Optical disk and optical disk drive6633534Abstract A write-once DVD 1 has a lead-in area 4 provided inside a data area 5 where digital information on a document, image sound or the like is recorded, which includes prepits 9 holding copy managing key information for preventing unauthorized copy from a source disk to the DVD 1. The DVD has also a test area 3 provided inside the lead-in area 4, which is used for adjusting the power characteristics of the DVD 1. In the DVD 1, information recorded in the source disk can be. physically prevented from being copied into the DVD 1 without good cause on the basis of the copy managing key information recorded in the prepits 9. Claims What is claimed is: Description TECHNICAL FIELD
TABLE 1
Measured Jitter Values (Prepit Width Changed)
Prepit Width W.sub.2 Measured Jitter
0.21 .mu.m 8.7%
0.23 .mu.m 8.5%
0.25 .mu.m 8.0%
0.30 .mu.m 7.5%
0.40 .mu.m 12.0%
However, the present inventors have found that the jitter values depend on the line density (disk volume) of the DVD, as well as the prepit width W.sub.2. That is, the present inventors have experimentally found such a fact that when the groove width W.sub.1 is 0.25 .mu.m while the prepit width W.sub.2 has a smaller value of 0.18 .mu.m, the jitter value is lowered to 8% if the line density is 3.9 GB (the shortest pit length 3T=0.44 .mu.m) although the jitter value is 13% if the line density is 4.7 GB (the shortest pit length 3T=0.40 .mu.m). Therefore, even if the prepit width W.sub.2 is smaller than the groove width W.sub.1, the jitter value can be made smaller than or equal to 8% by suitably lowering the line density. Thus, in the following Table 2, there are shown results obtained by actually measuring the jitter values while changing the line density (the shortest pit length 3T) variously, with respect to a DVD in which the prepit width W.sub.2 is set to 0.25 .mu.m, which is identical to the groove width W.sub.1. Hereupon, each of the prepits, whose prepit width W.sub.2 was smaller, was formed by making the cone angle of the prepit smaller using AZ as a developer. According to the measured results shown in Table 2, it may be understood that if the prepit width W.sub.2 is constant, the smaller the line density (the shortest pit length 3T) becomes, the smaller the jitter value becomes.
TABLE 2
Measured Jitter Values (Line Density Changed)
Shortest Pit Length 3T Measured Jitter
0.40 .mu.m 8.0%
0.44 .mu.m 7.2%
0.48 .mu.m 6.5%
0.60 .mu.m 5.3%
Meanwhile, in the following Table 3, there are shown results of the reproducing tests performed for DVDs provided with prepits according to the present invention (Embodiments 1 to 3) and DVDs with prepits which do not belong to the present invention (Comparisons 1 to 2), using a DVD player and a DVD-ROM drive on the market.
TABLE 3
Results of Reproducing Test for DVD
DVD DVD-ROM DVD-ROM
Player 1 Drive 1 Drive 2
Embodiment 1 .largecircle. .largecircle. .largecircle.
Enbodiment 2 .largecircle. .largecircle. .largecircle.
Embodiment 3 .largecircle. .largecircle. .largecircle.
Comparison 1 X X X
Comparison 2 X X X
(Notice)
.largecircle.: Good Reproducing Action
X : Action Malfunction Caused
Hereupon, the disk specification of each of the DVDs used in the above-mentioned reproducing tests is as follows.
(1) Emb. 1 3T = 0.40 .mu.m Jitter 8.0% Prepit Width 0.25 .mu.m
(2) Emb. 2 3T = 0.44 .mu.m Jitter 7.2% Prepit Width 0.25 .mu.m
(3) Emb. 3 3T = 0.60 .mu.m Jitter 5.3% Prepit Width 0.25 .mu.m
(4) Com. 1 3T = 0.40 .mu.m Jitter 13.0% Prepit Width 0.18 .mu.m
(5) Com. 2 3T = 0.40 .mu.m Jitter 12.0% Prepit Width 0.40 .mu.m
As apparent from Table 3, in each of the DVDs of Embodiments 1 to 3 according to the present invention, a good reproducing action is obtained, regardless of which reproducing apparatus is used. On the other hand, in each of Comparisons 1 and 2 to which the present invention is not applied, an action malfunction is caused, regardless of which reproducing apparatus is used. As described above, in the substrate 10, the depths of the groove 8 and the prepits 9 are identical to each other although their widths are different from each other. The reason is to make the production of the substrate (stamper) easier. That is, in general, the substrate 10 is produced using a stamper by means of injection molding, compression molding, 2P method or the like. Hereupon, for example, the stamper 10 is generally produced by means of a process utilizing a photolithography technique as shown in FIGS. 4A to 4F. In this case, if the depth of the groove 8 of the prepit 9 is constant, the stamper may be produced by a single photolithography operation so that the producing step may be simplified, thereby the producing cost of the stamper or substrate, and further the DVD may be reduced. Hereupon, the producing process of the stamper or substrate 10 utilizing the photolithography technique is roughly as follows. That is, as shown in FIG. 4A, at first, there is prepared a glass substrate 11 having a thickness of about 5 to 6 mm whose spreading surface has been polished. Then, as shown in FIG. 4B, a photo resist 12 of positive type is applied to the spreading surface of the glass substrate 11. Following that, as shown in FIG. 4C, onto the photo resist 12, laser rays 13 are applied with a pattern corresponding to the shapes of the groove 8 and the prepits 9 which are to be formed on the substrate (patterning exposure is performed). In consequence, a portion 12a of the photo resist 12, to which the laser rays 13 have been applied, becomes a material which can be dissolved into a developer (for example, alkali solution) by a photochemical reaction. Next, as shown in FIG. 4D, the photo resist 12 is subjected to a developing treatment using the developer (not shown) so that the portion 12a, which can be dissolved into the developer, is removed. Following that, as shown in FIG. 4E, a stamper 14 is produced, by performing nickel plating onto the glass substrate 11 and the photo resist 12. Although the photo resist is positive type one in this case, it is of course that a photo resist of negative type may be used. Meanwhile, it may be used such a process that after a mother die is produced from the stamper 14, another stamper for producing the substrate is produced from the mother die. After that, as shown in FIG. 4F, the substrate 10 having the groove 8 and the prepits 9 is produced using the stamper 14, by means of injection molding, compression molding, 2P method or the like. Hereupon, a transparent plastic material (for example, polycarbonate resin or the like) is used as the material of the substrate 10. In this case, the depths of the groove 8 and the prepits 9 become identical to the thickness of the photo resist 12. In consequence, if it is intended that the depths of the groove 8 and the prepits 9 are different from each other, the steps shown in FIGS. 4B to 4D must be repeated again using another photo resist having a different thickness after the developing treatment shown in FIG. 4D. Thereby, the process for producing the stamper 14 may be extremely complicated. As shown in FIGS. 5A and 5C, a recording layer 15 and a reflecting layer 16 are formed, by turns, on the whole spreading surface of the substrate 10 produced as described above. Therefore, the recording layer 15 and the reflecting layer 16 are also formed in the groove 8 and prepits 9 whose depths are identically d.sub.1. Further, a covering plate (not shown) is attached onto the reflecting layer 16 so that the write-once DVD 1 is completed. Hereupon, the recording layer 15 is composed of a pigment deposition film of a thin film type which has been formed by vapor-depositing an organic pigment (for example, organic pigment of porphyrin type, organic pigment of azo type) onto the spreading surface of the substrate 10. The pigment deposition film is formed, for example, by means of such a process that the organic pigment is heated and vaporized (sublimated) in a vacuum operation chamber under a lower pressure (for example, lower than or equal to 10.sup.-3 Torr), and then the vaporized pigment is cooled and solidified (vapor-deposited) on the spreading surface of the substrate 10. Meanwhile, the reflecting layer 16 is formed by vapor-depositing a metal with a higher reflection factor (for example, gold, silver, aluminum or the like) onto the recording layer 15 using a conventional metal deposition apparatus. Hereupon, the recording layer 15 may be composed of a pigment recording film which has been formed by means of a coating process such as spin coating process or the like. Hereinafter, the conformity (matching property) of the reproducing property of the optical disk with prepits will be described. In particular, it will be described as to such a case that each of the prepits 9 is composed of embossment formed on the substrate 10. If information has been written into the DVD 1 by applying laser rays thereto using a DVD drive (DVD recorder), the optical property (for example, light transmitting factor) of a predetermined portion of the recording layer 15 in the groove 8 is changed (for example, refraction factor of the pigment is reduced by recording operation) so that the portion becomes the recorded layer 17 due to the phase change in the recording pits, as shown in FIG. 5B. Thus, the digital information is recorded in the DVD 1. That is, as for the groove 8, the information is recorded in the form of a group composed of many recorded layers 17 each of which has been formed on the basis of the change of the optical property of the recording layer 15. On the other hand, in the case of the prepits 9, which differs from the case of the groove 8, the information is recorded in the form of pits, for example, as same as the case of a read-only CD (CD-ROM). That is, the information is recorded by means of patterns of the presence or shape of the prepits 9, on the basis of the phase difference due to the optical path length difference between the portion with prepits 9 and the portion without the prepits. Therefore, as for the prepits 9, the information has been recorded (stored) already at the time point that the DVD 1 is produced. That is, the prepits 9 are formed in the form corresponding to the information which is to be recorded into the prepit section, consequently the information is peculiar to the DVD 1. Hereupon, as shown in FIG. 5C, the intensity of the signal detected at the prepit 9, namely the signal detecting precision becomes higher, as the distance V.sub.1 (hereinafter, referred to "reflection surface interval") in the depth-wise direction of the prepits between the reflecting surfaces of the prepits 9 (interface between the pigment and the reflecting layer) and the reflecting surface of the portion without the prepits 9 (land portion) becomes larger. As described above, because the recording layer 15 of the DVD 1 is composed of the pigment deposition film of thin film type which has been formed by vapor-depositing the organic pigment onto the surface of the substrate, the reflection surface interval V.sub.1 becomes larger. Therefore the intensity of the signal, which is detected at the prepits 9, becomes stronger, consequently the signal detecting precision is raised. On the other hand, as shown in FIGS. 6A and 6C, if the recording layer 15 is formed by applying the organic pigment onto the surface of the substrate (for example, performing spin coating), most parts of the groove 8 and the prepits 9 are buried with the recording layer 15 (organic pigment). In this case, as shown in FIG. 6B, any particular disadvantage does not occur as to the groove 8, because the recorded layer 17 can be formed without hindrance. However, as apparent from FIG. 6C, the reflecting surface interval V.sub.2 becomes much smaller as for the prepits 9. Therefore the intensity of the signal detected at the prepits 9 becomes weaker so that the signal detecting precision may be lowered. Hereupon, as shown in FIG. 6D, if the depth d.sub.2 of the prepit 9 is made larger, the reflecting surface interval V.sub.3 may become comparatively larger so that the signal detecting precision at the prepit 9 would be raised. However, in this case, there may occur such a disadvantage that the process for producing the stamper, which is used to produce the substrate 10, is complicated, as described above. Hereupon, a preferable depth d of the prepit is such a value in the range defined by the following expression 2. .lambda./(4n).gtoreq.d.gtoreq..lambda./(12n) Expression 2 d: preferable depth of the prepit .lambda.: wave length of the reproduced signal n: refraction factor of the substrate Meanwhile, when information is recorded in a non-recorded DVD 1 using a DVD recorder (DVD drive), or the information recorded in the recorded DVD 1 is reproduced using a DVD player (DVD drive), a tracking error signal (hereinafter, referred to "TE signal") is detected, while the optical pickup (objective lens) is controlled in the tracking direction by servo control, on the basis of the TE signal. However, in the case of the DVD 1 according to the present invention, the intensity or amplitude of the TE signal detected during the recording or reproducing operation differs from that of the prepit 9. FIG. 7 shows a changing characteristic with lapse of time of the intensity or amplitude of the TE signal, for example, when information recorded in the recorded DVD 1 is reproduced. In the reproducing operation, the TE signal is detected at the groove 8 in the test area 3 (or the lead-in area 4) before the time point of t.sub.1, detected at the prepits 9 in the lead-in area 4 during the period from t.sub.1 to t.sub.2, and detected at the groove 8 in the data region 5 after the time point of t.sub.2. As apparent from FIG. 7, the amplitude of the TE signal at prepits 9 (t.sub.1 to t.sub.2) is considerably smaller in comparison with the amplitude of the TE signal at the groove 8 (before t.sub.1, or after t.sub.2) Therefore, it is preferable that the amplitude of the TE signal of each of the groove 8 and the prepits 9 is adjusted in accordance with the properties of the TE signals. Moreover, FIG. 8 shows the magnitude of the amplitude of the TE signal of each of the groove 8 and prepits 9 in the DVD 1 according to the present invention, and a conventional read-only DVD (DVD-ROM). Hereupon, in the graph as to the groove 8 of the DVD 1 according to the present invention shown in FIG. 8, the solid line indicates the amplitude in the non-recorded condition (recording) while the broken line indicates the amplitude in the recorded condition (reproducing). As apparent from FIG. 8, as for the groove 8 of the DVD 1, the amplitude of the TE signal detected when the information is recorded in the non-recorded DVD 1 (solid line) is about 1/2 of the amplitude of the TE signal detected when the information in the recorded DVD 1 is reproduced. Therefore, in order to cope with the above-mentioned amplitude differences, a push-pull tracking control is performed during the recording operation while a phase difference tracking control is performed during the reproducing operation. On the other hand, as for the prepits 9, the amplitude of the TE signal is constant, regardless of whether the DVD is non-recorded or recorded. Therefore, the prepits 9 must be able to produce TE signal having the amplitude, which can cope with the both tracking controls described above. Thus, in the DVD 1, the amplitude of the TE signal at the prepits 9 is set to a just middle value between the amplitude of the TE signal at the groove 8 of the non-recorded DVD 1 and the amplitude of the TE signal at the groove 8 of the recorded DVD 1 so as to be able to cope with the both tracking controls described above. Further, when the information is recorded into the non-recorded DVD 1, or when the information recorded in the recorded DVD 1 is reproduced, there is performed a focus control, namely a servo control of the optical pickup in the focus direction, on the basis of the reflection factor of the laser rays at the reflecting surface. Hereupon, in the above-mentioned focus control, it is preferable that the reflection factor at the reflecting surface is constant as much as it can. However, the reflecting surfaces of the groove 8 and the prepits 9 have different reflection factors from each other. But the reflection factor of the groove 8 is not related to whether the DVD 1 is non-recorded or recorded (identical for the both). FIG. 9 shows a changing characteristic with lapse of time of the reflection factor of the laser rays at the reflecting surface, for example, when the information recorded in the recorded DVD 1 is reproduced. In the reproducing operation, the information of the prepits 9 in the lead-in area 4 is reproduced before the time point of t.sub.3, while the information of the groove 8 in the data area 5 is reproduced after the time point of t.sub.3. As apparent from FIG. 9, the reflection factor at the prepits 9 (before t.sub.3) is considerably higher than the reflection factor at the groove 8 (after t.sub.3). Therefore, in the case that the DVD 1 according to the present invention is used, it is preferable that there is produced a condition which is equivalent to the condition that the reflection factor is lowered to a standard value i.sub.0 by lowering the circuit gain of the focus control system when the information is reproduced or recorded at prepits 9, while there is produced a condition which is equivalent to the condition that the reflection factor is raised to the standard value i.sub.0 by increasing the circuit gain when the information is reproduced or recorded at groove 8, so as to obtain an effect as same as of the case that the reflection factor of the groove 8 is identical to that of the prepits 9. Because the depth of the prepit 9 in the DVD 1 is smaller than that of a conventional normal pit, the modulation factor (ratio of the longest signal 14T to the reflection factor) of the data signal (prepit signal) at the prepit section is lowered to about 30 to 40% in comparison with that of the data signal at the data area 5 (groove 8). Therefore, it is preferable to lower the recording density (line recording density, track density) in the prepit section, in order to improve the quality of the signal at the prepit section. In the case that the depths of the groove 8 and the prepits 9 are, for example, identically 50 nm, the jitter values of the prepit signals at the density of 4.7 GB (track pitch being 0.74 .mu.m, the shortest pit length being 0.4 .mu.m) and at the density of 3.9 GB (track pitch being 0.8 .mu.m, the shortest pit length being 0.44 .mu.m) are as follows. 3.9 GB . . . prepit jitter value: 8% 4.7 GB . . . prepit jitter value: 13% As described above, if the modulation factor is about 30%, a good signal quality can be obtained by lowering the recording density in the prepit section. Further, it is preferable that every prepit section is alternately formed on the track, in the radial direction of the disk. Meanwhile, it is preferable to boost the prepit signal of electric signal state so as to improve the modulation factor. That is, it is preferable to lower the shortest recording frequency by changing the modulation rule so as to improve the signal quality (C/N). Meanwhile, the prepits 9 in the DVD 1 may be formed by locally expanding the groove 8 (making the groove width wider). That is, in order to smoothly connect the prepit section to the groove 8 in the data area 5 following the prepit section, it is necessary to provide a dummy groove area before the groove 8 in the data area 5. Hereupon, if any prepits 9 do not exist, there may occur such a disadvantage that the phase difference tracking can not be performed when the dummy groove area is reproduced using a reproducing player. However, the above-mentioned disadvantage can be solved by locally expanding the dummy groove area to form dummy pits. In the write-once DVD 1 according to the present invention, the prepit section (prepits 9) have previously stored copy managing key information and disk type identifying information. Thus, when information in another DVD is to be copied to the DVD 1, it may be possible to prevent copying of the information on the basis of the information recorded in the prepit section if a predetermined condition to allow copying the information is not satisfied. Therefore, it may become possible to physically prevent the information recorded in a source disk such as a read-only DVD or the like from being copied without a just reason, by propagating the above-mentioned write-once DVD 1 and by applying any regulation for using of a conventional write-once (writable) DVD. Accordingly, the copyright as to the information recorded in the source disk can be effectively protected. Further, the disk information can be sufficiently managed when the information is read or written. That is, it may become possible to construct a system for sufficiently managing the disk information. Hereinafter, there will be described a concrete structure of the DVD recorder (DVD drive), which can copy or record the information recorded in the source disk as a requisite information into the DVD 1 according to the present invention while preventing the copyright from being infringed. As shown in FIG. 10, the DVD recorder 20 is provided with a source disk holding section 21 for holding a source disk such as a read-only DVD 18 (DVD-ROM) or a conventional recorded write-once DVD 19 (DVD-R) etc., and a copying section 22 which can fundamentally copy (record) the information in the source disk, which is held in the source disk holding section 21, into a non-recorded write-once DVD 1. Further, the DVD recorder 20 is also provided with a copy managing section 23 which can allow or inhibit a copying operation of the copying section 22, and a conformity condition information storing section 24 for storing information (conformity condition information) relating to various conditions for allowing to copy the information into the DVD 1. Hereupon, the conformity condition information is inputted to the conformity condition information storing section 24 through a telecommunication line or a potable recording medium, although it is not shown in detail. In the DVD recorder 20, the copy management key information (key information for preventing copying), which is recorded (stored) at the prepit section (prepits 9) in the non-recorded DVD 1 held within the copying section 22, is read by a copy management key information reading section 25, and then the copy management key information is sent to a conformity judging section 26. Then information to be copied (hereinafter, referred to "copy information") such as document, image, video, voice, sound or the like, which is recorded in the source disk within the source disk holding section 21, is read by the copy information reading section 27, and then the copy information is sent to the copy managing section 23. Meanwhile, the copyright information, which is recorded in the source disk, is read by the copyright information reading section 28, and then the copyright information is sent to the conformity judging section 26. Moreover, the conformity condition information, which is stored in the conformity condition information storing section 24, is read by a conformity condition information reading section 29, and then the conformity condition information is sent to the conformity judging section 26. Thus, in the conformity judging section 26, it is judged whether the copy management key information and the copyright information satisfy the conformity condition stored in the conformity condition information storing section 24 or not, namely whether copying the information recorded in the source disk to the DVD 1 satisfies a predetermined condition for allowing the copy or not, and then the resulting judgement is sent to the copy managing section 23. On that occasion, the conformity judging section 26 also sends the copyright information of the source disk, or information formed by combining (hybridizing) the copyright information with the information held in the prepit section, to the copy managing section 23. Thus, for the copying section 22, the copy managing section 23 allows or inhibits to copy the copy information into the DVD 1, on the basis of the above-mentioned resulting judgement which has been sent thereto from the conformity judging section 26. To be concrete, if the copy management key information and the copyright information satisfy the conformity condition, namely if the copying operation does not correspond to an unjust action with a infringement of the copyright or the like so as to be permitted without questions, the copy information and the copyright information are sent from the copy managing section 23 to the copying section 22, and then the copy information and the copyright information are written into the DVD 1 by the copying section 22. On the other hand, if the copy management key information and the copyright information do not satisfy the conformity condition, namely if the copying operation is an unjust action with a infringement of the copyright or the like, the copy information is not sent from the copy managing section 23 to the copying section 22 so that the copy information cannot be copied in the copying section 22. That is, in the DVD recorder 20, it is physically impossible to copy the information in the source disk to the DVD 1, if the copy management key information in the DVD and the copyright information in the source disk do not satisfy the conformity condition. Therefore, if the above-mentioned conformity condition is preferably set to such that the condition is satisfied only when the information of the source disk is permitted to be copied into the DVD 1, the information recorded in the source disk can be physically prevented from being copied to the DVD 1 without a just reason so that the copyright as to the information recorded in the source disk can be effectively protected. Hereinafter, there will be described a concrete structure of a DVD player (DVD drive), which can reproduce the information recorded in the source disk such as the read-only DVD 18 or the recorded DVD 1 into which is information has been written by the above-mentioned DVD recorder 20, while effectively preventing the copyright from being infringed. As shown in FIG. 11, the DVD player 30 is provided with a reproducing section 31 which can reproduce the information recorded in the disk to be reproduced (hereinafter, referred to "reproduction disk") such as the read-only DVD 18 or the recorded DVD 1 etc., and a reproduction managing section 32 which can allow or inhibit an information reproducing operation for the reproducing section 31. Further, the DVD player 30 is provided with a conformity condition information storing section 33 for storing information (conformity condition information) relating to various conditions for allowing to reproduce the information of the reproduction disk. In the DVD player 30, it is judged whether the reproduction disk held in the reproducing section 31 is the recorded DVD 1 or the read-only DVD 18 (or other conventional DVDs). Thus, if the reproduction disk has been judged as the read-only DVD 18, the resulting judgement is sent to the reproduction managing section 32. In this case, for the reproducing section 31, the reproduction managing section 32 allows the reproduction of the information if key information for inhibiting a reproducing operation for the read-only DVD 18 is not contained, while the section inhibits the reproduction of the information if the key information for inhibiting the reproducing operation is contained. That is, as for the DVD player 30, information recorded in the read-only DVD 18 or other normal DVDs can be reproduced approximately as same as the case of a conventional DVD player. On the other hand, if the reproduction disk has been judged as is the recorded DVD 1 by a disk type judging section 34, the resulting judgement is sent to a conformity information reading section 35. In this case, the conformity information reading section 35 reads copy management key information and copyright information recorded in the DVD 1 within the reproducing section 31, and then sends the information to a conformity judging section 36. Meanwhile, conformity condition information stored in the conformity condition information storing section 33 is read by a conformity condition information reading section 37, and then the conformity condition information is sent to the conformity judging section 36. Thus, in the conformity judging section 36, it is judged whether the copy management key information and the copyright information satisfy the conformity condition or not, namely whether the information recorded in the DVD 1 satisfies a predetermined condition for allowing the reproduction or not, that is whether the information is not recorded by an unjust action with an infringement of the copyright, and then the resulting judgement is sent to the reproduction managing section 32. Thus, for the reproducing section 31, the reproduction managing section 32 allows or inhibits to reproduce the information of the DVD 1, on the basis of the above-mentioned resulting judgement which has been sent thereto from the conformity judging section 36. Hereupon, if the copy management key information and the copyright information satisfy the conformity condition, namely if the information to be reproduced has been recorded by a just process, reproduction of the information of the DVD 1 in the reproducing section 31 is permitted so that the information of the DVD 1 is reproduced. On the other hand, if the copy management key information and the copyright information do not satisfy the conformity condition, namely if the information to be reproduced has been recorded by an unjust process, reproduction of the information of the DVD 1 in the reproducing section 31 is inhibited. As described above, when the. information in the recorded DVD 1 is reproduced by the DVD player 30, reproducing the recorded information is inhibited if the copy management key information and the copyright information do not satisfy the conformity condition. Therefore, if by any chance the information, which has been inhibited from being copied, is copied to the DVD 1 by mistake, it is physically impossible to reproduce the recorded information. In consequence, the copyright as to the information recorded in the source disk can be strongly protected. Hereupon, it is of course that the above-mentioned DVD recorder 20 and DVD player 30 may be integrally constructed so as to form a DVD recorder/player. In the DVD 1, DVD recorder 20 or DVD player 30, the frequency for reading the signal at the prepit section (prepits 9) may be different from the frequency for reading the signal at the groove 8. Meanwhile, the modulation rules for the signals recorded in the prepit section (prepits 9) and the groove may different from each other. Hereupon, it is desirable that the prepit section can be read with lower frequency during the reproducing operation, in comparison with the other. The DVD player 30 obtains the information by turns from the groove portion, the pit portion and the groove portion. Further, in the DVD recorder 20 or the DVD player 30, the conformity condition may be stored together with the conformity information in the prepit section. Further, for example, in a DVD or the like into which a commercial message is recorded, it may be possible such a matter that a specified sponsor buys the copyright, and then the sponsor permit the copy of the information in compensation for recording the commercial message into the DVD. INDUSTRIAL APPLICABILITY As described above, each of the optical disk and the optical disk drive according to the present invention is useful as an optical storage medium which can prevent the information recorded in the optical disk from being unjustly copied or reproduced, and is particularly suitable for using as a DVD or a driving apparatus thereof, or a CD or a driving apparatus thereof.
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