JP4051515B2 - Disc recording apparatus, disc recording method, optical disc reproducing device, optical disc reproducing method, optical disc, and signal processing circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention, DeDisk recording device, DeDisc recording method, optical disc playback apparatus, and optical disc playback method,lightdiskAnd signal processing circuitThe present invention can be applied to, for example, an optical disc for recording audio data, and the recording apparatus and reproducing apparatus. The present invention provides an optical discInner circumferential direction orPits etc. in the outer circumferential directionPredetermined amountBy recording the sub-data by displacing it, it can be reproduced by an optical pickup that reproduces this data string, and can be copied by illegal copying without affecting the reproduction of the data string by a pit string or the like. It is difficult to record various data.
[0002]
[Prior art]
Conventionally, compact discs perform data processing on a data string to be recorded and then perform EFM modulation (Eight to Fourteen Modulation) to form a pit string having a period of 3T to 11T with respect to a predetermined basic period T. Audio data and the like are recorded.
[0003]
In contrast, a management data recording area is formed in the inner lead-in area, and a desired performance or the like can be selectively reproduced by a TOC (Table Of Contents) recorded in the recording area. Has been made.
[0004]
The compact disc on which various data is recorded in this way has an IFPI (International Federation of the Phonographic Industry) code recording area for the purpose of preventing piracy on the inner periphery of the lead-in area. The recording area is marked with a code indicating the manufacturer, manufacturing location, disk number, etc., so that the history of the compact disk can be visually confirmed.
[0005]
[Problems to be solved by the invention]
By the way, in such an inscription, it is considered that the illegal copy can be identified by the presence or absence of this inscription by checking the history of the compact disc. However, this stamp has a drawback that it is difficult to reproduce by an optical pickup of a compact disc player because it is for visual confirmation. Thus, in order to identify the illegal copy by the stamp and reflect the presence or absence of the stamp in the reproduction process, a dedicated reproduction mechanism is eventually required to reproduce the stamp.
[0006]
In addition, the codes recorded by these methods are recorded by the same method as normal pits and confirmed by visual observation, by removing the protective film and the aluminum reflective film of the compact disc and creating a stamper, etc. There was a problem that duplication was possible and this caused illegal copying.
[0007]
As a result, it is possible to record various data that can be reproduced by an optical pickup that reproduces audio data and difficult to copy by illegal copying without affecting the reproduction of audio data by a pit row. If possible, this data can be used to eliminate illegal copying.
[0008]
  The present invention has been made in consideration of the above points, and has no effect on the reproduction of data by a pit row or the like, can be reproduced by an optical pickup for reproducing the data by the pit row or the like, and illegally copied. Depending on the type of data, it may be difficult to copy, and data that prohibits illegal copying can be recorded.DeDisk recording device, DeDisc recording method, optical disc using the same, optical disc playback apparatus applied to the optical disc, and optical disc playback methodThese signal processing circuitsIs to try to propose.
[0009]
[Means for Solving the Problems]
  In order to solve such a problem, the invention according to claim 1 or claim 8 is applied to an optical disc recording apparatus or an optical disc recording method to generate a main modulation signal in accordance with main data, and this main modulation Sub-data used to protect the copyright of the main data by forming a pit row or mark row on the optical disc by irradiating a laser beam according to the signalAllocate multiple bits of binary numbers that are pseudo-random numbers to 1 bit ofA secondary modulation signal is generated, and the irradiation position of the recording beam is set in the inner circumferential direction or the outer circumferential direction of the disc based on the track center of the track by the pit row or the track mark row according to the secondary modulation signal. Displace a predetermined amount toThe push-pull signal obtained at the time of reproduction has a predetermined amount that is a minute amount such that the signal level due to the displacement is not more than a noise level, and the signal of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub data is assigned The level is integrated so that the 1 bit is a reproducible displacement amount.
[0010]
  In the invention according to claim 15, when applied to an optical disc, main data is recorded by the length of pits or marks in the direction along the track and the interval between pits or the interval between marks,The sub-data generated by allocating a plurality of bits of a binary number sequence that is a pseudo-random number to one bit of the sub-data used for copyright protection of the main data and processing the sub-data with the binary number sequence. In accordance with a secondary modulation signal corresponding to a plurality of bits per 1 bit, 1 bit of the sub data is assigned to a plurality of pits or marks,The pits or marks in the inner or outer circumferential direction with reference to the track center of the trackAccording to the sub data and the binary sequencePredetermined amount of displacementDeputyEnsure that data is recorded.The predetermined amount is a minute amount in which the signal level due to the displacement is equal to or less than the noise level in the push-pull signal obtained at the time of reproduction, and the push-pull signal in the plurality of pits or marks to which one bit of the sub data is assigned. The signal level is integrated so that the 1 bit is a reproducible displacement amount.
[0011]
  Claim 21In the invention according to the present invention, the signal level changes according to the displacement of the pits or marks in the inner and outer circumferential directions with reference to the track center when applied to the optical disk reproducing apparatus.Push-pullSignal is output and the playback signal is used as a reference.Push-pullBy performing signal processing on the signal, sub-data used for copyright protection of the main data recorded by a predetermined amount of displacement of the pits or marks in the inner circumferential direction or the outer circumferential direction with respect to the track center is reproduced. InAn integration unit that integrates the signal level of the push-pull signal on the basis of a logical level of a binary number sequence that is a pseudo-random number; and an integration result processing unit that processes an integration result to detect the sub data, The push-pull signal obtained at the time of reproduction has a predetermined amount that is a minute amount such that the signal level due to the displacement is not more than a noise level, and the signal of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub data is assigned The level is integrated so that the 1 bit is a reproducible displacement amount.
[0012]
  Further, in the invention according to claim 24, the main data recorded by the pit row or the mark row is reproduced from the return light obtained by irradiating the optical disc with the laser beam as applied to the reproducing method of the optical disc,A push-pull signal whose signal level changes according to the displacement of the pit or mark in the inner and outer circumferential directions with respect to the track center is generated, and the inner circumference with respect to the track center is generated by signal processing of the push-pull signal. The sub data used for protecting the copyright of the main data recorded by a predetermined amount of displacement of the pit or mark in the direction or the outer peripheral direction is reproduced. In more detail, the signal level of the push-pull signal is integrated on the basis of the logic level of a binary sequence that is a pseudo-random number, the integration result is processed to detect the sub data, and the predetermined amount is Integrate the signal level of the push-pull signal in a plurality of pits or marks to which one bit of the sub-data is assigned, and the signal level due to the displacement is a minute amount or less in the push-pull signal obtained at the time of reproduction Then, the 1 bit is set to a reproducible displacement amount.
[0013]
  Claim 1 or Claim8According to the configurationTheRecorded by a mark or markMainDo not impair playback of the dataDeputyData can be recorded. AlsoDeputyIt is difficult to copy data by illegal copying by assigning various data such as prohibiting illegal copying.MainThe data can be recorded in a reproducible manner by an optical pickup that reproduces the data.
[0014]
  And claims15According to the configuration, StrangeBy selecting the unit quantityMainData reproduction is not impaired. AlsoDeputyIt is difficult to copy data by illegal copying by assigning various data such as prohibiting illegal copying.MainThe data can be recorded in a reproducible manner by an optical pickup that reproduces the data.
[0015]
  And claims21According to the configuration, the main data recorded by the pit row or mark row is reproduced from the optical disc having the above-described configuration, and the sub data recorded by a predetermined amount of displacement in the inner circumferential direction or outer circumferential direction of the pit or mark is recorded. Data can be played back.
[0016]
  Claim 24According to the configuration according to the present invention, the data reproduction by the pit row or the like is not affected at all, the data can be reproduced by the optical pickup for reproducing the data by the pit row or the like, and it is difficult to copy by illegal copying. The main and sub data can be reproduced from the optical disk on which various data prohibiting illegal copying are recorded.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
[0018]
(1) Configuration of the embodiment
FIG. 1 is a block diagram showing an optical disc apparatus according to an embodiment of the present invention. The optical disk apparatus 1 records the audio data D1 output from the digital audio tape recorder 3 by exposing the disk master 2.
[0019]
That is, in this optical disc apparatus 1, the spindle motor 4 drives the disc master 2 to rotate, and outputs an FG signal FG whose signal level rises every time it rotates by a predetermined angle from the FG signal generation circuit held at the bottom. The spindle servo circuit 5 controls the rotational speed of the spindle motor 4 in accordance with the exposure position of the disk master 2 with reference to the FG signal FG, thereby rotating the disk master 2 at a predetermined rotational speed.
[0020]
The recording laser 7 is constituted by a gas laser or the like, and emits a laser beam L1 for exposure of the disc master 2. The optical modulator 8A is composed of, for example, an electroacoustic optical element, and emits the laser beam L1 by performing on-off modulation in accordance with an EFM (Eight to Fourteen Modulation) signal S2 output from the modulation circuit 9.
[0021]
The optical deflector 8B is composed of, for example, an electroacoustic optical element, and diffracts and emits the laser beam L2 output from the optical modulator 8A in accordance with the key modulation signal KS output from the key modulation circuit 10. The laser beam L2 is emitted while changing the emission direction to a direction corresponding to the inner and outer circumferential directions of the disc master 2.
[0022]
The mirror 12 bends the optical path of the laser beam L3 output from the optical deflector 10 and emits it toward the disc master 2. The objective lens 13 condenses the light emitted from the mirror 12 on the recording surface of the master disc 2. The mirror 12 and the objective lens 13 are sequentially moved from the inner peripheral side to the outer peripheral side of the disc master 2 in synchronization with the rotation of the disc master 2 by a thread mechanism (not shown).
[0023]
As a result, the optical disc apparatus 1 sequentially displaces the condensing position of the laser beam L3 from the inner peripheral side to the outer peripheral side of the disc master 2, and forms a spiral track on the disc master 2. Further, in this track formation process, the optical disk apparatus 1 sequentially turns on and off the laser beam L1 by the optical modulator 8A according to the EFM signal S2, thereby sequentially forming pit rows along the track according to the EFM signal S2. Further, the emission direction of the laser beam L2 is displaced by the optical deflector 8B, and the pits are displaced in the inner and outer circumferential directions of the disc master 2 in accordance with the key modulation signal KS.
[0024]
Thus, in this optical disc apparatus 1, the optical disc produced from this master disc 2 is reproduced under the tracking control with the same characteristics as the conventional compact disc player, and the pit train is generated with the same phase margin as the conventional one. The pits in the inner and outer peripheral directions of the disc master 2 are set to a small value so that the data according to the above can be reproduced, that is, the reproduction of the data recorded by the pit train is not impaired. Specifically, in this embodiment, this displacement is at most 1/50 or less of the track pitch.
[0025]
The digital audio tape recorder 3 outputs the audio data D1 to the encryption circuit 15. The encryption circuit 15 encrypts the audio data with a DES (Data Encryption Standard) code based on the key data KY, and outputs the encrypted data.
[0026]
The subcode generator 16 sequentially generates and outputs subcode data SC according to a format defined for the compact disc. The modulation circuit 9 generates an EFM signal S2 by processing the output data S1 and the subcode SC of the encryption circuit 15 in accordance with a format defined for the compact disc. That is, the modulation circuit 9 adds an error correction code to the output data S1 and the subcode data SC of the encryption circuit 15, performs interleaving processing, and further performs EFM modulation to generate an EFM signal S2.
[0027]
Thereby, in the optical disc apparatus 1, the audio data D1 is encrypted and recorded on the disc master 2 by a pit string.
[0028]
The key modulation circuit 10 generates and outputs a key modulation signal KS based on the key data KY, whereby the optical disk apparatus 1 records the key data KY by displacement in the inner and outer peripheral directions of the pits. In the optical disc apparatus 1, key data KY is generated by a read-only memory or the like.
[0029]
FIG. 2 is a block diagram showing the key modulation circuit 10 in detail. As shown in FIG. 3, the key modulation circuit 10 inputs the EFM signal S2 (FIG. 3 (A)) to the PLL circuit (Phase Locked Loop) 20, where the clock CK (FIG. 3 (B)) is received from the EFM signal S2. ).
[0030]
The synchronization detection circuit 21 sequentially latches the EFM signal S2 with reference to the clock CK, and detects the synchronization pattern from the EFM signal S2 by determining the continuous logic level. The synchronization detection circuit 21 outputs a frame clock FCK whose logic level rises at the cycle of this synchronization pattern. Thus, in the compact disc format, a synchronization pattern is arranged at the head of each frame, and each frame is composed of 588 channel clocks. Therefore, the synchronization detection circuit 21 is a frame whose logic level rises every 588 clock cycles. The clock FCK is output.
[0031]
The subcode detection circuit 22 monitors the EFM signal S2 with reference to the clock CK, and decodes the subcode from the EFM signal S2. Further, the subcode detection circuit 22 monitors time information in the decoded subcode, and outputs a 1-second detection pulse SECP in which the signal level rises every time this time information changes by 1 second. Thus, in the compact disk format, 98 frames are allocated per second, so that the subcode detection circuit 22 outputs a 1-second detection pulse SECP so that the signal level rises at the 98 pulse period of the frame clock (FCK). Will do.
[0032]
The counter 23 is a counter that increments the frame clock FCK, and resets the count value CT when the one-second detection pulse SECP rises. As a result, the counter 23 forms a ring counter in which the count value CT circulates in a cycle of 1 second, and the count value CT changes in synchronization with the frame clock FCK.
[0033]
The data selector 24 outputs data held with the count value CT of the counter 23 as an address. Here, the count value CT of the counter 23 is cyclically changed by the number of frames per second (98 frames) in synchronization with the synchronization pattern, so that the data selector 24 uses the count value CT as an address. Thus, 98 types of data are sequentially output in synchronization with the synchronization pattern. Further, in the count value CT of the counter 23, the count value circulates in a cycle of 1 second by the 1-second detection pulse SECP, so that the data selector 24 repeats these 98 types of data in a cycle of 1 second.
[0034]
In this embodiment, the data selector 24 is assigned 1-bit data as the 98 types of data, and repeats at a 1-second cycle to output the 98-bit data in synchronization with the synchronization pattern. ing. Further, each bit of the 54-bit key data KY is assigned to a predetermined bit of the 98-bit data, and each bit of data having no meaning is assigned to the remaining 44-bit bits. In this embodiment, fixed value data KZ is assigned as data having no meaning.
[0035]
The M-sequence generation circuit 25 includes a plurality of cascade-connected flip-flops and an exclusive OR circuit, and sets initial values in the plurality of flip-flops according to the frame clock FCK output from the synchronization detection circuit 21. Further, the M-sequence generation circuit 25 sequentially transfers the contents set in this manner in synchronization with the clock CK, and returns the feedback between predetermined stages, whereby an M-sequence random number in which logic 1 and logic 0 appear with equal probability. Data MS is generated. As a result, the M-sequence generation circuit 25 outputs random number data MS that is a binary sequence of pseudo-random numbers synchronized with the clock CK so that the same pattern is repeated in one frame cycle which is 588 clock cycles.
[0036]
The exclusive OR circuit (X) 27 receives the random number data MS and the output data KD of the data selector 24, and outputs an exclusive OR signal MS1 thereof (FIG. 3C). That is, the exclusive OR circuit 27 outputs the random number data MS as it is when the output data KD of the data selector 24 is logic 0, whereas the exclusive OR circuit 27 outputs the random number data MS when the output data KD of the data selector 24 is logic 1. Output with the logic level inverted. As a result, the exclusive OR circuit 27 modulates the key data KY constituting the output data KD with a random number and outputs it.
[0037]
The flip-flop 28 latches and outputs the output data MS1 of the exclusive OR circuit 27 with reference to the rising edge of the EFM signal S2 (FIG. 3 (D)). Here, in this embodiment, the scanning start end side edge of each pit corresponds to the rising edge of the EFM signal S2 in the optical disc created from the disc master 2 by the exposure of the disc master 2 by the EFM signal S2. It will be. As a result, the flip-flop 28 latches the output data MS1 assigned at the timing of starting each pit from the output data MS1 of the exclusive OR circuit 27 that is sequentially output in the clock cycle that is the reference cycle for pit formation. Until the formation of at least one pit is completed, the logic level of the latched output data MS1 is maintained.
[0038]
The amplifier circuit 29 is a driver amplifier that drives the optical deflector 8B, and amplifies the output signal of the flip-flop 28 and outputs the amplified signal to the optical deflector 8B as a key modulation signal KS. As a result, the amplification circuit 29 changes the laser beam irradiation position in the inner and outer circumferential directions of the disc master 2 in units of pits. The amplification circuit 29 has its gain set so that the displacement amount is at most 1/50 of the track pitch or less, so that the optical disk apparatus 1 can reproduce the data recorded by the pit string. It is made so as not to damage.
[0039]
Thus, in this embodiment, the master disk 2 exposed in this way is developed and electroformed to create a mother disk, and a stamper is prepared from the mother disk. Further, an optical disc is produced from this stamper in the same manner as a normal compact disc production process.
[0040]
As a result, in this embodiment, the optical data D1 encrypted by the pit string is recorded, and an optical disc is recorded in which the key data KY is recorded by the displacement of each pit P in the inner and outer peripheral directions (see FIG. 3 (E-2)). That is, in a normal compact disc, pits P are sequentially formed on the track center along the track in accordance with the EFM signal S2, and audio data is recorded according to the pit length and the interval between the pits ( FIG. 3 (E-1)). On the other hand, in the optical disc according to this embodiment, the audio data encrypted by the pit length and the interval between the pits is recorded, and the audio data is encrypted by the displacement of the pits P in the inner and outer peripheral directions. The key data KY for canceling the conversion is recorded.
[0041]
FIG. 4 is a block diagram of the optical disc apparatus 30 that reproduces the optical disc 31 thus created. In the optical disk device 30, the spindle motor 32 rotates the optical disk 31 under the condition of a constant linear velocity under the control of the servo circuit 33.
[0042]
The optical pickup 34 irradiates the optical disc 31 with a laser beam and receives the return light by a predetermined light receiving element, and generates a reproduction signal RF whose signal level changes according to the light intensity of the return light on the light receiving surface of the light receiving element. Output. Here, the signal level of the reproduction signal RF changes corresponding to the pits recorded on the optical disk 31.
[0043]
Further, the optical pickup 34 processes the reception result of the return light by a so-called push-pull method, so that the push-pull signal whose signal level changes in accordance with the pit position with respect to the laser beam irradiation position in the inner and outer peripheral directions of the optical disc 31. PP is generated. The optical pickup 34 generates and outputs a focus error signal whose signal level changes according to the focus error amount.
[0044]
In the servo circuit 33, the push-pull signal PP is band-limited to generate a tracking error signal whose signal level changes in accordance with the detrack amount of the laser beam irradiation position with respect to the track center. The pickup 34 is tracking-controlled. The servo circuit 33 controls the focus of the optical pickup 34 with a focus error signal.
[0045]
The high-pass filter (HPF) 35 suppresses the low-frequency component of the push-pull signal PP, so that the laser beam for the track center is changed from the push-pull signal PP whose signal level changes according to the pit position with respect to the laser beam irradiation position. A displacement detection signal HPP whose signal level changes according to the position of the pit relative to the track center is removed by removing the detrack amount component at the irradiation position.
[0046]
The binarization circuit 36 binarizes the reproduction signal RF with a predetermined reference level and creates a binarized signal BD.
[0047]
The PLL circuit 37 reproduces the channel clock CCK of the reproduction signal RF by operating on the basis of the binarized signal BD.
[0048]
The EFM demodulation circuit 38 reproduces the reproduction data corresponding to the EFM modulation signal S2 by sequentially latching the binarized signal BD with reference to the channel clock CCK. Further, the EFM demodulating circuit 38 performs EFM demodulation of the reproduction data, delimits the demodulated data in units of 8 bits with reference to the frame sync, deinterleaves the generated 8-bit unit signal, and performs ECC (Error Correcting Code). Output to the circuit 39.
[0049]
The ECC circuit 39 performs error correction processing on the output data based on the error correction code added to the output data of the EFM demodulation circuit 38, and reproduces and outputs the audio data thus encrypted.
[0050]
The encryption processing circuit 40 decrypts the audio data with the key data KY detected by the key detection circuit 42 and outputs the result.
[0051]
The digital / analog conversion circuit (D / A) 41 performs a digital / analog conversion process on the audio data D1 output from the encryption processing circuit 40, and outputs an audio signal S4 composed of an analog signal.
[0052]
The key detection circuit 42 processes the displacement detection signal HPP on the basis of the channel clock CCK and the binary signal BD, thereby reproducing the key data KY and outputting it to the encryption processing circuit 40.
[0053]
FIG. 5 is a block diagram showing the key detection circuit 42 in detail. In the key detection circuit 42, the subcode detection circuit 52 monitors the binary signal BD with reference to the channel clock CCK, and decodes the subcode information from the binary signal BD. Further, the subcode detection circuit 52 monitors time information in the decoded subcode information, and outputs a 1-second detection pulse SECP in which the signal level rises every time this time information changes by 1 second.
[0054]
The pit detection circuit 54 sequentially latches the binarized signal BD at the timing of the channel clock CCK, and detects the timing at which the pit rises from the binarized signal BD by comparing two consecutive latch results. The pit detection circuit 54 outputs the edge detection signal PT at the timing when the pit rises from the detection result. Similarly, the pit detection circuit 54 detects the timing at which the pit has fallen, and outputs a center detection signal CTP at a substantially central portion of each pit based on the detection result of the timing at which the corresponding pit has risen.
[0055]
The synchronization detection circuit 55 detects the synchronization pattern by sequentially latching the binarized signal BD with reference to the channel clock CCK and determining the continuous logic level. Thereby, as shown in FIG. 6, the synchronization detection circuit 55 sets the set pulse FSET (FIG. 6 (A3), (B) and (D)) in which the signal level rises by one clock cycle at the timing when the synchronization pattern starts, A clear pulse FCLR (FIG. 6C) in which the signal level rises with a delay of one clock cycle from the set pulse FSET is generated and output.
[0056]
Accordingly, in the binarized reproduction signal BD (FIG. 6 (A1) and (A2)), the synchronization detection circuit 55 detects the synchronization pattern by detecting it 98 times per second in a period of 588 clocks. The clear pulse FCLR and the set pulse FSET are output in synchronization with the synchronization pattern.
[0057]
The M series generation circuit 56 initializes the address with reference to the clear pulse FCLR, and then sequentially advances the address by the channel clock CCK to access the built-in read-only memory, and thereby the M generated by the optical disc apparatus 1 M-sequence random number data MX corresponding to the sequence random number data MS is generated.
[0058]
As a result, the key detection circuit 42 reproduces various reference signals necessary for reproducing the key data KY corresponding to the processing in the optical disc apparatus 1.
[0059]
In the key detection circuit 42, an analog / digital conversion circuit 57 performs an analog / digital conversion process on the displacement detection signal HPP based on the channel clock CCK, and outputs an 8-bit digital reproduction signal. The polarity inversion circuit (-1) 58 inverts the polarity of the digital reproduction signal and outputs it.
[0060]
The latch circuit 59 latches the M-sequence random number data MX at the timing of the edge detection signal PT, and thereby, according to the timing corresponding to the processing timing of the exclusive OR circuit 27 in the key modulation circuit 10 described above with reference to FIG. The latched data MX is held until one pit is completed after the M-sequence random number data MX is latched at the timing of pit formation start.
[0061]
The selector 60 selects and outputs a digital signal directly input from the analog-digital conversion circuit 57 and a digital signal obtained by inverting the polarity input from the polarity inversion circuit 58 according to the logic level of the output data MZ of the latch circuit 59. To do. That is, the selector 60 selects and outputs a directly input digital signal when the output data MZ of the latch circuit 59 is logic 1, and conversely, when the output data MZ of the latch circuit 59 is logic 0, the polarity is selected. Select the inverted digital signal. As a result, the selector 60 reproduces the logical level of the key data KY (KD) modulated by the M-sequence random number data MS with the multi-value data, and outputs the reproduction data RX with the multi-value data.
[0062]
The adder 62 is a 16-bit digital adder that adds the reproduction data RX and the output data AX of the accumulator (ACU) 63 and outputs the result. The accumulator 63 is composed of a 16-bit memory that holds the output data of the adder 62, and forms a cumulative adder together with the adder 62 by feeding back the held data to the adder 62. That is, the accumulator 63 clears the content held by the clear pulse FCLR, and then cumulatively adds the output data of the adder 62 in synchronization with the output signal CTP of the pit detection circuit 54.
[0063]
As a result, the adder 62 and the accumulator 63 add or subtract the displacement amount of the pit detected at the center of each pit according to the M-sequence random number data MS and accumulate, and repeat this accumulation operation in one frame period. Has been made.
[0064]
The binarization circuit 64 binarizes the output data AX of the accumulator 63 with a predetermined reference value and outputs the binarized data. Accordingly, the binarization circuit 64 converts the reproduction data RX of the multi-value key data KY (KD) reproduced by the selector 60 into binary data.
[0065]
The shift register (SR) 65 is a 98-bit shift register, and sequentially takes and transfers the binarized data output from the binarization circuit 64 at the timing when the set pulse FSET rises.
[0066]
The flip-flop (F / F) 66 fetches and holds the output data of the shift register 65 in bit parallel at the timing of the 1-second detection pulse SECP. As a result, in the key detection circuit 42, the data KD composed of the key data KY and the fixed value data KZ is held in the flip-flop 66. The key detection circuit 42 selectively outputs predetermined bits of the flip-flop 66 to supply the key data KY to the encryption processing circuit 40 to release the encryption of the audio data.
[0067]
(2) Operation of the embodiment
In the above configuration, in the manufacturing process of the optical disc 31 according to this embodiment, the master disc 2 is exposed by the optical disc apparatus 1 (FIG. 1), and this master disc 2 is developed and electroformed to produce a mother disc. A stamper and an optical disc are created from this mother disc.
[0068]
In the exposure of the disc master 2, in the optical disc apparatus 1, the audio data D1 output from the digital audio tape recorder 3 is input to the encryption circuit 15, where it is encrypted with predetermined key data KY. As a result, the audio data D1 is processed so that it cannot be auditioned unless the key data KY is used, and the subsequent modulation circuit 9 is processed in the same manner as the processing in a normal compact disc and converted into the EFM signal S2.
[0069]
In the optical disk apparatus 1, the laser beam L1 is controlled to be turned on / off by the EFM signal S2, and the laser beam L2 controlled to be turned on / off is sequentially condensed from the inner peripheral side to the outer peripheral side of the rotating disk master 2, thereby A spiral track is formed on the outer peripheral side, and audio data D1 encrypted by a pit string is recorded along this track.
[0070]
In this manner, while the audio data D1 is recorded by the pit string, in the optical disc apparatus 1, the key modulation circuit 10 generates the key modulation signal KS by modulating the key data KY with difficulty in decoding, and this key modulation. The optical deflector 8B is driven by the signal KS and the condensing position of the laser beam L3 is displaced in the inner and outer peripheral directions of the disc master 2, whereby the key data KY is recorded by the displacement in the inner and outer peripheral directions of the pits.
[0071]
Thus, in this embodiment, it is possible to provide the audio data D1 encrypted so that it cannot be auditioned without using the key data KY, and the key data KY by a single recording medium.
[0072]
The maximum displacement of the pits formed in this way is set to 1/50 of the track pitch, which makes it easy to displace the pits even when the information recording surface is observed with a microscope. So that it can not be found. Accordingly, it is possible to prevent illegal copying by making it difficult to analyze the displacement of the pits.
[0073]
In addition, since the amount of displacement is small, the reproduction signal can be processed with sufficient phase margin and amplitude margin in reproducing the audio data D1 recorded by the pit train, and thus the audio data recorded by the pit train can be reliably reproduced. it can. Incidentally, such a displacement of the pits in the inner and outer circumferential directions may affect the tracking control. However, when the amount of displacement is small to the extent according to this embodiment, the data recorded by the pit row can be reproduced with a tracking accuracy sufficient for practical use.
[0074]
That is, the key data KY (FIG. 2) has a meaning in the DES code 54-bit key data KY, assuming that 98 bits are allocated per second in the compact disc and 1-bit data is allocated to each frame. The data KZ having no fixed 44 bits is added and set in the data selector 24.
[0075]
The key data KY (KD) set in this way is 1 bit per frame by the detection of the synchronization pattern in the synchronization detection circuit 21 and the detection result SECP in the 1 second period detected by the subcode detection circuit 22. Is output from the data selector 24 so as to circulate in one second.
[0076]
Simultaneously and in parallel, in the M-sequence generation circuit 25, random number data MS, which is a binary number sequence in which logic 1 and logic 0 are generated with equal probability, is synchronized with the clock CK and the detection result FCK of the synchronization pattern. Is generated so as to be repeated for each frame.
[0077]
The key data KY (KD) is output from the data selector 24, and the exclusive OR with the random number data MS is obtained in the exclusive OR circuit 27, thereby being modulated by the random number data MS. At this time, since the random number data in the MS is a binary number sequence in which logic 1 and logic 0 are generated with equal probability, in the output data of the exclusive OR circuit 27 that is modulated, the logic 1 is almost equal to logic 1. A logical 0 will occur with equal probability.
[0078]
In the key modulation circuit 10, the output data MS1 generated in this way is latched at the rising edge of the EFM signal S2 in the flip-flop 28, so that one bit of the output data MS1 is generated in each pit formed on the disk master 2. Is selectively allocated, and the converging position of the laser beam L3 is displaced in the inner and outer peripheral directions of the disc master 2 by the optical deflector 8B in accordance with the 1-bit logic level. Recorded by circumferential displacement.
[0079]
At this time, in this embodiment, the key data KY (KD) is output from the data selector 24 at a cycle of 1 bit per frame, and the key data KY (KD) is modulated by the random number data MS and the pits P are displaced. As a result, in the optical disc, the pits P are irregularly displaced in the inner and outer circumferential directions.
[0080]
Accordingly, in this embodiment, each bit of the key data KY can be distributed and recorded in a plurality of pits to make it difficult to find the key data KY recorded by the displacement of the pits. That is, even when the information recording surface is observed with a microscope or the like, the pit string is observed as if it was modulated by noise, and the key data KY can be difficult to find by such visual observation. Thus, in this case, since one bit of the key data KY is assigned to the 588 channel clock, at least one bit of the key data KY is distributed and recorded in 50 or more pits.
[0081]
Further, at this time, the logic 1 and the logic 0 are generated with equal probability in the random number data MS, so that the displacement of the pits formed in this way is also the displacement toward the inner periphery and the displacement toward the outer periphery with respect to the track center. Will occur with almost equal probability. As a result, since this displacement is minute, even if various signals obtained from the optical pickup are observed, it is observed as if noise is mixed, and the presence or absence of key data KY is also confirmed by such waveform observation. It can be difficult to find.
[0082]
On the other hand, the pit displacement does not include an offset component which is a direct current component. Further, by latching by the flip-flop 28 and setting the displacement for each pit, when detecting the displacement of this pit, the higher frequency side than the push-pull signal PP for detecting the tracking error signal is detected. Although it is due to the SN that has been extracted and significantly deteriorated, the displacement can be easily detected. As a result, in this optical disc, the key data KY can be reproduced with a simple configuration that can be reproduced by an optical pickup having a conventional configuration, and illegal copying can be prevented.
[0083]
That is, in the optical disk device 30 of the optical disk 31 thus created (FIG. 4), the reproduction signal RF is binarized by the binarizing circuit 36 and then the EFM demodulating circuit 38, as in the conventional compact disk player. The error data is processed by the subsequent ECC circuit 39, whereby the encrypted audio data is reproduced. In the subsequent encryption processing circuit 40, the encryption is canceled by the separately acquired key data KY, so that the audio signal recorded by the pit string can be auditioned via the digital-analog conversion circuit 41.
[0084]
Further, in the optical disc apparatus 30, the push-pull signal PP obtained from the optical pickup 34 is band-limited by the high pass filter 35, so that the signal level changes according to the displacement amount in the inner and outer peripheral directions of the pits with a simple configuration. A detection signal HPP is detected.
[0085]
In the optical disk device 30, the displacement detection signal HPP is processed by the key detection circuit 42 to reproduce the key data KY.
[0086]
That is, in the key detection circuit 42 (FIG. 5), the displacement detection signal HPP is converted into a digital signal at a channel clock period by the analog-digital conversion circuit 57, and the polarity inversion circuit 58 generates a digital signal whose polarity is inverted. The
[0087]
These two systems of digital signals are selectively added by the output data MZ generated by latching the random number data MX generated on the basis of the synchronization pattern of the binary signal BD by the latch circuit 59 at the timing of the pits. Is input to the counter 62 and is cumulatively added with reference to the detection result FCLR of the synchronization pattern.
[0088]
That is, during recording, the output data of the analog-digital conversion circuit 57 is added or subtracted in accordance with the logic level of the output data of the exclusive OR circuit 27 (FIG. 2) at the rising timing of the EFM signal S2, and the addition is performed. As a result, the accumulated value AX as the subtraction result is accumulated in the accumulator 63 in the frame period. Further, at the timing when the synchronization pattern starts, the binary identification result of the accumulated value AX of the accumulator 63 is taken into the shift register 65, whereby the key data KY is demodulated.
[0089]
As a result, in the displacement detection signal HPP obtained from each pit, the displacement detection signal HPP is accumulated for one frame in this way even if the SN ratio is significantly deteriorated due to the minute displacement. By performing binary identification, the key data KY can be reproduced by performing binary identification with a high S / N ratio. This makes it possible to reliably reproduce the key data KY recorded difficult to find.
[0090]
In the key detection circuit 42, when the signal level of the displacement detection signal HPP is accumulated in the accumulator 63, the addition result of the adder 62 is taken in and accumulated at the timing of the central portion of each pit. As a result, the key detection circuit 42 accumulates the signal level at a timing when the signal level of the displacement detection signal HPP is sufficiently stable, and the detection accuracy is further improved.
[0091]
Accordingly, in the case of illegal copying, it may be considered that an illegally copied optical disk is produced by controlling on / off of the laser beam by the binary signal BD output from the binarization circuit 36. However, in this illegal copy, it is difficult to record the key data KY depending on the displacement of the pits. As a result, it is difficult to create an illegal copy of the optical disc 31 according to this embodiment.
[0092]
In addition, when the optical disk by illegal copying in which only the pit row is copied in this way is reproduced by the optical disk apparatus according to this embodiment, the key data KY due to the pit displacement is lost and encrypted. Audio signals such as noise will be output, making it difficult to enjoy music normally. As a result, the value of the optical disk by illegal copying can be significantly reduced, and as a result, the spread of illegal copying can be prevented.
[0093]
As a result, in this embodiment, the key data that does not affect the reproduction of the audio data by the pit row, can be reproduced by the optical pickup that reproduces the audio data, and is difficult to copy by illegal copying. Can be recorded.
[0094]
(3) Effects of the embodiment
According to the above configuration, by recording the key data by displacing the pits in the inner and outer circumferential directions, the optical pickup that reproduces the audio data does not affect the reproduction of the audio data string by the pit string. The key data can be recorded so as to be reproducible and difficult to copy by illegal copying. Therefore, the audio data encrypted with the key data can be recorded as a pit string, and illegal copying can be effectively prevented.
[0095]
At this time, by modulating and recording the key data with the binary number sequence, it is possible to make it difficult to find the recording of the key data due to the pit displacement, and to effectively prevent illegal copying.
[0096]
Further, by applying an M-sequence random number in which logic 1 and logic 0 are generated with equal probability to this binary sequence, it is observed as if noise is mixed in the output signal of the optical pickup. It is possible to prevent illegal copying by making it difficult to find key data.
[0097]
In addition, it is possible to reliably reproduce the key data recorded with extremely small displacement by setting at least 50 pits so that one bit of the key data corresponds.
[0098]
That is, by accumulating the signal level of the displacement detection signal on the basis of the binary series logic level, the key data recorded with a small displacement can be reliably reproduced.
[0099]
Also, by setting the pit displacement amount in the inner and outer circumferential directions with reference to the track center as 1/50 of the track pitch, it is possible to make it difficult to find the key data recorded by this pit displacement.
[0100]
(4) Other embodiments
In the above-described embodiment, the case where one bit of key data is assigned to one frame has been described. However, the present invention is not limited to this, and a plurality of bits may be assigned to one frame. One bit of key data may be assigned to a plurality of frames. Further, instead of assigning key data bits based on audio data frames recorded by pit rows, one bit of key data may be assigned based on the number of pits.
[0101]
In the above-described embodiment, one bit of key data is allocated to one frame, so that one bit of key data is distributed and recorded in 50 or more pits. However, the number of pits to which 1 bit is allocated can be variously set as needed. By the way, according to the experimental results, it is possible to reproduce key data with a practically sufficient SN ratio by assigning one bit of key data to 20 or more pits.
[0102]
In the above-described embodiment, the case where the fixed bit data having no meaning is added to the key data and recorded is described. However, the present invention is not limited to this, and an error correction code is added to the key data. You may make it record, You may make it add and record the data of copyright.
[0103]
In the above-described embodiment, the case where the data encrypted by the pit string is recorded and the key data necessary for the decryption is recorded by the displacement of the pits in the inner and outer peripheral directions has been described. The present invention is not limited to this, and can be widely applied to recording various data such as recording identification data such as whether or not copying is possible instead of key data.
[0104]
In the above-described embodiment, the case where the accumulator binary value is identified to reproduce the key data has been described. However, the present invention is not limited to this, and the accumulated value is reproduced by multi-value identification. It may be. In this way, multivalued data can be recorded by pit displacement.
[0105]
In the above-described embodiment, the case of recording a digital audio signal by EFM modulation has been described. However, the present invention is not limited to this, and various other types such as 1-7 modulation, 8-16, and 2-7 modulation are used. It can be widely applied to modulation.
[0106]
In the above-described embodiment, the case where key data is recorded on the entire surface of the optical disk has been described. However, the present invention is not limited to this, and may be recorded in a limited area such as a lead-in area. .
[0107]
In the above-described embodiment, the case where desired data is recorded by the pit row has been described. However, the present invention is not limited to this, and can be widely applied to the case where desired data is recorded by the mark row. .
[0108]
Further, in the above-described embodiment, the case where the present invention is applied to the optical disk for recording audio data and the peripheral device to record the audio signal has been described. However, the present invention is not limited to this, and various video disks and the like can be used. The present invention can be widely applied to optical discs and peripheral devices thereof.
[0109]
【The invention's effect】
As described above, according to the present invention, the secondary data such as the key data is recorded by displacing the pits in the inner and outer peripheral directions of the optical disk, so that the data string reproduction by the pit string is not affected at all. Thus, it is possible to record various data that can be reproduced by an optical pickup that reproduces the data string and that it is difficult to copy by illegal copying.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an optical disc apparatus used for producing an optical disc according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a key modulation circuit of the optical disc apparatus of FIG.
FIG. 3 is a time chart for explaining the operation of the key modulation circuit of FIG. 2;
4 is a block diagram showing an optical disk apparatus for reproducing an optical disk created by the optical disk apparatus of FIG. 1. FIG.
5 is a block diagram showing a key detection circuit of the optical disc apparatus of FIG. 4. FIG.
6 is a time chart for explaining the operation of the key detection circuit of FIG. 5;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical disk apparatus, 2 ... Disc original disc, 10 ... Key modulation circuit, 21, 55 ... Synchronization detection circuit, 22, 52 ... Subcode detection circuit, 25 ... M series generation circuit, 30 ... Optical disk Device, 31 ... optical disc, 42 ... key detection circuit

Claims (30)

Main modulation signal generating means for generating a main modulation signal according to main data;
A recording beam irradiation means for forming a pit row or a mark row on the disc by irradiation of a recording beam in accordance with the main modulation signal;
Binary number generation means for generating a binary number sequence that is a pseudo-random number, assigning a plurality of bits of the binary number sequence to one bit of the sub data used for copyright protection of the main data, Sub modulation signal generating means for generating a sub modulation signal in which a plurality of bits correspond to one bit of the sub data by processing with the binary number sequence ;
By displacing the irradiation position of the recording beam in the inner circumferential direction or the outer circumferential direction of the disc in accordance with the secondary modulation signal with reference to the track center of the track by the pit row or mark row, A position displacing means for allocating one bit of data to a plurality of pits or marks and displacing the pits or marks in an inner circumferential direction or an outer circumferential direction of the disc by a predetermined amount according to the sub data and the binary number sequence;
The predetermined amount is
In the push-pull signal obtained at the time of reproduction, the signal level due to the displacement is a minute amount that is lower than the noise level,
It is a displacement that can reproduce the 1 bit by integrating the signal level of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub data is assigned.
Disk recording device comprising a call. The sub modulation signal generating means includes
Timing detection means for detecting the timing of the edge of the pit or mark and outputting a timing detection result ;
Based on the previous SL binary sequences and the timing detection result, the disc recording apparatus according to claim 1, characterized in that it comprises a modulating means from sub data to generate a modulated signal of the sub. The binary sequence is
The disk recording apparatus according to claim 2, wherein the disk recording apparatus is an M-sequence random number. The main modulation signal generating means includes:
The disk recording apparatus according to claim 1, wherein the main modulation signal is generated by encrypting the main data with the sub data. The main modulation signal generating means includes:
The disk recording apparatus according to claim 1, wherein the main modulation signal is generated so that the light amount of the laser beam is switched at a cycle that is an integral multiple of a predetermined basic cycle. Wherein the plurality of pits or marks 1 bit of the sub data is allocated, the disk recording apparatus according to claim 1, wherein the Ru 20 or more of the pits or marks der. The disk recording apparatus according to claim 1, wherein the sub data is key data used for decrypting the main data. Depending on the main data, generate the main modulation signal,
A pit row or mark row is formed on the disc by irradiation of a recording beam according to the main modulation signal,
By assigning a plurality of bits of a binary number sequence, which is a pseudo-random number, to one bit of sub data used for copyright protection of the main data, and processing the sub data with the binary number sequence, 1 bit of the sub data To generate a secondary modulation signal corresponding to a plurality of bits ,
By displacing the irradiation position of the recording beam in the inner circumferential direction or the outer circumferential direction of the disc in accordance with the secondary modulation signal with reference to the track center of the track by the pit row or mark row , 1 bit of data is assigned to a plurality of pits or marks, and the pits or marks are displaced by a predetermined amount in the inner or outer circumferential direction of the disc according to the sub data and the binary number sequence ,
The predetermined amount is
In the push-pull signal obtained at the time of reproduction, the signal level due to the displacement is a minute amount that is lower than the noise level,
A disc recording method characterized in that the signal level of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub data is allocated is integrated, and the displacement is a reproducible amount of the 1 bit . 9. The disk recording method according to claim 8, wherein the sub modulation signal is generated from the sub data based on a timing corresponding to an edge of the pit or mark and a predetermined binary sequence. The disk recording method according to claim 9, wherein the binary number sequence is an M-sequence random number. The disk recording method according to claim 8, wherein the main modulation signal is generated by encrypting the main data with the sub data. The disk recording method according to claim 8, wherein the main modulation signal is generated so that the light amount of the laser beam is switched at a cycle that is an integral multiple of a predetermined basic cycle. Wherein the plurality of pits or marks 1 bit of the sub data is allocated, recording method for a disk according to claim 8, wherein the Ru 20 or more of the pits or marks der. The disk recording method according to claim 8, wherein the sub data is key data used for decrypting the main data. In an optical disc in which pit rows or mark rows are formed along spiral or concentric tracks,
Main data is recorded by the length of the pits or marks in the direction along the track and the interval between the pits or the interval between the marks,
The sub-data generated by assigning a plurality of bits of a binary number sequence that is a pseudo-random number to one bit of the sub-data used for copyright protection of the main data, and processing the sub-data with the binary number sequence One bit of the sub data is assigned to a plurality of pits or marks in accordance with a sub modulation signal corresponding to a plurality of bits corresponding to one bit of the track in the inner or outer circumferential direction with reference to the track center of the track. wherein in the pits or marks by the displacement of the sub-data and a predetermined amount in accordance with the binary sequences, pre SL sub data is recorded,
The predetermined amount is
In the push-pull signal obtained at the time of reproduction, the signal level due to the displacement is a minute amount that is lower than the noise level,
An optical disc characterized by integrating a signal level of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub-data is assigned, so that the 1 bit can be reproduced . The optical disc according to claim 15 , wherein the binary number sequence is an M-sequence random number. 16. The optical disc according to claim 15, wherein the main data is recorded by being encrypted with the sub data. The optical disk of claim 15, wherein the plurality of pits or marks 1 bit of the sub data is allocated, and wherein the Ru 20 or more of the pits or marks der. The optical disk according to claim 15, wherein the displacement of the pit or mark in the inner circumferential direction or the outer circumferential direction with respect to the track center is set to 1/50 or less of the track pitch. 16. The optical disc according to claim 15, wherein the sub data is key data used for decrypting the main data. Reproduction signal detecting means for detecting a reproduction signal whose signal level changes according to a pit row or a mark row formed on the optical disc from return light obtained by irradiating the optical disc with a laser beam;
Main demodulating means for binaryly identifying the reproduction signal and reproducing main data recorded by the pit string or mark string;
Displacement detecting means for outputting a push-pull signal whose signal level changes according to the displacement of the pits or marks in the inner and outer circumferential directions with reference to the track center;
By processing the push-pull signal with reference to the reproduction signal, the main data recorded by a predetermined amount of displacement of the pit or mark in the inner or outer circumferential direction with respect to the track center is used. and a sub-demodulating means for reproducing the sub data to be used for copyright protection,
The secondary demodulating means includes:
Binary sequence generation means for generating a binary sequence that is a pseudo-random number;
Integrating means for integrating the signal level of the push-pull signal on the basis of the logic level of the binary sequence;
Integration result processing means for processing the integration result and detecting the sub-data,
The predetermined amount is
In the push-pull signal obtained at the time of reproduction, the signal level due to the displacement is a minute amount that is lower than the noise level,
It is a displacement that can reproduce the 1 bit by integrating the signal level of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub data is assigned.
Optical disk reproducing apparatus, wherein the this. The optical disk reproducing apparatus according to claim 21 , wherein the binary number sequence is an M-sequence random number. The main demodulation means is:
The optical disk reproducing apparatus according to claim 21 , wherein the sub-data is output after being decrypted with the main data. From the return light obtained by irradiating the optical disk with a laser beam, a main data reproduction step of reproducing main data recorded by the pit row or mark row ;
A push-pull signal generating step for generating a push-pull signal whose signal level changes in accordance with the displacement of the pits or marks in the inner and outer peripheral directions with respect to the track center;
By the signal processing of the push-pull signal, sub-data used for copyright protection of the main data recorded by a predetermined amount of displacement of the pit or mark in the inner circumferential direction or the outer circumferential direction with respect to the track center. A secondary demodulation step to reproduce,
The secondary demodulation step comprises:
A binary sequence generation step for generating a binary sequence that is a pseudo-random number;
An integration step of integrating the signal level of the push-pull signal with reference to the logic level of the binary number sequence;
An integration result processing means for processing the integration result of the integration step and detecting the sub data;
The predetermined amount is
In the push-pull signal obtained at the time of reproduction, the signal level due to the displacement is a minute amount that is lower than the noise level,
A method of reproducing an optical disk , comprising integrating a signal level of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub data is allocated, and a displacement amount capable of reproducing the 1 bit . The disk according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the disk is a disk master used for production of an optical disk. Recording device. 26. An optical disc produced by the disc master on which the main data and sub data are recorded by the disc recording apparatus according to claim 25 . The disk according to claim 8, 9, 10, 11, 12, 13, or 14, wherein the disk is a disk master used for production of an optical disk. Recording method. 28. An optical disc produced by the disc master on which the main data and sub data are recorded by the disc recording method of claim 27 . A signal processing circuit used in a disc production apparatus for exposing a disc master,
The disk production apparatus is
A recording beam irradiation means for forming a pit row or a mark row on the disc master by irradiation of a recording beam in accordance with a main modulation signal;
Position displacement means for displacing the irradiation position of the recording beam by a predetermined amount in the inner circumferential direction or the outer circumferential direction of the disk in accordance with a secondary modulation signal;
The signal processing circuit includes:
Main modulation signal generating means for generating the main modulation signal according to main data;
Sub modulation signal generation means for generating the sub modulation signal based on sub data used for copyright protection of the main data, the sub modulation signal generation means,
A binary sequence generating means for generating a binary sequence that is a pseudo-random number, wherein a plurality of bits of the binary sequence are assigned to one bit of the sub-data, and a plurality of bits correspond to one bit of the sub-data In addition, one bit of the sub data is assigned to a plurality of pits or marks, and the pits or marks are displaced by a predetermined amount in the inner or outer circumferential direction of the disc according to the sub data and the binary number series. Generating the secondary modulation signal;
The predetermined amount is
In the push-pull signal obtained at the time of reproduction, the signal level due to the displacement is a minute amount that is lower than the noise level,
A signal processing circuit characterized by integrating a signal level of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub-data is assigned, to obtain a displacement that can reproduce the 1 bit . A signal processing circuit used in an optical disk reproducing device,
The optical disc playback apparatus comprises:
From the return light obtained by irradiating the optical disc with a laser beam, a reproduction signal whose signal level changes according to a pit row or a mark row formed on the optical disc, and the inner and outer circumferential directions with reference to the track center. It has an optical pickup that outputs a push-pull signal whose signal level changes according to the displacement of the pit or mark,
The signal processing circuit includes:
Main demodulating means for binaryly identifying the reproduction signal and reproducing main data recorded by the pit string or mark string;
By performing signal processing on the push-pull signal with reference to the reproduction signal, the main data recorded by a predetermined amount of displacement of the pit or mark in the inner circumferential direction or outer circumferential direction with respect to the track center is used. A secondary demodulation means for reproducing secondary data used for copyright protection,
The secondary demodulating means includes:
A binary sequence generation step for generating a binary sequence that is a pseudo-random number;
An integration step of integrating the signal level of the push-pull signal with reference to the logic level of the binary number sequence;
An integration result processing means for processing the integration result of the integration step and detecting the sub data;
The predetermined amount is
In the push-pull signal obtained at the time of reproduction, the signal level due to the displacement is a minute amount that is lower than the noise level,
It is a displacement that can reproduce the 1 bit by integrating the signal level of the push-pull signal in a plurality of pits or marks to which 1 bit of the sub data is assigned.
Signal processing circuit, wherein the this.

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