JPS62295273A - Signal reproducing method - Google Patents

Abstract

PURPOSE:To expand the data read enable range without lowering the reliability of data reproduction by comparing plural data including data before correction processing and adopting the coincident data as an effective data in reproducing the data recorded by n-multiple write and when the data obtained by error detection or correction does not satisfy a prescribed data adopting condition. CONSTITUTION:In reproducing a data signal recorded on a recording medium by n-multiple (n is an integer over 2) such as an address of each sector of the optical disk, the n-multiple written data is reproduced and subject to error detection or correction, and the result does not satisfy a prescribed data adopting condition, then the n-multiple written reproducing data is compared together with the data before correction, and when the coincidence is detected, it is adopted as an effective data. Thus, the data read enable range is expanded without deteriorating the reliability of data reproduction.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention A. Field of Industrial Application The present invention is for reproducing data signals such as addresses recorded in multiplex on a recording medium such as an optical disk or an optical card. Regarding the method.

B0 Summary of the Invention The present invention provides an address system for each sector of an optical disk.
When reproducing a data signal that has been overwritten (n is an integer of 2 or more) and recorded on a recording medium, the result of reproducing n overwritten data and performing error detection or correction processing is the predetermined data adoption condition. When the above is not satisfied, the readable range of the data is increased without deteriorating the reliability of data reproduction by comparing the n-overwritten reproduced data including the data before correction, and if a match is detected, it is adopted as valid data. Expand.

C1 Conventional technique fti In recent years, recording media with extremely high recording densities, such as optical recording media such as optical disks and optical cards, have been put into practical use. In this case, the frequency of burst errors and random errors is increasing, so especially important data, such as the address data of each sector of the optical disk, the user registration number or PIN number of the optical card, etc. The same data is written multiple times over and over again.

That is, for example, concentric or spiral tracks are formed on a disk-shaped optical recording medium such as an optical disk or a magneto-optical disk, and one trunk is divided into a plurality of sectors. For example, at each predetermined position, for example, at the beginning position, so-called formatting processing is performed before starting to use a new disk.
Due to a so-called preformatting process performed by the disc supplier, a set of addresses and error detection or error correction codes is recorded, for example, in triplicate.

D0 Problems to be Solved by the Invention By the way, when reproducing and reading important data recorded n times (n is an integer of 2 or more) on such a recording medium, each of the n times written Decoding processing such as error detection and error correction is performed on each reproduced data signal, and each corrected data that has been determined to be error-free due to this correction etc. is compared with each other, and based on so-called majority logic, the most common error is determined. The data was accepted as valid. However, for example, in order to prevent correction errors (erroneous corrections) in the above-mentioned error correction processing, etc., correction is performed only when the number of errors is sufficiently smaller than the upper limit of correction ability, or when two or more of the decoded data There are certain conditions for accepting valid data, such as not accepting it as valid data unless there is one defeat, and if this condition is not met, it is judged as a data reading error and a retransmission request is issued. It is normal for the process to proceed as follows.

Therefore, in a system with a low error rate, data reading errors occur frequently, and data that should be read correctly may not be read, which has the negative effect of reducing data reading efficiency.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a signal reproducing method that can expand the readable range of data without reducing the credibility of data reproduction.

Means for Solving the E1 Problem In order to solve the above-mentioned problem, the signal reproducing method according to the present invention has the following advantages:
In a signal reproducing method for reproducing a recording medium recorded with overwriting (n is an integer of 2 or more), data obtained by reproducing the data recorded with n overwriting and performing error detection or correction processing. The present invention is characterized in that when data does not satisfy predetermined data adoption conditions, a plurality of data including data before correction processing are compared with each other, and data is adopted as valid data depending on whether the data is defeated or not.

10 Effects By comparing multiple pieces of reproduced data, including data before correction, for data for which error correction has not been performed, data that was previously not considered valid may be adopted, making the data readable. The range can be expanded.

G. Embodiment Next, prior to explaining the present invention, address data of each sector of an optical disc will be explained as an example of multiple writing data of a recording medium to which the present invention is applied.

That is, FIG. 1 is a diagram for explaining a specific example of a signal recording formant on an optical disk as an example of an optical recording medium. In FIG. 1, one track on an optical disc is linearly stretched out, and the identification section (so-called ID section) of one sector is schematically shown enlarged. One track consists of a plurality of sectors, and one sector consists of, for example, a preformatted identification section IDR and a data section DTP as an area in which m sector data are recorded. At the beginning of the identification section IDR, a recording section for a synchronization signal (PLO sync) PLO3 for stabilizing the operation of the clock generation PLL circuit, etc. when reading data is placed at the beginning! The unit UT, which is one recording unit of sector identification address information, is arranged in triple writing (n=3>) consecutively to the recording part of this synchronization signal PLO3. Three units with the same content that serve as recording units: UTI, UT2, UT
3 are arranged sequentially following the synchronization signal PLOS, and each recording unit or unit UT is arranged with an address mark SP of the sync pattern at the beginning, and an address AD consisting of a track address TA and a sector address SA. Next, an error correction code ECC consisting of a CRC error detection code or a BCH code, for example, is arranged.

Here, as an example of the number of bits in each part, the address AD is 24 bits in total, consisting of 16 bits for the track and quad addresses TA and 8 bits for the sector address SA, and the length of the error detection or correction code ECC is , and has 24 bits, which is equal to the address AD.

When recording or reproducing data signals on an optical disk having sectors (blocks) in such a recording format, for example, by using a host combination, the block ( sector) is required. In order to access the sector of this target address, conventionally, when reading the address by reproducing the identification part < rD part of each sector, error detection or correction is performed for each address AD of each unit tJT1 to UT3. Detected or corrected with code ECC and compared with each other, those that are determined to be no errors,
If these address values are different, the majority logic determines the address value that matches the most (in the case of triple writing, 3
The address value in which two of the two address values match is used as the valid address of the current location.

However, with this method, if the number of errors in the reproduced address is large and cannot be corrected, or if the corrected addresses are all different, the valid address cannot be determined by majority vote, and it must be determined that an address detection error has occurred. I don't get it.

Therefore, in the present invention, these addresses are compared with each other, including not only addresses that were found to have no errors through the above-mentioned error detection and correction processing, but also addresses that were detected to have errors and addresses that could not be corrected. However, by adopting this as a valid address when a loss is posted, data that was previously not considered valid can now be adopted, broadening the conditions under which data can be read and expanding the effective reading range. It is possible.

Next, a specific example of an operation for reproducing such multiple-written data such as an address and employing it as valid data will be described.

Here, Figure 2 shows a recording unit (unit U) consisting of important data such as the above address and error detection or correction code
This shows a simplified reproduction signal (omitting the sync pattern, etc.) when a file T) recorded with n-fold writing (for example, double-writing) is reproduced. In this example, the double aged units) UTI, UT2 are regenerated, each with 24 bits of data and error correction or error 1) Ml(DI, El), (D2, E2)
The order is in order and the order is in order.

Now, assume that error correction codes are used as codes E1 and E2, and for 24-bit data DI (or D2) (if it is encoded with an extended BCH code of 48, 24>, 5 bits/) However, when correcting a 5-bit error, which is the limit of this error correction ability, the probability of a correction error (correction error, erroneous correction) occurring increases, and the reliability of the corrected address becomes Therefore, the correction process is performed only when the number of errors is three or less. This can be done by, for example, assigning a weight W as shown in Table 1 below depending on the number of errors, and determining whether to use valid data while taking this weight into consideration.

Table 1 An example of a specific operation for employing valid data in consideration of such a weight W will be described with reference to FIG. Wl and W2 in FIG. 3 indicate the weights determined from Table 1 above according to the number of errors in the reproduced data of each unit U1 and U2, and as a specific example, the weight W is When the weight W is 6 (no error), the reproduced data is adopted as is, when the weight W is 3 to 5, error correction processing is performed, and when the weight W is 2 or less, error detection is performed only without correction, considering that reliability is low. That's what I do.

That is, first, in step S1 of FIG. 3, the weight wl is calculated from Table 1 above according to the data DI" obtained by reproducing the unit UT1 and the number of errors in the error correction code E1, and similarly, These calculations are performed on the reproduced data of unit UT2 in step Sll.

After the weight Wl is calculated in step S1, step S
In Step 2, it is determined whether the weight Wl is 6, that is, whether the reproduced data D1 and the origin of the error correction code El are no errors.
The playback data D1 is processed as valid data DTSL.
Adopt. That is, when there is no error, the reproduced data D1 is adopted as is and the operation is ended. Step S
If the determination in step S2 is NO, the process advances to step S4.
It is determined whether the weight Wl is 3 or more and 5 or less (3≦W1≦5), and if YES, error correction decoding processing (
After calculating the correction data Dlc by performing decoding processing), the process proceeds to the next step 311. Further, when the determination in step S4 is NO, the process proceeds to step S6, and the reproduced ° data D as is without error correction.
I is used as data Dlc for comparison which will be described later, and the process proceeds to the next step Sll.

In the specific example of FIG. 3, steps S1 to S6
The routine up to this point operates similarly to the routine from steps 311 to 316, except that the units to be reproduced are different, and each step 81 to S6 corresponds to steps 311 to 316, respectively. Therefore, in step S15, corrected comparison data D2c is calculated based on the reproduced data D2 and E2, and in step S1
In No. 6, the reproduced data D2 is directly used as comparison data D2c without error correction.

Next, in step S21, each of the above calculated times W
The maximum value Wmax of l and W2 is detected, and the process proceeds to the next step 322, where it is determined whether the maximum value -max is equal to 5 or not. When it is determined as YES in step S22, 5 of the maximum value Wmax is equal to Wl for each of the above times.
, W2, the process advances to the next step S23 to determine whether or not Wl is 5. If YES, the process advances to step 324 to determine the valid data D.
The above comparison data Dlc is adopted as TSL and the operation is ended. When Wl is not 5, W2 is 5, so the process advances to the next step S25, employs the comparison data D2c as the valid data DTSL, and ends the operation. Next, if the determination in step 322 is NO, the process proceeds to step 1326, where the comparison data D
It is determined whether lc and D2c match each other. Y
When ES, that is, these data Dlc and D2C
When they match each other, the comparison data Dlc (=
D2c) is adopted to end the operation. Step S26
If it is determined No, the reliability is low and the data is inappropriate as valid data, so the process proceeds to step 328 and the operation ends without using the reproduced data. Rather than accepting incorrect data as valid data, it is better to treat it as a data detection error and move on to the next process (for example, read it again, eliminate it as a defective part and prevent it from being recorded, etc.). This is because there are fewer negative effects.

Through the above operation, even if the above weight is 4 or less for both data (the number of errors is 2 or more) for the two data obtained by reproducing the double-written data, the data will not be corrected. If both systems lose one match, the data will be accepted as valid data, and the effective reading rate of the data can be increased even in a system with a low error rate.

The above specific example is an example using an error correction code, but C
The present invention can also be applied when an error detection code such as RC is used.

That is, in FIG. 4, the symbol El (and E2) in FIG.
) shows a specific example of valid data adoption operation when a CRC error detection code is used.

In step S41 of FIG. 4, the above unit)
Error detection processing, so-called CRC check, is performed based on the data D1 obtained by reproducing the UTI and the CRC error detection code E1. After error detection is performed in step S41, in step S42! It is determined whether or not the result of the iRC check is no error. If YES, the process proceeds to step S43 and the reproduced data Di is adopted as valid data DT, L. That is, when there is no error, the reproduced data D1 is adopted as is and the operation is ended.

When the determination in step S42 is No, the process proceeds to step S44, and the same process as in step S4 above (CR
C check) is performed on the reproduced data of unit UT2, and then the process proceeds to step S45, where it is determined whether there is no error. When YES (when there is no error)
In this case, the process advances to step S46 and the valid data DTSL
The operation is terminated by adopting the reproduction data D2 as N.
If it is determined as o, the process advances to step S47. In step S47, it is determined whether the reproduced data D1 and D2 match each other. When YES, that is, when these data D1 and D2 are mutually defeated, the comparison data Di (=D2) is set as valid data D T 'S L in step 34B, considering that there is an extremely high possibility that the data are correct. Recruit and end the operation. When it is determined No in step S47, the reliability is low and the data is inappropriate as valid data, so the process proceeds to step 349 and the operation ends without using the reproduced data.

According to such an operation, even double-written data that was once rejected by a CRC check can be determined to be correct with relatively high reliability if they match, and the effective readable range is expanded. That will happen.

Note that the present invention is not limited to the above-mentioned embodiments, and can be applied to card-shaped recording media such as optical cards in addition to disc-shaped recording media. The recording format of the identification section (ID section) of the track is also not limited to the illustrated example.

H0 Effects of the Invention The signal reproducing method of the present invention makes it possible to read data that was considered unreadable in the past despite its relatively high reliability, expand the readable range of data, and reduce the error rate. Even in a bad system, deterioration of signal reproduction efficiency can be prevented, and signal reproduction can be realized in accordance with the actual situation.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a signal recording format on an optical disk used in an embodiment of the present invention, FIG. 2 is a diagram showing an example of double-written data for explaining the present invention in detail, and FIG. Figure 3 is a flowchart for explaining the valid data adoption operation when error correction code is used, and Figure 4 is CRC.
12 is a flowchart for explaining valid data adoption operation when an error detection code is used.

Claims (1)

[Claims] A set of data and an error detection or correction code is written in n-fold (
n is an integer of 2 or more), the data obtained by reproducing the data recorded with n overwriting and performing error detection or correction processing is used as a predetermined signal. 1. A signal reproducing method characterized in that when data adoption conditions are not satisfied, a plurality of data including data before correction processing are compared with each other, and the data is adopted as valid data depending on the data matching.