JP3585480B2 - Device for detecting the position and length of recording / reproducing errors on rewritable optical discs - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus for detecting the position and length of a recording / reproducing error of a rewritable optical disk.
[0002]
[Prior art]
In the defect evaluation of an optical disk, a slice level is provided in a reproduced signal from the disk, and a signal exceeding this level is extracted as a defect. In addition, after writing a signal on the optical disk even if an error occurs, the reproduced signal is compared with the write signal, and a part that does not match is extracted as an error.
[0003]
Most importantly when manufacturing and inspecting optical disks, there are some defects on the disk and how much error it would have if the data was actually written.
[0004]
Here, values such as an error rate and a defect rate are used as indices expressing these, and the quality of the disc is determined based on the values.
[0005]
These are expressed by the following equations.
[0006]
Defect rate = number of defects / (number of data bits that can be recorded within the measurement range)
Error rate = Number of errors / (Number of recordable data bits within the measurement range)
In addition, as a well-known technique, for example, the following Patent Document 1 can be cited.
[0007]
[Patent Document 1]
Japanese Utility Model Laid-Open No. 1-24464
[Problems to be solved by the invention]
It should be noted here that the size of the defect and the size and length of the error are ignored in these equations. In most cases, the actual defect has a pinhole or foreign matter on the disk. For this reason, defects usually have a length originally. In the defect measurement, a slice is provided in the reflected signal from the optical disk, and a signal exceeding the threshold value is counted as a defect. For this reason, there is no problem if one defect signal is output from one defect, but in reality, a plurality of defect signals may be output from one defect. In this case, it is clear that the defect rate rises from the above equation, and shows a value far from the actual number of defects.
[0009]
On the other hand, when an error occurs due to the influence of the above-described defect, the error occurs over several bits. However, even if an error occurs over several bits, a plurality of errors do not occur during actual data reproduction. The reason is that the optical disk device has a strong error correction function such as ECC and CRC, so that a continuous error having a length of several bits results in one error, but data can be read without any problem during actual reproduction. Because. However, when errors are measured by the above-described inspection method, since each compare check is counted as one error, it is likely that more errors are generated than actual recording / reproducing errors. There was a problem that was displayed on the.
[0010]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an apparatus capable of accurately detecting the position and length of a recording / reproducing error of a rewritable optical disk.
[0011]
[Means for Solving the Problems]
An object of the present invention is to provide a device for detecting the position and length of a recording / reproducing error of a rewritable optical disk, a comparator for comparing reproduced data from the optical disk with recorded data, and a position information and length of the reproduced data. A counter circuit for calculating information; an output result from the comparator; and an error position detection circuit for detecting position information of the recording / reproducing error from an output result from the counter circuit. An arithmetic circuit for calculating an output result, a circuit for recognizing a track or a sector, and a control circuit for an optical head are provided, and an arithmetic circuit for calculating an output result of the error position detection circuit includes a first error detection circuit. Weighting is performed before and after to expand the error range, and if there is another error within this range, the error is connected and the error range is expanded even if the error range is expanded. If another error within, can be achieved by eliminating the weighting has a function of the final error.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
One embodiment of the present invention is shown in FIG. In FIG. 1, 1 is an optical disk (recording surface), 2 is an autofocus lens for collecting light on the recording surface of the optical disk, 3 is a polarizing beam splitter for separating reflected light and incident light, and 4 Is a lens that converts laser light into parallel light, 5 is a λ / 2 plate that rotates the plane of polarization, 6 is a beam shaping prism, 7 is a polarization beam splitter that splits light into two, and 8 is a detector that detects reflected light , 9 are semiconductor lasers, 10 is an addition amplifier for forming a sum of reflection signals, and 11 is a reflection signal (RD signal) added by the addition amplifier 10.
[0013]
In FIG. 2, reference numeral 12 denotes a binarizing circuit for generating a binarized signal from the RD signal 11, 13, 13 comparator circuits for detecting a defect from the RD signal 11, 14 and 14 slice circuits for determining a slice level of the comparator 13, Reference numeral 15 denotes a synchronizing signal detection circuit for detecting a synchronizing signal or an amplified signal contained in the header from the binarized signal, 16 an OR circuit for ORing a bright defect signal and a dark defect signal, and 17 a count from AM1. A counter circuit for generating defect position information, a defect position generating circuit for adding address information in a sector to the defect detection signal from the OR circuit 16 and generating defect raw data, and a defect circuit for generating defect raw data. The CPU is a CPU that generates raw defect data based on the obtained data, weights the raw data, and determines and executes whether or not to perform connection. In addition, the evaluation apparatus recognizes tracks and sectors from servo circuits and binary data of the AF servo system, TR servo system, course system, laser control system, spindle servo system, etc., and generates optical heads. It is assumed that it has a control circuit and the like for moving.
[0014]
In FIG. 1, a reflected signal from the optical disk 1 is converted into an electric signal by a detector 8, amplified by an addition amplifier 10, and detected as an RD signal 11.
[0015]
FIG. 3 shows a state where slices are sliced above and below the RD signal 11 to extract defects. The detection signal (defect signal) is represented as 20. The defect signal 20 allows the size and position of the defect to be known from the counter from AM1.
[0016]
These are represented in the figure by the numbers below the 20 signal lines. For example, the defect in FIG. 4 indicates that when AM1 is 0, it appears from 10 bits to 11 bits, and then appears from 14 to 15. By processing this, it can be seen that both the defect lengths are 1 bit. These processes are performed by the CPU 19.
[0017]
Weighting processing is performed by software based on the defect raw information. FIG. 4 shows a conceptual diagram of the weighting process. As shown in the figure, the first defect is weighted. Weighting first expands the defect width to a few bits before and after the previous defect. For example, if there is a defect of 10 to 11 bits and weighting of 4 bits is performed, the defect is in a range of 6 to 14 bits. At this time, if there is another defect within this range, it is assumed that this is from a defect on one disk, and the defect is connected. In this case, since there is a defect in 14 to 15, connection is performed, and it is assumed that 10 to 15 have a defect. As a result, the defect length also becomes 5 bits.
[0018]
Similarly, in the case of FIG. 5, the defect is expanded, but since there is no defect before and after, the defect is eventually a defect 30 to 31 as one isolated defect. This operation is sequentially performed each time a defect appears. Linking the defects in this manner reduces the total number of defects and consequently the rate from the defect rate equation. However, as described above, the defect rate has no concept of length and provides a defect rate corresponding to a defect on an actual disk. By linking the defect data in this manner, the size and position of the defect can be found in the same form as the defect on the disk, and the defect rate corresponding to the true state of the disk can be calculated.
[0019]
FIG. 6 shows another embodiment of the present invention. The same portions as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted.
[0020]
Reference numeral 30 denotes a magneto-optical signal (RD signal) obtained by the addition amplifier 10, 21 denotes a WR power control system for writing data on the optical disk 1, 22 denotes a WR pattern generator that generates a WR pattern, and 23 denotes a differential. A differentiating circuit for generating a differential signal from a signal, 24 is a binarizing circuit for generating a binarized signal from the differential signal, 25 is a data extracting circuit for identifying a data area, 26 is a WR data and RD data are compared to extract an error. An error extractor, 27 is a counting circuit which starts counting from AM1 in the pre-pit, 28 is an error position detecting circuit which generates an error position signal from the error signal and the value of the counter, and 29 is an error weighting and connection based on the error position signal. CPU. In addition, the present evaluation apparatus recognizes tracks and sectors from binarized data and moves the optical head by using servo circuits such as an AF servo system, a TR servo system, a course system, a laser control system, and a spindle servo system. Assume that it has a control circuit and the like.
[0021]
In FIG. 6, the reflected signal from the optical disk 1 is converted into an electric signal by the detector 8, amplified by the addition amplifier 10, and detected as the RD signal 30. It is output as shown in FIG. FIG. 7 shows how the RD signal 30 is compared with the comparator signal to extract an error. The detection signal is represented as 31. The error signal 31 allows the magnitude and position of the error to be known from the counter from AM1. These are shown by the numbers below the signal line of the error signal 31 in FIG. For example, the error shown in FIG. 8 indicates that when AM1 is set to 0, it appears from 66 bits to 67 bits, and then from 68 to 69 appears next, next, and next. By processing this, it can be seen that the error length is all one bit. These processes are performed by the CPU 29. Weighting processing is performed by software based on the raw error information.
[0022]
The concept of the weighting process is shown in FIG. First, the first error is weighted. Weighting first expands the error width to a few bits before and after the previous error. For example, if there is an error between 66 bits and 67 bits and weighting is performed for 4 bits, the error will be between 62 bits and 71 bits. At this time, if there is another error within this range, it is assumed that the error originates from a defect on one disk and the error is connected. In this case, since there is an error from 68 to 71, connection is performed, and it is assumed that there is an error from 66 to 71. As a result, the error length also becomes 3 bits. Next, when this error is further weighted, the error becomes 75. And if there is another error here, it will be connected. Thereafter, this operation is continued in order, and finally, there is one error having a length of 9 bits.
[0023]
By linking the error data in this manner, the magnitude and position of the error can be known in the same form as the defect on the disk, and the error rate corresponding to the true state of the disk can be calculated. This has the effect of enabling more actual disk evaluation.
[0024]
The disc is effective not only for the magneto-optical disc but also for other phase-change optical discs.
[0025]
【The invention's effect】
The present invention is configured as described above, and can accurately detect the position and length of a recording / reproducing error of a rewritable optical disk.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a former part of an embodiment of an optical disk defect detection circuit according to the present invention.
FIG. 2 is a configuration diagram of a rear part of an embodiment of an optical disk defect detection circuit according to the present invention.
FIG. 3 is a timing chart of optical disk defect detection according to the present invention.
FIG. 4 is a timing chart of optical disk defect detection according to the present invention.
FIG. 5 is a timing chart of optical disk defect detection according to the present invention.
FIG. 6 is a configuration diagram of an embodiment of an optical disk error detection circuit according to the present invention.
FIG. 7 is a timing chart of optical disk error detection according to the present invention.
FIG. 8 is a timing chart of optical disk error detection according to the present invention.
[Explanation of symbols]
Reference Signs List 1 optical disk 10 addition amplifier 12 binarization circuit 13 comparator circuit 14 slice circuit 15 synchronization signal detection circuit 16 OR circuit 17 counter circuit 18 defect position generation circuit 19 CPU
Reference Signs List 21 WR power control system 22 WR pattern generator 23 Differentiator circuit 24 Binarization circuit 25 Data extraction circuit 26 Error extractor 27 Count circuit 28 Error position detection circuit 29 CPU

Claims (1)

In a device for detecting the position and length of a recording / reproducing error of a rewritable optical disk,
A comparator for comparing read data and recorded data from the optical disk;
A counter circuit for calculating position information and length information of the reproduction data;
An output result from the comparator, and an error position detection circuit that detects the position information of the recording / reproducing error from the output result from the counter circuit;
An arithmetic circuit for calculating the output result of the error position detection circuit;
A circuit that recognizes tracks and sectors,
An optical head control circuit ,
An arithmetic circuit for calculating the output result of the error position detection circuit performs weighting before and after the first error to increase the width of the error, and if there is another error within this range, connects the errors. If there is no other error within the range even if the width of the error is expanded, the weighting is eliminated and a final error is provided. A device that detects position and length.

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