JPH10222872A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable recording and reproducing of information with excellent characteristic having little noise, etc., caused by double refraction of a transparent substrate. SOLUTION: An optical information recording medium is provided with a substrate 101 having an information surface 102 on which information is recorded as pit rows 104 or guiding grooves for executing tracking control of light beams are formed and a first smooth surface 103 and a dummy substrate 107 having a second smooth surface 108 and a third smooth surface 109 and being transparent to the light beams. In the optical information recording medium, the substrate 101 and the dummy substrate 107 are stuck together via a transparent adhering layer 106 transparent to the light beams so that the information surface 102 and the second smooth surface 108 are facing to each other and further an incident plane of the light beams is a third smooth surface 109.

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 for reproducing information recorded on a substrate by irradiating the substrate with a laser beam, and more particularly, to an optical information recording medium comprising two substrates bonded together. It relates to a recording medium.

[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 stores 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 representing a disc title or the like is printed on the surface of the transparent substrate opposite to the laser incident side.

On the other hand, the development of DVDs (Digital Versatile Discs) whose recording density has been increased to about seven times or more that of CDs has been progressing. The DVD has been developed as a next-generation optical disc, and is a large-capacity optical disc for recording digital audio / video signals and computer data.

[0006] DVDs employ some new technologies for increasing the recording density on optical disks in order to secure a large capacity. For example, the thickness of the substrate is 0.6 mm, and the two substrates are bonded to each other to have a thickness of 1.2 mm.
mm optical disk. In this case, information can be recorded on each substrate, and single-sided two-layer reproduction can be performed. Read-only DVD-ROMs have many specifications such as DVD-5, 9, 10, and 18, depending on the recording capacity and functions. Further, a DVD-R in which a user can record information once only by himself / herself and a DVD-RAM in which information can be rewritten many times have been proposed.

[0007] As a read-only type DVD capable of reproducing information from one side, a DV having only one information side is used.
D-5 and DVD-9 capable of reproducing two information surfaces from one side. FIG. 4 is a schematic diagram showing a cross-sectional structure of the DVD-5. In the figure, 401 is a transparent substrate, 402 is an information surface, 403 is a reflective layer, 404 is an adhesive layer, 405 is a dummy substrate, 406 is a pickup, and 407 is a laser beam. DVD-5 has a diameter of 1 on which the information surface 402 is formed.
A transparent substrate 401 having a thickness of 20 mm and a thickness of 0.6 mm and a dummy substrate 405 having no information surface and a diameter of 120 mm and a thickness of 0.6 mm were bonded by an adhesive layer 404 such that the information surface 402 was on the inside. It has a configuration. Information side 4
02 is covered with a reflective layer 403 made of metal such as aluminum which reflects most of the laser light, and the recorded information is reproduced from one side through the transparent substrate 401 by the laser light 407 emitted from the pickup 406. .

FIG. 5 is a schematic diagram showing a cross-sectional structure of the DVD-9. In the drawing, reference numeral 501 denotes a first transparent substrate, 502 denotes a first information surface, 503 denotes a translucent reflective layer, 504 denotes a transparent adhesive layer, 505 denotes a second information surface, 506 denotes a reflective layer, and 507 denotes a second layer. A transparent substrate, 508 indicates a pickup, and 509 indicates a laser beam. DVD-9 has a first transparent substrate 501 having a diameter of 120 mm and a thickness of 0.6 mm on which a first information surface 502 is formed, and a diameter of 12 mm on which a second information surface 505 is formed.
A second transparent substrate 507 having a thickness of 0 mm and a thickness of 0.6 mm,
The first information surface 502 and the second information surface 505 are bonded together by a transparent adhesive layer 504 such that they face inside.

[0009] The surface of the first information surface 502 is covered with a translucent reflective layer 503 made of a dielectric material such as aluminum nitride which reflects a part of the laser beam and transmits the rest, and the surface of the second information surface 505. Is covered with a reflective layer made of a metal such as aluminum which reflects most of the laser light, and the recorded information is reproduced by the laser light 5 emitted from the pickup 508.
09, through one side through the first transparent substrate 501.

[0010] DVD-R and DVD-RAM also
It is considered that a configuration having only one information surface similar to that of DVD-5 is mainly used. FIG. 6 is a schematic diagram showing a cross-sectional structure of the DVD-R. In the figure, 601 is a transparent substrate, 602 is a guide groove, 603 is a recording layer, 604 is a reflective layer, 605 is an adhesive layer, 606 is a dummy substrate, 607 is a pickup,
Reference numeral 8 denotes a laser beam. The DVD-R includes a transparent substrate 601 on which a guide groove 602 for controlling tracking of a laser beam 608 emitted from a pickup 607 is formed, and a recording layer formed on the guide groove 602 and made of an organic dye such as a cyanine dye. 603, a reflective layer 604 formed on the recording layer 603 and made of a metal such as aluminum or gold and reflecting most of the laser light 608, and a reflective layer 604.
And the dummy substrate 606 having smooth surfaces on both sides are the adhesive layer 6
05.

Recording of information on DVD-R and DVD-R
Is reproduced through the transparent substrate 601 by the laser light 608 emitted from the pickup 607.

The currently proposed DVD specification has a track pitch of about 0.7 μm (for a DVD-R, a track pitch of about 0.7 μm).
8 μm), the shortest pit length is about 0.4 μm, the linear velocity during reproduction is constant at about 3.5 m / s, the storage capacity is about 4.7 Gbytes on one side (DVD-R is about 3.9 Gbytes on one side), and the wavelength of the reproduction laser beam Is 630 to 660 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,
In the case of DVD-5, DVD-R and DVD-RAM, the surface of the dummy substrate, in the case of DVD-9, the surface of the second transparent substrate on the side opposite to the second information surface, the disk title and the like, like the CD. The label that represents can be printed.

[0014]

The DVD has a thin substrate of 0.6 mm and a track pitch of about 0.7.
μm and the shortest pit length is about 0.4 μm (in the case of DVD-R, the track pitch is about 0.8 μm and the guide groove depth is 100 n
m or more). Therefore, when molding a transparent substrate by injection molding, in order to accurately transfer the shape of the pits and guide grooves, increase the mold temperature when molding the transparent substrate, molding pressure, molten resin to fill the mold The molding conditions must be stricter than in the conventional CD, such as by controlling the filling speed and the resin temperature in the mold with high precision.

However, if it is attempted to enhance the transferability of the pit rows or guide grooves, the birefringence of the injection-molded transparent substrate increases, resulting in a substrate having a birefringence of several hundred nm or more. In other words, the transferability of the pit row and the guide groove and the birefringence have a trade-off relationship.

If the transferability of the pit rows and guide grooves is poor,
Noise due to pit shape and guide groove shape increases,
High quality reproduced signals cannot be obtained. Also, when the birefringence is large, the noise in the reproduced signal increases, and a high-quality reproduced signal cannot be obtained.

[0017]

According to a first aspect of the present invention, there is provided an optical information recording medium comprising: a guide groove for recording information as a pit row or for performing tracking control of a light beam; An optical information recording medium comprising: a substrate having an information surface formed with a first surface and a first smooth surface; and a dummy substrate having a second smooth surface and a third smooth surface and being transparent to the light beam. The substrate and the dummy substrate are bonded together via a transparent adhesive layer that is transparent to the light beam so that the information surface and the second smooth surface face each other, and the light beam incident surface is the second surface. 3 is a smooth surface.

According to a second aspect of the present invention, there is provided an optical information recording medium comprising: an information surface on which information is recorded as a pit row;
A substrate having a second smooth surface and a third substrate having a third smooth surface, and a dummy substrate transparent to a light beam for reproducing the information, wherein the information surface has the light The substrate and the dummy substrate are covered with a reflective layer that reflects most of the beam, and have a transparent adhesive layer that is transparent to the light beam on the reflective layer. The information surface and the second smooth surface are formed on the substrate and the dummy substrate. The light beam is incident on the third smooth surface so as to face each other via the transparent adhesive layer.

According to a third aspect of the present invention, there is provided an optical information recording medium, comprising: an information surface having a guide groove for performing tracking control of a recording, erasing, or reproducing light beam;
And a dummy substrate having a second smooth surface and a third smooth surface and being transparent to the light beam, wherein the information surface reflects most of the light beam. A recording layer that is covered with a reflective layer and that optically records information on the reflective layer is formed; and a transparent adhesive layer that is transparent to the light beam is provided on the recording layer. The substrate and the dummy substrate Are bonded together via the transparent adhesive layer so that the information surface and the second smooth surface face each other, and the light beam incident surface is the third smooth surface.

According to a fourth aspect of the present invention, there is provided an optical information recording medium comprising a substrate having a first information surface on which information is recorded as a pit row and a first smooth surface, a second smooth surface and a second smooth surface. 3
A dummy substrate that is transparent to a light beam for reproducing the information, and the first information surface is covered with a reflective layer that reflects most of the light beam. A transparent resin layer transparent to the light beam is formed on the layer, and a second information surface on which information is recorded as a pit row is formed on a surface of the transparent resin layer opposite to the reflective layer, The second information surface is covered with a translucent reflective layer that transmits a part of the light beam and reflects the rest, and includes a transparent adhesive layer that is transparent to the light beam on the translucent reflective layer. The substrate and the dummy substrate are bonded via the transparent adhesive layer such that the second information surface and the second smooth surface face each other, and the light beam incident surface is the third smooth surface. It is characterized by the following.

According to a fifth aspect of the present invention, in the optical information recording medium according to the first to fourth aspects, the pit rows or the guide grooves are clockwise as viewed from the first smooth surface. It is characterized by being formed in a spiral shape.

An optical information recording medium according to the present invention is the optical information recording medium according to any one of claims 1 to 5, further comprising a printing layer having a display composed of characters and / or patterns on the first smooth surface. It is characterized by the following.

According to the optical information recording medium of the present invention, information is recorded or reproduced by inputting a light beam from the side of the dummy substrate on which the information surface is not formed. Configuration. Since it is not necessary to form a fine pattern such as a pit row or a guide groove on the dummy substrate, there is no need to consider the transferability at the time of forming the substrate, and it is easy to reduce the birefringence. Therefore, information can be recorded and reproduced with good characteristics with little noise or the like due to birefringence of the substrate.

According to the optical information recording medium of the fifth aspect of the present invention, a pit row or a data row is recorded in a spiral direction opposite to that of a conventional DVD or the like. In this case, the recording, erasing or reproducing of information can be performed by rotating the disk in the same rotation direction as that of the conventional DVD. Therefore,
It is possible to provide a compatible medium capable of performing recording, erasing, or reproducing without changing a conventional DVD recording / reproducing apparatus or the like.

According to the optical information recording medium of the present invention, printed information is provided on the surface of the substrate having the information surface, and printed information is provided on the dummy substrate side so that a light beam can be incident thereon. Therefore, information can be recorded, erased, or reproduced from the side of the dummy substrate having a small birefringence, and an optical information recording medium having a printed display like a conventional DVD can be provided. it can.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical information recording medium of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a cross-sectional structure of a first embodiment of the optical information recording medium of the present invention. In the figure, 101 is a substrate, 102 is an information surface, 103
Is a first smooth surface, 104 is a pit row, 105 is a reflective layer,
106 is a transparent adhesive layer, 107 is a dummy substrate, 108 is a second smooth surface, 109 is a third smooth surface, 110 is a pickup, and 111 is a laser beam.

The optical information recording medium of this embodiment is a conventional DVD.
It has a configuration corresponding to -5. The substrate 101 has an information surface 102 on which a pit row 104 is formed and a first smooth surface 10.
3 is provided. The information surface 102 is a pickup 110
Is covered with a reflective layer 105 made of a metal such as aluminum or gold, which reflects most of the laser light 111 emitted from the laser.

The dummy substrate 107 has a second smooth surface 108 and a third smooth surface 109 on which no pit rows or guide grooves are formed.
11 is attached via a transparent adhesive layer 106 made of a transparent ultraviolet curable resin or the like. At this time, the bonding is performed such that the information surface 102 of the substrate 101 and the second smooth surface 108 of the dummy substrate 107 face each other.

In the optical information recording medium of the present embodiment, the reproduction of the information recorded on the information surface 102 is performed by the laser beam 111 emitted from the pickup 110. This is performed from the 107 side. That is, the laser beam 111 is transmitted to the dummy substrate 1
07, the light passes through the transparent adhesive layer 106, is reflected by the reflective layer 105 formed into a shape corresponding to the shape of the pit row 104 formed on the information surface 102, and is again reflected by the transparent adhesive layer 106.
The light passes through the dummy substrate 107 and returns to the pickup 110, where the information is reproduced.

As described above, in the optical information recording medium of this embodiment, the reproduction of information is not performed from the side of the substrate 101 where the birefringence is increased as a result of enhancing the transferability of the pit array 104, and the pit array is not used. Is performed from the side of the dummy substrate 107 which does not have any noise, so that information can be reproduced with good characteristics with little noise or the like due to birefringence of the substrate.

In the optical information recording medium of this embodiment, the spiral direction of the pit row 104 is
When viewed from the third smooth surface 109 side of the dummy substrate 107, the spiral direction of the pit row 104 is counterclockwise when viewed from the third smooth surface 109 of the dummy substrate 107. That is, when the laser beam 111 is incident from the dummy substrate 107 side, information can be reproduced in the same rotation direction as that of the conventional DVD, so that the light of the present embodiment can be reproduced without any modification to the conventional DVD reproducing apparatus. The information recording medium can be reproduced.

Further, in the optical information recording medium of the present embodiment, it is possible to print and display characters and patterns on the first smooth surface 103 of the substrate 101. In this case, since it cannot be apparently distinguished from the conventional DVD-5, the user is not worried that the disc is a special disc.

FIG. 2 is a schematic view showing a sectional structure of a second embodiment of the optical information recording medium of the present invention. In the figure, 201 is a substrate, 202 is an information surface, 203 is a first smooth surface, 204
Is a guide groove, 205 is a reflective layer, 206 is a recording layer, 207 is a transparent adhesive layer, 208 is a dummy substrate, 209 is a second smooth surface, 210 is a third smooth surface, 211 is a pickup,
Reference numeral 12 denotes a laser beam.

The optical information recording medium of this embodiment is a conventional DVD.
It has a configuration corresponding to -R. The substrate 201 has an information surface 202 on which a guide groove 204 is formed and a first smooth surface 203.
Is provided. The information surface 202 is covered with a reflective layer 205 made of a metal such as aluminum or gold that reflects most of the laser light 212 emitted from the pickup 211. On the reflection layer 205, a recording layer 206 made of an organic dye such as a cyanine dye is formed.

The dummy substrate 208 has a second smooth surface 209 and a third smooth surface 210 on which no pit rows or guide grooves are formed.
12 is bonded via a transparent adhesive layer 207 made of a transparent ultraviolet curable resin or the like. At this time, the information surface 202 of the substrate 201 and the second smooth surface 209 of the dummy substrate 208 are bonded so that they face each other. At the time of bonding, the recording layer 206 is
A transparent protective layer (not shown) made of a dielectric or the like may be provided between the recording layer 206 and the transparent adhesive layer so as not to dissolve in the recording layer 7.

In the optical information recording medium of this embodiment, recording of information on the information surface 202 is performed by a laser beam 212 emitted from the pickup 211 and modulated based on a recording signal. Differently, the process is performed from the dummy substrate 208 side. That is, the laser light 212
Indicates that the recording layer 206 formed on the reflective layer 205 formed in a shape corresponding to the shape on the guide groove 204 formed in the information surface 202 through the dummy substrate 208 and the transparent adhesive layer 207 is recorded information. The information is recorded by optically changing according to.

In the optical information recording medium of this embodiment, the information recorded on the information surface 202 as described above is reproduced by the laser light 212 emitted from the pickup 211.
This is performed from the dummy substrate 208 side unlike the conventional DVD-R. That is, the laser light 212
Is the amount of light that passes through the dummy substrate 208 and the transparent adhesive layer 207 and is reflected by the reflective layer 205 formed in a shape corresponding to the shape of the guide groove 204 formed in the information surface 202 in accordance with the optical change of the recording layer 206. And again, the transparent adhesive layer 2
07, the pickup 211 transmitted through the dummy substrate 208
And the information is reproduced.

As described above, in the optical information recording medium of the present embodiment, as a result of enhancing the transferability of the guide groove 204, information is not recorded and reproduced from the substrate 201 side where the birefringence is increased. Dummy substrate 208 having no guide groove at all
Since recording is performed from the side, information can be recorded / reproduced with good characteristics with little noise or the like due to birefringence of the substrate.

In the optical information recording medium of this embodiment, if the spiral direction of the guide groove 204 is formed clockwise as viewed from the first smooth surface 203 of the substrate 201, the dummy substrate 208 When viewed from the third smooth surface 210 side, the spiral direction of the guide groove 204 is counterclockwise. That is, when the laser beam 212 is incident from the dummy substrate 208 side, information can be recorded / reproduced in the same rotation direction as the conventional DVD, so that the present embodiment can be performed without any modification to the conventional DVD reproducing apparatus. Recording and reproduction of the optical information recording medium of the example can be performed.

Further, in the optical information recording medium of the present embodiment, it is also possible to print and display characters and patterns on the first smooth surface 203 of the substrate 201. In this case, since it cannot be apparently distinguished from the conventional DVD-R, the user is not worried that the disc is a special disc.

As another mode of this embodiment, the recording layer 206
Instead of an organic dye material, a phase change recording material such as a GeTeSb material or a magneto-optical recording material such as a TbFeCo material can be used. In this case, the recording layer 2
06 may be sandwiched between dielectric layers.

FIG. 3 is a schematic view showing a sectional structure of a third embodiment of the optical information recording medium of the present invention. In the figure, 301 is a substrate, 302 is a first information surface, 303 is a first smooth surface,
304 is a reflective layer, 305 is a transparent resin layer, 306 is a second information surface, 307 is a translucent reflective layer, 308 is a transparent adhesive layer,
309 is a pit row, 310 is a dummy substrate, 311 is a second
Reference numeral 312 denotes a third smooth surface, 313 denotes a pickup, and 314 denotes a laser beam.

The optical information recording medium of this embodiment is a conventional DVD.
-9. The substrate 301 has a first information surface 302 on which a pit row 309 is formed and a first smooth surface 303. The information surface 302 is covered with a reflective layer 304 made of a metal such as aluminum or gold that reflects most of the laser light 314 emitted from the pickup 313.

On the reflection layer 304, a transparent resin layer 305 made of an ultraviolet curable resin transparent to the laser beam 314 is laminated, and a pit row is formed on the surface of the transparent resin layer 305 opposite to the reflection layer 304. The second information surface 306 on which the 309 is formed is formed. The second information surface 306 is covered with a translucent reflective layer 307 made of a metal, a dielectric, or the like that reflects a part of the laser beam 314 and transmits the rest.

The dummy substrate 310 has a second smooth surface 311 and a third smooth surface 312 on which no pit rows or guide grooves are formed.
14 are bonded via a transparent adhesive layer 308 made of a transparent ultraviolet curable resin or the like. At this time, the first information surface 302 of the substrate 301 and the second
Are bonded so that the smooth surfaces 311 face each other.

In the optical information recording medium of this embodiment, the first
The information recorded on the information surface 302 is reproduced by the laser light 314 emitted from the pickup 313, but is reproduced from the side of the dummy substrate 310 having no information surface unlike the conventional DVD-9. That is, the laser beam 314 passes through the dummy substrate 310, the transparent adhesive layer 308, the translucent reflective layer 307, and the transparent resin layer 305, and has a shape corresponding to the shape of the pit row 309 formed on the first information surface 302. The pit row 309 is formed by the formed reflective layer 304.
, And again, the transparent resin layer 305, the translucent reflective layer 307, the transparent adhesive layer 308, and the dummy substrate 31
The signal passes through 0 and returns to the pickup 313 to reproduce information.

When information recorded on the second information surface 306 is reproduced, the focal position of the laser beam 314 emitted from the pickup 313 is set to the second information surface 306.
Dummy substrate 31 which switches to the upper side and also has no information surface
It is performed from the 0 side. That is, the laser light 314 passes through the dummy substrate 310 and the transparent adhesive layer 308, and is formed by the translucent reflective layer 307 formed in a shape corresponding to the shape of the pit row 309 formed on the second information surface 306. Row 30
9 and is reflected again by the amount of light corresponding to
The light passes through the dummy substrate 310 and returns to the pickup 313, where the information is reproduced.

As described above, in the optical information recording medium of the present embodiment, the reproduction of information is not performed from the side of the substrate 301 where the birefringence becomes large as a result of enhancing the transferability of the pit row 309, and Since the process is performed from the side of the dummy substrate 310 having no row, information can be reproduced with good characteristics with little noise or the like due to birefringence of the substrate.

In the optical information recording medium of this embodiment, the direction of the spiral of the pit row 309 is
When viewed from the third smooth surface 312 side of the dummy substrate 310, the spiral direction of the pit row 309 is counterclockwise when viewed from the third smooth surface 312 side of the dummy substrate 310. That is, when the laser beam 314 is incident from the dummy substrate 310 side, information can be reproduced in the same rotation direction as that of the conventional DVD, so that the light of the present embodiment can be reproduced without any modification to the conventional DVD reproducing apparatus. The information recording medium can be reproduced.

Further, in the optical information recording medium of the present embodiment, it is possible to print and display characters and patterns on the first smooth surface 303 of the substrate 301. In this case, since it cannot be apparently distinguished from the conventional DVD-9, the user is not worried that the disc is a special disc.

Regarding the characteristics of the optical information recording medium of the present invention,
Hereinafter, a specific example will be described. As a representative example, an optical information recording medium having the same structure as that of the first embodiment shown in FIG. 1 will be described.

[0052]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A diameter 1 having a spiral pit row 104 having a shortest pit length of 0.4 μm and a track pitch of 0.74 μm.
A substrate 101 having a thickness of 20 mm and a thickness of 0.6 mm was formed by injection molding a polycarbonate resin. The molding conditions were such that the transferability of the pit row 104 was the best.
At this time, the vertical birefringence varied greatly from 10 to 90 nm. Information surface 1 with pit row 104 formed
A reflective layer 105 made of aluminum was formed by a sputtering method so as to cover No. 02.

Next, a diameter of 120 m without a pit row
A dummy substrate 107 having a thickness of 0.6 mm and a thickness of 0.6 mm was formed by injection molding a polycarbonate resin. The molding conditions were such that the birefringence was minimized. The birefringence in the vertical direction at this time was very small, 8 to 12 nm, and the variation was small. An ultraviolet curable resin is applied on the reflective layer 105 of the substrate 101 to form a transparent adhesive layer 106 on the dummy substrate 1.
07 and irradiating with ultraviolet light to form the transparent adhesive layer 106.
Was cured to obtain an optical information recording medium.

The optical information recording medium obtained as described above is used as a pickup 110 having a reproduction laser beam wavelength of 650 nm.
And the reproduced signal characteristics were evaluated. Here, the reproducing apparatus can change the rotating direction of the disk.

First, the laser beam 111 is applied to the first
When the reproduced signal characteristic was measured, the eye pattern appeared to fluctuate up and down, and the clock jitter was 14.2%.

Next, when the rotation direction of the disk was changed and the laser beam 111 was made incident from the third smooth surface 109 side of the dummy substrate 107 and the reproduction signal characteristics were measured, the eye pattern appeared to be open and stationary. And the clock jitter was 7.3%.

The same measurement was performed on an optical information recording medium having the same configuration as the second and third embodiments, and similar results were obtained.

[0058]

According to the optical information recording medium of the present invention, recording or reproduction of information can be performed by irradiating a light beam from a dummy substrate side on which an information surface is not formed. Since it is not necessary to form a fine pattern such as a pit row or a guide groove on the dummy substrate, there is no need to consider the transferability at the time of forming the substrate, and it is easy to reduce birefringence. Therefore, recording of information, with good characteristics with less noise due to the birefringence of the substrate,
Playback can be performed.

According to the optical information recording medium of the present invention, since a pit row or a data row is recorded in a spiral direction opposite to that of a conventional DVD or the like, a light beam for recording or reproduction is incident from the dummy substrate side. In this case, information can be recorded, erased, or reproduced by rotating the disk in the same rotation direction as the conventional DVD. Therefore, it is possible to provide a completely compatible medium capable of performing recording, erasing, or reproducing without changing a conventional DVD recording / reproducing apparatus or the like.

According to the optical information recording medium of the present invention, the printed display is provided on the surface of the substrate having the information surface, and the printed display is not provided on the dummy substrate side so that the light beam can enter. It is possible to provide an optical information recording medium on which information can be recorded, erased or reproduced from the side of the dummy substrate having a small birefringence, and which has a printed display in appearance, similarly to a conventional DVD.

[0061]

[Brief description of the drawings]

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

FIG. 2 is a schematic diagram showing a cross-sectional structure of a second embodiment of the optical information recording medium of the present invention.

FIG. 3 is a schematic diagram showing a cross-sectional structure of a third embodiment of the optical information recording medium of the present invention.

FIG. 4 is a schematic diagram showing a cross-sectional structure of DVD-5.

FIG. 5 is a schematic diagram showing a cross-sectional structure of DVD-9.

FIG. 6 is a schematic diagram showing a cross-sectional structure of a DVD-R.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Substrate 102 Information surface 103 First smooth surface 104 Pit row 105 Reflective layer 106 Transparent adhesive layer 107 Dummy substrate 108 Second smooth surface 109 Third smooth surface 110 Pickup 111 Laser beam 201 Substrate 202 Information surface 203 First Smooth surface 204 Guide groove 205 Reflective layer 206 Recording layer 207 Transparent adhesive layer 208 Dummy substrate 209 Second smooth surface 210 Third smooth surface 211 Pickup 212 Laser beam 301 Substrate 302 First information surface 303 First smooth surface 304 Reflective layer 305 Transparent resin layer 306 Second information surface 307 Translucent reflective layer 308 Transparent adhesive layer 309 Pit row 310 Dummy substrate 311 Second smooth surface 312 Third smooth surface 313 Pickup 314 Laser beam 401 Transparent substrate 402 Information surface 403 Reflective layer 404 G row 405 Dummy substrate 406 Pickup 407 Laser light 501 Transparent substrate 502 First information surface 503 Translucent reflective layer 504 Transparent resin layer 505 Second information surface 506 Reflective layer 507 Second transparent substrate 508 Pickup 509 Laser light 601 Transparent Substrate 602 Guide groove 603 Recording layer 604 Reflective layer 605 Adhesive layer 606 Dummy substrate 607 Pickup 608 Laser beam

Claims (6)

[Claims] 1. A substrate having an information surface on which information is recorded as a pit row or a guide groove for performing tracking control of a light beam and a first smooth surface, a second smooth surface and a second smooth surface. 3. An optical information recording medium comprising: a dummy substrate having a third smooth surface and being transparent to the light beam; wherein the substrate and the dummy substrate are arranged such that the information surface and the second smooth surface face each other. An optical information recording medium, wherein the optical information recording medium is bonded to a light beam via a transparent adhesive layer, and the light beam incident surface is the third smooth surface. 2. A substrate having an information surface on which information is recorded as a pit row and a first smooth surface, and a light for reproducing the information having a second smooth surface and a third smooth surface. A dummy substrate that is transparent to the beam, the information surface is covered with a reflective layer that reflects most of the light beam, and a transparent adhesive layer that is transparent to the light beam is provided on the reflective layer. The substrate and the dummy substrate are bonded together via the transparent adhesive layer such that the information surface and the second smooth surface face each other, and the light beam incident surface is the third smooth surface. Characteristic optical information recording medium. 3. A substrate having an information surface formed with a guide groove for performing tracking control of a recording, erasing or reproducing light beam and a first smooth surface, a second smooth surface and a third smooth surface. A dummy substrate having a smooth surface and being transparent to the light beam, wherein the information surface is covered with a reflective layer that reflects most of the light beam, and optically records information on the reflective layer. A recording layer is formed, and a transparent adhesive layer that is transparent to the light beam is provided on the recording layer. The substrate and the dummy substrate are transparent so that the information surface and the second smooth surface face each other. An optical information recording medium which is bonded via an adhesive layer, wherein the light beam incident surface is the third smooth surface. 4. A method according to claim 1, wherein information is recorded as a pit string.
A substrate having an information surface and a first smooth surface, and a dummy substrate having a second smooth surface and a third smooth surface and being transparent to a light beam for reproducing the information, The first information surface is covered with a reflective layer that reflects most of the light beam, a transparent resin layer transparent to the light beam is formed on the reflective layer, and the transparent resin layer is opposite to the reflective layer. A second information surface on which information is recorded as a pit row is formed on the side surface, and the second information surface is covered with a translucent reflective layer that transmits part of the light beam and reflects the rest. A transparent adhesive layer that is transparent to the light beam on the translucent reflective layer, wherein the substrate and the dummy substrate are bonded together so that the second information surface and the second smooth surface face each other. The light beam incident surface is the third smooth surface The optical information recording medium characterized Rukoto. 5. The optical information recording medium according to claim 1, wherein said pit row or guide groove is formed in a clockwise spiral as viewed from a first smooth surface. Optical information recording medium. 6. An optical information recording medium according to claim 1, further comprising a printing layer having a display made of characters and / or patterns on said first smooth surface. recoding media.