JP2002032966A - Information reproducing method and information reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an information recording method and an information reproducing method capable of enhancing the reliability of data by increasing the correction capability in the burst error of recorded data to be generated by the defect, dust and scratch of a disk. SOLUTION: This reproducer is enabled to perform error correction by using data in an error correction block and error correcting codes dispersed in plural sectors in the error correction block for every correction block and to increase the length of burst error correction by dispersing and arranging the error correcting codes which are generated with respect to the set of data collected from respective sectors included in the error correction block by every prescribed number into plural sectors in the error correction block.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting information errors in an apparatus for recording and reproducing information on a disk-shaped recording medium, and more particularly to an information reproducing method and an information reproducing apparatus. Is what you do.

[0002]

2. Description of the Related Art An optical disk has been used as a new means for recording large-capacity information. Optical discs record and reproduce information using changes in the rotation angle of light due to the magneto-optical effect and differences in reflectance due to differences in heating temperature.
A rewritable non-rewritable (ROM) disk can be easily manufactured, and has a feature that information can be reproduced in a recording / reproducing apparatus for the rewritable disk. This feature makes it possible to distribute large amounts of information at low cost, and has been established in international standards as an important technology in the multimedia age.

[0003]

However, an optical disk has a higher error rate than a conventional magnetic disk and is premised on the use of an error correction code. The types of error occurrence on the optical disc are classified into random errors and burst errors. The random error is caused by noise or the like, and an error occurs in a bit unit. A burst error is caused by a defect, dust, or scratch on a disk, and erroneous consecutive bits.

[0004] Fig. 6 shows the structure of a sector on an ISO standard 3.5 "optical disk. A sector 10 is composed of 512 bytes of user data, 4 bytes of vendor unique data, 4 bytes of an error detection code (CRC) by a cyclic code, and 4 bytes of read / write. The error correction code (ECC) parity of the Solomon code is composed of 80 bytes, and the generation sequence of the error correction code is divided into a total of 520 bytes of user data, vendor unique data, and CRC into 104 bytes every 5 bytes. A 16-byte ECC parity is generated, and five error correction sequences are formed in the entire sector (5 interleaves). It can correct up to eight-byte errors, and can correct 40-byte errors in the entire sector. , For the burst error, in one sector, it has a correction capability of the continuous 40 byte.

However, in an actual optical disk, a random error and a burst error occur simultaneously, and a burst error within a correction range is fixedly generated. When a random error occurs therein, the number of random errors is reduced by the correction range. Even within, the result is that correction is impossible.

Therefore, it is necessary to eliminate fixed burst errors as much as possible during data recording. Therefore, a rewritable disk device employs a method of rewriting data in another location when an error at the time of information reproduction immediately after recording exceeds a predetermined number even within the range of error correction capability.

However, such a rewrite cannot be performed on a ROM disk in which information is recorded in pre-pits at the time of manufacture of the disk. Therefore, according to the ISO 3.5 ″ standard, one parity sector is provided for every 25 sectors, and the parity sector is located at the same position in each sector. Exclusive OR (EO) of certain data for each byte
R) is performed and recorded in the parity sector. However, in this parity system, the recording efficiency is reduced because a parity sector is required separately from the data sector, and since only one byte error can be corrected in one correction sequence, a burst error and a random error are combined. When the error occurs, the error tends to be uncorrectable, and a higher error correction capability is required.

[0008]

In order to solve the above-mentioned problem, in the present invention, an error correction code sequence is dispersedly arranged between sectors which are blocks of information recording. The playback device has a storage unit for storing data of a plurality of distributed sectors and a correction unit.

As another means, two systems are provided: a sequence in which error correction code sequences are arranged in a distributed manner within a sector, and a system in which error correction code sequences are arranged in a distributed manner between sectors. In the reproducing apparatus, storage means for storing data of a plurality of sectors, first error correction means for correcting data distributed in a plurality of sectors, and second means for correcting data distributed in a sector.
Error correction means. Alternatively, it has one error correction circuit for sequentially performing correction of data dispersed in the sector and correction of data dispersedly arranged between the sectors.

[0010]

The data sequence for generating the error correction code is composed of 0 sector, 1 sector, 2 sectors... N sector, 0 sector,.
The data is used one byte at a time, and the generated error correction code is also recorded on the recording medium following the data.
In the reproducing apparatus, reproduced data from sector 0 to sector n is stored in the storage unit, and the data and the error correction code are read out from the storage unit in the same order as when the error correction code was generated, and the error correction unit corrects the data. The corrected data is read from the storage unit in the order of the sectors and output to the host device.

In addition, an error correction code is generated based on the data in the sector, and the generated error correction code is recorded in the same sector. In the reproducing apparatus, the reproduced data from sector 0 to sector n is stored in the storage means, and the data and error correction code in each sector are read out from the storage means, and the correction in the sector is performed.

After performing the correcting operation for all the sectors, the data and the error correction code of the data series distributed between the sectors are
0 sectors, 1 sector, 2 sectors... N sectors, 0 sectors... By performing double error correction on 1-byte data, the correction capability is improved. Or 0
Error correction within the sector is performed while data from the sector to the n-th sector is stored in the storage means. When an error that cannot be corrected occurs, error correction between the sectors is performed.

[0013]

The present invention will be described below with reference to examples. Figure 1
FIG. 1 shows a first example of a sector configuration according to the present invention. In the figure, the basic data structure is ISO 3.5 ″ shown in FIG.
It is the same as the optical disc standard, and has a configuration of 512 bytes of user data, 4 bytes of vendor unique data, 4 bytes of error detection code (CRC), and 80 bytes of error correction parity. SYNC and RESYNC for synchronizing data are also recorded on the actual disk at the same time, but are omitted because they are not directly related to the present invention. Also, an ID portion in which a track number and a sector number are recorded is omitted.

In FIG. 1, 600 is recorded in one sector.
The byte data is arranged in 5 rows from 0 to 4 and in 120 columns from 0 to 119.
From column data, 1 row 0 column, 2 row 0 column ... 4 row 0 column,
.. Are performed in the order of 0 rows, 1 column, 1 row, 1 column... Here, the inter-sector dispersion according to the present invention is set to four sectors. The symbol D represents user data, vendor unique data, and CRC, and the symbol P represents parity. The first half of the suffix of each symbol indicates a sector number, and the second half of the suffix indicates the order of recording / reproducing in the sector.

A description will be given by taking the data D0,0 as an example. D0,0
Constitute the same correction sequence as D1,0, D2,0, D3,
0, D0, 20, D1, 20, D2, 20, D3, 20, D0, 40, ...
D3,500, P0,0, P1,0, P2,0, P3,0, P0,20 ...
It is 120 bytes of P3,60, and has a structure of 104 bytes of data and 16 bytes of correction code.

FIG. 2 shows an example of the reproducing apparatus. In FIG. 1, 1 is an optical disk, 2 is a spindle motor, 3 is an optical pickup, 4 is a demodulation circuit, 5 is a memory circuit, 6 is a data memory address control circuit, and 7 is an error correction circuit. Actually, in addition to this, a moving mechanism and a positioning mechanism of the optical pickup, a servo circuit such as a laser beam focus control, a clock reproducing circuit for data detection, and the like are included as constituent elements. It is not shown in the figure because it does not affect the operation.

The optical disk 1 is rotated by a spindle motor 2 so as to have a constant angular velocity or a constant linear velocity. The optical pickup 3 is controlled by the above-described moving mechanism and positioning mechanism (not shown) so that a laser beam is irradiated onto the track of the optical disc 1, and is also moved to a recording surface of the optical disc 1 by a focus control circuit (not shown). Control is performed so that the laser light is focused. A pit train obtained by modulating recording data by a predetermined modulation method is recorded on a track of the optical disc 1. A pit train reproduction signal of the optical pickup 3 is demodulated by a demodulation circuit 4 according to a predetermined rule. The data string is restored to the data string before modulation.
The restored data string is stored in the data memory 5 in a predetermined number of sectors (four sectors in the case of FIG. 1). Thereafter, the data is read from the data memory 5 in the error correction circuit 7 and error correction is performed. Although the error correction algorithm is already well known and will not be described here, the data of the above-described correction code generation sequence is sequentially read and input to the error correction circuit 7.

In the example of FIG. 1 in which four correction sectors are distributed, there are 20 correction code generation sequences. Therefore, there is a method of providing a number of correction circuits corresponding to each sequence. It is also possible to provide a configuration in which the error correction operation of one or a plurality of sequences is performed at the same time, and the error correction operation of all the sequences is performed by repeating this. According to this arrangement method, the number of data and the number of parities constituting the correction code are the same as those in the ISO format shown in FIG. 6, so that the random error correction capability is the same, but the burst error correction capability is greatly improved. I do. While the burst error correction length in FIG. 6 of the conventional example is 40 bytes, the burst error correction length in FIG. 1 increases to 160 bytes.

FIG. 3 shows another second embodiment. In this example, two types of correction codes are provided for one piece of data, the first correction code being generated in a distributed manner between the sectors as in the example of FIG. 1 and the second correction code generated in the sector. ing.

The first correction code distributed between sectors is shown in FIG.
In the same manner as in the example, the data is distributed over four sectors, and one sector is similarly represented by an array of 5 rows and 120 columns. Here, the data is D, the parity by the first correction code is P, and the parity by the second correction code is Q. The meanings of the subscripts added to data and parity are the same as in FIG. Here, the correction codes related to D0,0 are D0,0, D1,0, D2,
0, D3,0, D0,20, D1,20, D2,20, D3,20, D0,40,
... 104 data of D3,500 and P0,0, P1,0, P2,
It is composed of 8 parities of 0, P3,0, P0,20... P3,35.

On the other hand, the second correction codes formed in the sector are D0,0, D0,5, D0,10, D0,15, D0,20, D0,25,
D0, 30, D0, 35, D0, 40, ..., D0, 515, 104 data, P0, 0, P0, 5, P0, 10, P0, 15, P0, 20, ... P
0,35 of the first correction code of 8 parity, Q0,0, Q0,
5, 8, Q0, 10, Q0, 15, Q0, 20,..., Q0, 35. Since both correction codes can correct up to four-byte errors, correction is performed with the second correction code and then again with the first correction code.

In the random error correction, since a plurality of data of the first correction code sequence are included in the second correction code sequence, an error occurs in five of the data included in both of them. Cannot be corrected by either correction code. Therefore, the random error correction capability is lower than the conventional system. However, regarding the burst error, even if a 16-byte burst error occurs in the second error correction sequence and the correction cannot be performed, the first error can be corrected.
These error correction sequences correct these errors, so that the burst error length in a sector is allowed up to 80 bytes. This is twice as large as the conventional method.

Next, a third embodiment will be described with reference to FIG. Also in this embodiment, regarding the error correction code,
As in the example of FIG. 3, a first error correction code distributed between sectors and a second error correction code configured in the sector are provided, but are included in the second error correction code sequence. In order to reduce the number of first code sequence data to be used, the data constituting the first error correction code sequence is shifted in the sector.

The data structure of the sector is composed of a data section of 520 bytes and a parity section of 80 bytes, as in the previous example, and has five second error correction sequences. It is represented by an array of rows 120 columns. One error correction sequence is composed of a 104-byte data part and a 16-byte parity part. Of the 16-byte parity, eight-byte parity is a first error correction code distributed between sectors described later. This is used, and is treated in the same manner as data in the generation sequence of the second error correction code completed in the sector. Therefore,
The second error correction code is regarded as an 8-parity code for 112 data. On the other hand, the first error correction code configured to be distributed among sectors is illustrated in FIG. 4 as an example where the first error correction code is distributed to 8 sectors, but is configured by 104 bytes of data and 8 bytes of parity.

In the figure, taking as an example the head data of the first sector (0 sector), that is, the data of row 0 and column 0, the generation sequence of the first error correction code distributed between sectors including this data 11 is data in row 0 and column 0 of the second sector (1 sector), 3rd sector (2 sectors)
0 row 0 column data: 8th sector (7 sectors)
0 row 0 column data, 1st sector (0 sector) 1
Data in row 8 column, row 8 in second sector (1 sector)
Column data: 1 row 8 of the 8th sector (7 sectors)
Column data, data of 2 rows and 16 columns of the first sector (0 sector),... Are performed while shifting one row in the sector. When the data reaches four rows, the process returns to zero row. By repeating this, data up to 2 rows and 96 columns is used, and the 8 parities added thereto are arranged in 3 rows and 104 columns of each sector. The other data forms an error correction code sequence according to the same rule, and a total of 40 sequences are generated.

On the other hand, as the error correction code generation sequence 12 completed within a sector, five sequences are generated for each row for each sector, and the added parity is arranged from 112 columns to 119 columns. The data and parity in one series of the error correction code dispersed among the sectors described above are
The number of data contained in the same sector in the sector is 14, and the number of data contained in the same row is two or three because the data is arranged by shifting one row at a time. Therefore,
When the data commonly included in the two types of error correction code sequences are simultaneously erroneous, the two sequences are not simultaneously uncorrectable, and the random error correction capability can be improved. Regarding the burst error correction capability, 1
Even if 64 bytes of data are continuously erroneous, correction can be made with error correction codes distributed between sectors.

As described above, the error correction capability of both random and burst can be enhanced by using two systems of error correction codes. However, the error correction capability can be further enhanced by performing repetitive correction. That is, data that could not be corrected by the second error correction code in the sector and error correction by the first error correction code between the sectors is corrected again by the second error correction code in the sector. There are error patterns that can be corrected. By repeating this further, correctable data increases.

On the other hand, when the error occurrence probability is low, only the correction by the second error correction code in the sector is normally performed, and only when an uncorrectable state occurs, the inter-sector correction is performed. Error correction using the first error correction code may be performed.

Next, a recording method will be described. FIG. 5 shows a block diagram of the recording circuit. Here, as in FIG. 2, portions not directly related to the present invention are omitted. The same parts as those in FIG. 2 are denoted by the same reference numerals. Data sent from a higher-level device (not shown) is stored in the memory circuit 5, and when data of a predetermined number of sectors for dispersing the error correction code is accumulated, the error correction code generation circuit 8 generates an error correction code.

In the example shown in FIG. 1, data at a predetermined position is read out by the memory address control circuit and input to the error correction code generation circuit 8. When a predetermined number of data is input and a parity is generated, the parity is read from the error correction code generation circuit 8 and stored in a predetermined position of the memory circuit 5. This operation is performed for all code sequences, and when all the parities are generated, the drive device is set to a recording state, and the data and the parities of all the sectors stored in the memory circuit are subjected to predetermined modulation by the modulation circuit 9 to perform optical modulation. Is modulated and recorded on the optical disc 1. The data to be recorded sent from the host device is one of the operations described above.
If recording cannot be performed in batches, recording is performed by repeating this.

If the data to be recorded is less than the number of recordable data for one operation described above, ie, the number of sectors to be dispersed, the missing data is filled using pseudo data, for example, fixed data, and recording is performed. When two types of error correction codes within a sector and between sectors are used as in the embodiments described with reference to FIGS. 3 and 4, after storing a predetermined number of sectors of data in a memory circuit, An error correction code dispersed in the middle is generated, and then an error correction code completed in the sector is generated and recorded.

In the recording method described above, since the recording according to the present invention can be performed for each set of data instructed by the higher-level device to record, the present invention can be applied to a write-once medium or a rewritable medium. Further, at the time of reproduction, unnecessary data need not be read only for correction, so that the data read time can be reduced. Further, by managing the order of the sector positions on the medium on which writing is performed, the sectors to be actually recorded do not need to be continuous on the medium, and the medium can be effectively used.

FIG. 5 shows a recording circuit based on a laser power modulation system. However, in a magneto-optical disk drive, a constant recording laser beam is applied to change the magnetic field polarity of a magnetic head according to recording data. Alternatively, the present invention is similarly realized in a method of modulating both the laser power and the magnetic field.

Next, as another recording method, when all the data to be recorded on the medium is previously known, as in the case of producing a read-only medium, regardless of the data collection unit, The present invention can be applied to each successive sector for recording.

In this recording method, it is desirable to set the number of sectors for dispersing the error correction code to the number of sectors that can be recorded in one track of the medium or the number of sectors obtained by equally dividing the number of sectors by an integer value. By making such settings, the head and block of the sector to be corrected during reproduction can be easily recognized, and the correction operation can be completed in one track. The tracks and sectors at this time need not necessarily be physical tracks and sectors defined by one round of the medium.

In a medium in which the rotation speed of the medium is constant and the recording / reproducing data cycle is constant, the number of sectors in the physical track is constant from the inner circumference to the outer circumference. In a medium in which the medium is divided into a plurality of zones and the number of revolutions and the recording / reproducing data cycle are changed for each zone, the number of sectors in the physical track varies depending on the medium diameter or the zone. It is often defined as a track and does not use a physical track. Therefore, in this case, it is desirable to set the number of sectors in which the error correction code is distributed and arranged to the number of sectors constituting the logical track or the number of sectors obtained by equally dividing the number of sectors by an integer value. The recording device in this case can also be realized by the configuration shown in FIG. 5, but as another realizing means, a storage device capable of storing all data and parity to be recorded is provided, and a parity for all data is generated in advance and stored in the storage device. However, it can be read out and recorded continuously. The generation of the error correction code at this time can also be performed by software operation by a computer.

In any of the embodiments described above, the error correction code can be realized by the same error correction code having the conventional sector configuration shown in FIG. Can be used. Therefore, it is easy to share the recording apparatus, the reproducing apparatus, and the recording / reproducing apparatus with the conventional format write-once or rewritable recording medium and read-only medium to which the present invention is not applied.

Although the present invention has been described based on the embodiments, the sector configuration, the configuration of the error correction code, the number of sectors to be dispersed, and the like mentioned above are all examples, and the present invention is not limited to these. However, the present invention is also realized in other sector configurations, error correction codes, and numerical values.

[0039]

As described above, according to the present invention,
Burst error correction capability can be increased, and the reliability of recorded data can be increased. In addition, since the present invention can be applied to a recording file unit and can be easily recorded on a drive device, it can be used not only for a read-only disc but also for a write-once disc and a rewritable disc, thereby improving the reliability of recorded data. Can be.

[Brief description of the drawings]

FIG. 1 shows a first embodiment according to the present invention.

FIG. 2 shows a configuration example of a reproducing apparatus according to the present invention.

FIG. 3 shows a second embodiment according to the present invention.

FIG. 4 shows a third embodiment according to the present invention.

FIG. 5 is a configuration example of a recording apparatus according to the present invention.

FIG. 6 shows a conventional sector configuration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Spindle motor, 3 ... Optical pickup, 4 ... Demodulation circuit, 5 ... Memory circuit, 6 ... Address control circuit, 7 ... Error correction circuit, 8 ... Error correction code generation circuit, 9 ... Modulation circuit, 10 ... Sector, 11 ... Generation sequence of first error correction code, 12 ... Generation sequence of second error correction code

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Claims (2)

[Claims] 1. An information reproducing method for reproducing information from an information recording medium on which a plurality of sectors as information recording units are recorded, wherein the information recording medium comprises an error correction block including a plurality of the sectors, An error correction code is generated for a set of data collected by a predetermined number from each of a plurality of sectors included in the error correction block, and the error correction code is generated by each sector including the data collected by the predetermined number. The data of a plurality of sectors, which are recorded in a distributed manner and are included in the error correction block reproduced from the information recording medium, are held in storage means, and the data in the error correction block read from the storage means and An information reproducing method, wherein error correction is performed for each error correction block using an error correction code distributed to a plurality of sectors. 2. An information reproducing apparatus for reproducing information from an information recording medium on which a plurality of sectors as information recording units are recorded, wherein the information recording medium comprises an error correction block including a plurality of the sectors, An error correction code is generated for a set of data collected by a predetermined number from each of a plurality of sectors included in the error correction block, and the error correction code is generated by each sector including the data collected by the predetermined number. Storage means for holding, for each error correction block, data of a plurality of sectors which are recorded in a distributed manner and are included in the error correction block reproduced from the information recording medium, and the error correction read from the storage means Error correction means for performing error correction for each error correction block using data in the block and the error correction codes distributed to the plurality of sectors. Information reproducing apparatus according to claim.