JPH10172186A - Production of optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an optical recording medium of a high recording density by forming a light transparent layer to a uniform thickness without the occurrence of deflection in a substrate. SOLUTION: A liquid photosetting resin is uniformly applied on a stamper having the contours larger than the contours of the substrate 1 constituting the optical recording medium and is cured to form a liquid photosetting resin layer 13. The information recording layer 5 forming surface of the substrate 1 constituting the optical recording medium and the liquid photosetting resin layer 13 are stuck to each other and are then peeled from the stamper 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing an optical recording medium.

[0002]

2. Description of the Related Art As an optical recording medium for recording various information for audio, video, and the like, a ROM (Read) 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 only memory (write only) type, write-once type, and rewritable type. For example, in a ROM type such as a compact disk, phase pits, pre-grooves for recording data information, tracking servo signals, etc. are recorded on the information recording layer. Fine irregularities such as pre-grooves are also formed in a magneto-optical medium such as a write-once type, a rewritable type, or a magneto-optical medium based on a phase change.

FIG. 14 is a schematic sectional view of a conventional single-layer optical recording medium such as a CD. In this optical recording medium, fine irregularities 2 are formed simultaneously with the injection molding of a transparent substrate 1 having a thickness of 1.2 mm such as polycarbonate, and a reflective film 4 such as an Al vapor-deposited film is formed on the fine irregularities 2 by a thickness of several tens nm. Formed into
The information recording layer 5 has a configuration in which a protective film 6 made of, for example, an ultraviolet curable resin is laminated on the information recording layer 5 by several μm.

The reading of information from the information recording layer 5 to the optical recording medium is performed by, for example, irradiating a reading light L from the substrate 1 side in FIG.

On the other hand, it is necessary to increase the recording density in accordance with the increase in the amount of recorded information, thereby increasing the numerical aperture of the objective lens of the optical pickup. A needs to be as large as possible. Thus, the numerical aperture of the objective lens, N.P. When A is increased, the distance between the objective lens and the information recording layer 5 needs to be selected to be small. In this case, since the inclination tolerance of the optical recording medium decreases, the information recording layer and the light incident surface are reduced. , That is, the thickness of the light transmitting layer needs to be sufficiently small, for example, 0.5 mm or less.

As described above, in order to increase the recording density as the amount of recorded information increases, as shown in FIG. 1, a light transmitting layer 10 is formed on the information recording layer 5 with a thin and uniform thickness. It has been proposed to form

In the optical recording medium shown in FIG. 1, a substrate 1 is formed to a thickness of about 1 mm by injection molding at the same time as the transfer of the fine irregularities 2, and then a reflective film 4 of an Al vapor deposited film is formed on the fine irregularities 2. Then, the information recording layer 5 is formed, and a light transmitting layer 10 of 0.5 mm or less is formed on the information recording layer 5.

The light transmitting layer 10 in such an optical recording medium may be formed by attaching a transparent sheet having a predetermined thickness on the information recording layer 5 or by forming a liquid photocurable layer on the information recording layer 5. It can be formed by applying a resin and curing it.

[0009]

However, when the light transmitting layer 10 is formed of the above transparent sheet, there are problems in the optical properties of the transparent sheet, for example, birefringence, and the transparent sheet has a small size due to static electricity. There is also a problem in the process such as the attachment of unnecessary dust.

When the light transmitting layer 10 is formed by applying the liquid photocurable resin on the substrate 1 and then curing the liquid photocurable resin, the liquid photocurable resin is applied onto the substrate 1. Sometimes, the outermost peripheral portion becomes thicker than the inner peripheral portion due to surface tension, and when this is cured, the thickness of the light transmitting layer becomes uneven. Further, when the liquid photocurable resin is cured on the substrate 1, problems such as bending of the substrate 1 due to the curing shrinkage occur.

The present inventors have conducted intensive studies, and as a result, the thickness of the light transmitting layer 10 for reading or rewriting information on the information recording layer 5 is made uniform, and the substrate 1 is bent. We have come up with a method of forming without.

[0012]

According to the present invention, there is provided a method of manufacturing an optical recording medium, comprising the steps of: forming a liquid curable liquid on a stamper having a contour larger than a contour of a substrate constituting the optical recording medium; A resin is applied, a liquid photo-curable resin is cured to form a photo-curable resin layer, and an information recording layer forming surface of a substrate constituting an optical recording medium and a photo-curable resin layer are attached to each other to form a laminate. Then, the laminate is peeled off from the stamper to form a light transmitting layer on the substrate.

According to the present invention, a photocurable resin layer having a uniform thickness is previously formed on one principal surface of a stamper, and the photocurable resin layer is adhered to a substrate to record from the information recording layer of the optical recording medium. In order to form a light transmission layer for reading information,
This light transmitting layer could be formed thin and with a uniform thickness, and the recording density of the optical recording medium could be increased.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described. In the following, a case where the present invention is applied to a disk-shaped optical disk, that is, a disk-shaped optical disk, will be described. However, the present invention is not limited to such an optical disk and a shape. Any information can be applied as long as the information recording layer has fine irregularities such as a sheet shape and the information is reproduced or recorded by focusing light on the information recording layer.

In the present invention, for example, an optical recording medium having the structure shown in FIG. 1 is obtained. That is, the substrate 1 is formed by injection molding at the same time as the transfer of the fine irregularities 2, and then the reflective film 4 is formed on the fine irregularities 2 to form the information recording layer 5, and the optical recording layer 5 is formed on the information recording layer 5. It has a configuration in which a transmission layer 10 is formed.

[Embodiment 1] As shown in FIG. 3, a stamper 11, which has a contour larger than the contour of a substrate which finally constitutes an optical recording medium and has one smooth main surface, a so-called mirror stamper Prepare This stamper 11
Has a central hole with a thickness of, for example, 0.3 mm, a diameter of 10 mm, and an outer diameter of 19 mm.
It is composed of a 0 mm disk.

The stamper 11 is placed on a rotating base (not shown), and after applying a liquid photocurable resin 13 on the stamper 11, the stamper 11 is rotated at a high speed and stretched sufficiently.

Next, as shown in FIG. 4, the liquid photo-curable resin 13 is cured by irradiating it with, for example, ultraviolet rays, so that the photo-curable resin layer 2 has a thickness of, for example, 100 μm.
Form 3

On the other hand, by the conventional method, the substrate 1 is transferred to the fine irregularities 2 and simultaneously with the thickness of 0.1 mm by injection molding.
A reflective film 4 of an Al vapor deposited film is formed on the fine irregularities 2 to form an information recording layer 5.

Next, as shown in FIG. 5, the surface of the substrate 1 obtained as described above, on which the information recording layer 5 is to be formed, and the photocurable resin layer 23 are bonded with the photocurable resin 3 for bonding. And the roller 31 is rolled on the substrate 1 and pressed,
For example, the photocurable resin 3 is cured by irradiating ultraviolet rays. Here, a layer formed by laminating the substrate 1, the information recording layer 5, and the photocurable resin layer 23 shown in FIG.

Next, as shown in FIG. 6, the laminate 30 obtained as described above is peeled from the stamper 11. At this time, the photocurable resin layer 23 is separated from the stamper 11 in accordance with the outer diameter of the substrate 1, for example, by molding and matching with the substrate 1. In this way, as shown in FIG. 1, the photocurable resin layer 23 can be laminated on the substrate 1, and information can be read or rewritten on the intended information recording layer 5 finally. The light-transmitting layer 10 can be formed.

As described above, according to the present invention, the light transmitting layer 1 for reading recorded information from the information recording layer 5 of the optical recording medium is provided.
0 can be formed to be thin and uniform in thickness, and the recording density of the optical recording medium can be increased.

The thickness of the photo-curable resin layer 23, which eventually becomes the light-transmitting layer 10, can be adjusted by rotating the liquid photo-curable resin 13 at a high speed, thereby adjusting the thickness. The light transmitting layer 10 having an arbitrary thickness of 10 to 300 μm can be formed.

The method of forming the laminated body 30 as described above is a case where the information recording layer 5 formed on the substrate 1 is embedded by pressing the substrate 1 with a roller. In this case, The liquid photo-curable resin 13 having a relatively high viscosity is used, but is not limited to this example.
As shown in FIG.
Can be inserted between the photocurable resin layer 23 and the substrate 1 and rotated at a high speed to embed the information recording layer 5 to form the laminate 30.

[Embodiment 2] Next, a case of manufacturing an optical recording medium having two information recording layers will be described. In this example, as shown in FIG. 2, the fine irregularities 2 are formed simultaneously with the injection molding of the substrate 1 simultaneously with the molding of the substrate 1, the reflective film 4 is formed thereon, and the information recording layer 5 is formed. A second information recording layer 35 is further formed on the information recording layer 5 from a light-transmitting resin layer 33 and a semi-reflective film 34, and information is read or written on the second information recording layer 35. An optical recording medium having a configuration in which a light transmitting layer 70 is formed is obtained.

First, as shown in FIG. 8, a stamper 11 having a diameter larger than that of the substrate constituting the optical recording medium finally used in the above-described first embodiment and having one main surface smooth is provided. Instead, the fine irregularities 21 forming the information recording layer
A stamper 21 on which a is formed is prepared.

In the following, the stamper 21 is mounted on a rotating base (not shown) and the liquid photocurable resin 13 is applied on the stamper 21 in the same manner as described in the first embodiment. After the stamper 21 is rotated at a high speed and the liquid photo-curable resin 13 is sufficiently stretched, the liquid photo-curable resin 13 is cured by irradiating the liquid photo-curable resin 13 with, for example, ultraviolet rays, as shown in FIG. The photo-curable resin layer 33 having a thickness of is formed.

At this time, the fine irregularities 21 a formed on the stamper 21 are transferred to the photocurable resin layer 33.

On the other hand, by the conventional method, the substrate 1 is transferred to the fine irregularities 2 and simultaneously with the thickness of 0.1 mm by injection molding.
A reflective film 4 of an Al vapor deposited film is formed on the fine irregularities 2 to form an information recording layer 5.

Next, as shown in FIG. 10, the surface of the substrate 1 obtained as described above, on which the information recording layer 5 is formed, and the photo-curable resin layer 33 are interposed via the photo-curable resin 3 for bonding. The roller 31 is rolled on the substrate 1 and pressure-bonded,
For example, the photocurable resin 3 is cured by irradiating ultraviolet rays. Here, a layer composed of the substrate 1, the information recording layer 5, and the photocurable resin layer 33 is referred to as a laminate 60.

Next, as shown in FIG. 11, the laminate 60 obtained as described above is peeled from the stamper 21. At this time, the photo-curable resin layer 33 is adjusted according to the outer diameter of the substrate 1.
For example, the mold is formed, and is made to conform to the substrate 1 and is separated from the stamper 21. By doing so, the fine irregularities 21 a of the stamper 21 are transferred to the photocurable resin layer 33, and the fine irregularities 33 a are formed on the photocurable resin layer 33.

Next, as shown in FIG. 2, a semi-reflective film 34 made of, for example, SiN is formed on the fine unevenness 33a of the photocurable resin layer 33 to which the fine unevenness 21a has been transferred by the stamper 21. Then, the second information recording layer 35 is formed.

Thereafter, a light transmitting layer 70 for reading or rewriting information is finally formed by the same method as in the first embodiment, and a two-layer optical recording medium can be manufactured. .

As shown in FIG. 2, in the optical recording medium having the two-layer structure manufactured as described above, the irradiation light L from the optical head to the information recording layer 5 is indicated by a broken line in FIG. Thus, the recording or reproduction is performed by focusing, and the irradiation light L from the optical head is focused on the second information recording layer 35 as shown by the solid line in FIG. Perform playback.

In the first embodiment, the stamper 1
1 is, for example, a Ni stamper, a so-called mirror stamper having a smooth surface is used. However, the present invention is not limited to this example. A transparent glass plate having a high transmittance for the light used, for example, ultraviolet light, can be used.

That is, as shown in FIG. 12, the substrate 1 is inserted into the center hole 1h, and the center pin 80a of the rotation base 80 is inserted and placed on the rotation base 80, and the information recording of the substrate 1 is performed. After inserting a liquid photocurable resin or the like for bonding, the layer 5 and the transparent glass plate 51 are matched via the photocurable resin layer 23, and then, as shown in FIG. Is rotated to stretch the photocurable resin.

As described above, when the transparent glass plate 51 is used instead of the mirror stamper, in the step of matching the substrate 1 with the photocurable resin layer 23 via the liquid photocurable resin, When the photocurable resin is cured by, for example, irradiating ultraviolet rays, it can be irradiated from the side opposite to the substrate 1, that is, from the transparent glass plate 51 side. When an Al vapor-deposited film is applied as the reflective film 4 constituting the information recording layer 5 of the substrate 1, the Al vapor-deposited film has a low transmittance of ultraviolet rays, and thus the transparent glass plate 51 is used as described above.
If ultraviolet light can be irradiated from the side, it is extremely effective for photocuring the liquid photocurable resin.

In the second embodiment, the stamper 21 is, for example, a Ni stamper having fine irregularities 21a formed on the surface. However, the present invention is not limited to this example. Instead of stamper 21,
In the same manner as described above, a glass stamper in which fine irregularities are formed with a photoresist, for example, can be used for a transparent glass plate having a high transmittance to light used for photocuring, for example, ultraviolet rays.

In the above-described embodiment, the reflection film is made of Al.
Although formed by a vapor deposition film, the present invention is not limited to this example, and Au or the like that can transmit more ultraviolet rays than Al can be applied.

Further, in the above-described embodiment, the case where an optical recording medium having a single-layer or double-layer structure is manufactured has been described.
The present invention can be similarly applied to the case of producing an optical recording medium having a multilayer structure having more than two layers.

[0041]

According to the present invention, the light transmitting layer for reading out recorded information from the information recording layer of the optical recording medium can be formed thin, so that the recording density of the optical recording medium can be increased.

According to the present invention, when the light transmitting layer 10 is formed of a conventional transparent sheet, it is not necessary to consider the optical characteristics of the transparent sheet, such as birefringence.
In addition, it was possible to solve the problems in the process such as the attachment of fine dust due to the static electricity of the transparent sheet.

Further, when a conventional liquid photocurable resin is applied on a substrate and then a light transmitting layer is formed by a method of curing on the substrate, the liquid photocurable resin is applied on the substrate. It was possible to solve the problem that the outermost peripheral portion became thicker than the inner peripheral portion due to surface tension, and the thickness of the light transmitting layer was non-uniform.

Further, according to the present invention, an information recording layer of an optical recording medium is formed by forming a photocurable resin layer having a uniform thickness in advance on one main surface of a stamper and bonding the same to a substrate. Since a light transmitting layer for reading recorded information from the substrate was formed, the bending of the substrate caused when the photocurable resin was cured could be effectively avoided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical recording medium in which a light transmitting layer is formed on an information recording layer.

FIG. 2 is a schematic sectional view of an optical recording medium having a two-layer structure.

FIG. 3 shows a manufacturing process diagram of the optical recording medium of the present invention.

FIG. 4 shows a manufacturing process diagram of the optical recording medium of the present invention.

FIG. 5 is a schematic view of a laminate in a step of manufacturing the optical recording medium of the present invention.

FIG. 6 is a view showing a step of separating a substrate and a stamper in a step of manufacturing the optical recording medium of the present invention.

FIG. 7 shows a manufacturing process diagram of a laminate in the manufacturing process of the optical recording medium of the present invention.

FIG. 8 shows a manufacturing process diagram of an optical recording medium having a two-layer structure of the present invention.

FIG. 9 shows a manufacturing process chart of an optical recording medium having a two-layer structure of the present invention.

FIG. 10 is a schematic view of a laminate in a step of manufacturing an optical recording medium having a two-layer structure of the present invention.

FIG. 11 is a view showing a step of separating a substrate and a stamper in a step of manufacturing an optical recording medium having a two-layer structure according to the present invention.

FIG. 12 is a schematic sectional view of an optical recording medium when a glass stamper is used.

FIG. 13 is a schematic cross-sectional view of an optical recording medium using a glass stamper.

FIG. 14 shows a schematic sectional view of a conventional optical recording medium.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Substrate, 2, 21a, 33a Fine unevenness, 4 Reflection film, 5 information recording layer, 6 protective film, 10, 70 light transmission layer, 11, 21 stamper, 13 liquid photocurable resin, 23, 33 photocurable resin Layer, 30, 60 laminate, 31 roller, 34 semi-reflective film, 35 second information recording layer, 43 low-viscosity liquid photocurable resin, 80a center pin

Claims (3)

[Claims] 1. A step of uniformly applying a liquid photocurable resin on one main surface of a stamper having a contour larger than a contour of a substrate constituting an optical recording medium, and curing the liquid photocurable resin. Forming a photocurable resin layer, and laminating the information recording layer forming surface of the substrate constituting the optical recording medium and the photocurable resin layer to form a laminate, Separating the laminate from the stamper, and sequentially performing these steps. 2. The method for manufacturing an optical recording medium according to claim 1, wherein said one main surface of said stamper is smooth. 3. The method according to claim 1, wherein the one main surface of the stamper has fine irregularities for transferring fine irregularities that finally form an information recording layer of the optical recording medium.
3. The method for producing an optical recording medium according to item 1.