JP3444480B2 - optical disk - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc having a light-shielding identification signal which can be used for copyright protection such as prevention of illegal software use and illegal duplication prevention.

[0002]

2. Description of the Related Art Optical discs have the advantage that they can be easily distributed as packaged media at low cost because a large number of duplicated discs can be easily manufactured from a single stamper. However, in recent years, so-called pirated products have become widespread because optical disk manufacturing devices have become relatively easy to obtain. Moreover, there is no end to unauthorized use and unauthorized copying of optical disc software. As one of the measures for preventing such fraud, there is a method of preventing the manufacture and distribution of pirated discs by putting an ID number on the master disc of the optical disc and not reproducing an optical disc without this ID number. However, this method cannot completely prevent illegal duplication.

Under such circumstances, there is a method using a BCA (Burst Cutting Area) signal of a DVD (digital video disc) as an effective countermeasure for the above-mentioned fraud prevention. When the above-mentioned DVD is a read-only DVD, this read-only DVD is formed by sequentially stacking a reflective layer and a protective layer on a light transmissive substrate. Further, a lead-in area, a data area in which soft information is recorded in advance, and a lead-out area are sequentially formed from the inner circumference to the outer circumference of the disc on the light transmissive substrate. In the method described above, a physical mark (BCA signal) in which the reflective layer is partially removed by the laser trimming method is provided in the pre-pit area of the reflective layer stacked on the lead-in area. As a result, only when the BCA signal can be detected, the genuine read-only DVD is obtained. The physical mark is not directly formed on the lead-in area described above, but is directly formed on the reflective layer laminated on the lead-in area. Therefore, even if the light transmissive substrate is illegally copied, the physical mark cannot be copied. Therefore, such fraud prevention measures using physical marks are effective, and according to this method, an readable identification mark can be recorded accurately for each read-only DVD disc. (JP-A-10-233019).

[0004]

By the way, the BCA signal, which is a physical mark as described above, is formed on the reflective layer of the disk as described above. Therefore, during the optical disc master process for manufacturing the above-mentioned light-transmitting substrate, or during the laminating process for sequentially laminating the reflective layer and the protective layer on the light-transmitting substrate master manufactured by injection molding, , BCA signals cannot be formed on the reflective layer. Therefore, as a post-step of the above-mentioned lamination step, a new step of irradiating a laser beam on the reflective layer of the completed read-only DVD with a laser trimming method to provide a BCA signal is required. As a result, because of this new process, BCA
A laser trimming device dedicated to signal recording was required.
Further, when the BCA signal is applied to a single plate disc, the BCA signal can be erased by removing the protective layer and reforming the reflective layer. On the other hand, it is optically difficult to form an identification signal based on a reflectance change corresponding to the BCA signal at the master level. Therefore, the present invention has been made by paying attention to the above points, and it is provided with a data area in which main data is recorded and an inner peripheral side of the data area, and a reproduction operation of the main data. An optical disc in which a reflective layer, an adhesive layer, and a bonding substrate are sequentially laminated on a light-transmissive substrate having a specific area in which sub-data used in the case are recorded,
By providing an identification pattern light shielding layer between the reflective layer and a part of the specific region provided on the light transmissive substrate, the identification pattern light shielding layer is provided unless the reflective layer is completely removed. Since the BCA signal does not appear, this BCA
Since it is not possible to duplicate even the signal, illegal duplication,
It is an object of the present invention to provide an optical disc capable of reliably preventing illegal use of software.

[0005]

In order to solve the above-mentioned problems, the present invention provides the following optical disks (1) to (5). (1) It has a data area in which main data is recorded, and a specific area which is provided on the inner circumference side of this data area and in which sub-data used in the reproduction operation of the main data is recorded. An optical disc comprising a light-transmissive substrate, a reflective layer, an adhesive layer, and a bonding substrate sequentially laminated on the substrate,
A part of the specific area provided on the light-transmissive substrate is provided with a light-shielding object having a different identification pattern for each disc.
An optical disk, characterized in that an identification pattern light-shielding layer formed of high quality is provided between the reflection layer and the reflection layer. (2) It has a data area in which main data is recorded and a specific area which is provided on the inner circumference side of this data area and in which sub-data used in the reproduction operation of the main data is recorded. a light transmissive substrate, a reflective layer, a sequentially stacked comprising an optical disk protective layer, on a part of the specific area provided on the light transmitting substrate, a disk
Different identification patterns are formed on each sheet of light-shielding material.
An optical disc, characterized in that the identification pattern light-shielding layer is provided between the reflection layer and the identification layer. (3) It has a data area in which main data is recorded and a specific area which is provided on the inner peripheral side of this data area and in which sub-data used in the reproduction operation of the main data is recorded. An optical disc comprising a light-transmissive substrate, a reflective layer, an adhesive layer, and a bonding substrate sequentially laminated on the substrate,
Different identification for each disc on a part of the reflective layer corresponding to the specific region provided on the light transmissive substrate.
An optical disc, wherein an identification pattern light-shielding layer having a pattern formed of a light-shielding substance is provided between the adhesive layer. (4) It has a data area in which the main data is recorded and a specific area which is provided on the inner circumference side of this data area and in which sub-data used in the reproduction operation of the main data is recorded. An optical disc in which a reflective layer and a protective layer are sequentially laminated on a light transmissive substrate, wherein a disc layer is formed on a part of the reflective layer corresponding to the specific area provided on the light transmissive substrate. Shields different identification patterns for each sheet
An optical disc, wherein an adhesive layer light-shielding layer is provided between the identification pattern light-shielding layer formed of a light-transmitting substance and the protective layer. (5) The optical disc according to any one of claims 1 to 4, wherein the identification pattern light-shielding layer is a light-shielding layer made of a barcode pattern.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the optical disc of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an embodiment diagram showing the configuration of the optical disc of the present invention. FIG. 1 (A) is a top view of the optical disc of the present invention, and FIGS. 1 (B) and 1 (C) are the first and second optical discs of the present invention, respectively. FIG. 9 is a partially enlarged cross-sectional view in the radial direction of an optical disc according to a third embodiment.

The optical disc of the present invention has BCA defined by the DVD standard as an identification pattern light-shielding layer. That is, the optical disc 10 of the present invention has a central hole 10a, a lead-in area 10b, a data area 10c, and a lead-out area 10d, as shown in FIG.
Although not shown here, the lead-out area 10
Further, there is a disk peripheral portion on the outer peripheral portion of d. The BCA described above is formed as a BCA 10e in a part of a specific range (a portion indicated by a solid line in the drawing) of the lead-in area 10b. Although the BCA 10e occupies about 2/3 of the annular lead-in area 10b in the figure, the lead-in area 10b extends to the inner and outer circumference sides of the BCA 10e. Since it has a lead-in radius area (not shown), even if the BCA 10e occupies a part of the lead-in area 10b as described above, a lead-in signal from the lead-in area 10b is generated. Can be read reliably.

The optical disk 10 according to the first embodiment of the present invention.
As shown in FIG. 1B, the lead-in area 10b of A has a reflective layer 10A2, an adhesive layer 10A3, a bonded light transmissive substrate 10A4, and a printed layer 1 on a light transmissive substrate 10A1.
0A5 is sequentially laminated. The BCA 10e, which is the above-described identification pattern light-shielding layer, is directly formed (printed) on the light-transmissive substrate 10A1 as a portion 10A6 (black coating in the drawing). As a result, the portion 10A6 becomes the light-transmissive substrate 10A.
1 and the reflective layer 10A2. In the figure, the reproduction laser beam L1 is transmitted through the light-transmissive substrate 10.
It is incident from the lower side of A1. The optical disk of the second embodiment of the present invention is not shown here, but the adhesive layer 10A constituting the optical disk 10A of the first embodiment described above is used.
3 and the bonded light-transmissive substrate 10A4, a protective layer made of, for example, an ultraviolet curable resin is used, and the other configurations are the same as those of the optical disc 10A described above.

Further, as shown in FIG. 1C, the lead-in area 10b of the optical disk 10B according to the third embodiment of the present invention has a reflective layer 10B on a light-transmissive substrate 10B1.
2. The protective layer 10B3 is sequentially laminated. Then, the print layer 10B4 is formed on the lower side of the light transmissive substrate 10B1. The BCA 10e which is the above-mentioned identification pattern light-shielding layer is the reflection layer 10B formed on the light-transmissive substrate 10A1.
A portion 10B5 (black coating in the drawing) is directly formed (printed) on the second portion. As a result, the portion 10B5 is provided between the light transmissive substrate 10A1 and the reflective layer 10B2. In the figure, the reproducing laser beam L2 is incident from above the protective layer 10B3 made of, for example, an ultraviolet curable resin. Further, although not shown here, the optical disc of the fourth embodiment of the present invention has an adhesive layer and a bonded light transmitting substrate instead of the protective layer 10B3 constituting the optical disc 10B of the third embodiment. The other structure is the same as that of the optical disk 10B described above. In other words, the portion 10B5 is the light transmissive substrate 10A1.
And the adhesive layer (that is, the reflective layer 10B2).
The portion 10B5 is directly formed (printed) on the upper portion, and the portion 10B5 is provided between the bonded light-transmissive substrate and the adhesive layer (that is, on the bonded light-transmissive substrate). The portion 10B5 is directly formed (printed))
It will be.

The specific structure of the above-mentioned optical disc of the present invention is as follows (1) to (4). (1) Optical disc 10A according to the first embodiment of the present invention
As shown in FIGS. 1 (A) and 1 (B), main data (information signal) is recorded as a pre-pit signal (recorded in a concentric or spiral pattern as a pit row having minute irregularities). The data area 10c and this data area 10
Sub-data (lead-in signal) provided on the inner peripheral side (around the central hole 10a) of c and used during the reproduction operation of the main data (information signal) is recorded as a pre-pit signal (minute). On a light-transmissive substrate 10A1 having a specific area (lead-in area) 10b which is recorded as concavo-convex pits in a concavo-convex pattern or a spiral pattern. It is an optical disc in which substrates 10A4 are sequentially laminated, and light is shielded in a part (for example, a part of a lead-in radius region) on the specific region (lead-in region) 10b provided on the light transmissive substrate 10A1. The optical disc is characterized by being provided with a layer (BCA) 10e (portion 10A6). (2) The optical disc according to the second embodiment of the present invention is shown in FIG.
As shown in (A), a main data (information signal) is recorded as a pre-pit signal (concentrically or spirally recorded as a pit row having minute irregularities), and a data area 10c. Sub-data (lead-in signal) which is provided on the inner peripheral side of 10c (around the central hole 10a) and is used during the reproduction operation of the main data (information signal) is recorded as a pre-pit signal (minute). Specific area (lead-in area) 10 recorded in a concentric or spiral manner as a pit array having various irregularities
An optical disc in which a reflective layer (the same as the reflective layer 10A2) and a protective layer (not shown) are sequentially laminated on a transparent substrate (the same as the transparent substrate 10A1) having b.
A light-shielding layer (BCA) 10e (portion 10A6) is provided on a part (for example, part of the lead-in radius area) on the specific area (lead-in area) 10b provided on the light transmissive substrate.
The optical disc is characterized by being provided with.

(3) As shown in FIGS. 1A and 1C, the optical disc 10B according to the third embodiment of the present invention has main data (information signal) recorded as a prepit signal (a minute amount). A data area 10c, which is recorded as concavo-convex pits in a concavo-convex pattern or a spiral shape, and an inner peripheral side (around the central hole 10a) of the data area 10c, and the main data (information signal). A specific area (lead-in area) in which sub-data (lead-in signal) used during the reproducing operation is recorded as a pre-pit signal (recorded in concentric circles or spirals as a row of pits with minute irregularities). Light-transmissive substrate 1 having 10b
0B1 is an optical disc in which a reflective layer 10B2 and a protective layer 10B3 are sequentially laminated on the optical transparent substrate 10B.
The specific area (lead-in area) 1 provided on B1
The optical disc is characterized in that a light shielding layer (BCA) 10e (portion 10B5) is provided on a part of the reflective layer 10B2 corresponding to 0b. (4) The optical disk according to the fourth embodiment of the present invention is shown in FIG.
As shown in (A), a main data (information signal) is recorded as a pre-pit signal (concentrically or spirally recorded as a pit row having minute irregularities), and a data area 10c. Sub-data (lead-in signal) which is provided on the inner peripheral side of 10c (around the central hole 10a) and is used during the reproduction operation of the main data (information signal) is recorded as a pre-pit signal (minute). Specific area (lead-in area) 10 recorded in a concentric or spiral manner as a pit array having various irregularities
b, on a light-transmissive substrate (the same as the light-transmissive substrate 10B1), a reflective layer (the same as the reflective layer 10B2), an adhesive layer,
An optical disc having laminated light-transmissive substrates sequentially laminated, wherein a light-shielding layer is provided on a part of the reflective layer corresponding to the specific region (lead-in region) 10b provided on the light-transmissive substrate. The optical disc is characterized by being provided with (BCA) 10e (portion 10B5). Furthermore, the light shielding layer (BCA) 10e is a bar code pattern.

FIG. 2 shows an optical disc 10 according to the present invention with a BCA1.
3 is a waveform diagram including a recording signal for forming 0e and a reproduction signal reproduced from the BCA 10e. FIG. 2A is a diagram showing the position of the BCA 10e formed on the upper surface of the optical disc 10. FIG. 2B is a diagram showing a barcode signal embodying the BCA 10e. FIG. 2C shows BCA1.
It is a figure which shows the recording signal for recording as 0e. FIG. 2D is a diagram showing recording signal data. Figure 2 (E)
FIG. 6 is a diagram showing a reproduction signal reproduced from the BCA 10e. FIG. 2F is a diagram showing the envelope of the above-mentioned reproduced signal. FIG. 2G is a diagram showing reproduction signal data. As described above, the BCA 10e has a radial bar code signal (FIG. 2B) formed by removing a part of the reflective layers 10A2 and 10B2 of the optical discs 10A and 10B using a high-power laser. Is.

The recording signal for forming the BCA 10e is not limited to the radial bar code signal as described above, and another method may be used as long as the signal reproduced from the BCA 10e satisfies the range defined by the BCA standard. However, it is difficult to obtain a sufficient BCA signal by pit size, pit depth modulation, etc. in the optical disc master. This range is shown in FIG. In FIG. 3, I _14H and I _14L indicate the upper level and the lower level of the envelope of the main data reproduction signal, respectively. That is, the sections 1b and 1d in which the main data reproduction signal is present fall within the range of the levels I _14H and I _14L . On the other hand, the section 1 in which the main data reproduction signal for obtaining the reproduction signal from the BCA 10e is missing
a, 1c, and 1e are level I _14L or less. This section 1
The reflectance I _{s at} a, 1c, and 1e is below I _14L (I _s ≦ I _14L ) below the envelope of the main data reproduction signal,
And it must be below the upper 20% of the envelope (I _s / I _{14H ≤0.2} ). According to the present invention, the BCA signal is recorded during the process of stacking the optical discs 10A and 10B so as to satisfy this standard.

FIG. 4 is a process chart for explaining a method of manufacturing the optical disk 10A according to the first embodiment of the present invention. (1) First, a prepit-shaped main signal cut on a master is duplicated on a transparent substrate to obtain a light-transmissive substrate 10A1.
Are produced (FIG. 4 (A)). (2) Next, a BCA signal is printed on the pre-pit surface of the inner circumference of the substrate 10A1 (over a specific range of the lead-in area 10b) in the form of a bar code which is a light-shielding identification signal to provide the BCA portion 10A6 (FIG. 4 (B)). This printing may be performed by an inkjet printing method by rotating the substrate 10A1 at a constant number of rotations, or may be performed simply by a rubber stamp or by offset printing by overlaying a mask prepared in advance on the substrate 10A1. You may go in. When it is desired to change the disc identification signal frequently for each optical disc or in a form corresponding thereto, it is preferable to connect the identification signal generating device to the ink jet system.
When it is desired to change the identification signal for each master, the method of printing by overlapping the mask on the substrate is simple. The ink used has a high light-shielding property at the reproduction wavelength. After this, the printed ink is thoroughly dried. (3) Next, the reflective layer 10A2 is formed on the substrate 10A1 provided with the BCA portion 10A6 in the same manner as in the ordinary bonded disc manufacturing method (FIG. 4C). (4) Next, the bonded substrate 10A4 is bonded onto the reflective layer 10A2 via the adhesive layer 10A3 to form the adhesive layer 1
The ultraviolet curable resin that constitutes 0A3 is cured by irradiation with ultraviolet rays (FIG. 4 (D)). (5) Next, on the side opposite to the reading surface, which is the lower side of the light transmissive substrate 10A1 on which the reproduction laser beam L1 is incident,
Label printing is performed on the bonded substrate stack 10A4 (see FIG. 4).
(E)). Thus, the optical disk 10 of the present invention described above
A can be produced. By doing so, the portion where the identification signal is printed is in a state in which the reflection layer is shielded when viewed from the reading surface side, so that the effect of lowering the reflectance sufficiently satisfying the BCA standard can be obtained.

Further, a BCA signal recording device by a special and expensive laser trimming method is not required, and a normal bar code printing machine is applied or an offset printing machine is applied. Since it is possible to use the printing machine of, the identification signal can be generated very inexpensively.

In the first embodiment described above, a bonded disc such as a DVD has been described, but this is an optical disc which is the second embodiment of the present invention described above, for example, C.
It can also be applied to a single disk such as D. When the BCA signal recording method by laser trimming is applied to a single-plate optical disk, there is a drawback that the BCA signal can be erased by removing the protective layer to expose the reflective layer and then re-forming the reflective layer. In this method, even if the protective layer is removed, since the identification signal is formed between the reflective layer and the transparent substrate, it is necessary to completely remove the reflective layer, and it is extremely difficult to remove and re-form the identification signal. Is.

As a method of manufacturing an optical disk according to the third embodiment of the present invention, a case where main data reading by an optical head is performed from a pre-pit molding surface of a disk substrate will be described. That is, a case where data reproduction is performed from the reflective layer side, that is, the protective layer side will be described. In this case, unlike the optical disk 10A which is the first embodiment of the present invention described above,
In order to shield the reflective layer from the optical head, a light-shielding identification signal is printed on the reflective layer after the reflective layer is formed. This state is shown in FIG.

FIG. 5 is a process chart for explaining a method of manufacturing the optical disc 10B according to the third embodiment of the present invention. (1) First, a prepit-shaped main signal cut on a master is duplicated on a transparent substrate to obtain a light-transmissive substrate 10B1.
Is produced (FIG. 5A). (2) Next, the reflective layer 10B2 is formed on the substrate 10B1 (FIG. 5B). (3) Next, the BCA signal is printed on the pre-pit surface of the inner periphery of the substrate 10B1 on which the reflective layer 10B2 is formed (over a specific range of the lead-in area 10b) in the form of a bar code which is a light-shielding identification signal. A BCA portion 10B5 is provided (FIG. 5C). This printing may be performed by an inkjet printing method by rotating the substrate 10B1 at a constant number of rotations, or may be performed simply by a rubber stamp or by offset printing by overlaying a mask prepared in advance on the substrate 10B1. You may go in. When it is desired to change the disc identification signal frequently for each disc or in a form corresponding thereto, it is preferable to combine the discriminating signal generation device with the ink jet system. When it is desired to change the identification signal for each master, the method of printing by overlapping the mask on the substrate is simple. The ink used has a high light-shielding property at the reproduction wavelength. After this, the printed ink is thoroughly dried. (4) Next, the reflective layer 10A2 and the BCA portion 10B5
A protective layer 10B3 is formed thereover (FIG. 5D). (5) Next, the substrate 10 on the side opposite to the readout surface, which is the upper side of the protective layer 10B3 on which the reproduction laser beam L2 is incident.
Label printing is performed on B1 to form a printing layer 10B4 (FIG. 5 (E)). In this way, the optical disk 10B of the present invention described above can be manufactured.

The optical disk 10 produced in this way
In B, data is reproduced from the protective layer 10B3 side by the optical head, and the pit surface (reflection layer 10
Since the distance to the surface (B2 surface) is short, there is an advantage that optical aberrations are less likely to occur. If the process shown in FIG. 5 described above is performed, the present invention can be applied even in this case.

Further, in order to obtain an optical effect similar to that of the embodiment shown in FIG. 5, instead of the protective layer 10B3, a thin bonded substrate is bonded via an adhesive, and the surface on the read surface side is bonded. There is also a method for obtaining smoothness and thickness uniformity (a method for producing an optical disk according to the fourth embodiment of the present invention). In this case, the identification signal may be printed on the reflective layer 10B2 as in the third embodiment shown in FIG. 5, or the identification signal may be printed on the bonding surface side of the bonded substrate.

In the text, the BCA of a DVD disc is used.
Although the description has been made with the signal in mind, it goes without saying that an identification signal that does not comply with the format of the BCA signal can also be recorded by the method of the present invention.
Also, the radius and area to be recorded can be set arbitrarily, and are not limited to the pre-pits.

As described above, the embodiment of the present invention has the following effects. (1) A barcode-like identification signal equivalent to BCA can be recorded at low cost. (2) When applied to a laminated disc such as a DVD, the advantage of BCA is that the barcode cannot be removed unless the disc is removed. (3) When applied to a single disk such as a CD, the identification signal does not appear unless the reflective film is completely removed. Therefore, it is possible to erase the BCA signal by removing the protective film and reforming the reflective film. The drawback of the BCA signal forming method by laser trimming can be compensated. (4) Even in the case of the signal reading method in which the main signal is reproduced from the surface of the disk substrate on which the prepits are formed, the identification signal may be printed after forming the reflective film. (5) Since different discriminating signals can be recorded on disc substrates made from the same master disc, discriminating signals for each disc, master disc, title, lot, etc. can be recorded.
It can be used to prevent duplication of optical discs, illegal use of software, and prevention of illegal copying.

[0023]

As described above, according to the disc of the present invention, an optical disc provided with an identification signal which has a function equivalent to that of BCA and which cannot be easily duplicated without using laser trimming is provided. be able to.

[Brief description of drawings]

FIG. 1 is an embodiment diagram showing a configuration of an optical disc of the present invention.

FIG. 2 is a waveform diagram including a recording signal for forming a BCA on the optical disc of the present invention and a reproduction signal reproduced from the BCA.

FIG. 3 is a diagram for explaining a BCA signal in a reproduced signal.

FIG. 4 is a process diagram illustrating a method of forming a BCA signal of an optical disc according to the present invention.

FIG. 5 is a process chart for explaining a BCA signal forming method for an optical disc of the present invention.

[Explanation of symbols]

10, 10A, 10B Optical disk 10a Center hole 10A1, 10B1 Light transmissive substrate 10A2, 10B2 Reflective layer 10A3 Adhesive layer 10A4 Laminated light transmissive substrate (Laminated substrate) 10A6, 10B5 Part 10b Specific area (lead-in area) 10B3 Protection Layer 10c Data area 10e Light blocking identification signal, BCA (identification pattern light blocking layer)

Claims (5)

(57) [Claims] 1. A data area in which main data is recorded,
A reflective layer, an adhesive layer, and a sticker are provided on a light-transmissive substrate that is provided on the inner circumference side of this data area and has a specific area in which sub-data used during the reproduction operation of the main data is recorded. An optical disc in which laminated substrates are sequentially laminated, and an identification pattern different for each disc is provided on a part of the specific region provided on the light-transmissive substrate as a light-shielding substance.
An optical disk, characterized in that an identification pattern light-shielding layer formed of high quality is provided between the reflection layer and the reflection layer. 2. A data area in which main data is recorded,
A reflective layer and a protective layer are sequentially provided on a light-transmissive substrate that is provided on the inner peripheral side of this data area and has a specific area in which sub-data used during the reproduction operation of the main data is recorded. A laminated optical disc, which has a light- blocking identification pattern that is different for each disc on a part of the specific area provided on the light-transmissive substrate .
An optical disk, characterized in that an identification pattern light-shielding layer formed of high quality is provided between the reflection layer and the reflection layer. 3. A data area in which main data is recorded,
A reflective layer, an adhesive layer, and a sticker are provided on a light-transmissive substrate that is provided on the inner circumference side of this data area and has a specific area in which sub-data used during the reproduction operation of the main data is recorded. An optical disc formed by sequentially laminating laminated substrates, wherein a disc on the reflective layer corresponding to the specific region provided on the light transmissive substrate has a different identification for each disc.
An optical disc, wherein an identification pattern light-shielding layer having a pattern formed of a light-shielding substance is provided between the adhesive layer. 4. A data area in which main data is recorded,
A reflective layer and a protective layer are sequentially provided on a light-transmissive substrate that is provided on the inner peripheral side of this data area and has a specific area in which sub-data used during the reproduction operation of the main data is recorded. An optical disc formed by stacking the discs, each disc having a different identification on a part of the reflection layer corresponding to the specific region provided on the light transmissive substrate.
An optical disc, wherein an adhesive layer light shielding layer is provided between the protective layer and an identification pattern light shielding layer having a pattern formed of a light shielding material . 5. The optical disc according to claim 1, wherein the identification pattern light-shielding layer is a light-shielding layer formed of a bar code pattern.