JP3984496B2 - Optical disk inspection apparatus, program, and method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection apparatus capable of suitably inspecting a portion subjected to the processing when there is a processing step for copyright protection in a manufacturing process of an optical disc such as a CD or a DVD.
[0002]
[Prior art]
In order to meet the needs of the market to distribute digital works at low cost and in large quantities, optical disc production sites have a system for increasing production day and night. The production of optical disks can be achieved by manufacturing processes such as substrate molding (1), reflection film deposition (2), protective film coating (3), substrate bonding (4), and label printing (5). In recent years, processing steps for copyright protection are often added to these manufacturing steps. This processing step is to write a special pit that cannot be created by a commercially available recording apparatus as a pit (certification pit) for authenticating a genuine disc on an optical disc on which a digital work is recorded. By providing the certification pit, the reproducing apparatus can distinguish between the original optical disc on which the genuine work is recorded and the optical disc on which the duplicate is recorded. As such a certification pit, a pit having a continuous length of 15T or more (T is a channel bit) may be used.
[0003]
[Problems to be solved by the invention]
By the way, in an optical disc production site, there is a case where a defect such that the playback device is confused with the certification pit may occur naturally. Natural defects that cause confusion induce misrecognition by the playback device. That is, in some cases, an operation of recognizing the disc as a legitimate optical disc but not recognizing it in some cases frequently occurs during reproduction. Such misrecognition can be a quality problem in the market. It must be avoided to ship optical discs to the market with natural defects that cause confusion.
[0004]
However, even if a process for inspecting the inclusion of natural defects is added, the time that can be spent for the inspection is limited. This is because, in an optical disc production site that requires mass production, unless the period required for such an inspection process is shortened as much as possible, the optical disc production plan will be greatly deviated.
An object of the present invention is to provide an inspection apparatus capable of performing high-speed inspection whether or not a natural defect that causes confusion with a certification pit exists in an optical disk processed for copyright protection. It is.
[0005]
[Means for Solving the Problems]
  Next to each otherFor each of multiple tracksProve that it is a genuine diskWhen there are n proof pits, natural defects that cause confusion with the proof pitsOr defective machining that forms incomplete proof pitsThe presence of s may be inspected using an inspection apparatus having the following configuration. This inspection apparatus is an apparatus that achieves the above-described object, and a reading unit that optically reads the plurality of tracks to obtain one reading signal corresponding to the plurality of tracks;Binarization means for binarizing the read signal to obtain a binarized signal, and the binarizationDetection means for detecting a signal section having a width corresponding to the continuous length of the certification pit from the signal, and any one of the detected signal sections and a signal section n ahead of the signal section IntervalShorter than the track circumferenceThen, there is a natural defect between any two proof pits.If it is determined that it exists and the interval is longer than the circumference of the track, there is a processing defect between any two certification pits.Determination means for determining,
Any one of the proof pits and the n proof pits exist on the same radius,
The plurality of proof pits existing on the same radius are formed by one irradiation of laser light,
  The continuous length of the certification pit is longer than that of the pits other than the certification pit, and is a continuous length that does not exceed the range in which error correction can be performed using an error correction code.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an inspection apparatus according to the present invention will be described below. The certification pit to be inspected by this inspection apparatus is a pit having a continuous length of 15T or more and having a continuous length that does not exceed the range in which error correction can be performed by the error correction code. A continuous length of 15T or more capable of error correction is called "continuous length X". The technical significance of using a continuous length X pit as a proof pit will be explained. A commercially available playback device and a commercially available recording device can be connected to read digital works recorded on an optical disc such as a CD-ROM or DVD-ROM, and recorded on a hard disk, CD-R, or DVD-R. As is well known, the user's action of recording on a type disc, so-called casual copy flooding, has become a social problem.
[0007]
However, the read signal obtained when optically reading the proof pit described above has a LOW section that lasts longer than 15T. Such a read signal cannot be reproduced by a commercially available reproducing apparatus and cannot be recorded on another optical disk by a commercially available recording apparatus. This is because a pit representing data on a DVD, which is a typical optical disc, is usually 3T to 14T in length, and when a read signal is read from a pit longer than this, commercially available playback devices and recording devices are out of norm. The read signal is subjected to error correction processing, converted into a read signal within the norm, and recorded on another optical disc. Therefore, a pit having a continuous length X cannot be recorded on a recordable disc by casual copying. FIG. 1 is a diagram showing a comparison between a pit having a continuous length X and a pit having a length of 3T to 14T. If the presence of a pit having a continuous length X is confirmed, it is possible to distinguish between a genuine disc manufactured by an authorized manufacturer and a recordable disc illegally manufactured by casual copying. Needless to say, the continuous length of the proof pit of 15T is merely an example, and this may be increased or decreased.
[0008]
Next, a manufacturing process of the optical disc to which the process of creating such certification pits is added will be described. FIG. 2 is a diagram showing a manufacturing process of the optical disc according to the present embodiment. This process is the same as an ordinary optical disc in that it is manufactured through a substrate forming process S1, a reflective film forming process S2, a protective film coating process S3, a bonding process S4, and a label printing process S5. The laser processing step S6 and the inspection step S7 performed after these steps are unique to the present embodiment.
[0009]
The laser processing step S6 is a step of obtaining n processed portions on a plurality of tracks of the optical disc by irradiating the optical disc with a YAG laser (Yttrium, aluminum, garnet).
In the inspection step S7, it is inspected whether or not the processed portion is obtained as intended by the manufacturer in the track processed by the YAG laser irradiation. If “normal” is obtained, the optical disc is determined to be a non-defective product, and if there is a processing defect on the processed track, or if there is a natural defect to be described later, it is determined as a defective product.
[0010]
The above is the outline of the optical disk manufacturing process. Subsequently, the processing location obtained in the laser processing step will be described in detail.
FIG. 3 is a diagram showing three machining locations E, F, and G obtained by the laser machining process. As shown in the figure, these processing points are provided on tracks R, R + 1, R + 2, R + 3,..., R + 5. In FIG. 3, the size of the processed portion is exaggerated and drawn to help understanding of the invention. The actual size of the processed portion is so small that it cannot be confirmed with the naked eye.
[0011]
FIG. 4 is an enlarged view showing the processing points E, F, and G obtained in the laser processing step. The processing location has a generally rectangular shape. This processing location exists on a plurality of adjacent tracks R, R + 1, R + 2, R + 3, R + 4, and R + 5. The reflection film is melted and peeled off at the intersections between these tracks and the processing points. The width X of the processed portion is a length of 15T or more, and is a continuous length “X” that can be corrected by the error correction code. Therefore, the above-mentioned continuous length X pits appear on these tracks. In the track corresponding to the end of the processed portion, the length of the intersecting portion is less than X. This is because the end by laser processing has a characteristic of being blunted (rounded). For example, when the five tracks shown in the figure are sequentially read, five LOW sections X having a width corresponding to the continuous length X appear in the read signal.
[0012]
In the present embodiment, as shown in the figure, it is a proof of a genuine disc that pits having a continuous length X are arranged along the radial direction on a plurality of adjacent tracks. Therefore, a disc having only one continuous length X pit or a disc having a plurality of continuous pits but not arranged in the radial direction is not treated as a genuine disc.
Requiring such strict requirements to recognize that it is a genuine disc is a manifestation of the desire to realize stronger copyright protection. In other words, if illegal copying technology more advanced than casual copying is used, the above-mentioned continuous-length X pits may be forged. However, it is impossible to arrange pits having a continuous length X along a radial direction on a plurality of adjacent tracks as shown in FIG. 4 unless a very expensive manufacturing facility is provided. In this embodiment, the copyright protection is further strengthened by stricter requirements for the genuine disk. The above is the detail about the process location obtained by a process process.
[0013]
Although the above-mentioned machining location is provided on the optical disc by the manufacturer, the continuous length X pits may be created randomly. In other words, in the optical disc manufacturing process, there is a case where a defect that is misleading with the proof pit occurs naturally. These defects occur due to the loss of the reflective film, the mixing of bubbles / dust, and the occurrence of dirt. Statistically, the shape of the natural defect is unspecified, and is not a clean rectangular shape such as the processed portion shown in FIG. FIG. 5 is an enlarged view of a naturally occurring defect. The shape of the natural defect shown in FIG. 5 is a distorted shape that is extremely long in the horizontal direction and short in the vertical direction. The natural defect in FIG. 5 intersects tracks R + 1, R + 2, and R + 3. The lengths of these intersecting portions are not uniform as in the machined portions, and the heads are long and short. The longest of the intersections is 15T and the short one is only 3T. Of the intersections between the natural defect and the track, the intersection having the continuous length X is referred to as a “defect pit”. Since the shape of the natural defect is distorted, even if a defect pit exists on a certain track, the defect pit does not necessarily exist on an adjacent track. If the missing pit is read, the LOW section X of 15T or more appears in the read signal as in the case of reading the machining location. In addition, the present embodiment does not assume the presence of a long missing pit exceeding the continuous length X, that is, a missing pit that is so long that error correction cannot be performed. This is because the occurrence of such defective pits is rare in a normal optical disc production site.
[0014]
Next, the processing defect portion will be described. FIG. 6 is an enlarged view showing a processing defect portion. As shown in this figure, the processing defect portion has a shape similar to the processing portion shown in FIG. 4, but there is no continuous length X pit that is an intersecting portion on an adjacent track. Many. It can be seen that the intersection with the track is missing on the way, and pits of continuous length X appear in a jump. This omission occurs due to defective film formation (i) of the reflective film, the end of the life of the processing laser light source (ii), and the fact that the processing laser itself is defective (iii).
[0015]
The above natural defects and defective processing points can be said to be by-products of the processing process. A missing pit of continuous length X is not a problem in terms of quality even if it exists in a track other than a track where a certain proof pit exists. The reason is as follows. As described above, the optical disk reproducing apparatus performs error correction on the read data when reading data from the optical disk. Even if there is a missing pit of continuous length X, the reproducing apparatus corrects the data corresponding to the missing pit and uses it, so this missing pit does not adversely affect the reproducing operation of the reproducing apparatus. The same applies to the missing pits that are less than the continuous length X. However, if a missing pit exists between a certain proof pit and a subsequent proof pit, the reproducing apparatus recognizes the missing pit as a proof pit. This is not desirable for quality control. The same can be said for processing defects. Then, the inspection for discovering these missing pits and processing defects will be described.
[0016]
In this inspection, tracks are optically read and the intersections are detected one by one. When n machining locations intersect with 5 tracks, each track has a total of n intersections, so there are 5 xn intersections in total for 5 tracks. . When reading from the optical disc, the crossing portion appears on the read signal as a LOW section X of 15T or more. If five tracks are read one track at a time from the inner circumference side to the outer circumference side, 5 × n LOW sections X of 15T or more exist in the read signal. Attention is paid to an arbitrary LOW section Xj among the 5 × n LOW sections X and a LOW section Xj + n that is n pieces ahead of the LOW section Xj. This LOW section Xj is assumed to correspond to the intersection between the machining location S and the track R. The LOW section Xj + n that is n pieces ahead of the LOW section Xj is considered to correspond to the intersecting portion obtained by intersecting the above-described machining location S and the adjacent track R + 1. Then, the interval between the LOW section Xj and the LOW section Xj + n is equal to the length of one track. As described above, in the read signal obtained by optical reading, the interval between the LOW section Xj and the n-th LOW section Xj + n is the track length. Keep in mind that this regularity is based on the fiction that there is no natural defect on the optical disc.
[0017]
When a natural defect is interspersed between the above-described proof pits (i), or when an intermediate crossing part is missing (ii), such as a defective machining point, this regularity is distorted. This is because in the case where there is a processing defect (ii), the LOW section corresponding to the crossing part in the middle is lost, and therefore the nth LOW section does not become the crossing part on the adjacent track. Also, if there are missing pits on the track where the machining location is located (i), one or more LOW intervals X occur, so the LOW interval X corresponding to the intersection of the machining location S and the track R + 1 is It is n + 1 ahead instead of n ahead. That is, in these cases (i) and (ii), the regularity that the interval between the LOW section Xj and the n-th LOW section Xj + n becomes the track length is out of order.
[0018]
In other words, when reading from multiple tracks, if the regularity of whether the interval between the LOW section Xj and the n-th LOW section Xj + n is the track length is monitored, the presence of processing defects The presence of missing pits can be discovered.
Based on the above-described theory, the inspection apparatus according to the present embodiment is configured to determine whether or not there are missing pits or processing defects. FIG. 7 is a diagram showing an internal configuration of the inspection apparatus according to the present embodiment. As shown in FIG. 7, the inspection apparatus includes a laser processing unit 1, a track scanning unit 2, a binarization unit 3, a sector address detection unit 4, a certification pit detection unit 5, a certification pit information creation unit 6, and a certification pit information storage unit. 7, a sector number calculation unit 8, a sector number comparison unit 9, and a certification pit information writing unit 10. Hereinafter, components of the inspection apparatus will be described with reference to FIG. FIG. 8 is a timing chart showing how signals are input / output inside the inspection apparatus when one of a plurality of intersections is read.
[0019]
The laser processing unit 1 performs n times of laser processing of irradiating the YAG laser to the processing radius position P of the optical disk.
The track scanning unit 2 includes an optical head and an actuator, and optically reads a part of a plurality of tracks processed by the laser processing unit 1. The first row in FIG. 8 shows the sector on the track to which the intersecting portion belongs, and the second row shows the pit string formed in that sector. When the track scanning unit 2 reads the second pit row, a read signal having a waveform corresponding to the unevenness in the pit row is obtained as shown in the third row.
[0020]
The binarizing unit 3 binarizes the read signal obtained by reading by the track scanning unit 2 to obtain a binarized signal. If the threshold for binarization is sh1 shown in the third level of FIG. 8, the binarized signal obtained by the binarization unit 3 is shown in the fourth level of FIG.
The sector address detector 4 detects a sector address from the binarized signal output from the binarizer 3. When the sector address is detected for the read signal shown in the third row in FIG. 8, the output from the sector address detector 4 is as shown in the seventh row. That is, the sector address “A” is continuously output from the sector address detection unit 4 during the period of reading the pit row belonging to the sector A on the optical disc, and the sector address is read during the period of reading the pit row belonging to the sector A + 1. The detection unit 4 continuously outputs the sector address “A + 1”.
[0021]
The proof pit detector 5 monitors the width of the LOW section constituting the binarized signal output from the binarizer 3, and if the width exceeds a predetermined upper limit length, the LOW section X is detected. As a detection signal. Then, it waits for the LOW section X to switch to the HIGH section, and outputs a signal indicating the width of the LOW section X when switching occurs. In the timing chart of FIG. 8, the LOW section X continues for 15T or more at time tm1. Therefore, the proof pit detector 5 outputs a detection signal as shown in the fifth stage at this timing tm1. Also, since the LOW section X is switched to the HIGH section at time tm2, the certification pit detector 5 outputs a signal indicating the width “30” of the LOW section X as shown in the sixth stage at time tm2. is doing.
[0022]
The certification pit information creation unit 6 creates certification pit information for specifying the location of these pits and writes them in the certification pit information storage unit 7 every time an intersection is detected regardless of the certification pit and the missing pit. The certification pit information is created at the timing when the detection signal is output from the certification pit detection unit 5, and the produced certification pit information is “serial” given to this intersection by the certification pit information creation unit 6. The “number”, the “sector address” detected by the sector address detection unit 4, the “width” of the LOW section X detected by the certification pit detection unit 5, and the “determination column”. In the timing chart of FIG. 8, the certification pit information is generated at the time tm1 when the LOW period continues for 15T or more, and the sector detected by the certification pit detection unit 5 as indicated by the arrows yj1,2,3 is generated in this certification pit information. The address “A”, the serial number “1”, and the width “30” of the LOW section detected by the certification pit detector 5 are set. In the inspection apparatus configured as described above, the certification pit information is created every time a LOW section X of 15T or more is detected.
[0023]
The certification pit information storage unit 7 stores a plurality of certification pit information created by the certification pit information creation unit 6. FIG. 9 is a diagram showing a plurality of certification pit information generated by the certification pit information creation unit 6. In this figure, serial numbers “1”, “2”, and “3” identify the respective intersections, and indicate that each intersection is detected first, second, and third. Addresses “A”, “A + 10”, “A + 24”, “A + 36”, and “A + 46” indicate to which sector each intersection belongs. The widths “30”, “40”, “50”, “33”, and “38” indicate the length of each intersection. The certification pit information for all the intersections detected at the time of reading the entire track circumference is accumulated in the certification pit information storage unit 7.
[0024]
The sector number calculation unit 8 calculates how many machining locations are provided in the track to which the intersection corresponding to the certification pit information belongs (this number is n). The number T of sectors constituting the track varies depending on where the track is located on the radius. For example, in a track located at a radial position of 30 mm, the number of sectors per track is a non-integer value “36 ± 1 sector”. Therefore, the sector number calculation unit 8 obtains the number of sectors T constituting the track to which the certification pit belongs from the radius position on the processed optical disk.
[0025]
The sector number comparison unit 9 extracts sector addresses from the certification pit information j corresponding to the intersection j and the certification pit information j + n corresponding to the intersection j + n, and calculates the difference between these sector addresses. If the calculated difference is the number of sectors T in the track and corresponds to the number of sectors constituting one track, the intersection j corresponding to the certification pit information j and the intersection j + corresponding to the certification pit information j + n It is considered that there is no defect pit between n and no processing defect. Then, it is determined that the intersection j corresponding to the certification pit information j and the certification pit information j + n is “normal”. On the other hand, if the calculated difference is not the number of sectors in the track, is there a missing pit between the intersection j corresponding to the certification pit information j and the intersection j + n corresponding to the certification pit information j + n? Or, it is considered that there is a processing defect. Then, it is determined that the intersection j to j + n is “abnormal”. For certification pit information considered “normal”, “normal” is entered in the judgment column, and for certification pit information considered “abnormal”, “abnormal” is entered in the judgment column.
[0026]
The certification pit information writing unit 10 can additionally write a plurality of certification pit information stored in the certification pit information storage unit 7 whose determination column is set to “normal” in advance on the optical disc. Write to an area or rewritable area. Thereby, the intersection corresponding to the certification pit information in which the determination column is set to “normal” is specified as the certification pit.
[0027]
The sector number comparison unit 9 plays a central role in the above inspection apparatus. The entity of the sector number comparison unit 9 is a general-purpose computer and a program executable by the computer. FIG. 10 is a flowchart showing the control structure of this program. In this flowchart, after the track scanning unit 2 performs track scanning and the certification pit information creation unit 6 creates certification pit information (step S11), it executes a loop process including steps S12 to S23. It has a control structure. This loop processing uses the variable “j” as a control variable. In this loop process, the process of setting the determination column for the j-th proof pit information in either step S20 or step S22 is repeated for all the proof pit information. Step S20 is to set the judgment column of the certification pit information j and the certification pit information j + n to “normal”, and step S22 sets the judgment column from the certification pit information j to the certification pit information j + n to “abnormal”. Is set to "." Switching between step S20 and step S22 is left to step S13, step S18, and step S19. Step S13 extracts the sector address for the jth certification pit from the certification pit information j (this sector address is referred to as “sector address j + n”), and step S18 is the sector address for the j + nth certification pit. Is extracted from the certification pit information j + n (this sector address is referred to as “sector address j + n”). Step S19 is a determination step for determining whether or not “sector address j + n−sector address j” is the number of sectors T. If so, step S20 is executed, and if not, step S22 is executed. The
[0028]
This loop processing end condition is defined in step S16, and it is determined that there is no intersection j + n corresponding to “j + n”. The numerical value n is calculated by specifying the track R to which the intersecting portion j belongs (step S14), and detecting the number T of sectors constituting the track R and the number n of machining points provided for the track R. (Step S15).
[0029]
The control variable j is initialized in step S12, and the control variable j is incremented in steps S21 and S23. There are two increments in step S21: when the determination field is set in step S20 (i), and when the determination field is determined to be already set in step S17 (ii).
The increment in step S23 is executed when the determination field is set in step S22. The reason why the increment of the control variable is set to “1 + n” instead of “1” in step S23 is to skip n items to be set in the determination column. When the sector number comparison unit 9 performs the process according to such a control structure, the verification pit determination column is set.
[0030]
Three typical operation examples are shown below. In these operation examples, it is assumed that the number n of machining points is “3”.
The first case is a case where two tracks R and R + 1 intersect at three machining locations as shown in FIG. FIG. 11B shows a detection signal read from such a track R, R + 1, and FIG. 11C shows four pieces of proof pit information 1, 2, 1 created based on this detection signal. FIG.
[0031]
When the four proof pit information shown in this figure is stored in the proof pit information storage unit 7, it corresponds to the sector identification information A of the proof pit information 1 corresponding to the first intersection and the three intersections ahead The difference S between the identification pit information 4 (= 1 + 3) and the sector identification information A + 36 is calculated as S = 36. Since the difference s is in the range of 36 ± 1 sectors per track, the certification pit information 1 and 4 are judged to be “normal”, and the judgment column for the certification pit information 1 and 4 is set to “normal” The FIG. 11 (d) shows the result.
[0032]
In the following case, as shown in FIG. 12A, one natural defect intersects with two tracks R and R + 1 together with three machining points. FIG. 12B shows a detection signal read from such a track, and FIG. 12C shows four verification pit information 1, 2, 3, and 4 created based on this detection signal. ing.
[0033]
When the four certification pit information shown in this figure is accumulated in the certification pit information storage unit 7, the sector identification information A of the certification pit information 1 corresponding to the first intersection and the certification pit information 1 three after The difference between the detected certification pit information 4 and the sector identification information A + 24 is calculated, and the difference “24” is compared with the number of sectors per track of 36 ± 1. Since the difference is smaller, the determination column from the certification pit information 1 to the certification pit information 4 is set to “abnormal”. FIG. 12D shows the result.
[0034]
Finally, the case where one of the three processing points is defective is shown. FIG. 13A shows a typical example of such a case. That is, FIG. 13B shows detection signals that are not detected at the intersections between the sector address A + 10 and the sector address A + 46. Yes. That is, in the detection signal of FIG. 13B, since the LOW section X of the sector address A + 10 and the LOW section X of the sector address A + 46 are missing, certification pit information is created for these intersections. Not. The certification pit information 1, 2, 3, 4 stored in the certification pit information storage unit 7 in FIG. 13C is for sector addresses A, A + 24, A + 36, A + 50.
[0035]
If the inspection apparatus performs processing for this specific example, the sector identification information A of the certification pit information j and the sector identification information A + 50 of the certification pit information j detected after n = 3 pieces of the certification pit information j And the difference 50 becomes larger than 36 ± 1 sectors per track. As a result, it is determined that the intersection portion that should be originally detected is not included between the intersection portion 1 and the intersection portion 4, and the processing is not “normal”. For this reason, as shown in FIG. 13 (d), “abnormal” is written in the determination columns of the certification pit information 1 to 4.
[0036]
As described above, according to the present embodiment, since the presence or absence of a missing pit is determined by measuring the interval from a certain LOW interval to the n-th LOW interval in the read signal, the time required for the inspection of the processing location is Very little. Even if the number of manufacturing steps is increased due to the inspection of the processed portion, there is no error in the optical disc production plan, and it is possible to produce a remarkable effect that a copyright-protected optical disc can be produced in large quantities and with high quality.
[0037]
(Second Embodiment)
In the first embodiment, it was inspected that the interval to the n-th LOW section is the length of one track. In the second embodiment, the number of LOW sections with a width X appearing in a read signal read from a plurality of tracks intersecting with a processing location is counted, and a non-defective / defective product is determined based on this number.
[0038]
FIG. 14 shows the internal configuration of the inspection apparatus according to the second embodiment. In this figure, the sector number comparison unit 9 shown in FIG. 7 is replaced with a counter 11 and a number comparison unit 12.
The counter 11 obtains the number M of certification pit information per track from the number of sectors of one track obtained by the sector number calculation unit 8 and the certification pit information stored in the certification pit information storage unit 7. When the certification pit information as shown in FIG. 11C is detected, the number of certification pit information per track M = 3 since there are three certification pit information in the sector number 36 ± 1 per track. It becomes.
[0039]
The number comparison unit 12 compares the number M of certified pit information obtained by the counter 11 with the number n of certified pits added per track.
When M = n, all of the n processed proof pits have been detected, so the number comparison unit 12 writes “normal” in the determination column of the corresponding proof pit information in the proof pit information storage unit 7.
[0040]
When M> n, it is considered that there are (M−n) missing pits among the M detected as the certification pit information. At this time, the number comparison unit 12 writes “abnormal” in the determination information of the corresponding certification pit information in the certification pit information storage unit 7.
In the case of M <n, (n−M) of the n processed proof pits were not detected. In this case, either “normal” processing has not been performed or “normal” has not been detected, and the number comparison unit 12 determines the determination information of the corresponding certification pit information in the certification pit information storage unit 7. Write "abnormal" in
[0041]
After the determination of all the certification pit information in the certification pit information storage unit 7 is completed, the certification pit information whose judgment information is “normal” is written in the additionally recordable area or the rewritable area of the optical disc 100.
As described above, according to the present embodiment, it is possible to determine whether or not there is a missing pit by comparing the number of certified pits processed with the number of detected certified pit information per track. Furthermore, it is also possible to determine when the proof pit cannot be detected correctly due to processing failure.
[0042]
The inspection in the second embodiment and the inspection in the first embodiment are compared to verify which is better. Consider a case where one of the proof pits on the entire track is missing due to a laser processing defect and a missing pit exists instead. Such a case should be determined to be abnormal in nature because there are missing defective machining points and missing pits. However, in the procedure of the second embodiment, since the number of LOW sections of the width X in the read signal from the track circumference is used for the inspection, the above case may be determined as “normal”. On the other hand, in the procedure of the first embodiment, since the interval between pits having a continuous length X is used for inspection, the above-described case can be determined as “abnormal”. A case that may be overlooked in the second embodiment can be determined as “abnormal” in the first embodiment. Therefore, if a stricter inspection is desired, the procedure of the first embodiment should be performed. .
[0043]
Although it has been described based on the above embodiment, it is merely presented as an example of a system that can be expected to have the best effect in the present situation. The present invention can be modified and implemented without departing from the gist thereof. As typical modified embodiments, there are the following (A), (B), (C),...
(A) It is desirable that the track to be read in the first embodiment is kept within a range where the head can be driven by the actuator. This is because if the reading range is expanded to a range where head seeking is necessary, the time required for inspection per optical disc becomes longer.
[0044]
(B) In the first embodiment, when the interval of the LOW section does not become the length of the track due to reasons such as a missing pit on the track, the reading position by the track scanning unit 2 is set to a plurality of tracks ahead. It is desirable to retry the inspection after slipping. As shown in FIG. 12 (a), the size of the naturally occurring defect is often very small compared to the machining location. There are not a few cases in which the sector number comparison unit 9 determines “normal” by changing the track to be read to a plurality of tracks ahead. Since such a retry improves the yield rate, the yield can be increased.
[0045]
(C) In the first embodiment, the inspection apparatus performs the inspection before the optical disk is shipped as a product in the manufacturing process of the optical disk. However, the optical disc after shipment and owned by the user may be inspected. The case of the “distribution terminal” corresponds to the case where the inspection apparatus inspects the optical disk that is owned by the user. A “distribution terminal” is installed in a convenience store or the like, and receives a distribution of digital works and performs a service of writing on an optical disk owned by a user. From the viewpoint of preventing casual copying, it is necessary to limit the use of the copyrighted work written in this way to the optical disc. Therefore, the distribution terminal performs processing as described in the first embodiment on the optical disk. Then, the inspection shown in the first embodiment is performed on the processed portion thus obtained. For such inspection, an inspection device is built in the distribution terminal.
[0046]
(D) In this embodiment, the sector number calculation unit 8 measures the length of the track where the machining location exists. However, if the machining location is a fixed position, the sector number calculation unit 8 may be omitted. Good.
(E) The characteristic of the inspection apparatus described in the first embodiment is the processing procedure of the sector number comparison unit 9. In the inspection apparatus, this characteristic part is a program built in these apparatuses (see the flowchart of FIG. 10). ) Is implemented. Therefore, the program that is a characteristic part of the inspection apparatus may be executed independently of these apparatuses. The program may be recorded on a computer-readable recording medium, and the recording medium may be transferred or lent. The program may be distributed on the network.
[0047]
In addition, since it is an essential feature that the other characteristic parts are also implemented as an improvement of the program, the program as the characteristic part may be executed independently from these devices.
(F) The occurrence of a processing defect location as shown in FIG. 6 occurs due to the fact that the processing laser emission source has expired (ii) and the processing laser itself has a defect (iii). When it is detected that the number of sectors indicating the interval of the LOW section exceeds the track length, a warning may be given that there is a possibility that the abnormalities (i) and (ii) may exist. This is because the processing laser can be replaced quickly.
[0048]
  As described above, the inspection apparatus according to the present invention is
  In an optical disc that has been processed to provide n proof pits that prove authenticity on each of a plurality of adjacent tracks, any two proof pits have a natural defect or a defective processing of the proof pit. An inspection device for inspecting whether or not there exists (n is an integer of 1 or more),Reading means for optically reading the plurality of tracks to obtain one reading signal corresponding to the plurality of tracks;Binarization means for binarizing the read signal to obtain a binarized signal;  BinarizationDetecting means for detecting a signal section having a width corresponding to the continuous length from the signal, and in the detected signal section, an interval between any one of the signal sections and a signal section that is n times ahead from the signal section is; ,If it is shorter than the track circumference, It is determined that a natural defect is interspersed between any two proof pits.If the interval is longer than the track circumference, it is determined that there is a machining defect between any two certification pits.Determination means forAny one of the above-mentioned proof pits and the n proof pits exist on the same radius,
The multiple proof pits existing on the same half are formed by a single irradiation of laser light, and the continuation length of the proof pit is longer than the pits other than the proof pit, It is characterized by a continuous length that does not exceed the range in which error correction is possible with a correction code.
[0049]
When only the proof pits obtained by processing exist on a plurality of tracks, the interval between the signal section and the n-th signal section is the reference value. On the other hand, in addition to the certification pit, when there is a natural defect on the track that is confused with the certification pit, a signal section corresponding to the natural defect is added to the read signals from a plurality of tracks. For this reason, when a natural defect is present on the optical disc, the interval from any signal interval to the n-th signal interval is not a reference value. Since the presence or absence of the natural defect is determined by measuring the interval of the signal section, the time required for the inspection by the inspection apparatus becomes very short. Even if the number of manufacturing steps is increased due to the inspection by the inspection apparatus, there is no error in the optical disk production plan, and it is possible to produce a remarkable effect that a copyright-protected optical disk can be produced in large quantities with high quality.
[Brief description of the drawings]
FIG. 1 is a diagram showing a comparison between a pit having a continuous length X and a pit having a length of 3T to 14T.
FIG. 2 is a manufacturing process diagram of an optical disc according to the present embodiment.
FIG. 3 is a diagram showing three machining locations E, F, and G obtained by a laser machining process.
FIG. 4 is an enlarged view showing a processing portion obtained in a laser processing step.
FIG. 5 is an enlarged view showing an example of a naturally occurring defect.
FIG. 6 is an enlarged view showing a processing defect.
FIG. 7 is a diagram showing an internal configuration of the inspection apparatus according to the present embodiment.
FIG. 8 is a timing chart showing how signals are input and output in the inspection apparatus when one of the certification pits is read.
FIG. 9 is a diagram showing a plurality of certification pit information created by a certification pit information creation unit 6;
FIG. 10 is a flowchart showing a control structure of a program constituting the sector number comparison unit 9;
FIG. 11A is a diagram showing a case where three machining points intersect with tracks R and R + 1.
(B) It is a figure which shows the detection signal output at the time of reading from track | truck R, R + 1 shown to (a).
(C) It is a figure which shows four certification pit information 1,2,3,4 produced based on the detection signal of (b).
(D) It is a figure which shows four certification pit information 1,2,3,4 with which the determination column was set.
FIG. 12A is a diagram showing a case where three machining locations and a natural defect intersect with tracks R and R + 1.
(B) It is a figure which shows the detection signal output at the time of reading from track | truck R, R + 1 shown to (a).
(C) It is a figure which shows four certification pit information 1,2,3,4 produced based on the detection signal of (b).
(D) It is a figure which shows four certification pit information 1,2,3,4 with which the determination column was set.
FIG. 13 (a) is a diagram showing a case where a processing failure location is such that tracks R and R + 1 intersect.
(B) It is a figure which shows the detection signal output at the time of reading from track | truck R, R + 1 shown to (a).
(C) It is a figure which shows four certification pit information 1,2,3,4 produced based on the detection signal of (b).
(D) It is a figure which shows four certification pit information 1,2,3,4 with which the determination column was set.
FIG. 14 is a diagram showing an internal configuration of an inspection apparatus according to a second embodiment.
[Explanation of symbols]
1 Laser processing part
2-track scanning section
3 Binarization part
4 Sector address detector
5 Certification pit detector
6 Certification pit information creation department
7 Certification pit information storage
8 Sector number calculator
9 Sector number comparison part
10 Certification pit information writing part
11 counter
12 Number comparison part

Claims (4)

In an optical disc that has been processed to provide n proof pits that prove authenticity on each of a plurality of adjacent tracks, any two proof pits have a natural defect or a defective processing of the proof pit. An inspection device for inspecting whether or not there exists (n is an integer of 1 or more),
Reading means for optically reading the plurality of tracks to obtain one reading signal corresponding to the plurality of tracks;
Binarization means for binarizing the read signal to obtain a binarized signal;
Detecting means for detecting a signal section having a width corresponding to the continuous length of the certification pit from the binarized signal;
In the detected signal section, if the interval between any one of the signal sections and the signal section n ahead from the signal section is shorter than the track circumference , there is a natural defect between any two verification pits. And determining means for determining that there is a processing defect between any two verification pits if the interval is longer than the track circumference ,
Any one of the proof pits and the n proof pits exist on the same radius,
More proof pits present on the same radius state, and are not formed by one time irradiation of a laser beam,
The continuous length of the certification pit is a continuous length longer than the pits other than the certification pit, and is a continuous length that does not exceed the range in which error correction can be performed by an error correction code.
Inspection apparatus characterized by that. The interval of the signal interval is
It is represented by the difference between the address of the sector corresponding to any signal interval and the address of the sector corresponding to the nth signal interval,
Difference of the same address, determining means inspection apparatus according to claim 1, characterized in that it is compared with the number of sectors existing on the track around the. In an optical disc that has been processed to provide n proof pits that prove authenticity on each of a plurality of adjacent tracks, any two proof pits have a natural defect or a defective processing of the proof pit. In the meantime, a program for causing a computer to check whether it exists or not (n is an integer of 1 or more),
A step of optically reading the plurality of tracks to obtain one read signal corresponding to the plurality of tracks;
A binarization step of binarizing the read signal to obtain a binarized signal;
A detection step of detecting a signal section having a width corresponding to the continuous length of the certification pit from the binarized signal;
In the detected signal section, if the interval between any one of the signal sections and the signal section n ahead from the signal section is shorter than the track circumference , there is a natural defect between any two verification pits. judgment, if the interval is longer than the track round length, between any two certification pits, possess and determining steps and processing failure is present,
Any one of the proof pits and the n proof pits exist on the same radius,
The plurality of proof pits present on the same half is formed by a single irradiation of a laser beam,
The proof pit has a continuous length that is longer than a pit other than the proof pit, and is a continuous length that does not exceed a range in which error correction can be performed using an error correction code . In an optical disc that has been processed to provide n proof pits that prove authenticity on each of a plurality of adjacent tracks, any two proof pits have a natural defect or a proof pit processing failure. In the meantime, it is a method of checking whether or not it exists (n is an integer of 1 or more),
A step of optically reading the plurality of tracks to obtain one read signal corresponding to the plurality of tracks;
A binarization step of binarizing the read signal to obtain a binarized signal;
A detection step of detecting a signal section having a width corresponding to the continuous length of the certification pit from the binarized signal;
In the detected signal section, if the interval between any one of the signal sections and the signal section n ahead from the signal section is shorter than the track circumference, there is a natural defect between any two verification pits. Determining, if the interval is longer than the circumference of the track, a determining step for determining that there is a processing defect between any two certification pits;
Have
Any one of the proof pits and the n proof pits exist on the same radius,
The plurality of proof pits present on the same half is formed by a single irradiation of a laser beam,
2. The inspection method according to claim 1, wherein the proof pit has a continuous length that is longer than a pit other than the proof pit and does not exceed a range in which error correction can be performed with an error correction code.

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