JPH11296864A - Optical disk recorder, optical disk recording method, optical disk, optical disk reproducing device, and optical disk reproducing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make an illegal copy effectively avoidable by applying to an optical disk recording e.g. a high tone quality digital audio signal, its optical disk forming device, a reproducing device related to an optical disk recorder, concerning an optical disk recording method, an optical disk, an optical disk reproducing device and an optical disk reproducing method. SOLUTION: A sub-data line is formed by the key data DK required for decoding a main data line D1 and the data SID specifying a processing form of decoding, and this sub-data line is recorded by locally changing a width of a pit, etc., at the timing not affecting positional information of an edge detected at a reproducing time. Further, related to the data recording by longitudinal directional modulation of a mark and a space, the key data of the data are recorded by the latitudinal directional modulation of the mark or the space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording apparatus, an optical disk recording method, an optical disk, an optical disk reproducing apparatus, and an optical disk reproducing method, for example, an optical disk for recording a high-quality digital audio signal, and an apparatus for producing the optical disk. Can be applied to a playback device. According to the present invention, a sub data sequence is created by using key data necessary for decryption of a main data sequence and identification data for specifying a decryption processing mode, and does not affect position information of an edge detected during reproduction. By recording the secondary data string by changing the width of the mark or space locally at the timing, illegal copying can be effectively avoided.

According to the present invention, illegal copying can be effectively avoided by recording key data of data to be recorded by modulation in the length direction of the mark or space by modulation in the width direction of the mark or space. To do.

[0003]

2. Description of the Related Art Conventionally, for example, in a compact disc made of such an optical information recording medium, after audio data is processed, EFM (Eight-to-Fourteen Modular) is performed.
lation) By modulation, a pit string having a period of 3T to 11T is formed with respect to a predetermined basic period T, whereby audio data and the like are recorded.

A compact disk player for reproducing this compact disk irradiates the compact disk with a laser beam and receives return light to obtain a reproduced signal whose signal level changes in accordance with the amount of the return light. The reproduction signal is binarized at a predetermined slice level to generate a binarized signal. Further, the PLL circuit is driven from the binarized signal to generate a reproduction clock, and the binarized signal is sequentially latched by the reproduction clock. Generate reproduction data that changes at 11T.

[0005] The compact disk player decodes the reproduced data generated in this way by data processing corresponding to data processing at the time of recording, and reproduces audio data and the like recorded on the compact disk.

In a transmission system for transmitting audio data or the like via an optical information recording medium as described above,
In order to effectively avoid illegal copying, for example, a copy protection system as shown in FIG. 18 or FIG. 19 has been proposed.

[0008] That is, in the copy protection system 1 shown in FIG. 18, the data D 1 to be recorded is scrambled by the master key KM in the encoder 3 of the disc production side 2, and the scrambled data is recorded on the optical disc 5. Further, in the decoder 7 of the reproducing apparatus 6, the reproduced data reproduced from the optical disk 5 is descrambled by, for example, a master key KM common to the disc producing side, and the descrambled data is converted to an MP.
Processing is performed by a decoder 8 such as an EG. Thus, the copy protection system 1 encrypts the data D1 using the common master key KM with the reproduction side determined in advance, thereby preventing illegal copying.

A copy protection system 10 shown in FIG.
Encrypts the data D1 with the master key KM, the disc key KD unique to the optical disc 11, and the title key KT unique to each work. That is, the disc production side 12
In the encoder 13, the disc key KD is scrambled by the master key KM, and the scrambled disc key KD is recorded on the optical disc 11. In the encoder 14, the title key KT is scrambled by the scrambled disk key KD, and the scrambled title KT
Is recorded on the optical disc 11.

Further, the disc producing side 12 scrambles the data D 1 to be recorded by the scrambled title KT in the encoder 15 and records it on the optical disc 11. This allows the disc production side 12
Records the data D1 on the optical disc 11 by multiplex scrambling the data D1 based on the master key KM.

[0010] On the other hand, the reproducing device 16 is provided with the decoder 1.
In step 7, the scrambled disk key KD is descrambled by the master key KM to decrypt the disk key KD. Further, in the decoder 18,
The scrambled title key KT is descrambled by the disc key KD, and the subsequent decoder 19 descrambles the data D1 by the disc key KD.

As a result, the copy protection system 10
Is designed to prevent illegal copying by taking into account the creator of the disc and the creator of the work.

[0012]

There are two types of illegal copying. One is a method of decrypting a master key or the like, and producing an optical disk that can be reproduced by a reproducing apparatus even if it is a pirate disc, based on the decryption result. The remaining one is a method of physically copying the pit shape formed on a regular optical disk.

In a copy protection system using a master key or the like, the former illegal act can be dealt with by making it difficult to decipher the master key or the like. There is a disadvantage that the board cannot be excluded. Further, there is a disadvantage that the latter illegal copy cannot be handled at all.

The present invention has been made in view of the above points, and proposes an optical disk recording apparatus, an optical disk recording method, an optical disk, an optical disk reproducing apparatus, and an optical disk reproducing method capable of effectively avoiding illegal copying. What you want to do.

[0015]

According to the first or eighth aspect of the present invention, there is provided an optical disk recording apparatus or an optical disk recording method, wherein position information of an edge of a mark detected at the time of reproduction is used. At a timing that does not affect, the width of the mark or space is locally changed to record a sub data row, and this sub data row is at least key data and the main data row using the key data. It is composed of identification data for specifying a processing mode for decryption.

In the invention according to the fifteenth aspect, in the optical disc, the width of the mark or the space is locally changed at a timing that does not affect the position information of the edge of the mark detected at the time of reproduction. A column is recorded, and this sub data column is composed of at least key data and
The identification data specifies the processing mode for decrypting the main data string using the key data.

According to the twenty-fifth aspect of the present invention, in the optical disc reproducing apparatus, a processing mode for decrypting the main data string by the identification data assigned to the sub data string is set, and The key data sequence is decrypted using the assigned key data, and the signal level of the reproduced signal is set at a timing which is separated from the timing at which the reproduced signal crosses the average level by a predetermined time with respect to the clock. Is detected, the result of the signal level detection is determined, and the sub data sequence is reproduced.

According to a thirtieth aspect of the present invention, in the optical disk reproducing method, the main data sequence recorded by the length of the mark and the space is encrypted by a predetermined decryption using a predetermined key data. And the secondary data sequence recorded by the change in the local width of the mark is reproduced to detect the key data and the decryption processing mode.

Further, in the invention according to claim 35, in the optical disk recording apparatus, an encryption means for encrypting main data using key data to generate encrypted data, and a mark according to the encrypted data. And a main modulating means for modulating the space in the length direction and a sub-modulating means for modulating the width of the mark or the space according to the key data.

In the invention according to claim 38, in the recording method for an optical disk, main data is encrypted using predetermined key data to generate encrypted data, and a mark and a mark are generated in accordance with the encrypted data. The space is modulated in the length direction, and the width of the mark or space is modulated according to the key data.

In the invention according to claim 39, in the optical disk, data encrypted by using predetermined key data by modulation of marks and spaces in the length direction is recorded in the program area, and the lead-in is performed. Key data is recorded in the area by modulation of the mark or space in the width direction.

Also, in the invention according to claim 43, in the optical disk reproducing apparatus, in the program area of the optical disk, data encrypted using predetermined key data by modulation of marks and spaces in the length direction is used. In the lead-in area, when key data for decrypting data encrypted by modulation in the width direction of the mark or space is recorded in the lead-in area, the mark or space width direction is shifted from the lead-in area. Key data reproducing means for detecting a change in the key data and reproducing key data, and decryption means for decrypting data recorded in the program area based on the key data reproduced by the key data reproducing means. Be prepared.

According to a forty-fourth aspect of the present invention, in the method for reproducing an optical disk, in the optical disk, in a program area, data encrypted by using predetermined key data by modulating marks and spaces in a length direction. Is recorded, and in the lead-in area, when key data for decrypting data encrypted by modulation in the width direction of the mark or space is recorded, the width of the mark or space is larger than that of the lead-in area. The key data is reproduced by detecting a change in the direction, and the data recorded in the program area is decrypted based on the key data.

According to the first or eighth aspect of the present invention, in the optical disk recording apparatus or the optical disk recording method, the mark or the space of the mark or space is detected at a timing that does not affect the position information of the edge of the mark detected at the time of reproduction. If the width of the sub-data string is locally changed and the sub-data row is recorded, the sub-data row can be recorded physically difficult to copy and difficult to analyze depending on the degree of the change. Furthermore, if this sub data string is composed of at least key data and identification data for specifying a processing mode for decrypting the main data string using the key data, the sub data string can be detected. Even if the processing form specified by the identification data can be kept confidential, illegal copying can be effectively avoided.

According to the structure of the fifteenth aspect, in the optical disc, the width of the mark or the space is locally changed at a timing that does not affect the position information of the edge of the mark detected at the time of reproduction. If a data string is recorded, it will be physically difficult to copy depending on the degree of this change,
In addition, it is possible to record a sub-data string in a case where analysis is difficult.
Further, if the secondary data string is composed of at least key data and identification data for specifying a processing mode for decrypting the main data string using the key data, the secondary data string can be detected. Even if the processing form specified by the identification data can be kept confidential, illegal copying can be effectively avoided.

According to a twenty-fifth aspect of the present invention, in the optical disc reproducing apparatus, a processing mode for decrypting the main data string by the identification data allocated to the sub data string is set, If the main data string is decrypted using the key data assigned to, the processing form specified by the identification data can be kept confidential even when the sub data string is detected . This makes it difficult to detect if the signal level of the reproduced signal is detected at a timing separated by a predetermined time from the timing at which the reproduced signal crosses the average value level, and the signal level detection result is determined to reproduce the sub data sequence. The sub-data recorded by changing the pit width or the like can be detected, and the encryption can be released.

According to a thirty-fourth aspect of the present invention, in the method for reproducing an optical disk, the main data sequence recorded by the length of the mark and the space is encrypted by using a predetermined key data. If the key data and the decryption processing mode are detected by reproducing the sub data sequence recorded by the change in the local width of the mark and detecting the processing mode of decryption, the Can be reproduced to decrypt the main data string.

According to a thirty-fifth aspect of the present invention, in the optical disk recording apparatus, an encryption means for encrypting main data using key data to generate encrypted data;
According to the encrypted data, the main modulating means for modulating the mark and the space in the length direction, and according to the key data,
By providing a sub-modulation means for modulating the width of a mark or a space, key data can be recorded physically difficult to copy and difficult to analyze, thereby effectively preventing illegal copying. Can be avoided.

According to a thirty-eighth aspect of the present invention, in the optical disk recording method, the main data is encrypted using predetermined key data to generate encrypted data, and the mark data is written in accordance with the encrypted data. If the width of the mark or space is modulated in accordance with the key data and the width of the mark or space, the key data can be physically recorded in a manner that is difficult to copy and analyze. Thus, illegal copying can be effectively avoided.

According to a thirty-ninth aspect of the present invention, in the optical disc, data encrypted by using predetermined key data by modulation of marks and spaces in the length direction is recorded in the program area. In the in-area, the key data is recorded by modulation in the width direction of the mark or space, so that in the key data, it is physically difficult to copy, and it is possible to record the data in a manner that is difficult to analyze. Thus, illegal copying can be effectively avoided.

According to the structure of the present invention, in the optical disk reproducing apparatus, in the optical disk, in the program area, the data encrypted by using the predetermined key data by the modulation in the length direction of the mark and the space. Is recorded, and in the lead-in area, if key data for decrypting data encrypted by modulation in the width direction of the mark or space is recorded,
Key data reproducing means for detecting key or space width changes of the mark or space from the lead-in area and reproducing key data; and a key data reproducing means for reproducing data recorded in the program area based on the key data reproduced by the key data reproducing means. By providing decryption means for decrypting the data, it is possible to reproduce the key data which is physically difficult to copy and difficult to analyze by modulating the mark width, and is recorded in the program area from the key data. Data can be decrypted.

According to the structure of claim 44, in the reproducing method of the optical disk, the optical disk is encrypted using predetermined key data in the program area by modulation of marks and spaces in the length direction. When data is recorded and key data for decrypting data encrypted by modulation of the mark or space in the width direction of the mark or space is recorded in the lead-in area, the mark or space of the mark or space is read from the lead-in area. The key data is reproduced by detecting a change in the width direction, and based on this key data, if the data recorded in the program area is decrypted, it becomes physically difficult to copy due to the modulation of the mark width, and it is analyzed. Reproduces difficult recorded key data and decrypts the data recorded in the program area from this key data. It can be.

[0033]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(1) First Embodiment (1-1) Configuration of First Embodiment FIG. 1 is a block diagram showing an information transmission path of a copy protection system according to a first embodiment of the present invention. FIG. The copy protection system 111 includes a disc creator side 112,
It comprises an optical disk 119 and a playback device 124.

Here, the disc producing side 112 generates a digital audio signal D 1, which is main data to be recorded on the optical disc 119, from a predetermined data generator 114. Here, the data generator 114 is a reproducing device that reproduces original data recorded on, for example, a master tape or the like.

The disc producing side 112 generates a master key KM from the master key generator 115, and the digital audio signal D1 is encrypted by the scrambler 113 using the master key KM. Further, the disc producing side 112 records the encrypted digital audio signal D1 in the program area of the optical disc 119. The encryption of the digital audio signal D1 by the master key KM and the recording on the optical disk 119 are
Except that only one type of scrambler is provided for encryption processing, the configuration is the same as the configuration according to the second embodiment described later. Accordingly, the disc producing side 112 records the digital audio signal encrypted by the modulation of the pit length and the interval between the pits in the program area of the optical disc 119.

The disc production side 112 uses the pit width modulator 116 to transfer the master key KM to the optical disc 11.
9 is recorded in the lead-in area. Here, the disc producing side 111 records the master key KM in the lead-in area of the optical disc 119 by applying the second modulator 47 of FIG. 3 described later in the second embodiment.

That is, the master key KM is recorded in the lead-in area of the optical disk 119 by a local change in the pit width at a timing that does not affect the position information of the edge detected during reproduction. In addition, pits having a length equal to or longer than a predetermined length are recorded in the lead-in area of the optical disk 119 due to a local change in the pit width, and are then encrypted with random numbers and recorded on the optical disk 119. As a result, the disc producing side 112 records the master key KM on the optical disc 119 so that it is difficult to decode.

In response, the reproducing device 124 processes the reproduced signal obtained from the lead-in area, and restores the master key KM by the demodulator 120. Further, the playback device 124 processes the playback signal obtained from the program area and encrypts the digital audio signal D.
And demodulator 1 in the descrambler 122.
The decryption of this digital audio signal D1 is decrypted by the master key KM output by 20.

(1-2) Operation of First Embodiment In the above configuration, in the copy protection system 111, the digital audio signal D is transmitted by the master key KM.
1 is encrypted and recorded in the program area of the optical disk 119 by modulation of the pit length and the interval between pits, and the master key KM is recorded in the lead-in area of the optical disk 119 by modulation of the pit width.

The pit width is modulated by changing the pit width locally at a timing that does not affect the position information of the edge detected during reproduction. As a result, the digital audio signal D1, which is the main data, can be easily reproduced with the same configuration as that of the conventional reproducing apparatus although it is encrypted.

On the other hand, in the master key KM, since the information is recorded by the local change of the pit width, for example, the protective film of the optical disk 119 is peeled off, and the concave / convex shape of the disk substrate is transferred to a mold, and the stamper is moved. Even if it is attempted to manufacture an illegal optical disc (that is, an illegal copy in which the pit shape is physically copied), it is difficult to faithfully transfer the change in the pit width,
This makes it possible to effectively avoid this kind of piracy.

Also, in an illegal copy by a method of decrypting the master key KM, it is difficult to find out because the master key KM is recorded due to a local change in the pit width. Can also be effectively avoided.

Further, at this time, since the master key KM is recorded by being modulated by a random number, it is possible to make the decoding of the key data more difficult.

(1-3) Effects of the First Embodiment According to the above configuration, a digital audio signal encrypted by modulation of the pit length and the interval between pits is recorded.
By recording the encrypted key data by modulating the pits in the width direction, illegal copying can be effectively avoided.

(2) Second Embodiment (2-1) Configuration of Second Embodiment FIG. 2 is a block diagram showing an information transmission path of a copy protection system according to a second embodiment of the present invention. FIG. The information transmission path 20 according to the copy protection system has a point that the disc producing side 21 has a plurality of scramblers to be encrypted by different encryption methods, and one of the plurality of scramblers is designated by the scrambler identification data. The digital audio signal D1 is selectively used by a disk key.
In addition, the disc key and the scrambler identification data are encoded by modulating the pit width.
The configuration is the same as the configuration according to the above-described first embodiment except that the information is recorded in the first embodiment.

That is, the disc producing side 21 inputs the digital audio signal D1 to the selection circuit 23, and selectively supplies the digital audio signal D1 to the scramblers 25A to 25X designated by the scrambler identification data SID. These scramblers 25A to 25X
Are set so as to perform different encryption processing, respectively, and scramble the digital audio signal D1 using the same disk key DK and output the digital audio signal D1.

In this case, the scrambler identification data SID is used as the scrambler 25 for scramble processing.
This is identification data for selecting A to 25X. In this case, since the processing form is different in each of the scramblers 25A to 25X, it is also identification data for specifying the processing form of the scramble processing. The disc key DK is key data for scrambling. The scrambler identification data SID and the disc key DK are randomly generated by a disc creator and a disc maker, for example, for each optical disc 26 according to a predetermined selection criterion, together with an initial pointer PIV described later. Disc production side 21
Is a scrambler 25A formed by selectively scrambling the digital audio signal D1 in this manner.
The output data of .about.25X is recorded on the optical disk 26.

Further, on the disc producing side 21, the scrambler identification data SID and the disc key DK are recorded on the optical disc 26 so as to make it difficult to decipher. Here, the disc producing side 21 is configured to sequentially form a pit row on the optical disc 26, and determines a pit length and a pit interval in this pit row by a predetermined reference cycle in accordance with output data of the scramblers 25A to 25X. The digital audio signal D on the optical disc 26.
Record 1. The disc producing side 21 selects a pit having a predetermined length or more from the pit row formed in this way, and at a timing that does not affect the edge position information of each pit detected at the time of reproduction, this pit is not affected. By changing the pit width of the optical disk 2, the scrambler identification data SID and the disk key DK are hardly deciphered.
Record in 6.

In response to this, in the reproducing apparatus 27, the signal level of the reproduced signal is detected by the detecting section 28, and the scrambler identification data SID and the disk key DK are demodulated. Further, in a plurality of descramblers 29A to 29X corresponding to the disc producing side 21, the reproduced data is descrambled by the disc key DK.
Further, the selection circuit 30 uses the scrambler identification data S
The descramble results of the descramblers 29A to 29X specified by the ID are selected, and the
To reproduce the digital audio signal D1 recorded in.

FIG. 3 is a block diagram showing an optical disk recording device used for manufacturing the optical disk 26. An optical disk 26 according to this embodiment is prepared by developing an original disk 42 exposed by the optical disk recording device 40 and then performing electroforming to create a mother disk. Is created.

The master disc 42 is formed by, for example, applying a photosensitive agent to a flat glass substrate. The spindle motor 43 is controlled by a spindle servo circuit 44 to
The disk master 42 is driven to rotate. At this time, the spindle motor 43 outputs an FG signal FG whose signal level rises at every predetermined rotation angle by an FG signal generator provided at the bottom. The spindle servo circuit 44 drives the spindle motor 43 so that the frequency of the FG signal FG becomes a predetermined frequency, thereby rotating the disk master 42 under the condition of a constant linear velocity.

The recording laser 45 is constituted by a gas laser or the like, and emits a predetermined amount of laser beam L. The optical modulator 46 is configured by an electroacoustic optical element or the like, and emits a laser beam L incident from the recording laser 45 by performing on / off control according to the modulation signal S3 supplied from the second modulation circuit 47.

The mirror 48 bends the optical path of the laser beam L and emits it toward the master disc 42. The objective lens 49 converts the reflected light of the mirror 48 into the master disc 4.
Light is focused on the recording surface of No. 2. Mirror 48 and objective lens 4
Reference numeral 9 denotes a disk master 4 by a thread mechanism (not shown).
2 in order to move sequentially in the radial direction in synchronization with the rotation of the second rotation. Thus, in the optical disk recording device 40, the condensing position of the laser beam L is sequentially displaced in the outer peripheral direction of the disk master 42 to form a spiral track on the disk master 42. At this time, a pit row corresponding to the modulation signal S3 is formed on this track.

The scrambler 51 is composed of the scramblers (SC) 25A to 25X described above with reference to FIG.
Is scrambled and output. Here, this digital audio signal D1 is sampled at a sampling frequency of 2.8224 [MHz], which is 64 times the sampling frequency of 44.1 [kHz] of a normal digital audio signal, and then 1-bit quantized. This is a digital audio signal, which is supplied to the scramble unit 51 by serial data.

FIG. 4 is a block diagram showing the structure of the scrambler 25A. Here the scrambler 25A
A shift register 55 in which a predetermined number of serially connected latch circuits that operate on the basis of the channel clock CK;
An exclusive OR circuit 56 for outputting exclusive OR data D2 between the output data of the shift register 55 and the digital audio signal D1, and an exclusive OR circuit for the latch output of a predetermined stage of the shift register 55 An exclusive OR circuit 57 that feeds back to the first stage 55.

The scrambler 25A outputs the digital audio signal D1 from the initial stage of the shift register 55 for each sector formed by recording the digital audio signal D1 on the disk master 42.
By the stage, a disk key DK having a k-bit length is set, and the succeeding stage r (16 in this embodiment) is set.
In the (stage) stage, an initial value IV having an r-bit length is set.

On the other hand, other scramblers 25B-
25X is the same as the scrambler 25A except that the input stage of the exclusive OR circuit 57 is different in each of the scramblers 25A to 25X, and the initial value IV is different in each of the scramblers 25A to 25X. . The scramblers 25A to 25X are configured such that the input stage of the exclusive OR circuit 57 is connected to each of the scramblers 25A to 25X.
The difference in 5X sets the encryption processing mode to be different. With these, the scrambler 25A ~
The 25X scrambles the digital audio signal D1 with different processing modes based on the disc key DK and the initial value IV, and outputs the digital audio signal D1 with different logic levels.

Here, as shown in FIG. 5, the initial value IV is constituted by 16-bit numerical data specified by a 1-bit initial pointer PIV, and is set for each of the scramblers 25A to 25X. It has been done. This also allows Scrambler 25B
-25X is designed to ensure randomness among the scramblers 25B-25X. Further, the scramble processing result D3 based on a random logic level can be output even when a digital audio signal D1 having a continuous logic 0 is input by the initial value IV.

Thus, the scrambler 51 selectively uses the scramblers 25B to 25X specified by the scrambler identification data SID among the scramblers 25B to 25X that output different scramble processing results in this manner. Then, the digital audio signal D1 is scrambled.

The modulation circuit 52 includes a scrambler 51
After adding an error correction code to the output data D2 and the subcode data supplied from a subcode generator (not shown), an interleave process is performed. Further, by performing modulation according to a predetermined modulation method, modulated data D3 that repeats the rising and falling of the signal level in a range of 3T to 11T with one cycle T of the clock CK as a basic cycle is generated. Here, this period 3T is the shortest period in which the intersymbol interference in the pit row direction can be kept within a practically sufficient range in the optical system of the reproducing system. In the lead-in area of the optical disk 26, management data (TOC (Table Of Content) of the digital audio signal D1 supplied from a system control circuit (not shown) is provided.
s) Data) is similarly modulated and output.

Here, as shown in FIG.
Are synchronized with a predetermined channel clock CK (FIG. 6 (B)) and modulated data D3 (FIG. 6 (A-1) and (A-
2)) is generated. At this time, the modulation circuit 52 generates the modulation data D3 by inserting a frame sync at every predetermined cycle based on the channel clock CK, thereby forming the modulation data D3 with a frame structure in units of the sync frame. . Further, the modulation circuit 52 generates a frame clock FCK whose signal level rises for one clock cycle at the start timing of the frame sync (FIG. 6C). The optical disk recording device 40 processes the control data SC1 (FIG. 6D) by the disk key DK or the like in the second modulation circuit 47, which will be described later, based on the frame clock FCK.

The second modulation circuit 47 (FIG. 3)
The modulation data D3 output from 2 is modulated by the control data SC1, thereby generating a so-called double modulation signal S3.

FIG. 7 is a chart showing the control data SC1. The control data SC1 includes the disk key D
K, scrambler identification data SID, initial pointer PIV, error correction code CRC (Cyclic Redundancy)
Check) (16 bits), and these data are randomly arranged in accordance with a predetermined rule, and the data is made difficult to analyze.

The control data SC 1 is sequentially and cyclically supplied to the second modulation circuit 47 at a low transfer rate of one bit per frame based on the frame clock FCK during a period corresponding to the lead-in area of the optical disk 26. Is done. Conversely, the supply to the second modulation circuit 47 is controlled to be stopped during a period corresponding to the program area and the lead-out area of the optical disk 26.

FIG. 8 is a block diagram showing this second modulation circuit 47 in detail. In the second modulation circuit 47,
The synchronization detection circuit 61 detects a frame sync from the modulation data D3 and outputs a frame clock FCK.

As shown in FIG. 9, the PLL circuit 62 reproduces and outputs the channel clock CK from the modulated data D3 (FIG. 9A) (FIG. 9B).

The M-sequence generation circuit 63 is composed of a plurality of cascade-connected flip-flops and an exclusive OR circuit. After setting the initial values in the plurality of flip-flops with reference to the frame clock FCK,
The set contents are sequentially transferred in synchronization with the channel clock CK, and the M-sequence random number data MS in which logic 1 and logic 0 appear with equal probability by feedback between predetermined stages.
Generate The M-sequence signal MS thus generated is
The sequence is a pseudo-random number that repeats the same pattern at a cycle of one frame.

Exclusive OR circuit (XOR) 64
Receives the M-sequence signal MS and the control data SC1, and outputs the exclusive OR signal MS1 (FIG. 9D). That is, the exclusive OR circuit 64 outputs the control data SC
When 1 is logic 0, the exclusive OR signal MS1 is output according to the logic level of the M-sequence signal MS. Conversely, when the control data SC1 is logic 1, the logic level of the M-sequence signal MS is inverted. The exclusive OR signal MS1 is output.
As a result, the exclusive OR circuit 64 modulates the control data SC1 to which 1-bit data is allocated by the M-sequence random number during one frame period.

The flip-flop 65 stores the modulation data D3
The exclusive OR signal MS1 is latched at the timing of the rising edge (FIG. 9 (E)). Here, in this embodiment, the signal level of the modulation signal S3 is set to rise in response to the rising of the signal level of the modulation data D3, and the signal level of the modulation signal S3 is set to correspond to the rising period. Pits are formed on the disk master 42. Thus, the flip-flop 65 outputs the exclusive OR signal MS at the timing corresponding to the leading edge of each pit.
The logic level of 1 is sampled, and the sampling result is held until the timing corresponding to the leading edge of the following pit.

The delay circuit 66 includes the flip-flop 6
5 is delayed for a predetermined period, and the delayed signal M
The SHD is output (FIG. 9 (F)). Here, this delay period is a time required for the detection circuit 67 to perform processing for 7T or more.
This is a period of about 5 clocks of the channel clock CK.

The detection circuit 67 for 7T or more outputs the modulation data D3
, And outputs a detection pulse SP of one channel clock width when the pulse width is 7T or more (FIG. 9).
(G)).

That is, as shown in FIG. 10, in the 7T or more detecting circuit 67, the latch circuits 68A to 68H of eight stages are provided.
Latches and transfers the modulated data D3 sequentially in synchronization with the channel clock CK.

The AND circuit 69 includes these latch circuits 68
A to 68H latch outputs are input in parallel. At this time, the AND circuit 69 inverts the logic level of the latch output only for the last-stage latch circuit 68H and inputs it, and outputs a logical product signal of these parallel inputs. As a result, when the modulation data D3 is viewed at the cycle of the channel clock CK, the AND circuit 69 determines that when one logic 0 to seven logics 1 are continuous, that is, for the basic cycle T of the modulation data D3, An AND signal which rises to logic 1 only when a pit having a period of 7T or more is formed is output.

The latch circuit 70 latches the output of the AND circuit 69 and outputs a detection pulse SP.

The AND circuit 72 (FIG. 8) detects the detection pulse SP and the delay signal MSH output from the delay circuit 66.
An AND signal with D is output.

A monostable multivibrator (M
M) 73, using the output of the AND circuit 72 as a trigger, outputs a modulation pulse MMP (FIG. 9H) having a predetermined pulse width shorter than one cycle of the channel clock CK.
Here, the pulse width is determined when the irradiation of the laser beam L is temporarily stopped by the modulation pulse MMP.
In the optical disk created by the disk master 42, the pit width is reduced by the temporary stop, and the degree of the reduction is set to be about 10% of the average pit width.

The delay circuit 76 delays and outputs the modulated data D3 by a period of about 5 clocks. The exclusive OR circuit (XOR) 77 outputs the modulated data D3D (FIG. 9C) output from the delay circuit 76. )) And the modulation pulse M
Calculate exclusive OR with MP. Thus, a modulation signal S3 (FIG. 9 (I)) obtained by modulating the modulation data D3 with the control data SC1 is generated.

Thus, the delay time of the delay circuit 76 is set so that the edge position information of the pit detected at the time of reproduction in a pit having a period of 7T or more is not affected by a change in the pit width due to the modulation pulse MMP. Is set to Specifically, the delay time is set such that the switching of the logic level of the modulation signal S3 corresponding to the modulation pulse MMP is a timing separated by a predetermined period from the rising timing of the modulation data D3. In this embodiment, this timing is set so that the rising of the modulation pulse MMP is delayed by about 3T from the rising of the corresponding modulation data D3D. Further, by generating a modulation pulse MMP for a pit having a period of 7T or more, a modulation pulse MM is generated.
The fall of P is set so as to precede the fall of the corresponding modulated data D3D by about 3T or more.

FIG. 11 shows a master disc 42 formed by recording the digital audio signal D1 in this manner.
FIG. 4 is an exploded perspective view showing an optical disk 26 produced by the above. As shown in FIG. 12, the optical disk 26 has predetermined reflective films 78A and 78 on disk substrates 26A and 26B.
8B, the disk substrates 26A and 26B
Are laminated and a protective film 79 is attached.

At this time, in the optical disk 26, when the protective film 79 is on the upper layer side, the reflective film 78A attached to the lower disk substrate 26A is formed of a reflective film having wavelength selectivity. That is, the reflection film 78A is
A wavelength 650 for processing the information recording surface according to A
[Nm] laser beam L1 shows a high reflectivity, and transmits light to a 780 [nm] laser beam L2 having a wavelength of 780 [nm] to be processed on the information recording surface of the upper reflective film 78B. It is made to show sex.

Thus, the optical disk 26 is irradiated with the laser beams L1 and L2 having the wavelengths of 650 [nm] and 780 [nm] from the lower disk substrate 26A side, and receives the return light from each of the reflection films 78A and 78B. It has been made possible.

Each of the disk substrates 26A and 26B is made of, for example, a transparent resin such as polycarbonate by injection molding using a stamper, and each has a plate thickness that is half that of a compact disk.

At this time, the stamper used for producing the lower disk substrate 26A is produced from a mother disk produced by developing the disk master 42 exposed by the optical disk recording device 40 and then electroforming.

On the other hand, the stamper used to form the upper disk substrate 26B is the lower disk substrate 26B.
It is created by processing the same source as the digital audio signal D1 assigned to A in the same format as a conventional compact disc. That is, the stamper used to form the upper disk substrate 26B samples the digital audio signal at a sampling frequency of 44.1 [kHz], and then records the digital audio signal quantized by multi-bit by EFM modulation.

Thus, the optical disk 26 is loaded into a conventional compact disk player, and the upper reflective film 7
8B, the return light can be received, and the return light can be processed to reproduce an audio signal having the same content as the digital audio signal D1. The lower reflective film 78A is provided with an upper reflective film 78B.
A pit row is formed at a higher density, and a reproduced signal obtained from the lower reflective film 78A is processed by a dedicated reproducing device, and a digital audio signal with higher sound quality than the audio signal obtained from the upper reflective film 78B is processed. The signal D1 can be reproduced.

The upper reflective film 78B is partially enlarged.
As shown in FIG. 13, a lower reflective film 78A is formed in the upper reflective film 78B (FIG. 32).
(A)) In accordance with audio data, pits and lands are simply formed repeatedly by an integral multiple of one clock cycle T of the channel clock CK which is a basic cycle, whereas the lower reflective film 78A has In a pit having a period of 7T or more, as indicated by an arrow a,
The pit is formed so as to be locally separated from the leading edge of the pit by a predetermined distance L (a distance corresponding to the period 3T) according to the control data SC1, and the control data SC1 is recorded by the pit width. Will be done.

FIG. 14 is a block diagram showing a dedicated reproducing apparatus for reproducing the optical disk 26 manufactured as described above. In the reproducing device 27, the spindle motor M drives the optical disc 26 to rotate under the condition of a constant linear velocity under the control of the servo circuit 81.

The optical pickup P irradiates the optical disk 26 with a laser beam having a wavelength of 650 [nm] to obtain return light from the reflective film 68A below the optical disk 26, and the signal level is changed according to the amount of the return light. It outputs a changing reproduction signal RF. Here, the signal level of the reproduction signal RF changes corresponding to the pits formed on the reflection film 78A of the optical disk 26. At this time, on the optical disk 26, about 10% from the average pit width.
Since the pit width is formed only locally, the signal level of the reproduction signal RF changes in accordance with the pit width. However, since the pit width is set so as to be separated from the edge of each pit by a predetermined distance so as not to affect the timing of the edge, the timing at which the reproduction signal RF crosses the reference level for binary identification is determined by the pit width. The timing is maintained at the same timing as when the image is not created narrow.

The amplifier circuit 82 equalizes the waveform of the reproduced signal RF, amplifies the signal with a predetermined gain, and outputs the amplified signal. The binarizing circuit 83 converts the reproduced signal RF into a binary signal based on a predetermined reference level.
And a binarized signal BD is created. In order to hide
Since the degree of reduction in the local pit width on the optical disk 26 is 10%, this local reduction in the pit width is not detected in the binary signal BD.

The PLL circuit 84 operates based on the binary signal BD to reproduce the channel clock CCK of the reproduction signal RF.

The demodulation circuit 85 has a channel clock CC
By sequentially latching the binary signal BD with reference to K, the reproduction data corresponding to the modulation data D3 of the optical disc recording device 40 is reproduced. EFM (Eight to F
After demodulating the reproduced data, the demodulation circuit 85 divides the demodulated data into predetermined bits on the basis of a frame sync, deinterleaves the generated data in predetermined bits, and performs ECC (Error Corror).
ecting Code) is output to the decoder 86.

The ECC decoder 86 includes a demodulation circuit 85
Of the random access memory (R
AM) 87, and then read out the data in a predetermined order to deinterleave the reproduced data. Further, the ECC decoder 86 performs an error correction process on the output data based on the error correction code added to the reproduced data. As a result, the ECC decoder 86 reproduces the reproduction data corresponding to the modulation data D2 of the optical disc recording device 40.

The descrambler 88 is composed of the descramblers (DSCs) 29A to 29X described above with reference to FIG. 2 and the selection circuit 30. The descrambler 88 descrambles the reproduction data output from the ECC decoder 86 to obtain a digital audio signal. Decode D1. Here, the descramblers 29A to 29X are configured to correspond to the scramblers 25A to 25X described above with reference to FIG. 4, and operate by the disk key DK and the initial value IV set by the system control circuit 89 in sector units. Performs descrambling of the playback data. Similarly, the selection circuit 30 also includes a descrambler 29 corresponding to the scramblers 25A to 25X specified by the scrambler identification data SID output from the system control circuit 89.
A to 29X are selected and the result of descrambling is output.

The converter 90 includes a descrambling unit 88
The digital audio signal D1 is output in a predetermined format.

The system control circuit 89 controls the playback device 2
7 is configured by a computer that controls the operation of the computer. When the optical disk 26 is loaded, the system control circuit 89 controls the entire operation so as to access the lead-in area, thereby acquiring data such as TOC recorded in the lead-in area of the optical disk 26.

At this time, the system control circuit 89 simultaneously outputs the disk key DK, the initial pointer PIV, and the scrambler identification data SID detected by the detection section 91.
Is obtained, and the operation of the descrambler 88 is controlled at the time of reproducing the subsequent program area by the obtained disk key DK and scrambler identification data SID.

That is, the system control circuit 89 switches the contact point of the selection circuit 30 so as to select the descrambler specified by the scrambler identification data SID, whereby the output data of the ECC decoder 86 is decrypted. Set. The disk key DK is supplied to each of the descramblers 29A to 29X.

The system control circuit 89 detects the corresponding initial value IV held in the built-in memory from the initial pointer PIV acquired in the same manner. When the initial value IV is reproduced in the program area, the descrambler 88 To supply.

The detecting section 91 reproduces the control data SC1 from the reproduced signal RF output from the amplifier circuit 82, and uses the reproduced control data SC1 to generate the disc key DK, the initial pointer PIV, the scrambler identification data SI
D is output to the system control circuit 89.

FIG. 15 is a block diagram showing the detecting section 91 in detail. In the detection section 91, the synchronization pattern detection circuit 93, as shown in FIG. 16, uses the channel clock CCK (FIG. 16B) as a reference to convert the binary signal BD (FIGS. 16A-1 and 16A). -2)) are sequentially latched, and a frame sync is detected by judging the successive logic levels. Furthermore, a synchronous pattern detection circuit 9
Reference numeral 3 denotes a set pulse FSET whose signal level rises during a period of one channel clock CCK at which each frame starts, and a period of one channel clock CCK following this set pulse FSET with reference to the detected frame sync. And outputs a clear pulse FCLR at which the signal level rises (FIGS. 16D and 16C).

The pit detection circuit 94 is configured similarly to the detection circuit 67 of 7T or more of the optical disk recording device 40 (FIG. 8), and sequentially transfers the binarized signal BD with reference to the channel clock CCK, thereby obtaining a period of 7T. The timing of the binarized signal BD corresponding to the pit having the above length is detected. Further, the pit detection circuit 94 generates and outputs a rising signal PT whose signal level rises at the timing of the start of the detected pit. Further, it outputs a gate signal CT whose signal level rises with a delay of a predetermined period from this rising signal PT. The gate signal CT is supplied to the second modulation circuit 47 of the optical disk recording device 40.
Therefore, unlike the modulation pulse MMP, the signal level rises at each pit having a period of 7T or more, unlike the modulation pulse MMP.

The M-sequence generation circuit 95 initializes the address by the clear pulse FCLR supplied from the synchronization pattern detection circuit 93, and then sequentially advances the address by the channel clock CCK to access the built-in read-only memory. Thus, an M-sequence signal corresponding to the M-sequence signal MS generated by the optical disc recording device 40 is generated. Further, the M-sequence generation circuit 95 includes a pit detection circuit 94.
From the rising signal PT supplied from the
By latching and outputting the sequence signal, the M-sequence signal is latched at the timing of the start of a pit having a period of 7T or more, and the latched logic level is followed by the start of a pit having a period of 7T or more. An M-sequence latch signal MZ held until the time is output.

Analog-to-digital conversion circuit (A / D) 9
7 performs an analog-to-digital conversion process on the reproduction signal RF with reference to the channel clock CCK and outputs an 8-bit digital reproduction signal. Polarity inversion circuit (-1) 98
Outputs the digital reproduction signal with its polarity inverted.

The selector 99 receives a digital reproduction signal directly input from the analog-digital conversion circuit 97 and a digital reproduction signal input from the polarity inversion circuit 98 according to the logic level of the M-sequence latch signal MZ output from the M-sequence generation circuit 95. Selectively output a digital reproduction signal whose polarity is inverted. That is, when the M-sequence latch signal MZ is logic 1, the selector 99 selects and outputs the directly input digital reproduction signal. Conversely, when the M-sequence latch signal MZ is logic 0, the polarity is inverted. Select digital playback signal. This allows the selector 99 to output the M-sequence signal MS
And reproduces the logical level of the control data SC1 modulated by the multi-level data, and outputs the reproduction data RX based on the multi-level data.

The adder 100 is a 16-bit digital adder, and stores the reproduced data RX and the accumulator (AC
U) Output data AX of 101 is added and output. The accumulator 101 is configured by a 16-bit memory that holds the output data of the adder 100, and forms a cumulative adder together with the adder 100 by feeding back the held data to the adder 100. That is, the accumulator 1
01 clears the content held by the clear pulse FCLR, and then takes in the output data of the adder 100 at the timing of the gate signal CT. Thereby, the adder 10
0 accumulates the logical value of the reproduction data RX reproduced by the selector 99 for each frame and outputs the accumulated value AX.

The pit counter 102 outputs the clear pulse F
The contents held by CLR are cleared and the gate signal CT
, The accumulator 101 counts the number of pits that have been cumulatively added.
Output X.

The division circuit (÷) 103 averages the logical value of the reproduced data RX reproduced by the selector 99 by dividing the accumulated value AX output from the accumulator 101 by the count value NX. Binarization circuit 1
04 is a timing at which the set pulse FSET rises, and the output data B of the division circuit 103 is determined by a predetermined reference value.
X is binarized and output. Thereby, the reproduction data RX of the control data SC1 reproduced by the selector 99 is converted into the control data SC1.

The ECC circuit 105 controls the control data SC
Control data S by the error correction code CRC added to
C1 is subjected to error correction processing, and the disk key DK and the initial pointer PI assigned to the control data SC1.
V, and outputs the scrambler identification data SID to the system control circuit 89.

(2-2) Operation of Second Embodiment In the above configuration, in the manufacturing process of the optical disc 26 according to this embodiment (FIG. 2), the disc producing side 21 uses the scrambler identification data SID. Any one of the scramblers 25A to 25X is designated, and thereby the encryption processing mode is selected. Also disk key DK
Are set in each of the scramblers 25A to 25X, and the digital audio signal D1 encrypted by the scramble process using the disc key DK is recorded on the optical disc 26. In a pit having a period of 7T or more in the lead-in area of the optical disk 26, the disk key D
The pit width is modulated by the K, the scrambler identification data SID, etc., so that the disk key DK,
Scrambler identification data SID and the like are recorded.

As a result, on the reproducing apparatus 27 side, the disc key DK, the scrambler identification data SID, etc., which are recorded so as to be difficult to read, are reproduced, and the reproduced disc key DK, the scrambler identification data SID, etc. 29X is selected to set the decryption processing mode. With this processing mode, the digital audio signal D1 is decrypted using the disk key DK.

That is, in the manufacturing process of the optical disk 26,
In the optical disk recording device 40 (FIG. 3), after sampling at a sampling frequency of 2.8224 [MHz], the high-quality digital audio signal D1 quantized by 1 bit is sequentially exposed on the disk master 42 to form a mother disk. After being created, it is created from this mother disk.

In the exposure of the disk master 42, the digital audio signal D1 is converted in the scrambler 51 by the processing mode of the scramblers 25A to 25X selected by the scrambler identification data SID.
A disk key DK having a length of k bits and an initial value IV having a length of r bits are set for each sector and are sequentially encrypted (FIG. 4). As a result, the encoding process is difficult to analyze as compared to the case where the encryption process is simply performed by a single system scrambler. In addition, each scrambler 25A-2
Initial value IV different at 5X is the initial pointer P
Even when set by the IV (FIG. 5), it is difficult to identify which of the scramblers has been processed by encryption. Further, even when a digital audio signal D1 having a continuous logic 0 is input by the initial value IV, a scramble processing result D3 with a random logic level is output.

The digital audio signal D2 encrypted in this manner (FIG. 3)
After the error correction code is added together with the subcode data,
The data is interleaved, modulated by a predetermined modulation method, and converted into modulated data D3.

At this time, the modulation data D3 is the clock CK
In the range of 3T to 11T in which one cycle T is a basic cycle, the signal is generated in a reproduction system optical system with a period longer than the shortest period that can keep the intersymbol interference in the pit row direction within a practically sufficient range. It is generated so that the rising and falling of the level are repeated. The modulation data D3 is
A frame sync is interposed at predetermined intervals (FIG. 6), and is generated by a frame structure in units of sync frames.

The modulation data D3 based on the digital audio signal D1 generated in this way is supplied to the optical modulator 46 as the modulation signal S3 via the second modulation circuit 47 (FIG. 8). Is supplied to the optical modulator 46 via the second modulation circuit 47 as the modulation signal S3 through the second modulation circuit 47 instead of the digital audio signal D1.

As a result, the digital audio signal D1
Is that the optical modulator 46 is driven by the modulation signal S3 and T
The pits and lands are recorded on the master disc 42 together with the OC data string by repeating pits and lands with an integral multiple of the basic length corresponding to one cycle of the channel clock CK.

When converting the modulated data D3 into a modulated signal S3, the modulated signal S3 is set to correspond to the signal level of the modulated data D3 in an area other than the lead-in area.
In contrast, in the lead-in area, the logical level of the modulation data D3 is locally switched to generate a modulation signal S3. A pit with a small width is created (FIG. 13). As a result, the pit width is locally modulated, and the control data SC1 including the disk key DK, the scrambler identification data SID, the initial pointer PIV, and the error correction code CRC (16 bits) is recorded on the disk master 42.

That is, the control data SC1 constituted by randomly arranging the disk key DK, the scrambler identification data SID, the initial pointer PIV for specifying the initial value, and the error correction code CRC is one bit per frame (FIG. 7). Is supplied to the second modulation circuit 47 by a low-frequency binary number assigned with.

The M-sequence generation circuit 6 of the second modulation circuit 47
3 (FIG. 8), the M-sequence random number data M that is repeated in a frame cycle in synchronization with the channel clock CK.
S is generated, and the exclusive OR circuit 64 obtains an exclusive OR of the M-sequence random number data MS and the control data SC1. Thereby, the control data SC1
Is modulated by the random number data MS, and logical 1 and logical 0 appear with equal probability in the M-sequence random numbers. Therefore, the control data SC1 is converted into an exclusive OR signal MS1 in which logical 1 and logical 0 also appear with equal probability. Modulated. As a result, the control data SC1 is recorded on the optical disk 26 with difficulty in analysis.

Further, in the flip-flop circuit 65, the exclusive OR signal MS1 is latched at the rising edge of the modulation data D3 corresponding to the edge of each pit. Further, in the detection circuit 67 for 7T or more, the basic cycle T
Data D corresponding to pits having a period of 7T or more
2 is detected, and the AND circuit 7
2, the latch result of the flip-flop circuit 65 corresponding to the rise of the logic level is selected. As a result, the monostable multivibrator 73 is driven by the output of the AND circuit 72, and the exclusive OR circuit 77 locally switches the logical level of the modulation data D2 by the output of the monostable multivibrator 73.

Thus, control data SC1 has a period of 7T.
In the pits described above, the pit width is locally reduced and recorded on the master disk 42. In the master disk 42, when the logical product of the M-sequence random number data MS and the control data SC1 is logical 1 and the pit length is 7T or more, the pits are partially reduced and the pits are sequentially reduced. A column will be created.

Further, in order to generate the modulation signal S3 by switching the logic level of the modulation data D3 to create a narrow pit, the modulation pulse MMP output from the monostable multivibrator 73 is used. ,
The modulation data D3 is delayed by the delay circuit 76 and supplied to the exclusive OR circuit 77, so that the switching of the logical level of the modulation signal S3 does not affect the position information of the edge of the pit detected during reproduction. It is set as follows.

That is, on the premise that the pit width is reduced in a pit having a period of 7T or more, the switching of the logical level of the modulation signal S3 corresponding to the modulation pulse MMP is separated from the rising timing of the modulation data D3 by a predetermined period. The timing is set (corresponding to the distance L from the edge of the pit in FIG. 13) so that the rise of the corresponding modulation data D3D from the rise of the modulation pulse MMP precedes the period of about 3T or more.

Thus, the modulation pulse MMP is generated so that the pit width is reduced at a position separated from the front and rear edges by a minimum period of 3T or more that can sufficiently reduce the intersymbol interference in the pit row direction in the reproducing system. The generated digital audio signal D1 and TOC data can be reproduced by effectively avoiding the generation of jitter due to the change in the pit width. That is, a decrease in the phase margin in the reproduced signal is prevented.

The pulse width of the modulating pulse MMP output from the monostable multivibrator 73 is set to a length shorter than one cycle of the channel clock CK, whereby the pit width is set to 10% of the average pit width. The width is reduced, and a narrow pit is locally formed. This also prevents a decrease in the amplitude margin due to the recording of the control data SC1, and prevents erroneous binary identification of the reproduction signal RF.

Further, control data SC1 is recorded by locally reducing the pit width by 10%, and control data SC1 is further modulated by M-sequence random number data MS in which logic 1 and logic 0 appear with equal probability. As a result, a change in the reproduction signal RF due to a change in the pit width is observed as noise mixed in the reproduction signal RF.
C1 can be made difficult to observe and discover. Further, it is possible to make it difficult to physically copy the pit width changed by the control data SC1.

In addition to these, by allocating one bit of the control data SC1 to one frame, even if the reproduced signal fluctuates due to noise or the like, the control data SC1 can be reliably transmitted.
1 can be played.

That is, the disk master 42 exposed in this manner is developed and electroformed to be processed into a mother disk, and a stamper is formed from the mother disk. Further, a disk substrate 26A in the lower layer of the optical disk 26 is formed by injection molding using the stamper (FIGS. 11 and 12).

Further, according to a conventional compact disk creation method, a stamper created by recording a digital audio signal having a sampling frequency of 44.1 [kHz] and multi-bit quantization generated from the same source as the digital audio signal D1 is used. A disc substrate 26B on the upper layer of the optical disc 26 is formed.
The optical disks 26 are created by laminating A and 26B.

The optical disk 26 created as described above
(FIG. 14), the reproducing device 27 detects a reproduced signal RF whose signal level changes in accordance with the amount of return light obtained by irradiating a laser beam, so that the signal level of the reproduced signal RF is changed to a pit. The reproduced signal RF is changed by the binarization circuit 83 to a value corresponding to the width.
Valued. Subsequently, after the binarized signal BD is demodulated by the demodulation circuit 85, it is deinterleaved and error-corrected by the ECC decoder 86, whereby the encrypted digital audio signal D1 is reproduced. In the lead-in area, TOC data is reproduced by the same processing of the reproduction signal RF.

At this time, in the optical disk 26, the local pit width is reduced by a pit having a period of 7T or more, and separated from the pit edge (both the front edge and the rear edge) by a distance corresponding to the period 3T. Since the pit width is reduced, the beam spot by the laser beam scans the pit edge and the portion where the pit width is reduced at different timings, thereby reproducing the reproduction signal RF.
In the above, the effect of locally reducing the pit width is avoided. That is, in the optical disk 26, a change in signal level near each edge due to the narrowing of the pits is prevented, so that even in the optical disk 26 in which the control data SC1 is recorded in the lead-in area, the program area is reproduced. As in the case, the reproduction signal RF can be binary-identified at the correct timing, and the TOC data can be reproduced correctly.

In the reproduction of the digital audio signal D1 and the TOC data executed as described above, the optical disk 26 reproduces the control data SC1 recorded in advance in the lead-in area by the pit width, and scrambles the control data SC1. The processing mode of the descrambling by the descramblers 29A to 29X is selected from the blur identification data SID. The key data DK of the control data SC1 is set in the descramblers 29A to 29X in sector units, and the initial values of the descramblers 29A to 29X specified by the initial pointer PIV are similarly set in the descramblers 29A to 29X in cluster units.
Set to 9X. As a result, the playback device 27 performs the decryption process corresponding to the encryption process in the optical disk recording device 40, thereby performing the digital audio signal D1.
Is decrypted and output.

On the other hand, in the reproduction of the control data SC1 in the lead-in area (FIG. 15), the optical disk 26 detects a frame sync in the synchronous pattern detection circuit 93 and uses the M-sequence as a reference based on the detection of the frame sync. The generation circuit 95 generates random number data MZ corresponding to the M-sequence random number data at the time of recording.

The reproduction signal RF is converted into a digital reproduction signal by the analog-to-digital conversion circuit 97, and the digital reproduction signal or the digital reproduction signal obtained by inverting the polarity is selected by the selector 99 based on the M-sequence random number data MZ. As a result, the control data SC1
Is reproduced by expressing the logical level of the data by multi-valued data.

The reproduction data RX has a pit width of 10
Since only [%] is reduced, the SN ratio becomes extremely poor when viewed in units of one sample. Optical disk 2
6, the reproduced data RX is stored in the accumulator 1
After being accumulated in frame units by 01 and the adder 100, they are divided by the division circuit 103 and averaged, thereby improving the SN ratio. Thus, this division circuit 1
03 is binarized by the binarization circuit 104 to decode the control data SC1, and then the ECC circuit 1
The error correction processing is performed by the control circuit 05 and output to the system control circuit 89 (FIG. 14). Further, the system control circuit 8
In step 9, predetermined bits are selectively extracted from the control data SC1 in which the disk identification data SID and the like are randomly arranged, and the disk identification data SID, the key data DK, and the initial pointer PIV are reproduced.

(2-3) Effects of the Second Embodiment According to the above configuration, the control data SC1 is generated from the key data and the identification data for specifying the decryption processing mode. To record the digital audio signal D1 while recording the control data SC1 by locally changing the pit width at a timing that does not affect the position information of the edge of the pit detected during reproduction. Accordingly, the control data SC1 can be recorded in a manner that is difficult to analyze and find, and that physical copying is difficult. Thereby, illegal copying can be remarkably eliminated as compared with the related art.

Further, an initial value IV is set for each encryption processing mode, and an initial pointer PIV for specifying the initial value is assigned to control data, so that even when the same processing mode is selected, the encryption processing is performed. As a result, the control code and the digital audio signal can be recorded with difficulty in detecting the identity of this processing mode, and thereby illegal copies can be effectively eliminated.

The control data SC is randomly arranged.
Also, the creation of No. 1 makes it difficult to analyze the control data, so that illegal copying can be effectively eliminated.

Further, by modulating the control data SC1 with a random number and modulating the pit width, the control data SC1 can be recorded with difficulty in distinguishing it from noise, and the analysis of the control data recorded by the pit width can be made difficult. . At the time of reproduction, the influence of noise is effectively avoided and the control data SC1
Can be played.

Further, by recording the control data in the lead-in area, the TO
At the time of reproducing the C data, the control data can be reproduced at the same time, thereby making it difficult to decode the control data reproduction process.

Also, by setting disc identification data and the like in sector units, it is possible to reproduce a digital audio signal from a desired location and to decrypt the data in random reproduction or the like.

Further, by selecting a pit having a length equal to or longer than a predetermined length and changing the pit width at a position separated from the edge of the pit by 3T or more, the position information of the edge of the pit detected during reproduction is not affected. At the timing, the control data SC1 can be recorded by locally changing the pit width. In particular, as shown in FIG.
When the pit width is changed at a location separated by T or more, the digital audio signal D recorded in the program area is changed.
Using the optical pickup that reproduces the data No. 1, the same phase margin and amplitude margin as in the case of reproducing the program area are ensured, the TOC data can be reproduced, and the control data SC1 can be recorded. Thereby, the control data SC
1 can be used to eliminate piracy.

At this time, in the second modulation circuit, a pit having a length equal to or more than the period corresponding to the period 7T is detected, and at a timing separated from the timing corresponding to the edge of the detected pit by a predetermined period in accordance with the control data SC1. By generating the modulation signal S3 by inverting the logic level of the modulation data D3, the TO by the pit train can be easily and reliably achieved.
The control data SC1 can be recorded without affecting the reproduction of the C data.

Also, by setting the change in the pit width to 10% of the average width of the pits, the control data SC1 can be similarly recorded with difficulty in distinguishing from the noise, and the control data SC1 is difficult to find and analyze. Can be

In the reproducing apparatus, the signal level of the reproduced signal RF is detected to decode the control data SC1, and the average value of the signal level is detected to remove the influence of noise mixed in the control data, thereby reducing the noise. The control data SC1 recorded so as to be difficult to identify can be reliably reproduced.

At this time, the accumulator 101 and the accumulator by the adder 100 and the pit counter 102
, The number of appearances in one frame is indefinite, and the period is 7T.
The control data SC1 recorded by being assigned to the pits can be reliably reproduced.

(3) Other Embodiments In the above embodiment, the case where control data is modulated by M-sequence random number data synchronized with the channel clock CK has been described. However, the present invention is not limited to this.
For example, modulation data D2 instead of channel clock CK
May be supplied to the M-sequence generation circuit 63 to generate M-sequence random number data in synchronization with the modulation data D3.

In the above-described embodiment, a case has been described in which control data is recorded by modulating the pit width for pits having a period of 7T or more. However, the present invention is not limited to this.
In the case where the reproducing system has a sufficient margin for the jitter of the reproducing signal, the same effect can be obtained by modulating the pit width of the pit having a period of 6T or more.

In the above embodiment, the case where the pit width is reduced by a predetermined distance from the edge of the pit has been described. However, the present invention is not limited to this, and FIG.
As shown in (2), for pits having a predetermined length or more, the pit width may be reduced at the center of each pit.

Further, in the above-described embodiment, a case has been described where the pit width is modulated by locally inverting the logical level of the modulation data D3. However, the present invention is not limited to this, and the light amount of the laser beam is modulated. By doing so, the pit width may be modulated. In this way, as shown in FIG. 17B, the pit width can be modulated so that the pit width locally increases. Further, as shown in FIG. 17C, control data can be recorded in three values by locally increasing and decreasing the pit width, and the degree of the increase and the degree of the reduction are set stepwise. Thus, the control data can be recorded by multi-value recording of more than three values.
Further, as shown in FIG. 17D, the sub-data can be recorded by changing the pit width in a period longer than one cycle of the channel clock.

Further, in the above-described embodiment, a case has been described in which one bit of control data is allocated to one frame and recorded. However, the present invention is not limited to this. Various types of allocation methods can be applied, such as when 1-bit control data is allocated to a pit, or when a plurality of bits of control data are sequentially and cyclically allocated to pits having a predetermined length or more for a predetermined period. When 1-bit control data is assigned to each predetermined number, the pit counter 1
02, the division circuit 103 can be omitted.

Further, in the above-described embodiment, a case has been described in which one of a plurality of scramblers and descramblers is specified by scrambler identification data to select an encryption processing mode. The present invention is not limited to this, and the scramble unit and the descramble unit may be configured by one arithmetic processing circuit, and the processing form in the arithmetic processing circuit may be switched by the scrambler identification data.

Further, in the above-described embodiment, in addition to the disk key composed of the key data, the identification data for specifying the decryption processing mode, the control data is constituted by the initial pointer for specifying the initial value and the error correction code. Although the case has been described, the present invention is not limited to this, and when practically sufficient, the control data may be configured by omitting the initial pointer for specifying the initial value and the error correction code.

Further, in the above-described embodiment, a case has been described in which a sub-data string composed of control data is recorded with a pit width. By changing the data locally, the width of the land may be changed to record the sub data. In this case, the reproducing device detects the signal level of the reproduction signal at the time of the fall of the signal level of the reproduction signal corresponding to the land and reproduces the sub data.

In the above-described embodiment, a case has been described in which a sub data sequence is recorded by modulating the pit width of the lead-in area with respect to a main data sequence composed of pits and lands. The present invention is not limited to this, and the pit width can be modulated in various areas such as a program area to record sub data. In these cases, the pit width may be changed even in an area where no sub data is recorded, thereby making it difficult to decode the area where the sub data is recorded.

Further, in the above-described embodiment, a case has been described in which the digital audio signal and the control data are reproduced by binarizing the reproduced signal and the like. However, the present invention is not limited to this, and various methods such as Viterbi decoding are used. Can be widely applied.

In the above-described embodiment, a digital audio signal having a sampling frequency of 44.1 [kHz] and a multi-bit quantization bit, and a sampling frequency of 44.1 [kHz] × n (n is an integer of 2 or more) ) Has been described in the case where a digital audio signal whose quantization bit is 1 bit is recorded on the information recording surface on which each is laminated, but the present invention is not limited to this, and the sampling frequency is 4
8 [kHz], a digital audio signal having a multi-bit quantization bit, and a sampling frequency of 48 [kHz]
The present invention can be widely applied to a case where a quantized bit of z] × n (n is an integer of 2 or more) records a multibit digital audio signal.

In the above-described embodiment, the case where the pit width is changed for one information recording surface by applying to an optical disc having two information recording surfaces has been described. However, the present invention is not limited to this. The present invention can be widely applied to a case where the pit width is changed for each layer, and a case where the pit width is changed in an optical disc having one information recording surface. In this case, data to be recorded in the program area of the other information recording surface may be encrypted by key data to be recorded in the lead-in area of one information recording surface.

In the above-described embodiment, the case where desired data is recorded on the optical disk by the stamper has been described. However, the present invention is not limited to this. Can be widely applied. When the present invention is applied to optical discs including magneto-optical discs in general, marks and spaces, which are superordinate concepts including pit lengths and inter-pit intervals, are recorded by modulating main data by the lengths of the marks and spaces. Therefore, the key data and the like are recorded by modulating the width of the mark or space. Thus, in this specification,
Marks and spaces are meant to include pits and between pits. When the present invention is applied to a magneto-optical disk device in this manner, the present invention can be applied regardless of the presence or absence of a pre-groove and the presence or absence of a meandering pre-groove.

In the above-described embodiment, the case where the present invention is applied to the case of recording a digital audio signal has been described. However, the present invention is not limited to this, and various optical disks such as a video disk and peripheral devices thereof are used. Can be widely applied to.

[0162]

As described above, according to the present invention, a sub data sequence is created by key data necessary for decrypting a main data sequence and data for specifying a decryption processing mode, and the sub data sequence is detected during reproduction. By recording the secondary data string by locally changing the width of pits or the like at a timing that does not affect the position information of the edge, illegal copying can be effectively avoided. According to the present invention, illegal copying can be effectively avoided by recording key data of data to be recorded by the modulation in the length direction of the mark and the space by the modulation in the width direction of the mark or the space.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an information transmission path according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an information transmission path according to a second embodiment of the present invention.

FIG. 3 is a block diagram showing an optical disc recording device according to the embodiment of the present invention.

FIG. 4 is a block diagram showing a scrambler of the optical disk device of FIG. 3;

FIG. 5 is a table showing initial values set in the scrambler of FIG. 4;

FIG. 6 is a time chart showing a relationship between a frame and a frame sync.

FIG. 7 is a chart showing control data.

FIG. 8 is a block diagram illustrating a second modulation circuit of FIG. 3;

FIG. 9 is a time chart for explaining the operation of the second modulation circuit in FIG. 8;

FIG. 10 is a block diagram showing a 7T or more detection circuit of FIG. 9;

11 is an exploded perspective view showing an optical disk 26 created by the optical disk recording device of FIG.

FIG. 12 is a sectional view of FIG. 11;

FIG. 13 is a plan view showing a pit shape of the optical disc of FIG. 11;

FIG. 14 is a block diagram showing a reproducing apparatus for reproducing the optical disc of FIG. 11;

FIG. 15 is a block diagram illustrating a detection unit of the playback device of FIG. 14;

FIG. 16 is a time chart for explaining the operation of the detection unit in FIG. 15;

FIG. 17 is a plan view showing a pit shape of an optical disc according to another embodiment.

FIG. 18 is a schematic diagram illustrating an example of a conventional copy protection system.

FIG. 19 is a schematic diagram illustrating another example of a conventional copy protection system.

[Explanation of symbols]

20: information transmission path, 25A to 25X, 113: scrambler, 26, 119 ... optical disc, 27, 1
24 ... playback device, 28 ... detection unit, 29A to 29X,
Reference numeral 122: descrambler, 40: optical disk recording device, 42: disk master, 46: optical modulator, 47
... Second modulation circuit 51 51 Scramble section 52
Modulation circuit, 63... M sequence generation circuit, 76... 7T or more detection circuit, 111.

Claims (44)

[Claims] An optical disk recording apparatus for irradiating an optical disk with a laser beam and sequentially creating a mark and a space on the optical disk based on a predetermined modulation signal, comprising: a main data encrypted using predetermined key data; A modulating signal generating means for generating the modulating signal whose signal level switches at a period of an integral multiple of a predetermined basic period based on a column; and a timing which does not affect position information of the edge of the mark detected during reproduction. And based on the secondary data column,
Laser light amount switching means for intermittently switching the light amount of the laser beam and locally changing the width of the mark or space to record the sub data sequence, wherein the sub data sequence is at least the An optical disc recording apparatus comprising: key data; and identification data that specifies a processing mode for decrypting the main data string using the key data. 2. The method according to claim 2, wherein the laser light amount switching means arranges the sub data strings in a random arrangement,
2. The optical disk recording apparatus according to claim 1, wherein the light amount of the laser beam is switched according to the arranged sub data sequence. 3. The laser light amount switching unit modulates the sub data sequence with a random number and outputs a modulation result by a random number, and switches the light amount of the laser beam according to the modulation result by the random number. The optical disk recording device according to claim 1, further comprising a light modulating unit. 4. The optical disk recording apparatus according to claim 1, wherein said laser light amount switching means switches the light amount of said laser beam in a lead-in area of said optical disk. 5. A laser light amount switching means, comprising: a detecting means for detecting a mark or space of a predetermined length or more and outputting a detection result; and detecting a mark or space of the predetermined length or more based on the detection result. A signal generating means for generating a timing signal for switching a signal level at a timing separated by a predetermined time from a timing corresponding to an edge; and a light for switching a light amount of the laser beam at a timing of the timing signal based on the sub data sequence. 2. The optical disk recording device according to claim 1, further comprising a modulation unit. 6. The optical disk recording apparatus according to claim 5, wherein the predetermined length is about six times as long as the length corresponding to the basic period. 7. The optical disk recording apparatus according to claim 5, wherein the predetermined time is a time corresponding to three times the basic period. 8. A recording method of an optical disk for recording a main data sequence by sequentially creating marks and spaces with a length equal to an integral multiple of a predetermined basic length, wherein the main data sequence is a predetermined key The data recording method is a data string encrypted using data, and the recording method of the optical disc includes locally changing the width of the mark or space at a timing that does not affect the position information of the edge of the mark detected during reproduction. Recording a sub data sequence by changing the sub data sequence, at least the key data,
An optical disc recording method, comprising identification data for specifying a processing mode for decrypting the main data string using the key data. 9. The method according to claim 8, wherein after arranging the sub data strings in a random arrangement, the width of the mark or space is locally changed in accordance with the arranged sub data strings. Recording method of an optical disc according to any one of the above. 10. The method according to claim 10, wherein the sub data sequence is modulated by a random number,
9. The optical disk recording method according to claim 8, wherein the width of the mark or the space is locally changed according to the modulation result. 11. The recording method for an optical disk according to claim 8, wherein a width of said mark or space is locally changed in a lead-in area of said optical disk. 12. The mark or space having a predetermined length or more, wherein the width of the mark or space is locally changed at a timing separated by a predetermined time from a timing corresponding to an edge of the mark or space. The optical disk recording method according to claim 8, wherein: 13. The apparatus according to claim 1, wherein the predetermined length is about six times as long as the length corresponding to the basic period.
3. The method for recording an optical disc according to item 2. 14. The apparatus according to claim 12, wherein said predetermined time is a time corresponding to three times the basic period.
Recording method of an optical disc according to any one of the above. 15. A length which is an integral multiple of a predetermined basic length,
In an optical disc on which marks and spaces are sequentially created and a main data string is recorded, the main data string is a data string encrypted using predetermined key data, and the optical disc is detected during reproduction. At a timing that does not affect the position information of the edge of the mark, based on the sub data sequence,
The sub data string is recorded by locally changing the width of the mark or the space, and the sub data string is at least the key data and the encryption of the main data string using the key data. An optical disc characterized by comprising identification data for specifying a processing mode for canceling a disc. 16. The optical disk according to claim 15, wherein said sub data sequence is recorded in a random arrangement. 17. The optical disk according to claim 15, wherein the sub data sequence is recorded after being modulated by a random number. 18. The optical disk according to claim 15, wherein said sub data sequence is recorded in a lead-in area. 19. The sub-data sequence is characterized in that, in the mark or space having a predetermined length or more, the width of the mark or space is modulated at a position separated by a predetermined distance from an edge, and recorded. The optical disc according to claim 15. 20. The apparatus according to claim 1, wherein the predetermined length is about six times a length corresponding to the basic period.
10. The optical disc according to 9. 21. The apparatus according to claim 19, wherein the predetermined distance is a distance corresponding to a time three times the basic period.
An optical disk according to claim 1. 22. The optical disk according to claim 15, wherein said optical disk has at least two information recording surfaces, and said main and sub data strings are recorded on at least one information recording surface. 23. At least two information recording surfaces, wherein the main and sub data sequences are recorded on one information recording surface, and the main data sequence is an integral multiple of a frequency of 44.1 [kHz]. The digital audio signal is a digital audio signal sampled at one sampling frequency and quantized by one bit, and is digitally sampled at another information recording surface at a sampling frequency of 44.1 [kHz] and quantized by multiple bits. The optical disc according to claim 15, wherein a signal is recorded. 24. At least two information recording surfaces, wherein the main and sub data sequences are recorded on one information recording surface, and the main data sequence is sampled at an integral multiple of a frequency of 48 [kHz]. It is a digital audio signal sampled by a frequency and quantized by 1 bit, and a digital audio signal sampled by a sampling frequency of 48 [kHz] and quantized by a multi-bit is recorded on another information recording surface. The optical disk according to claim 15, wherein: 25. A data sequence recorded on the optical disk is detected by detecting return light obtained by irradiating the optical disk with a laser beam, and performing signal processing on a reproduction signal whose signal level changes according to the return light. An optical disc reproducing apparatus for reproducing, comprising: a clock reproducing means for reproducing a clock based on the reproduced signal; and a first reproducing for reproducing a main data sequence by binary-identifying the reproduced signal based on the clock. Means, signal processing of the reproduction signal with reference to the clock, second reproduction means for reproducing a sub data sequence, and encryption of the main data sequence by identification data assigned to the sub data sequence. Set the processing mode to cancel the conversion,
Decryption means for decrypting the main data string using key data allocated to the sub data string, wherein the second reproducing means performs the reproduction based on the clock. Signal level detecting means for detecting a signal level of the reproduced signal and outputting a signal level detection result at a timing separated by a predetermined time from a timing at which the signal crosses a reference level for binary identification; and determining the signal level detection result. An optical disc reproducing apparatus, comprising: a judging means for reproducing the sub data sequence. 26. The optical disc reproducing apparatus according to claim 25, wherein said judging means reproduces said sub data sequence by averaging said signal level detection results. 27. The optical disk reproducing apparatus according to claim 25, wherein said judging means reproduces the key data and the identification data by extracting predetermined bits of the reproduced sub data sequence. 28. The apparatus according to claim 28, wherein the determination means selectively processes the signal level detection result based on a predetermined random number synchronized with the reproduction signal to reproduce the sub data stream. Item 30. The optical disk reproducing device according to item 25. 29. The optical disk reproducing apparatus according to claim 25, wherein said judging means reproduces said sub data sequence in a lead-in area of said optical disk. 30. An optical disk reproducing method for reproducing an optical disk in which marks and spaces are sequentially created, wherein a main data string recorded by the length of the marks and spaces is encrypted using predetermined key data. Decrypting by a predetermined decryption processing mode, reproducing the sub data sequence recorded by the change in the local width of the mark or space, and processing the key data and the decryption process from the sub data sequence. A method for reproducing an optical disk, comprising detecting a form. 31. The method according to claim 30, wherein the sub data sequence is reproduced by averaging a signal level of a reproduction signal corresponding to the local width change. 32. The optical disk reproducing method according to claim 30, wherein predetermined bits of the reproduced sub data sequence are extracted to detect the key data and identification data for specifying the processing mode. 33. The method according to claim 33, wherein the sub data sequence is reproduced by selectively processing a signal level of a reproduction signal corresponding to the local width change with reference to a predetermined random number. 30. The method for reproducing an optical disc according to 30. 34. The method according to claim 30, wherein the sub data sequence is reproduced in a lead-in area of the optical disk. 35. Irradiating an optical disk with a laser beam,
An optical disc recording apparatus for sequentially recording marks and spaces on the optical disc and recording main data, comprising: key data generating means for generating predetermined key data; and encrypting the main data using the key data. Encryption means for generating encrypted data; main modulation means for modulating the mark and space in the length direction according to the encrypted data; and modulation of the width of the mark or space according to the key data. An optical disc recording apparatus, comprising: 36. The optical disc recording apparatus according to claim 35, wherein said sub-modulating means modulates the width of said mark or space in a lead-in area of said optical disc. 37. The sub-modulating means includes: a length detecting means for detecting a mark or space of a predetermined length or more and outputting a length detection result; and a random number generating means for generating a random number. 4. The method according to claim 3, wherein the width of the mark or the space is modulated based on a length detection result and the random number.
6. The optical disk recording device according to 5. 38. Irradiating an optical disk with a laser beam,
In a method for recording an optical disk, in which marks and spaces are sequentially created on the optical disk to record main data, the main data is encrypted using predetermined key data to generate encrypted data, and the encrypted data is An optical disk recording method, wherein the mark and the space are modulated in a length direction in accordance with the key data, and the width of the mark or the space is modulated in accordance with the key data. 39. A length of an integral multiple of a predetermined basic length,
In an optical disk in which marks and spaces are sequentially created and desired data is recorded, the program area records the data encrypted using predetermined key data by modulation in the length direction of the marks and spaces. An optical disc, wherein the key data is recorded in a lead-in area by modulating the mark or space in a width direction. 40. The optical disk according to claim 39, wherein said key data is recorded after being modulated by a random number. 41. Key data having at least two information recording surfaces, wherein the key data recorded on one information recording surface decrypts data recorded in a program area of the other information recording surface. 40. The optical disk according to claim 39, wherein: 42. Data having at least two information recording surfaces, wherein data recorded in a program area of one of the information recording surfaces is a multi-bit digital audio signal quantized at a predetermined sampling frequency. 40. The optical disc according to claim 39, wherein the data recorded in the program area on the information recording surface is a 1-bit digital audio signal quantized at a sampling frequency that is an integral multiple of the sampling frequency. 43. A mark and a space are sequentially created,
In the program area, data encrypted by using predetermined key data is recorded by the modulation in the length direction of the mark and the space, and in the lead-in area, the data is modulated by the modulation in the width direction of the mark or the space. An optical disk reproducing apparatus for reproducing an optical disk on which key data for decrypting encrypted data is recorded, wherein the key data is detected by detecting a change in a width direction of the mark or space from the lead-in area. Key data reproducing means for reproducing the key data reproduced by the key data reproducing means, and decryption means for decrypting data recorded in the program area based on the key data reproduced by the key data reproducing means. Optical disc playback device. 44. A mark and a space are sequentially created,
In the program area, data encrypted using predetermined key data is recorded by the modulation in the length direction of the mark and the space, and in the lead-in area, the data is modulated by the modulation in the width direction of the mark or the space. What is claimed is: 1. An optical disc reproducing method for reproducing an optical disc on which key data for decrypting encrypted data is recorded, comprising: detecting a change in a mark or space width direction from the lead-in area; A method for reproducing an optical disk, comprising: reproducing data; and decrypting data recorded in the program area based on the key data.