JP3656782B2 - Optical disk evaluation apparatus and optical disk evaluation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk evaluation apparatus and an optical disk evaluation method, and is applied to evaluation of a compact disk, for example, to measure the timing at which the signal level of a reproduction signal crosses a predetermined reference level, and to measure time for each recording pattern By collecting the results, the optical disk can be evaluated easily and in detail.
[0002]
[Prior art]
Conventionally, in a compact disk, a disk-shaped substrate is formed by transferring minute irregularities formed on a stamper by a method such as injection molding, 2P method, etc., and then a light reflecting film or the like is formed on the disk-shaped substrate. To be created.
[0003]
That is, in the manufacturing process of the compact disc, the signal level changes in a period of 3T to 11T with respect to a predetermined basic period T by performing EFM (Eight-to-Fourteen Modulation) modulation after data to be recorded is processed. A modulation signal to be generated is generated, and the disc master is exposed by this modulation signal. Subsequently, in the manufacturing process, after this disc master is developed, electroforming is performed to create a metal mask. Further, in the manufacturing process, a plurality of mother disks are created from the metal mask, and a plurality of stampers are created from the mother disks.
[0004]
When a compact disc is manufactured by an injection molding technique, a compact disc manufacturing process is performed by setting a mold including the stamper in an injection molding machine and injection molding a transparent resin such as polycarbonate using the mold. As a result, the manufacturing process creates a disc-shaped substrate formed by transferring minute irregularities formed on the stamper, and then forms a light reflecting film, a protective film, etc. on the disc-shaped substrate to produce a compact disc.
[0005]
On the other hand, when manufacturing a compact disc by the 2P method, the compact disc manufacturing process involves filling the space of a certain thickness formed on the stamper with an ultraviolet curable resin and then curing the ultraviolet curable resin. Then, it is removed from the stamper and a disk-shaped substrate is created. Thereafter, in the manufacturing process, this disk-shaped substrate is processed in the same manner as in the case of injection molding to produce a compact disk.
[0006]
As a result, the compact disc has a delicate pit shape due to the pressure, temperature, and other conditions during injection molding, and in the case of the 2P method, due to the pressure when filling the ultraviolet curable resin. Change. Similarly, depending on the manufacturing conditions such as the intensity and temperature of the laser beam at the time of exposure, the shape of the pit in the metal mask, and also in the mother disk and stamper made from this metal mask, the shape of the pit depends on various conditions. Change.
[0007]
Such a change in pit shape is observed as a change in jitter and asymmetry of the playback signal during playback. When the jitter and asymmetry of the compact disk deteriorate significantly, it becomes difficult to correctly reproduce the recorded data. .
[0008]
For this reason, in the conventional manufacturing process, various conditions in the manufacturing process are converged by reproducing a compact disc and measuring jitter and asymmetry.
[0009]
[Problems to be solved by the invention]
However, in such jitter and asymmetry measurements, the pit shape of the compact disc is comprehensively determined. That is, such measurement is performed by averaging the degree of deformation of pits having a period of 3T to 11T formed on a compact disc.
[0010]
If such a pit shape can be evaluated easily and in detail, it is considered that various conditions in this type of manufacturing process can be quickly and reliably converged.
[0011]
As one method for solving this problem, a method of magnifying and observing pits with an electron microscope or the like can be considered, but there is a problem that it takes time for evaluation.
[0012]
The present invention has been made in consideration of the above points, and an object of the present invention is to propose an optical disk evaluation apparatus and an optical disk evaluation method capable of evaluating an optical disk simply and in detail.
[0013]
[Means for Solving the Problems]
In order to solve such a problem, in the present invention, the timing of the clock for the pits formed on the optical disc is measured by measuring the timing at which the signal level of the reproduction signal crosses a predetermined reference level with reference to the clock. Edge misregistration is detected to obtain a misregistration detection result, and the edge misregistration detection result is classified and tabulated for each pit length .
[0014]
By measuring the timing at which the signal level of the reproduction signal crosses a predetermined reference level with respect to the clock, the edge position deviation of the pit formed on the optical disc is detected with reference to the clock timing. If the position shift detection result is obtained, the edge timing in the binarized signal obtained by binarizing the reproduction signal can be measured. Accordingly , if the edge displacement detection results are classified and tabulated for each pit length, the edge timing can be tabulated according to the pit length formed by the recording pattern.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
[0016]
(1) First Embodiment FIG. 1 is a block diagram showing an optical disk evaluation apparatus according to an embodiment of the present invention. This optical disk evaluation apparatus 1 uses an edge for pits formed on a compact disk 3. The pit shape of the compact disc 3 is evaluated by measuring the positional deviation.
[0017]
That is, in this optical disk evaluation apparatus 1, the compact disk player (CD player) 2 is controlled by the computer 4 to switch its operation and reproduce the compact disk 3. At this time, the compact disc player (CD player) 2 irradiates the compact disc 3 with a laser beam, and outputs a reproduction signal RF whose signal level changes according to the amount of return light obtained as a result.
[0018]
The digital oscilloscope 5 is controlled by the computer 4 to switch its operation, performs an analog-digital conversion process on the reproduction signal RF at a sampling frequency 20 times the channel clock, and outputs the resulting digital signal to the computer 4.
[0019]
The computer 4 controls the operation of the digital oscilloscope 5 and processes the digital signal output from the digital oscilloscope 5, thereby outputting the evaluation result of the compact disk 3 to the printer 6.
[0020]
FIG. 2 is a flowchart showing a processing procedure in the computer 4. In this processing procedure, the computer 4 proceeds from step SP1 to step SP2, and sets the edge position deviation detection result Δr (p, b) and the edge position deviation measurement count n (p, b) to the value 0. Here, the computer 4 calculates the edge misalignment detection result Δr (p, b) for each combination of the pit length p and the pit interval b formed on the compact disc 3, and the number n (p, b) is counted. Therefore, in step SP2, the computer 4 sets all these edge position deviation detection results Δr (p, b) and the edge position deviation measurement count n (p, b) to initial values.
[0021]
Subsequently, the computer 4 proceeds to step SP3, and sequentially compares the digital signal output from the digital oscilloscope 5 with a predetermined slice level, thereby generating a digital binarized signal obtained by binarizing the reproduction signal RF. In this process, the computer 4 binarizes the digital signal so that the value above the slice level is 1 and the value 0 is below the slice level.
[0022]
Subsequently, the computer 4 proceeds to step SP4, and generates a reproduction clock from the binarized signal composed of this digital signal. Here, the computer 4 simulates the operation of the PLL circuit by arithmetic processing based on the binarized signal, thereby generating a reproduction clock (made up of a channel clock).
[0023]
Further, in the subsequent step SP5, the computer 4 samples the binarized signal at the timing of each falling edge of the reproduction clock, and thereby decodes the EFM signal (hereinafter, the decoded EFM signal is referred to as an EFM decoded signal). .
[0024]
Subsequently, the computer 4 proceeds to step SP6 to detect a time difference e from the time of the rising edge of the binarized signal to the time of the falling edge of the reproduction clock closest to this edge, and thereby the edge at this edge is detected. Time measurement of displacement. Subsequently, in step SP7, the computer 4 detects the pit length p and the pit interval b before and after the EFM decoded signal for the edge timed in step SP6.
[0025]
Subsequently, in step SP8, the computer 4 adds the time difference e detected in step SP6 to the edge position deviation detection result Δr (p, b) corresponding to the preceding and following pit lengths p and pit intervals b, and responds accordingly. The edge position deviation measurement count n (p, b) to be incremented by 1 is performed. Subsequently, the computer 4 proceeds to step SP9, determines whether or not the time measurement has been completed for all rising edges, and returns a step SP5 when a negative result is obtained.
[0026]
Thereby, the computer 4 repeats the processing procedure of steps SP5-SP6-SP7-SP8-SP9-SP5, and cumulatively adds the time-measured edge position deviation detection results for each change pattern appearing in the reproduction signal RF. Count.
[0027]
When the time measurement of the positional deviation is completed for all the edges in this way, the computer 4 moves to step SP10 when an affirmative result is obtained in step SP9. Here, for each change pattern appearing in the reproduction signal RF ( That is, for each of the front and rear pit lengths p and pit intervals b), the time-measured edge position deviation detection results are averaged. That is, since the positional deviation detected in step SP6 is affected by noise, the computer 4 averages the edge positional deviation detection results in this way and improves the positional deviation measurement accuracy.
[0028]
After the computer 4 averages the edge position deviation detection result for each change pattern appearing in the reproduction signal RF in this way, the computer 4 proceeds to step SP11 and further averages the detection result for each pit length p. . Subsequently, the computer 4 proceeds to step SP11 and outputs the detection result from the printer 6. Here, as shown in FIG. 3, the computer 4 displays the edge position deviation in a bar graph form for each pit length. In this bar graph, as shown in FIG. 4, the direction in which the pulse width of the binarized signal S2 increases is set to the positive direction.
[0029]
When the positional deviation is detected with respect to the rising edge in this way, the computer 4 proceeds to step SP13 and ends this processing procedure. Subsequently, the computer 4 similarly performs a positional deviation detection process for the falling edge, and outputs a detection result as shown in FIG. In FIG. 5 as well, as shown in FIG. 6, the computer 4 sets the direction in which the pulse width of the binarized signal S2 increases to the positive direction and outputs the detection result, as in the case of the rising edge. .
[0030]
In addition, when the operator switches the output mode after detecting the edge misalignment for both the rising edge and the falling edge in this way, the rising edge and the falling edge for each pit length. Are added and displayed as shown in FIG.
[0031]
In this way, the positional deviation is detected in this way, and the edge of the binarized signal corresponds to the edge of the pit formed on the compact disk 3. As a result, the computer 4 detects the edge misalignment of the EFM decoded signal in this way, and deforms the pits formed on the compact disc 3 on the basis of the recording basic period T corresponding to the reproduction clock. For each pit length, both the front edge and the rear edge are measured.
[0032]
In the configuration described above, the compact disc 3 (FIG. 1) is configured such that the disc master is sequentially exposed by turning on and off the laser beam with a modulation signal whose signal level changes in a cycle that is an integral multiple of the basic cycle T, and pits are formed. A metal mask, a mother disk, and a stamper are sequentially formed from this disk master, and are then formed from this stamper by a production method such as injection molding or the 2P method. The compact disc 3 is formed by changing the positions of the front edge and the rear edge as compared with the timing according to the basic period T due to various conditions at the time of creation.
[0033]
The compact disc 3 produced in this way is reproduced by the compact disc player 2 to generate a reproduction signal RF whose signal level changes according to the amount of return light, and this reproduction signal RF is digitally converted by the digital oscilloscope 5. Converted to a signal. In the compact disk 3, a digital signal is binarized by a slice level that is a predetermined reference level in the computer 4, a binarized signal is generated, and a reproduction clock is reproduced from the binarized signal. Further, the compact disc 3 latches the binarized signal by the reproduction clock and generates an EFM decoded signal.
[0034]
Further, the compact disc 3 detects the pits and lands before and after the EFM decoded signal for each edge of the binarized signal to detect the change pattern of the EFM signal. For each change pattern, the edge of each edge relative to the reproduction clock is detected. The positional deviation is time-measured with the direction in which the pit shape is enlarged set as the positive side.
[0035]
Further, these time measurement results are averaged for each change pattern, and then classified and averaged for each pit length, rising edge, and falling edge, and the averaged measurement results are output from the printer 6. The As a result, in this compact disc 3, it is possible to evaluate the deformation of the pits more easily and in detail than in the past, thereby correcting the pressure, temperature, etc. of the injection molding to shorten the manufacturing process conditions. It can be converged in time.
[0036]
According to the above configuration, the timing at which the signal level of the reproduction signal crosses the predetermined reference level is measured with reference to the reproduction clock, and the time measurement result is classified by pit length, rising edge, and falling edge. By counting, the shape of the pit formed on the compact disc can be evaluated easily and in detail. This makes it possible to converge the manufacturing conditions in a short time by applying to the manufacturing process of the compact disk.
[0037]
(2) Second Embodiment FIG. 8 is a process diagram showing an evaluation process of a compact disk according to a second embodiment. In this evaluation process, the compact disc 11A created by the 2P method and the compact disc 11B created by the injection molding method are evaluated, and the difference between these two manufacturing steps is evaluated by comparing the evaluation results.
[0038]
That is, in this evaluation process, the edge position deviation is detected for each pit length in the compact disc 11A created by the 2P method and the compact disc 11B created by the injection molding method by the optical disc evaluation apparatus 1 described above with reference to FIG. To do. Further, by subtracting the edge position deviation amount for each pit length between the detection results 12A and 12B, a comparison result 13 between the detection results 12A and 12B is obtained, and this comparison result is output from the printer 6.
[0039]
According to the configuration shown in FIG. 8, the difference between the manufacturing process of the 2P method and the manufacturing process by the injection molding method can be detected easily and in detail, and the manufacturing variation due to the difference between these manufacturing processes can be easily and quickly performed. Can be converged to.
[0040]
(3) Other Embodiments In the above-described embodiment, the case where a binarized signal is generated from a reproduced signal and the edge timing of the binarized signal is detected with reference to the reproduced clock has been described. However, the present invention is not limited to this, and the edge position deviation may be measured by directly measuring the timing at which the signal level of the reproduction signal crosses the threshold value for generating the binary signal.
[0041]
Further, in the above-described embodiment, the case where the binarized signal, the reproduction clock, and the EFM decoded signal are generated by the arithmetic processing in the computer has been described. However, the present invention is not limited to this, and for example These signals used for processing may be used, and a dedicated signal processing circuit may be configured.
[0042]
In the above-described embodiment, the case where the pit shape is simply evaluated for each pit length has been described. However, the present invention is not limited to this. For example, the compact disc 3 is divided into an inner peripheral region and an outer peripheral region. The pit shape may be evaluated for each pit length for each region. In this way, detailed evaluation criteria can be obtained for the resin flow during injection molding.
[0043]
Furthermore, in the above-described embodiment, the case of evaluating a compact disk has been described. However, the present invention is not limited to this, and may be used for evaluating a metal mask or the like.
[0044]
Furthermore, in the above-described embodiment, the case where the disk evaluation apparatus according to the present invention is applied to the manufacturing process of the compact disk and the compact disk is evaluated has been described. The recording characteristics of these optical disk devices can be evaluated by using them for evaluating various recorded optical disks.
[0045]
In the above-described embodiment, the case where the present invention is applied to the evaluation of a compact disk has been described. However, the present invention is not limited to this, and is widely applied to the evaluation of an optical disk apparatus that records various data using pits and marks. can do. Incidentally, the present invention can be widely applied to an optical disc apparatus adapted to record various data in a multi-valued manner due to a difference in transient response characteristics of a reproduction signal.
[0046]
【The invention's effect】
As described above, according to the present invention, the timing at which the signal level of the reproduction signal crosses a predetermined reference level is time-measured with reference to the clock, and the time measurement results are aggregated for each recording pattern, so that the optical disc is recorded. Simple and detailed evaluation is possible.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an optical disk evaluation apparatus according to a first embodiment of the present invention.
FIG. 2 is a flowchart showing a processing procedure of a computer in the optical disk evaluation apparatus of FIG.
3 is a characteristic curve diagram showing an output of a measurement result by the optical disk evaluation apparatus in FIG. 1. FIG.
4 is a signal waveform diagram showing polarity in the measurement result of FIG. 3;
FIG. 5 is a characteristic curve diagram showing an output of a measurement result of a falling edge shown corresponding to FIG. 3;
6 is a signal waveform diagram showing polarity in the measurement result of FIG.
FIG. 7 is a characteristic curve diagram showing the output of measurement results, which is a synthesis of measurement results of rising edges and falling edges.
FIG. 8 is a process diagram showing an optical disk evaluation process according to the second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical disk evaluation apparatus, 2 ... Compact disk player, 3, 11A, 11B ... Compact disk, 4 ... Computer, 5 ... Digital oscilloscope, 6 ... Printer

Claims (6)

An optical disk evaluation device,
The optical disc is
Depending on the data to be recorded, the laser beam is turned on and off by a period that is an integral multiple of a predetermined basic period, and the data is recorded on a disk-shaped recording medium.
The optical disk evaluation apparatus comprises:
Clock reproduction means for reproducing the clock of the basic period from a reproduction signal obtained from the optical disc;
Based on the timing at which the signal level of the clock is switched, the timing at which the signal level of the reproduction signal crosses a predetermined reference level is measured, so that the timing of the clock is referenced with respect to the pits formed on the optical disc. A time measuring means for detecting edge position deviation and outputting a position deviation detection result ;
An optical disk evaluation apparatus comprising: a totalizing unit that classifies and totals the edge displacement detection results for each of the pit lengths . The counting means includes
2. The optical disk evaluation device according to claim 1, further comprising: classifying the edge misalignment detection results by classifying the adjacent lands into different lengths . The aggregation means is
2. The optical disk evaluation apparatus according to claim 1, wherein the edge displacement detection results obtained by the time measuring means are added or averaged, and the edge displacement detection results are totaled . The counting means includes
3. The optical disk evaluation apparatus according to claim 2, wherein the edge displacement detection results obtained by the time measuring means are added or averaged, and the edge displacement detection results are totaled . The counting means includes
The apparatus for evaluating an optical disk according to claim 1, wherein a comparison result between tabulated results obtained from different optical disks is output. An optical disk evaluation method,
The optical disc is
Depending on the data to be recorded, the laser beam is turned on and off by a period that is an integral multiple of a predetermined basic period, and the data is recorded on a disk-shaped recording medium.
The evaluation method of the optical disc is:
Reproducing the clock of the basic period from the reproduction signal obtained from the optical disc,
By measuring the timing at which the signal level of the reproduction signal crosses a predetermined reference level with respect to the clock, the edge misalignment of the pits formed on the optical disk is determined with reference to the timing of the clock. To detect the displacement detection result ,
For each pit length, the edge misalignment detection results are classified and tabulated to obtain a tabulated result,
Determining a difference between the manufacturing processes related to the first and second optical discs based on a comparison result between the aggregation result obtained for the first optical disc and the aggregation result obtained for the second optical disc. An optical disk evaluation method characterized by the above.

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