JP2004192767A - Recording method for information recording medium and information control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording medium in which erasure is made impossible and formation of a pseudo mark in an ordinary drive is also made impossible by forming irreversibly identification information being intrinsic in a disk for preventing illegal copy recorded in an optical disk or the like, and provide a playing back method for the recording medium. <P>SOLUTION: In the method for playing back a phase change optical disk which is provided with land and a groove and which can rewrite information, the phase change optical disk is provided with a control region in which information can be recorded by a mark formed irreversibly at other than a recording region of user data, the irreversibly recording mark includes SYNC codes spaced evenly in the direction of recording track, and an illegal copy prevention means is provided by at least recording irreversibly the SYNC code existing in the control region. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical disk and an optical disk recording / reproducing method, and more particularly to an optical disk for recording identification information for preventing unauthorized copying and an optical disk information management method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an optical disk, unique identification information is recorded for each optical disk to prevent unauthorized copying. As conventional techniques for recording identification information, there are known methods such as BCA (Burst Cutting Area) recording used in DVDs (Digital Versatile Disks) and the like, and JP-A-9-091781, JP-A-2002-197670 and the like. Have been.
[0003]
The BCA is a method of recording the disk identification information by partially melting the reflective layer of the disk by laser trimming to form a non-reflective portion on a plurality of tracks, and arranging the non-reflective portion in a barcode shape. Japanese Unexamined Patent Publication No. 9-091781 discloses a method of recording a disc identification signal at an irreversible change of a recording film at a linear velocity lower than that of normal information recording and a higher laser power. JP-A-2002-197670 discloses that an irreversible mark is formed by recording on a recording medium with a stronger laser power than at the time of ordinary information recording, or by recording with a longer laser irradiation time than at the time of ordinary information recording. This is a method of recording identification information by providing a plurality of alternating patterns of an irreversible area and a normal area outside the user data area at a manufacturing stage.
[0004]
[Patent Document 1]
JP-A-9-091781 [Patent Document 2]
JP 2002-197670A
[0005]
[Problems to be solved by the invention]
However, since the irreversible area is formed by the above-described method, there is no fear that the mark is erased. However, the signal level of the irreversible area and the amorphous mark which is a reversible mark formed with a normal recording power by a drive after initialization are used. Since there is no difference in the signal level of the irreversible area, there is a fear that an illegal mark may be artificially formed by a normal drive on a disk having no irreversible area, and an illegally copied product may be created.
[0006]
The present invention has been made in view of the above points, and erasure is impossible by irreversibly forming disc-specific identification information for preventing unauthorized copying and the like, and a pseudo drive in a normal drive is used. An object of the present invention is to provide a recording medium on which marks cannot be formed and a method for reproducing the recording medium.
[0007]
Another purpose is to irreversibly record unique information such as address information (ID), a SYNC code, and an error detection code (EDC) to detect whether or not information in a specific sector has been rewritten. Therefore, the present invention is to provide a management information recording method and information management method.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a first object of the present invention is a method of reproducing a rewritable phase-change optical disc having lands and grooves, wherein the phase-change optical disc records user data. A management area in which information is recorded by irreversibly formed marks outside the area is provided, and the irreversibly provided marks are continuous and aligned with adjacent lands and grooves in phase. And reading the management area in a servo-off state to generate reproduction data, and reproducing the user data based on the reproduction data.
[0009]
Here, the marks formed irreversibly over a plurality of adjacent tracks in the radial direction are preferably formed in a barcode shape in the track direction. When a mark is formed in a barcode shape over a plurality of adjacent tracks, the mark is irreversibly provided even when light is applied across the land and the groove when reading is performed in a servo-off state. Are continuous in the radial direction, so that the contrast ratio does not decrease. In this case, the irreversibly formed mark may be formed continuously and integrally in the radial direction even if a phase shift occurs. At this time, if irreversible marks overlap by 80% or more between adjacent tracks, the signal level does not deteriorate.
[0010]
A second object of the present invention is a method for reproducing a rewritable phase-change optical disc having land and groove, wherein the phase-change optical disc is irreversibly formed outside a user data recording area. A management area in which information is recorded by the mark, and the irreversibly provided mark is continuously and integrally provided in adjacent lands and grooves in the radial direction, and is tracked with respect to the management area. And irradiates a reproduction light to generate reproduction data, and reproduces the user data based on the reproduction data.
[0011]
Even when tracking is performed to read a management area in which information is recorded using the irreversibly formed mark, the mark can be distinguished from a mark recorded by a normal drive for the following reason. In other words, when a mark is formed irreversibly, the mark is also recorded on a part of an adjacent track. However, since the recording is performed at a high power, recrystallization at the mark edge does not occur. On the other hand, when a mark is formed with the recording power of a normal drive, the crystallization temperature of the recording mark edge portion has reached the crystallization temperature, and the crystallization phenomenon of the amorphous portion occurs. A crystal part is formed in the part. When the mark is formed over a plurality of adjacent tracks, in the case of a recording mark formed irreversibly, as shown in FIG. As shown in FIG. 2, the reversible mark to be recorded has a lower contrast ratio than that of a recording mark formed irreversibly because the crystal part becomes a noise part, and therefore, the recording mark formed on the irreversible mark is different from the recording mark formed irreversibly. It is possible to distinguish a signal from a normally recorded reversible mark.
[0012]
If the length of the irreversibly formed recording mark in the track direction is longer than the light spot diameter λ / NA (laser wavelength of the recording / reproducing device: λ, numerical aperture of the lens: NA), light as shown in FIG. This is preferable because all the areas in the spot become recording marks formed irreversibly, so that the contrast ratio can be increased.
[0013]
A third object of the present invention is to provide a phase change optical disc having at least a groove and capable of rewriting information, comprising a management area for recording information by irreversibly formed marks outside a recording area for user data. By recording the address information (ID) irreversibly, it is possible to detect the presence or absence of rewriting from a change in the irreversibly recorded address information (ID) due to rewriting of the information. That is, the management information in the information management area is recorded by the manufacturer, and illegal copying is monitored by preventing the user from rewriting the information. Providing means for detecting the presence or absence of rewriting is effective in preventing unauthorized copying. On the other hand, irreversible recording of all management information can be performed using a write-once type information recording medium, and a phase change type or dye type optical disk can be effectively used.
[0014]
A fourth object of the present invention is to provide a rewritable phase-change optical disc having at least a groove provided with a management area for recording information with irreversibly formed marks outside a user data recording area. , SYNC code, and error detection code (EDC) are irreversibly recorded, so that the information is calculated from the reproduction signal length of the irreversibly recorded SYNC code due to information rewriting and the rewritten management information. The presence or absence of rewriting can be detected from a change in the error detection code (EDC). In other words, the management information in the information management area is recorded by the manufacturer, and attempts are made to prevent unauthorized copying by preventing rewriting by the user. It is effective for On the other hand, by irreversibly recording all the management information, the area to be recorded with higher power than normal rewriting conditions is increased, and the burden on the device side is increased, but it is effective because rewriting cannot be performed.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. A first embodiment of the recording medium according to the present invention will be described. FIG. 1 is a schematic diagram of a part of a predetermined area in which identification information is recorded according to a first embodiment of the recording medium according to the present invention.
[0016]
The recording medium of this embodiment is a disk-shaped optical recording medium, in which grooves for recording information are formed spirally or concentrically within a range from the inner periphery to the outer periphery. For example, in a predetermined range of land (L) and groove (G) on the inner circumference side of the disk, the identification information unique to the recording medium is rewritable shown in white with an irreversible area of an amorphous part shown by a black mark in FIG. It is recorded by alternate arrangement with a crystal part of a normal region (reversible region). Although not shown in FIG. 1, user information (content data) and the like are recorded in grooves and / or lands in other areas.
[0017]
When such a mark is to be formed using a normal drive, as shown in FIG. 2, identification information unique to the recording medium is written in a predetermined area of land (L) and groove (G) in a rewritable normal area ( (Reversible region) is recorded by alternate arrangement of an amorphous part indicated by a gray mark and a crystal part indicated by white.
[0018]
When an amorphous portion is reversibly formed by a normal drive, a crystal portion is formed between the amorphous mark formed on the land and the amorphous mark formed on the groove due to recrystallization of the mark edge. Would. On the other hand, when irreversible marks are formed on a medium at low linear velocity and high power, marks are also formed on adjacent tracks, but the recording marks on adjacent tracks are irreversible and recrystallized. Does not occur, and no crystal part is formed between the amorphous parts.
[0019]
When these two types of recording marks are detected by a light spot, a mark formed by a normal drive looks bright overall because of the crystal part formed between the amorphous parts, whereas the mark is irreversible. Is formed, the entire spot can be made an amorphous portion, that is, a dark portion, and the contrast can be made higher than usual.
[0020]
(Example 1)
FIG. 3 shows the structure of the phase change optical disk used in the present invention.
A substrate 11 was prepared in which irregular pits containing address information and the like and U-shaped grooves having a pitch of 0.68 μm were formed in advance on the surface of a polycarbonate resin plate having a diameter of 120 mm and a thickness of 0.6 mm. The groove width and the land-to-groove (land) width of the U-shaped groove were approximately equal to about 0.34 μm.
[0021]
This substrate 11 was disposed in a first sputtering chamber in a sputtering apparatus having a plurality of sputtering chambers and having excellent film thickness uniformity and reproducibility. Using a mixture of ZnS and SiO ₂ as a target, a (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) first dielectric layer 12 having a thickness of 55 nm was formed in an argon gas. Next, after moving the substrate to the second sputtering chamber, a GeCrN second dielectric layer 13 having a thickness of 2 nm was formed in a mixed gas of argon and nitrogen having a nitrogen content of 50 mol% using Ge ₈₀ Cr ₂₀ as a target. .
[0022]
Further, after moving this substrate to the third sputtering chamber, the recording layer 14 was formed to a thickness of 10 nm in an argon gas with a target of Ge ₃₃ Sb ₁₃ Te ₅₄ (atomic%) sintered body. Next, the substrate was moved to a fourth sputtering chamber, and a GeCrN interface layer 15 was formed to a thickness of 2 nm in a mixed gas of argon and nitrogen having a nitrogen content of 50 mol% using a Ge ₈₀ Cr ₂₀ target.
[0023]
Subsequently, the substrate was moved to the fifth sputtering chamber, and a (ZnS) ₆₀ (SiO ₂ ) ₄₀ (mol%) intermediate layer 16 having a thickness of 38 nm was formed using a mixture of ZnS and SiO ₂ as a target. Next, in the sixth sputtering chamber, an Al ₉₉ Ti ₁ (atomic%) alloy was used as a target, and an Al ₉₉ Ti ₁ first reflective layer 17 was formed to a thickness of 50 nm. Finally, Ag ₉₇ Ru ₂ Au ₁ (atomic%) was used as a target in the seventh sputtering chamber to form the Ag ₉₇ Ru ₂ Au ₁ second reflective layer 18 to a thickness of 50 nm. The laminated substrate was taken out of the sputtering apparatus, and an ultraviolet curable resin protective layer 19 was formed on the uppermost layer by spin coating.
[0024]
Similarly, on another similar substrate 11 ′, (ZnS) ₈₀ (SiO ₂ ) ₂₀ (mol%) first dielectric layer 12 ′, GeCrN second dielectric layer 13 ′, recording layer 14 ′, GeCrN Interface layer 15 ′, (ZnS) ₆₀ (SiO ₂ ) ₄₀ (mol%) intermediate layer 16 ′, Al ₉₉ Ti ₁ (atomic%) first reflection layer 17 ′, Ag ₉₇ Ru ₂ Au ₁ second reflection layer 18 ′ Then, an ultraviolet curable resin protective layer 19 'was formed. The two substrates were bonded together with the adhesive layer 20 with the UV-curable resin protective layers 19 and 19 ′ inside, and a phase-change optical disk 21 was produced.
[0025]
Next, an optical disk recording / reproducing characteristic evaluation device DDU-1000 manufactured by Pulstec (laser wavelength: 405 nm, numerical aperture of lens: 0) is applied to each track in a region having a radius of 21.5 mm to 21.7 mm of the phase change optical disk 21. .65), an irreversible mark was formed (BCA recording) on a recording pattern in which information was coded in advance, at a linear velocity of 3.0 m / s and a recording power of 10 mw. At this time, the timing of each track was adjusted so that the phase between adjacent tracks was aligned, and a mark was formed in a barcode shape.
[0026]
Next, an initialization test is repeatedly performed on the phase-change optical disk 21 having the irreversible mark formed in a barcode shape, using a Hitachi CP initializing device POP120 under the conditions of a linear velocity of 6 m / s, a power of 700 mw, and a feed amount of 36 μm. The results obtained are shown in FIG. The laser wavelength of the initialization device is 810 nm, and the spot shape is 48 μm × 1 μm. Even after the initialization has been performed ten times, the signal drop is 0.8 dB, indicating that the mark is formed irreversibly. Similarly, FIG. 5 shows the results of DC erasure repeated at a linear velocity of 3 m / s and a power of 2.5 mw using the DDU-1000 on the phase-change optical disk 21 having the irreversible mark formed in a barcode shape. Show. Even if the erasure is repeated 50 times, the signal drop is 3.1 dB, and it can be seen from this result that the mark is formed irreversibly. No signal reduction was observed in continuous reproduction at normal reproduction power.
[0027]
(Comparative Example 1)
In the same area of the phase-change type optical disk 11 created under the same conditions as in the first embodiment, a recording pattern in which information was encoded in advance using DDU-1000 was reversibly marked at a linear velocity of 5.7 m / s and a recording power of 5 mw. (Usually recorded). At this time, the timing of each track was adjusted so that the phase between adjacent tracks was aligned, and a mark was formed in a barcode shape.
[0028]
Next, FIG. 5 shows the result of DC erasure of the phase-change optical disk 21 having the irreversible mark formed in the form of a bar code at a linear velocity of 5.7 m / s and a power of 2 mW using DDU-1000. Performing the erase once reduces the signal by 25.9 dB.
[0029]
(Comparison of contrast between BCA recording and normal recording)
The reflectivity of the phase-change optical disc having bar-code-shaped marks in Example 1 and the phase-change optical disc having bar-code-marks formed in Comparative Example 1 were measured. On the other hand, the reflectivity in the amorphous portion was 5% for the optical disk of Example 1 having irreversibly formed marks, and 8.5% for Comparative Example 1 while it was the same as 17%. And Example 1 was 3.5% lower.
[0030]
Using the medium of Example 1, irreversible marks were formed by changing the linear velocity and the recording power. As a result, when the recording linear velocity of the irreversible mark is smaller than 0.25 times the linear velocity of the normal recording of 5.7 m / s, the recording of the irreversible mark is possible but its amplitude is smaller than that of the normal recording mark. . The reason is that since a material that can be crystallized even at a linear velocity of 5.7 m / s is used for the recording film, if the recording linear velocity is too slow, the recrystallized area of the recording film becomes large. . Therefore, the linear velocity for forming the irreversible mark is preferably 0.25 times or more the linear velocity for normal recording. Irreversible marks can be formed even if the linear velocity for forming irreversible marks is the same as the linear velocity for normal recording. However, in this case, when the recording power was set to a value smaller than twice the normal recording, the recorded mark became a reversible mark.
[0031]
When the relationship between the linear velocity Va for forming an irreversible mark and the recording power Pa (mW) was examined in more detail, Va was set to 0.25 to 1 times the linear velocity V for normal recording, and the recording power Pa (MW) is Pa> 2 × P × (Va / V) ^1/2
In this case, the irreversible mark was formed normally, and the signal amplitude of the irreversible mark was 1.3 times or more the signal amplitude of the normal recording mark. In the other range, even if the mark becomes a reversible mark or an irreversible mark is formed, the amplitude of the mark becomes small. further,
Pa> 2.5 × P × (Va / V) ^1/2
, The signal amplitude of the irreversible mark was 1.4 times or more the signal amplitude of the normal recording mark.
[0032]
In this embodiment, the case where both lands and grooves are used as recording tracks has been described. However, similar results were obtained when using either lands or grooves as recording tracks. In this case, the irreversible mark may be formed only on the recording track, or may be formed both on the recording track and between the recording tracks.
[0033]
(Example 2)
In the first embodiment, the case where the recording tracks are provided in the lands and the grooves, and the marks recorded in the lands and the grooves are overwritten to be substantially aligned in the radial direction and overwritten and irreversibly recorded, but in the second embodiment, the management information is recorded. A case where data is formed as an irreversible recording mark in the management information area under BCA recording conditions will be described.
[0034]
A phase change optical disk was prepared in the same manner as in Example 1. Using DDU-1000, an irreversible mark is formed in a barcode shape in the area of a radius of 21.5 mm to 21.7 mm of this phase change type optical disc, and manufactured in a "Discidentification zone" of an area of a radius of 24.0 mm to 24.1 mm. The recording power (linear velocity: 3.0 m / s, 10 mw) is obtained by a recording signal obtained by 8/16 modulating unique information such as a user code, disk identification information, key information relating to copy management of user data, and sector address information to be recorded. Irreversible marks (areas with black marks in FIG. 6) were formed by BCA recording). When a recording device made exclusively for BCA recording is used instead of the recording / reproducing characteristic evaluation device, ID information unique to the recording device may be used instead of the manufacturer ID. The phase-change type optical disc on which disc-specific information is recorded has user data (the area where the gray mark in FIG. 6 is formed) recorded by a user's recording device under normal recording conditions.
[0035]
Since the management information formed with the irreversible mark in the management area can hardly be erased as shown in FIGS. 4 and 5, when the management information is copied and recorded in another sector as shown in FIG. By incorporating sector address information and recording with irreversible marks, the sector address information at the head of the sector embedded in the recording track does not match the sector address information recorded in the main data, and the management information is duplicated Can be detected. The detection can be determined by the steps illustrated in FIG. 8 as being illegally copied.
[0036]
First, the management information written in the management information area is reproduced. The main data pointed to by the sector address information SA (n) recording the management information at this time is reproduced, and the address information ID (n) recorded so as to be included in the reproduced main data is taken out. The address information ID (n) recorded here must match the address information ID (n) uniquely determined by the sector address information SA (n) specified in advance in the system. If they do not match as in the case of ID (n ') in FIG. Next, the content of the address information ID (n) detected from the main data is compared with the content of the physical address SA (n). If the two do not match as compared with SA (n ′) in FIG. 8, it is difficult to copy and record the original management information at a sector address position SA (m) different from the first recorded sector address SA (n). It is obvious.
[0037]
By such a process, it is determined that the management information is copied by unauthorized means.
[0038]
As described above, the data copy management information of the rewritable phase-change optical disk and the key information related thereto are incorporated in the management information, and an irreversible mark is formed under the BCA recording condition, thereby reducing the hurdle for preventing unauthorized copy. Can be higher. Further, the possibility that important information is erased by mistake can be reduced.
(Example 3)
In the first and second embodiments, in the case of land / groove recording in which recording tracks are provided in lands and grooves, the case where irreversible recording is performed under the BCA recording condition in the information management area is described. Next, recording tracks are provided only in the grooves. An embodiment in the case of the above will be described.
[0040]
The same phase-change recording film as in Example 1 was laminated in reverse order on a 1.1 mm thick substrate on which a groove meandering at a constant period and recording ID information superimposed was formed. An information recording medium was produced by forming a .1 mm cover layer. The recording film of the information recording medium was initialized by an initialization device in the same manner as in Example 1. The initialized information recording medium was recorded on a recording / reproducing apparatus having a pickup having a recording laser wavelength λ = 405 nm and an objective lens NA = 0.85, a recording linear velocity = 2.5 m / s, and a bias power Pb = 0.5 mW. The main data is recorded at the management information area with normal recording power Pw1 = 2.0 mW, ID and SYNC code, and EDC at irreversible recording power Pw2 = 10 mW and reference clock T = 33 MHz, and irreversible ID, SYNC code and EDC are recorded. The recording mark was formed (FIG. 9A). When the disk was reproduced at a linear velocity of 6 m / s and a reproduction power Pr of 0.5 mW, the signal modulation was 60% in the normal recording section and 75% in the irreversible recording section.
[0041]
Next, at the linear velocity = 5.0 m / s, the bias power Pb = 2.0 mW, and the normal recording power Pw0 = 5.0 mW, the information in the management information area was rewritten (FIG. 9-b), and then reproduced. Reproduction was performed with power Pr = 0.5 mW. Since the SYNC code has a different pattern depending on the preceding information, the portion where the SYNC code is recorded cannot be erased, and a recording mark is formed in the space of the SYNC frame to be rewritten in a space. In this case, the reproduction signal length of the SYNC code differs from the modulation pattern and becomes longer. Thus, by detecting that the reproduction signal length has changed, it is possible to detect that the management information has been rewritten (falsified). In particular, when another recording apparatus is used, the stability of the servo system control of the spindle differs depending on the apparatus, and the recording start timing of the SYNC code is shifted, so that the change in the reproduction signal length is further increased.
[0042]
Further, since the error detection code (EDC) data is determined from the operation result from the main data, it is detected that the management information has been rewritten (falsified) because the error detection code (EDC) data also changes due to the rewriting. can do.
[0043]
Further, since the address information (ID) is generally set to increase continuously in the track direction, even if the data to be rewritten is recorded on another sector track, it is recorded on the meandering groove. Since the matching with the address information (ID) cannot be obtained, it is possible to detect that the management information has been rewritten (falsified).
[0044]
In the above description, all of the address information (ID), the SYNC code, and the error detection code (EDC) are performed by irreversible recording. However, irreversible recording may be performed by combining any of them. By forming an irreversible recording mark only in the unique information area of the management information area in this way, the burden on the recording laser is reduced as compared with a case where all the management information is formed by irreversible marks.
[0045]
【The invention's effect】
According to the present invention, since the unique identification information is provided irreversibly in the form of a bar code, it is possible to provide an optical disk that cannot be illegally copied and a reproducing method thereof.
[0046]
In addition, by forming information such as ID, SYNC code, and error detection code (EDC) in which specific information is recorded at a specific position using an irreversible mark, when information is rewritten (falsified), it is easily performed. It can be detected and applied to the management information area, which is effective in preventing falsification of the management information.
[Brief description of the drawings]
FIG. 1 is a diagram showing recording marks formed irreversibly.
FIG. 2 is a diagram showing recording marks normally formed by a drive.
FIG. 3 is a diagram showing a structure of a recording medium of the present invention.
FIG. 4 is a diagram showing the results of an initialization experiment.
FIG. 5 is a diagram showing the results of an erase experiment.
FIG. 6 is a diagram showing an irreversible recording management area and a normal recording user area.
FIG. 7 is a diagram showing a sector arrangement of original data and copy data.
FIG. 8 is a diagram showing steps for determining consistency of management information.
FIG. 9 is a diagram showing a data array when management information is rewritten.
[Explanation of symbols]
11, 11 'Substrate 12, 12' First dielectric layer 13, 13 'Second dielectric layer 14, 14' Recording layer 15, 15 'Interface layer 16, 16' Intermediate layer 17, 17 'First reflective layer 18 , 18 'Second reflective layer 19, 19' UV-curable resin protective layer 20 Adhesive layer 21 Phase change optical disk

Claims (6)

A method for recording information on a phase-change type optical disc using one or both of a groove and a land as recording tracks, wherein the phase-change type optical disc is irreversibly formed outside a user data recording area. A management area in which information can be recorded by the marked marks, wherein the irreversibly recorded marks include SYNC codes provided at equal intervals in the recording track direction, and at least the SYNC codes in the management area are irreversibly changed. A recording method for a phase-change optical disk, comprising: A phase-change type optical disc capable of rewriting information by using one or both of a groove and a land as a recording track, wherein at least a part of the information is irreversible outside a user data recording area. An irreversibly formed mark including at least a SYNC code provided at equal intervals in a recording track direction, wherein the irreversibly formed mark includes at least an SYNC code provided at regular intervals in a recording track direction. Recording information management method, wherein the presence or absence of rewriting of the information management area is detected based on the change in the reproduced signal length of the SYNC code. A method for recording information on a phase-change type optical disc using one or both of a groove and a land as recording tracks, wherein the phase-change type optical disc is irreversibly formed outside a user data recording area. A management area in which information can be recorded by using the marked mark, wherein the irreversibly recorded mark includes an error detection code (EDC) in sectors provided at equal intervals in a recording track direction, and at least the management area. Recording the EDC irreversibly. A phase-change type optical disc capable of rewriting information by using one or both of a groove and a land as a recording track, wherein at least a part of the information is irreversible outside a user data recording area. A management area in which information is recorded by means of a recorded mark, and a change in an error detection code (EDC) calculated from a reproduced signal of the irreversibly formed error detection code (EDC) and information after rewriting A method for managing recorded information, comprising detecting whether or not the information management area has been rewritten. A method of recording information on a phase-change optical disc, in which information is rewritable, using a groove, which is meandering at a constant cycle and in which address information (ID) is superimposed on the meandering signal, as a recording track, The optical disk has a management area in which information can be recorded by irreversibly formed marks outside the user data recording area, and the irreversibly recorded marks are stored in sectors provided at equal intervals in the recording track direction. An address information (ID), a SYNC code, and an error detection code (EDC) are included, and the address information (ID), a SYNC code, and an error detection code (EDC) in the management area are irreversibly recorded. Recording method for a phase-change optical disk. A method of recording information on a phase-change optical disc, in which information is rewritable, using a groove, which is meandering at a constant cycle and in which address information (ID) is superimposed on the meandering signal, as a recording track, The optical disk has a management area in which information can be recorded by irreversibly formed marks outside the user data recording area, and the irreversibly recorded marks are stored in sectors provided at equal intervals in the recording track direction. The phase change optical disc is rotated at a recording linear velocity lower than the recording linear velocity of the user data recording area, including the address information (ID), the SYNC code, and the error detection code (EDC). Forming the irreversible mark with a high recording laser power.

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