JP3175738B2 - Optical disc and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonded optical disk capable of simultaneously viewing information signal tracks and "watermarks" from the reproduction surface side of the disk, and a method of manufacturing the same.

[0002]

2. Description of the Related Art An optical disk has a large amount of recorded information,
Due to the simplicity of handling, it is widely used. In recent years, counterfeit products have been on the market for compact discs (CDs) that record information on one surface (information signal recording surface) of a single plate and reproduce information from the other surface (reproducing surface side). The industry is heavily involved in anti-counterfeiting development. A bonded optical disc has been recently developed to prevent such forgery and to increase the recording amount. In such new bonded optical discs such as a digital versatile disc (DVD), forgery prevention development will continue, but there is no effective means. Among them, in a single-plate optical disk, forgery is prevented by, for example, forming an uneven step directly on the information signal recording surface (for example, Japanese Patent Laid-Open No. 177739/1984).

[0003]

However, in the above-described forgery prevention method, since the uneven steps for preventing forgery are formed directly on the information signal recording surface, it is necessary to duplicate the veneer in this state. Thus, it is possible to easily create a forged replica with an irregular step for preventing forgery. Therefore, such a method of preventing forgery has a drawback that countermeasures for preventing forgery are extremely weak. The present invention
An optical disk using a “watermark pattern” that eliminates these drawbacks and has an anti-counterfeiting effect that disappears when the disk is forged without causing physical unevenness directly on the information signal recording surface and its It is intended to provide a manufacturing method.

[0004]

In order to solve the above-mentioned problems, the present invention provides an optical disk having the following constitutions (1) to (6) and a method of manufacturing the same.

(1) An optical disk manufacturing method for manufacturing an optical disk in which a reflective layer, an adhesive layer, and a dummy transparent substrate are sequentially laminated on an information signal recording surface of a transparent substrate, wherein one side of the dummy transparent substrate After printing a mask layer having a specific shape and a light-shielding property, on the information signal recording surface of the transparent substrate, after sequentially disposing the reflective layer, the adhesive layer, the dummy transparent substrate, from the dummy transparent substrate side Irradiating electromagnetic radiation to cure the adhesive layer, depending on the specific shape of the mask layer, by changing the irradiation amount of the electromagnetic radiation to the adhesive layer, to change the curing speed of the adhesive layer, A method for manufacturing an optical disk, comprising: displacing the reflective layer according to a difference in curing speed. (2) An optical disk in which a reflective layer, an adhesive layer, and a dummy transparent substrate are sequentially laminated on an information signal recording surface of a transparent substrate, and one surface side of the dummy transparent substrate has a specific shape and a light shielding property. An optical disk, wherein a mask layer is printed, and the reflective layer is displaced according to a specific shape of the mask layer. (3) The method for manufacturing an optical disk according to claim 1, wherein after irradiating the electromagnetic radiation, a label for concealing the mask layer is printed on a surface of the dummy transparent substrate that does not face the adhesive layer. . (4) The optical disk according to claim 2, wherein a label for concealing the mask layer is printed on a surface of the dummy transparent substrate that does not face the adhesive layer. (5) A method for manufacturing an optical disc in which a reflective layer, an adhesive layer, and a dummy transparent substrate are sequentially laminated on an information signal recording surface of a transparent substrate, wherein a specific transparent substrate is provided on a surface of the dummy transparent substrate on the adhesive layer side. After forming an uneven shape and sequentially arranging the reflective layer, the adhesive layer, and the dummy transparent substrate on the information signal recording surface of the transparent substrate, an electromagnetic wave is applied to cure the adhesive layer from the dummy transparent substrate side. A method for manufacturing an optical disk, comprising irradiating radiation and displacing the reflective layer in accordance with a difference in stress generated when the adhesive layer is cured by irradiating the dummy transparent substrate with electromagnetic radiation. (6) An optical disk in which a reflective layer, an adhesive layer, and a dummy transparent substrate are sequentially laminated on an information signal recording surface of a transparent substrate, wherein the dummy transparent substrate has a specific uneven shape on the surface on the adhesive layer side. An optical disk, wherein the reflection layer has a specific shape corresponding to the specific uneven shape.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disk according to the present invention and a method for manufacturing the same will be described with reference to the drawings. Figure 1
5 is a diagram for explaining the structure of each of the optical discs A to E of the present invention, FIG. 6 is a diagram for explaining “watermark ABC” viewed from the reproduction surface side of the optical disc, and FIG. FIG. 8 is a diagram for explaining a masking light-shielding filter used in a method for manufacturing an optical disk, FIG. 8 is a diagram for explaining blue / black spectral characteristics of the filter, and FIGS. It is a figure for explaining an example.

The optical disk of the present invention is intended for a bonded optical disk. This bonded optical disk is 2
It is formed by laminating two disk single plates using an adhesive. For example, on a transparent substrate 1 having an information signal recording surface 1a on which information signal tracks formed spirally or concentrically are formed like optical disks A to E of the present invention shown in FIGS. Reflective layer 2, adhesive layer 3,
(Sheet 6), which is formed by sequentially laminating dummy transparent substrates 4 on which information signals are not recorded. The thickness x of each of the transparent substrate 1 and the dummy transparent substrate 4 is 0.6 mm. In the figure, L indicates the direction in which the reproduction laser light is incident.

In the optical disks A and B, the stress of the adhesive used in the process of forming the adhesive layer 3 (the process of bonding the disks) is distributed, and the original position of the reflective layer 2 is slightly displaced accordingly. Thus, the "watermark pattern" is recorded on the reflection layer 2 other than the information signal recording surface 1a by the distribution of the displacement. FIG.
In the middle, the adhesive layers 3a and 3b in the adhesive layer 3 have different stresses from each other. Then, the stress corresponding to the watermark pattern of the light shielding filter 11 shown in FIG. 9 and the printed pattern 5a shown in FIG. 2 is present in the adhesive layer portion 3b. In order to give a distribution to the stress of the adhesive, for example, a difference in the curing speed of the adhesive forming the adhesive layer 3 is used. On the other hand, optical discs C ~
In E, a position corresponding to the watermark pattern (adhesive layer portion 3b)
This watermark pattern is recorded by slightly displacing the reflective layer 2 in contact with the surface from the position where it is in close contact with the information signal recording surface 1a to the adhesive layer side. Here, the strength of the bonding pressure applied to the adhesive is used.

When viewed from the reproduction surface side of the transparent substrate 1, the optical discs A and B having such a structure include a portion of the reflective layer 2 at a position corresponding to the "watermark pattern" (a position in contact with the adhesive layer portion 3b), The portion of the reflective layer 2 that is not at the position corresponding to the “watermark pattern” (the position in contact with the adhesive layer portion 3a)
The light L incident on the transparent substrate 1 from the reproduction surface side is reflected by the reflection layer 2.
When the light is reflected from the surface, the phase of the reflected light reflected from each part is different, and a phase difference occurs.
With this phase difference, the “watermark pattern” can be made visible. In the above description, the portion corresponding to the "watermark pattern" is described as the portion of the reflective layer 2 which is in contact with the adhesive layer portion 3b. On the contrary, the portion corresponding to the watermark pattern is corresponding to the adhesive layer portion 3a. Needless to say, it may be the portion of the reflective layer 2 that is in contact.

The method for manufacturing an optical disk according to the present invention is performed as follows. The bonded optical disk is manufactured by bonding two single disks using an adhesive. As this bonding method, there are several types of bonding methods depending on a method of applying an adhesive to a bonding surface of two disk single plates.

The basic one is called a "hot melt coating method", in which vinyl acetate resin or ethylene vinyl acetate resin whose viscosity has been reduced at a high temperature is applied to the bonding surface of two discs to be bonded. This is a method of applying using a roll, in which the two disks are immediately bonded after the adhesive is applied, pressure is left for a while, and the two disk single plates are bonded to each other.

Next, in the "spin bonding method", one of two discs to be bonded is placed on a spin table of a spinner, and while being rotated, electromagnetic radiation such as an ultraviolet curable resin is placed on the single disc. Drop the liquid resin that cures with, then put another disk veneer on the UV curable resin, wait for the UV curable resin to spread properly between the two disk veneers, and rotate the spin table at high speed After spreading the ultraviolet curable resin between the two disk veneers in the bonding surface of the two disk veneers,
This is a method of irradiating ultraviolet rays to cure the ultraviolet-curable resin and bonding them.

[0013] Further, the "sheet bonding method" is a method of bonding two disk single plates using a double-sided pressure-sensitive adhesive sheet. In general, a method is used in which a single disk is stacked on top of this, and pressure is applied to bond the disk to prevent air bubbles from entering the bonding surface.

According to the present invention, when used in such a laminating step of laminating two disk veneers, the stress of the adhesive is distributed (according to the curing speed of the ultraviolet curable resin) to form a watermark pattern. It is characterized by the following.
According to the present invention, the watermark pattern generated by the present method is particularly effective for, for example, a forgery method in which an information signal of a disk is directly copied. In other words, this is in contrast to the conventional countermeasures against counterfeit counterfeiting in which a conventional one causes a step on the information recording surface. According to the method of the present invention, forgery by a replica can be completely prevented since there is no bump on the information recording surface.

Next, the method for manufacturing an optical disk according to the present invention will be specifically described. First, the mechanism when the "spin bonding method" is used will be described. In the “spin bonding method”, a method of generating a stress distribution in the adhesive may be such that the curing speed when an electromagnetic radiation polymerizable resin such as an ultraviolet curable resin is cured is different in the plane of the disk. This can be achieved by making the light irradiation intensity different in the disk surface.

Specifically, as shown in FIG. 9, when the transparent substrate 1 and the dummy transparent substrate 4 are bonded and cured,
A light-shielding filter 1 that appropriately shields ultraviolet light between an ultraviolet irradiation device 10 having an ultraviolet lamp and a dummy transparent substrate 4 so that light intensity is generated in the bonded surface.
This can be achieved by inserting 1. The light shielding filter 11 used here is a mask for shielding a specific shape from light, and the specific shape includes a mark,
Pictures, characters, symbols, numbers, etc. If these "watermarks" are written using light-shielding ink, the transparent substrate 1,
The curing speed of the ultraviolet curable resin (adhesive) in the plane where the dummy transparent substrate 4 is bonded differs depending on the part without light shielding and the part with light shielding.

Thus, a stress distribution occurs in the bonding surface, and the difference in the stress causes a slight displacement of the reflection film (reflection layer 2) of the disk from the original position to the adhesive layer 3 side. When the result of such a phenomenon is viewed from the reproduction surface side or label surface side of the optical disc A, a “watermark pattern” can be visually observed. As shown in FIG. 8, the spectral characteristics of the light-shielding filter 11 are achieved by using, for example, a light-shielding filter having a light transmittance of about 10% at a wavelength of 450 nm or less. At this time, the serial number 1 is displayed on the light shielding filter 11.
If 1a can be sequentially printed with light-shielding ink, a different number (product number) for each optical disc A
Can be formed and recorded. This makes it very convenient for optical disk production management and inventory management. The optical disk A shown in FIG. 1 was manufactured in this manner.

As another manufacturing method, as shown in FIG. 10, when the transparent substrate 1 and the dummy transparent substrate 4 are bonded together and cured, an information signal generally used for bonding is called a dummy disk. A “watermark pattern” such as a mark, a picture, a character, a symbol, or a number is applied to the front surface (the surface on the label surface side) of the dummy transparent disk 4 having no surface or the back surface (the surface facing the adhesive layer 3) by shading ink. A printed material, that is, a light shielding member for shielding a specific shape from light may be attached. Ink marks 5 are generally used for “watermark patterns” such as marks, pictures, characters, symbols, and numbers. The ink 5 has a different spectral characteristic for each color, and therefore has a different transmittance of ultraviolet light. For the same reason as described above, ultraviolet light is applied between the ultraviolet irradiation device 10 and the dummy transparent substrate 4. Since the light-shielding ink 5 for appropriately shielding is inserted, a “watermark pattern” can be formed in the optical disc B. In this case, the marks, pictures, characters, symbols, numbers, and the like 5a that are the basis of the “watermark pattern” printed on the dummy transparent substrate 4 are concealed after the transparent substrate 1 and the dummy transparent substrate 4 are bonded and cured. Preferably, this can be achieved in a general post-label printing process. FIG. 2 shows a mark,
The optical disc B is in a state before the pictures, characters, symbols, numbers, and the like 5a are hidden in this manner. It was made in this way,
These are the optical discs B and C shown in FIGS.

What has been described above is a method of generating a stress distribution in an ultraviolet curable resin (adhesive) in the "spin bonding method". Next, the "sheet bonding method" (screen printing) will be described. Also in the bonding method, a stress distribution is generated by using an ultraviolet curable resin as an adhesive, as described above. Hereinafter, this “sheet bonding method” (screen printing bonding method) will be described.

Specifically, as shown in FIG. 11, on the back surface of the dummy transparent substrate 4 (the surface facing the adhesive layer 3), there is provided a watermark pattern such as a mark, a picture, a character, a symbol, or a numeral. By changing the stress of the adhesive layer 3 by the unevenness 4a, 4b formed in advance, a watermark pattern can be generated. When the smooth back surface of the dummy substrate 4 is in contact with the adhesive layer 3, the thickness of the adhesive is uniform and the stress of the adhesive is substantially uniform. However, if the irregularities 4a and 4b are present on the back surface of the dummy substrate 4 to be bonded as described above, the irregularities 4a and 4b can be visually observed as a watermark pattern from the reproduction surface side of the transparent substrate 1 via the adhesive layer 3 and the reflective layer 2. Can be. The optical disk D shown in FIG. 4 was manufactured in this manner.

As another method, as described above, on the back surface of the dummy substrate 4 (the surface facing the adhesive layer 3), corresponding to the "watermark pattern" such as a mark, a picture, a character, a symbol, or a numeral. Without forming the previously formed irregularities 4a and 4b, the sheet 6 on which the watermark pattern such as a picture or a character is cut out, or the irregularities 6a and 6b are printed, is attached to the back surface of the dummy transparent substrate 4 having both surfaces smooth and an adhesive layer. 3 has the same effect. By doing so, the dummy transparent substrate 4
Even if the upper unevenness 4a, 4b is not provided, the same effect as the case where the unevenness 4a, 4b on the dummy substrate 4 is provided can be obtained. When printing the irregularities 6a and 6b on the sheet 6, the screen printing method or the like that can sufficiently raise the printing ink thickness is desirable. The optical disk E shown in FIG. 5 was manufactured in this manner.

Now, the optical discs A to E manufactured by the above-described manufacturing method and having the "watermark pattern" recorded thereon.
It is indispensable to obtain the same reproduction characteristics as in the case of reproducing an ordinary optical disc such as a DVD in which no watermark pattern is recorded, when each of them is reproduced. Next, as an example of such reproduction characteristics, confirmation of a focus error amount of the optical head of the reproducing device will be described.

In general, such a “watermark pattern” is formed by, when viewed from the reproduction surface side of the optical disk, the optical information in the disk (the reproduction signal obtained by reproducing the information recorded on the information signal recording surface 1a) is bonded. It is observed that the reflection film (reflection layer 2) is slightly distorted due to the stress distribution in the layer 3 and is distorted. This distortion is caused by the fact that information to be correctly reproduced during reproduction of the disk
Although it causes information defects due to the distortion of the surface of
With this optical head, the "watermark pattern" should be set to a level at which the "watermark pattern" can be visually confirmed within the range in which the original information signal is correctly reproduced. If this balance is incorrect, the "watermark pattern" causes a focus error in the optical head, and the optical head has a drawback that reproduction becomes impossible.

Now, the optical disk of the present invention will be described more specifically with reference to an embodiment. The transparent substrate 1 has a thickness of 0.6 mm and a diameter of 120 m.
m, the information signal recording surface 1a is provided with a spiral or concentrically formed information signal track having a concavo-convex pit having a track pitch of 0.74 μm and a minimum pit length of 0.4 μm. The substrate 1 was manufactured by injection molding using a polycarbonate resin. A dummy transparent substrate 4 having the same thickness and diameter as the transparent substrate 1 and having a flat surface having no pits on its surface was prepared.
A reflective layer 2 having a thickness of 60 nm was formed on the surface of the information signal recording surface a of the transparent substrate 1 by vacuum film formation using aluminum.

On a spin table, a reflective layer 2
Was mounted with the reflective layer 2 facing upward. On this reflective layer 2, 3 ml of an ultraviolet curable resin was dropped on the circumference. UV-curable resin is used as the reflective layer 2 of the transparent substrate 1
After spreading to an appropriate size above, the dummy transparent substrate 4 is
Care was taken so as not to generate air bubbles, the film was superimposed on the ultraviolet curable resin and bonded to the transparent substrate 1, and the spinner was rotated so that the desired thickness of the ultraviolet curable resin layer (adhesive layer) 3 was obtained. Since the bonded transparent substrate 1 and dummy transparent substrate 4 have not yet been cured with the ultraviolet curable resin, the transparent substrate 1 and dummy transparent substrate 4 were taken out of the spinner with care so as not to be displaced from each other.

The light-blocking filter 11 was placed on the label-side surface of the dummy transparent substrate 4 thus bonded.
The light-blocking filter 11 was created as follows. Thickness 1
A 00 μm polyethylene terephthalate resin film (PET film) was cut out to a diameter of 120 mm, and “ABC” marks as shown in FIG. 7 were written thereon with black light-shielding ink. In the same manner, the test was performed with a blue light-shielding ink. Blue is written below black. That is, the marks “ABC” were written in two colors of blue and black with the center holes 13 of the optical disks A to E shown in FIG. 6 being symmetrical.

The light-shielding filter 1 is attached to the transparent substrate 1 and the dummy transparent substrate 4 bonded together before the ultraviolet curable resin is cured.
1 was mounted thereon, and ultraviolet rays were irradiated using an ultraviolet ray irradiating apparatus 10 as a lamp for curing ultraviolet rays, thereby curing the resin on the bonding surfaces of the substrates 1 and 4. UV curable resin (adhesive) during curing
Due to the shrinkage, a stress distribution was generated in the disk bonding surface (between the reflective layer 2 and the adhesive layer 3), and as a result, the position of the reflective layer 2 was displaced to form the above-mentioned “watermark pattern”.

When this disc was played on a DVD player and played back, the portion written in black on the light-shielding filter 11 was clearly visible as a “watermark pattern”. In this case, although the output waveform of the optical reproduction signal was slightly disturbed, the level was not at a level that would cause a great problem in reproduction in practical use. The part written in blue on the light-blocking filter 11 was not as clearly visible as the part written in black on the "watermark pattern", but the "watermark pattern" itself could be visually confirmed. Also in this case, the reproduction waveform of the optical reproduction signal output was not disturbed, and the reproduction was normal.

When the transparent substrate 1 and the dummy transparent substrate 4 of this disk were separated into two and the information signal recording surface 1a of the substrate 1 was copied, the "watermark pattern" on the optical disk had disappeared. . Also, when the reproduction waveform of this optical disk was input to the optical modulator of a cutting machine, cutting was performed, and a duplicate of the optical disk was created in a normal optical disk manufacturing process, the watermark pattern disappeared. It was confirmed that the "watermark pattern" could not be copied.

[0030]

The optical disk of the present invention having the above-described structure has
This is recorded by displacing a minute position from the original position of the reflective layer according to a specific shape, for example, a "watermark pattern", without causing physical unevenness directly on the information signal recording surface. did. As a result, even if the information signal recording surface on the transparent substrate is unduly duplicated, even if the two bonded substrates are peeled off, the stress between the adhesive layer and the reflective layer collapses. The “watermark pattern” that was there disappears. Since no "watermark" is recorded on the duplicated disc, it is easy to determine whether the disc is authentic or not, and the purchaser can confirm that the disc is an authentic disc before playing this disc,
Since it is possible to prevent an attempt to create a counterfeit product using the present disk, it is extremely effective in preventing counterfeiting of the disk.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the structure of an optical disc A of the present invention.

FIG. 2 is a diagram for explaining the structure of an optical disc B of the present invention.

FIG. 3 is a diagram for explaining the structure of an optical disc C of the present invention.

FIG. 4 is a diagram for explaining the structure of an optical disc D of the present invention.

FIG. 5 is a diagram for explaining the structure of an optical disc E of the present invention.

FIG. 6 shows a “watermark pattern A” viewed from the reproduction surface side of an optical disc.
It is a figure for explaining "BC".

FIG. 7 is a diagram for explaining a masking filter used in the method of manufacturing an optical disc according to the present invention.

FIG. 8 is a diagram for explaining blue / black spectral characteristics of a filter.

FIG. 9 is a diagram for explaining an embodiment of a method of manufacturing an optical disc according to the present invention.

FIG. 10 is a diagram for explaining an embodiment of a method of manufacturing an optical disc according to the present invention.

FIG. 11 is a diagram for explaining an embodiment of a method of manufacturing an optical disc according to the present invention.

[Explanation of symbols]

 A to E optical disk 1 transparent substrate 1a information signal recording surface 2 reflection layer 3 adhesive layer 4 dummy transparent substrate 6 sheet (mask layer) 11 light shielding filter

Claims (6)

(57) [Claims] A reflective layer on the information signal recording surface of the transparent substrate;
An optical disc manufacturing method for manufacturing an optical disc in which an adhesive layer and a dummy transparent substrate are sequentially laminated, wherein a mask layer having a specific shape and a light shielding property is printed on one surface side of the dummy transparent substrate, After sequentially arranging the reflective layer, the adhesive layer, and the dummy transparent substrate on the information signal recording surface, irradiating electromagnetic radiation to cure the adhesive layer from the dummy transparent substrate side, identifying the mask layer By changing the irradiation amount of the electromagnetic radiation to the adhesive layer, the curing speed of the adhesive layer is changed, and the reflecting layer is displaced in accordance with the difference in the curing speed. An optical disc manufacturing method. 2. A reflecting layer on an information signal recording surface of a transparent substrate.
An optical disc in which an adhesive layer and a dummy transparent substrate are sequentially laminated, and a mask layer having a specific shape and a light-shielding property is printed on one surface side of the dummy transparent substrate. An optical disc, wherein the reflection layer is displaced accordingly. 3. A label for concealing the mask layer is printed on the side of the dummy transparent substrate that does not face the adhesive layer after irradiating the electromagnetic radiation.
3. The method for manufacturing an optical disk according to claim 1. 4. The optical disk according to claim 2, wherein a label for concealing the mask layer is printed on a surface of the dummy transparent substrate that does not face the adhesive layer. 5. A reflective layer on an information signal recording surface of a transparent substrate.
An optical disc manufacturing method in which an adhesive layer and a dummy transparent substrate are sequentially laminated, wherein a specific uneven shape is formed on a surface of the dummy transparent substrate on the adhesive layer side, and on an information signal recording surface of the transparent substrate. After sequentially arranging the reflective layer, the adhesive layer, and the dummy transparent substrate, irradiating the dummy transparent substrate with electromagnetic radiation to cure the adhesive layer from the dummy transparent substrate side, and irradiating the dummy transparent substrate with electromagnetic radiation. A method for manufacturing an optical disk, characterized in that the reflecting layer is displaced in accordance with a difference in stress generated when the adhesive layer is cured. 6. A reflective layer on an information signal recording surface of a transparent substrate.
An optical disc in which an adhesive layer and a dummy transparent substrate are sequentially laminated, wherein the dummy transparent substrate has a specific uneven shape on a surface on the adhesive layer side, and the reflective layer conforms to the specific uneven shape. An optical disc having a specific shape.