JPH10289482A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve excellent appearance in visual observation from transparent substrate side by interposing a buffer layer composed of a resin layer between a printed layer of the printing surface of a dummy substrate, which is stuck to an information surface of the transparent substrate to face each other, and the information layer to assimilate the difference in level caused by the printed layer. SOLUTION: An information surface 102, on which the information of music, image or the like is recorded as a bit string, is formed on one surface of the transparent substrate 101 composed of a polycarbonate resin having 0.6 mm thickness. A reflecting layer 104 is stuck thereto by sputtering aluminum. A pattern such as a disk title, a trade mark, an illustration or the like is printed on the 1st flat surface 108 of the dummy substrate composed of the polycarbonate resin having 0.6 mm thickness by gravure, off-set printing or the like. The upper surface of the reflecting layer 104 is covered with the buffer layer 105 by the spin-coating of an ultraviolet curing resin or the like. The hardness of the buffer layer 105 is setted to be in the range of HB-6B of pencil scratch test.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium in which a substrate having an information surface and a dummy substrate having no information surface are bonded to each other. The present invention relates to an optical information recording medium provided with a printing layer.

[0002]

2. Description of the Related Art A minute pit called a pit corresponding to recording information is formed on one surface of a transparent substrate, a laser beam is focused on a pit row through the transparent substrate, and recording is performed by a change in the amount of reflected laser light. A typical example of an optical disc for reproducing a medium is a CD (Compact Disc).

A CD has a diameter of 120 mm and a thickness of 1.2 mm.
A pit row having a shortest pit length of about 0.9 μm is formed at a track pitch of 1.6 μm on the transparent substrate. The linear velocity during reproduction is constant at about 1.2 to 1.4 m / s, has a recording capacity of about 650 Mbytes, and records digital data such as music and video.

[0004] A CD has a single-plate structure composed of one transparent substrate and has only one information surface. At the time of reproduction, since laser irradiation is performed through the transparent substrate, a label indicating a disc title or the like is printed on the surface of the transparent substrate opposite to the surface on which the laser light is incident.

[0005] On the other hand, DVDs (Digital Versatile Discs) whose recording density is increased to about 7 times or more of CDs are commercially available.
The DVD has been developed as a next-generation optical disk, and is a large-capacity optical disk capable of recording digitalized audio / video signals and computer data.

[0006] The DVD employs several new technologies in order to increase the information recording capacity compared to the conventional optical disk. For example, the thickness of the substrate is 0.6 mm, and the two substrates are bonded to form an optical disk having a thickness of 1.2 mm. In this case, information can be recorded on each substrate,
For example, single-sided two-layer reproduction can be performed. Playback-only D
Depending on the recording capacity and function, DVD-5, 9, 1
There are many specifications, 0 and 18. In addition, a DVD-R (DVD-Reco
rdable) and a DVD-RAM (DVD-Random Access Memory) in which information can be rewritten any number of times have been proposed.

[0007] As a read-only type DVD capable of reproducing information from one side, a DVD having only one information side is used.
There are a VD-5 and a DVD-9 capable of reproducing two information surfaces from one side. FIG. 3 is a schematic diagram showing a cross-sectional structure of a conventional DVD-5. In the figure, 301 is a transparent substrate,
302 is an information surface, 303 is a reflective layer, 304 is an adhesive layer, 3
05 is a dummy substrate, 306 is a pickup, and 307 is a laser beam.

[0008] DVD-5 has a transparent substrate 301 having a diameter of 120 mm and a thickness of 0.6 mm on which an information surface 302 is formed;
The structure is such that a dummy substrate 305 having a diameter of 120 mm and a thickness of 0.6 mm having no information surface is bonded by an adhesive layer 304 such that the information surface 302 is inside. The surface of the information surface 302 is covered with a reflective layer 303 made of a metal such as aluminum which reflects most of the laser light,
Reproduction of the recorded information is performed from one side through the transparent substrate 301 by the laser beam 307 emitted from the pickup 306.

FIG. 4 is a schematic diagram showing a cross-sectional structure of a conventional DVD-9. In the figure, 401 is a transparent substrate, 402 is a first information surface, 403 is a translucent reflective layer, 404 is a transparent resin layer, 405 is a second information surface, 406 is a reflective layer, 407 is an adhesive layer, and 408 is a dummy. Substrate, 409 is a pickup,
Reference numeral 410 denotes a laser beam. In DVD-9, diameter 1
On one surface of a transparent substrate 401 having a thickness of 20 mm and a thickness of 0.6 mm, a first information surface 402 is formed.
The surface 02 is covered with a translucent reflective layer 403 made of a dielectric material such as aluminum nitride or a metal such as gold which reflects a part of the laser beam and transmits the rest.

The surface of the translucent reflective layer 403 has a laser beam 4
A transparent resin layer 404 transparent to ten wavelengths is formed, and the second information surface 40 is formed on the surface of the transparent resin layer 404.
5 is formed by a 2P (Photo Polymerization) method. The surface of the second information surface 405 is covered with a reflective layer 406 made of a metal such as aluminum which reflects most of the laser light.

The transparent substrate 401 is bonded to a dummy substrate 408 having a diameter of 120 mm and a thickness of 0.6 mm via an adhesive layer 404 such that the first information surface 402 is on the inside. The information recorded on the first information surface 402 and the second information surface 405 is reproduced by the laser light 410 emitted from the pickup 409.
01 from one side.

In addition, DVD-Rs and DVD-RAMs, which allow users to record or rewrite information by themselves, have been developed. FIG. 5 shows a DVD-ROM having a single recording layer.
It is a schematic diagram which shows the cross-section of R. In the figure, 501 is a transparent substrate, 502 is a guide groove, 503 is a recording layer, 504 is a reflective layer, 505 is an adhesive layer, 506 is a dummy substrate, 507 is a pickup, and 508 is a laser beam.

The DVD-R includes a transparent substrate 501 on which a guide groove 502 for controlling tracking of a laser beam 508 emitted from a pickup 507 and an organic dye such as a cyanine dye formed on the guide groove 502. Recording layer 503, and a laser beam 5 formed on the recording layer 503.
08, a reflective layer 504 made of metal such as aluminum or gold, and a dummy substrate 5 having both surfaces smooth.
06, and the reflective layer 504 and the dummy substrate 506 are bonded via an adhesive layer 505. Recording of information on the DVD-R and reproduction of information from the DVD-R are performed through the transparent substrate 501 by the laser beam 508 emitted from the pickup 507.

According to the specification of DVD, the track pitch is about 0.3.
7 μm (about 0.8 μm for DVD-R), the shortest pit length is about 0.4 μm, the linear velocity during reproduction is about 3.5 m / s, and the storage capacity is about 4.7 GB on one side (DVD-R is on one side) About 3.9 GB), and the reproduction laser beam wavelength is 630-6.
60 nm.

As described above, DVD-5, DVD-9,
Since DVD-R and DVD-RAM are irradiated with laser through a single-sided transparent substrate during recording or reproduction,
A printed layer such as a label indicating a disc title or the like can be formed on the surface of the dummy substrate.

Furthermore, recently, not the surface of the dummy substrate, but the bonding surface side of the dummy substrate, that is, in the case of DVD-5 in FIG. There is a DVD having a configuration in which a print layer such as a label is formed and a label is displayed through the dummy substrate 305. A DVD having such a configuration, when combined with an optical effect caused by the thickness of the dummy substrate, the refractive index, and the like, when the label is viewed with the naked eye, when a print layer is formed on the surface of the conventional dummy substrate. In comparison, there was an effect that a glossy feeling and a high-class feeling were felt and the beauty was excellent.

[0017]

However, in a DVD having a configuration in which a printing layer such as a label is formed on the bonding surface side of the dummy substrate, a portion between the portion where the printing layer is provided and the portion where the printing layer is not provided is provided. In the case of unevenness or multilayer (multicolor) printing, a portion opposed to the unevenness due to unevenness between the printing layers, for example, the information surface of the adhesive layer 304, the reflective layer 303, and the transparent substrate 301 in the DVD-5 of FIG. 30
2 is pressed and there is a problem that deformation occurs. In particular, in a portion where characters and the like are printed, the adhesive layer 30 corresponding to the characters and the like is placed on the transparent substrate 301 from the side of the laser beam incident surface.
4. Since the deformation of the reflective layer 303 and the transparent substrate 301 can be observed with the naked eye, there is a problem that the aesthetic appearance of the disc is significantly impaired.

If there is a deformation, the reflective layer 303
There is a problem that the laser light 307 is minutely diffracted or diffused due to the laser beam 307 or a deformed portion of the information surface 302, thereby increasing the jitter of the reproduced signal.

[0019]

According to a first aspect of the present invention, there is provided a substrate provided with an information surface on which information is recorded as a pit row or a guide groove is formed on one side. And a transparent dummy substrate having a first smooth surface and a second smooth surface, wherein the first smooth surface of the dummy substrate has a printing layer and the printing layer. A buffer layer for absorbing the unevenness of the layer is formed in order, and the substrate and the dummy substrate are bonded via an adhesive layer such that the information surface and the buffer layer face each other.

According to a second aspect of the present invention, there is provided a substrate having an information surface on which information is recorded as a pit row or a guide groove is formed on one side, a first smooth surface and a second smooth surface. And a transparent dummy substrate having: a printing layer formed on the first smooth surface of the dummy substrate, and a recording layer and / or a printed layer formed on the information surface of the substrate. Alternatively, a buffer layer that absorbs unevenness due to the printing layer is formed via a reflective layer, and the substrate and the dummy substrate are bonded together via an adhesive layer such that the buffer layer and the printing layer face each other. It is a feature.

According to a third aspect of the present invention, there is provided a substrate having an information surface on which information is recorded as a pit row or a guide groove is formed on one surface, a first smooth surface and a second smooth surface. An optical information recording medium comprising: a transparent dummy substrate provided with: a printed layer formed on the first smooth surface of the dummy substrate, wherein the substrate and the dummy substrate are provided with the information surface and the printed layer. Are bonded to each other via a buffer layer that absorbs the unevenness of the printing layer so as to face each other.

According to a fourth aspect of the present invention, in the optical information recording medium according to the first or second aspect, the buffer layer has a pencil hardness ranging from HB to 6B and a thickness. The thickness is in the range of 40 μm to 100 μm.

According to a fifth aspect of the present invention, in the optical information recording medium according to the third aspect, the adhesive layer has a pencil hardness in the range of HB to 6B and a thickness of 40 μm to 40 μm. It is within a range of 100 μm.

According to the first to fifth aspects of the present invention, a buffer layer that absorbs unevenness due to the print layer formed on the bonding surface side of the dummy substrate is provided between the print layer and the adhesive layer. Since an adhesive layer is provided between the information surface of the substrate having the information surface and the print layer formed on the dummy substrate or as a buffer layer, the information on the reflective layer and the transparent substrate is formed by the unevenness of the print layer. The surface is not pressed and deformed.

[0025]

Embodiments of the optical information recording medium of the present invention will be described below in detail with reference to the drawings. FIG.
FIG. 1 is a schematic diagram showing a cross-sectional structure of an embodiment of the optical information recording medium of the present invention. In the figure, 101 is a transparent substrate, 102 is an information surface, 103 is a pit row, 104 is a reflective layer, 105 is a buffer layer, 106 is an adhesive layer, 107 is a dummy substrate, 108 is a first smooth surface, and 109 is a second , 110 indicates a printed layer. FIG. 2 is a schematic diagram showing a case where a printing layer is printed in multiple layers in one embodiment of the optical information recording medium of the present invention. In the figure, 201 is the first printing layer, 202 is the second printing layer.
The printing layer is shown, and the same parts as those in FIG. 1 are denoted by the same reference numerals.

The transparent substrate 101 is a resin substrate or a glass substrate such as a polycarbonate resin or an acrylic resin having an outer diameter of 120 mm, an inner diameter of 15 mm, and a thickness of 0.6 mm. Information surface 102 on one side. The information surface 102 of the transparent substrate 101 has a reflective layer 104 made of a metal such as gold or aluminum or an alloy thereof that reflects most of the laser light.
Covered with. The reflection layer 104 is formed by a sputtering method, an evaporation method, or the like, and preferably has a thickness in the range of 40 to 200 nm.

On the other hand, the dummy substrate 107 has an outer diameter of 120 m.
m, an inner diameter of 15 mm, a thickness of 0.6 mm, a resin substrate such as a polycarbonate resin or an acrylic resin, or a glass substrate, which does not have an information surface and has a first smooth surface 108 and a second smooth surface 109. ing. On the surface of the first smooth surface 108 of the dummy substrate 107, a print layer 110 made of characters such as a disc title, a manufacturer / seller name, and a design such as a trademark or an illustration is formed (printed).

In this case, the printing layer 110 is formed on the dummy substrate 1
07 are not uniformly formed on the entire surface of the first smooth surface 108, and there are a portion where characters and pictures are formed as the print layer 110 and a portion where the print layer 110 is not formed. There are irregularities due to the print layer 110 on the first smooth surface 108. Further, as shown in FIG. 2, the printing layer 110 printed by the multi-layer (multi-color) is a first printing layer 201.
And the second print layer 202, and the first smooth surface 108 has unevenness due to the print layer 110. The printing layer 110 is formed by a printing method such as ordinary gravure printing, offset printing, and tampo printing. Here, the thickness per printing layer, that is, the unevenness of the printing layer 110 is typically 20 steps.
３０30 μm.

The reflective layer 104 covering the information surface 102 of the transparent substrate 101 is covered by the buffer layer 105. Buffer layer 1
Reference numeral 05 is made of a resin such as an ultraviolet curable resin or a thermosetting resin having a pencil hardness in a predetermined range described later, and is formed by a spin coating method, a drop pressing method, or the like.

The transparent substrate 101 and the dummy substrate 107 are bonded together by the adhesive layer 106 such that the buffer layer 105 and the print layer 110 are on the inside. The adhesive layer 106 is made of a resin such as an ultraviolet curable resin, and is formed on the surface of the buffer layer 105 formed on the transparent substrate 101 or on the printed layer 110 formed on the dummy substrate 107 by a spin coating method, a dropping pressure method, or the like. The transparent substrate 101 and the dummy substrate 107 are bonded together.

Next, the buffer layer 1 of the optical information recording medium of the present invention.
Experimental results for selecting a resin that can be used as 05 will be described. Information surface 10 of transparent substrate 101
Various resins were formed on the surface of the reflective layer 104 formed on the substrate 2 by spin coating and cured, and a plurality of types of single-sided disks on which the buffer layers 105 made of different resins were formed were produced. Here, a plurality of types of buffer layers 105 having a thickness of 10 to 100 μm were prepared for each resin.

Thereafter, J is applied to each buffer layer 105.
A pencil scratch test specified in IS K5400 was performed. The pencil scratch test is a method of measuring the hardness of the coating film using pencils of different hardness. (Speed: about 0.5mm
/ Sec), the hardness symbol at which the painted surface is first scratched is measured.

After measuring the pencil hardness of each buffer layer 105 made of a different kind of resin, the buffer layer 10
5 and the dummy substrate 107 on which the print layer 110 is formed on the first smooth surface 108.
The buffer layer 105 and the print layer 110 were bonded to each other via the adhesive layer 106 so as to face each other to obtain an optical information recording medium. Then, with respect to all types of the produced optical information recording media, the printed layer 11 was visually observed from the transparent substrate 101 side.
An inspection was performed to determine whether or not deformation due to 0 irregularities could be confirmed.

Table 1 shows the results of observing whether or not the deformation of the adhesive layer, the reflective layer and the transparent substrate due to the unevenness of the printing layer can be visually recognized from the transparent substrate side according to the pencil hardness of the buffer layer. Here, as described above, the thickness of the buffer layer 105 was changed in the range of 10 to 100 μm for each resin, but the thickness of the resin having any pencil hardness was 40 μm.
Deformation was observed at a film thickness of less than. Table 1 shows the results when the thickness of the print layer is 40 μm or more. In Table 1, x indicates that deformation was observed, and ○ indicates that no deformation was observed.

[0034]

[Table 1]

As shown in Table 1, when the pencil hardness of the resin used as the buffer layer 105 is in the range of HB to 6B,
No deformation due to the unevenness of the print layer 110 could be confirmed. That is, if the pencil hardness of the resin used for the buffer layer 105 is in the range of HB to 6B, the unevenness of the print layer 110 can be absorbed, and the print layer 1
It was found that no deformation due to the 10 irregularities appeared.

In the above embodiment, the reflection layer 10 shown in FIG.
The optical information recording medium having the configuration in which the buffer layer 105 is formed between the adhesive layer 10 and the adhesive layer 106 has been described.
Similar results were obtained when the buffer layer 105 was formed between the printing layer 6 and the printing layer 110. DVD shown in FIG.
Similar results were obtained with an optical information recording medium having a configuration having two layers of information surfaces on one side as in -9.

Further, in the above-described embodiment, the read-only optical information recording medium having the configuration in which the information surface 102 having the pit row 103 is covered with the reflective layer 104 has been described, but the DVD-R shown in FIG. As described above, a recording layer made of a material capable of recording and rewriting information is formed on an information surface having a guide groove, and a write-once or rewritable optical information in which a reflective layer or an interference layer is formed on the recording layer. Similar results were obtained with a recording medium.

Further, in the above-described embodiment, the structure in which the buffer layer 105 and the adhesive layer 106 are provided as separate layers has been described. However, the structure in which the adhesive layer also serves as the buffer layer is adopted.
The same result was obtained when the pencil hardness after curing was in the range of HB to 6B.

[0039]

According to the optical information recording medium of the present invention, a buffer layer for absorbing irregularities due to the print layer formed on the bonding surface side of the dummy substrate is provided between the print layer and the adhesive layer or has an information surface. Since it is provided between the information surface of the substrate and the printed layer formed on the dummy substrate, the information surface of the adhesive layer, the reflective layer and the transparent substrate are not pressed and deformed by the unevenness of the printed layer. In addition, no deformation is visually observed from the transparent substrate side, and the aesthetic appearance of the disc can be maintained.

According to the optical information recording medium of the present invention,
Since there is no deformation of the reflective layer or the information surface due to the unevenness of the printing layer, the jitter of the reproduced signal does not increase.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a cross-sectional structure of one embodiment of an optical information recording medium of the present invention.

FIG. 2 is a schematic diagram showing a case where a printing layer is printed in a multi-layer manner in one embodiment of the optical information recording medium of the present invention.

FIG. 3 is a schematic diagram showing a cross-sectional structure of a conventional DVD-5.

FIG. 4 is a schematic diagram showing a cross-sectional structure of a conventional DVD-9.

FIG. 5 is a schematic diagram showing a cross-sectional structure of a DVD-R having one recording layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Transparent substrate 102 Information surface 103 Pit row 104 Reflection surface 105 Buffer layer 106 Adhesive layer 107 Dummy substrate 108 First smooth surface 109 Second smooth surface 110 Print layer 201 First print layer 202 Second print layer 301 Transparent substrate 302 Information surface 303 Reflective layer 304 Adhesive layer 305 Dummy substrate 306 Pickup 307 Laser beam 401 Transparent substrate 402 First information surface 403 Translucent reflective layer 404 Transparent resin layer 405 Second information surface 406 Reflective layer 407 Adhesive layer 408 Dummy substrate 409 Pickup 410 Laser light 501 Transparent substrate 502 Guide groove 503 Recording layer 504 Reflective layer 505 Adhesive layer 506 Dummy substrate 507 Pickup 508 Laser light

Claims (5)

[Claims] 1. A substrate having an information surface in which information is recorded as a pit row or a guide groove is formed on one surface, a transparent dummy substrate having a first smooth surface and a second smooth surface, An optical information recording medium comprising: a printed layer and a buffer layer for absorbing irregularities caused by the printed layer are sequentially formed on the first smooth surface of the dummy substrate; An optical information recording medium, wherein a surface and the buffer layer are bonded to each other via an adhesive layer so as to face each other. 2. A substrate having an information surface in which information is recorded as a pit row or a guide groove is formed on one side, a transparent dummy substrate having a first smooth surface and a second smooth surface, and An optical information recording medium comprising: a printing layer is formed on the first smooth surface of the dummy substrate; and the printing is performed on the information surface of the substrate via a recording layer and / or a reflection layer. An optical information recording medium, wherein a buffer layer is formed to absorb irregularities caused by a layer, and the substrate and the dummy substrate are bonded together via an adhesive layer such that the buffer layer and the print layer face each other. 3. A substrate provided with an information surface on which information is recorded as a pit row or a guide groove is formed on one surface, a transparent dummy substrate provided with a first smooth surface and a second smooth surface. An optical information recording medium comprising: a printed layer formed on the first smooth surface of the dummy substrate; and the substrate and the dummy substrate are arranged so that the information surface and the printed layer face each other. An optical information recording medium, wherein the optical information recording medium is bonded via an adhesive layer that absorbs irregularities caused by the optical recording medium. 4. The optical information recording medium according to claim 1, wherein the buffer layer has a pencil hardness in the range of HB to 6B and a thickness of 40 to 100 μm. Optical information recording medium. 5. The optical information recording medium according to claim 3, wherein
An optical information recording medium, wherein the adhesive layer has a pencil hardness in the range of HB to 6B and a thickness of 40 to 100 μm.