JP2001357533A - Optical disk, its recorder, recording method and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk recorder or the like which is capable of preventing the illicit copying of the whole of an optical disk recorded with digital written works as it is. SOLUTION: This optical disk device has a formatter 1 which forms the channel signal corresponding to main digital information, a secret key memory section 1c which stores sub-digital information (secret key), a pseudo random- number generator 2 which generates pseudo random-number sequences, an XOR 4 which logically inverts the pseudo-random number sequences in accordance with the respective bits of the secret key, a PE modulator 5 which forms a PE modulation signal in accordance with the logically inverted pseudo random- number sequences, a phase modulator 6 which advances the phase of the edge of the channel signal by a specified slight time when the PE modulation signal is '1' and delays the phase of the edge of the channel signal by a specified slight time when the PE modulation signal is '0' and a recording channel 7 for forming recording marks in a DVD 9 based on the channel signal to be modulated which is formed by the phase modulator 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc, a recording apparatus, a recording method, and a reproducing apparatus, and more particularly, to a technique for recording sub-digital information on an optical disc while embedding sub-digital information in main digital information.

[0002]

2. Description of the Related Art DVD (Digital Versatile / Video Dis
An optical disk represented by c) is widely used as a medium for recording large-capacity digital data such as AV (Audio Video) data and computer data. For example, a high-quality moving image of two hours or more is recorded on a DVD-ROM and sold. In order to ensure the sound distribution of such digital works, a technique for preventing digital works on a recording medium from being illegally copied to another recording medium is required.

[0003] As a conventional technique for preventing unauthorized copying,
There is a method called content encryption (see Nikkei Electronics Nov. 18, 1996, p. 13-14). FIG. 30 is a diagram for explaining the method and shows a general recording area of a DVD. In this conventional method, compressed digital content such as a movie is encrypted using a three-level secret key (title key, disk key, master key), and then the encrypted content is accessed by a user who can access the content. It is recorded in the information area 9a. Of the encryption keys, the most important master key is notified only to the licensed DVD manufacturer, and the disc key and title key required for each DVD and each title are notified. After encryption based on the master key, the data is stored in a control information area (lead-in area) 9b that cannot be accessed by the user.

[0004] This makes it impossible to decrypt the encrypted content by an unauthorized DVD playback device that has not received a license. Therefore, a large number of DVDs on which unencrypted digital works are recorded are manufactured and sold. Misconduct such as doing so is prevented. Also, JP-A-11-39721
As described in Japanese Patent Application Laid-Open Publication No. H10-209, there has been proposed a method in which copy guard information is hidden on an optical disk to prevent illegal duplication by applying FM modulation to a reference clock or the like.

[0005]

However, these prior arts cannot prevent so-called piracy. For example, a DVD is mounted on one of the two spindle motors that are completely rotationally synchronized, and a duplicate master is mounted on the other, and a data stream reproduced from the DVD is reproduced and synchronized using a PLL to generate a bit stream. However, if this bit stream is recorded as it is, duplication can be easily performed.

That is, the contents of the entire storage area of the DVD, including the copy guard information and the control information area, are not changed to other DVs.
If a dead copy is made to D, a regular DV
Similarly to D, the encrypted content is read and decrypted by the licensed DVD device. This can prevent unauthorized production of a DVD storing unencrypted contents, but cannot prevent illegal operation of illegally copying a DVD storing encrypted contents in its entirety. If such a pirated version were to be available on the market at low cost, the copyright of the content would be violated.

Accordingly, the present invention has been made in view of such a problem, and an optical disk capable of preventing an optical disk on which a digital work has been recorded from being illegally copied as it is, a recording apparatus thereof, It is an object to provide a recording method, a reproducing device, and the like.

[0008]

In order to achieve the above object, an optical disk according to the present invention is an optical disk on which main digital information and sub digital information are recorded, wherein the main digital information is recorded on a track of the optical disk. Expressed by the presence or absence of pits formed at the discrete reference positions above,
The sub-digital information is represented by whether or not the position of the pit is displaced by a very small amount with respect to the reference position.

An optical disk recording apparatus according to the present invention is an apparatus for superimposing sub digital information on main digital information and recording the same on an optical disk, wherein pits are formed at discrete reference positions on tracks of the optical disk. Main digital information recording means for recording the main digital information, and sub-digital information recording means for recording the sub-digital information by displacing the pit position with respect to the reference position by a very small amount. Features.

More specifically, a formatter for generating a channel signal corresponding to the main digital information, a secret key storage unit for storing the sub digital information (secret key), a pseudo random number generator for generating a pseudo random number sequence, An XOR that logically inverts the pseudo-random number sequence based on each bit of the secret key, and a POR that generates a PE modulation signal based on the logically inverted pseudo-random number sequence
An E modulator that advances the phase of the edge of the channel signal when the PE modulation signal is "1" by a fixed minute time, and advances the phase of the edge of the channel signal when the PE modulation signal is "0" An optical disc recording apparatus may be provided with a phase modulator that delays by a very short time and a recording channel for forming a recording mark on a DVD based on a modulated channel signal generated by the phase modulator.

An optical disk reproducing apparatus according to the present invention is an optical disk reproducing apparatus in which main digital information and sub digital information are recorded, wherein pits formed at discrete reference positions on tracks of the optical disk are recorded. Main digital information reproducing means for reproducing main digital information by detecting; a clock extracting means for extracting a channel bit clock synchronized with the reference position from a channel signal corresponding to the detected pit row; And a sub-digital information extracting means for extracting sub-digital information based on a phase difference from the channel bit clock.

An apparatus for reproducing an optical disk on which main digital information and sub digital information are recorded, wherein the main digital information is reproduced by detecting pits formed at discrete reference positions on tracks of the optical disk. Main digital information reproducing means, radial error detecting means for detecting a displacement of the detected pit position in the radial direction from the track center, and sub digital information for extracting sub digital information based on the detected displacement. It may be configured to include an extraction unit.

An apparatus for reproducing an optical disk, wherein the optical disk has an information pit string formed by a predetermined reference clock and a pit string having a phase error added locally to form copy guard information. May be formed, and the apparatus may include means for identifying copy guard information based on a change in amplitude of a phase comparison error of a PLL.

Further, the present invention can also be realized as a recording method and a reproducing method in which characteristic components of the optical disk recording apparatus and the reproducing apparatus are steps.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. [Optical Disk Recording Device] FIG. 1 is a block diagram showing a configuration of a characteristic portion of an optical disk recording device 100 according to the present invention. The main signals B shown in FIG.
The waveforms of D, E, and F are as shown in the timing chart of FIG. Also, the blocks surrounded by double lines are
This indicates that the components are implemented in a secret state, for example, they are implemented in a manner that cannot be easily deciphered from the outside, such as realized by a circuit confined in one LSI.

The present apparatus 100 not only records main digital information by forming recording marks at discrete reference positions on tracks of an optical disc, but also records edges of recording marks at that time (in the track direction of the recording marks in the track direction). DVD-R having a function of simultaneously recording while embedding hidden information such as a watermark (here, a 56-bit secret key) as sub-digital information in main digital information by phase-modulating the edge that determines the length.
A recording device for an OM; a formatter 1, a pseudorandom number generator 2, a timing generator 3, an exclusive OR gate 4,
It includes a PE (Phase Encoding) modulator 5, a phase modulator 6, a recording channel 7, and a recording head 8.

The formatter 1 modulates main digital information (recorded data), specifies sub digital information,
This is a circuit for performing control for recording sub-digital information. FIG. 3 is a block diagram showing a detailed configuration of the formatter 1. The formatter 1 includes a modulator 1a that modulates recording data input to the apparatus 100 into a signal (channel signal B) suitable for the DVD 9, and a pseudo random number generator 2
And a secret key storage unit 1c for preliminarily storing a 56-bit secret key in advance.

As shown in the timing chart of FIG. 2, the modulation section 1a converts the input recording data into a corresponding 16-bit channel code A for each 8-bit code (byte) (8 to 16 conversion). ), Then NRZ
A channel signal B is generated by I-conversion and output to the phase modulator 6. Also, when receiving a notification from a controller or the like (not shown) that the recording of the secret key (hereinafter, such an operation is referred to as “secret key recording mode”) is started, the modulation unit 1 a Every time the recording data is input, a timing signal indicating the head of the byte is output to the timing generator 3.

When the secret key recording mode is started, the initial value storage section 1b outputs the 15-bit data (initial value) held in secret to the pseudo random number generator 2 in advance.
When the secret key recording mode is started, the secret key storage unit 1c stores the secret key having a 56-bit length, which has been kept secret in advance, in L.
The data is output to the exclusive OR gate 4 in the NRZ format in order of 1 bit from the SB. At this time, the secret key storage unit 1c outputs the next higher-order bit every time the modulator 1a modulates 256 bytes of recording data. That is, the secret key storage unit 1c outputs one 56-bit secret key to the XOR 4 as a secret key bit sequence in correspondence with a total of 256 × 56 bytes of recording data.

FIG. 4 is a diagram showing the correspondence between a secret key, a pseudo-random number sequence, and recorded data. In order to record a 56-bit secret key as hidden information on an optical disk, a 256-bit pseudo-random number sequence is used for each bit of the secret key, and each bit in the pseudo-random number sequence is 1-byte recording data (a 16-bit channel). Code). Each bit of the 56-bit secret key is used as a flag as to whether or not to logically invert the corresponding 256-bit pseudo-random number sequence, as described later.

The timing generator 3 comprises (i) a modulating unit 1a
And outputs a clock signal (byte clock) synchronized with each byte of the recording data to the pseudo-random number generator 2 based on the timing signal from the CPU, and (ii) the timing signal and a clock signal from a clock oscillator (not shown). Based on the above, a timing signal indicating the center of the channel signal B output from the formatter 1 (when the phase becomes 180 degrees) is output to the PE modulator 5.

The pseudo-random number generator 2 uses the initial value from the initial value storage unit 1b as a preset value and the byte clock input from the timing generator 3 as a shift clock.
A pseudo-random number sequence (M-sequence) in which 2 15 bit sequences are defined as one cycle is generated. FIG. 5 shows a pseudo random number generator 2
FIG. 3 is a circuit diagram showing a detailed configuration of FIG. Pseudo random number generator 2
Is a 15-bit length preset register 2a for holding the initial value from the initial value storage unit 1b, a 15-stage (bit) shift register 2b, and the MS of the shift register 2b.
B (the 14th digit) and an exclusive OR gate 2c for calculating the exclusive OR of the output values of the 10th digit.

When the initial value sent from the initial value storage section 1b is set in the preset register 2a, the initial value is written into the shift register 2b by the strobe signal sent from the formatter 1 immediately after that. . Thereafter, in synchronization with the byte clock from the timing generator 3, the 15-bit value stored in the shift register 2b is shifted to the left, and the output value from the exclusive OR gate 2c is shifted to the shift register 2b. LSB
(0th digit) and stored. As a result, a new random number of 1 bit is generated for each byte in the MSB of the shift register 2b and sent to the exclusive OR gate 4 as a pseudo random number sequence.

In the first embodiment, the pseudo random number generator 2 has a total of 256 in the secret key recording mode.
It is used to generate a pseudo-random number sequence embedded in recording data of × 56 bytes, that is, a pseudo-random number sequence of 256 × 56 bits. The exclusive OR gate 4 calculates the exclusive OR of the pseudo random number sequence from the pseudo random number generator 2 and the bit sequence from the secret key storage unit 1c, and converts the resulting pseudo random number sequence D to a PE modulator. 5 is output. That is,
The exclusive OR gate 4 generates 2 bits generated from the pseudorandom number generator 2 according to each bit value of the 56-bit secret key.
Whether the pseudo-random number sequence of 56 bits is directly input to the PE modulator 5 or is input to the PE modulator 5 after logical inversion is selectively performed.

The PE modulator 5 performs PE conversion on the pseudo-random number sequence D sent from the exclusive OR gate 4 based on the timing signal from the timing generator 3, and converts the obtained PE modulation signal E into a phase. Output to the modulator 6. as a result,
As shown in the timing chart of FIG. 2, when the pseudorandom number D output from the exclusive OR gate 4 is 0, the PE modulation signal E falls at the center of the channel signal B, and the pseudorandom number D becomes 1 In this case, the waveform rises, and when the same random number value continues, the waveform is inverted again at the boundary of the channel signal B.

The phase modulator 6 receives the PE signal from the PE modulator 5.
Based on the modulation signal E, phase modulation is performed to delay or advance the edge of the channel signal B from the formatter 1 by a predetermined minute time, and the obtained modulated channel signal F
Is output to the recording channel 7. In addition, the above minute time,
A normal DV in which only the main digital information is recorded by bypassing the phase modulator 6 (without recording the sub digital information)
D9 is preset to a value (0.5σ) that is half the standard deviation σ in the frequency distribution (variation) of the jitter observed when the data is reproduced by a normal reproducing apparatus.

FIG. 6 is a block diagram showing a detailed configuration of the phase modulator 6. The phase modulator 6 includes a delay unit 6a for delaying a signal by the above-mentioned minute time and a selector 6b having two inputs and one output. The selector 6b allows the channel signal B directly input from the formatter 1 to pass when the PE modulation signal E input as the control signal is “1”, and the delay unit 6b when the PE modulation signal E is “0”.
The channel signal B input through a is passed.

Accordingly, the rising and falling edges of the channel signal B input to the phase modulator 6 are:
As a result (in a relative time relationship), when the PE modulation signal E indicates "1" (0 to 180 degrees), the phase is advanced by the minute time, and the PE modulation signal E changes to "0". In the case shown (180 to 360 degrees), the phase is delayed by the minute time. That is, the phase modulator 6
Is subjected to jitter modulation based on a pseudo-random number sequence D, and is converted into a modulated channel signal F as shown in FIG.

The recording channel 7 generates a control signal for turning on / off a laser beam to be exposed on the DVD 9 in synchronization with 1/0 of the modulated channel signal F from the phase modulator 6 and sends it to the recording head 8. The recording head 8 turns on / off the laser beam based on a control signal from the recording channel.
Cutting is performed by applying a beam spot spirally to the surface of the rotating DVD 9 while turning it off. In this manner, the modulated recording mark G composed of optically readable concave or convex pits is
Formed.

FIG. 7 is an external view showing the surface of the recording film of the DVD 9 on which pits have been formed by the recording head 8.
The position of each of the two edges in the track direction of the pit formed in the secret key recording mode is different from the edge position of the pit formed in the case of not the secret key recording mode by a displacement amount corresponding to the above-mentioned fixed minute time. The phase is formed to be shifted to a position where the phase is advanced (or delayed).

FIG. 8 is a graph showing the frequency distribution of the pits formed in such a secret key recording mode, that is, the jitter observed with respect to the modulated recording mark G recorded under the jitter modulation. is there. Curve 121 is
The jitter distribution is shown only for the edge of the modulated recording mark G generated when the PE modulation signal E is "0", and the position X (L) shifted in the direction in which the phase is delayed by the displacement amount is the maximum frequency. It becomes a curve close to a Gaussian curve. Curve 12
Reference numeral 2 denotes a jitter distribution for only the edge of the modulated recording mark G generated when the PE modulation signal E is "1", and a position X shifted in a direction in which the phase is advanced by the displacement amount.
It becomes a curve close to a Gaussian curve with (H) being the maximum frequency.
A curve 123 indicates the entire jitter distribution obtained by adding the curves 121 and 122 together.

According to the present invention, if synchronous detection is performed using the same pseudo-random number sequence as that used when recording the secret key, the jitter distribution of the curve 123 is changed to the curves 121 and 122.
It utilizes that it can be separated into each distribution. As described above, the DVD in which the 56-bit secret key is embedded by the device 100 has the following properties.

The secret key is recorded by jitter modulation in which the position of the edge of the recording mark (each of the two edges in the track direction) is shifted by a very small amount in the track traveling direction (scanning direction of the beam spot). The secret key cannot be read by an ordinary playback device that does not have a function of reading information buried in the device.

Therefore, even if the entire contents of the DVD on which such a secret key is recorded are read out as it is using an ordinary reproducing apparatus and then recorded on another DVD, only the original main digital information is copied. Thus, the sub-digital information (secret key) recorded buried in the jitter is not copied. With this, the original DV
D and illegally copied DVDs can be distinguished. For example, by providing a mechanism in a playback device that permits only playback of a DVD including a secret key,
Copyright infringement due to the distribution of pirated DVDs can be avoided.

The apparatus 100 does not record the 56-bit secret key as it is on the DVD, but associates each bit of the secret key with a 256-bit random number sequence and records the random number sequence on the DVD. . In other words, the information buried in the jitter is not a bit sequence of the secret key but a random number sequence that is kept secret. Therefore, it is difficult to decipher the information and the concealment of the information becomes high.

Further, the present apparatus 100 does not directly modulate the channel signal B with a random number sequence but performs jitter modulation.
Since the channel signal B is jitter-modulated by the PE modulation signal E obtained by once performing the PE conversion of the random number sequence, the modulation for advancing the phase and the modulation for delaying the phase for each 1-byte recording data (one channel code). Are performed with equal establishment (180 degrees each), and during reproduction, stable clock extraction and reproduction are performed.

That is, if the edge phase is advanced first
If only the second state or the second state to be delayed continues for a long time, a PLL (Phas
e Locked Loop) follows the biased edge position after the phase modulation, and the phase error signal disappears, so that the detection sensitivity of the phase modulation component decreases. However, in the present apparatus 100, such a problem is avoided because the jitter modulation is performed on the PE modulation signal E. [Optical Disk Reproducing Apparatus] Next, a reproducing apparatus corresponding to a DVD in which a secret key is recorded as described above will be described.

FIG. 9 is a block diagram showing a configuration of a characteristic portion of the optical disk reproducing apparatus 110 according to the present invention. The waveforms of the main signals H and I shown in this figure are as shown in the timing chart of FIG.
The present device 110 is a DVD reproducing device corresponding to the optical disk recording device 100, and not only reproduces the main digital information based on the position of the recording mark on the DVD, but also reduces the jitter of the recording mark observed at that time. It has a function of detecting buried sub-digital information (secret key) and performing an operation for protecting copyright based on the detection result, and includes a reproducing head 11, a reproducing channel 12, and a reproducing signal processing circuit 1.
3, clock extractor 14, synchronous detector 15, verification unit 16
And a pseudo random number generator 17.

The reproducing head 11 is an optical pickup, which condenses and irradiates a recording mark on the rotating DVD 9 with a light beam, and uses the reflected light to read an analog read signal indicating the edge position of the modulated recording mark G. Is generated and output to the reproduction channel 12. The reproduction channel 12 converts the analog read signal from the reproduction head 11 into a digital read signal by equalizing or shaping the waveform, and converts the analog read signal into a reproduction signal processing circuit 13 and a clock extractor 14.
Output to

The clock extractor 14 is connected to the reproduction channel 12
, Four types of clock signals, i.e., (i) a channel bit clock synchronized with each bit constituting the channel code, and (ii) the advance of the read signal based on the channel bit clock. A phase error signal H indicating only the component, (iii) a delay error signal I indicating only the lag component, and (iv) a byte clock synchronized with each recording data (byte unit) in the read signal. And generate, respectively, (i)
Reproduction signal processing circuit 13, (ii) synchronous detector 15, (ii)
i) output to the synchronous detector 15, (iv) the reproduction signal processing circuit 13, the synchronous detector 15, and the pseudorandom number generator 17.

FIG. 10 is a block diagram showing a detailed configuration of the clock extractor 14. The clock extractor 14 includes a phase comparator 14a, a loop filter 14b, and a VCO (Vo).
PLL consisting of ltage Controlled Oscillator) 14c
Circuit, 4-bit counter 14d, and synchronization signal detector 1
4e and a phase error signal separator 14f.

The phase comparator 14a comprises a counter, an exclusive OR gate, a flip-flop, etc.
From the channel bit clock fed back from 4c and the read signal from the reproduction channel 12, the phase difference between the rising and falling edges of the read signal and the rising edge of the channel bit clock closest to the edge is calculated. A loop filter 14b and a phase error signal separator 14f as phase error signals.
Output to

The loop filter 14b includes a phase comparator 14
This is a low-pass filter that smoothes the phase error signal from a and converts it into a DC voltage signal. The VCO 14c is a voltage controlled oscillator that generates a channel bit clock having a frequency corresponding to the voltage signal from the loop filter 14b. The synchronization signal detector 14e detects a synchronization pattern included in the read signal and outputs the same to the 4-bit counter 14d as a reset signal. The 4-bit counter 14d is
Channel bit clock from VCO 14c is 1/16
Is reset by a reset signal from the synchronization signal detector 14e. That is, the 4-bit counter 14d outputs a byte clock synchronized with each recording data (byte unit) in the read signal.

The phase error signal separator 14f is a circuit that separates the phase error signal from the phase comparator 14a into a phase error signal H and a phase error signal I and outputs the separated signal to the synchronous detector 15. FIG. 11 is a circuit diagram showing a detailed configuration of the phase error signal separator 14f. The phase error signal separator 14f
Inverters 30a, b and two AND gates 30
c and d.

FIG. 12 is a timing chart of each signal for explaining the operation of the phase error signal separator 14f shown in FIG. The phase error signal output from the phase comparator 14a includes a leading phase error component and a lagging error component. Since these phase error signals H and I are separated in synchronization with the channel bit clock, a logical product The signal (leading error signal H) output from the gate 30c shows only the leading error component, and the signal (lagging error signal I) output from the AND gate 30d has a waveform showing only the delay error component. .

The reproduction signal processing circuit 13 includes a reproduction channel 1
2 is a circuit for demodulating the readout signal from the second digital signal, controlling the detection of the sub-digital information, and performing the operation for protecting the copyright based on the detection result. FIG. 13 is a block diagram showing a detailed configuration of the reproduction signal processing circuit 13. The reproduction signal processing circuit 13 includes a demodulation unit 13a, an output gate 13b, and an initial value storage unit 13c.

The demodulation unit 13a is provided in the optical disk recording device 10
0 is a demodulation circuit corresponding to the modulating unit 1a, which demodulates to a channel code A by sampling a read signal from the reproduction channel 12 in synchronization with a channel bit clock from the clock extractor 14, Is converted to 8-bit recording data corresponding to each channel code in synchronization with the byte clock from (16 to 8).
Conversion), and sends the recording data sequence to the output gate 13b.

The output gate 13b is a buffer gate for copyright protection, and receives an enable signal from the verification unit 16 (notification that the proper secret key has been recorded on the DVD 9). Only while the demodulator 1
The recording data stream from 3a is passed and output to the outside as a reproduction signal. The initial value storage unit 13c is a register that secretly stores the same value (15-bit initial value) as the initial value storage unit 1b of the optical disk recording device 100 in advance in secret, and reads out a secret key (hereinafter, such an operation is referred to as “ When a notification that the “private key read mode” has been started is received from a controller (not shown), the initial value is output to the pseudo random number generator 17.

The pseudo-random number generator 17 has the same function as the pseudo-random number generator 2 of the optical disc recording apparatus 100, sets the initial value from the initial value storage section 1b as a preset value, and inputs the preset value from the clock extractor 14. Using the byte clock as a shift clock, a pseudo-random number sequence (M sequence) having 2 15 bit sequences as one cycle is generated. This device 11
0 is used to generate a 256 × 56 bit pseudo-random number sequence.

The synchronous detector 15 is a circuit for detecting the correlation between the phase error signal H and the phase error signal I output from the clock extractor 14 and the pseudorandom number sequence from the pseudorandom number generator 17. Yes, the result (positive correlation, negative correlation, no correlation) of each pseudo random number (1 bit) is transmitted to the verification unit 16. FIG. 14 is a circuit diagram showing a detailed configuration of the synchronous detector 15. The synchronous detector 15 includes a PE modulator 15a, a selector 15b, an integrator 15c, a threshold value determination unit 15d, and an 8-bit counter 15e.

The PE modulator 15a is a modulator having both functions corresponding to the timing generator 3 and the PE modulator 5 of the optical disk recording apparatus 100, and a pseudo random number generator based on the byte clock from the clock extractor 14. 1
7 is subjected to PE conversion and output to the selector 15b as a switching control signal. That is, if the pseudorandom number from the pseudorandom number generator 17 is 0, it falls at the center timing of each recording data (byte) in the reproduced read signal, and if the pseudorandom number is 1, it rises and has the same random number value. Continues, a signal having a waveform that is inverted once again at the boundary of each recording data is selected by the selector 15.
b.

The selector 15b is composed of two two-input one-output switching circuits, and converts each of the leading error signal H and the lag error signal I from the clock extractor 14 into a PE modulator 15a.
When the control signal is "1", the signal is passed through the positive input terminal and the negative input terminal of the integrator 15c. When the control signal is "0", the signal is crossed and passed through the negative input terminal and the positive input terminal of the integrator 15c.

The 8-bit counter 15e is a counter that divides the byte clock from the clock extractor 14 by 1/256, and uses the result as a reset signal as an integrator 1e.
5c, output to the threshold determination unit 15d and the verification unit 16. Therefore, this reset signal is output from the pseudo random number generator 17.
Is a waveform that outputs one reset pulse every time a 256-bit random number sequence is output.

The integrator 15c is a differential input bipolar output analog integrator. The integrator 15c adds and accumulates the area of the pulse input to the positive input terminal and simultaneously outputs the pulse input to the negative input terminal. , And accumulates the analog signal corresponding to the accumulated total area.
Output to 5d. At this time, when a reset signal is input from the 8-bit counter, the data is accumulated from zero again.

As a result, the output waveform of the integrator 15c is such that the PE modulation signal output from the PE modulator 15a is 1
In the period, the area of the pulse appearing in the phase error signal H is added and accumulated, and the area of the pulse appearing in the phase error signal I is subtracted and accumulated. In the figure, the accumulated area is obtained by subtracting and accumulating the area of the pulse appearing in the phase error signal H and adding and accumulating the area of the pulse appearing in the delay error signal I.

Therefore, a positive correlation in which a pulse appears only in the phase error signal H during the period when the PE modulation signal is 1 and a pulse appears only in the phase error signal I during the period when the PE modulation signal is 0 is obtained. Is continued, the integrator 15c
Is a ramp waveform that increases in the positive direction. Conversely, a pulse appears only in the delay error signal I during the period when the PE modulation signal is 1, and the phase error increases during the period when the PE modulation signal is 0. When a negative correlation in which a pulse appears only in the signal H continues, the output waveform of the integrator 15c becomes a ramp waveform that decreases in the negative direction. In addition, when no correlation exists, that is, the phase error signal H and the phase error signal I are randomly determined without depending on the value of the PE modulation signal.
, The frequencies of the two pulses appearing in the error signal are substantially equal, so that the output waveform of the integrator 15c maintains a value close to zero level.

The threshold value judging section 15d judges which of three voltage sections the analog signal from the integrator 15c is divided by a predetermined positive threshold voltage and a predetermined negative threshold voltage. And the like. FIG.
Is a diagram for explaining the operation of the threshold value determining unit 15d, and shows an example of an analog signal waveform input from the integrator 15c to the threshold value determining unit 15d. Threshold judgment unit 15
d is set to 1 when the reset signal is input from the 8-bit counter 15e (immediately before), (i) when the signal voltage from the integrator 15c is larger than the positive threshold, and is set to 1; If smaller, the NRZ format code string that is set to 0 is output to the verification unit 16, and
(Ii) If the signal voltage from the integrator 15c falls between the two threshold values, the verification unit 16 is notified of a violence signal indicating that fact.

It should be noted that the threshold voltage certainly exceeds (with a very high probability) when the jitter modulation according to the present invention is performed, but does not exceed (with a very high probability) otherwise. The output voltage value of the integrator 15c is set to (low), and the specific value is input to the integrator 15c and the jitter modulation degree during recording (the delay amount of the delay unit 6a of the phase modulator 6). Number of bytes (256),
It is determined by the average number of edges per byte, the standard deviation in the natural (randomly occurring) jitter distribution, and the like.

As described above, the code string output from the threshold value judging unit 15d indicates a change in the polarity (positive or negative) of the correlation observed for each 256-bit pseudorandom number. Such a change in polarity is information corresponding to a bit string indicating, for each 256-bit pseudo-random number sequence, whether the pseudo-random number sequence was recorded by jitter modulation without logical inversion or recorded after logical inversion.

The verifying section 16 converts the DVD 9 that has been read out into the normal optical disk recording apparatus 1 based on the code string and the violence signal sent from the synchronous detector 15.
Then, it verifies whether or not the medium is a medium recorded by 00, and outputs an enable signal to that effect to the reproduction signal processing circuit 13 only when it can be positively determined. FIG. 16 is a block diagram illustrating a detailed configuration of the verification unit 16. The verification unit 16 includes a secret key storage unit 16a, a shift register 16b,
It comprises a coincidence comparing section 16c and an output latch section 16d.

The secret key storage section 16a is a register for previously storing the same 56-bit secret key as the secret key storage section 1c of the optical disk recording device 100. Shift register 16
Reference numeral b denotes a 56-stage (bit) shift register that stores the code string from the synchronous detector 15 while shifting it using the reset signal from the clock extractor 14 as a shift clock.

The coincidence comparator 16c is provided with a shift register 16
Immediately after the 56-bit code string is input to b, whether or not the code string completely matches the 56-bit secret key held in the secret key storage unit 16a is compared. Notify section 16d. Output latch section 16
d outputs an enable signal to the reproduction signal processing circuit 13 only when no notification of a violence signal is received from the synchronous detector 15 and a notification of a complete match is sent from the match comparison unit 16c. That is, the pseudo random number generator 17
56 times (2) that there is a positive or negative correlation between the 256-bit pseudo-random number sequence input to the synchronous detector 15 and the phase error signal included in the readout signal.
56 × 56 bit pseudo-random sequence)
The change in the polarity of the correlation at that time is determined by the secret key storage unit 1.
Only when it matches the 56-bit secret key stored in the reproduction signal processing circuit 13
Output an enable signal.

In this way, the secret key reading mode is completed, and at this time, when the enable signal is output from the verification unit 16 to the reproduction signal processing circuit 13,
The DVD 9 is determined to be a medium in which a secret key is embedded by the authorized optical disk recording device 100, and the reproduction signal processing circuit 13 outputs a reproduction signal obtained by demodulating a read signal from the reproduction channel 12 to the outside. . on the other hand,
When the enable signal is not output from the verification unit 16 to the reproduction signal processing circuit 13, it is determined that the DVD 9 is not a medium in which the secret key is embedded by the authorized optical disk recording device 100, and the reproduction signal processing circuit 13 In order to protect the copyright, the reproduction signal is not output to the outside.

As a result, it is possible to prevent the recorded data from being illegally read from the DVD 9 in which the embedding of the secret key cannot be confirmed. Therefore, by duplicating a regular DVD including a secret key, a new D
Even if the VD is created, unless the secret key embedded by jitter modulation is copied together, the DVD
Is prohibited from being played by the device 110,
Copyright is protected. (Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. [Optical Disk Recording Apparatus] FIG. 17 is a block diagram showing a configuration of a characteristic portion of an optical disk recording apparatus 200 according to the present invention. Note that the waveforms of the main signals B, D, and E shown in this figure are as shown in the timing chart of FIG. A block surrounded by a double line indicates that the component is implemented in a secret state.

The present apparatus 200 not only records main digital information by forming recording marks at discrete reference positions on tracks of an optical disc, but also records the positions of the recording marks at that time in the radial direction of the DVD 9. (At least one of the peripheral side and the outer peripheral side)
Forming a recording mark by shifting the position in the radial direction is called "radial modulation". ) To obtain hidden information such as a watermark (in this case, a 56-bit secret key).
Is a recording device for a DVD-ROM having a function of simultaneously recording while embedding in the main digital information as sub-digital information. The formatter 1, the pseudo-random number generator 2,
It includes a timing generator 3, an exclusive OR gate 4, a PE modulator 5, a radial modulator 18, a tracking actuator 19, a recording channel 7, and a recording head 8.

The same components as those in the first embodiment are denoted by the same reference numerals. Hereinafter, a description will be given focusing on a point different from the first embodiment. The radial modulator 18 generates a signal for displacing the recording head 8 to the inner side or the outer side of the DVD 9 by a certain minute amount based on the PE modulation signal E from the PE modulator 5 (radial modulation is performed). And outputs it to the tracking actuator 19. As a result, the recording mark formed in synchronization with the channel signal B is cut at a position displaced from the center of the track of the DVD 9 to the inner peripheral side or the outer peripheral side by a certain minute amount.

The minute amount is a radial error observed when a normal DVD 9 on which only main digital information is recorded is subjected to push-pull reproduction by a normal reproducing apparatus (from the center of the pit forming position in the radial direction to the track center). Is set in advance (that is, so as to fluctuate with an amplitude equal to or less than the noise amplitude). In particular,
The wavelength of the laser beam of the recording head 8 is set to λ (for example, 0.
65 μm), and the numerical aperture of the lens is NA (for example, 0.6).
Is set to a value (for example, 0.01 μm) of 2% or less of the beam spot determined by λ / NA.

When the PE modulation signal E indicates "1", the radial modulator 18 displaces the recording head 8 inward by a small amount with respect to the center of the track,
When the E modulation signal E indicates "0", the signal is displaced toward the outer peripheral side by the minute amount. In the first embodiment, the phase modulator 6 shifts the position of each of the two edges that determine the length of the recording mark, whereas in the second embodiment, the radial modulator 18 The position of the recording mark (in other words, the positions of the two edges that determine the width of the recording mark) is shifted in the radial direction, and the sub digital information is recorded.

The recording channel 7 is 1/1 of the channel signal B.
The laser beam for exposing the DVD 9 in synchronization with 0
A control signal for N / OFF is generated and sent to the recording head 8. The recording head 8 receives a control signal from a recording channel and a tracking actuator 19 from the radial modulator 18.
ON / OF the laser beam based on the drive signal to
The cutting is performed by irradiating a beam spot spirally on the surface of the rotating DVD 9 while displacing it by a small amount in the radial direction at the same time as performing F.

In this way, as shown in the timing chart of FIG. 18, the modulated recording mark F composed of optically readable concave or convex pits is formed on the DVD 9. As can be seen by comparing the standard recording mark C and the modulated recording mark F shown in FIG. 18, the modulated recording mark F formed by the optical disc recording apparatus 200 is a part of the normal standard recording mark C. Or all of them are equivalent to those displaced in the radial direction.

FIG. 19 shows the state of the surface of the DVD 9 recording film on which such pits (recording marks) are formed.
The position in the radial direction of the pit formed in the secret key recording mode is shifted from the position of the pit formed in the non-secret key recording mode by an amount corresponding to the minute amount described above on the inner peripheral side (or outer peripheral side). It is shifted. In addition,
As described above, the very small amount is an amount buried in noise observed during reproduction, and actually, pits are not formed at positions significantly shifted as shown in FIG. That is, the shape of the modulated recording mark F and the waveform of the radial error signal G shown in FIG. 18 and the shape and displacement of the pits shown in FIG. 19 are exaggerated as compared with actual ones.

FIG. 20 is a graph showing the frequency (frequency) distribution of radial errors observed for the pits formed in such a secret key recording mode, that is, for the modulated recording mark F recorded by receiving the radial modulation. It is. A curve 221 shows a radial error distribution (variation) of only the modulated recording mark F generated when the PE modulation signal E is “0”, and the position X (L) shifted to the inner peripheral side by the displacement amount. Becomes a curve close to a Gaussian curve having the maximum frequency. A curve 222 indicates a radial error distribution only for the modulated recording mark F generated when the PE modulation signal E is “1”, and the position X (H) shifted to the outer peripheral side by the displacement amount is defined as the maximum frequency. It becomes a curve close to a Gaussian curve. A curve 223 shows the entire radial error distribution obtained by adding the curves 221 and 222 together.

According to the present invention, if synchronous detection is performed with the same pseudo-random number sequence as that used when recording the secret key, the radial error distribution of the curve 223 is changed to the curve 221 as in the first embodiment. The fact that the curve 222 can be separated into distributions is used. As described above, this device 2
DVD with 56-bit secret key embedded by 00
Has the following properties:

Since the secret key is recorded by radial modulation in which the position of the recording mark is shifted by a very small amount in the direction (radial direction) orthogonal to the track traveling direction, simply detecting the push-pull is buried in noise. An ordinary reproducing apparatus which does not have a function of reading the information cannot read the secret key. Therefore, even if the entire contents of the DVD on which such a secret key is recorded are read out as-is using an ordinary reproducing device and then recorded on another DVD, only the original main digital information is copied, and The sub-digital information (secret key) buried and recorded in the file is not copied. This makes it possible to distinguish the original DVD from the illegally copied DVD. For example, by providing a playback device with a mechanism that permits only playback of a DVD containing a secret key, Copyright infringement due to the distribution of DVDs can be avoided.

Further, the present apparatus 200 does not record the 56-bit secret key as it is on the DVD, but associates each bit of the secret key with a 256-bit random number sequence and records the random number sequence on the DVD. . That is, the information buried in the noise is not a bit sequence of a secret key but a secret random number sequence, so that it is difficult to decipher the information and the information is highly concealed.

Further, the present apparatus 200 does not directly modulate the recording mark corresponding to the channel signal B with the random number sequence, but instead converts the channel signal with the PE modulation signal E obtained by once performing the PE conversion of the random number sequence. Since the recording mark corresponding to B is radially modulated, the modulation (1) for displacing the recording mark inward and the modulation for displacing the recording mark outward (for each one-byte recording data (one channel code)) 0) is performed with equal probability, and stable push-pull detection is performed during reproduction.

In other words, if both displacements do not occur at the same establishment, an offset occurs in the push-pull signal (usually used for tracking servo detection), and consequently servo is applied to a position shifted from the tracking center. . Further, when servo is applied to a position shifted from the tracking center, the amplitude of the radial error signal (a signal indicating the amount of shift of the position of the recording mark from the track center in the radial direction) decreases, and the detection sensitivity of the radial modulation component decreases. Will drop. However, in the present apparatus 200, such a problem is avoided because the PE modulation signal E performs the radial modulation.

In the second embodiment, the PE modulator 5 is used to generate the displacement in the radial direction. However, PE (Phase Encoding) means that the displacement in the phase, that is, the jitter direction is applied in the first place. However, this does not originally mean providing a displacement in the radial direction perpendicular to the jitter direction as in the second embodiment. However, in the second embodiment, the displacement in the radial direction can be realized using a circuit having the same configuration as the PE modulator 5 used in the first embodiment. It is explained using the same language.

Further, the first optical disk recording apparatus of the present invention
In the second embodiment, the PE modulation signal is “0”.
Although it is described that the value takes a binary value of "1" and "1", "0" of the PE modulation signal does not include a case where PE modulation is not applied, that is, a case where copyright protection information is not inserted. That is,
If you want to create a track without copyright protection information,
It is necessary to prevent the pit edge from being displaced in the jitter direction or the radial direction at all, and a third value (for example, “Z”) is required. [Optical Disk Reproducing Apparatus] Next, a reproducing apparatus corresponding to a DVD in which a secret key is recorded as described above will be described.

FIG. 21 is a block diagram showing a configuration of a characteristic portion of the optical disk reproducing apparatus 210 according to the present invention. Note that the radial error signal G shown in FIG.
Is conceptually as shown in the timing chart of FIG. However, as described above, since the radial error signal G is actually buried in noise, it is not detected remarkably like the waveform shown in FIG.

The present apparatus 210 is a DVD reproducing apparatus corresponding to the above-mentioned optical disk recording apparatus 200, and reproduces not only the main digital information based on the position of the recording mark in the track direction on the DVD, but also observes at that time. The sub-digital information (secret key) buried in the noise of the radial error signal and performing an operation for protecting the copyright based on the detection result.
1, a reproduction channel 12, a reproduction signal processing circuit 13, a clock extractor 14, a synchronous detector 15, a verification unit 16, a pseudorandom number generator 17, and a radial error detector 20.

The reproducing head 11 is an optical pickup, which focuses and irradiates a recording mark on the rotating DVD 9 with a light beam, and displaces the modulated recording mark F from the track center in the radial direction from the reflected light. A radial error signal G indicating the amount is generated to generate a radial error signal G.
Output to 0. FIG. 22 is a block diagram showing a detailed configuration of a portion of the reproducing head 11 related to the generation of the radial error signal G. In the reproducing head 11, the light beam emitted from the semiconductor laser 11a is converted into parallel light by the optical system 11b. After passing through the objective lens 11d, the light beam is condensed as a light beam spot and irradiated on the DVD 9.

The reflected light reflected and diffracted in the radial direction by the DVD 9 passes through the objective lens 11d, becomes parallel light, is separated from the incident light in the optical system 11b, and is divided into two.
Irradiating the three photodetectors 11e, and the modulated recording mark F
Are converted into two electric signals indicating the inner and outer displacement amounts of the inner and outer circumferences. The two electric signals are input to the differential calculator 11f, become a radial error signal G indicating the difference between the two displacement amounts indicated by the electric signals, and output to the radial error detector 20.

The radial error detector 20 is a demodulator corresponding to the radial modulator 18 included in the optical disk recording apparatus 200. The radial error detector 20 receives a digital read signal from the reproduction channel 12 as a synchronization signal and sends it from the reproduction head 11. From the received radial error signal G, an inner-peripheral-side displacement signal H and an outer-peripheral-side displacement signal I indicating whether the recording position of the modulated recording mark F is displaced from the center of the track to the inner peripheral side or the outer peripheral side in the radial direction. Is demodulated, and the synchronous detector 15 is demodulated.
Output to Here, if there is no normal noise (radial error when no radial modulation is performed), the inner peripheral side displacement signal H and the outer peripheral side displacement signal I are respectively shown in the timing chart of FIG. As described above, the logic signal indicates a portion (part or the whole) of the modulated recording mark that is shifted from the center of the track toward the inner circumference and the outer circumference.

FIG. 23 is a block diagram showing a detailed configuration of the radial error detector 20. The radial error detector 20 includes an LPF (low-pass filter) 20a, two comparators 20b and 20c, and two output gates 20.
d, 20e, and a DC component extraction unit 20f.
The DC component extraction unit 20f extracts a DC component indicating the track center from the radial error signal G output from the reproducing head 11, and based on the extracted DC component, the comparator 20b,
Generate two reference voltages (± V) to create a comparison reference voltage to 20c.

After the high-frequency noise is cut off by the LPF 20a, the radial error signal G input to the radial error detector 20 is divided into two comparators 20b,
20c, and it is determined whether or not the amplitude exceeds two positive and negative comparison reference voltages. Comparator 20b, 2
The comparison reference voltage of 0c is a threshold value for determining that the recording position of the modulated recording mark F is significantly displaced from the track center to the inner side or the outer side, for example, ± 0.005 μm from the track center. Is set to a voltage corresponding to the position shifted by only Thereby, for example, the position of the recording mark is shifted from the track center by the above-mentioned minute amount (± 0.01 μm).
m) is detected.

The output gates 20d and 20e are gates that allow the outputs of the comparators 20b and 20c to pass only during the time when the modulated recording mark F is detected by the reproduction channel 12. The clock extractor 14 in the present apparatus 210 performs two types of clock signals based on the read signal from the reproduction channel 12, (i) a channel bit clock synchronized with each bit constituting a channel code,
(Ii) A byte clock synchronized with each recording data (byte unit) in the read signal is extracted and generated, and (i) the reproduced signal processing circuit 13, (ii) the reproduced signal processing circuit 13, the synchronous detector 15, and Output to the pseudo random number generator 17.

Reproduction signal processing circuit 13, pseudo random number generator 1
7. The synchronous detector 15 and the verification unit 16 are circuits having the functions described in the first embodiment. Synchronous detector 15
Is a circuit for detecting the correlation between the inner displacement signal H and the outer displacement signal I output from the radial error detector 20 and the pseudorandom number sequence from the pseudorandom number generator 17. The result (with positive correlation, with negative correlation, without correlation) of each (1 bit) is transmitted to the verification unit 16.

In the first embodiment, the sub-digital information (key information) is embedded as a displacement of the edge position in the track direction of the recording mark by phase modulation, whereas in the second embodiment, the radial information is Since the modulation is embedded as a displacement of the recording mark in the radial direction of the recording mark by the modulation, the phase error signals (leading error signal and lagging error signal) in the first embodiment are
Assuming that it corresponds to the radial error signal (inner peripheral side displacement signal and outer peripheral side displacement signal) in the second embodiment, a copyright protection system similar to that of the first embodiment is realized.

One of the advantages of the second embodiment as compared with the first embodiment is that almost the same functions can be realized at lower cost using lower-speed circuits. That is, in the first embodiment, these circuits need to operate at least at the channel clock rate, as can be seen from the operation of the phase error signal separator 14f and the like for detecting the amount of jitter fluctuation. High accuracy is required in the time axis direction.

On the other hand, in the second embodiment, as can be seen from the fact that the differential operation unit 11f and the radial error detector 20 which are merely modifications of the differential amplifier are used instead of these, these circuits are used. Suffices to operate at the frequency of appearance of the modulated recording mark F, that is, the rate of the channel signal. As described above, the recording medium and the recording / reproducing apparatus relating to the jitter modulation and the radial modulation of the present invention have been described based on the first and second embodiments. However, the present invention is not limited to these embodiments. Of course.

For example, in the first and second embodiments,
2 logically inverted corresponding to one 56-bit secret key
Although a 56 × 56 bit pseudo-random number sequence is embedded in 56-byte continuous recording data, the present invention is not limited to such numerical values. For a number of bytes related to a physical recording structure such as an ECC block, a sector, a frame, or the like, and a recording data of a specific area, a pseudo random number sequence starting from not only one kind but also two or more kinds of initial values is embedded in a plurality of areas. It can also be a system.

In the first and second embodiments, the positive or negative correlation between the phase error signal and the pseudo-random number sequence is determined every 256 bytes in order to confirm that the DVD 9 is valid. It is assumed that there are 56 consecutive occurrences of, but for example, it may be 50 or more out of 56 times. The distribution of jitter and radial error is shown in FIG.
As shown in FIG. 0, there is a certain degree of spread. Therefore, depending on the number of pulses used for determining the correlation, the degree of jitter modulation, the amount of displacement in the radial direction, and the like, a significant correlation is obtained by a criterion having a certain degree of spread. This is because it may be more appropriate to determine the presence or absence.

In the first and second embodiments, the reproduction of the main digital information is restricted when the coincidence between the code string output from the synchronous detector and the secret key is equal to or less than a predetermined number. Without using a secret key, the phase error signal or displacement signal integrated by the synchronous detector is compared with a predetermined threshold value. If it is determined that the correlation is strong and the reproduction is restricted, a certain effect can be obtained with a simpler configuration.

In the first and second embodiments, in synchronous detection of the phase error signal and the displacement signal, the correlation is determined by integrating the pulse area in an analog manner. However, in order to simplify the circuit, Alternatively, a digital system in which the numbers are simply counted while adding and subtracting them may be used. Further, the jitter modulation and the radial modulation according to the present invention can be applied not only to the recording data recorded in the user information area 9a of the DVD 9, but also to the secret key stored in the control information area 9b. Therefore, it can be used by being superimposed on the above-described conventional content encryption. For example, by performing jitter modulation or radial modulation according to the present invention when recording a disk key or a title key stored in the control information area 9b, the recorded content (digital information) by conventional content encryption is completely changed. Without this, it is possible to enhance copyright protection against unauthorized copying such as piracy.

In the first and second embodiments, the optical disk reproducing apparatus outputs the demodulated reproduced signal only when the existence of the secret key buried in the DVD 9 can be verified. The invention is not limited to such a usage form of the verification result. For example, when the validity of the DVD 9 cannot be verified, a usage form such as allowing reproduction of only the title recorded in a specific area of the DVD 9 may be used.

In the first and second embodiments, the secret key used as the sub-digital information is stored in advance in each of the optical disk recording device 100 and the optical disk reproducing device 110. It may be configured to be rewritten by secret communication with the device.
In the first and second embodiments, the jitter modulation according to the present invention is used for concealing the sub-digital information and embedding it in an optical disc. However, the present invention is limited to such a concealment use. Not something. For example, different types of digital information are recorded in a separable and reproducible state by superimposing audio information (sub-digital information) on image information (main digital information) and writing it on a recording medium, thereby improving the recording density. It may be used for encryption.

In the second embodiment, the tracking actuator 19 is used for radial modulation. Instead of this, an AO (Acoustic Optical) deflecting element is used to change the laser beam in the radial direction. It may be deflected only to the inner peripheral side or the outer peripheral side. (Third Embodiment) Hereinafter, a third embodiment will be described with reference to the drawings.

FIG. 24 is a configuration diagram of an optical disc 311 according to the third embodiment of the present invention. This optical disk 31
1, copy guard information 312 is recorded. In that part, the reference clock is locally phase-modulated, and data is recorded as pits and land rows at the timing of the phase-modulated clock. That is, the optical disk 31
On 1, there is a data string that is partially recorded with an appropriate shift from the reference channel clock. Since that portion is out of phase from the reference clock, when it is reproduced, it is detected as a portion having a large jitter value.

In the third embodiment, the sub-digital information (copy guard information 3) is shifted by shifting the phase of the reference clock within the range observed as jitter during reproduction.
12) is common to the first embodiment in embedding 12), but differs from the second embodiment in that the shift amount is not so small as to be buried in noise. In FIG. 24, an area A indicates a portion recorded by a normal reference clock, and an area B
Represents a portion recorded by a phase-modulated clock. FIG. 25 shows an enlarged view of the portion.

The pits 321 in the area A and the area B in FIG. 25 correspond to the case where a single 3T signal is recorded. Vertical dashed lines indicate reference channel clock timing. The pits in the area A recorded at the reference clock timing have start and end positions of pits and lands.
It is recorded so as to be synchronized with the channel clock timing. On the other hand, at the phase-modulated clock timing, the pits or lands in the recorded area B are formed such that the start or end position has a partial phase error with the rising and falling positions of the channel clock.

As a phase modulation method, for example, FIG.
As shown in (2), there is a method of sequentially adding a predetermined amount of phase shift such as a left edge shift a, an enlargement shift b, a degeneration shift c, and a both edge right shift d. In addition, it is considered that there is a phase shift related to the phase shift of the phase-modulated clock, such as one right shift and one left shift.
A method of phase-modulating a clock signal with random noise defined by a predetermined variance value is also conceivable. In any case, due to these edge shifts in part,
In the area B, the jitter increases, and copy guard information can be added in accordance with the deviation of the jitter value.

FIG. 26 is a block diagram of an optical disk apparatus provided with identification information detecting means for detecting copy guard information from a jitter value. The reproduction signal HF read from the optical disk via the reproduction head is supplied to the comparator 3
The binarized signal PSG is converted to a phase-locked loop (PLL) for generating a system reference clock.
ck loop) circuit 332. Furthermore, P
The LL circuit 332 generates a reproduction clock CK, and the flip-flop 334 thereby synchronizes the binary signal PSG to generate a reproduction signal DAT.

FIG. 27 shows an example of the eye pattern of the reproduction signal HF. According to FIG. 24, an eye pattern having some jitter generated by noise or waveform distortion of a reproduction channel is obtained from a signal reproduced from the area A recorded at the reference clock timing. On the other hand, the phase of the eye is partially shifted from the signal reproduced from the recorded area B at the phase-modulated clock timing, so that the reproduced signal jitter is further increased as compared with the signal in the area A. .

In the PLL circuit 332, the phase comparator 3
Reference numeral 32a compares the phase of the reproduction clock CK output from the voltage-controlled oscillation circuit (VCO) 332c with the reproduction signal HF, and outputs the phase comparison result. Low-pass filter (L
The PF 332b band-limits the phase difference result to generate a phase error signal. Voltage controlled oscillator (VCO) 3
32c is a reproduction clock C according to the phase error signal.
Generate K.

Here, if the fluctuation due to the phase modulation when recording the signal on the optical disk exceeds the tracking operation band of the PLL circuit 332, the clock CK generated by the PLL circuit 332 partially Do not follow the modulated clock. Further, at this time, the phase fluctuation applied on the recording side requires that the average value of the phase error in a period outside the tracking band of the PLL circuit 332 be zero. That is, when phase modulation is performed on the recording side, it is necessary to combine the edge shift patterns shown in FIG. 25 so that the average value of the phase error is 0 in a frequency band where the PLL circuit 332 does not respond. At this time, as shown in FIG. 27, the output signal of the phase comparator 332a that has passed through the LPF 332b has all of its high-frequency components removed, and becomes a flat signal.

As a result, the PLL circuit 332 does not follow the phase-modulated clock and does not shift from the original reference clock. A phase error, ie, jitter occurs. The amplitude detector 333 is a phase comparator 33
A signal corresponding to the amplitude of the output signal of 2a, that is, the amplitude of the phase error signal before passing through the LPF 332b (ie, the absolute value of the phase error) is generated. FIG. 27 shows a waveform of the reproduced signal jitter detection signal JT corresponding to the reproduced signal HF.
Copy guard information can be identified based on the change in the detection signal JT.

As a method of judging whether or not the disc is a law-generated disc, for example, when creating an optical disc,
In the control information area or the like, key information (keyword) having a unique relationship with the copy guard information recorded by the jitter is recorded as ordinary binary information,
At the time of reproduction, there is a method of comparing the keyword obtained from the reproduced data with identification information detected from the fluctuation of the jitter value, and judging that the law is compliant only when there is a correlation.

Hereinafter, the normal information reproduction will be described. As described above, the signal PSG binarized by the comparator 331 is output at the timing of the reproduction clock CK generated by the PLL circuit 332 and is converted into a reproduction signal DAT. FIG. 28 is a timing chart for explaining the operation of the detection device of FIG. The reproduction signal HF is
The signal is converted into a binary signal PSG by the comparator 331. Since the reproduced signal HF partially has a phase shift (jitter), the binary signal PSG also contains jitter. As described above, the PLL circuit that generates a reproduction clock of the system from the binary signal PSG generates the reproduction clock CK that does not follow the phase shift (jitter) and has no phase fluctuation. If the binary signal PSG output from the comparator 331 is latched by the flip-flop 334 with the reproduced clock CK, a reproduced signal DAT containing copy guard information and from which jitter has been removed is generated.

On the other hand, a case in which a disc is illegally copied from a reproduced signal using, for example, the apparatus shown in FIG. 29 will be described. In FIG. 29, first, the rotations of the spindle motors of the optical disk 361 to be copied and the optical disk 362 to be copied are completely synchronized, and the reproduction head 3
The data is read through 63 and a reproduction clock is generated by a PLL circuit 366 through a reproduction amplifier 364 and a comparator 365. At the timing of the reproduction clock, the data read from the optical disk 361 is synchronized and output by the flip-flop 367, passed through the optical modulator 368, and recorded on the optical disk 362 by the recording head 369. According to the conventional method, digitized content can be easily copied with such a device.

However, if the optical disk and the optical disk device of the third embodiment are used, simply copying the reproduced signal will cause the jitter to be described when synchronized by the flip-flop 367 as described above. Since the copy guard information is missing, the copy can be identified as an illegal optical disc. However, a method of directly recording the output signal of the comparator 365 without using the PLL circuit 366 and the flip-flop 367 is also conceivable. In this case, the information of the jitter does not disappear. However, when the reproduction signal is not synchronized, the noise jitter included in the reproduction of the signal is also recorded as it is, so that the SN of the reproduction signal of the optical disk generated by duplication decreases, and errors frequently occur during information reproduction. Become. Further, where the jitter is included in advance, such as in the region B, the jitter is further deteriorated, and an error is particularly likely to occur.

According to the above configuration, by recording the copy guard information by locally modulating the clock phase, the copy guard information can be recorded without affecting the normal reproduction of the optical disk. And
At the time of illegal duplication, the information can be lost. As a result, an optical disk that is difficult to illegally duplicate can be realized, and the copy guard information can be easily obtained by detecting the amplitude of the phase error signal of the PLL. An identifiable optical disk device can be realized.

In the third embodiment, the phase modulation is applied to the clock signal when the copy guard information is recorded. As a result, the jitter as shown in the lower part of FIG. If pits including the pits can be formed, the spirit of the present invention is lost even if the rising and falling edges of the bit stream of the recording information are directly shifted by, for example, switching the amount of delay when creating the optical disc. I can't.

The phase error to be actually added is desirably an amount that does not increase the error of the reproduced signal and that can provide a sufficient detection sensitivity. It is considered that about 1/8 to 1/4 of one clock cycle is appropriate as an amount satisfying these two conditions. In the third embodiment, the function of the comparator 331 is not specified, but it is required from the purpose of the present invention not to follow the level fluctuation of the reproduced signal due to the local phase fluctuation. That is, for example, in the case of the enlargement shift b and the reduction shift c as shown in the lower part of FIG. 25, the center position of the reproduced signal instantaneously moves up and down. When the comparator 331 is of an automatic tracking type, if this variation is tracked, the jitter of the binary signal PSG is reduced, and the discrimination sensitivity of the copy guard information is reduced. Therefore, it is better to set the tracking band of the comparator 331 to be equal to or lower than the tracking band of the PLL circuit 332.

Further, in the first to third embodiments, the target recording medium is a DVD-ROM or the like, but the present invention is not limited to such a type of recording medium, but may be a CD-ROM.
And DVD-RAM. If the position of a pit (recording mark) can be written by jitter modulation or radial modulation, it can be applied not only to the drilling method but also to other types of recording media employing a recording method such as phase transition or magnetization. Because you can.

The first embodiment is a copyright protection system using only jitter modulation, the second embodiment is a copyright protection system using only radial modulation, and the third embodiment is a copyright protection system using only radial modulation. Although the form was a copyright protection system using only phase modulation that is not limited to within the noise range, by mixing these modulations, it is possible to embed more sub-digital information with high recording density on the optical disk A copyright protection system with high security can also be provided.

[0117]

As is apparent from the above description, an optical disk on which main digital information and sub digital information are recorded, wherein the main digital information is formed at discrete reference positions on tracks of the optical disk. The sub-digital information is represented by whether or not the pit position is displaced by a very small amount with respect to the reference position.

As a result, the sub-digital information is embedded in the main digital information in a manner that is difficult to read. When the optical disk is copied only based on the presence or absence of pits, the sub-digital information is not copied. It is possible to distinguish whether the optical disk is an optical disk or a copied optical disk, and it is possible to prevent copyright infringement due to illegally copying a digital work on the optical disk as it is.

Here, the minute amount may be within a range of variation in pits observed at the time of reproduction of an optical disk on which only main digital information not including sub-digital information is recorded. This makes it extremely difficult for a normal reproducing apparatus to detect the sub-digital information buried in the jitter or the radial error, thereby preventing an illegal act of dubbing the main digital information including the sub-digital information.

Further, the sub-digital information has an edge which determines the length of the pit in the track direction, which is fixed to the edge position of the pit when recording only the main digital information without including the sub-digital information. The pits are recorded by phase modulation formed at either a position where the phase is advanced or delayed by a small amount, and the minute amount is a pit observed during reproduction of the optical disk on which only the main digital information not including the sub digital information is recorded. Or the sub-digital information is formed at one of a position where the pit is displaced inward and outward by a certain small amount in the radial direction from the center of the track in the radial direction. The small amount of light is recorded by the radial modulation, and only the main digital information without the sub digital information is recorded. It may be within the range of the radial error of pits observed during disk playback.

Thus, in the case of jitter modulation, when manufacturing such an optical disc, it is necessary to delay the channel signal corresponding to the pit train by a certain delay time.
Since the sub-digital information may be embedded while N / OFF, the phase modulation circuit for that purpose is simplified. Similarly, in the case of the radial modulation, the sub-digital information may be embedded while turning the recording head to be slightly deflected in the radial direction on / off.

In a certain area where the sub-digital information is recorded, the total number of pit edges recorded at the position where the phase is advanced and the number of edges of the pit recorded at the position where the phase is delayed. The total number of pits recorded at the position displaced toward the inner periphery and the position recorded at the position displaced toward the outer periphery are assumed to be substantially equal to each other, or in a certain area where the sub-digital information is recorded. The total number of pits may be substantially equal.

As a result, in the case of the jitter modulation, the amount of the leading component and the amount of the lag component included in the channel signal phase-modulated for recording the sub-digital information become substantially equal.
At the time of reproduction, it is possible to stably extract a channel bit clock synchronized with a channel signal, and the detection sensitivity of the phase modulation component is improved. Similarly, in the case of the radial modulation, the amount of the inner-side displacement and the amount of the outer-side displacement are substantially equal, so that the push-up signal is stably detected, the tracking servo is applied without having an offset, and the radial modulation component is detected with high sensitivity. Can be detected.

In the certain area, modulation for advancing the phase and modulation for delaying the phase are performed with equal probability for each unit code of the main digital information, or in the certain area, the main digital information is For each unit code, the modulation to be displaced inward and the modulation to be displaced outward may be performed with equal probability. As a result, at the time of reproduction, in the case of the jitter modulation, the edge of the phase-modulated channel signal and the edge of the phase-modulated channel signal are detected in a short repetition cycle, so that a more stable channel bit clock is obtained. The sub-digital information is extracted and restored with high accuracy. Similarly, in the case of the radial modulation, the channel signal displaced inward and the channel signal displaced outward are detected in a short repetition cycle, so that the push-up signal is detected more stably and the tracking servo is performed. This is reliably performed without any offset, and the sub-digital information is restored with high accuracy.

An optical disk recording apparatus according to the present invention is an apparatus for recording sub-digital information superimposed on main digital information on an optical disk, wherein pits are formed at discrete reference positions on tracks of the optical disk. Main digital information recording means for recording the main digital information, and sub-digital information recording means for recording the sub-digital information by displacing the position of the pit by a very small amount with respect to the reference position, The sub-digital information recording means further includes a random number generation unit that generates a random number sequence, and a logic conversion unit that performs a logical conversion on the random number sequence generated from the random number generation unit based on the sub-digital information, The modulator may generate the PE modulation signal based on the random number sequence logically converted by the logical converter.

As a result, in the case of the jitter modulation, the edge position of the pit is subjected to the jitter modulation based on the random number sequence, so that it becomes difficult to decode the sub digital information buried in the jitter. Similarly, in the case of the radial modulation, the pit recording position in the radial direction is subjected to the radial modulation based on a random number sequence, so that it becomes difficult to decode the sub-digital information buried in noise.

Here, the sub-digital information recording means further has a sub-digital information recording section for keeping the sub-digital information secret, and the logical conversion section is a sub-digital information recording section for holding the sub-digital information. The calculation of the exclusive OR of each bit value forming the digital information and the random number sequence of a fixed length generated by the random number generation unit may be repeated for all the bits of the sub digital information. As a result, instead of embedding one random number sequence as it is, a plurality of random number sequences obtained by taking an exclusive OR with secret information are embedded, so that it becomes more difficult to decode the sub-digital information.

An optical disk reproducing apparatus according to the present invention is an optical disk reproducing apparatus in which main digital information and sub digital information are recorded, wherein pits formed at discrete reference positions on tracks of the optical disk are recorded. Main digital information reproducing means for reproducing main digital information by detecting; a clock extracting means for extracting a channel bit clock synchronized with the reference position from a channel signal corresponding to the detected pit row; And a sub-digital information extracting means for extracting sub-digital information based on a phase difference with the channel bit clock, or a reproducing apparatus for an optical disc on which main digital information and sub-digital information are recorded, Detecting pits formed at discrete reference positions on tracks of the optical disk. Main digital information reproducing means for reproducing main digital information, a radial error detecting means for detecting a radial displacement from the track center with respect to the detected pit position, and a sub-digital based on the detected displacement. A sub-digital information extracting means for extracting information may be provided.

Here, the optical disk reproducing device further performs the reproducing operation of the main digital information when the sub-digital information generating section determines that the magnitude of the integrated value is not larger than the threshold value. A reproduction restriction means for restricting the reproduction may be provided. Further, the sub-digital information generation unit may be configured to determine whether the integrated value of the integration unit has a first correlation greater than a predetermined positive threshold value or to determine whether the integration value is a predetermined negative threshold value. It is determined whether there is a smaller second correlation or no correlation that is neither of them. If there is a correlation, the result is output as sub-digital information, The playback device further includes secret information storage means for storing secret information, and verification means for comparing the secret information stored in the secret information storage means with the sub digital information generated by the sub digital information generation unit, The reproduction restricting means may restrict the reproduction operation of the main digital information even when it is determined in the comparison by the verification means that they do not match, in addition to the above case.

As a result, an optical disc reproducing apparatus having a copyright protection function capable of reading the sub-digital information embedded by the above-mentioned jitter modulation and radial modulation is realized. Further, in the optical disc according to the present invention, in the above optical disc, the main digital information is:
An information pit sequence formed in synchronization with a predetermined reference clock, and the sub-digital information is copy guard information represented by a pit sequence formed by locally adding a phase error to the reference clock. There may be.

As a result, the reference clock at the time of recording is phase-modulated in accordance with the copy guard information, and the data string is recorded with the phase-modulated clock, thereby making duplication difficult. By detecting the value as a value, copy guard information can be detected, and an illegal copy can be easily identified with a simple circuit configuration.

As described above, by the jitter modulation and the radial modulation according to the present invention, illegal acts such as dubbing of the optical disk storing the digital work are prevented, and sound distribution of the digital work is ensured. Its practical value is extremely high.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical disk recording device according to a first embodiment of the present invention.

FIG. 2 is a timing chart of main signals in the same device.

FIG. 3 is a block diagram showing a detailed configuration of a formatter of the device.

FIG. 4 is a diagram showing a correspondence relationship between a secret key, a pseudo-random number sequence, and recorded data.

FIG. 5 is a circuit diagram showing a detailed configuration of a pseudo random number generator of the same device.

FIG. 6 is a block diagram showing a detailed configuration of a phase modulator of the device.

FIG. 7 is an external view showing a surface of a DVD on which pits are formed by the device.

FIG. 8 is a graph showing a frequency distribution of jitter with respect to pits formed by the apparatus.

FIG. 9 is a block diagram illustrating a configuration of an optical disc reproducing device according to the first embodiment of the present invention.

FIG. 10 is a block diagram showing a detailed configuration of a clock extractor of the device.

FIG. 11 is a circuit diagram showing a detailed configuration of a phase error signal separator in the clock extractor.

12 is a timing chart of each signal for explaining the operation of the phase error signal separator shown in FIG.

FIG. 13 is a block diagram showing a detailed configuration of a reproduction signal processing circuit of the device.

FIG. 14 is a circuit diagram showing a detailed configuration of a synchronous detector of the device.

FIG. 15 is a diagram showing an example of an analog signal waveform output from an integrator of the same device.

FIG. 16 is a block diagram illustrating a detailed configuration of a verification unit of the apparatus.

FIG. 17 is a block diagram illustrating a configuration of an optical disc recording device according to a second embodiment of the present invention.

FIG. 18 is a timing chart of main signals in the device.

FIG. 19 is an external view showing the surface of a DVD on which pits have been formed by the device.

FIG. 20 is a graph showing a radial error frequency distribution of pits formed by the apparatus.

FIG. 21 is a block diagram illustrating a configuration of an optical disc reproducing device according to a second embodiment of the present invention.

FIG. 22 is a block diagram showing a detailed configuration of a portion related to generation of a radial error signal in a reproducing head of the same device.

FIG. 23 is a block diagram showing a detailed configuration of a radial error detector of the same device.

FIG. 24 is a configuration diagram of an optical disc according to a third embodiment of the present invention.

FIG. 25 is a partial view of the optical disc shown in FIG. 24.

FIG. 26 is a block diagram of an optical disc device according to a third embodiment of the present invention.

FIG. 27 is a timing chart for explaining the operation of the optical disk device shown in FIG. 26;

FIG. 28 is a timing chart for explaining the operation of the optical disc device shown in FIG. 26;

FIG. 29 is a block diagram of a typical optical disk duplication device for explaining the effects of the present invention.

FIG. 30 is a diagram illustrating a recording area of a DVD according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Formatter 2 Pseudo random number generator 3 Timing generator 4 Exclusive OR gate 5 PE modulator 6 Phase modulator 7 Recording channel 8 Recording head 9 DVD 11 Reproduction head 12 Reproduction channel 13 Reproduction signal processing circuit 14 Clock extractor 15 Synchronization Detector 16 Verifier 17 Pseudorandom number generator 18 Radial modulator 19 Tracking actuator 20 Radial error detector 100, 200 Optical disk recording device 110, 210 Optical disk reproducing device 311 Optical disk 312 Copy guard information 321 Pits 331 Comparator 332 PLL circuit 332a Phase comparison 332b LPF 332c VCO 333 Amplitude detector 334 Flip-flop 361 Optical disk 362 Optical disk 363 Reproduction head 364 Reproduction amplifier 365 Comparator Capacitor 366 PLL circuit 367 flip 368 optical modulator 369 recording head

Continuing from the front page (72) Inventor Shinichi Tanaka 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 5D029 WA18 WA20 5D044 AB05 AB07 BC03 CC06 DE02 DE27 DE50 GK12 GK17 5D066 DA03 DA16 5D090 AA01 BB02 CC04 DD01 EE13 FF02 FF14 FF36 GG09 GG33

Claims (43)

[Claims] 1. An optical disc on which main digital information and sub digital information are recorded, wherein the main digital information is represented by the presence or absence of pits formed at discrete reference positions on tracks of the optical disc, An optical disc, wherein the sub-digital information is expressed by whether or not the position of the pit is displaced by a very small amount with respect to the reference position. 2. The method according to claim 1, wherein the minute amount is within a range of variation of the pit observed at the time of reproduction of the optical disk on which only the main digital information including no sub digital information is recorded. Item 7. The optical disc according to Item 1. 3. The sub-digital information has an edge which determines the length of a pit in the track direction, and the edge which determines a length of the pit in a case where only main digital information is recorded without including the sub-digital information. Recorded by phase modulation formed at one of a position advanced or delayed by a small amount, and the minute amount is a pit observed during reproduction of an optical disc on which only main digital information not including sub-digital information is recorded. 3. The jitter of claim 2, wherein
An optical disc as described. 4. In a certain area where the sub-digital information is recorded, the total number of pit edges recorded at the position advanced in phase and the number of edges of pits recorded in the position delayed in phase are determined. 4. The optical disc according to claim 3, wherein the total number is substantially equal. 5. The modulation according to claim 4, wherein, in the certain area, modulation for advancing the phase and modulation for delaying the phase are performed with equal probability for each unit code of the main digital information. optical disk. 6. The radial modulation, wherein the sub-digital information is formed at a position where a pit is displaced inward and outward by a certain small amount in the radial direction from a track center in a radial direction. The optical disk according to claim 2, wherein the minute amount is within a range of a pit radial error observed during reproduction of an optical disk on which only main digital information not including sub-digital information is recorded. . 7. In a certain area where the sub-digital information is recorded, a total number of pits recorded at the position displaced inward and a total number of pits recorded at the position displaced outward. 7. The optical disk according to claim 6, wherein 8. The method according to claim 8, wherein in the certain area, the modulation to be displaced inwardly and the modulation to be displaced outwardly are performed with equal probability for each unit code of the main digital information. The optical disc according to claim 7. 9. The main digital information is an information pit string formed in synchronization with a predetermined reference clock, and the sub digital information is formed by locally adding a phase error to the reference clock. 2. Copy guard information represented by a set of pit strings.
An optical disc as described. 10. The optical disk according to claim 9, wherein the sub-digital information is subjected to phase modulation so that the sub-digital information is detected as jitter when reproducing a pit string. 11. The optical disk according to claim 9, wherein the phase error fluctuation band is sufficiently higher than a PLL follow-up band at the time of reproducing information. 12. The optical disk according to claim 9, wherein an average of a phase change in the phase error is zero. 13. The phase error is successively shifted by the same amount at the beginning and end of a recording pit and in the same direction, and by the shift in the same amount at the beginning and end of the recording pit and in the opposite direction. 10. The optical disk according to claim 9, wherein: 14. The optical disk according to claim 9, wherein key information correlated with copy guard information is further formed on the optical disk. 15. An apparatus for recording on an optical disk by superimposing sub-digital information on main digital information, wherein the main digital information is recorded by forming pits at discrete reference positions on tracks of the optical disk. An optical disc recording apparatus comprising: main digital information recording means; and sub-digital information recording means for recording the sub-digital information by displacing a pit position by a very small amount with respect to the reference position. 16. The method according to claim 16, wherein the minute amount is within a range of variation of the pit observed at the time of reproducing the optical disk on which only the main digital information including no sub digital information is recorded. Item 16. An optical disk recording device according to item 15. 17. The sub-digital information recording means sets an edge that determines the length of a pit in the track direction,
In the case where only the main digital information is recorded without including the sub-digital information, the sub-digital is formed by a phase modulation formed at one of a position where the phase is advanced or delayed by a certain small amount with respect to the edge position of the pit. The information is recorded, and the minute amount is within a range of a pit jitter observed at the time of reproduction of an optical disc on which only main digital information without sub-digital information is recorded.
7. The optical disk recording device according to item 6. 18. The sub-digital information recording means, in a predetermined area where sub-digital information is recorded, the total number of pit edges recorded at the position advanced in phase and the pit edge recorded in the position delayed in phase. 18. The optical disk recording apparatus according to claim 17, wherein the phase modulation is performed so that the total number of edges of the pits becomes substantially equal. 19. The method according to claim 19, wherein the sub-digital information recording means performs, for each unit code of the main digital information, a modulation for advancing a phase and a modulation for delaying a phase with equal probability in the predetermined area. Item 19. The optical disk recording device according to Item 18. 20. The sub-digital information recording means, based on the sub-digital information, performs P-inversion at the center of each channel code of main digital information to be recorded.
A PE modulator for generating an E-modulated signal; and, during the time when the PE-modulated signal indicates the first state, advance the phase of the edge of the channel signal indicating the pit position of the main digital information by the minute amount, A phase modulator for delaying the phase of the edge by the minute amount during a time when the signal indicates the second state; and a writer for forming pits on the optical disk based on the modulated channel signal generated by the phase modulator. 20. The optical disk recording device according to claim 19, comprising: 21. The sub-digital information recording means forms a pit at one of a position displaced radially inward and outward from the center of the track by a constant small amount toward the inner periphery and a position displaced toward the outer periphery. The sub-digital information is recorded by radial modulation, and the minute amount is within a range of a pit radial error observed during reproduction of an optical disk on which only main digital information not including sub-digital information is recorded. 17. The optical disk recording device according to claim 16, wherein: 22. The sub-digital information recording means, in a fixed area where sub-digital information is recorded, a total number of pits recorded at the position displaced inward and a position recorded at the position displaced outward. 22. The optical disk recording apparatus according to claim 21, wherein the radial modulation is performed so that the total number of pits is substantially equal. 23. The sub-digital information recording means performs, with equal probability, modulation for displacing inward and outward for each unit code of the main digital information in the predetermined area. The optical disk recording device according to claim 22, characterized in that: 24. The sub-digital information recording means, based on the sub-digital information, performs P-inversion at the center of each channel code of main digital information to be recorded.
A PE modulation unit that generates an E modulation signal; and a time when the PE modulation signal indicates the first state.
A signal for displacing the position of the beam spot for forming a pit in the radial direction from the center of the track by a constant small amount to the inner peripheral side is generated, and at a time when the PE modulation signal indicates the second state. A radial modulation unit that generates a signal for displacing the position of the beam spot for forming a pit in the radial direction from the track center in the radial direction by a constant small amount, and a signal generated by the radial modulation unit. 24. The optical disk recording apparatus according to claim 23, further comprising: a beam deflecting unit that displaces a position of a beam spot based on the detected value. 25. The sub-digital information recording means, further comprising: a random number generation unit for generating a random number sequence; and a logic conversion unit for performing a logical conversion on the random number sequence generated from the random number generation unit based on the sub-digital information. 25. The optical disc recording apparatus according to claim 21, wherein the PE modulation unit generates the PE modulation signal based on a random number sequence logically converted by the logical conversion unit. 26. The sub-digital information recording means further includes a sub-digital information recording unit for keeping the sub-digital information secret, and the logical conversion unit comprises a sub-digital information held in the sub-digital information recording unit. Calculating an exclusive OR of each bit value constituting the information and a random number sequence of a fixed length generated by the random number generator, for all bits of the sub-digital information; 26. The optical disk recording device according to item 25. 27. A method for recording on an optical disc by superimposing sub-digital information on main digital information, wherein the main digital information is recorded by forming pits at discrete reference positions on tracks of the optical disc. An optical disc recording method, comprising: a main digital information recording step; and a sub-digital information recording step of recording the sub-digital information by displacing a pit position by a very small amount with respect to the reference position. 28. The method according to claim 28, wherein the minute amount is within a range of variation of the pits observed at the time of reproducing an optical disk on which only main digital information including no sub digital information is recorded. Item 28. The optical disk recording method according to Item 27. 29. In the sub-digital information recording step, an edge which determines the length of the pit in the track direction is fixed with respect to the edge position of the pit when only the main digital information is recorded without including the sub-digital information. The sub-digital information is recorded by phase modulation formed at one of a position where the phase is advanced or delayed by the minute amount, and the optical disk on which only the main digital information is recorded without the minute amount. 3. The method according to claim 2, wherein the jitter is within a range of pit jitter observed during reproduction of the pit.
9. The optical disk recording method according to item 8. 30. In the sub-digital information recording step, a pit is formed at one of a position displaced inward and outward by a certain small amount in the radial direction from a track center in the radial direction. The sub-digital information is recorded by radial modulation, and the minute amount is within a range of a pit radial error observed during reproduction of an optical disk on which only main digital information not including sub-digital information is recorded. 29. The optical disk recording method according to claim 28, wherein: 31. A reproducing apparatus for an optical disc on which main digital information and sub digital information are recorded, wherein the main digital information is reproduced by detecting pits formed at discrete reference positions on tracks of the optical disc. Main digital information reproducing means, a clock extracting means for extracting a channel bit clock synchronized with the reference position from a channel signal corresponding to the detected pit row, and a phase difference between the channel signal and the channel bit clock. An optical disc reproducing apparatus, comprising: sub-digital information extracting means for extracting sub-digital information based on the sub-digital information. 32. The sub-digital information extracting means, comprising: a data sequence storage unit for storing a data sequence in advance; and detecting a correlation between the data sequence stored in the data sequence storage unit and the phase difference; 32. The optical disc reproducing apparatus according to claim 31, further comprising: a correlation detecting unit that extracts the sub-digital information based on the result. 33. The sub-digital information extracting means further includes, based on the phase difference, a leading error signal indicating only an advance of the phase of the channel signal with respect to the channel bit clock and a delay of the phase of the channel signal. And a phase separation unit that generates a lag error signal indicating only the phase error signal. The correlation detection unit, based on the data sequence, synchronously detects the advance error signal and the lag error signal to perform the correlation. 33. The method according to claim 32, wherein the property is detected.
An optical disk reproducing apparatus according to claim 1. 34. The correlation detecting section, based on the data sequence, generates a PE modulation signal that is logically inverted at the center of each channel code of the read main digital information.
An E-modulation unit, for the time when the PE-modulated signal indicates the first state, adds the leading amount of the phase indicated by the leading error signal and integrates while subtracting the delayed amount of the phase indicated by the lagging error signal And an accumulator for subtracting a leading amount of the phase indicated by the leading error signal and adding a delay of the phase indicated by the lagging error signal during a time when the PE modulation signal indicates the second state. 34. The optical disc reproducing apparatus according to claim 33, further comprising: a sub-digital information generating unit that generates the sub-digital information based on an integrated value by the integrating unit. 35. The data sequence is a random number sequence, wherein the integrating unit integrates the advance and the delay with respect to the constant length random number sequence; It is determined whether or not the magnitude of the integrated value of the series by the integrating unit is larger than a predetermined threshold value, and if so, the sub-digital information is output based on the result. 35. The optical disc playback device according to claim 34. 36. A reproducing apparatus for an optical disc on which main digital information and sub digital information are recorded, wherein the main digital information is reproduced by detecting pits formed at discrete reference positions on tracks of the optical disc. Main digital information reproducing means, radial error detecting means for detecting a radial displacement from the track center with respect to the detected pit position, and sub-digital information for extracting sub-digital information based on the detected displacement. An optical disc reproducing apparatus comprising: an extracting unit. 37. The sub-digital information extracting means, comprising: a data sequence storage unit for storing a data sequence in advance; and detecting a correlation between the data sequence stored in the data sequence storage unit and the direction of the displacement. 37. The optical disc reproducing apparatus according to claim 36, further comprising: a correlation detecting unit that extracts the sub-digital information based on the result. 38. The sub-digital information extracting means further includes, based on the detected displacement, an inner-peripheral-side displacement signal indicating that the pit is formed radially inward from the track center. A radial error separating unit that generates an outer peripheral displacement signal indicating that the inner peripheral displacement signal is formed on the outer peripheral side, the correlation detector detects the inner peripheral displacement signal and the outer peripheral displacement based on the data sequence. The optical disc reproducing apparatus according to claim 37, wherein the correlation is detected by synchronously detecting a signal. 39. The PE modulation section, which generates a PE modulation signal that is logically inverted at the center of each channel code of the read main digital information based on the data sequence, In the time when the signal indicates the first state, the displacement to the inner periphery indicated by the inner displacement signal is added and the displacement to the outer periphery indicated by the outer displacement signal is integrated while subtracting the displacement to the outer periphery, During the time when the PE modulation signal indicates the second state, the displacement toward the inner periphery indicated by the inner displacement signal is subtracted and the displacement toward the outer periphery indicated by the outer displacement signal is added. 39. The optical disc reproducing apparatus according to claim 38, further comprising: an accumulating unit for accumulating; and a sub-digital information generating unit for generating the sub-digital information based on an integrated value of the accumulating unit. 40. The data sequence is a random number sequence, wherein the integrating unit integrates the displacement toward the inner periphery and the displacement toward the outer periphery with respect to the random number sequence having a fixed length, The information generation unit determines whether or not the magnitude of the integrated value of the constant-length random number sequence by the integrating unit is greater than a predetermined threshold value. 40. The optical disk reproducing device according to claim 39, wherein the optical disk reproducing device outputs 41. The optical disk reproducing device further restricts the reproducing operation of the main digital information when the sub-digital information generating section determines that the magnitude of the integrated value is not larger than the threshold value. 41. The optical disk reproducing apparatus according to claim 35, further comprising a reproduction restricting means for performing the operation. 42. The sub-digital information generating section is configured to determine whether the integrated value obtained by the integrating section has a first correlation greater than a predetermined positive threshold value, or whether the integrated value has a predetermined negative value. It is determined whether there is a second correlation smaller than the threshold or no correlation that is neither of them. If there is a correlation, the result is output as sub-digital information. The optical disc reproducing apparatus further includes: secret information storage means for storing secret information; and verification means for comparing the secret information stored in the secret information storage means with the sub-digital information generated by the sub-digital information generation unit. Wherein the reproduction restricting means restricts the reproducing operation of the main digital information even when it is determined in the comparison by the verification means that they do not match, in addition to the above case. The optical disk reproducing apparatus according to claim 41, wherein that. 43. An apparatus for reproducing an optical disk, comprising:
In the optical disc, an information pit row is formed by a predetermined reference clock, and copy guard information is formed by forming a pit row to which a phase error is locally added. An optical disk reproducing apparatus comprising: means for identifying copy guard information based on a variation in error amplitude.