JP3770272B2 - Optical recording medium and optical disk reproducing apparatus - Google Patents

Description

  The present invention relates to an optical disk, and more particularly to an optical disk having a copy prevention function, a method of manufacturing an optical disk master for manufacturing the optical disk, and a playback apparatus for the optical disk.

  In general, an optical disk is manufactured by producing a master, a mother, and a stamper from a master, and using this stamper to duplicate a large amount by injection molding. In some cases, the stamper is made directly from the master. In general, optical disc masters are coated with a photoresist on a glass substrate whose surface has been polished, and this photoresist is exposed using a laser beam whose intensity is modulated by an information signal to be recorded, and then developed to support the sensitivity. It is produced by forming the uneven signal or groove or the uneven signal and groove. Hereinafter, the uneven signal or groove or the uneven signal and groove are collectively referred to as a signal pit.

  FIG. 18 shows a block diagram of a master recording apparatus. A focus control laser optical system and a beam expander of a recording laser optical system used in exposing the photoresist 5a on the glass plate 5 as a master disk with laser light are omitted. In FIG. 18, 1 is a recording laser, 2 is an optical modulator, 3 is a mirror, 4 is a lens actuator, 5 is a glass plate coated with a photoresist 5a, 6 is a spindle motor, 7 is a signal source, and 8 is a recording equalizer. It is.

  The signal generated by the signal source 7 is changed in pulse width by a certain amount by the recording equalizer 8, input to the optical modulator 2, and intensity-modulates the laser light emitted from the recording laser 1. The intensity-modulated laser light passes through the mirror 3 and exposes the photoresist 5a on the glass plate 5 through the lens whose focus is controlled by the lens actuator 4. In this way, signal pits are formed in the photoresist 5a. A stamper is manufactured as described above from the master disc formed in this manner, and an optical disc having information recorded on the master disc is manufactured by this stamper.

  The optical disk reproducing device condenses a semiconductor laser on the signal surface of the optical disk, converts the intensity of reflected light from the signal surface into an electrical signal with a photodiode or the like (this signal is called an RF signal), shapes the waveform, The digital signal is demodulated and digital signal processing is performed to reproduce the original signal.

  FIG. 19 shows a block diagram of a conventional optical disk reproducing apparatus. In FIG. 19, 9 is an optical disk, 10 is an optical pickup, 11 is a spindle motor, 12 is an analog waveform shaping unit, 13 is a digital demodulation unit, 14 is a digital signal processing unit, 15 is a control unit, 16 is a focus servo unit, 17 Is a tracking servo section, and 18 is a rotation servo section.

  A signal immediately before being demodulated into an RF signal or a digital signal is generally called an eye pattern. An example of an eye pattern is shown in waveform (9) in FIG. Although the center of the eye pattern and the center of the amplitude may slightly deviate (referred to as asymmetry), the eye pattern center can be automatically detected when demodulating to a digital signal if there is a certain deviation. Normally, in order to reduce asymmetry during reproduction, correction is applied to the duty of a signal recorded on the master when the master is created. This is called record equalization. The optimum recording equalization amount varies depending on recording power, development conditions, reproduction conditions, and the like.

  Now, a logical copy prohibition signal is defined in the conventional optical disc. Accordingly, the optical disk on which the anti-duplication flag signal is recorded is configured to prevent the recording apparatus from recording because the anti-duplication flag signal is detected at the time of recording (for example, Patent Document 1).

However, a reproducing device for a ROM disk such as a CD has not conventionally had a function for preventing or prohibiting reproduction of illegally copied material. This is because an optical disk medium that can be written only once and can be played back by a normal playback device has been put on the market, but if you purchase this optical disk medium and duplicate it from a commercially available regular optical disk, This is because there is almost no need to take measures against illegal duplication because the price is higher than the purchase, or the writing device for duplication is expensive and not widespread.
JP-A-4-82039

  However, in recent years, software such as games has been recorded on an optical disc, and a commercially available optical disc on which such game software is recorded has a high selling price due to the added value of the software. On the other hand, the price of optical disc media that can be written only once and can be played back by a normal playback device has been decreasing year by year. In such a situation, it is cheaper to duplicate an optical disc that has a relatively high selling price. A situation has emerged. Under such circumstances, anti-duplication technology has been demanded.

  The present invention relates to an optical disc, and more particularly, to provide an optical disc having an anti-duplication function, a method of manufacturing an optical disc master for manufacturing the optical disc, and a reproducing apparatus for the optical disc.

  The present invention provides the above-described object by providing an area in which a signal in which the center of the eye pattern is largely shifted from the center of amplitude is recorded on the optical disc after the signal of the fixed pattern, and after detecting the signal of the fixed pattern in the reproduction apparatus, This is achieved by adding a function of changing a threshold value when demodulating a signal into a digital signal and a function of stopping reproduction unless a signal in which the center of the eye pattern is largely shifted from the center of amplitude is reproduced.

  The signal demodulated digitally and reproduced by the reproduction device from the area where the signal in which the center of the eye pattern is greatly shifted from the center of the amplitude is recorded is a regular signal, and when the demodulated signal is recorded on a recordable optical disc medium, When reproduced, the eye pattern is recorded so that the center of the eye pattern is approximately at the center of the amplitude. For this reason, if the playback device changes the threshold value when demodulating the RF signal into a digital signal and plays back, it is not played back as a regular signal, and playback stops, so the copied disc cannot be played back. Unauthorized duplication can be prevented.

  The optical recording medium, the optical disc reproducing apparatus, and the optical disc reproducing method of the present invention provide an optical recording medium such as an optical disc provided with an area in which a signal in which the center of the eye pattern is greatly shifted from the center of amplitude is recorded after a predetermined pattern of signal. After detecting a signal with a certain pattern in the device, a signal in which the center of the eye pattern is greatly shifted from the center of the amplitude is reproduced by intentionally applying an offset voltage to the threshold when demodulating the RF signal into a digital signal. If the offset signal is not reproduced, a function for stopping reproduction is added.

  Also, the signal demodulated digitally and reproduced by the playback device from the area where the signal where the center of the eye pattern is greatly shifted from the center of the amplitude is recorded is a normal signal, and the demodulated signal is recorded on a recordable optical disc medium. Then, the recording is performed such that the center of the eye pattern is substantially at the center of amplitude when reproduced. For this reason, if the playback device adds an offset to the slice level when demodulating the RF signal into a digital signal and plays it, it will not be played back as a normal signal, and playback will stop, so the copied disc cannot be played back. Unauthorized duplication can be prevented.

  Furthermore, according to the method for producing an optical disc master of the present invention, a master for producing an optical disc having the above-described characteristics can be easily obtained, so that the optical disc can be produced in large quantities and at low cost by molding.

  Hereinafter, the present invention will be described in detail together with an embodiment thereof. In the present invention, a special copy protection signal different from usual is mixed into a recording signal when creating a master disc of an optical ROM disk such as a CD to create a special master disc to prevent duplication. This special copy protection signal is expressed as a CP signal.

  As shown in FIG. 6, in the optical disc of the present invention, after the offset CP signal arrangement information signal of a specific pattern, the signal 24 a to 24 d with the duty ratio sufficiently shifted from the center of the amplitude by a predetermined magnitude after the center of the eye pattern. An area in which 24 g is recorded is provided. In addition, since the CP signal preceding signals 26a to 26g having a specific pattern are provided, the preceding signal recording area is formed after the center of the eye pattern is shifted by a predetermined amount of offset from the center of the amplitude. Serves as a signal.

  FIG. 1 shows a block diagram of an optical disk reproducing apparatus according to the present embodiment. In FIG. 1, 9 is an optical disk, 10 is an optical pickup, 11 is a spindle motor, 12 is an analog waveform shaping unit, 14 is a digital signal processing unit, 16 is a focus servo unit, 17 is a tracking servo unit, 18 is a rotation servo unit, 19 is a digital demodulator that can change the threshold value when demodulating the RF signal into a digital signal, and 20 is the threshold value that is automatically or offset when the reproduction of the offset signal arrangement information signal of a specific pattern is detected. This is a controller that controls the digital demodulator 19 so as to change in advance by the amount VsR.

  As shown in FIG. 1, in the optical disk reproducing apparatus of the present embodiment, after the specific pattern, CP signal arrangement information 25 and CP signal preceding signals 26a to 26g shown in FIG. , Means for changing the threshold value Vs of the level slicer 28 when demodulating the RF signal into a digital signal by an offset amount VsR corresponding to the predetermined amount, and the center of the eye pattern from the center of the amplitude to the predetermined amount When the offset amount VsR signal shifted by this amount is not correctly reproduced, a copy discretion judgment is made and a stop means for stopping the reproduction or program operation is provided.

  The optical disk 9 is rotated by a spindle motor 11. A semiconductor laser is focused on the signal surface of the optical disk 9 by the optical pickup 10, and the intensity of the reflected light from the signal surface is converted into an electric signal by a photodiode or the like to obtain an RF signal. The optical pickup 10 is controlled by the focus servo unit 16 so that the signal surface of the optical disk 9 is always in focus, and the tracking servo unit 17 controls the signal track so that the focus of the semiconductor laser follows. The RF signal is waveform-shaped by the analog waveform shaping unit 12 to become a square wave, demodulated into a digital signal by the digital demodulation unit 19, and digital signal processed by the digital signal processing unit 14 to reproduce the original signal.

  An example of an eye pattern in a normal recorded area where the center of the eye pattern is near the center of the amplitude and no offset voltage is generated is shown in the waveform 9 of FIG. The vertical axis in the figure indicates the amount of reflected light, and the upper side indicates the amount of light. An example of an eye pattern in a region where a signal in which the center of the eye pattern is shifted from the center of the amplitude by a sufficiently large appropriate offset voltage is recorded is shown in a waveform 9 of FIG.

  The control unit 20 controls the movement of the entire reproducing apparatus, and uses the reproduced signal to determine the threshold value when the digital demodulating unit 19 demodulates, that is, the slice value Vs, as the eye pattern center offset voltage in the recording signal. A command is given to change in a short time in response to.

  In the optical disk 9 in the present embodiment, as shown in FIG. 6, there is provided an area in which a signal in which the center of the eye pattern is appropriately shifted from the center of the amplitude by a desired amount is recorded. The optical disc 9 has an arrangement table 25 indicating the arrangement state of the offset CP signal in a region where normal recording is performed so that the center of the eye pattern is near a center of a certain range of amplitude, and the CP signal preceding the specific pattern. The signal is recorded.

  When the offset signal arrangement information 25 and the preceding signal of this specific pattern are reproduced, the optical disc reproducing apparatus of the present embodiment intentionally greatly shifts the center of the eye pattern after the specific pattern based on the offset signal arrangement information. Assuming that the offset CP signal 24 is recorded, an offset correction voltage is applied to the feedback loop 31a of the automatic correction slicer 31 when demodulating the RF signal of FIG. In addition, the slice level is instantaneously changed following the change in the center of the eye pattern. Thus, there is an effect that it is possible to cope with a change in offset voltage faster than the response speed of the auto level slicer.

  In this manner, an area in which a signal in which the center of the eye pattern is largely shifted from the center of the amplitude is recorded following the signal of the specific pattern is reproduced. In reproduction of this area, the threshold value VsR of the level slicer when demodulating the RF signal of the reproduction apparatus into a digital signal is changed in advance by the offset voltage ΔVs according to the offset signal arrangement information. Accordingly, it is possible to correctly reproduce an area in which a signal in which the center of the eye pattern is greatly shifted from the center of the amplitude is recorded.

  In order to reproduce the area without offset more stably, a CP signal arrangement signal having a specific pattern is recorded also in the area where the offset signal is recorded. When this signal is reproduced, the optical disk reproducing apparatus of the present invention changes the slice level when demodulating the RF signal into a digital signal substantially instantaneously and returns it to a normal value.

  As a result, the normal recorded area in which the center of the eye pattern is in the vicinity of the center of the amplitude following the signal of the specific pattern is reproduced, but the threshold for demodulating the RF signal of the reproduction apparatus into a digital signal is Since it has been returned to the normal value, it can be reproduced correctly.

  There is no particular problem with the signal of the specific pattern that changes the threshold value when demodulating the RF signal into a digital signal. As shown in FIG. 6C, for example, a threshold value is set to +1 so that the center of the eye pattern is on the mirror surface side (high reflectance side) of the amplitude in a region from a specific address An to another specific address An + 1. FIG. 6D shows whether the threshold offset amount is shifted to −1, for example, so that the center of the eye pattern is opposite to the mirror surface of the amplitude (the low reflectance side) as shown in FIG. 6 CP signal arrangement information 25 or a specific pattern signal. Alternatively, the direction of shifting may be specified for either one, and only shifting may be indicated by 1 and 0.

  Now, how to prevent the duplication of the optical disc of the present invention having the signal region in which the center of the eye pattern is largely shifted from the center of the amplitude as described above will be described.

  When the optical disc in the present embodiment is copied to an optical disc medium that can be written only once and can be played back by a normal playback device, the optical disc of the present embodiment is played back by the playback device and based on the signal demodulated into a digital signal The writing light is modulated and written on the optical disk medium.

  Even in an area where a signal in which the center of the eye pattern is greatly shifted from the center of the amplitude is recorded, the playback apparatus is provided with an auto level slicer that automatically corrects the slice level even if the duty ratio changes. Accordingly, since the threshold value when the auto level slicer demodulates the digital signal is automatically changed, it is reproduced as a normal correct signal. For this reason, a normal signal whose center of the eye pattern is almost in the center of the amplitude is also written on the replicated optical disc in the area where the signal of which the center of the eye pattern is greatly shifted from the center of the amplitude is recorded. Will end up.

  When the reproducing device reproduces the above-described duplicated optical disk, the auto level slicer outputs the RF signal in an area where a signal having an offset value, for example, Vs + ΔVs, is recorded with the center largely deviated from the center of the amplitude on a regular disk. Since the threshold value VsR when demodulating into a digital signal is not changed, a signal whose center of the eye pattern is almost in the center of amplitude is not discriminated from a regular disk because there is no offset. If the area where the signal of which the center of the eye pattern is greatly shifted from the center of the amplitude is recorded is present in the regular area and playback is not performed correctly, it has a means to stop playback. Stop.

  As described above, it is impossible to reproduce or operate the program of the duplicated optical disc, and it is possible to prevent the illegally duplicated optical disc from being used. In an optical disk, signals are generally recorded in a spiral shape from the innermost periphery to the outer periphery. In a compact disc (CD) or the like, a lead-in area is provided on the innermost periphery, and index information and the like of the optical disc are recorded.

  Also in the optical disc of the present embodiment, the area where the CP signal in which the center of the eye pattern is largely shifted from the center of the amplitude is recorded is the innermost circumference corresponding to the CD lead-in area 26 as shown in FIG. If it is provided in the unit, it is desirable that it is possible to quickly determine whether the optical disk has been duplicated at the start of reproduction.

  Hereinafter, the anti-duplication program will be described in more detail. The CD program reproduction is started at step 40a in FIG. 7 which is composed of three routines: a copy protection arrangement information reproduction routine 40x, an offset signal verification routine 40y, and a duplicate disk reproduction / program stop routine 40z.

  In step 40b, it is confirmed by the TOC flag or the like whether the disc is compatible with the CP signal. If Yes, the CP signal arrangement information 25 is obtained from the reproduction signal in step 40d as shown in FIG. When it is not step 40e, it stops, and only when it is, it proceeds to step 40f.

  In step 40f, the offset CP signal is checked in the offset CP signal arrangement region, and in step 40g, it is checked whether a CP signal, for example, an offset slice level, is present. If not, the process proceeds to step 40r and all check data must be completed. For example, the process returns to step 40f, and if all the check data is completed, the process proceeds to step 40p to determine that it is a duplicate disk.

  If Yes in step 40g, the process proceeds to step 40h, where the data of the offset CP signal arrangement information and the amplitude, period T0, address, and angular position of the physically detected offset CP signal are matched in the regular disk verification unit 33 in FIG. Make sure.

  If the verification is OK in step 40i, the process proceeds to step 40j, and the offset voltage ΔVs is forcibly added to the slice level based on the CP arrangement information 25, and it is checked in step 40k whether an error or an incorrect signal has occurred in the CP signal arrangement area. If an error of a certain level or more occurs in step 40m, it is determined that the disk is a duplicate disk in step 40p. If not, the process proceeds to step 40n. When all check data is completed, the program is operated in step 40w and completed. If not, the process returns to step 40f.

  If it is determined that the disk is a duplicate disk in step 40p, the display of “duplicate disk” is displayed on the display unit 41 in step 40q, the disk is ejected in step 40s, the program operation is stopped, and the data output is stopped in step 40t. In step 40u, all operations are stopped.

  Here, the reason why the error of step 40k occurs will be described. When the offset voltage changes significantly in a short time as in the case of the CP signals 24a and 24b in FIG. 6A, the response speed of the feedback control of the automatic correction slice circuit 31 does not follow. For this reason, an error occurs in a normal circuit.

  However, in the case of the present embodiment, it is known in advance that the offset voltage of the CP signal changes based on the offset CP signal arrangement information 25 and the CP preceding signals 26a, 26h, and 26b in FIG. Based on the preceding information, the offset correction signal generation unit 29 in FIG. 1 adds the offset correction signal ΔVs to the feedback loop 31 of the slice level Vs output unit 30 of the automatic correction slice circuit 31.

  Therefore, by adding the offset correction signal ΔVs at the changing point of the CP signal, the slice level Vs changes instantaneously to the value obtained by adding the offset ΔVs, and the CP signal can be normally reproduced without error. In the normally manufactured disc 9, since specific duty ratios such as 50:50, 30:70, and 70:30 are added to the pits of the disc, (a), (b), and ( As shown in c), an offset voltage is added to the slice voltage during reproduction, and three slice voltages of normal Vs, Vs + ΔVs, and Vs−ΔVs are generated.

  Therefore, reproduction can be performed without causing an error by adding a normal offset voltage to the slice voltage based on the offset CP signal arrangement information. In the regular disk verification unit 33, the error signal generation unit 38 receives the signal obtained by adding the predetermined offset voltage ΔVs from the offset correction signal generation unit 29 to the position of the predetermined address 36 of the CP signal arrangement information 37. Check for error signal. Alternatively, it is confirmed whether a normal signal code is reproduced from the digital demodulator 19. If it is a regular disc, playback is continued because the collation result is correct.

  If the collation result is not correct, a stop signal is issued from the playback / program stop unit 39 to stop the output of the playback signal or stop the program operation. Since the offset voltage is not duplicated in the illegally duplicated disk from the reproduction data of the regular disk, there is no predetermined offset voltage at the predetermined address position described in the CP signal arrangement information 25.

  Accordingly, the collating unit 33 in FIG. 1 can identify the disc as an illegal disk by collating the offset voltage. Further, in the slice level correction circuit 31 of FIG. 1, when the offset voltage of the normal offset voltage is large, the operation frequency that can be followed decreases to about the frequency f0. Assuming that this is f0, the slice level of the slice correction is offset by arranging the high offset voltage portion and the normal region as shown in FIG. 6 so that the offset voltage changes at a frequency of f0 or higher during reproduction. Fixed in the higher voltage direction.

  Therefore, the area of the normal offset value is sliced at a slice level higher than normal. In a regular disc, an error does not occur because the regular offset signal is recorded so that a regular signal is reproduced when sliced.

  However, only the data signal of the regular disk is taken out and the illegally duplicated disk cannot duplicate the offset voltage, so the CP signal area is sliced at the normal slice level without any offset voltage. For this reason, the normal signal is not reproduced and an error occurs, and the normal disk verification unit 33 in FIG. 1 determines that the disk is an illegal disk, and the operation stops.

  Also, as shown in FIG. 6, by providing the three types of CP preceding signals 26a, 26h, and 26b of +, 0, and −, the slice level of the data of the next frame synchronization signal can be predicted. By adding ΔVs to the feedback loop 31 of FIG. 1, the correct slice level can be set and changed instantaneously. For this reason, even if the slice level of the regular disk fluctuates at a frequency higher than the follow-up frequency of the slice level correction circuit, the slice is always sliced at the +, 0, and − slice levels defined for the regular disk. Will play without error.

  When a duplicate disc is created at the modulation signal level, the offset voltage is not copied. Therefore, the disc master is copied without changing the offset voltage in each offset CP signal recording area.

  On the other hand, the data of the CP preceding signal 26 is copied as it is to the illegally duplicated master. When the duplicate disk is reproduced and the positive CP preceding signal 26a is reproduced as shown in FIG. 6, the slicer slice level is increased in the positive direction as shown in FIG. 6C. Since the offset voltage is not recorded in the duplicate disc, the eye pattern has no offset as shown in FIG. 6B, and a normal signal cannot be output unless the slicer slice level is at the center.

  However, based on the offset CP signal arrangement information in the present embodiment, the slice level is forcibly set in the + direction. For this reason, an erroneous digital signal is output from the automatic correction slice circuit 31 of FIG. 1, an error signal is output from the error detection unit 38, and the regular disk verification unit 33 determines that it is a duplicate disk.

  An offset CP signal recording area in which a signal in which the center of the eye pattern is greatly shifted from the center of the amplitude is recorded can be easily produced because the pulse width, that is, the duty ratio is changed first by changing the recording equalization amount.

  As shown in the waveform (1) of FIG. 3, when the duty control signal is changed to a negative level when the period T0 is changed, the recording equalization amount is increased as shown in FIG.

  Then, the duty ratio becomes the waveform (2) of FIG. 3 and the irradiation time of the laser irradiated to the photoresist on the glass plate is shortened as shown in the recording waveform of (3) of FIG. (4) As in (5), a short signal pit having a small depth λ / 4 with a small duty is formed.

  When a short signal pit is reproduced as shown in waveform (5) of FIG. 3, since the amount of reflected light is less reduced, a signal in which the center of reflected light is shifted in the positive direction is obtained as shown in waveform (6) of FIG. As shown in the waveform (9) of FIG. 3, a signal is obtained in which the center of the eye pattern is shifted by the offset voltage ΔVs to the mirror surface side of the amplitude, that is, the side having the high reflectance.

  In this case, the well-known automatic correction slice circuit 33 of FIG. 1 operates to automatically correct the slice level to Vs + ΔVs obtained by adding the offset ΔVs to the slice level Vs. This state is shown by the waveform (7) in FIG. Then, as shown in the waveform (9) in FIG. 3, the slice is sliced at the signal level of 3T, so that a digital output with a correct 3T pulse width as shown in the waveform (8) of FIG. 3 is obtained.

  Thus, an offset voltage of + ΔVs is generated in the slicer. Conversely, when the recording equalization value, that is, the amount of “1001” is reduced, the duty is increased as shown in FIG. 4, the laser irradiation time is increased, and a long signal pit is formed. When a signal pit having a large duty ratio is reproduced, the offset voltage at the center of the eye pattern as shown in the waveform (d) of FIG. 6 is offset in the negative direction, that is, on the side opposite to the mirror surface of the amplitude, that is, on the low reflectance side. A signal that is shifted by a certain amount is obtained.

  A CP area in which an offset CP signal in which the center of the eye pattern is greatly shifted from the center of the amplitude by the offset voltage ΔVs can be easily produced by changing the power of the laser to be recorded.

  As shown in FIG. 4, when the recording laser power is reduced, the signal pit is reduced even with a normal recording power and an appropriate recording equalization amount. When a small signal pit is reproduced, the total amount of reflected light increases, and a signal in which the center of the eye pattern is shifted to the mirror surface side of the amplitude, that is, the side with high reflectivity, is obtained as shown in FIGS.

  When the recording power is increased, the signal pits are increased even with a normal recording power and an appropriate recording equalization amount as shown in FIG. When a large signal pit is reproduced, the amount of reflected light decreases, and a signal in which the center of the eye pattern is shifted by the offset voltage −ΔVs on the side opposite to the mirror surface of the amplitude (low reflectance) as shown in FIG. Is obtained.

  FIG. 4 schematically shows a change in the relationship between the recording power and the amplitude center of the eye pattern depending on the recording equalization amount. The horizontal axis represents the recording equalization amount. The larger the value is, the shorter the pulse width of the recording signal, that is, the duty becomes smaller. The vertical axis indicates the deviation amount of the center of the eye pattern from the amplitude center, that is, the offset amount ΔVs normalized by the amplitude and expressed as a percentage. When the duty control signal is reduced, the center of the eye pattern is shifted to the high reflectance side. Therefore, the offset voltage ΔVs increases in the positive direction. The recording power increases in the order of (a), (b), and (c). When the recording power of (a) is 1.0, (b) shows the case of 1.1, and (c) shows the case of 1.2.

  Waveforms 1 to 7 in FIG. 10 are shown when the recording power and the duty are changed. When the laser power is changed in this way, the pulse width needs to be corrected, and the yield is deteriorated. If it can be manufactured successfully, it is corrected by the slice level or the offset as shown in waveform 5, and a digital signal like waveform 6 is output. In this case, duplication is difficult due to poor yield.

  FIG. 5 shows an example of a master recording apparatus in which the recording equalization amount and recording power can be changed during recording. In FIG. 5, 1 is a recording laser, 2 is an optical modulator, 3 is a mirror, 4 is a lens actuator, 5 is a glass plate coated with a photoresist 5a, 6 is a spindle motor, 7 is a signal source, and 21 is a recording equalizer. , 22 is a control unit. The laser optical system for focus control and the beam expander of the recording laser optical system are omitted.

  A method for creating a master will be described with reference to the block diagram of FIG. 5 and the flowchart of FIG. In step 40a, normally, input data of a program in which a copy protection program such as computer software is previously incorporated is input. Separately, CP signal arrangement information 25 is input in step 40b.

  In step 40c, it is checked whether recording is performed on the inner peripheral portion. Only in the case of Yes, offset CP signal arrangement information 25 and recording data are mixed and recorded in the lead-in portion in step 40d.

  Next, in step 40e, recording of recording data is started. In step 40f, it is confirmed from the offset CP signal arrangement information 25 whether or not it is an offset signal recording area. If NO in step 40g, recording is performed with a normal duty in step 40i. If Yes, the CP signal generator 22a changes the duty ratio of the signal to the recording laser based on the offset CP signal arrangement information in Step 40h.

  In this way, the duty and output of the laser are controlled so that the offset voltage changes to a predetermined waveform.

  When all data is not finished in step 40j, the process returns to step 40f. When finished, it is checked in step 40k whether or not the offset CP signal arrangement signal 25 is recorded on the outer periphery, and when NO, the process is finished in step 40p. .

  In the case of Yes, the offset CP signal arrangement information pre-programmed in step 40m is compared with the offset CP signal amount, period, and arrangement deviation actually recorded by the mastering apparatus and corrected.

  Step 40n is shown in FIG. An offset CP signal arrangement information recording area is provided on the outer peripheral portion 5b of the master 5, and this correction data is recorded. In the mastering apparatus, since cutting is performed from the inner periphery toward the outer periphery, the offset creation result is used as data after all the data is recorded. The method of recording on the outer periphery has the effect of greatly improving the production yield of the master disk by recording the offset CP signal arrangement information 25 corrected with this data.

  When the recording equalization amount is changed after the offset CP signal arrangement signal having a specific pattern is generated from the signal generation unit 7, the control unit 22 instructs the pulse width control unit 21a of the recording equalizer 21 to record the recording equalization amount. Change the duty.

  When changing the duty for changing the recording power, the control unit 22 instructs the recording laser 1 to change the recording power. The recording laser 1 includes a laser and a power adjustment element, such as a noise eater or an AO modulator, and changes the power of the laser itself or changes the power with a power adjustment element. The recording equalizer 21 is configured to be able to switch the equalization amount by an external command.

  An area in which a signal in which the center of the eye pattern is greatly shifted from the center of the amplitude by the above method is recorded can be easily formed without any major modification to the master recording apparatus. The optical disc of the present invention can be manufactured in the same process as a conventional optical disc except for recording on the master, and can be manufactured in large quantities at a low cost.

  In the software containing the copy prevention program, the optical disc containing the copy prevention signal, and the optical disc reproducing apparatus with a copy prevention function according to the present embodiment, the reproduction of the copied disc or the operation of the software can be stopped. Duplication can be prevented.

  An example in which the offset CP signal arrangement information 25 is recorded in the optical ROM area is shown in FIG. 6. As shown in FIG. 8, this information is an RSA function or an elliptic function (ELLIPTIC CURVE FUNCTION) shown in FIG. Such a public key function is encrypted as a one-way function and recorded on a magnetic recording unit provided on the front surface or the back surface of the optical disk.

  Then, the CP signal arrangement information recorded in the magnetic recording unit cannot be altered unless an encryption key is obtained. This is because the encryption encoder function cannot be released from the encryption decoder function because the encryption is performed using a one-way function. For example, in the case of the usage as shown in FIG. 9, since only the encryption decoder is known, it is necessary to perform 2 512-bit power diagram calculation, which takes several million years. Thus, the CP signal arrangement information cannot be falsified.

  On the other hand, the offset CP signal is realized as shown in FIG. 10 by changing the duty ratio of the pulse width of the recording equalizer or changing the laser power, but the relationship between the laser output and the size of the pit hole is non-linear. Therefore, it is expected that the yield will decrease when a master having an offset voltage as programmed is produced.

  However, in this embodiment, as shown in FIG. 11, the CP signal arrangement information 25 is mixed with the logical ID and encrypted by the one-way function encryption encoder 42, and the magnetic recording circuit 44 and the magnetic head 45 are used for the magnetic recording unit 46 of the optical disk. To record. As described above, the CP signal arrangement information 25 cannot be falsified.

  The encrypted information is reproduced by the magnetic head 45a and the magnetic reproducing unit 48 of the recording / reproducing apparatus 47, decrypted by the encryption decoder 43, and the CP signal arrangement information 25 is decrypted. In this case, it is the same even if the CP signal arrangement information 25 is recorded in the optical recording unit and reproduced by the optical head 10. Then, in the disk collation program 49 described above, the CP arrangement information measured from the address detection unit 51, the offset voltage Vs0 detection unit 34, and the address or angle information in the offset voltage signal position detection unit 52 of the optical reproduction unit 50 is collated. To 49.

  The collation program 49 detects a duplicate disk based on the flowchart of the duplicate disk operation prevention program 49 described with reference to FIG. 7, and stops the operation of the program or stops outputting the reproduction signal.

  In this case, as shown in FIG. 13, disk check routines 40c, 40e, 40g, and 40i are incorporated into a startup routine 40b, a program installation routine 40d, a printing routine 40f, and a file storage routine 40h in the application software program. As a result, even if the pirated American analyzes the software and removes the copy prevention routines 40c, 40e, etc., there is an effect that the copy cannot be made unless all of the routines 154, for example, are removed.

  In the embodiment of FIG. 11, the method of encrypting and recording the CP signal arrangement information 25 such as the offset voltage of the master disk with a one-way function after creating the master disk in the magnetic recording unit 46 provided on the optical disk 9a is shown.

  This recording can be performed by recording a program and a CP signal on the first master 52 and recording the CP signal arrangement information 25 on the second master 53 at the outer periphery as in the optical disk 9b in the lower example of FIG.

  This method will be described in detail with reference to FIG. 12. In steps 1 and 2, a laser signal is given to the first master on the inner periphery, and in step 3, the second master 53, that is, the outer periphery is covered with a light shielding protective film 54. Then, the photoresist layer of the first photosensitive portion 55 is exposed to light. At this time, a pit pattern is formed by etching in the second photosensitive portion 56 step 4, and the offset signal is actually measured in step 5, the offset CP signal arrangement information 25 is obtained and encrypted, and the second photosensitive portion is encrypted in step 6. The light shielding protective film 54 is removed, and the encryption signal is recorded by the second laser exposure.

  Plating is performed in steps 7, 8, and 9, a metal master is made, a disk substrate is made by molding, a reflective film is formed, and a CD is made.

  By performing exposure for the second time, recording is performed by randomly giving an offset control signal on the first master, and the arrangement of the accepted offset CP signal is encrypted and recorded on the second master on the outer periphery or inner periphery. It is possible to record a copy protection signal with extremely bad production yield without worrying about the yield. For example, let's copy the signal of a thousandth fraction. This is because it is necessary to make a master disc 1,000 times, and a duplication business cannot be established economically.

  In addition, the rotation angle at which the offset CP signal is arranged is measured by the rotation angle detector 58 from the motor 57 and the lower six rotation pulses in FIG. 11, and the offset CP signal arrangement information 25a can be created as shown in FIG. As shown in FIGS. 16A to 16C, the angular position can be detected more accurately by dividing the rotation pulse time. As shown in FIGS. 16C and 16D, the arrangement of the address, the offset signal, and the cycle may be detected. In this case, since the disc is a regular disc, the measured offset CP signal arrangement information 25a is correct. That is, a signal having a cycle of T1 with a positive offset voltage is recorded at the position of the angular position Z3 at the address A4. The copy prevention program does not stop the program.

  However, in the illegally duplicated CD disc in FIG. 14B, the offset CP signal arrangement information 25c is different from the regular data. This is because the CD is recorded in the CLV, and FIG. 15 shows experimental data indicating that the actual CD address arrangement differs for each master. Even at the same address, the linear velocity and track pitch are slightly different depending on the master, so that errors are accumulated and a large difference occurs.

  Returning to FIG. 14, in the regular CD, the angular arrangement of the offset CP signal is Z3, Z2, Z1, and Z4. However, in FIG. 14B, it is Z3, Z2, Z4, Z3, and a remarkable difference appears. Accurate control of this angular position is not possible with currently available mastering devices.

  This pattern cannot be duplicated, and the offset CP signal arrangement information 25a cannot be falsified by the one-way function encryption. Therefore, there is a great effect that the replicator cannot copy this CD with the current apparatus. Further, the offset CP signal arrangement information 25 may be recorded on the optical disk by a bar code-like low reflection portion group.

  It is useful as a copyright protection technique for game software recorded on an optical disk and commercially available.

The block diagram which shows the structure of the optical disk reproducing | regenerating apparatus in embodiment of this invention The figure which shows an example of the eye pattern without the normal offset of an optical disk The figure which shows an example of the eye pattern at the time of giving the offset of the optical disk in embodiment of FIG. Variation diagram of asymmetry according to recording power and recording equalization amount in the same embodiment 1 is a block diagram showing the configuration of an example of a recording apparatus for an optical disc master in the same embodiment Explanatory drawing of the recording signal on the optical disk in the same embodiment Flow chart of duplicate disk operation prevention program in the same embodiment Explanatory drawing of four recording methods of CP signal arrangement information in the embodiment Disk verification flowchart using encryption in the embodiment Waveform diagram of offset voltage when changing pulse width and laser power in the same embodiment Block diagram of master production device and playback device in the same embodiment Process diagram of single-sheet master two-time division recording method in the same embodiment Flowchart of application software containing a copy prevention program in the embodiment Principle of anti-duplication in the same embodiment Coordinate arrangement diagram of address for each master of measured CD in the same embodiment Waveform diagram in the offset signal relocation detection method of the same embodiment Flowchart for recording offset CP signal on master disk in the same embodiment Block diagram showing the configuration of a conventional optical disk master recording device Block diagram showing the configuration of a conventional optical disk playback device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording laser 2 Optical modulator 3 Mirror 4 Lens actuator 5 Glass plate coated with photoresist 6 Spindle motor 7 Signal source 9 Optical disk 10 Optical pickup 11 Spindle motor 12 Analog waveform shaping unit 14 Digital signal processing unit 16 Focus servo unit 17 Tracking servo section 18 Rotating servo section 19 Digital demodulating section 20 Control section 21 Recording equalizer 22 Control section 23 Recording circuit 24 Offset signal 25 CP signal arrangement information 26 CP signal preceding signal 27 CP signal arrangement information reproducing section 28 Slicer 29 Offset correction signal generation Section 30 Slice level output section 31 Automatic correction slice circuit 32 Lead-in section 33 Verification section 34 Offset voltage Vs0 detection section 35 Slice level Vs output section 39 Playback / progress Stop unit 40 Step 41 Display unit 42 Cryptographic encoder 43 Cryptographic decoder 46 Magnetic recording unit 49 Regular disk verification program 50 Optical reproduction unit 51 Address detection unit 52 Master 53 Second master 54 Light-shielding protective film 55 First photosensitive part 56 Second photosensitive part Section 57 Motor 58 Offset CP signal arrangement information recording area

Claims (1)

An optical disc in which main information is recorded by placing marks and / or pits at predetermined positions on the circumference according to main information including copy-protected information,
By recording the pit by applying time-axis modulation based on the sub information to the main signal on the optical disc, the position of the front end of the outer edge of the pit is changed in the circumferential direction with respect to the predetermined position. the first region (24a, 24c) there is a second region (24b, 24d) and the change in the circumferential direction with respect to the predetermined position of the front end portion of the outer edge portion of the pit there is a change in the reverse direction and the Prepared,
In a playback apparatus for playing back an optical disc on which encrypted main arrangement information obtained by encrypting main arrangement information (CP signal arrangement information) related to the arrangement status of the first area and the second area is recorded on the disc.
The main arrangement information (25) is obtained from the main information obtained by reproducing the optical disc, and the change in the circumferential direction with respect to the predetermined position of the outer edge of the pit is detected by reproducing the optical disc. Sub-location information relating to the arrangement of the first region and the second region is obtained, the main arrangement information and the sub-location information are input to the collation unit (49), collation is performed, and the information is determined according to the collation result of the collation unit. A playback device that stops playback or output.

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