Error detection/correction and fault detection/recovery – Pulse or data error handling – Replacement of memory spare location – portion – or segment
Reexamination Certificate
2002-10-09
2004-02-24
Psitos, Aristotelis M. (Department: 2653)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Replacement of memory spare location, portion, or segment
C714S002000, C369S053170, C360S053000
Reexamination Certificate
active
06697977
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a disc recording apparatus for recording data onto e.g. a magneto-optical disc while detecting defective sectors. The present invention also relates to a method for the apparatus to replace a sector on the recording disc. The present invention further relates to the recording disc.
BACKGROUND ART
Due to increased capacity, magneto-optical discs in recent years have an increasingly narrow track pitch. This has increased probability of error occurrence when writing data on the magneto-optical disc. At the time of data writing error, a retry is made as many times as predetermined. If the data writing is not successful within the predetermined number of retries, a decision is made finally that the writing has failed. A recent tendency is that the number of retries (retry count) is also increasing. This means that a long time is spent in vain for retries, resulting in prolonged access time. Consequently, there is a need for a technique to reduce the access time.
As shown in
FIG. 11
, a conventional recorder/player A
10
formats a magneto-optical disc B
10
in response to a command from a host personal computer C
10
. During the formatting, a CPU
110
of the recorder/player A
10
writes initializing data onto each sector that provides a unit recording-area on the magneto-optical disc B
10
.
During this formatting, when there is a failure in writing the initializing data in one of the sectors, the CPU
110
makes a retry until the predetermined number of retries is reached. If the writing is not successful within the predetermined number of retries, the CPU
110
stores the address of the failed sector in a RAM
120
in the form of PDL (Primary Defect List). At the end of the formatting, the PDL is recorded as part of medium management information B
11
on the magneto-optical disc B
10
.
On the other hand, the sectors onto which the initializing data was successfully recorded within the predetermined number of retries do not have their addresses listed in the PDL, and are allowed for use as flawless sectors. Such a formatting procedure is executed to all the sectors which are to be formatted.
Now, description will be given more about the PDL.
FIG. 12
shows a zone without any defective sectors. Now, compare
FIG. 12
to FIG.
13
: When a defective sector is found in a data zone while formatting a magneto-optical disc B
10
, the defective sector is skipped, and the initializing data is written onto the next sector. In this way, the data zone including the defective sector is extended into a spare zone in order to provide a predetermined number of flawless sectors by using a spare sector(s) available in the spare zone. The address of the defective sector is stored in the RAM
120
. Such a defect, i.e. a defect in which address can be assigned while skipping a defective sector, is called primary defect. A set of addresses of the defective sectors that fall into the category of the primary defect is called PDL.
Now the formatting is over. When actual data is written onto this magneto-optical disc B
10
, the CPU
110
of the recorder/player A
10
writes the actual data onto a sector specified by an address in response to a “write” command from the personal computer C
10
.
When the writing of the actual data is not successful, the CPU
110
makes a retry until a predetermined number of retries is reached. If the writing of the actual data is still not successful within the predetermined number of retries, the CPU
110
recognizes this sector that does not accept the actual data, as a defective sector, and then performs a replacement procedure in which the actual data is written onto another sector.
Specifically, during the replacement procedure, the CPU
110
searches a spare zone which immediately follows the data zone including the defective sector, selects an unused spare sector closest to the defective sector, as a replacement sector, and writes the actual data onto the replacement sector.
If the replacement sector does not allow writing, the CPU
110
makes a retry, seeking for another replacement sector. If the writing of the actual data is not successful within a predetermined number of retries, then another cycle of the replacement procedure is performed.
Such a replacement procedure performed within the spare zone is called re-replacement procedure, in which the cycle of seeking a replacement spare is repeated until the actual data is successfully written so long as a predetermined number of retries is not yet been reached.
When the actual data has been successfully written within the predetermined number of retries, the CPU
110
records addresses of the defective sectors that did not allow writing of the actual data, in the form of SDL (Secondary Defect List) in the medium management information B
11
of the magneto-optical disc B
10
, and then reports to the personal computer C
10
the successful completion. When the actual data has not been successfully written within the predetermined number of retries, the CPU
110
reports a disc error to the personal computer C
10
.
Now, description will be given more about the SDL.
FIG. 12
shows a zone without any defective sectors. Now, compare
FIG. 12
to FIG.
14
: When a defective sector is found while writing actual data, the actual data is written in a sector in the spare zone, in place of the defective sector. Then, the address of the defective sector which was replaced and the address of the spare sector which replaced are recorded onto the medium management information B
11
. Such a defect, i.e. a defect in which a replacing spare sector can be specified by address conversion, is called secondary defect. A set of addresses of the defective sectors that fall into the category of the secondary defect is called SDL.
With the above, the CPU
110
performs the replacement procedure when a defective sector is found while writing actual data based on an address specified by the host personal computer C
10
. However, there is no guarantee that the writing will be successfully completed in the replacing sector. Sometimes, the replacing sector has a higher error probability than the replaced sector which was found defective. Thus, there have been cases in which the replacement procedure was repeated in vain to such a replacing sector, before the re-replacement procedure was finally inaugurated.
As understood, execution of the re-replacement procedure means that the replacement procedure is repeated twice or even more times in order to write actual data onto one sector, that a huge number of retries must be made for the writing of actual data, and as a result, that a long time is needed for the writing of actual data including the time spent for the replacement procedures. This creates a delay in response to the “write” command from the personal computer C
10
, leading to a “timeout” error in the personal computer C
10
.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to provide a disc recording apparatus, a method for replacing sector on a recording disc and the recording disc, capable of reducing the access time without spending as much time when data writing is not successful.
A first aspect of the present invention provides a disc recording apparatus for writing data onto a sector providing a recording area on a recording disc. Upon failure in the writing, the apparatus performs a retry until a predetermined number of retries is reached, treats the sector as a defective sector upon failure in the last retry of the predetermined number of retries, and writes the data onto another sector. The apparatus comprises: a recording section recording onto the recording disc a retry count as retry count information for each of recovered sectors recovered from the failure through success in the writing of data during the retry; and a sector replacing section selecting a replacement sector for the defective sector detected upon the failure in the writing onto the recording disc containing the retry count information recorded by the recording section. The replaceme
Greer Burns & Crain Ltd.
Psitos Aristotelis M.
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