JPH1139723A - Optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk which maintains sufficient S/N as a reproduced signal and contributes to an improvement in the visibility of the label display of a printing layer. SOLUTION: This optical disk is constituted to include an optical disk substrate 1a which has prescribed transparency and is formed with pits constituting signal information on one side, a translucent reflection film 2a which is formed on the surface side formed with these pits on the optical disk substrate la and has prescribed reflectivity and transmittance and the printing layer 4a which is formed on the surface side of this translucent reflection film 2a on the side opposite to the optical disk substrate la and is subjected to printing. The ray reflectivity of the translucent reflection film 2a is specified to >=20% from a wavelength 630 nm to 780 nm of rays and to <=30% from a wavelength 400 nm to 500 nm of the rays.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk which is an optical information recording medium, and more particularly to an optical disk having a print layer for displaying recorded information contents and the like.

[0002]

2. Description of the Related Art Conventionally, an optical disc is provided with a printed layer displaying visual information such as symbols and symbols (hereinafter referred to as "label") so that the recorded information can be perceived. Is common. 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 print layer is provided, and label display can be performed 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 that could be displayed on a label 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 disk of a double-sided recording / reproducing format, the optical information recording layer has a predetermined transparency, and the optical information recording layer, the semi-transparent reflective film and the protective layer are arranged from the optical disk substrate side of each optical disk substrate, which is the information signal read surface. There is disclosed an apparatus in which a printed layer can be visually recognized through the medium.

According to such a configuration, even with an optical disk of a double-sided recording / reproducing type, it is possible to secure a wide area for label display without obstructing reading of an information signal.

[0005]

However, since the above-mentioned translucent reflective film has a transparency of about 50%, when Al which is usually used is used for the translucent reflective film, the translucent reflective film such as CD or DVD is not used. Reproduction by the player and visual recognition of the label display were both difficult. Further, in general, when the label display of the print layer is visually recognized through the translucent reflective film, visible light passing through the translucent reflective film is attenuated, and it is difficult to obtain sufficient contrast. There is a problem that the contrast is further reduced due to the reflection due to the reflection of the visible light and the irregular reflection due to the pits, and the visibility is not always good.

The present invention has been made in view of such a conventional problem.
An object of the present invention is to provide an optical disk capable of maintaining a sufficient S / N as a reproduction signal and improving the visibility of label display on a print layer.

[0007]

For this purpose, an optical disk according to claim 1 of the present invention has an optical disk substrate having a predetermined transparency and a pit for forming signal information on one side, and the pit of the optical disk substrate. A semi-transparent reflective film having a predetermined reflectance and transmittance formed on the surface side on which is formed, and formed and printed on a surface side of the semi-transparent reflective film opposite to the optical disk substrate side surface In the optical disk including the printing layer, the light reflectance of the translucent reflection film is 20 when the light wavelength is 630 nm to 780 nm.
% And 30% or less between 400 nm and 500 nm.

According to such a configuration, the incident light beam for reproduction passes through the optical disk substrate and the translucent reflective film and reaches the print layer, and the light reflectance of the translucent reflective film has a wavelength required for a reproduced signal. 2 from 630nm to 780nm
The visible light that is reflected and incident at 0% or more is in a wavelength range of 400 nm to 500 nm necessary for visual information recognition.
At 30% or less.

In the optical disk according to a second aspect of the present invention, the translucent reflective film and the printed layer are in contact with each other. According to this configuration, since the translucent reflective film and the printing layer are disposed adjacent to each other, there is no layer interposed therebetween, and the incident light is printed directly when transmitted through the translucent reflective film. Reach the layer.

An optical disc according to a third aspect of the present invention is such that an optical buffer layer made of a transparent resin is interposed between the translucent reflective film and the print layer. According to this configuration, the incident light is transmitted through the translucent reflective film and the optical buffer layer in this order, and reaches the print layer. The optical disc according to claim 4 of the present invention, wherein the light reflectance of the translucent reflective film is 63
25% or more and 70% or less between 0 nm and 780 nm,
In addition, it is not more than 25% between the wavelengths of light of 400 nm and 500 nm.

According to such a configuration, the incident light beam for reproduction passes through the optical disk substrate and the translucent reflection film and reaches the print layer, and the light reflectance of the translucent reflection film has a wavelength required for a reproduction signal. 2 from 630nm to 780nm
The visible light which is reflected at 5% or more and 70% or less and is incident is reflected at 25% or less in a wavelength range of 400 nm to 500 nm necessary for visual recognition of visible information.

According to a fifth aspect of the present invention, in the optical disk, the translucent reflective film is made of Au, Cu, or an alloy mainly containing at least one of these elements.
According to such a configuration, the translucent reflective film in the optical disc according to any one of claims 1 to 4 is made of Au, Cu, or an alloy mainly containing at least one of these elements.

According to a sixth aspect of the present invention, in the optical disk according to the first aspect, the printing layer has a first layer on which visible information is formed by mirror image printing.
It is configured to include a printing layer and a second printing layer that forms a ground color, and as shown in the optical disc according to claim 7, the second printing layer covers the entire printing area in the printing layer. It may be formed by solid printing covering with a single color.

According to this structure, the print layer is divided into the first print layer and the second print layer, and the back color by label display or solid printing applied thereto is synthesized and visually recognized. Will be done. An optical disk according to an eighth aspect of the present invention uses two optical disks according to any one of the first to seventh aspects, each of which serves as a first optical disk base and a second optical disk base. The printing layer and the printing layer of the second optical disc base are joined. Further, a joint between the first optical disc base and the second optical disc base may be joined by an opaque adhesive.

According to this configuration, the same operation as that of the optical disk according to the first to seventh aspects is achieved also in an optical disk of a double-sided recording / reproducing type in which pits forming signal information are formed on both sides.

[0016]

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 structure of the optical disc of the present invention. On the upper surface of the transparent disk-shaped optical disk substrate 1a, there are provided grooves (hereinafter referred to as "pits") for forming a concavo-convex pattern corresponding to recorded information. A translucent reflective film 2a having a predetermined transmittance in the visible light region is formed.

On the upper surface of the translucent reflection film 2a, there is provided an optical buffer layer 3a made of a cured transparent resin, preferably an acrylic UV-curable resin. Incidentally, a structure in which the translucent reflective film 2a is directly contacted with a printing layer 4a described later may be employed without forming the optical buffer layer 3a. Further, a printing layer 4a on which a label display is printed is provided on the optical buffer layer 3a. The printing layer 4a includes a first printing layer 4aa on which visible information is printed by mirror image printing, and a printing layer 4a. And a second print layer 4ab on which the print area is covered with a single color and which is solid printed to be the background color of the label display.

The optical disk having the above-described structure is of a single-sided recording / reproducing type having an optical disk substrate 1a only on one side layer. The present invention is based on a double-sided optical disk substrate having optical disk substrates on both sides as shown in FIG. The present invention can also be applied to a recording / reproducing optical disk. Such an optical disk includes an optical disk substrate 1a, a translucent reflection film 2a, an optical buffer layer 3a,
A first optical disc substrate 6a having a printed layer 4a, an optical disc substrate 1b, a translucent reflective film 2b, an optical buffer layer 3b, and a second optical disc substrate 6b having a printed layer 4b are provided. The first optical disc substrate 6a and the second
The optical disk base 6b is integrated with the optical disk base 6b.

Further, the first optical disc base 6a and the second
The bonding between the optical disk substrate 6b and the printing layer 4a and the printing layer 4
This is performed by interposing an adhesive layer 5 made of an opaque adhesive between the layers b. 3 (A) to 3 (D) are cross-sectional views showing steps of manufacturing the double-sided recording / reproducing optical disk shown in FIG.

First, as shown in FIG. 3A, the optical disk substrate 1a of the above-mentioned first optical disk base 6a uses a stamper having a concavo-convex pattern on the surface opposite to the recorded information, and is made of polycarbonate or polymethyl. It is formed by injection molding a transparent synthetic resin such as methacrylate. Next, as shown in FIG. 3B, a translucent reflective film 2a is formed on the surface of the optical disk substrate 1a on which the concave / convex pattern is formed by using Au,
A conductive material selected from Cu or an alloy containing at least one of these elements as a main component. The light reflectance is adjusted by adjusting the thickness by using a sputtering method, a vacuum evaporation method, or the like. Wavelength between 630 nm and 780 nm
%, Preferably 25% or more and 70% or less, and 30% or less, preferably 25% or less between 400 nm and 500 nm.

Then, on the translucent reflection film 2a, FIG.
As shown in (C), the optical buffer layer 3a, the first print layer 4aa of the print layer 4a, and the second print layer 4ab are formed in this order. The optical buffer layer 3a can improve the signal reproduction characteristics of the optical disk, and can also serve as a protective film for the translucent reflective film 2a. Labels are printed on the printing layer 4a by various printing methods such as screen printing, offset printing, and pad printing. Of these, the first print layer 4aa is printed in a single color or multi-color by mirror image printing, and the second print layer 4ab is printed by a so-called solid print that covers the print area with a single color, thereby reducing the time and effort required for plate alignment and the like. Is reduced.

The first optical disk substrate 6a obtained by the above process may be of a CD standard using an optical disk substrate having a thickness of 1.2 mm, or the first optical disk substrate 6a using an optical disk substrate having a thickness of 0.6 mm. Alternatively, the second optical disk substrate 6b may be bonded to conform to the DVD standard. When the optical disc to be manufactured conforms to the DVD standard, FIG.
As shown in (D), an adhesive layer 5 made of an opaque adhesive is formed on the second print layer 4ab, and a second optical disk base 6b is formed.
And the second print layer 4bb.

In this case, the first optical disk base 6a and the second optical disk base 6b may be substantially the same or different. For example, although the optical buffer layer 3a is provided on the first optical disk substrate 6a, the optical buffer layer 3a may not be provided on the second optical disk substrate 6b. May be different.

When the adhesive layer 5 is formed, since the adhesive layer 5 is made of an opaque adhesive, it is possible to prevent color mixing with the back surface without providing the second print layers 4ab and 4bb. it can.

[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.

On the signal transfer surface of the substrate, a sputtering power (Balzas CDI-911) was used, and the input power was 0.8 kW.
Under the conditions of a sputtering time of 2.7 seconds, a translucent reflective film of Au was obtained. An integrating sphere was mounted on a spectrophotometer (U-3120, manufactured by Hitachi, Ltd.), and the total reflectance of this translucent reflective film was measured from the side of the substrate. The maximum reflectance between wavelengths 400 to 500 nm was 17%. The minimum reflectance between wavelengths 630 and 780 nm was 40%, and the maximum reflectance was 52%.

An acrylic resin (SO
NY Chemical Co., Ltd., SK5000) was applied by a spin coating method, and was cured by irradiation with ultraviolet light to form an optical buffer layer having a thickness of 7 μm. Using an ultraviolet curable black ink (Dainippon Ink Die Cure 582), a design including full-width and quarter-width characters was mirror-image-printed on the optical buffer layer by a screen printer and cured by ultraviolet irradiation.

Next, after performing solid printing with a screen printing machine using a white ultraviolet curable ink (Dainippon Ink Die Cure 583), the solid is cured by irradiating ultraviolet light to obtain a first optical disk base. Two optical disk substrates were obtained. Then, a hot-melt adhesive was applied on the printed layers of the first optical disk substrate and the second optical disk substrate, respectively, and the adhesives were overlapped and pressed to join them.

Here, when the design was viewed from each substrate side, the details of the design including the quarter-quarter characters could be clearly read (design visibility = 視 認; see Table 1). Subsequently, when played on a commercially available DVD player, both sides could be reproduced without any problem (player reproduction; see Table 1). Example 2 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.

Examples 3 and 4 Optical disks were prepared in the same manner as in Examples 1 and 2, except that the optical buffer layer was not provided. Table 1 shows the evaluation results. [Examples 5 and 6] Optical disks were prepared in the same manner as in Example 1 except that Cu was used for the translucent reflective film and the sputtering conditions were changed. Table 1 shows the evaluation results.

Examples 7 and 8 Optical disks were prepared in the same manner as in Examples 5 and 6, except that the optical buffer layer was not provided. Table 1 shows the evaluation results. Example 9 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 1.2 mm.

A single-sided optical disk was obtained by providing a translucent reflective film, an optical buffer layer and a printing layer in the same manner as in Example 1 except that the sputtering conditions were changed. When the design was visually observed from the substrate side, the design including the characters excluding the quarter-quarter characters could be read. Table 1 shows the evaluation results. Example 10 An optical disk was prepared in the same manner as in Example 9, except that Cu was used for the translucent reflective film and the sputtering conditions were changed. Table 1 shows the evaluation results.

[Comparative Examples 1 to 6] Optical disks were obtained in the same manner as in Example 1, while changing the material of the translucent reflective film and the sputtering conditions. Table 1 shows the evaluation results.

[0034]

[Table 1]

As can be seen from the evaluation results in Table 1, in all of Examples 1 to 10, design visibility = ○ (characters are difficult to read, but design identification is possible) or ◎ (design, full-width characters, / 4 characters are legible), player reproduction = （(time is required for disc recognition, but sound and image are good) or ◎ (both disc recognition and sound and image are good).

[0036]

As described above, according to the first aspect of the present invention, by maintaining a sufficient S / N for the reproduced signal, it is possible to maintain a sufficient S / N for the reproduced signal, and at the same time, the label of the print layer. The visibility of the display can be improved. According to the second aspect of the present invention, since the translucent reflective film and the printing layer are disposed in contact with each other, the attenuation of incident light is reduced as compared with the case where an intervening layer exists between them. Can be suppressed.

According to the third aspect of the present invention, the irregular reflection component of the reproduction light transmitted through the translucent film is reduced, and the irregular reflection component from the interface of the printing layer and the surface of the pigment printed on the printing layer is picked up. , And the signal reproduction characteristics can be significantly improved. According to the invention of claim 4, the effect of the invention of claim 2 or 3 can be further improved.

According to the fifth aspect of the invention, the effects of the first to fourth aspects of the invention can be further improved. According to the inventions according to claims 6 and 7, since the printing layer is divided into two layers and arranged, it is possible to prevent the background color and the label display from being mixed with each other. By performing printing, it is possible to save time and effort such as plate alignment.

According to the eighth aspect of the present invention, the same effects as those of the optical disks according to the first to seventh aspects can be obtained even in an optical disk of a double-sided recording / reproducing type. According to the ninth aspect of the present invention, it is possible to prevent color mixture with a back color without providing the second print layer.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an example of a layer configuration of a single-sided recording / reproducing optical disk of the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a layer configuration of a double-sided recording / reproduction type optical disc of the present invention.

FIG. 3 is a diagram for explaining a manufacturing process of a double-sided recording / reproduction type 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 Print layer 4aa, 4ab First print layer 4ba, 4bb Second print layer 5 Adhesive layer 6a First optical disk base 6b Second Optical disk substrate

Claims (9)

[Claims] 1. An optical disk substrate having a predetermined degree of transparency and having pits for forming signal information formed on one side thereof, and a predetermined reflectance and transmittance formed on the side of the optical disk substrate on which the pits are formed. An optical disc comprising a translucent reflective film having the same, and a printed layer formed on the surface of the translucent reflective film opposite to the surface on the optical disk substrate side and subjected to printing. The light reflectance is
20% or more between 630 nm and 780 nm, and 30% between 400 nm and 500 nm.
An optical disc characterized by the following. 2. The optical disc according to claim 1, wherein the translucent reflection film and the printing layer are in contact with each other. 3. The optical disk according to claim 1, wherein an optical buffer layer made of a transparent resin is interposed between the translucent reflection film and the printing layer. 4. The light transmittance of the translucent reflection film is 25% or more and 70% or less between 630 nm and 780 nm, and 25% or less between 400 nm and 500 nm. 4. The optical disk according to claim 2, wherein: 5. The translucent reflective film according to claim 1, wherein the translucent reflective film is made of Au, Cu, or an alloy mainly containing at least one of these elements. optical disk. 6. The printing method according to claim 1, wherein the printing layer includes a first printing layer on which visible information is formed by mirror image printing, and a second printing layer for forming a ground color. 5. The optical disc according to 5. 7. The optical disk according to claim 6, wherein the second print layer is formed by solid printing that covers the entire print area of the print layer with a single color. 8. The optical disk according to claim 1, wherein the two optical disks are respectively a first optical disk substrate and a second optical disk substrate, and the printed layer and the second optical disk substrate of the first optical disk substrate. (2) An optical disk, wherein the printed layer of the optical disk substrate is joined. 9. The optical disc according to claim 8, wherein the joining portions of the printing layers are joined by an opaque adhesive.