JPH1125516A - Optical disk and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively manufacture the optical disk in which printed layers are provided to visually cover approximately the entire surfaces of the both sides of the disk and a recording and a reproducing are conducted on the both sides. SOLUTION: On the top surface of a transparent and circular plate shaped optical disk substrate 1a, grooves are formed to provide a projected-recessed patterns corresponding to recording information. On top of the grooves, a semitransparent reflection film 2a is formed to have a prescribed reflectivity against reproducing optical beams and a prescribed transmissivity in a visible optical region. Moreover, a printed layer 4a is formed on the film 2a by an electrophotographic printing to print visual information including characters and graphics to complete the constitution of the substrate 1a. Then, the layer 4a of a first optical disk substrate 11a and a printed layer 4b of a second optical disk substrate 11b are placed opposite to each other and are joined through an adhesive layer 12 to form an optical disk 21 of a both surface recording and reproducing type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk as an optical information recording medium and a method for manufacturing the same.
The present invention relates to a double-sided recording / reproducing optical disk having a print layer for displaying recorded information content and the like, and a method of manufacturing the optical disk.

[0002]

2. Description of the Related Art Conventionally, an optical disc is generally provided with a printed layer on which visual information such as symbols and symbols are displayed so that the recorded information can be perceived. For example, in the case of an optical disk of a single-sided recording / reproducing format such as a CD (compact disk), a printing method such as screen printing or offset printing is used to directly apply the information signal onto the protective layer located on the back side of the information signal readout surface. A printed layer is provided, and it is possible to display a design or a symbol on almost the entire surface.

On the other hand, in the case of a double-sided recording / reproduction type optical disk capable of recording a larger amount of information, a portion on which a print layer can be provided is very small, such as near the center of the optical disk, so as not to hinder reading of an information signal. It was limited to a small area, and the area where symbols and symbols could be displayed was limited. On the other hand, in Japanese Patent Application Laid-Open No. 9-81964, two optical disk substrates in which an optical information recording layer, a protective layer, and a print layer are sequentially laminated on an optical disk substrate are joined with the print layer side facing each other. In an optical disc of a double-sided recording / reproducing format, an optical information recording layer has a predetermined transparency, and a print layer is formed via an optical information recording layer and a protective layer from an optical disc substrate side of each optical disc substrate, which is a reading surface of an information signal. What can be visually recognized is disclosed.

[0004] With such a configuration, it is stated that even with an optical disk of the double-sided recording / reproducing type, a wide area for printing and displaying symbols and symbols can be secured without obstructing the reading of information signals.

[0005]

However, since the above-mentioned protective layer is formed by curing the applied resin,
There is a possibility that the optical disc substrate may be warped due to shrinkage during curing. Particularly, when manufacturing an optical disc of a double-sided recording / reproducing type by bonding two optical disc substrates together,
This warpage was a major obstacle. Further, when a printing layer is formed on the protective layer by a printing method such as screen printing or offset printing, a step occurs in the printing layer due to unevenness due to the thickness of the ink. If the warpage of the substrate and the step due to printing overlap, it becomes difficult to uniformly manufacture a single double-sided recording / reproducing optical disk, resulting in a decrease in yield and an increase in manufacturing cost. Was. Therefore, it has been required to eliminate at least one of the warpage of the substrate due to the protective layer and the step due to printing.

In screen printing and offset printing, a complicated plate-making process is required to produce a printing plate, so that the production efficiency is low, and it is difficult to produce small lots. . SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and has as its object to provide a homogeneous and inexpensive double-sided recording / reproducing optical disk having a print layer that can be visually recognized on substantially both sides thereof, and a method of manufacturing the same.

[0007]

Therefore, according to the first and twelfth aspects of the present invention, a translucent reflective film having a predetermined reflectance for a reproducing light beam and a predetermined transmittance in a visible light region is provided. An optical information recording layer including a film, provided on one surface of each optical disk substrate, a first optical disk substrate and a second optical disk substrate, wherein the first optical disk substrate and the second optical disk substrate A printed layer on which visual information is printed is formed on at least one of the optical information recording layers, and the first optical disc substrate and the second optical disc substrate are placed on the side on which each optical information recording layer is provided. The optical disk is bonded with an adhesive layer with the surfaces facing each other, and the printed layer is visually recognized through an optical disk substrate of an optical disk substrate provided with the printed layer and an optical information recording layer.

As described above, since the configuration is such that the protective layer which causes the warpage of the disk substrate is removed, even if a slight level difference occurs due to the printed layer, the influence is small, and an optical disk having a substantially uniform overall is manufactured. be able to. In addition, since the two optical disk substrates are bonded with their respective substrate sides outside, there is no external influence on the optical information recording layer and the printing layer, and there is no problem in performance such as durability.

In the invention according to claim 2 and claim 13, the printing layer forms a thin printing layer using toner by electrophotographic printing which does not require a plate making process, and a step due to the printing layer is minimized. Make it smaller. In the case where a protective layer is required for the convenience of the process, etc., claims 3 and 4
As in the invention according to 14, between the optical information recording layer and the printing layer, a protective layer for protecting the optical information recording layer,
A transparent conductive film having a surface electric resistance of 1 × 10 ⁻¹² Ω or less and formed of a transparent conductive material having a predetermined transmittance is laminated in this order. In general, the protective layer is formed of an ultraviolet curable resin or the like and has a high electric resistance. Therefore, it is difficult to uniformly transfer the toner charged by an electrophotographic method on the protective layer to form a print layer. By providing a transparent conductive film on the substrate, a printing layer can be formed by electrophotographic printing.

This transparent conductive material is made of ITO, In ₂ O ₃ , ZnO and SnO.
_If any one of the two is used, it is possible to obtain a film having a sufficiently low electric resistance value necessary for uniformly performing electrophotographic printing. Further, if the translucent reflective film is formed of a conductive material as in the invention according to claims 5 and 15, a printing layer can be formed directly on the translucent reflective film by electrophotographic printing. Can also. In this case, as the conductive material, Au, Ag,
Cu, Si, and at least one of these elements
It can be easily manufactured by using an alloy selected from alloys mainly composed of one.

On the other hand, as in the invention according to claim 7 and claim 16, the optical information recording layer is formed of a transparent conductive material having a predetermined transmittance, wherein the translucent reflection film is formed of a non-conductive material. And a transparent conductive film laminated on the translucent reflective film, a print layer can be directly formed thereon by electrophotographic printing. If a substance having a refractive index of 2.0 or more is used as the non-conductive material as described above, it is possible to obtain reflected light sufficient to read out an information signal at the interface with the optical disk substrate. . Specific examples of such a non-conductive material include ZnS, Ti
Any one of O ₂ , ZnSe, SiC, and Si ₃ N ₄ can be used.

In this case, the transparent conductive material may be made of ITO, In ₂ O ₃ , Z
Any one of nO and SnO ₂ may be used. In the invention according to claim 11, the translucent reflective film has a reflectance of 15 to 75% with respect to a reproduction light beam and a transmittance in a visible light region of 10% or more.
A light beam for reading recorded information is sufficiently reflected, and visible light is transmitted through the optical disk substrate and the optical information recording layer so that a design or symbol displayed on the print layer can be visually recognized.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an example of the layer configuration of the optical disc of the present invention. On the upper surface of the transparent disk-shaped optical disk substrate 1a, there is provided a groove on which an uneven pattern corresponding to recorded information is formed, on which a predetermined reflectance for a reproduction light beam and a predetermined transmission in a visible light region are provided. A translucent reflective film 2a having a specific ratio is formed.
The portion of the upper surface of the optical disc substrate 1a where the groove is provided and the translucent reflection film 2a correspond to the optical information recording layer 3a.

On the optical information recording layer 3a, there is formed a printed layer 4a on which visual information such as characters and patterns are printed, and the first optical disk is provided from the optical disk substrate 1a to the printed layer 4a. It corresponds to the base 11a. Then, the first optical disk substrate 11a and the second optical disk substrate 11b having the same configuration are joined with the printed layer 4a and the printed layer 4b opposed to each other via an adhesive layer 12, thereby forming a double-sided recording / reproducing format. Optical disk 21 is formed.

FIGS. 2A to 2D are sectional views showing steps of manufacturing the optical disk 21. FIG. First, as shown in FIG. 2A, the optical disk substrate 1a of the first optical disk base 11a is made of polycarbonate or polymethyl methacrylate using a stamper (not shown) having a concavo-convex pattern on the surface opposite to recorded information. Etc. are formed by injection molding of a transparent synthetic resin.

Next, as shown in FIG. 2B, a translucent reflective film 2a is formed on the surface of the optical disk substrate 1a on which the concavo-convex pattern is formed by forming Au, Ag, Cu, Si, and these elements. A conductive material selected from alloys containing at least one as a main component, and using a sputtering method, a vacuum evaporation method, or the like, adjusting the thickness of the conductive material to 15 to 75% of the reproducing light beam. Reflectance and visible light range (wavelength 380
(800 nm) at a transmittance of 10% or more.

Then, on the translucent reflection film 2a, FIG.
As shown in (C), the printing layer is formed by various printing methods such as screen printing, offset printing, and electrophotographic printing. When the electrophotographic printing is used, the printing layer 4a can be formed thinner with toner, the step due to the presence or absence of printing is reduced, and it is convenient to uniformly form the entire optical disc. In electrophotographic printing, if the electric resistance value of the underlayer surface is high, the charge of the charged toner accumulates and a transfer failure occurs. Because it is membrane 2a,
A good print layer can be formed without transfer failure.

A second optical disk base 11b is formed in the same manner as the first optical disk base 11a thus formed,
As shown in FIG. 2 (D), both of the surfaces are provided with the respective optical information recording layers 3a (3b), that is, the printing layers 4a and 3b.
The optical disk 21 of the double-sided recording / reproducing type is formed by bonding the optical disk 21 with the a (4b) side facing each other via an adhesive layer 12 formed of an epoxy adhesive or the like.

In this optical disk 21, the translucent reflection film 2a
Has a reflectance of 15 to 75% with respect to the reproducing light beam, and has a transmittance of 10% or more in the visible light region. Therefore, the optical disc substrate 1a of the optical disc base 11a and the optical information recording layer 3a are separated from each other. The printed layer 4a can be visually recognized through the optical disk 21 (similarly on the side of the optical disk base 11b), and various visual information on the recorded contents of the optical disk 21 can be written on almost both sides of the optical disk 21 by using characters and designs. Can be displayed.

Since the above-described optical disk base 11a and optical disk base 11b are not provided with a conventional protective layer, there is no warpage due to shrinkage during formation of the protective layer, and the two optical disk bases are joined to form a uniform optical disk. The optical disk 21 can be easily formed. Further, the printing layer 4a (4
By forming b) thin by an electronic printing method, the entirety of one optical disc 21 can be formed more uniformly, the yield can be improved, and the manufacturing cost can be reduced.

In addition, unlike the screen printing and the offset printing, the electronic printing method does not require a complicated plate-making process for manufacturing a printing plate, and enables flexible production corresponding to a small lot. Further, when it is necessary to provide a resin protective layer 5a (5b) on the optical information recording layer 3a (3b) to protect the optical information recording layer 3a (3b) due to the production process or the like, as shown in FIG. Then, a transparent conductive film 6a (6b) having a surface electric resistance of 1 × 10 ⁻¹² Ω or less is formed on the protective layer 5a (5b). The transparent conductive film 6a (6
According to b), the conductivity of the base required for forming the printing layer 4a (4b) by electrophotography can be ensured.

The transparent conductive film 6a (6b) comprises a protective layer 5a
On top of (5b), ITO, In ₂ O ₃ , ZnO, and Sn
By using any one of O ₂ transparent conductive materials by a sputtering method or the like, and transferring the toner thereon by an electrophotographic method, a good print layer 4a (4b)
Can be obtained. In this case, the optical disk substrate 12a (12b) may be warped due to the protective layer 5a (5b). However, by forming the print layer 4a (4b) thinly by electrophotography, the optical disk substrate 12a and the optical disk substrate 12b are formed. Can be formed as uniformly as possible.

When the translucent reflection film is formed of a non-conductive material, as shown in FIG.
On top of (2b) ITO, In ₂ O ₃ , ZnO and Sn
A transparent conductive film 7a (7b) having a surface electric resistance of 1 × 10 ⁻¹² Ω or less is formed using any one of the O ₂ transparent conductive materials. That is, the optical information recording layer 3a (3b)
Is composed of a portion provided with a groove on the upper surface of the optical disk substrate 1a (1b), a non-conductive semi-transparent reflective film 2a (2b) and a transparent conductive film 7a (7b), as described above. A good printing layer 4a (4b) can be formed on the target information recording layer 3a (3b) by electrophotography.

The non-conductive material used to form the translucent reflective film 2a (2b) includes the optical disk substrate 1a
In order to obtain reflected light sufficient to read an information signal at the interface with (1b), a substance having a refractive index of 2.0 or more is preferable.
Specific substances include ZnS, TiO ₂ , ZnSe,
SiC, and Si ₃ N ₄ . In the above-described example, the configuration in which the print layer is provided on both the first optical disk substrate and the second optical disk substrate has been described. However, a configuration in which the print layer is provided on only one of them may be adopted.

[0025]

The embodiments will be described below. Example 1 A polycarbonate resin was molded using an injection molding machine equipped with a stamper created based on an information signal to obtain a substrate having an outer diameter of 120 mm and a thickness of 0.6 mm.

A translucent reflective film of Au was obtained on the signal transfer surface of the substrate using a sputtering apparatus (Balzas CDI-911) under the conditions of a power supply of 0.8 kW and a sputtering time of 2.7 seconds. DVD evaluation machine (Pulstec DDU-1000:
When the reflectance (the ratio of the reflected light to the incident laser light) was measured at a reproduction laser wavelength of 650 nm and a laser output of 0.3 mW, the reflectance was 56%. An electrophotographic printing machine (Digital Color Copier: Phaser550J manufactured by Sony Tektronix) directly prints designs and characters on this translucent reflective film to obtain a first optical disk substrate, and a second optical disk substrate in the same manner. Was.

Then, a hot melt adhesive was applied onto the printed layers of the first optical disk substrate and the second optical disk substrate, respectively, and the adhesives were overlapped, pressed and joined.
Here, looking at the design from each board side,
The details of the design including the quarter-square characters were clearly legible (design visibility = ○; see Table 1). Then a commercially available DV
When applied to the D player, both sides could be reproduced without any problem (player reproduction = ○; see Table 1).

[Example 2] Cu was used for the translucent reflection film,
An optical disk was prepared in the same manner as in Example 1, except that the sputtering conditions were changed. Table 1 shows the evaluation results. Example 3 After forming a translucent reflective film in Example 1, an acrylic resin (SKY SKIN, manufactured by Sony Chemical Co., Ltd.)
5000) is applied by spin coating, cured by ultraviolet irradiation, a 7 μm-thick optical buffer layer is provided, and a transparent conductive layer made of ITO is formed on the surface thereof using a sputtering apparatus (Balzas CDI-911). Electric resistance is 1
It was formed by controlling the film thickness so as to be × 10 ⁻¹² Ω or less. Thereafter, electrophotographic printing and bonding of the substrates were performed in the same manner as in Example 1 to produce an optical disk. Table 1 shows the evaluation results.

[Embodiment 4] Cu was used for the translucent reflection film,
An optical disk was prepared in the same manner as in Example 3, except that the sputtering conditions were changed. Table 1 shows the evaluation results. Example 5 A polycarbonate resin was molded using an injection molding machine equipped with a stamper created based on an information signal to obtain a substrate having an outer diameter of 120 mm and a thickness of 0.6 mm.

On the signal transfer surface of the substrate, a ZnS thin film was formed by RF sputtering to obtain a translucent reflective film. On this semi-transparent reflective film, further, using a sputtering device,
A transparent conductive layer made of TO has a surface electric resistance of 1 × 10
It was formed by controlling the film thickness so as to be ^-12 Ω or less. Thereafter, electrophotographic printing and bonding of the substrates were performed in the same manner as in Example 1 to produce an optical disk. Table 1 shows the evaluation results.

Example 6 An optical disk was produced in the same manner as in Example 5, except that TiO ₂ was used for the translucent reflective film and the sputtering conditions were changed. Table 1 shows the evaluation results. Example 7 An optical disk was produced in the same manner as in Example 5, except that ZnSe was used for the translucent reflective film and the sputtering conditions were changed. Table 1 shows the evaluation results.

Example 8 An optical disk was prepared in the same manner as in Example 5, except that SiC was used for the translucent reflective film and the sputtering conditions were changed. Table 1 shows the evaluation results.

[0033]

[Table 1]

As can be seen from the evaluation results in Table 1, in all of Examples 1 to 8, design visibility =＝ (design discrimination is possible) and player reproduction =＝ (both voice and image are normally reproduced). .

[0035]

As described above, according to the first and twelfth aspects of the present invention, warpage of the optical disk substrate is prevented as much as possible by eliminating the protective layer.
There is an effect that an optical disk of a double-sided recording / reproducing format in which the entire board surface is uniform can be manufactured. Further, the yield is improved, and the step of forming the protective layer is omitted, so that there is an effect that the manufacturing cost can be reduced.

According to the second and thirteenth aspects of the present invention, by forming a thin print layer using toner in electrophotographic printing, the steps due to the print layer are made as small as possible, and There is an effect that the whole can be made more uniform. Further, since the electrophotographic printing does not require a plate making process, there is an effect that the production can be performed at low cost and flexibly in a small lot.

According to the third and fourteenth aspects of the present invention, even when it is necessary to provide a protective layer due to a process or the like, the printing layer can be formed by electrophotographic printing. There is an effect that an optical disk of a double-sided recording / reproducing format in which the entire board surface is as homogeneous as possible can be manufactured. According to the fourth and tenth aspects of the present invention, a transparent conductive film having a sufficiently low electric resistance value can be obtained, and the toner of electrophotographic printing can be uniformly transferred on the transparent conductive film to achieve good printing. There is an effect that a layer can be formed.

According to the fifth and fifteenth aspects of the present invention, by forming the translucent reflective film of a conductive material, a print layer can be formed thereon directly by electrophotographic printing. This has the effect. Further, according to the invention of claim 6, there is an effect that a translucent reflective film made of a conductive material having sufficient characteristics for performing electrophotographic printing can be easily formed.

According to the seventh and sixteenth aspects of the present invention, even when the translucent reflective film is formed of a non-conductive material, the printing layer can be formed by electrophotographic printing. There is. Claims 8 and 9
According to the invention, there is an effect that a translucent reflective film made of a non-conductive material capable of obtaining reflected light sufficient to read an information signal at an interface with an optical disk substrate is obtained.

According to the eleventh aspect of the present invention, a light beam for reading recorded information is sufficiently reflected, and the printed layer is only visible through the optical disk and the optical information recording layer. There is an effect that visible light can be transmitted.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a layer configuration of an optical disc of the present invention.

FIG. 2 is a diagram for explaining a manufacturing process of the optical disc of the present invention.

FIG. 3 is a longitudinal sectional view showing another example of the layer configuration of the optical disc of the present invention.

FIG. 4 is a longitudinal sectional view showing still another example of the layer configuration of the optical disc of the present invention.

[Explanation of symbols]

 1a, 1b Optical disk substrate 2a, 2b Translucent reflective film 3a, 3b Optical information recording layer 4a, 4b Printing layer 5a, 5b Protective layer 6a, 6b Transparent conductive film 7a, 7b Transparent conductive film 11a, 12a, 13a First optical disk Substrates 11b, 12b, 13b Second optical disc substrates 21, 22, 23 Optical discs

Claims (16)

[Claims] An optical information recording layer including a translucent reflective film having a predetermined reflectance for a reproduction light beam and a predetermined transmittance in a visible light region is provided on each optical disk substrate. A first optical disk base and a second optical disk base provided on one surface, wherein visual information is printed on at least one of the optical information recording layers of the first optical disk base and the second optical disk base; An optical disc in which a printed layer is formed, and the first optical disc base and the second optical disc base are joined via an adhesive layer with their respective surfaces on which optical information recording layers are provided facing each other, An optical disc, wherein the printed layer is visually recognized through an optical disc substrate of an optical disc substrate provided with the printed layer and an optical information recording layer. 2. The optical disk according to claim 1, wherein said print layer is formed by electrophotographic printing. 3. The method according to claim 1, further comprising the step of:
A protective layer for protecting the optical information recording layer;
Electric resistance 1 formed of a transparent conductive material having a high resistivity
× 10 ^-12Ω or less and a transparent conductive film of
The optical disc according to claim 2, wherein the optical disc is used. 4. The transparent conductive material is made of ITO, In,
₂ O _3, ZnO, and an optical disk according to claim 3, characterized in that one of SnO ₂ is one. 5. The transflective film according to claim 1, wherein the translucent reflective film is formed of a conductive material.
An optical disc according to any one of the above. 6. The conductive material is made of Au, Ag, Cu, S
6. The optical disk according to claim 5, wherein the optical disk is selected from i and an alloy containing at least one of these elements as a main component. 7. The optical information recording layer, wherein the translucent reflective film is formed of a non-conductive material, is formed of a transparent conductive material having a predetermined transmittance, and is laminated on the translucent reflective film. 3. The optical disk according to claim 2, comprising a transparent conductive film formed. 8. The optical disk according to claim 7, wherein said non-conductive material is a substance having a refractive index of 2.0 or more. 9. The non-conductive material comprises ZnS, TiO ₂ ,
ZnSe, an optical disk according to claim 8, characterized in that any one of SiC, and Si ₃ N _4. 10. The transparent conductive material includes ITO, In,
10. The semiconductor device according to claim 7, which is any one of ₂ O ₃ , ZnO, and SnO _2.
An optical disc according to any one of the above. 11. The translucent reflective film has a reflectivity of 15 to 75% with respect to a reproduction light beam, and a transmissivity in a visible light region of 10% or more.
11. The optical disc according to any one of 10. 12. An optical information recording layer including a translucent reflective film having a predetermined reflectance for a reproduction light beam and a predetermined transmittance in a visible light region is provided on one surface of an optical disk substrate. Forming a first optical disk substrate and a second optical disk substrate, respectively; and providing visual information on at least one of the optical information recording layers of the first optical disk substrate and the second optical disk substrate. A step of forming a printed layer, and a step of bonding the first optical disk substrate and the second optical disk substrate via an adhesive layer with their respective surfaces on which optical information recording layers are provided facing each other. Sequentially forming an optical disk in which the printed layer is visible through an optical disk substrate of an optical disk substrate provided with the printed layer and an optical information recording layer. Production method. 13. The method according to claim 12, wherein the printing layer is formed by an electrophotographic method. 14. The step of forming the first optical disk base and the second optical disk base, respectively, comprises: forming a protective layer for protecting the optical information recording layer on the optical information recording layer; ^{14. The} method for manufacturing an optical disk according to claim 13, comprising a step of sequentially laminating a transparent conductive film having a surface electric resistance of 1 × 10 ⁻¹² Ω or less and formed of a transparent conductive material having the same. 15. The method of manufacturing an optical disc according to claim 12, wherein the translucent reflection film is formed of a conductive material. 16. The step of forming the first optical disc base and the second optical disc base, respectively, comprises laminating a transparent conductive film made of a transparent conductive material having a predetermined transmittance on the semi-transparent reflective film. 14. The method for manufacturing an optical disk according to claim 13, comprising a step, wherein the translucent reflective film is formed of a non-conductive material.