JP2007242181A - Optical disk recording medium and optical disk manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent manufacturing of a pirated disk in an optical disk recording medium to be a ROM disk exclusive to reproduction wherein marks are formed on a reflection film by irradiation with laser light to additionally write data. <P>SOLUTION: A pit transfer intermediate layer on which a pit surface is formed is provided separately from a first recording layer on a pit transfer substrate to form a multilayered disk structure and only a reflection layer of the other recording layer except the first recording layer is irradiated with the laser light to form the marks. Since a mark formation trace is not given to the substrate differently from a conventional constitution, manufacturing of the pirated disk by exposing the surface of the substrate and transferring the physical shape thereof can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disc recording medium having a plurality of recording layers on which information is recorded by pits as an optical disc recording medium, and an optical disc manufacturing method for manufacturing such an optical disc recording medium.

  As an optical disk recording medium, a read-only ROM disk, in particular, is used all over the world as a package medium since a large number of replica substrates can be manufactured in a short time by plastic injection molding from a single stamper. For example, CDs (Compact Discs), DVDs (Digital Versatile Discs), and the like are widely used as ROM disks for recording information such as music and video.

Conventionally, so-called pirated discs have been created by illegally copying the recorded data based on ROM discs sold as package media in this way, and copyright infringement has been a problem.
In general, a pirated disc is produced by producing a stamper by producing a stamper by a mastering process based on a signal reproduced from a regular disc. Alternatively, it is created by copying a signal reproduced from a regular disc to a recordable disc.

  Various techniques have been proposed to prevent the production of pirated discs. One of them is a technology for adding different identification information for each disc, for example. In this way, by adding different identification information to each disk, it is possible to construct a system in which the playback device reads the identification information and transmits it to an external server device via a network. If such a system is used, for example, when a pirated disk is created and sold, a large amount of the same identification information is detected by the server device, so that the presence of the pirated disk can be detected. Furthermore, it may be possible to specify a pirated dealer by specifying the playback apparatus that has transmitted the detected identification information.

However, it is useful for copyright protection that identification information unique to each disc is recorded so that it cannot be easily copied by a commercially available drive device.
Therefore, for example, in Patent Document 1 below, the identification information is recorded by forming a mark on the reflective film of the disk to give a slight change in reflectance. That is, in the disc described in Patent Document 1, main data (content data, management information, etc.) is recorded by a combination of pits and lands, and a slight reflection is made on a reflection film on a predetermined pit or land. By forming a mark that gives a rate change, sub data other than the main data is recorded.

The mark recording on the reflective film is performed by laser irradiation with a recording power higher than the laser power during reproduction. At this time, the change in reflectance due to the mark is made minute so as not to affect the reproduction of the main data recorded by the combination of pits and lands. That is, this prevents the sub data from being reproduced in the normal reproduction operation for the main data.
For the reproduction of the sub data itself, a separate reproduction system is provided, and a large number of such subtle reflectance change portions in the reproduction signal of the main data are sampled to obtain these integral values, for example. It can be carried out.
In this case, the position where each value of the sub data is to be inserted is determined by a predetermined algorithm predetermined between the sub data recording device side and the playback device side. Thereby, since the position where each value is recorded can be specified by using the same algorithm as used at the time of recording in a regular playback device, the identification information as the sub data can be properly played back.

Japanese Patent No. 3454410

By the way, in the above description, it is assumed that a pirated disc is created from a reproduction signal of a regular ROM disc. However, as another method, a stamper is created by transferring the physical shape of the substrate of the ROM disc as it is. A technique to do this is also conceivable.
Specifically, the shape of the pits and lands formed on the substrate is exposed by peeling the disc cover layer and the reflective film from the substrate. Then, by physically transferring the concavo-convex shape thus exposed, the content recorded on the disk is duplicated.

  In the disc described in Patent Document 1, identification information for each disc is recorded by a mark formed on the reflective film. According to this, the physical transfer method that requires the cover layer and the reflective film to be peeled off from the substrate as described above cannot transfer even the mark (identification information) formed on the reflective film. Therefore, it is considered that the production of pirated discs can be prevented.

  For example, in general, the reflective film is formed so as to have very strong adhesion to the substrate by sputtering or the like, and the film thickness is also very thin, about several tens of nm. For this reason, it is extremely difficult to scrape the substrate without damaging the uneven shape of the substrate. Therefore, a solvent is used to peel off the reflective film. However, when the solvent is used in this way, the reflective film itself is dissolved, so that even the marks as sub-data formed there are transferred. As a result, the manufacture of pirated discs is thought to be prevented.

However, recording of marks on the reflective film as described above is performed by irradiation with a relatively high output laser. Such high-power laser irradiation may cause, for example, thermal expansion or the like due to an increase in the medium temperature at a mark recording portion, which may deform the substrate.
In other words, there is a possibility that a mark that should be formed only on the reflective film is physically transferred to the substrate, and further, this substrate is physically transferred so that the main data and the sub data are duplicated. There is a possibility of being.

This will be described with reference to FIG.
First, FIG. 13A shows a cross-sectional structure of an optical disk recording medium in which marks are formed on the reflective film as described above.
As shown in the figure, the optical disk recording medium in this case includes a pit transfer substrate 101 having a pit surface formed by stamper transfer, and a reflective film 102 formed on the pit surface of the pit transfer substrate 101. Further, at least a cover layer 103 laminated on the upper layer is provided. The cross-sectional shape of the unevenness formed between the pit transfer substrate 101 and the reflective film 102 is a portion where main data is recorded by a combination of pits and lands.
As described above, a mark as sub-data is recorded on the reflection film on a predetermined pit or land (X in the figure). In the example shown in the figure, an example is shown in which marks are recorded on a reflective film on a predetermined land.

As described above, at the time of recording a mark as sub-data, the reflective film 102 is irradiated with a relatively high-power laser, so that the mark formation portion X is deformed due to thermal expansion accompanying the temperature rise. May occur.
Along with this deformation, a concave recess is transferred to the surface of the pit transfer substrate 101 in contact with the reflective film 102. That is, in this case, when the cover layer 103 and the reflective film 102 are peeled and the substrate 101 is exposed, as shown in FIG. 13B, only the reflective film 102 is formed on the surface of the substrate 101. The concave shape corresponding to the power mark is transferred.

The transferred concave portion becomes a portion where the reflectance slightly decreases with respect to other land portions. In other words, a replica substrate created by transferring the concave shape of the substrate 101 as it is is a reproduction of the mark as sub data as it is.
Then, if the reflective film and the cover layer are laminated in the same manner as the normal manufacturing process for such a replica substrate, a pirated disc in which the main data and the sub data recorded on the regular disc are copied exactly is manufactured. Can be made.

Therefore, in the present invention, in view of the above problems, an optical disc recording medium is configured as follows.
That is, the optical disk recording medium of the present invention includes a pit transfer substrate on which a pit surface is formed, and a reflective film formed on the pit surface of the pit transfer substrate to form a first recording layer. In addition, it is provided to form a pit surface in the upper layer of the reflective film in the first recording layer, is soft enough to transfer the pit pattern, and can retain the shape of the transferred pit pattern A pit transfer intermediate layer formed of a denatured material that can be changed to be hard enough to have a pit surface, and a reflective reflecting film formed on the pit surface of the pit transfer intermediate layer An optical disc recording medium provided with at least one recording layer in which information is recorded by pits by providing at least one set of film and
Only the reflective film in the recording layer other than the first recording layer is formed with a mark accompanying the laser beam irradiation.

In the present invention, the optical disk manufacturing method is as follows.
That is, a pit transfer substrate on which a pit surface is formed and a reflective film formed on the pit surface of the pit transfer substrate are provided to form a first recording layer, and the first recording It is provided to form a pit surface in the upper layer of the reflective film in the layer, it is soft enough to transfer the pit pattern, and it changes so hard that it can hold the shape of the transferred pit pattern There is at least one set of a pit transfer intermediate layer formed of a possible alteration material and having a pit surface formed thereon, and a reflective film having transparency formed on the pit surface of the pit transfer intermediate layer. By providing more than one set, a disc generating step of generating an optical disc recording medium provided with two or more recording layers on which information is recorded by pits is provided.
Then, by irradiating the recording layer other than the first recording layer in the optical disc recording medium generated by the disc generating step with a laser beam, the other recording layer other than the first recording layer An information recording step for forming a mark associated with the irradiation of the laser beam only on the reflection film in FIG.

In this way, in the present invention, the pit transfer intermediate layer having the pit surface is provided, and the reflective film is formed on the pit surface to form the recording layer. In addition to the recording layer, a recording layer in which information is recorded by pits is formed to realize a multi-layer disc.
In addition, according to the present invention, marks as sub-data are formed only on recording layers other than the first recording layer. That is, according to this, since no mark is formed on the reflective film of the first recording layer, it is possible to prevent the substrate from being deformed due to the formation of the mark as in the prior art. That is, in this respect, it is possible to prevent the production of a pirated disk by performing the physical transfer by exposing the uneven shape of the substrate.
However, in the case of such a configuration, there is a possibility that deformation of the cross-sectional shape corresponding to the mark formation may be given to the pit transfer intermediate layer by forming the mark. However, as this pit transfer intermediate layer, a denatured material that is soft enough to transfer the pit pattern as described above and can be changed to be hard enough to hold the shape of the transferred pit pattern. Is selected. If such a denatured material is used, the pit transfer shape can be maintained even if the thickness is reduced. That is, by selecting such a denatured material, the thickness of the pit transfer intermediate layer can be made considerably thinner as compared with, for example, a pit transfer substrate.
Since the thickness can be reduced in this way, peeling off the reflective film formed on the pit transfer intermediate layer without damaging the shape of the pit surface below the same results in peeling off the reflective film on the pit transfer substrate as well. It can be much more difficult than the case. In other words, this makes it very difficult to produce a pirated disk by exposing the pit surface of the pit transfer intermediate layer and performing physical transfer including mark formation marks.

  As described above, according to the present invention, the recording layer on which information is recorded by the pits is formed, and the mark accompanying the laser beam irradiation is formed on the reflective film of the recording layer, for example, information for copyright protection or the like. Can be effectively prevented from being produced for the optical disk recording medium to which is added.

  Further, according to the optical disk manufacturing method of the present invention, an optical disk recording medium that can effectively prevent the manufacture of pirated disks can be manufactured.

Hereinafter, the best mode for carrying out the invention (hereinafter referred to as an embodiment) will be described.
FIG. 1 is a cross-sectional structure diagram of an optical disc 10 as an optical disc recording medium according to an embodiment.
The optical disk 10 according to the embodiment is a read-only ROM disk, and specifically adopts a disk structure and format compliant with a disk called a Blu-Ray Disc (registered trademark). . The optical disk 10 of the embodiment is a multi-layer disk having a plurality of recording layers on which information is recorded by pits (and lands).

  In FIG. 1, an optical disc 10 has a pit transfer substrate 1 having a pit surface formed on one side thereof as shown in the figure, and a first reflective film formed on the pit surface side of the pit transfer substrate 1. 2, a pit transfer intermediate layer 3 formed on the first reflective film 2 and having a pit surface formed on the surface opposite to the contact surface with the first reflective film 2, and the pits of the pit transfer intermediate layer 3 A second reflective film 4 formed on the surface and a cover layer 5 made of, for example, an ultraviolet curable resin, are formed on the second reflective film 4.

First, the pit transfer substrate 1 is a transparent resin substrate made of, for example, polycarbonate or acrylic, and the pit surface is provided with an uneven cross-sectional shape as shown in the figure. The concave cross section is a pit, and the other portion where the pit is not formed (convex cross section) is a land.
On the pit surface, information is recorded by a combination of these pits and lands, specifically, the respective lengths of the pits and lands.

  The first reflective film 2 is also provided with an uneven cross-sectional shape corresponding to the uneven cross-sectional shape on the pit surface of the pit transfer substrate 1. At the time of reproduction, the laser light is irradiated from the direction of the objective lens shown in the figure so as to be focused on the first reflective film 2, so that the reflected light corresponding to the uneven shape of the first reflective film 2 is reflected to the objective lens. It returns to the side as signal light. On the side of the sub data recording device 20 and the reproducing device 50 described later, information recorded by the pits (and lands) of the pit transfer substrate 1 is detected based on the reflected light from the first reflecting film 2 of the irradiated laser light. can do.

Here, from the viewpoint that the information recorded on the pit surface in this way is detected based on the reflected light of the laser beam irradiated on the reflective film formed thereon, the pit surface and the pit surface are detected. It is assumed that the recording layer is formed with the reflective film to be formed.
Specifically, the recording layer formed by the pit surface of the pit transfer substrate 1 and the first reflective film 2 formed thereon is called a first recording layer L0 as shown.

  In this case, since the pit surface is formed on the pit transfer intermediate layer 3, the sectional shape of the pit surface of the pit transfer intermediate layer 3 can be used as the second reflective film 4 formed on the pit surface. Concave and convex shapes corresponding to are given. That is, a recording layer is also formed by the pit surfaces of the pit transfer intermediate layer 3 and the second reflective film 4 formed thereon. The recording layer formed by the pit surface of the pit transfer intermediate layer 3 and the second reflective film 4 formed thereon is called a second recording layer L1 as shown in the drawing.

In this case, since the laser beam for reproduction is irradiated from the objective lens side shown in the figure, the first recording layer L0 should be irradiated with the laser beam through the second recording layer. For this reason, the second reflective film 4 needs to have a certain degree of transmittance. On the other hand, for the first recording layer L0, the reflected light obtained from the first reflective film 2 via the second reflective film 4 must be obtained as signal light. Should be made higher.
Considering these, it is necessary to ensure sufficient reflectivity and transmittance as a reflective film used in a multilayer ROM disc such as the optical disc 10. In this example, a Blu-ray disc is assumed, and blue laser light (for example, wavelength λ = 405 nm) is used as the laser light. In this example, for example, a silver alloy is used for the first reflective film 2 and the second reflective film 4 as a material capable of obtaining sufficient reflectance and transmittance for laser light irradiation in such a wavelength region. Yes.

In addition, when similarly reading the signals recorded on the first recording layer L0 and the second recording layer L1, it is necessary that the reflected light from them has the same amount of light.
In this case, since each reflective film (2, 4) is made to use a common material as described above, the amount of light reflected from each reflective film is adjusted by adjusting the film thickness. Is done.
That is, the film thickness of the first reflective film 2 is set so that a high reflectance (low transmittance) can be obtained in comparison with the second reflective film 4. Further, the film thickness of the second recording layer 4 is set so as to have a low reflectance (high transmittance) as compared with the first recording layer 2. As a result, when the laser beam is focused on the first reflection film 2, the amount of reflected light reflected by the reflection film 2 and transmitted through the second reflection film 4, and the laser beam on the second reflection film 4 are obtained. Adjustment is made so that the amount of reflected light obtained by being reflected by the reflective film 4 when the focus is achieved is equal.

Here, since the pit transfer intermediate layer 3 is formed with a pit surface, the material is selected so that the pit pattern shape transferred by the stamper can be maintained as will be described later in the disk manufacturing process.
That is, use a denatured material that is soft enough to transfer the pit pattern during film formation and can be changed to be hard enough to retain its shape when the pit pattern is transferred. Has been.
In the case of the present embodiment, a UV curable material (ultraviolet curable material) is used as such a denatured material. More specifically, for example, an ultraviolet curable resin such as a resin is used.

In this case, as the pit transfer intermediate layer 3, as will be described later, a UV curable resin as a denatured material is applied onto the first reflective film 2 by, for example, a spin coating method, On the other hand, after the pit pattern is transferred by the stamper, it is formed by irradiating with ultraviolet rays from the pit transfer substrate 1 side and curing.
Since the alteration material can be hardly altered in this way, the shape of the transferred pit pattern can be effectively maintained. Therefore, the pit transfer intermediate layer 3 can be formed very thin as compared with the pit transfer substrate 1 formed of polycarbonate or the like.

The pit transfer intermediate layer 3 formed in the multilayer disk in this way needs to be thin as described above for the convenience of the disk standard.
For example, in the case of the Blu-ray disc assumed in the case of this example, the thickness of the disc is determined to be about 1.2 mm according to the standard. That is, it is required that the disc thickness be within the standard range of about 1.2 mm regardless of whether the recording layer is a single layer or a multilayer.
In the optical disk 10 in this example, the thickness of the pit transfer substrate 3 is set to about 1.1 mm. Therefore, in the case of a multilayer disc, it is necessary to form the recording layer other than the first recording layer and the cover layer 5 with the remaining thickness of about 0.1 mm. Therefore, the pit transfer intermediate layer 3 to be formed in the multi-layer disc needs to be formed much thinner than the pit transfer substrate 1, for example. In this case, the thickness of the pit transfer intermediate layer 3 may be at least 30 μm or less, and is set to about 25 μm, for example, in this example.

  In this embodiment, the mark M is formed on the second reflective film 4 in the second recording layer L1 by irradiating the laser beam on the optical disk 10 having the recording layers as described above. . That is, the mark M is not formed on the first reflective film 2 of the first recording layer L0 on the pit transfer substrate 1 as in the prior art, but on the reflective film in other recording layers other than the first recording layer L0. On the other hand, the mark M is formed by laser beam irradiation.

  In this manner, in the optical disc 10 of the present embodiment, for example, sub-data such as copyright protection information is not the first recording layer L0 formed by the pit surface formed on the pit transfer substrate 1 and the first reflective film 2. Recording can be performed with the mark M formed only on the other recording layer (in this case, the second recording layer L1). That is, in the optical disc 10, the mark M is not formed on the first reflective film 2 in the first recording layer L0, so that the pit transfer substrate 1 is not deformed as the mark is formed as in the prior art. be able to. That is, in this respect, it is possible to prevent the production of a pirated disk by exposing the concave and convex cross-sectional shape of the pit transfer substrate 1 and performing physical transfer.

However, in the case of such a configuration, there is a possibility that deformation of the cross-sectional shape accompanying the mark formation may be given to the pit transfer intermediate layer 3 by forming the mark M.
However, the pit transfer intermediate layer 3 can be made very thin by being made of a denatured material as described above. Since the thickness can be reduced in this way, peeling off the reflective film 4 without damaging the pit surface formed in the pit transfer intermediate layer 3 is the same as peeling off the reflective film 2 on the pit transfer substrate 1. It can be extremely difficult to do. That is, in this case, it is extremely difficult to produce a pirated disk by exposing the shape of the pit surface of the pit transfer intermediate layer 3 and performing physical transfer including mark formation marks. can do.
As a result, according to the optical disk 10 of the present embodiment, the production of the pirated disk can be effectively prevented.

Further, as described above, since the reflective film is formed on the pit surface so as to be firmly fixed by, for example, a sputtering method, it is conceivable to use a solvent to peel off the reflective film.
When such a solvent is used, it is relatively easy to peel off the reflective film without damaging the pit surface if the substrate is polycarbonate or other strong substrate. When the substrate is a very thin base such as the transfer intermediate layer 3, even if a solvent is used, the shape can be easily damaged during the peeling operation. In other words, this can effectively prevent the production of pirated discs by a technique using a solvent.

In particular, if a UV curable resin such as a resin is used as in the embodiment, it is possible to more reliably prevent the production of a pirated disk by removing the solvent.
That is, when an experiment was performed to peel off the reflective film using a solvent capable of melting the reflective film made of the silver alloy selected in the embodiment, it was confirmed that the resin was also melted together. That is, in this example in which a resin is used for the pit transfer intermediate layer 3 in the case of using a silver alloy as a reflection film in this way, when performing peeling using a solvent, peeling is performed while maintaining the cross-sectional shape of the pit surface. It can be even more difficult. That is, together with the difficulty of peeling due to the very thin thickness of the pit transfer intermediate layer 3 as described above, it is possible to more firmly prevent the manufacture of pirated discs by physical transfer.

Further, like the optical disc 10 of the present embodiment shown in FIG. 1, in the multilayer disc, the reflective film of the recording layer other than the first recording layer L0 on the substrate 1 (here, the second recording layer L1 in the second recording layer L1). By adding the additional data by forming the mark M to the reflective film 4), the laser power required for forming the mark M can be set low.
That is, in the optical disc 10 shown in FIG. 1, when the sub data is recorded by the mark M for the first recording layer L0 on the substrate 1, the laser beam is reflected on the reflective film 4 in the second recording layer L1. The laser power required for recording must be greater than that required for the second recording layer L1. Therefore, as in this example, additional recording of the sub data by forming the mark M on the reflective film of the recording layer other than the first recording layer L0 on the substrate 1 is necessary for recording accordingly. The laser power can be lowered.

  When a large amount of laser power is required, a high-power laser light-emitting element is naturally used. However, the higher the power of the laser light-emitting element, the larger the size and the higher the price. If the laser power is suppressed as described above, a relatively low-power element can be used as the laser light-emitting element, whereby the enlargement of the laser light-emitting element can be suppressed and the manufacturing cost can be reduced.

Next, FIG. 2 is a diagram for explaining a manufacturing process (manufacturing method) of the optical disc 10 shown in FIG.
In manufacturing the optical disc 10, the formatting step S11 in the drawing is first executed. This formatting step S11 is performed using, for example, a computer.
In this formatting step S11, a conversion operation is performed on content data (user data) to be recorded on the optical disc 10 so as to obtain a format data string according to a predetermined standard. That is, in the case of the embodiment, the conversion operation is performed so as to obtain a data string according to the Blu-ray disc standard as described later in FIG. In practice, addition of error detection codes and error correction codes to user data, interleaving processing, address information addition processing, and the like are also performed.

In the variable length modulation step S12, variable length modulation processing is performed on the data string generated in the formatting step S11. In the case of the embodiment, RLL (1, 7) PP (Parity preserve / prohibit, RLL: Run Length Limited) modulation processing and NRZI (Non Return to Zero Inverse) modulation processing are performed. The “0” “1” pattern of the data string obtained by the variable length modulation step S12 becomes a pattern of pits and lands actually formed on the optical disc 10.
Data obtained by formatting user variable data and performing variable-length modulation processing in this way is referred to as main data here.

Subsequently, the master generation step S13 is performed. The master production step S13 is performed using a mastering device.
In particular, in this master generation step S13 in this case, a master for transferring a pit pattern to be formed on each first recording layer L0 in correspondence with the generation of the optical disc 10 having two recording layers. Two sheets are produced: a first recording layer metal master D1-1 and a master for transferring a pit pattern to be formed on the second recording layer L1 (second recording layer metal master D1-2). To be done.
Specifically, in producing the first recording layer metal master D1-1, first, a photoresist is applied to the glass master. And according to the data which should be recorded with respect to the 1st recording layer L0 among the main data produced | generated in the said variable length modulation process S12 in the state which rotationally driven the glass original disc coated with the photoresist in this way. Irradiate with laser light. Thereby, an uneven pattern (that is, pits and lands) corresponding to data to be recorded on the first recording layer L0 is formed on the resist along the recording track.
Next, the resist having the pits and lands formed in this manner is developed to fix it on the glass master, and further, the surface of the master is electroplated to form the first recording layer metal master D1-1. Generate.

  In addition, for the second recording layer metal master D1-2, the data to be recorded on the second recording layer L1 among the main data generated in the variable length modulation step S12 as the laser beam irradiation to the resist. It is generated by performing the same procedure as that for generating the first recording layer metal master D1-1 except that the corresponding laser beam irradiation is performed.

Then, using the first recording layer metal master D1-1 and the second recording layer metal master D1-2 generated in this manner, the disc generation step S14 is performed.
In the disc generation step S14, first, a stamper for the first recording layer is created based on the first recording layer metal master D1-1. Similarly, a stamper for the second recording layer is generated based on the second recording layer metal master D1-2.
First, the stamper for the first recording layer is placed in a molding die, and the pit transfer substrate 1 is generated from a transparent resin such as polycarbonate or acrylic using an injection molding machine. In this case, a first reflective film 2 made of a silver alloy is formed on the pit transfer substrate 1 by, for example, sputtering or vapor deposition.

Further, a UV curable resin (resin in this case) as a denatured material is applied to the first reflective film 2 formed on the pit transfer substrate 1 so as to have a constant thickness by, for example, a spin coating method. To do. The stamper for the second recording layer is pressed there, and ultraviolet irradiation is performed from the pit transfer substrate 1 side to cure the resin as the denatured material. As a result, a pit transfer intermediate layer 3 having a pit surface as shown in FIG. 1 is provided on the first reflective film 2.
Then, after removing the stamper for the second recording layer from the pit transfer intermediate layer 3, the second reflective film 4 made of, for example, a silver alloy is sputtered on the pit surface of the pit transfer intermediate layer 3. A film is formed by vapor deposition or the like, and a cover layer 5 is coated thereon with, for example, an ultraviolet curable resin by a spin coat method or the like and irradiated with ultraviolet rays to be cured.
As a result, an optical disk recording medium having a structure in which the pit transfer substrate 1 → the first reflection film 2 → the pit transfer intermediate layer 3 → the second reflection film 4 → the cover layer 5 are stacked in this order as shown in FIG. . That is, as the first recording layer L0 and the second recording layer L1, an optical disc recording medium (hereinafter referred to as a main data recording disc D2) in which only main data generated through the variable length modulation step S12 by the formation of pits is recorded. Or simply referred to as disk D2).

Subsequently, the sub data additional recording step S15 is executed.
This sub-data appending step S15 is a step for appending, for example, sub-data as copyright protection information to the main data recording disc D2 generated in the disc generating step S14.

In the case of the present embodiment, as the sub data, serial number information that is unique to each main data recording disk D2 is recorded as actual data that is the data content portion. That is, by this, as each optical disc 10 generated by the sub-data additional recording step S15, identification information (identification number) unique to the optical disc 10 is added.
Further, in addition to the identification information as the actual data, in this case, an error correction code is also added as the sub data. By attaching this error correction code, it becomes possible to perform an error correction process on the identification information during reproduction.

As the sub data, an address section in which it is to be added is determined in advance as will be described later. In this case, since the mark M as the sub data is recorded on the second recording layer L1, at least the address section on the second recording layer L1 is set as such an address section. Further, in the section in which such sub data is to be added, each value constituting the sub data is inserted at a specific position.
In the sub data additional recording step S15, these conditions are satisfied, and laser data is irradiated to the main data recording disk D2 with the recording power to perform additional recording of the sub data by forming the mark M.
This sub data recording step S15 is performed by the sub data recording apparatus 20 described later with reference to FIG.

  In this case, only the identification information and the error correction code are included as the sub data, but other data can be added.

FIG. 3 shows the data structure of main data recorded on the optical disk 10 (main data recording disk D2) manufactured by the above manufacturing process.
First, as shown in the drawing, one recording unit called RUB is defined. One RUB is composed of 16 address units (“sector” in the figure) and two linking frames. The linking frame is provided as a buffer area between the RUBs.
One address unit in this case forms one address unit.
Each address unit is composed of 31 frames as shown in the figure. One frame is composed of 1932 channel bits of data.
In the Blu-ray disc exemplified in the embodiment, the main data is in accordance with the RLL (1, 7) PP modulation rule, and the continuous number of codes “0” and “1” (that is, the pit length and the land) The length) is limited to a length of 2T (channel bits) to 8T.
In the sync positioned at the head of each frame, a 9T continuous code that does not follow this modulation rule is inserted and used to detect a frame synchronization signal during reproduction.

FIG. 4 is a block diagram showing an internal configuration of the sub data recording device 20 for additionally recording the sub data described above to the main data recording disk D2.
As described above, as the sub data, identification information unique to each optical disc 10 is recorded as the actual data content. Therefore, the operation of the sub data recording device 20 is to record sub data with a different pattern for each optical disk 10 to be loaded.
As described above, the sub-data is recorded in advance on the main data recording disk D2, and the position for inserting each mark M is also determined in advance in this section. The sub data recording device 20 is configured to record the mark M at such a predetermined specific position.

In FIG. 4, first, the main data recording disk D2 is rotationally driven by a spindle motor 21 in accordance with a predetermined rotational drive system while being placed on a turntable (not shown). The optical pickup OP shown in the figure reads the recording signal (main data) from the disk D2 that is driven to rotate in this way.
As shown in the figure, the optical pickup OP includes a laser diode LD serving as a laser light source, and an objective lens 22 for condensing and irradiating a laser beam onto a recording layer (in particular, the second recording layer L1 in this case) of the disk D2. A photodetector PD for detecting reflected light based on the laser beam irradiation from the disk D2 is provided.

  Reflected light information detected by the photodetector PD in the optical pickup OP is converted into an electric signal by the IV conversion circuit 23 and then supplied to the matrix circuit 24. The matrix circuit 24 generates a reproduction signal RF, a tracking error signal TE, and a focus error signal FE based on the reflected light information from the IV conversion circuit 23.

The servo circuit 25 controls the tracking drive signal TD and the focus drive signal FD output from the biaxial drive circuit 26 based on the tracking error signal TE and the focus error signal FE from the matrix circuit 24. These tracking drive signal TD and focus drive signal FD are supplied to a biaxial mechanism (not shown) that holds the objective lens 22 in the optical pickup OP, and based on these signals, the objective lens 22 moves in the tracking direction, It is driven in the focus direction.
In the tracking servo / focus servo system using the servo circuit 25, the 2-axis drive circuit 26, and the 2-axis mechanism, the servo circuit 25 performs control based on the tracking error signal TE and the focus error signal FE, thereby irradiating the disk D2. Control is performed so that the beam spot of the laser beam traces the pit row (recording track) formed on the disk D2 and is maintained in an appropriate focus state.

  The reproduction signal RF generated by the matrix circuit 24 is supplied to a binarization circuit 27 where it is converted into binarized data of “0” and “1”. The binarized data is supplied to a synchronization detection circuit 28 and a PLL (Phase Locked Loop) circuit 29.

  The PLL circuit 29 generates a clock CLK synchronized with the supplied binarized data, and supplies this as an operation clock for each necessary unit. In particular, the clock CLK is also supplied as an operation clock for the binarization circuit 27 and a synchronization detection circuit 28, an address detection circuit 30, and a sub data generation circuit 31, which will be described below.

The synchronization detection circuit 28 detects the sync pattern inserted for each frame shown in FIG. 3 from the supplied binary data. More specifically, the frame synchronization detection is performed by detecting the 9T section that is the sync pattern in this case.
The frame synchronization signal is supplied to necessary units such as the address detection circuit 30.

  The address detection circuit 30 detects address information based on the frame synchronization signal and the supplied binary data. The detected address information is supplied to a controller (not shown) that performs overall control of the sub data recording device 20 and used for a seek operation or the like. The address information is also supplied to the recording pulse generation circuit 33 in the sub data generation circuit 31.

The sub data generation circuit 31 includes a recording pulse generation circuit 33 and a RAM (Randam Access Memory) 32 as shown in the figure. The sub data generation circuit 31 is a sub data to be recorded on the disk D2 based on the input sub data, the address information supplied from the address detection circuit 30 and the clock CLK supplied from the PLL circuit 29. A recording pulse signal Wrp for recording data in the form described later with reference to FIG. 5 is generated.
The operation of the sub data generation circuit 31 will be described later.

The laser power control unit 34 controls the laser power of the laser diode LD in the optical pickup OP based on the recording pulse signal Wrp output from the sub data generation circuit 31. Specifically, the laser power control unit 34 in this case performs control so that the laser output by the reproduction power is obtained when the recording pulse signal Wrp is at the L level. Further, when the recording pulse signal Wrp is at the H level, control is performed so that the recording power is obtained.
When laser irradiation is performed with the recording power under the control of the laser power control unit 34, when this laser light is irradiated so as to be focused on the second reflective film 4, A mark M is formed in the portion irradiated with the laser beam. Thus, the sub data is recorded on the disk D2 by the mark M formed on the reflective film 4.

FIG. 5 is a diagram for explaining a recording form of sub data to be realized by the operation of the sub data generating circuit 31 described above.
FIG. 5 shows an example in which “0” is recorded as a 1-bit code constituting sub data and “1” is recorded.
First, as a method for expressing a code, an odd number (odd) and an even number (even) adjacent to each other for a predetermined length of land existing in the main data are considered as one set. For each adjacent odd-numbered and even-numbered pair of lands having a predetermined length, the code “0” is recorded when the odd-numbered mark M is recorded, and “1” is recorded when the even-numbered mark M is recorded. ".
In the example of FIG. 5, the mark M is recorded on the land of 5T as the predetermined length land.

  Although the recording target of the mark M is a land here, the mark M can be formed on the pit portion.

In this case, one address unit, which is one address unit, is assigned as a section to be assigned to recording of 1-bit code constituting the sub data.
That is, as shown in this figure, marks are recorded in a form expressing the same code for each pair of adjacent odd-numbered and even-numbered predetermined-length lands in one address unit.
Specifically, when the code “0” is recorded, the mark M is recorded only on the odd-numbered land of the predetermined length land in one address unit as shown in the figure.
When the code “1” is recorded, the mark M is recorded only on the even-numbered land of the predetermined length in one address unit.

Although details will be described later, at the time of reproduction, the reproduction signal RF is sampled for every adjacent odd-numbered and even-numbered pairs of predetermined length lands in one address unit, and the value of the reproduction signal RF sampled at the odd-numbered unit is used. The value of the reproduction signal RF sampled at the even number is subtracted (“odd-even”).
Here, assuming that the reproduced signal level of the recorded mark M is lower than the reproduced signal level in the unrecorded portion of the mark, in the case of the code “0” in which the mark M is recorded only in the odd number, such “odd− When the “even” operation is performed, a negative value is ideally obtained for each adjacent predetermined length land. That is, by integrating the value of “odd-even” calculated for each adjacent predetermined length land in this way, a negative value can be obtained reliably and detected.
On the other hand, in the case of the code “1” in which the mark M is recorded only in the even number, the value of “odd-even” calculated for each adjacent predetermined length land is ideally a positive value. Therefore, by integrating this, a positive value can be reliably obtained and detected.

  Here, as described above, the same recording pattern is repeatedly recorded over a specific section, and at the time of reproduction, one value is determined based on the plurality of the same recording patterns. The change in the reflectance given by is small and can be made a foot. As described above, since the reflectance change accompanying the recording of the mark M can be made minute, the recorded mark M can be prevented from affecting the binarization processing of the main data.

With respect to other codes constituting the sub data, the mark M is recorded by the same method as described above.
That is, in this case, the sub-data is recorded over the same number of address units as the codes constituting it.
The section for recording the sub data (hereinafter also referred to as a sub data recording target section) is determined in advance between the sub data recording apparatus 20 and the reproducing apparatus. Therefore, the sub data recording apparatus 20 is configured to perform the above-described recording of the mark M over a plurality of address units as the sub data recording target section determined in advance.

Here, in the above recording method, it should be noted that when the mark M to be recorded on the predetermined length land is recorded on the edge portion, the binarization of the main data is appropriately performed. There is a possibility that it will disappear. That is, when the mark M is recorded on the edge portion of the land having the predetermined length in this way, the reflectance tends to decrease correspondingly in the mark recording portion. Therefore, an incorrect land length (or pit length) in the binarization process. ) May be detected.
Therefore, the mark M is recorded in the center of the land to be recorded. According to this, since the edge portion can be obtained as usual, this point is also made so as not to affect the binarization processing.

  The recording pulse generation circuit 33 in the sub data generation circuit 31 shown in FIG. 4 generates the recording pulse signal Wrp at the timing as shown in FIG. . That is, in response to the code “0”, the recording pulse signal Wrp that is at the H level only in the center portion of the odd-numbered predetermined length land is generated. In correspondence with the code “1”, the recording pulse signal Wrp which becomes the H level only in the central portion of the even-numbered predetermined length land is generated.

The configuration and operation for realizing the recording technique described above will be described with reference to FIGS.
First, as described above, the recording of the sub data is performed in a predetermined sub data recording target section on the disc D2. In particular, in the case of the present embodiment, the additional recording of the sub data by the mark formation is performed not on the first recording layer L0 but on the other recording layer, so that the second recording layer is used as the sub data recording target section. A predetermined address section on L1 is set.

Here, when the mark M is recorded only in the odd-numbered or even-numbered land of the predetermined length in each address unit in the sub-data recording target section thus determined, as described above, It is necessary to grasp the contents of the main data in each address unit in the data recording target section.
Therefore, in the sub data generation circuit 31 shown in FIG. 4, the contents of the main data for each address unit in the recording target section are stored in the RAM 32 in advance.

FIG. 6 shows the data structure in the RAM 32.
First, the illustrated address indicates address information of each address unit in the sub data recording target section. For each address, the contents of main data recorded in each address unit are stored.
For confirmation, the sub data recording apparatus 20 is an apparatus used on the manufacturer side of the disk D2 (optical disk 10). Therefore, the contents of the main data actually recorded on the disk D2 can be stored in the RAM 32 as described above.

  The RAM 32 further stores the value of sub data to be recorded at the address corresponding to the address. Each value of the sub data is stored in the RAM 32 by the recording pulse generation circuit 33. The recording pulse generation circuit 33 stores each value of sub data supplied from the outside in the RAM 32 in order from the head address in the sub data recording target section.

In this way, the recording pulse generation circuit 33 can specify a land portion of a predetermined length in the main data and further specify the odd number and even number according to the data content stored in the RAM 32.
At the same time, by referring to the value of the sub-data stored in correspondence with the address as described above, it is possible to identify the odd-numbered and even-numbered land of the specified predetermined length land to which the mark M should be inserted. .
Specifically, when the value stored in association with the address is “0”, as shown in FIG. 5, the odd-numbered predetermined length land in the address unit of the address. In this case, the mark M is to be inserted, and if it is “1”, it can be recognized that it should be inserted evenly.
Further, in this case, the mark M should be inserted into the central portion of the recording target land as described above. Therefore, after specifying the recording target land as described above, the recording pulse signal Wrp which becomes the H level at the timing when the mark M is recorded in the central portion of the land is generated.

As a specific example of generation of such a recording pulse signal Wrp, first, ALL0 data based on the number of channel bits for one address unit is prepared. Then, a data string in which the code “1” is inserted at the timing specified as described above may be generated for the ALL0 data. That is, as a data string for one address unit, a data string in which only the bit position where the mark M is to be inserted is set to “1” and all other bits are set to “0”.
Based on such a data string, the recording pulse generation circuit 33 supplies the laser power control unit 34 with a recording pulse signal Wrp that becomes H level only at the timing of an appropriate mark recording position as shown in FIG. can do.

Next, the sub data recording operation performed in the sub data recording device 20 will be described in more detail with reference to the flowchart of FIG.
First, in step S101, the disk D2 is loaded. In step S102, sub data is input. The sub data input to the sub data recording device 20 is supplied to the sub data generation circuit 31 as shown in FIG.
As described above, the sub data input here is data including identification information and an error correction code unique to each disk D2 (optical disk 10).
Here, the input of the sub data is performed after the loading of the disk D2, but these may be mixed.

In step S103, each value of the sub data is stored for each address.
That is, in the operation of step S103, each value of the sub data inputted by the recording pulse generation circuit 33 in the sub data generation circuit 31 is stored for each address in the RAM 32 as shown in FIG. Corresponds to the action.

In step S104, the address value N is set to the initial value N0.
Step S104 is an operation for setting the value of the internal counter to the initial value N0 when the recording pulse generation circuit 33 performs an operation for generating a data string for each address as described below.

  In step S105, an operation for determining the value of the sub data to be recorded at the N address is performed. That is, as the operation of step S105, the recording pulse generation circuit 33 sets the value “0” associated with the corresponding address based on the counter value among the sub-data values stored in the RAM 32 corresponding to the addresses. Determine “1”.

When it is determined that the value of the sub data is “1”, the recording pulse generation circuit 33 inserts “1” at the position of the even-numbered central portion of the predetermined length land in the main data in the N address. The generated data string is generated (step S106).
In other words, as a result, the data string by the number of channel bits for one address unit is “1” only at the timing of the center of the even-numbered predetermined length land as described above, and all other codes are “0”. A data string is generated.
On the other hand, when it is determined that the value of the sub data is “0”, the recording pulse generation circuit 33 sets “1” at the position of the odd-numbered central portion of the predetermined length land in the main data in the N address. A data string into which is inserted is generated (step S107). In other words, as a result, the data string by the number of channel bits for one address unit becomes “1” only at the timing of the center of the odd-numbered predetermined length land as described above, and all other codes are “0”. A data string is generated.
As can be understood from the above description, such a data string is generated by the recording pulse generation circuit 33 based on the contents of the main data stored in the RAM 32 corresponding to each address. This can be done by specifying a long land and a bit position that is the center of the land.

When the data string for one address unit is generated in this way, the recording pulse generation circuit 33 determines whether or not the address is completed (S108). That is, it is determined whether or not the generation of the data string has been completed for all the address units in the sub data recording target section. The operation in step S108 is performed by the recording pulse generation circuit 33 determining whether or not the counter value set as the initial value N0 in the previous step S104 has reached a predetermined value.
If a negative result is obtained because the counter value has not reached the predetermined value, the address value N is incremented by 1 (step S109), and then the process returns to the previous step S105. As a result, the operation for generating the data string is performed for all address units in the sub-data recording target section.

If it is determined in step S108 that the counter value has reached the predetermined value and the address ends, sub-data recording starts in step S110.
In response to the start of recording of the sub data, first, an operation of seeking to the head address of the sub data recording target section in the second recording layer is performed (step S111). In the seek operation in step S111, for example, a controller that performs overall control of the sub data recording device 20 controls each necessary unit based on predetermined address information of the sub data recording target section on the second recording layer L1. Can be done.

Then, in response to the seek operation to the head address of the sub-data recording target section as described above, the sub-data generation circuit 33 generates the data string generated for each address unit by the operations of the previous steps S106 and S107. Is generated and output to the laser power controller 34 (step S112). The recording pulse signal Wrp based on this data string is generated based on the timing of the clock CLK so as to be synchronized with the main data to be reproduced.
The output of the recording pulse signal Wrp is triggered by the fact that the information of the head address of the recording target section is supplied as the address information supplied from the address detection circuit 30.

As described above, as the recording pulse signal Wrp generated based on the data string by the recording pulse generation circuit 33, a signal that becomes H level at an appropriate timing as shown in FIG. 5 is obtained. Therefore, the laser power control unit 34 controls the laser output of the laser diode LD from the reproduction power to the recording power based on the recording pulse signal Wrp, so that the disc D2 corresponds to the value of the input sub data. The mark M can be recorded at an appropriate position.
At this time, an address section on the second recording layer L1 is set as a sub data recording target section in which such mark recording is performed. As a result, the mark M as the sub data is formed on the second reflective film 4 of the second recording layer L1 as shown in FIG.

  Although the sub data is input from the outside, a circuit for generating a new serial number is provided every time the disk D2 is loaded, and the sub data based on the identification information input from this circuit is stored in the RAM 32. It can also be.

  In addition, although explanation by illustration is omitted, the contents of the main data to be recorded are the same. For the disc D2 having the same title, the main data stored in the RAM 32 is recorded with the same contents and the sub data is recorded. However, when sub-data is recorded on a disc D2 having a different title, the content of the main data stored in the RAM 32 may be updated according to the content of the main data recorded on the disc D2. .

Next, refer to the block diagram of FIG. 8 for the configuration of the playback device 50 that plays back the optical disc 10 of the present embodiment in which the sub data is additionally recorded by forming the mark M as described above. To explain.
In FIG. 8, only the part related to the reproduction of sub data is mainly extracted and shown, and the configuration of the demodulation system in the latter stage of the binarization process is omitted as the configuration of the reproduction system of the main data.

In the reproducing apparatus 50, the optical disk 10 is rotationally driven by the spindle motor 2 in accordance with a predetermined rotational driving method while being placed on a turntable (not shown). In this case as well, the optical pickup OP shown in the figure reads the recording signal (main data) from the optical disk 10 that is rotationally driven.
Although not shown, the optical pickup OP in this case also has a laser diode serving as a laser light source, an objective lens for condensing and irradiating the laser light on the recording layer of the optical disc 10, and the objective lens in the tracking direction and focus. There are provided a biaxial mechanism for displacing in the direction, a photodetector for detecting reflected light based on the laser light irradiation from the optical disk 10, and the like.
For confirmation, the laser beam applied to the optical disc 10 in the reproducing apparatus 50 is based on the reproducing power that is considerably lower than the recording power.

The reflected light information detected by the photodetector in the optical pickup OP is converted into an electric signal by the IV conversion circuit 53 and then supplied to the matrix circuit 54. The matrix circuit 54 generates the reproduction signal RF based on the reflected light information from the IV conversion circuit 53.
Although not shown, the signals generated by the matrix circuit 54 include a tracking error signal TE and a focus error signal FE. These are supplied to a servo circuit (not shown) and used for tracking servo and focus servo control operations, respectively.

The reproduction signal RF generated by the matrix circuit 54 is supplied to the binarization circuit 55 and is also branched and supplied to an A / D converter 61 described later.
The binarization circuit 55 converts the supplied reproduction signal RF into binary data “0” “1”. The binarized data is supplied to the PLL circuit 58, the synchronization detection circuit 59, and the address detection circuit 60.
The binarized data is also supplied to a detection pulse generation circuit 62a in the detection pulse generation unit 62 described later.

The PLL circuit 58 generates a clock CLK synchronized with the supplied binarized data, and supplies this as an operation clock for each necessary unit. In particular, the clock CLK in this case is also supplied to the detection pulse generation circuit 62a (not shown).
The synchronization detection circuit 59 detects the sync portion inserted for each frame shown in FIG. 3 from the supplied binary data. More specifically, the frame synchronization detection is performed by detecting the 9T section that is the sync pattern in this case.
The frame synchronization signal is supplied to each necessary unit including the address detection circuit 60.

  The address detection circuit 60 detects address information from the supplied binary data based on the frame synchronization signal. The detected address information is supplied to a controller (not shown) that performs overall control of the playback apparatus 50 and used for a seek operation and the like. The address information is also supplied to the detection pulse generation circuit 62a in the detection pulse generation unit 62.

  For confirmation, the optical pickup OP, the IV conversion circuit 53, the matrix circuit 54, the binarization circuit 55, the PLL circuit 58, the synchronization detection circuit 59, and the address detection circuit 60 described so far are as follows. This portion is also used when reproducing the main data recorded on the optical disc 10. In other words, these units share the structure of the main data reproduction system when reproducing the sub data.

The detection pulse generation unit 62 indicates a detection point corresponding to the mark M recording method, which is determined in common with the previous sub data recording device 20 in reproducing the identification information as sub data. A detection pulse signal Dp is generated.
In the detection pulse generation unit 62, a detection pulse generation circuit 62a and a RAM 62b are provided. The detection pulse generation circuit 62a generates the detection pulse Dp based on the information stored in the RAM 62b. The generated detection pulse signal Dp is supplied to the A / D converter 61.

The A / D converter 61 is supplied with the reproduction signal RF from the matrix circuit 54. The A / D converter 61 samples the supplied reproduction signal RF at a timing indicated by the detection pulse signal Dp and supplies the value to the sub data detection circuit 63.
The sub data detection circuit 63 performs a predetermined operation on the value supplied from the A / D converter 61 to detect each value of the sub data. In other words, for example, in this case, each value of the sub data is detected based on the result of the calculation corresponding to “odd-even” described above.
The sub-data value detection operation performed by the detection pulse generator 62, the A / D converter 61, and the sub-data detection circuit 63 will be described later.

The value of the sub data detected by the sub data detection circuit 63 is supplied to an ECC (Error Correcting Code) circuit 64.
In this case, the sub data includes identification information and an error correction code. The ECC circuit 64 reproduces the identification information by performing error correction processing based on the error correction code in the sub data.

The reproduced identification information is supplied to the host computer 56 shown in the figure.
The host computer 56 sends commands to a controller (not shown) that performs overall control of the playback apparatus 50 to instruct various operations. For example, a command for instructing reproduction of main data recorded on the optical disc 10 is transmitted. In response to this, the main data reproduced from the optical disc 10 is binarized by the binarization circuit 55, and then demodulated (RLL1-7PP demodulation), error correction processing, etc. in a demodulation system (not shown). It will be supplied to the host computer 56.
The host computer 56 is provided with a network interface 57 for performing data communication via a required network. As a result, the host computer 56 can perform data communication with an external device, particularly the management server 70 shown in the figure, via a predetermined network such as the Internet.

The sub data value detection operation performed in the playback apparatus 50 having the above configuration will be described with reference to FIG.
FIG. 9 shows the recording state of the mark M when one address unit on the optical disc 10 is assigned “0” and “1” as the value of 1-bit sub data. ing. For the sake of illustration, this figure shows a case where pits and lands as main data are formed in the same pattern.

First, as described above, as sub-data, in this case, 1-bit information is assigned to each address unit in a predetermined sub-data recording target section in the second recording layer L1 of the optical disc 10. To be recorded.
In this case, as a method for expressing the code, “0” is defined when the mark M is recorded in the odd-numbered land of the predetermined length, and “1” is defined when the mark M is recorded in the even-numbered land. . That is, as shown in the figure, when the code is “0”, the mark M is recorded only in the odd-numbered lands of a predetermined length in the address unit. When the code is “1”, the mark M is recorded only in the even-numbered lands of a predetermined length in the address unit.

Here, if the portion where the mark M is recorded is a portion where the reflectance slightly decreases, the waveform of the reproduction signal RF slightly decreases at the portion where the mark M is recorded as shown in the figure. Will do.
In the reproduction of the sub data, an operation for determining each value based on such a slight change in reflectance at the mark recording portion is performed.

  As described above, each mark M is recorded on the center portion of the predetermined land when the sub data is recorded. Since the mark M is recorded at the center of the land in this way, as can be seen with reference to the waveform of the reproduction signal RF shown in this figure, the level at the center of the land where the mark M is recorded is only at the center. The waveform of the edge portion can be obtained as usual. As a result, the binarization of the main data can be prevented from being affected as described above.

Here, according to the above description, when the code is “0”, the value of the reproduction signal RF slightly decreases only in the odd-numbered predetermined length land. When the code is “1”, the value of the reproduction signal RF slightly decreases only in the even-numbered predetermined length land.
Therefore, in this case, in determining each value of the sub-data assigned to each address unit, the value of the reproduction signal RF decreases in either the odd-numbered or even-numbered direction for the predetermined length land in the address unit. What is necessary is just to detect whether it is.

A decrease in the value of the reproduction signal RF in the mark recording portion can be detected by, for example, obtaining a difference from the value of the reproduction signal RF in the mark unrecorded portion.
At this time, as described above, when the code is “0”, only the odd number is recorded, and when the code is “1”, the mark M is recorded only in the even number, in other words, when the code is “0”. It can be seen that the even number is always an unrecorded portion, and the odd number is always an unrecorded portion when "1".
From this fact, the value of the reproduction signal RF is decreased by either “odd” or “even” by performing the calculation by “odd-even” for the odd number (odd) and the even number (even) adjacent to each other (mark M Is recorded).
Specifically, if this “odd-even” is a negative value, it is understood that the value of the reproduction signal RF at the odd number is decreased, and therefore the mark M is recorded at the odd number. . On the contrary, if “odd-even” is a positive value, the even-numbered value is decreased, and it can be seen that the mark M is recorded in the even-numbered.

However, in practice, a noise component is superimposed on the reproduction signal RF. As described above, the decrease in the value of the reproduction signal RF in the mark recording portion is very small, and there is a possibility of being buried in such a noise component. Therefore, it is difficult to reliably determine the value if the detection by the “odd-even” is performed only for even-numbered pairs of adjacent lands having a predetermined length.
For this reason, as a sub-data reproduction operation, the “odd-even” value calculated for each odd-numbered and even-numbered pair adjacent to each other as described above is integrated and assigned to the address unit based on this integrated value. The 1-bit value thus determined is determined. By doing in this way, the value of subdata can be detected more reliably.

  By the way, in order to calculate “odd-even” as described above, it is necessary to sample the value of the reproduction signal RF obtained at the central portion of odd and even, that is, both odd-numbered and even-numbered predetermined length lands. is there. As a signal for instructing the sampling timing for calculating the “odd-even”, the detection pulse generator 12 shown in FIG. 8 generates a detection pulse signal Dp in the drawing.

Here, as described above with reference to FIG. 9, the detection pulse signal Dp for calculating “odd-even” as described above is an H level only at the center of a predetermined length land obtained in the main data. It is sufficient to generate the following signal.
In the generation of the detection pulse signal Dp, the main data recorded in the sub data recording target section on the optical disc 10 is generated in the same manner as the generation of the recording pulse signal Wrp in the case of the sub data recording apparatus 20 described above. The corresponding timing may be generated from the contents of.

  However, since the reproducing apparatus 50 is not used on the disc manufacturing side as in the case of the sub data recording apparatus 20, the contents recorded on the optical disk 10 cannot be stored in the apparatus in advance. . Therefore, in the case of the reproducing apparatus 50, the main data of the sub-data recording target section is read from the loaded optical disk 10, and stored in the apparatus to be used for generating the detection pulse signal Dp.

As a memory for storing the main data of the sub-data recording target section read out in this way, the reproducing apparatus 50 is provided with a RAM 62b in the detection pulse generation unit 62 shown in FIG. As shown in FIG. 10, the data structure stores main data read corresponding to each address.
In the detection pulse generation circuit 62a in the detection pulse generation unit 62, the same applies as in the case of the previous recording pulse signal Wrp generation based on the contents of the main data in the recording target section stored in the RAM 62b. A data string that is “1” only at the timing and “0” for all others is generated. Then, a detection pulse signal Dp based on the data string generated in this way is generated and supplied to the A / D converter 61. The A / D converter 61 samples the value of the reproduction signal RF at the timing indicated by the detection pulse signal Dp, thereby sampling the value of the reproduction signal RF at an appropriate timing as shown in FIG. Can do.

Next, a more detailed operation at the time of sub data reproduction performed in the reproducing apparatus 50 will be described with reference to the flowchart of FIG.
First, when the optical disk 10 is loaded in step S201, in step S202, the operation of storing main data for each address is performed for the sub-data recording target section on the optical disk 10.
Here, when the optical disk 10 is loaded, for example, in response to an instruction from the host computer 56 shown in FIG. 8, a seek is made to the start address of the sub-data recording target section determined in advance with the sub-data recording apparatus 20. Then, an operation of reading main data recorded in the recording target section is executed. For the main data read out in this way, the detection pulse generation circuit 62 a shown in FIG. 8 converts the binarized data supplied from the binarization circuit 55 to each address based on the address information supplied from the address detection circuit 60. And stored in the RAM 62b.

In step S203, the address value N is set to the initial value N0.
In step S203, when the detection pulse generation circuit 62a generates a data string indicating the sampling timing of the reproduction signal RF for each address unit as described below, the value of the internal counter is set to the initial value. This is an operation to set to N0.

In step S204, a data string in which “1” is inserted at the central position of the predetermined length land in the main data in the N address is generated.
The operation in step S204 is performed with reference to the content of main data stored in the RAM 62b by the detection pulse generation circuit 62a. In other words, the detection pulse generation circuit 62a has “1” only for the position of the central portion of the predetermined length land in the main data stored in association with the N address in the RAM 62b, and “0” for all other data. To generate a data string. For example, in this case, since the mark M is recorded on the 5T land, only the third bit position in the 5T section is “1”, and all other data is “0”. Create a sequence.
By such an operation, a data string indicating a sampling point in the address unit of N addresses is generated.

When the data string indicating the sampling points for one address unit is generated in this way, the detection pulse generation circuit 62a determines whether or not the address has ended (S205). That is, it is determined whether or not the generation of the data string has been completed for all the address units in the sub data recording target section. The operation in step S205 is performed by the detection pulse generation circuit 62a determining whether or not the counter value set as the initial value N0 in the previous step S203 has reached a predetermined value set in advance.
If a negative result is obtained that the counter value has not reached the predetermined value, the address value N is incremented by 1 (step S206), and then the process returns to step S204. As a result, the operation for generating the data string is performed for all address units in the sub-data recording target section.

If it is determined in step S207 that the counter value has reached the predetermined value and the address has ended, reproduction of sub data is started in step S208.
In response to the start of reproduction of the sub data, an operation of seeking to the head address of the sub data recording target section in the second recording layer is performed (step S209). The seek operation in step S209 is performed on the controller (not shown) described above based on the address information of the sub-data recording target section in the second recording layer L1 determined in advance by the host computer 56 shown in FIG. 8, for example. Realized by giving instructions.

Then, in response to the seek operation to the head address of the sub-data recording target section as described above, the detection pulse generation circuit 62a is based on the data string generated for each address unit by the operation of the previous step S204. A detection pulse signal Dp is generated and output to the A / D converter 61 (step S209). The generation of the detection pulse signal Dp based on the generated data string is performed based on the timing of the clock CLK so as to be synchronized with the main data to be reproduced.
The output of the detection pulse signal Dp is triggered by the fact that the information of the start address of the recording target section is supplied as the address information supplied from the address detection circuit 60.

In the subsequent step S210, an operation of detecting the value of the sub data by a calculation based on “odd-even” for the value sampled based on the detection pulse signal Dp is performed.
The operation in step S210 is performed by the A / D converter 61 and the sub data detection circuit 63.
That is, the A / D converter 61 samples the value of the reproduction signal RF supplied from the matrix circuit 54 at a timing indicated by the detection pulse signal Dp supplied from the detection pulse generation circuit 62a. Then, the value is output to the sub data detection circuit 63.
The sub-data detection circuit 63 subtracts the even-numbered value from the odd-numbered value for the value supplied from the A / D converter 61 to thereby change the “odd-even” described in FIG. Perform the operation. Then, the value of “odd-even” calculated in this way is integrated for each address unit, and the value of the sub data is detected based on the integrated value.

  Each value of the sub data detected in this way is supplied to the ECC circuit 64, and an error correction process based on the error correction code in the sub data is performed to reproduce the identification information. The reproduced identification information is supplied to the host computer 56 and used as information for copyright protection.

In the above description, for the sake of simplicity, the mark M as sub-data has a set of odd-numbered and even-numbered adjacent lands having a predetermined length, and a code “0” depending on where the mark M is inserted. 1 ″ is expressed, but in practice, the insertion position of the mark M is based on another algorithm such as using an M-sequence random number so that it is difficult for a third party to specify such a recording pattern. Can also be determined.
Even in this case, as long as the rules for the code representation method and the section allocated to one bit of the sub data are defined so as to be common to the sub data recording device 20 and the reproducing device 50 side. The playback device 50 can properly play back the sub data.

  In the above description, the polarity is determined based on the subtraction result between the recorded portion (formed portion) of the mark M and the unrecorded portion (unformed portion) of the mark M as “odd-even”. It is also possible to fix the reproduction signal level of a portion where the mark M is not formed to a certain value and determine the polarity based on the subtraction result between the reproduction signal level in the mark recording portion and this fixed value. . Note that the fixed value in this case should be set according to the length of the land portion to be recorded by the mark M.

  Here, as can be understood from the above description, the mark M formed on the second reflective film 4 in the optical disc 10 of the present embodiment is used for reproducing main data recorded by a combination of pits and lands. It can be recorded without affecting it. Therefore, it is possible to prevent the sub data from being reproduced only by reproducing the main data, and accordingly, the sub data recorded by the mark M on the reflection film 4 is reproduced from the optical disc 10. By copying the main data, it is possible to effectively prevent the pirated disc from being copied as it is.

Although the embodiments of the present invention have been described above, the present invention should not be limited to the embodiments described so far.
For example, in the embodiment, the optical disk recording medium of the present invention has been illustrated as having only two recording layers including the first recording layer on the pit transfer substrate 1, but the recording layer has three or more recording layers. It can also be configured.

FIG. 12 is a diagram showing an example of a cross-sectional structure of an optical disc recording medium as a modified example having three or more recording layers as described above.
The modification of FIG. 12 shows a case where three recording layers are provided. That is, in this case, in the configuration of the optical disc 10 shown in FIG. 1, the pit surface on which the third recording layer L2 is to be formed is formed on the second reflective film 4 that forms the second recording layer L1. The transfer intermediate layer 6 is provided, and the third reflective film 7 is formed on the pit surface of the pit transfer intermediate layer 6. The cover layer 5 is formed on the third reflective film 7.

In addition, the mark M as the sub data is formed on the third reflective film 7 on the third recording layer L2 located farthest from the first recording layer L0 on the pit transfer substrate 1.
Here, in the case where three or more recording layers are provided as in the example of FIG. 12 and a plurality of recording layers are provided in addition to the first recording layer L0 formed on the substrate 1, the recording layer on which the mark M is to be formed. Can be selected. When the mark M is formed on the reflective film in the recording layer farthest from the first recording layer L0 (that is, the recording layer closest to the laser beam incident side) as described above, the laser power required for forming the mark M is the highest. Can be lowered.

  For example, when such a laser power problem is not considered, the mark M is formed on the other recording layers (in this case, the second recording layer L1) except the first recording layer L0. You can also.

  Alternatively, in addition to recording the mark M only on the reflective film of any one recording layer other than the first recording layer L0 in this way, in particular, a disc having three or more layers as shown in FIG. In this case, the marks M can be formed on a plurality of recording layers other than the first recording layer L0 on the pit transfer substrate. That is, in the example of FIG. 12, the mark M is formed on both the second reflective film 4 in the second recording layer L1 and the third reflective film 7 in the third recording layer L2.

In manufacturing the optical disk having three or more recording layers as shown in FIG. 12, in the manufacturing process shown in FIG. 2, first, in the master generating step S13, the recording layer to be added is added. Additional metal masters are created for the number of pieces. That is, in the case of corresponding to the example of FIG. 12, a third recording layer metal master in which pits are formed by laser light irradiation according to main data to be recorded in the third recording layer L2 is generated. is there.
Further, in the disk generation step S14, a stamper is generated based on each metal master, and the generation of the pit transfer substrate 1 → the formation of the first reflection film 2 → the generation of the pit transfer intermediate layer 3 → the formation of the second reflection film 4 The process up to the film formation is the same, but after that, “Applying of alteration material as pit transfer intermediate layer → Formation of pit surface using stamper for the recording layer (in the case of UV curable material, hardening by UV irradiation) (Including the work) → deposition of the reflective film on the pit surface ”is performed by the number of times corresponding to the number of recording layers to be added. Then, the cover layer 5 may be formed after that.
After that, in the sub data additional recording step S15, the mark M is formed at least on the reflective film of the recording layer other than the first recording layer L0 on the pit transfer substrate 1, and the sub data is additionally recorded.
In particular, as described above, if the mark M is formed on the reflective film of the recording layer farthest from the first recording layer L0, the laser power for forming the mark M should be set to the lowest. Thus, the laser light emitting element can be reduced in size (that is, the sub data recording device 20 can be reduced in size) and the cost can be reduced.

Further, in the embodiment, the case where the denatured material selected as the material for the pit transfer intermediate layer is a UV curable resin such as a resin is exemplified, but as the UV curable resin used as such a pit transfer intermediate layer, Other UV-curable adhesive materials other than the resin can also be selected.
In addition, the altered material referred to in the present invention is not limited to such a resin, and materials belonging to other materials can also be selected. In addition, although the case of using a material that hardens in response to ultraviolet irradiation (UV curable material) is exemplified as the denatured material, it is soft enough to transfer the pit pattern and retains the shape of the transferred pit pattern If the material can be modified so as to be as hard as possible, the same effect can be obtained by using a material other than the UV curable material.

  Further, in the embodiment, the case where the optical disk 10 is a multi-layer ROM disk compliant with, for example, a Blu-ray disk has been exemplified. A reflective film formed on the pit surface of the transfer substrate to form a first recording layer, an intermediate layer having a pit surface formed on the upper layer, and a reflective film on the pit surface Can be suitably applied to any optical disc recording medium on which other recording layers are formed.

1 is a cross-sectional composition of an optical disk recording medium as an embodiment of the present invention. It is a figure for demonstrating the manufacturing process (manufacturing method) of the optical disk recording medium of embodiment. It is a data structure figure for demonstrating the data structure of the main data recorded with respect to the optical disk recording medium of embodiment. It is a block diagram which shows the structure of the sub data recording apparatus for adding sub data with respect to the optical disk recording medium of embodiment. It is a figure for demonstrating the recording form of subdata. It is a data structure figure which shows the data content which should be stored in a subdata recording device. It is a flowchart for demonstrating the recording operation of the subdata which a subdata recording device performs. It is a block diagram which shows the structure of the reproducing | regenerating apparatus which reproduces | regenerates the subdata added to the optical disk recording medium of embodiment. It is a figure for demonstrating reproduction | regeneration operation | movement of subdata. It is a data structure figure which shows the data content which should be stored in a reproducing | regenerating apparatus. It is a flowchart for demonstrating reproduction | regeneration operation | movement of the subdata which a reproducing | regenerating apparatus performs. It is a cross-section figure of the optical disk recording medium as a modification. It is a figure for demonstrating that a board | substrate may deform | transform with mark recording.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Optical disk, 1st reflective film, 3, 6 Pit transfer intermediate | middle layer, 4nd reflective film, 5 cover layer, 6 3rd reflective film, L0 1st recording layer, L1 2nd recording layer, L2 3rd recording layer , M mark, D2 main data recording disk, 20 main data recording device, 21 spindle motor, 22 objective lens, 23 IV conversion circuit, 24 matrix circuit, 25 servo circuit, 26 2-axis drive circuit, 27 binarization circuit, 28 Synchronization detection circuit, 29 PLL circuit, 30 address detection circuit, 31 sub data generation circuit, 32 RAM, 33 recording pulse generation circuit, 34 laser power control unit

Claims (6)

A pit transfer substrate having a pit surface formed thereon and a reflective film formed on the pit surface of the pit transfer substrate to form a first recording layer,
Provided to form a pit surface in the upper layer of the reflective film in the first recording layer, soft enough to transfer the pit pattern and hard enough to maintain the shape of the transferred pit pattern A pit transfer intermediate layer formed of a denatured material that can be altered to form a pit surface, a reflective film having transparency formed on the pit surface of the pit transfer intermediate layer, and An optical disc recording medium provided with two or more recording layers in which information is recorded by pits by providing at least one set according to
Marks associated with laser light irradiation are formed only on the reflective film in the recording layer other than the first recording layer,
An optical disc recording medium characterized by the above.   2. The optical disk recording medium according to claim 1, wherein the pit transfer intermediate layer is made of an ultraviolet curable resin. Only one set of the pit transfer intermediate layer and a reflective film formed on the pit surface is provided, and only two recording layers on which information is recorded by the pits are provided.
The optical disk recording medium according to claim 1, wherein: Two or more pairs of the pit transfer intermediate layer and a reflective film formed on the pit surface are provided, and three or more recording layers on which information is recorded by the pits are provided.
The optical disk recording medium according to claim 1, wherein:   The mark is formed on the reflective film in the recording layer farthest from the first recording layer among the recording layers formed by the pit surface of the pit transfer intermediate layer and the reflective film formed thereon. The optical disk recording medium according to claim 4, wherein A pit transfer substrate on which a pit surface is formed and a reflective film formed on the pit surface of the pit transfer substrate are provided to form a first recording layer, and in the first recording layer It is provided to form a pit surface in the upper layer of the reflective film, and is soft enough to transfer the pit pattern and can be changed to be hard enough to hold the shape of the transferred pit pattern. At least one or more sets of a pit transfer intermediate layer formed of a denatured material and having a pit surface formed thereon and a reflective film having transparency formed on the pit surface of the pit transfer intermediate layer A disc generating step for generating an optical disc recording medium provided with two or more recording layers in which information is recorded by pits;
Reflection at other recording layers other than the first recording layer is performed by irradiating the recording layer other than the first recording layer in the optical disc recording medium generated by the disc generating step with laser light. An information recording step for forming a mark associated with the irradiation of the laser beam only on the film;
An optical disc manufacturing method comprising:

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