JP2001084647A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of reproducing characteristics by applying various kinds of coloring without generating discoloring. SOLUTION: This optical recording medium has a first substrate 12 formed with a reflecting film on one side and a second substrate 13 having light transmissivity to be bonded to the side, where the reflecting film 15 is formed, on this first substrate 12, a coloring layer 20 is provided on the side of the second substrate 13 bonded to the first substrate 12, and the first and second substrates 12 and 13 are bonded by an adhesive agent having the same or almost the same refraction factor as the coloring layer 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium formed by bonding first and second substrates,
The present invention relates to a colored optical recording medium.

[0002]

2. Description of the Related Art Hitherto, as an information signal recording medium, an optical disk which records an information signal using a light beam or reads out the recorded information signal has been used.

[0003] As this type of optical disk, there are provided those which exclusively record an audio signal and those which record a video signal together with the audio signal. further,
As optical discs, there are provided one in which a program for controlling the operation of an information processing apparatus such as a computer is recorded, and one in which game software for a video game is recorded.

Further, an optical disc is provided which can record an audio signal, a video signal, or other data. Thus, the optical disk is widely used as a recording medium for various information signals.

[0005] Some optical disks used as recording media for various information signals have a common diameter and thickness, and have different recording formats for information signals while having substantially the same external appearance. Optical discs having different recording formats cannot record and / or reproduce information signals using a common recording and / or reproducing apparatus.

[0006] It is difficult to visually discriminate optical disks differing only in recording format while having a common diameter and thickness. Identification of this type of optical disc is performed after the disc is mounted on a recording and / or reproducing apparatus and an identification signal recorded on the optical disc is detected. Since identification of an optical disk is performed by being mounted on a recording and / or reproducing apparatus, a desired optical disk cannot be quickly selected.

Therefore, in order to easily identify a specific optical disk from various types of optical disks, a substrate in which a specific color is applied to a substrate constituting the disk has been provided.

[0008]

Heretofore, there has been provided a colored optical disk having a substrate formed of a synthetic resin material to which a dye such as a dye or a pigment is added. This type of substrate is formed by melting a synthetic resin material and injection-molding the melted synthetic resin material. The synthetic resin material is
When injection molding is performed, the temperature reaches approximately 250 ° C to approximately 400 ° C. When heated to such a temperature, the dye or pigment added to the synthetic resin material deteriorates, loses its function as a pigment, and cannot be colored in a desired color.

Further, the color for efficiently transmitting the light beam used for reading the information signal recorded on the optical disk is also limited, so that the selection of the color for coloring the substrate through which the light beam is transmitted is also limited. turn into.

[0010] To solve such problems. An optical disk as shown in FIG. 1 has been proposed. As shown in FIG. 1, the optical disc 1 includes first and second substrates 2 and 3 formed of synthetic resins which are bonded to each other.
On one surface side of the first substrate 2, a pit pattern 4 composed of minute unevenness corresponding to an information signal recorded on the optical disc 1 is formed. On the pit pattern 4, a reflection film 5 for reflecting a light beam incident from the second substrate 3 is applied. The reflection film 5 is formed of a metal such as aluminum, gold, or silver that can secure a high reflectance for reflecting the light beam incident on the optical disc 1 by 90% or more. The signal recording section 6 is formed by the pit pattern 4 and the reflection film 5.

On the surface of the first substrate 2 on which the reflective film 5 is formed, a second adhesive layer 7 made of an ultraviolet curable resin is interposed.
Substrates 3 are joined. On the surface facing the outside of the first substrate 2, there is provided a label printing unit 8 which shows the contents of information signals recorded on the optical disc 1.

As shown in FIG. 1, this optical disc 1
It is formed by applying and curing an ultraviolet curable resin to which a dye such as a dye or a pigment is added on the surface of the second substrate 3 on which a light beam for reading an information signal recorded in the signal recording unit 6 is incident. Colored layer 9 is provided.

Since the colored layer 9 is formed on the surface on which the light beam is incident, it is necessary to form the colored layer 9 with high precision and smoothness. For example, as shown in FIG. 2, when a defect 10 due to uneven coating or missing pigment occurs in the colored layer 9, an aberration is generated in a light beam focused on the reflective film 5 and incident thereon.
The information signal cannot be read accurately.

Further, since the colored layer 9 is formed on the surface of the optical disk 1, there is a possibility that the colored layer 9 may be missing.
In some cases, it is necessary to provide a protective layer for protecting the colored layer 9, and it is not easy to manufacture.

In order to solve the problem of the colored layer 9 being formed on the surface of the optical disk 1, as shown in FIG.
In addition, a method has been proposed in which a dye is added to the adhesive layer 7 for bonding the second substrates 2 and 3.

Since the first substrate 2 is bonded to the second substrate 3 with the surface on which the reflection film 5 is formed as a bonding surface, the adhesive layer 9 to which the dye is added comes into direct contact with the reflection film 5. Since the dye has a property of easily absorbing moisture, the moisture absorbed by the dye adversely affects the reflective film 5 formed of a metal such as aluminum. For example, as a result of the reflection film 5 floating from the pit pattern 4, the information signal cannot be read accurately.

If a dye that efficiently transmits a light beam used for reading out an information signal recorded on an optical disk without causing such moisture absorption is selected, color options are limited, and desired coloring is performed. Cannot be applied.

An object of the present invention is to provide an optical recording medium which can be reliably colored without causing discoloration or the like and can be easily manufactured.

Another object of the present invention is to provide an optical recording medium which can prevent the deterioration of a reflection film due to coloring and can accurately read an information signal.

It is still another object of the present invention to provide an optical recording medium which has more color options and can be colored with a desired color.

[0021]

In order to achieve the above object, the present invention provides a first substrate having a reflective film formed on one surface, and a reflective film formed on the first substrate. A light-transmissive second substrate joined to the surface
Providing a colored layer on the side of the bonding surface of the second substrate to the first substrate;
The first substrate and the second substrate are joined by an adhesive having the same or almost the same refractive index as the coloring layer.

Here, the colored layer is formed of an ultraviolet curable resin to which a dye is added. This colored layer is formed by uniformly spin-coating a solution in which a dye is dissolved in a solvent, spreading the solution to a uniform thickness, and volatilizing the solvent.
On this coloring layer, a protective layer for protecting the coloring layer is provided.

In the optical recording medium according to the present invention, since the colored layer provided between the first and second substrates to be joined to each other is formed without contacting the reflective film, the dye contained in the colored layer This prevents the reflective film from being adversely affected.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an optical disk will be described below.

As shown in FIG. 4, an optical disk 11 to which the present invention has been applied has a first substrate 1 bonded to each other.
2 and a second substrate 13.

The first substrate 12 is formed by molding a light-transmitting synthetic resin such as a polycarbonate resin.
On one surface side, a pit pattern 14 composed of minute unevenness corresponding to an information signal recorded on the optical disk 11 is formed. On this pit pattern 14, the second
A reflective film 15 for reflecting a light beam incident from the substrate 13 is provided. The reflection film 15 is formed of a metal such as aluminum, gold, silver, or the like that can secure a high reflectance for reflecting the light beam incident on the optical disk 11 by 90% or more. The pit pattern 14 and the reflection film 15
Thus, the signal recording section 16 is formed.

The second substrate 13 is bonded to the surface of the first substrate 12 on which the reflection film 15 is formed via an adhesive layer 17 using an ultraviolet curable resin. On the surface facing the outside of the first substrate 12, a label printing section 18 on which pictures, characters, etc. indicating the contents of information signals recorded on the optical disc 11 are printed. The surface facing the outside of the second substrate 13 is a signal recording unit 16 provided on the first substrate 12.
Is an incident surface 19 of a light beam on which a light beam for reading an information signal recorded in the light beam is incident.

Second substrate 1 bonded to first substrate 12
Numeral 3 is formed in a flat plate shape without forming a pit pattern or the like constituting a signal recording portion, and a colored layer 20 is formed on a bonding surface side to the first substrate 12. This colored layer 2
No. 0 is formed by applying a coloring agent containing a pigment of a desired color to an ultraviolet curable resin and curing the same. The colorant is applied so as to be uniform over the entire surface of the second substrate 13 by using an application method such as a spin coating method or a roll coater method.

The coloring agent used here is formed by adding a dye selected from a dye and / or a pigment to an epoxy acrylate-based ultraviolet curable resin. As a dye used here, a light beam used for reading an information signal recorded in a signal reading unit 16 provided on the optical disc 11, for example, a light beam of 630 nm to 800 nm is sufficiently transmitted and reflected by the reflection film 15. The light beam is selected such that the light beam returns 60% or more with respect to the incident light beam. Further, the dye used here is selected from dyes and / or pigments having good compatibility with the ultraviolet curable resin so that the dye can be uniformly dispersed in the colorant.

The epoxy acrylate UV-curable resin constituting the colorant is prepared by adding additives such as an acrylate monomer, an acrylate oligomer, a photoreaction initiator, and, if necessary, a sensitizer, a polymerization inhibitor and a leveling agent. Be composed.

More specifically, as the colorant used here, the epoxy acrylate-based UV curable resin constituted as described above is formed by adding a triphenolmethane-based blue dye in an amount of 1% by weight to 5% by weight. Is used. This colorant is prepared by adding a triphenolmethane-based blue dye to an acrylate-based ultraviolet-curable resin in an amount of 1% by weight or more.
After mixing at 5% by weight, it is made by filtering out the insoluble portion. This colorant is formed as a colored solution. Since the coloring agent obtained here is in the form of a solution, it can be immediately applied to the second substrate 13. The colorant formed using the ultraviolet-curable resin as a solvent is cured by irradiation with ultraviolet light to form the colored layer 20. At this time, the solvent is volatilized.

Note that a protective layer for protecting the colored layer 20 may be provided on the colored layer 20 as necessary.

The second substrate 13 on which the colored layer 20 is formed is bonded to the surface of the first substrate 12 on which the reflective film 15 is formed, using the surface on which the colored layer 20 is formed as a bonding surface. It is joined by the agent 21. The adhesive 21 has the same or almost the same refractive index as the coloring layer 20, and is a urethane acrylate-based resin of the same type as the epoxy acrylate-based UV-curable resin that is a main component of the coloring layer 20. Resin is used. This resin is composed of additives such as an acrylate monomer, an acrylate oligomer, a photoreaction initiator, and if necessary, a sensitizer, a polymerization inhibitor, a leveling agent, and the like.

The optical disk 11 configured as above is
By seeing the colored layer 20 through the second substrate 13,
It can be recognized as the color of the colored layer 20. The colored layer 20 is formed on the first and second substrates 1 bonded to each other.
Since the colored layer 20 is located between the colored layers 2 and 13, peeling of the colored layer 20 and the like are reliably prevented. Further, since the coloring layer 20 does not directly contact the reflection film 15, the coloring layer 20 does not adversely affect the reflection film 15 and the range of choice of the dye contained in the coloring layer 20 can be increased. Can be various colors.

Further, by providing the coloring layer 20 and the adhesive 21 with the same or almost the same refractive index, the provision of the coloring layer 20 allows the light beam incident on the reflection film 15 and being reflected. The information signal recorded on the signal recording unit 16 can be read out by accurately focusing the light beam on the reflective film 15 without adversely affecting the information.

Here, a state in which the first and second substrates 12 and 13 are molded will be described.

As an apparatus for molding these substrates 12 and 13, an injection molding machine as shown in FIG. 5 is used. As shown in FIG. 5, the injection molding machine includes a mold section 33 including a fixed mold 31 and a movable mold 32 on a base 30. The fixed mold 31 is mounted on a fixed platen 34 mounted on the base 30. The movable mold 32 includes the base 3
The fixed die 31 is attached to a movable plate 36 which is supported so as to approach and separate from the fixed plate 34 via a slide unit 35 provided on the fixed die 31. Movable board 36
Is supported by a tie bar 38 connecting the fixed platen 34 and the movable platen driving portion 37, and moves in a direction approaching and separating from the fixed platen 34 using the tie bar 38 as a guide. Movable board 3
On the 6th side, protruding pins for taking out the substrates 12 and 13 formed by the mold 33 from the mold portion 33 and the substrates 12 and 1
3 is provided with a movable unit 39 provided with a center hole forming pin for forming a center hole.

The injection molding machine includes a hopper 42 provided with a molding material inlet 41 into which a synthetic resin material such as a polycarbonate resin as a material of the substrates 12 and 13 molded by the molding machine is provided. A screw cylinder 43 that melts and kneads the synthetic resin material supplied from the hopper 42 and injects the synthetic resin material melted by the screw cylinder 43 into the mold part 33 from a nozzle 44 provided at the tip of the screw cylinder 43. And an injection drive unit 45 for causing the injection drive unit 45 to operate.

The screw cylinder 43 will be described in more detail. As shown in FIG. 6, the screw cylinder 43 includes a cylinder 46 provided with a heating unit (not shown).
And a screw 47 rotatably supported in the cylinder 46 and rotationally driven by the injection drive unit 45.

The screw cylinder 43 is provided with a synthetic resin material supplied into the cylinder 46 through a supply port 48 connected to the hopper 42 by rotating a screw 47 having a spiral groove 47 a formed on the outer peripheral surface. Is melted and kneaded, and the molten synthetic resin material is injected into the mold 33 via the nozzle 44 attached to the tip end of the cylinder 46.

In order to mold the first and / or second substrates 12 and 13 using the injection molding machine configured as described above,
The movable platen 36 is moved to the fixed platen 34 side, and the movable mold 32 is brought into a clamped state in which the movable mold 32 abuts against the fixed mold 31. Here, the synthetic resin material melted from the screw cylinder 43 via the nozzle 44 is injected into the mold part 33. Thereafter, the mold part 33 is cooled, and the movable plate 36 is moved in a direction away from the fixed plate 34 to move the movable mold 32 to the fixed mold 31.
First and / or second by opening the mold away from
Substrates 12 and 13 are molded.

When the first substrate 12 provided with the pit pattern 14 is molded, a stamper for molding the pit pattern 14 is attached to the fixed mold 31 side.

The first and second substrates 12 and 13 may be formed independently of each other. However, since the first and second substrates 12 and 13 are formed in one injection molding machine, respectively. By providing the above two mold parts, molding may be performed simultaneously for each pair.

In the above description, an example in which the present invention is applied to an optical disk has been described. However, the present invention is widely applied to an optical recording medium in which information signals are recorded or reproduced by using other light beams, and the optical disk described above is used. The same advantage as in the case where the present invention is applied can be obtained.

[0045]

As described above, in the optical recording medium according to the present invention, the colored layer provided between the first and second substrates joined to each other is formed without contacting the reflective film. The reflection film can be prevented from being adversely affected by the coloring matter contained in the coloring layer, and can be reliably colored without causing discoloration and the like, and the manufacturing thereof can be facilitated.

Further, since the colored layer is separated from the reflective film by the thickness of the adhesive, it is hardly affected by foreign matters such as dust and bubbles mixed in the colored layer when reproducing the information signal.
An accurate information signal can be reproduced.

Further, since the adhesive functions as a protective layer for the colored layer, it is possible to suppress the adverse effect of providing the colored layer, so that it is possible to perform coloring with a desired color. Discrimination from the medium becomes easier.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a conventional optical disc.

FIG. 2 is a cross-sectional view showing a state where a defect has occurred in the optical disc.

FIG. 3 is a cross-sectional view showing another example of a conventional optical disc.

FIG. 4 is a sectional view showing an optical disc according to the present invention.

FIG. 5 is a side view showing an injection molding machine for molding a substrate constituting the optical disc according to the present invention.

FIG. 6 is a sectional view showing a screw cylinder constituting the injection molding machine.

[Explanation of symbols]

11 optical disk, 12 first substrate, 13 second
Substrate, 15 reflective film, 20 colored layer, 21 adhesive.

Claims (3)

[Claims] A first substrate having a reflection film formed on one surface thereof; and a light-transmitting second substrate bonded to a surface of the first substrate having the reflection film formed thereon. A colored layer is provided on the side of the second substrate bonded to the first substrate, wherein the first substrate and the second substrate have the same or substantially the same refractive index as the colored layer. An optical recording medium joined by an adhesive having a specific ratio. 2. The color layer according to claim 1, wherein the color layer is formed of a UV-curable resin to which a dye is added.
The optical recording medium according to the above. 3. The coloring layer is formed by uniformly spin-coating a solution in which a dye is dissolved in a solvent, spreading the coating to a uniform thickness, and volatilizing the solvent, and protecting the coloring layer thereon. 2. The optical recording medium according to claim 1, further comprising a protective layer for performing the operation.