JPH08306085A - Production of optical recording medium having multilayered structure - Google Patents

Abstract

PURPOSE: To surely avoid the interference of radiated light between information recording layers by forming a middle layer interposed between the recording layers by photopolymn. with a planar stamper. CONSTITUTION: A middle layer is formed by triply applying and photo- polymerizing a UV-curing resin with a planar stamper. A 2nd information recording layer 2 is further formed on the resin by a 2P method. In this case, a stamper 14 is pressed toward an optical disk part 11 through the UV-curing resin 33 and the resin is cured by irradiation with UV from the rear part of the optical disk part 11. The 2nd information recording layer 2 is formed with the stamper 14 on the previously formed middle layers 31, 32 in a superposed state and the transparent middle layer 3 having 40μm total thickness including the thickness of the resin 33 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multilayer optical recording medium.

[0002]

2. Description of the Related Art As an optical recording medium for recording various information such as audio, video, etc., the amount of information that can be recorded on an optical recording medium such as an optical disk or a card for recording or / and reproducing the light In order to increase the size, it is desired that the information recording layer has a multilayer structure.

[0003]

As a multilayer structure optical recording medium, as shown in the schematic sectional view of FIG. 4, at least a first information recording layer 1 and a second information recording layer 2 are an intermediate layer 3. Are stacked through. In this case, it is possible to simplify the drive device so that the optical recording or / and reproduction of the information can be performed by irradiation from the same side of the recording medium by, for example, one set of optical heads.
And it is desirable for increasing the access speed in continuous recording or / and reproducing of both information recording layers 1 and 2.

In this case, optical recording or / and
For example, the first information recording layer 1 located on the side where the reproduction light is irradiated has a structure having a required reflectance and a required transmittance, and the second information recording layer 2 has a high reflectance information recording. In the optical recording or / and reproducing on the first information recording layer 1, the irradiation light 21L from the optical head is focused to record or / and reproduce the second information recording. In the optical recording and / or reproducing on the layer 2, the recording light and / or reproducing is performed by focusing the irradiation light 22L on the second information recording layer.

However, in this case, when the distance between the first information recording layer 1 and the second information recording layer 2 is small, there arises a problem of interference of irradiation light. Therefore, it is desired that the distance between the first information recording layer 1 and the second information recording layer 2 be made somewhat larger than the wavelength of the irradiation light. For example, when the wavelength of the irradiation light is 630 nm, It is desired that the thickness of the intermediate layer 3 be as thick as about 40 μm.

For example, the recorded information is recorded as concave and convex pits, and the recorded information is read out by light irradiation in a ROM (Re
In the case of configuring an ad-only memory type multi-layered optical disc, the first recording information layer 1 is formed by the optical disc unit 11 by injection molding, and the recording information layer 2 for the second recording is formed by the photopolymerization method. It is possible. In this case, the intermediate layer 3 may be formed by applying a UV-curing resin by a spin coating method, for example, but in the case of such a spin coating method, it is entirely covered in the central portion and the outer peripheral portion of the disk. It is difficult to apply the film to a uniform and uniform thickness, which causes problems such as deterioration of optical characteristics of the finally manufactured recording medium and deterioration of yield.

In the present invention, in the above-mentioned multilayer structure optical recording medium having at least the first and second information recording layers, the intermediate layer between the respective information recording layers is sufficiently thick,
Moreover, it is possible to manufacture a multi-layered optical recording medium which is formed uniformly and uniformly and which has excellent optical characteristics and thus excellent S / N and C / N recording and / or reproducing characteristics. Provided is a method for manufacturing the optical recording medium having the multi-layer structure.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing a multi-layered optical disc in which at least a first recording information layer and a second recording information layer are laminated with an intermediate layer interposed between them. Upon formation, a photopolymerization operation using a flat stamper having a flat surface is performed, for example, by repeating, to manufacture an intended multi-layered optical recording medium.

[0009]

As described above, in the method of the present invention, the intermediate layer interposed between the recording information layers is formed by the photopolymerization method using a flat stamper. In addition, by repeating this photopolymerization by the required number of times, this intermediate layer is formed to a necessary and sufficient thickness, and even over the entire surface to a uniform thickness. be able to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the manufacturing method of the present invention, various information is recorded as concave and convex pits, and the so-called ROM type multi-layered optical recording medium for audio and video which reads out the recorded information by light irradiation, especially the information recording layer An example of obtaining an optical disc having two layers will be described with reference to the process chart of FIG.

In this example, as shown in the sectional view of FIG. 1A, the optical disk unit 11 having the first information recording layer 1 formed thereon.
Is manufactured by injection molding using a transparent resin such as a resin having a light transmitting property such as PC (polycarbonate).
This injection molding is performed, for example, as shown in the sectional view of FIG. 3 in a metal stamper in which a concave and convex pattern of information corresponding to information to be recorded as the first information recording layer is formed in the cavity of the mold 40. Master stamper 41
Is placed, and the heat-melted PC is injection-molded in this cavity.

The optical disk unit 11 formed in this way
On the first information recording layer 1, as shown in FIG. 1B, an optical layer 12 such as a SiN layer for controlling the first information recording layer 1 to have a required transmittance and reflectance is formed by sputtering, for example. Formed by.

After that, an intermediate layer is formed on the first information recording layer 1 of the optical disc section 11. Particularly, in the present invention, this intermediate layer is formed by using, for example, an ultraviolet curable resin using a flat stamper. By a photopolymerization method (hereinafter referred to as 2P method) according to 1. That is, FIG.
As shown in C, an ultraviolet curable resin is applied onto the first information recording layer 1 of the optical disc unit 11, and a flat stamper 13 having a flat mirror-finished flat surface 13a is pressed toward the optical disc unit 11 from its back, UV irradiation is performed from the back of the optical disk unit 11, that is, the side opposite to the side having the first information recording layer 1 to cure the UV curable resin.
2P is performed to form the first intermediate layer 31.

Then, as shown in FIG. 1D, the second intermediate layer 32 is superposed on the first intermediate layer 31 by performing the second 2P in the same manner as the above-mentioned first intermediate layer 31. To form. Similarly, although not shown, in each 2P step, for example, the first to fourth 2P operations each having a thickness of 8 μm, for example, are performed to form a light transmissive resin layer having a thickness of 32 μm.

Further, as shown in FIG. 2A, the second information recording layer 2 is formed on this resin layer by the 2P method.
That is, in this case, the stamper 14 on which the information concavo-convex pattern corresponding to the information to be recorded is formed as the second information recording layer is pressed toward the optical disc unit 11 through the similar ultraviolet curable resin 33, and the like. Optical disc unit 1
The ultraviolet curing resin is cured by irradiating ultraviolet rays from the back part of 1. In this way, the intermediate layers 31, 3 formed previously are formed.
The second information recording layer 2 is formed by molding with the stamper 14 so as to be overlapped with the second layer 2, and the total thickness including the thickness of the resin 33 for forming the second information recording layer 2 is, for example, 40.
A light-transmissive intermediate layer 3 having a thickness of μm is formed.

Since the intermediate layer 3 thus formed is formed by using a flat stamper and is formed by repeatedly stacking layers, it is sufficient that each part is uniform and uniform in thickness. Can be formed as a thick intermediate layer.

The stamper 14 is eliminated as shown in FIG. 2B. By doing so, the second information recording layer 2 is formed by a pattern in which the concavo-convex pattern of the stamper 14 is reversed. A reflective film 15 made of an Al vapor deposition film or the like is formed on the second information recording layer, and a protective layer 16 made of a photocurable resin or the like is formed on the reflective film 15. In this way, the intended multi-layered optical recording medium in which the first and second information recording layers 1 and 2 are laminated is constructed.

When reading each record from each of the first and second information recording layers 1 and 2 of the multi-layered optical recording medium obtained as described above, for example, as shown in FIG. It can be reproduced from the back surface of the same by reproducing light from the same optical pickup.
For example, reproduction on the first information recording layer 1 is performed by irradiation with the irradiation light 21L focused on the first information recording layer 1, and is performed by irradiation with the irradiation light 22L focused on the second information recording layer 2. . At this time, it is desirable to select the light transmittance of the first information recording layer 1 to 30% to 80% and the reflectance of 20% to 50% by the above-mentioned optical layer 12, and the second information recording layer 2 Reflective film 15
The reflectivity at can be chosen to be 100%.

In the present specification, the light transmittance, the transmittance, the reflection, the reflectance and the like refer to the optical characteristics with respect to the reproduction light irradiated to the finally obtained multilayer optical recording medium. .

Further, in the above-mentioned example, the case where the multi-layer structure optical recording medium having the two-layer structure of the first and second information recording layers 1 and 2 is obtained has been described, but it is applied to the case where the structure has three or more layers. However, the formation of each information recording layer is not limited to the injection molding method and the 2P method, and various manufacturing methods can be adopted.

Further, in the above-mentioned example, the present invention is applied to the multi-layered optical recording medium having the ROM type structure, but the multi-layered optical recording and reproducing by the modes such as magneto-optical recording and phase change recording are possible. The present invention can be applied to the production of multilayer structured optical recording media having various configurations such as applicable to structured optical recording media.

[0022]

As described above, according to the manufacturing method of the present invention, in manufacturing a multilayer optical recording medium, the formation of the intermediate layer interposed between the plurality of information recording layers is performed by using a photo stamper using a flat stamper. Since it is formed by the malization method, it can be formed on a uniform plane, and since it is formed by stacking by repeating it, it is possible to form the intermediate layer between the information recording layers uniformly and accurately to a required large thickness. Therefore, when recording or / and reproducing by light irradiation, the problem of interference of irradiation light between the information recording layers can be surely avoided, and excellent optical characteristics, and therefore high S / N, C / A multilayer optical recording medium having N recording / reproducing characteristics can be manufactured with high yield.

[Brief description of drawings]

FIG. 1 is a partial process chart of an example of a method for manufacturing a multilayer optical recording medium according to the present invention. A is a cross-sectional view of one step. B is a sectional view of one step. C is a cross-sectional view of one step. D is a cross-sectional view of one step.

FIG. 2 is a partial process chart of an example of a method for manufacturing a multilayer optical recording medium according to the present invention. A is a cross-sectional view of one step. B is a sectional view of one step.

FIG. 3 is a schematic cross-sectional view of an example of an injection molding apparatus in the method of manufacturing a multilayer optical recording medium according to the present invention.

FIG. 4 is a schematic cross-sectional view of an example of a multilayer optical recording medium that can be obtained by the manufacturing method of the present invention.

[Explanation of Codes] 1 First information recording layer 2 Second information recording layer 3 Intermediate layer 11 Optical disc section 12 Optical layer 13 Flat stamper 14 Stamper 15 Reflective film 40 Mold 41 Metal stamper

Claims (2)

[Claims] 1. A method for manufacturing a multi-layered optical disc comprising at least a first information recording layer and a second information recording layer laminated with an intermediate layer interposed between them. A flat stamper having a flat surface when forming the intermediate layer. A method for manufacturing an optical recording medium having a multi-layer structure, which comprises performing a photopolymerization operation according to. 2. The method of manufacturing an optical recording medium having a multi-layer structure according to claim 1, wherein the photopolymerization by the flat stamper is repeated a plurality of times.