JP3384402B2 - Information reproducing method and information reproducing apparatus - Google Patents

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 an error in information in an apparatus for recording and reproducing information on a disk-shaped recording medium, and particularly to an information reproducing method and an information reproducing apparatus therefor. To do.

[0002]

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

[0003]

However, the optical disk has a higher error rate than the conventional magnetic disk and is premised on the use of an error correction code. The form of error generation in an optical disc is divided into random error and burst error. Random errors are due to noise and the like, and errors occur in bit units. Burst error is caused by defects, dust, or scratches on the disc, and consecutive bits are erroneous.

FIG. 6 shows the structure of a sector in an ISO standard 3.5 "optical disk. The sector 10 has 512 bytes of user data, 4 bytes of vendor unique data, 4 bytes of error detection code (CRC) by cyclic code, and read. The error correction code (ECC) parity of the Solomon code is composed of 80 bytes.The error correction code generation sequence divides 520 bytes in total of user data, vendor unique data, and CRC into 5 bytes every 104 bytes. A 16-byte ECC parity is generated, and the entire sector constitutes 5 error correction sequences (5 interleaves). It can correct up to 8 bytes of error, and can correct 40 bytes of error in the whole sector. , For the burst error, in one sector, it has a correction capability of the continuous 40 byte.

However, in an actual optical disc, a random error and a burst error occur at the same time, and a burst error within the correction range occurs in a fixed manner. When the random error occurs in the correction range, the number of random errors is reduced to the correction range. Even inside, the result is uncorrectable.

Therefore, it is necessary to eliminate fixed burst errors as much as possible during data recording. Therefore, in the rewritable disc device, a method is adopted in which, when the number of errors in reproducing information immediately after recording exceeds a predetermined number even if it is within the range of error correction capability, the data is rewritten to another place.

However, in a ROM disk in which information is recorded in pre-pits at the time of manufacturing the disk, such rewriting cannot be performed. Therefore, in the ISO 3.5 "standard, one parity sector is provided for every 25 sectors and each sector has the same position. Exclusive-OR (EO) certain data byte by byte
R) is performed and recorded in the parity sector. However, in this parity method, since a sector for parity is required separately from that for data, the recording efficiency is lowered, and since only one byte error can be corrected by one correction sequence, a burst error and a random error are combined. When it occurs, it becomes uncorrectable, and higher error correction capability is required.

[0008]

In order to solve the above problems, in the present invention, error correction code sequences are arranged in a distributed manner among sectors which are blocks of information recording. The reproducing apparatus has a storage unit for storing data of a plurality of distributed sectors and a correction unit.

As another means, there are provided two systems, that is, a sequence in which error correction code sequences are distributed and arranged in a sector, and a sequence in which error correction code sequences are distributed and arranged between sectors. In the reproducing apparatus, a storage unit for storing data of a plurality of sectors, a first error correction unit for correcting data distributed in the plurality of sectors, and a second error correction unit for correcting data distributed in the sectors.
Error correction means. Alternatively, it has one error correction circuit for sequentially correcting the data distributed in the sector and the data distributed in the sector.

[0010]

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

In addition to this, an error correction code is generated from 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 0 sector to n sector is held in the storage unit, the data in each sector and the error correction code are read from the storage unit, and the correction in the sector is performed.

After performing the correction operation for all the sectors, the data of the data series distributed between the sectors and the error correction code are
0 sector, 1 sector, 2 sector ... N sector, 0 sector ... By performing double error correction on 1-byte data, the correction capability is enhanced. Or 0
The error correction in the sector is performed while storing the data from the sector to the n-sector in the storage means, and when an uncorrectable error occurs, the error correction between the sectors is performed.

[0013]

EXAMPLES The present invention will be described below with reference to examples. Figure 1
A first example of the sector structure according to the present invention is shown in FIG. In the figure, the basic data structure is ISO3.5 "shown in FIG.
It is the same as the optical disc standard, and has 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 an actual disc at the same time, but they are omitted because they are not directly related to the present invention. Similarly, the ID portion in which the track number and sector number are recorded is also omitted.

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

The data D0,0 will be described as an example. D0,0
The same correction sequence as that of 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 104 bytes of data and 16 bytes of correction code.

FIG. 2 shows an example of the reproducing apparatus. In the figure, 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 an address control circuit of a data memory, and 7 is an error correction circuit. In addition to this, in addition to this, a moving mechanism and a positioning mechanism of the optical pickup, a servo circuit for focus control of laser light, a clock reproducing circuit for data detection, and the like are constituent elements. It is not shown in the figure because it has nothing to do with the action.

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 moving mechanism and the positioning mechanism (not shown) so that the laser beam is irradiated onto the track of the optical disc 1, and the recording surface of the optical disc 1 is also controlled by a focus control circuit (not shown). The laser light is controlled to be in focus. On the track of the optical disc 1, a pit train obtained by modulating recorded data by a predetermined modulation method is recorded, and a pit train reproduction signal of the optical pickup 3 is demodulated by a demodulation circuit 4 according to a predetermined law, It is restored to the data string before modulation.
The restored data string is stored in the data memory 5 by a predetermined number of sectors (4 sectors in the case of FIG. 1). Then, the error correction circuit 7 reads the data from the data memory 5 and corrects the error. Although an error correction algorithm is already well known, it will not be described here, but the data of the above-mentioned correction code generation sequence is sequentially read and input to the error correction circuit 7.

In the example of FIG. 1 in which the correction code generation sequence is distributed to 4 sectors, there are 20 correction code generation sequences, so there may be a method of providing a correction circuit of the number corresponding to each sequence, but one or more correction circuits are provided. There is provided a configuration in which the error correction operation for one series or a plurality of series is performed at the same time, and the error correction operation for all the series is performed by repeating this. According to this arrangement method, since the number of data forming the correction code and the number of parities are the same as in the ISO format shown in FIG. 6, the random error correction capability is the same, but the burst error correction capability is greatly improved. To do. While the burst error correction length according to the conventional example shown in FIG. 6 is 40 bytes, the burst error correction length shown in FIG. 1 is increased to 160 bytes.

FIG. 3 shows another second embodiment. In this example, for one data, two systems of correction codes, that is, a first correction code generated by being dispersed among sectors similar to the example of FIG. 1 and a second correction code generated in a sector are provided. ing.

The first correction code distributed between the sectors is shown in FIG.
As in the above 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 the 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,
0, P3,0, P0,20 ... P3,35 are composed of 8 parities.

On the other hand, the second correction code formed in the sector is D0,0, D0,5, D0,10, D0,15, D0,20, D0,25,
104 data of D0,30, D0,35, D0,40, ... D0,515, P0,0, P0,5, P0,10, P0,15, P0,20 ... P
8 parity of the first correction code of 0,35, Q0,0, Q0,
5, Q0,10, Q0,15, Q0,20 ... Q0,35. Since both the correction codes can correct an error of 4 bytes respectively, after the correction is performed by the second correction code, the correction is performed again by the first correction code.

In the random error correction, since the second correction code series contains a plurality of data of the first correction code series, an error occurs in 5 pieces of data included in both of them. With either of the correction codes, the correction cannot be performed. Therefore, the random error correction capability is lower than that of the conventional method. However, regarding the burst error, even if a 16-byte burst error occurs in the second error correction sequence and correction cannot be performed, the first error
Since these errors are corrected by the error correction sequence of, the burst error length within the sector is allowed up to 80 bytes. This is twice as much as the conventional method.

Next, a third embodiment will be described with reference to FIG. Also in this embodiment, regarding the error correction code,
Similar to the example of FIG. 3, the first error correction code distributed between the sectors and the second error correction code formed in the sector are provided, but they are included in the second error correction code sequence. In order to reduce the number of first code sequence data to be generated, the data forming the first error correction code sequence is arranged so as to be offset in the sector.

The data structure of the sector is composed of a data part of 520 bytes and a parity part of 80 bytes, as in the above examples, and has a second error correction series of 5 series, and one sector consists of 5 parts. It is represented by an array of 120 columns. One error correction sequence is composed of a 104-byte data section and a 16-byte parity section. Of the 16-byte parity, 8-byte parity is the first error-correction code distributed among the sectors described later. It is used and is treated in the same way as data in the generation sequence of the second error correction code which is completed within the sector. Therefore,
The second error correction code is regarded as a code having 112 parity and 8 parity. On the other hand, the first error correction code formed by being distributed among the sectors is shown as an example of being distributed by 8 sectors in FIG. 4, but is made up of 104 bytes of data and 8 bytes of parity.

In the figure, taking the first data of the first sector (0 sector), that is, the data of 0th row and 0th column as an example, the generation sequence of the first error correction code dispersed among the sectors including this data. 11 is the data in the 0th row and 0th column of the second sector (1 sector), and the 3rd sector (2 sectors)
0th row and 0th column data ... 8th sector (7 sectors)
0 row, 0 column data, 1st sector (0 sector) 1
Row 8 column data, 2nd sector (1 sector) 1 row 8
Column data: 1 row 8 of the 8th sector (7 sectors)
Column data, 1st sector (0 sector), 2 rows and 16 columns of data, etc. are sequentially shifted in the sector, and when the number of rows reaches 4, it returns to 0 rows. By repeating this, data up to 2 rows and 96 columns is used, and 8 parities added thereto are arranged in 3 rows and 104 columns of each sector. The error correction code sequence is configured by the same rule for other data, and a total of 40 sequences are generated.

On the other hand, the error correction code generation sequence 12 that is completed in each sector has five sequences generated for each row for each sector, and the added parity is arranged in columns 112 to 119. The data and parity in one sequence of error correction codes distributed among the above-mentioned sectors are distributed in 8
The number of sectors included in the same sector is 14, and the numbers of data included in the same row are 2 or 3 because they are arranged one row at a time. Therefore,
Random error correction capability can be improved without causing both sequences to become uncorrectable at the same time due to simultaneous error in the data commonly contained in the two types of error correction code sequences. Burst error correction capability is 1 within a sector
Even if 64 bytes of data are continuously erroneous, they can be corrected with error correction codes distributed among the sectors.

As described above, the error correction capability of both random and burst can be enhanced by using the error correction code of two systems, but it is also possible to further enhance the correction capability by performing repeated correction. That is, the data that could not be corrected by the error correction by the second error correction code in the sector and the error correction by the first error correction code between 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, the correctable data increases.

On the contrary, when the error occurrence probability is low, only the correction by the second error correction code in the sector is always performed, and only when the uncorrectable state occurs, the inter-sector correction is performed. It is also possible to perform error correction using the first error correction code.

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

In the example of FIG. 1, the memory address control circuit reads data at a predetermined position and inputs it to the error correction code generation circuit 8. When a predetermined number of data are input and a parity is generated, this is read from the error correction code generation circuit 8 and stored in a predetermined position of the memory circuit 5. When this operation is performed for all code sequences and all the parities have been generated, the drive device is set to the recording state and the modulation circuit 9 performs predetermined modulation on the data and parities of all the sectors stored in the memory circuit, and the optical pickup 3 The laser light power 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 it is not possible to record in batches, record by repeating this.

When the data to be recorded is less than one operation described above, that is, the recordable data of the dispersed sectors, the insufficient data is filled with pseudo data, for example, fixed data, and recording is performed. When two types of error correction codes are used in and between sectors as in the embodiment described with reference to FIGS. 3 and 4, after storing a predetermined number of sectors of data in the memory circuit, the sectors are read as described above. The error correction codes dispersed in between are generated, and then the error correction codes completed within the sector are 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 to be recorded by the host device, the present invention can be applied to the write-once medium or the rewritable medium for recording. Further, since it is not necessary to read unnecessary sectors only for correction during reproduction, the data read time can be shortened. Furthermore, by managing the sector positions on the medium for writing so that the order is clear, the sectors to be actually recorded do not have to be consecutive on the medium and the medium can be effectively used.

Although the recording circuit using the laser power modulation method is shown in FIG. 5, in the magneto-optical disk device, a magnetic field modulation method is used in which a constant recording laser beam is irradiated to change the magnetic field polarity of the magnetic head according to the recording data. The same is also realized in the 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 are known in advance, as in the case of producing a read-only medium, regardless of the unit of data set, the medium is recorded on the medium. 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 distributing 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 this number of sectors by an integer value. With such a setting, the head and block of the sector to be corrected can be easily recognized at the time of reproduction, and the correction operation can be completed in one track. Further, the tracks and sectors at this time do not necessarily have to be physical tracks and sectors defined by one round of the medium.

In a medium in which the number of rotations 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, but the recording / reproducing is performed at a constant linear velocity. In a medium in which the medium is divided into a plurality of zones and the number of rotations and the recording / reproducing data period are changed for each zone, the number of sectors in a physical track varies depending on the medium diameter or the zone, and therefore a fixed set of sectors is logically set. It is often defined as a track and a physical track is not used. Therefore, in this case, it is desirable to set the number of sectors in which error correction codes are dispersedly arranged to the number of sectors forming 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 to be recorded and parity is provided, and parity for all data is generated in advance and stored in the storage device. However, it can also be read and recorded continuously. The error correction code generation at this time can also be performed by software calculation by a computer.

Further, in any of the embodiments described so far, the error correction code can be realized with the same error correction code as the conventional sector structure shown in FIG. 6, and the code generation circuit and the correction circuit are conventionally used. It is also possible to use the code generation circuit and the correction circuit. Therefore, it is possible to easily share the write-once or rewritable recording medium and the read-only medium of the conventional format to which the present invention is not applied, the recording device, the reproducing device and the recording / reproducing device.

The present invention has been described above based on the embodiments, but the sector configuration, the error correction code configuration, the number of sectors to be dispersed, and the like, which are given as examples, are all examples, and the present invention is limited to these. However, it is also realized by other sector configurations, error correction codes, and numerical values.

[0039]

As described above, according to the present invention,
The burst error correction capability can be increased, and the reliability of recorded data can be improved. Further, since the present invention can be applied to each recording file and recording can be easily performed on the drive device, it can be used not only on a read-only disc but also on a write-once disc and a rewritable disc, thereby improving the reliability of recorded data. You can

[Brief description of drawings]

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

FIG. 2 is a structural example of a reproducing apparatus according to the present invention.

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

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

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

FIG. 6 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

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G11B 20/18 G11B 20/18 572F (56) References JP-A-5-89609 (JP, A) JP-A-60-261076 ( JP, A-JP 7-230674 (JP, A) JP 63-148471 (JP, A) JP 63-251968 (JP, A) JP 3-266264 (JP, A) JP Sho 62-205582 (JP, A) JP 4-67471 (JP, A) JP 6-236632 (JP, A) JP 4-105271 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G11B 20/10 G11B 20/18

Claims (2)

(57) [Claims] 1. An information reproducing method for reproducing information from an information recording medium in which a plurality of sectors as information recording units are recorded, wherein the information recording medium comprises an error correction block composed of a plurality of the sectors, Data at the same position between sectors from a plurality of sectors included in the error correction block
An error correction code is generated for a set of data collected by a predetermined number, and the error correction code is dispersedly recorded in each sector containing the data collected by the predetermined number. Holding data of a plurality of sectors included in the reproduced error correction block in a storage means,
An information reproducing method characterized by performing error correction for each error correction block using the data in the error correction block read from the storage means and the error correction code distributed in the plurality of sectors. 2. An information reproducing apparatus for reproducing information from an information recording medium in which a plurality of sectors as information recording units are recorded, wherein the information recording medium comprises an error correction block with the plurality of sectors. Data at the same position between sectors from a plurality of sectors included in the error correction block
An error correction code is generated for a set of data collected by a predetermined number, and the error correction code is dispersedly recorded in each sector containing the data collected by the predetermined number. Storage means for holding, for each error correction block, data of a plurality of sectors included in the reproduced error correction block, data in the error correction block read from the storage means, and data distributed to the plurality of sectors. An information reproducing apparatus comprising: an error correcting unit that performs error correction for each of the error correction blocks using an error correction code.