JP2004030922A - Optical recording medium - Google Patents

Abstract

An optical recording medium having excellent security is provided.
A light-transmitting substrate having a plurality of tracks formed with pit rows having irregularities corresponding to encrypted information and having at least a reflective layer made of a light-reflective substance and a label surface. In an optical recording medium in which information is read out by detecting the uneven shape of the pit row by using a laser beam irradiated from the opposite side of the light-transmissive substrate on which the pit row is formed, Is recorded in a predetermined area of the track, and management information 2 based on the key information is printed on the label surface.
[Selection diagram] Fig. 1

Description

The present invention relates to an optical recording medium in which minute irregularities are formed in accordance with information and which reads information by detecting a change in the irregularities using a laser beam, and more particularly to an optical recording medium suitable for information security. It is about media.

(2) Conventionally, there is an optical recording medium on which information is read out by forming minute irregularities on a light-transmitting substrate in accordance with information and detecting a change in the irregularities using a laser beam. For example, optical disks are generally widely used because such optical recording media can be mass-produced at low cost. Since this optical disk has a large recording capacity, it has recently been used as a recording medium for recording document information, image data, program software and the like, such as a CD-ROM, and has been widely used taking advantage of the above advantages. .

By the way, when document information, image data, program software, and the like are recorded on the optical disk in this way, it is difficult for the user to check the contents and purchase it. For example, in the case of a general printed matter, it is possible to check the contents by reading the contents of the books arranged at the storefront or reading the headings, but the contents of the documents and image data recorded on the optical disk can be checked. If the same thing is to be performed, it is necessary to prepare a large number of optical disk reproducing devices and display devices for displaying the contents, which is not practical in terms of cost and space. Further, since a plurality of persons handle the optical disk, the optical disk may be damaged, and the reproduction may not be performed, and there is a problem in terms of merchandise management.

Therefore, in recent years, information such as document data, image data, and program software has been encrypted so that it cannot be reproduced by a normal reproducing apparatus. There is an optical disc on which information that can be reproduced by the reproducing apparatus is recorded. The above-mentioned encrypted information can be reproduced if there is specific key information, and the above-mentioned encryption method and key information for deciphering the key information are reduced to a specific number to manufacture an optical disk. It should be almost impossible to unravel. In this way, the optical disk itself can be distributed at a very low price or free of charge. Then, if there is any information in the recorded information that the user is interested in, the selling source provides the key information for decrypting the favorite information for a fee. By doing so, the user can check the contents and purchase only the information that he / she likes, and the store does not have problems such as cost and space.

By the way, the above-mentioned optical disc is manufactured using a stamper in which concavities and convexities are formed in advance, and the number of optical discs manufactured with the same stamper is reduced to about several hundred in order to prevent encryption from being broken. We adopt a small-volume molding technique of limiting. However, such a method loses the merit of the optical disc that the cost can be reduced by mass production. Conversely, if a large number of optical disks are manufactured from the same stamper in order to reduce the manufacturing cost, the possibility that the encryption will be broken increases.

In such an optical disk, a magnetic layer is provided on the side opposite to the surface from which light is read, and the information in this magnetic layer is encrypted, or is not scanned by an optical head of a general reproducing apparatus. Also, there has been proposed an optical disc in which a barcode is recorded on an outer peripheral end portion and the barcode is used as encryption. These optical discs have the advantage that they can be mass-produced, but they need to be provided with a second detecting means other than the information reading optical head on the reproducing apparatus side, and have the disadvantage that they cannot be reproduced by existing reproducing apparatuses.

In view of the above, the present invention has been made in view of the above points. An encryption is prepared in order to prevent the contents information of the optical disc from being reproduced by a normal reproduction method, and key information for decrypting the encryption is based on the key information. An object of the present invention is to provide an optical recording medium excellent in security by enabling normal reproduction only after collation of management information.

Therefore, an invention for achieving the above object is to provide a method of forming a pit row having a concave-convex shape corresponding to encrypted information on a light-transmitting substrate formed over a plurality of tracks by forming at least a reflective layer made of a light-reflective substance. A light from which the information is read by detecting the unevenness of the pit row by using a laser beam emitted from the opposite side of the light-transmitting substrate on which the pit row is formed. In the recording medium,
Key information for decrypting the encrypted information is recorded in a predetermined area of the track, and management information based on the key information is printed on the label surface. recoding media. ”.

Another object of the present invention is to provide an optical recording medium characterized in that the key information is recorded in a lead-in area.

As described above, according to the optical recording medium of claims 1 and 2 of the present invention, key information for decrypting encrypted information is recorded in a predetermined area of the track, and Since the management information based on the key information is printed on the label surface, an encryption is prepared so that the contents information of the optical disc cannot be reproduced by the normal reproduction method, and the key information for decrypting the encryption and the information based on the key information are used. Normal reproduction is enabled only after collation of the management information, so that an optical recording medium with excellent security can be provided.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a view showing the appearance of an optical disk according to an embodiment of the present invention, and shows the optical disk viewed from a label surface (surface opposite to a signal reading surface).

Information recorded on the optical disk 1 shown in FIG. 1 by pits having irregularities is recorded, for example, in an encrypted form so that it cannot be decrypted by a normal reproducing apparatus. Information 2 is recorded. The management information 2 is determined according to a decoding method for decoding information recorded on the optical disc 1, and key information (decoding information) for decoding information is specified by the management information 2. You can. That is, the optical disc 1 cannot decode recorded information without key information. This key information is recorded in a key information recording area provided in a predetermined area in the optical disc 1.

In the present embodiment, the key information is recorded in the manufacturing process after injection molding of the substrate of the optical disc in order to make the key information of the optical disc 1 different for each disc. Specifically, pits corresponding to key information are formed by laser light, or a plurality of key information is prepared in advance and pits are formed according to the key information, and pits other than key information to be used are formed. The uneven shape is destroyed after molding of the optical disc so that the information recorded by the uneven shape cannot be reproduced.

Hereinafter, examples of these optical disks will be described.

FIG. 2 is a diagram showing a cross-sectional view in the track direction of the key information recording area of the optical disc according to the first embodiment of the present invention. The shape of the pit when viewed from the signal reading surface (substrate side) is shown on the lower side of FIG.

The optical disc 11 shown in FIG. 1 is configured such that a reflective layer 13 made of a light-reflective material and a protective film 14 are laminated in this order on a substrate 12 on which pits 15 and 16 having uneven shapes corresponding to information are formed. I have.

ピ ッ ト The pits 15 out of the pits 15 and 16 formed in the key information recording area shown in the figure are pits formed by injection molding using a stamper, and do not have a rim in the periphery of the uneven shape. The pit 16 is a pit formed by cutting with a laser beam in a manufacturing process after the injection molding of the substrate 12, and has a shape having a rim 17 in a peripheral portion of the uneven shape.

基板 As a material of the substrate 12, a material whose shape is changed by irradiation with strong laser light is used, and for example, a light-transmissive resin such as polycarbonate used in CD is used.

The reflective layer 13 is made of a metal or an alloy having a high light reflectivity such as aluminum, gold, or copper, and the metal or alloy layer is composed of one layer. The protective film 14 is made of an ultraviolet curable resin.

FIG. 3 is a diagram showing a cross-sectional view in the track direction of a key information recording area of the optical disc according to the second embodiment of the present invention. As in FIG. 2, the lower side shows the shape of the pit when viewed from the signal reading surface (substrate side). The same parts as those of the optical disk 11 are denoted by the same reference numerals.

The optical disk 21 shown in FIG. 3 breaks the concave and convex shape of the pits 15 formed by injection molding using a stamper so that the information recorded by the concave and convex shape cannot be reproduced, so that the key information can be reproduced one by one. Different. The optical disk 21 is configured such that a reflective layer 13 made of a light-reflective material and a protective film 14 are laminated in this order on a substrate 22 on which pits 15 are formed, similarly to the optical disk 11 described above.

The pits 15 recorded in the key information recording area shown in FIG. 3 are formed when the substrate 22 is injection-molded by a stamper, and some of the pits 15 are originally irradiated by laser light. It has been destroyed to a state where it is impossible to detect the uneven shape of. The deformed portion 23 destroyed by the laser beam has a rim 24 on the outer peripheral portion, and an inner portion surrounded by the rim 24 is wrinkled. The generation of the wrinkles is caused by the difference between the expansion rate when the substrate 22 is deformed by the irradiation of the laser beam and the expansion rate of the reflective layer 13. Therefore, if such a recording operation is performed using laser light on the substrate 22 having no reflective layer 13, it is possible to form the deformed portion 23 without wrinkles.

In the figure, all the irregularities of the pits 15 formed on the substrate 22 are destroyed, but if the information by the pits 15 cannot be reproduced, only a part of the pits 15 may be destroyed. In addition, as shown in the figure, it is possible to break not only two pits but also a plurality of pits in the track direction.

As described above, the optical disks 11 and 21 are made of materials generally used in conventional optical disks, and have substantially the same structure.

Next, a method for producing the optical disks 11 and 21 will be described.

The optical discs 11 and 21 are created in substantially the same manner as a conventional CD (compact disc) except for recording key information. That is, a photosensitive film such as a photoresist is formed on the surface of the glass master disk, and the photosensitive film is irradiated with a laser beam to perform exposure and development to form pits. Here, in the case of the above-mentioned optical disk 11, exposure is not performed on a portion to be a key information recording area, and no pit or pit row is formed. In the case of the optical disk 21, a plurality of different pieces of key information are recorded in the key information recording area. The position where the key information recording area is provided is arbitrary, such as a lead-in area or the head position (header or the like) of the program software. The position is recorded in an area or the like.

Next, after a conductive film is formed on the photosensitive film on which the pits are formed, a stamper is formed by plating, and the stamper is mounted on an injection molding machine, and the substrate 12 or the substrate 22 is formed of a resin such as polycarbonate. . Then, a reflective layer 13 made of the above metal or alloy is vapor-deposited on the substrates 12 and 22, and an ultraviolet curable resin or the like is formed on the reflective layer 13 by spin coating.

Next, recording of key information on the optical disks 11 and 21 will be described. Recording (destruction) of key information is performed using a recording device dedicated to recording. Note that the recording of the key information is performed in the manufacturing process after the injection molding of the substrates 12 and 22 before the formation of the reflection layer 13 or after the formation of the reflection layer 13 and before the formation of the protection film 14 and the protection film 14. May be performed in any of the steps, such as after the formation of.

First, the case of the optical disk 11 will be described.

FIG. 4 shows the state of the pits in the key information recording area of the optical disk 11 created as described above before the key information is recorded. As shown in the figure, a pit 15 having an uneven shape is formed on a substrate by injection molding, and an unrecorded area 31 where the pit 15 is not formed is included in an information track in which the pit is formed. Some have. The key information is recorded in the unrecorded area 31 where the pits 15 are not formed, and becomes the key information recording area.

When such an optical disc is mounted on a recording apparatus, a laser beam with an output of, for example, 5 mW is irradiated from the substrate 12 side to reproduce a formed pit and detect an area where a signal is not detected for a certain period. Thus, the unrecorded area 31 is searched. When the unrecorded area 31 is searched, the laser beam output is increased to about 300 mW, the tracking of the recording apparatus is fixed, and the pit 16 based on the key information is formed in the unrecorded area 31. As described above, the pits 16 formed by the laser beam have a concave shape like the pits 15 formed by the injection molding, but a convex rim is formed on the outer periphery thereof, and the appearance is different from the pits 15 ( (See FIG. 2). However, by appropriately selecting the laser beam output and the linear velocity at the time of pit formation, it is possible to set the level to a level that does not cause a problem in signal quality.

That is, since the recording of the key information is performed in the manufacturing process after the molding of the optical disk substrate, the output of the laser beam used for recording and the linear velocity at the time of recording can be set arbitrarily regardless of the standard as long as the substrate does not significantly deform. Therefore, it is possible to appropriately set an optimum laser light output that provides the best signal quality. The laser beam for forming the pits 16 may be irradiated from either the signal reading surface side or the signal surface side.

When the key information is recorded in this manner, the management information 2 corresponding to the key information is printed on the label surface, and the optical disc 11 is created.

Next, the case of the optical disk 21 will be described.

(4) In the key information recording area of the optical disk 21 before recording the key information (before pit destruction), a plurality of pits having an uneven shape corresponding to a plurality of different pieces of key information are formed. As the recording device on which the optical disk 21 is mounted, a recording device having the same laser beam output as the optical disk 11 is used.

(4) When such an optical disk is mounted on the recording apparatus, a laser beam having an output of, for example, 5 mW is irradiated from the substrate 22 side to search the key information recording area while reproducing the formed pits 15. When the key information recording area is searched, the laser light output is increased to 300 mW, and the pits other than the specific one or two types of key information are destroyed so that they cannot be reproduced as shown in FIG.

Here, when the deformed portion 23 is formed before the reflective layer 13 is formed, since the light reflectance of the substrate 22 is low, a reproducing operation for searching for a key information recording area and a recording operation for forming the deformed portion 23 are performed. Must be performed without transmitting through the substrate 22. For this reason, the laser beam is irradiated from the pit side to the substrate 22 on which the reflective layer 13 is not formed.

(4) After the pits 15 are destroyed in this way, the management information 2 is printed on the label surface according to the key information constituted by the pits 15 that are correctly read, and the optical disc 21 is created.

Since the optical disc 21 destroys the recorded pits 15, the recording accuracy is not required as compared with the case where the pits are recorded as in the optical disc 11, but the storage capacity of the optical disc is the same as the destroyed pits 15. Is reduced. However, the key information recording area in which the pits 15 are destroyed is small in view of the storage capacity of the entire optical disk, so there is no problem that the storage capacity is reduced.

In the optical disc 21, any means other than the laser beam can be used as long as the pit 15 can be destroyed. For example, the pit may be flawed with a stylus to make it impossible to reproduce. . When flaws are formed in the pits in this manner, the pits 15 are preferably destroyed before forming the protective film 14 and after the injection molding of the substrate 12 or after the formation of the reflective layer 13.

Based on these methods, the optical disks 11 and 21 were prepared using CDs (compact disks).
<Example 1>
A stamper having an unrecorded area 31 where no pits 15 are formed from the specific address of the CD and having a length of about 1 mm is formed. Polycarbonate is injection-molded by an injection molding machine using the stamper to form a substrate 12. An optical disk was formed by forming an aluminum reflective layer 13 of 60 nm and an ultraviolet resin protective film 14 of 10 μm thereon. This optical disk was mounted on a recording device equipped with a semiconductor laser having a wavelength of 780 nm as a light source, and the pit 15 was reproduced at an output of 5 mW to search for an unrecorded area 31. When the unrecorded area 31 was searched, the pit 16 was formed in the unrecorded area 31 by increasing the laser beam output. At this time, the laser beam output on the pit was 20 mW / μm 2 and the linear velocity was 0.5 m / s.

After recording the key information, "ABC-123" is printed with a rubber stamp as management information 2 on the inner peripheral portion of the label surface, and then the aluminum reflective layer 13 is formed to have a thickness of 60 nm and the protective film 14 is formed to have a thickness of 10 μm in the same manner as a normal CD. Thus, an optical disk 11 was prepared.

(4) When this optical disk 11 was mounted on a normal reproducing apparatus and reproduced, the key information could be detected, but the encrypted information could not be correctly decoded and the information could not be reproduced.

Next, the key information based on the printed management information "ABC-123" was attached to the reproducing apparatus provided with the decoding table in which the decoding method was determined by inputting the key information. However, the information has been correctly decoded and the information can be reproduced.
<Example 2>
A key information recording area is provided at a specific address of a CD, a stamper in which a combination of ten numbers is recorded by pits 15 is created in the key information recording area, and polycarbonate is injection-molded by an injection molding machine using the stamper. An optical disk was formed by forming an aluminum reflective layer 13 of 60 nm and an ultraviolet resin protective film 14 of 10 μm on the substrate 22. This optical disk was mounted on a recording device equipped with a semiconductor laser having a wavelength of 780 nm as a light source, and the pit 15 was reproduced at an output of 5 mW to search for a key information recording area. When the key information recording area was searched, the laser output was increased, and the concave and convex shape of the pit containing information of eight of the ten numbers was destroyed. The laser output at this time was 10 mW / μm ² and the linear velocity was 0.5 m / s.

After recording the key information, "ABC-123" is printed with a rubber stamp as management information 2 on the inner peripheral portion of the label surface, and then the aluminum reflective layer 13 is formed to have a thickness of 60 nm and the protective film 14 is formed to have a thickness of 10 μm in the same manner as a normal CD. As a result, an optical disk 21 was prepared. When this was mounted on a normal reproducing apparatus and reproduction was performed, the above eight numbers could not be read, and only two numbers could be read.

In addition, as in the case of the optical disk 11, information cannot be reproduced by a normal reproducing apparatus, and is mounted on a reproducing apparatus having a decoding table based on key information, and is based on printed management information "ABC-123". When the key information was input to the playback device, the playback was normally performed.

As described above, the optical discs 11 and 21 of this embodiment cannot be reproduced without key information. As described above, the management information 2 corresponding to the key information is printed on the label surface of the optical disc. This management information 2 is used, for example, as follows. When the user wants to use the software recorded on the purchased optical disk, the user notifies the creator (or distributor) of the optical disk of management information (for example, ABC-123) printed on the optical disk together with the software usage fee. Then, the creator is provided with the key information corresponding to "ABC-123" to the user, and the user can use the software using the key information.

In addition, since the owner of the optical disk can be specified by using this management information, for example, the original optical disk used to create the pirated optical disk is specified by the management information, and the optical disk used as the pirated optical disk is identified. There is also an effect that the owner can be found and illegal copying of the optical disc is prevented.

When reproducing the optical disks 11 and 21, a decoding method or the like that requires key information is required. The decryption method and the key information can be arbitrarily configured, but the decryption method and the key information may be configured so that the information is correctly reproduced by inputting the key information. For example, since the optical disks 11 and 21 of this embodiment are manufactured using a common stamper, information other than the key information may be set to a decoding method that can be reproduced by a normal reproducing device. In this case, for example, the recorded information can be reproduced by collating the key information recorded on the optical disk with the key information specified by the management information.

Since the decoding method for reproducing the information on the optical disks 11 and 21 is different from the decoding method of a normal reproducing apparatus, the decoding method is performed by a reproducing apparatus or a hardware (computer or the like) using the information of the optical disk. It is necessary to prepare a conversion method. This decoding method is, for example, recorded on an optical recording medium so that it can be reproduced even by ordinary decoding, supplied by another recording medium such as a magnetic disk, or prepared in a reproducing apparatus. Just do it. The key information does not need to be different for each optical disk, but can be different for several, several tens, or several hundreds of optical disks.

Further, a plurality of key information recording areas may be provided on the optical disc. For example, if a plurality of software are recorded on the optical disc, a number corresponding to the software or more may be provided.

The present invention is, of course, applicable to other optical recording media such as a card type and a tape type as well as an optical disk.

FIG. 1 is a diagram illustrating an appearance of an optical disc according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a cross-sectional view in a track direction of a key information recording area of the optical disc according to the first embodiment of the present invention. FIG. 7 is a diagram showing a cross-sectional view in the track direction of a key information recording area of an optical disc according to a second embodiment of the present invention. FIG. 3 is a diagram showing a key information recording area of the optical disc in FIG. 2 before recording the key information.

Explanation of reference numerals

1,11,21 Optical disk (optical recording medium)
2 Management information 12,22 substrate (light transmitting substrate)
DESCRIPTION OF SYMBOLS 13 Reflective layer 14 Protective film 15, 16 Pit 17, 24 Rim 23 Deformation part

Claims (2)

A light-transmitting substrate having at least a reflective layer made of a light-reflective substance and a label surface on a light-transmitting substrate on which a pit row having a concave-convex shape corresponding to the encrypted information is formed over a plurality of tracks; An optical recording medium in which the information is read out by detecting the uneven shape of the pit row by a laser beam irradiated from the opposite surface side on which the pit row is formed,
Key information for decrypting the encrypted information is recorded in a predetermined area of the track, and management information based on the key information is printed on the label surface. recoding media. The optical recording medium according to claim 1,
An optical recording medium, wherein the key information is recorded in a lead-in area.

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