as write-once type and rewritable type. For example, in a ROM type such as a compact disk, fine irregularities such as phase pits, pre-grooves and the like for recording data information, tracking servo signals, and the like are recorded on an information recording layer thereof. Fine irregularities such as pregrooves are also formed on a magneto-optical medium such as a write-once type, a rewritable type, or a magneto-optical medium based on phase change.
[0003]
On the other hand, due to a demand for a large capacity of information recording, the practical development of a multilayer optical recording medium in which two or more information recording layers are formed is remarkable.
[0004]
FIG. 1 is a schematic cross-sectional view of an optical recording medium having a two-layer structure in which first and second information recording layers 13 and 14 are laminated on a transparent substrate 1 via a transparent intermediate film 23.
[0005]
The first information recording layer 13 has first fine irregularities 21 formed by, for example, injection molding of a transparent resin such as polycarbonate together with the substrate 1 and a semi-transparent film 15 made of, for example, SiN. The information recording layer 14 has a second fine unevenness 22 formed thereon, and a reflective film 16 such as an Al vapor-deposited film formed thereon. On this second information recording layer 14, a protective film 6 made of a photocurable resin or the like is formed.
[0006]
Reading of information from the first information recording layer 13 and the second information recording layer 14 with respect to this optical recording medium is performed so that the drive device can be simplified, and the first and second information recording layers are read. In order to be able to continuously record or read the data 13 and 14, the recording and reading can be performed by light irradiation from the same side of the optical recording medium, that is, the substrate 1, by a set of optical heads. desired. The recording or reading of the first and second information recording layers 13 and 14 from the same side is performed by focusing the irradiation light L from the optical head onto the first information recording layer 13 as shown by a solid line in FIG. Then, the recording and reproduction are performed, and the irradiation light L from the optical head is focused on the second information recording layer 14 as shown by a broken line in FIG. Recording and playback. According to this method, in order to prevent interference between the information recording layers 13 and 14 in reading or reproducing, the thickness of the transparent intermediate film 23 between these information recording layers should be 30 to 60 μm. For example, it is necessary to select a large thickness of about 40 μm.
[0007]
[Problems to be solved by the invention]
As a method for obtaining a multilayer optical recording medium in which, for example, the first and second information recording layers 13 and 14 are laminated, the first information recording layer 13 is formed, for example, by forming the first fine irregularities 21 with a polycarbonate resin or the like. Is formed by injection molding together with the substrate 1 made of the transparent resin described above, and a semi-transparent film 15 is formed thereon by adhesion.
[0008]
Then, on the first information recording layer 13, the transparent intermediate film 23 and the second fine irregularities 22 of the second information recording layer 14 are formed. As a method for forming the transparent intermediate film 23 and the second fine irregularities 22, a photocurable resin film, a so-called sheet-like dry photopolymer film, is interposed, and is formed thereon by, for example, a so-called 2P method (Photopolymerization method).
[0009]
The method for forming the fine irregularities of the transparent intermediate film 23 and the second information recording layer 14 is as follows. First, as shown in FIG. 3, for example, as described above, the first information recording layer 13 is formed by injection molding. On the substrate 1 on which the unevenness 21 is formed and on which the translucent film 15 is formed (not shown), the photocurable resin film 30 is pressed by a roller 19 under heating, and the first Buried in the fine irregularities 21 and ensure close contact. Further, the photocurable resin 3 is applied on the photocurable resin film 30.
[0010]
Thereafter, as shown in FIG. 5, the substrate 1 is illuminated on the stamper 8 on which the fine unevenness 8s of the transfer pattern of the fine unevenness to be formed on the target second information recording layer is formed, as shown in FIG. The side on which the curable resin 3 is applied is brought into contact with the side of the stamper 8 on which the fine irregularities 8s are formed. In this state, for example, a cylindrical pressing roller 9 is rolled on the substrate 1 by applying a constant load from above the substrate 1 disposed on the stamper 8. By doing so, the photocurable resin 3 interposed between the substrate 1 and the stamper 8 is pressed and spreads along the plate surfaces of the substrate 1 and the stamper 8. Thereafter, as shown in FIG. 6, the photocurable resin 3 is cured by irradiating ultraviolet rays from a rear surface of the substrate 1 with an ultraviolet lamp (UV lamp) 10. Thereafter, as shown in FIG. 7, the substrate 1 is peeled off from the stamper 8 together with the photocurable resin 3. By doing so, the fine unevenness 22 of the second information recording layer 14 is formed on one surface of the substrate 1 by the photocurable resin 3. A reflective film 16 shown in FIG. 1 is formed on this disk, a second information recording layer 14 is formed, and a protective film 6 is applied thereon to obtain a multilayer optical recording medium (optical disk).
[0011]
As shown in FIG. 2, in the multilayer optical recording medium having this configuration, the transparent intermediate film 23 is composed of the photocurable resin film 30 and the photocurable resin 3 forming the second fine irregularities 22.
[0012]
On the substrate 1 on which the fine irregularities 21 forming the first information recording layer 13 are formed by injection molding as described above, the photocurable resin film 30 is heated by the rollers 19 as shown in FIG. At the time of pressure bonding, deformation such as tangential skew or radial skew has occurred on the substrate 1.
[0013]
Conventionally, no compensation has been made for the deformation of the substrate 1 caused by the pressing by the roller 19 in the manufacturing stage.
[0014]
The deformation of the substrate 1 (such as tangential skew) is caused by various causes such as shrinkage of the photocurable resin film 30 when the photocurable resin film 30 is pressed against the substrate 1 under heating. Photocuring of the photocurable resin film 30 is performed while the substrate 1 is deformed, and then a second information recording layer is formed to produce a multilayer optical recording medium. Irradiation of light causes the occurrence of an error when reading information due to fine irregularities by interference of the irradiation laser light.
[0015]
In the present invention, it is possible to effectively reduce the deformation of the substrate 1 so as to obtain a multilayer optical recording medium having excellent optical characteristics.
[0016]
[Means for Solving the Problems]
The method for manufacturing a multilayer optical recording medium according to the present invention is a method for manufacturing a multilayer optical recording medium comprising at least a first information recording layer and a second information recording layer laminated on each other. A step of laminating the photocurable resin film on the side having the information recording layer of the above, pressing and laminating by pressing with a roller under heating, and then exposing and curing the photocurable resin film, In the process, a bending means for forcibly bending the substrate in a direction for compensating (correcting) deformation of the substrate caused by pressure bonding by a roller or the like is arranged.
[0017]
As described above, in the present invention, the photocurable resin film is stacked on the surface of the substrate on the side having the first information recording layer, and the film is pressed and laminated with a roller under heating. In the step of exposing and curing the substrate, the substrate is forcibly bent in a direction for compensating (correcting) the deformation caused by the pressing of the substrate by a roller or the like, so that the deformation generated in the substrate during the heat-pressing of the photocurable resin film is reduced. It can be greatly reduced.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
A specific embodiment of the present invention will be described.
In the following, a case where a disk-shaped, so-called disk-shaped optical disk is applied will be described. Needless to say, the present invention can be applied to various optical recording media having fine irregularities such as a sheet in the information recording layer.
[0019]
In this example, as shown in FIG. 1, for example, a data recording pit or a first groove such as a pre-groove is formed on one main surface of the substrate 1 by injection molding of a light transmitting resin such as polycarbonate. The first information recording layer 13 is formed by forming the fine irregularities 21 on which the translucent film 15 is formed. On the first information recording layer 13, second fine irregularities 22 such as data recording pits and / or pre-grooves are formed by a 2P method via a photocurable resin film 30, A second information recording layer 14 is formed by applying a reflective film 16 such as an Al vapor-deposited film. In this case, an optical recording medium, for example, an optical disk, in which a protective film 6 made of, for example, a photocurable resin is applied on the second information recording layer 14, is obtained.
[0020]
In this case, the transparent intermediate film 23 mainly composed of the photocurable resin film 30 is formed between the first and second information recording layers.
[0021]
In this example, as shown in FIG. 3, for example, a thickness of 50 μm is formed on the substrate 1 (not shown) on which the fine irregularities 21 for forming the first information recording layer 13 are formed by injection molding as described above. The photocurable resin film 30 is pressed by a roller 19 under heating at, for example, 90 ° C. to 100 ° C. At this time, the propeller-like deformation tends to occur on the substrate 1 in the traveling direction of the roller 19 and is observed as tangential skew. After the photocurable resin film 30 is pressed by the rollers 19 in this manner, the film protruding from the outer periphery of the substrate 1 is cut off, and the photocurable resin film 30 is laminated only on the substrate 1. The curable resin film 30 is exposed and cured.
[0022]
In the present invention, means for forcibly bending the substrate 1 in a direction for compensating (correcting) the deformation of the substrate 1 that has occurred earlier during the exposure and curing of the photocurable resin film 30 on the substrate 1. Is provided, the deformation of the substrate 1 is effectively reduced.
[0023]
Next, the bending means for compensating the deformation of the substrate 1 will be described with reference to the schematic sectional view of FIG.
[0024]
In this example, a horizontal support 33 for supporting the substrate 1 is provided, on which a holder 34 for holding at least a part of the outer periphery of the substrate 1 toward the horizontal support 33 is provided, and the support holder 31 is formed. I do.
[0025]
On the horizontal support 33, a spacer 32 is provided at the center of the horizontal support 33 to compensate (correct) the deformation of the substrate 1, which is a so-called counterbalance. It is desirable that the spacer 32 can be integrated with the horizontal support 33 and that the height can be adjusted.
[0026]
The substrate 1 is arranged on the horizontal support 33 via the spacer 32 such that the spacer 32 is located at the center of the furniture substrate 1, and is pressed down from above the outer peripheral portion by the holder 34 and fixed.
[0027]
At this time, the substrate 1 is forcibly bent in a direction for compensating (correcting) the deformation generated when the photocurable resin film 30 is pressed by the roller 19, that is, for counterbalancing the deformation. , Are fixed to the support holder 31.
[0028]
Thereafter, the photocurable resin film 30 is exposed and cured in this state.
[0029]
According to the above-described method of the present invention, the deformation occurring in the conventional substrate 1, for example, the tangential skew remaining about ± 0.2 (deg) is suppressed to about ± 0.05 (deg). Was completed. The radial skew was also suppressed to about ± 0.05 (deg). Thus, the deformation of the substrate 1 was effectively reduced.
[0030]
As described above, according to the present invention, since the deformation of the substrate 1 can be significantly reduced, the thickness of the intermediate layer between the information recording layers formed by the 2P method can be made extremely uniform.
[0031]
After exposing and curing the photocurable resin film 30 in this manner, a second information recording layer is formed by the 2P method.
[0032]
On the other hand, as shown in FIG. 5, a stamper 8 made of a magnetic metal such as nickel, for example, having transferred fine unevenness 8s for forming fine unevenness of the second information recording layer 14 is prepared.
[0033]
As shown in FIG. 8, the stamper 8 is disposed on a horizontal base 35 having, for example, a permanent magnet or an electromagnet (not shown). The stamper 8 is magnetically attracted and held on the horizontal base 35 with a sufficient flatness.
[0034]
Then, the substrate 1 on which the photocurable resin 3 is applied is matched with the stamper 8 by interposing the photocurable resin 3 between the substrate 1 and the stamper 8.
[0035]
In this state, for example, the columnar roller 9 is rolled on the substrate 1 by applying a constant load from above the substrate 1 disposed on the stamper 8.
[0036]
In this way, the fine irregularities 8s of the stamper 8 are transferred to the photocurable resin 3 which is spread between the substrate 1 and the stamper 8 and pressed between them, thereby forming the second information recording layer 14. Fine irregularities are formed.
[0037]
Thereafter, the photocurable resin 3 pressed between the substrate 1 and the stamper 8 is irradiated with ultraviolet light from the back of the transparent substrate 1 by an ultraviolet (UV) lamp 10 as shown in FIG. Photopolymerization of the curable resin 3, that is, photocuring is performed.
[0038]
Thereafter, as shown in FIG. 7, the substrate 1 is peeled off from the stamper 8 together with the photocurable resin 3. As described above with reference to FIG. 1, on the first information recording layer 13 formed by injection molding, the photocurable resin 3, in this example, an ultraviolet curable resin is used to form phase pits, pregrooves, and the like. The second fine irregularities 22 are formed. Then, on the surface of the photocurable resin 3 on which the second fine irregularities 22 are formed, a reflective film 16 made of a metal, for example, an Al deposited film is applied to form the second information recording layer 14. On the second information recording layer 14, at the same time, a protective film 6 made of, for example, a photocurable resin, for example, an ultraviolet curable resin is applied to form a target optical recording medium, for example, an optical disk.
[0039]
As described above, since the deformation of the substrate 1 can be effectively reduced, a multilayer optical recording medium in which an information recording layer in which the thickness of the transparent intermediate film 23 between the information recording layers is large is formed by a simple method. The film thickness of the transparent intermediate film 23 can be formed with extremely good uniformity, whereby a multilayer optical recording medium having excellent optical recording / reproducing characteristics and small errors, that is, excellent optical characteristics, can be obtained.
[0040]
In the above-described example, a case was described in which a multilayer optical recording medium in which two information recording layers were formed was described. However, the present invention is not limited to this, and three or more information recording layers were stacked. It goes without saying that the present invention can also be used when obtaining an optical recording medium.
[0041]
The above-described example is a case where the second fine irregularities 22 forming the second information recording layer 14 are formed by the 2P method, but the second information recording layer is formed on the photocurable resin film 30 itself by the stamper 8. The second fine irregularities 22 that form the sub-region 14 may be formed.
[0042]
In the above-described example, the case where the substrate 1 is a disk is mainly described, but the present invention can be applied to various structures such as a card.
[0043]
Further, as described above, the method of the present invention is an optical disk, that is, a method in which fine irregularities include data information. However, the present invention is not limited to this case. As described above, the present invention can also be applied to a case where an optical recording medium having an information recording layer having fine grooves and pits for pre-grooves and pits, for example, for tracking and adores, is used. A layer in which a magneto-optical material and a phase change material are formed can be used.
[0044]
【The invention's effect】
As described above, according to the method of the present invention, in the production of the optical recording medium, the deformation of the substrate can be effectively reduced, so that the information recording layer in which the thickness of the transparent intermediate film between the information recording layers is large is increased. In a multilayer optical recording medium in which a layer is formed, the thickness of this transparent intermediate film can be formed with extremely uniform uniformity by a simple method, and thereby, the optical recording / reproducing characteristics are excellent, and the error occurrence is small, that is, the optical characteristics are improved. An excellent multilayer optical recording medium can be obtained, the occurrence rate of defective products can be sufficiently reduced, and the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of a multilayer optical recording medium.
FIG. 2 is a schematic sectional view of a multilayer optical recording medium.
FIG. 3 is a schematic cross-sectional view of one step for explaining the conventional method and the method of the present invention.
FIG. 4 is a schematic cross-sectional view of one step for explaining the method of the present invention.
FIG. 5 is a perspective view of one step for explanation of a conventional method and the method of the present invention.
FIG. 6 is a perspective view of one step for explaining the conventional method and the method of the present invention.
FIG. 7 is a perspective view of one step for explanation of a conventional method and the method of the present invention.
FIG. 8 is a perspective view of one step for explaining the conventional method and the method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 3 Photocurable resin 6 Protective film 8 Stamper 8s Fine unevenness 9 Roller 10 UV lamp 13 First information recording layer 14 Second information recording layer 15 Translucent film 16 Reflective film 19 Roller 23 Transparent intermediate film 30 Light curing Resin film 31 Support holder 32 Spacer 33 Horizontal support 34 Holder 35 Horizontal base

Claims (1)

In a method for manufacturing a multilayer optical recording medium in which at least first and second information recording layers are laminated,
A step of superimposing a photocurable resin film on a surface of the substrate having the first information recording layer, the surface having the first information recording layer, and pressing and laminating with a roller under heating;
Thereafter and a step of exposing curing the photocurable resin film, in said exposure process, the substrate to forcibly flex the substrate in a direction that compensates the thus caused deformation to the roller crimp flexing A method for producing a multilayer optical recording medium, characterized by including means.

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