Data recording/reproducing method, data reproducing apparatus an

Details Data recording/reproducing method, data reproducing apparatus an Data recording/reproducing method, data reproducing apparatus an

1996-05-08

1998-07-14

Baker, Stephen M.

Excavating

371 377, 371 4014, G11B 2018

Patent

active

057815658

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a data recording/reproducing method, a data reproducing apparatus and a recording medium for use with an optical disk drive or the like, for example.


BACKGROUND ART

A magneto-optical disk, a phase-change type optical disk, a write-once disk and a read-only optical disk are proposed as optical disks. These optical disks are roughly classified as writable disk and read-only disk.
If a defective sector is detected from a magneto-optical disk serving as a rewritable disk by a disk-certify executed when the magneto-optical disk is manufactured, then a sector following the defective sector is used as a replacement sector, which information is recorded on a predetermined area of the magneto-optical disk. Upon reproduction, the replacement sector of the defective sector is used. If a defective sector occurs after the magneto-optical disk has been shipped, then a replacement sector of the defective sector is set in a region exclusively used by the replacement sector of the defective sector. Data that should be recorded on the defective sector is recorded on the replacement sector, which information is recorded on a predetermined area of the magneto-optical disk.
Data cannot be recorded on the read-only optical disk by an optical disk drive. As is well known, when the read-only optical disk is manufactured, data is recorded on the read-only optical disk. After the read-only optical disk has been shipped, data that had been recorded when the read-only optical disk was manufactured, can be read out.
If data is recorded on the magneto-optical disk by the optical disk drive, or data is recorded on the read-only optical disk when the read-only optical disk is manufactured, parity-check codes for error-correction and parity-check codes such as error-checking CRC (cyclic redundancy check) codes are added to data. Therefore, upon reproduction, regardless of the magneto-optical disk and the read-only optical disk, reproduced data is error-checked and error-corrected by the parity-check code.
A known parity-check code forms a Reed-Solomon code. The Reed-Solomon code is n-symbol code where a parity-check code is added to k-symbol data where one symbol is formed of 8 bits and the data is formed of k symbols. An error-correcting capability of an error-correcting code is expressed by minimum distance.
When one symbol is one bit, for example, n symbols are expressed by n bits so that binary data sequences that the n symbols can take are expressed by 2.sup.n. On the other hand, since 2.sup.k data except the parity-check codes are required, 2.sup.k data sequences are taken out from the 2.sup.n data sequences. When arbitrary two data sequences have different bits of d bits therebetween, where d means a distance, then. Then, a minimum value which results from similarly calculating distances with respect to all 2.sup.k data sequences is referred to as a minimum distance. This "minimum distance" will hereinafter be referred to as "distance" for the sake of simplicity.
In general, a distance d of the error-correcting code for error-correcting t1 errors should satisfy the following equation (1):
When the distance d is 17, for example, t1 becomes 8. That is, errors up to 8 symbols can be corrected.
The above-mentioned parity-check code has not only the error-correcting capability but also error-detecting capability. If the number of errors that can be detected by the error-detecting capability is taken as t2, then the error-detection number t2 is expressed by the following equation (2):
If the distance d, for example, is 17, then the error-correction number t1 and the error-detection number t2 can be expressed by the following table 1.


TABLE 1 ______________________________________ symbols to be corrected t1 t2 ______________________________________ 0 symbol t1 = 0 t2 = 16 1 symbol t1 = 1 t2 = 14 2 symbols t1 = 2 t2 = 12 3 symbols t1 = 3 t2 = 10 4 symbols t1 = 4 t2 = 8 5 symbols t1 = 5 t2 = 6 6 symbols t1 = 6 t2 = 4 7 symbols t1 = 7 t2 = 2 8 symbols t1 = 8 t2 =

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