Defect area management method of optical recording medium

Details Defect area management method of optical recording medium Defect area management method of optical recording medium

1999-07-01

2003-02-25

Beausoleil, Robert (Department: 2184)

Error detection/correction and fault detection/recovery

Data processing system error or fault handling

Reliability and availability

C714S723000, C714S769000, C369S047140, C369S053150, C369S053160, C369S053170, C369S059250, C369S275300

Reexamination Certificate

active

06526522

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rewritable optical recording media and more particularly to a defect area management method of an optical recording medium.
2. Discussion of Related Art
A rewritable optical disc generally includes a Rewritable Compact Disc (CD-RW) and a Rewritable Digital Versatile Disc (DVD-RW, DVD-RAM and DVD+RW).
The rewritable optical disc performs repeated operations for recording/playback of information thereon. However, by the repeated operations, a mixture ratio of the mixture forming a recording layer for recording the information on the optical disc is changed from an initial mixture ratio thereof. Thus, the inherent characteristic of the optical disc is not maintained, thereby generating errors during recording/playback of information. This is commonly known as degradation.
The area where degradation occurs is designated as a defect area which appears upon the implementation of formatting, recording and playback commands of the optical disc. The defect area of rewritable optical discs may also be generated due to scratches on the surface, particles such as dust, and errors during manufacturing. Therefore, to prevent data from being recorded on or playback from defect areas of the optical disc, an effective management system for the defect area is necessary.
As shown in
FIG. 1
, a management system for defect areas on an optical disc is achieved by allocating a defect management area (DMA) in a lead-in area and a lead-out area of the optical disc. Also, a data area is managed in groups, each having a user area for actual recording of data and a spare area for use in case of defects in the user area.
Typically, one disc (e.g. DVD-RAM) has four DMAs, two in the lead-in area and two in the lead-out area. Since managing defect area is important, the same data are held in all four DMAs for data protection. Each DMA includes two blocks and of 32 sectors, wherein one block consists of 16 sectors. The first block (DDS/PDL block) of each DMA includes a disc definition structure (DDS) and a primary defect list (PDL), and the second block (SDL block) includes a secondary defect list (SDL)
More specifically, the PDL represents a primary defect data storage area, and the SDL represents a secondary defect data storage area. The PDL stores entries of all defective sectors generated during manufacture and identified during formatting such as initialization or re-initialization. Each entry, as shown in
FIG. 2A
, includes a sector number corresponding to a defective sector and an entry type. The sector number is listed in the carry order, and the entry type is listed by the origin of the defective sector.
For example, the entry type is divided into a P-list, a G
1
-list and a G
2
-list, as defined by the disc manufacturer. More particularly, the defective sectors generated during the manufacture of the disc are stored in the P-list. The defective sectors found by a certification process during a formatting of a disc are in the G
1
-list, and the defective sectors converted from the SDL without any certification process are in the G
2
-list.
On the other hand, the SDL is arranged in block units and holds entries of either defective areas which may be generated after initialization or defective areas which cannot be entered in the PDL during initialization. Each entry of the SDL as shown in
FIG. 2B
includes an area storing the sector number of a first sector of the block having a defective sector, and an area holding the sector number of a first sector of a replacement block. Additionally, 1 bit is assigned for the FRM. A FRM bit value of ‘
0
b
’ indicates that a replacement block is assigned and the block is in a functional state. Contrarily, a FRM value of ‘
1
b
’ indicates that either a replacement block is not assigned or a defect on the replacement block exists.
The initializing method of a disc is divided into an initialization formatting and a re-initialization formatting. The re-initialization formatting method is further classified into a full formatting similar to the initialization formatting, a partial certification for a partial initialization, and a conversion of SDL to G
2
-list by which the SDL is transferred to the G
2
-list of the PDL without the certification process in order to reduce the formatting time. The P-list remains unchanged after the completion of formatting but defective blocks of the SDL are stored as defective sectors in the G
2
-list. Thus, the G
2
-list may include defective sectors as well as non-defective sectors.
As shown in
FIG. 3A
, in the partial certification, the sectors on the P-list and G
1
-list prior to the formatting remain on the P-list and the G
1
-list after the completion of formatting. However, the defective blocks on the old G
2
-list and old SDL undergo a certification process. Namely, the entries of the G
2
list and the SDL are erased, and defective sectors found during the certification process are listed in the G
1
-list.
This is because non-defective sectors are also entered as part of the defective block on the G
2
-list and the SDL. At this time, if an overflow occurs on the G
1
-list, the remaining entries are listed on the new SDL and null data is inserted into the G
2
-list. An overflow may occur because as the PDL is comprised of 15 fixed sectors in the DMA, the number of entries which is registered in the PDL is restricted.
The conversion format of the SDL to the G
2
-list without certification is shown in FIG.
3
B. The sectors in the P-list, G
1
-list and G
2
-list prior to the formatting remain without change in the P-list, G
1
-list and G
2
-list after the completion of the formatting. The entries on the SDL are converted into 16 PDL entries and are then listed in the G
2
-list. At this time, if an overflow occurs on the G
2
-list, the remaining entries which cannot be entered in the G
2
-list, are listed on the new SDL.
On the other hand, defective areas in the data area (i.e. defective sectors or defective blocks) are replaced with new non-defective sectors or blocks, respectively by slipping replacement or linear replacement.
The slipping replacement is utilized when a defective area or sector is listed in the PDL. As shown in
FIG. 4A
, if defective sectors m and n, corresponding to sectors in the user area, are recorded in the PDL, such defective sectors are replaced by the next available sector. By replacing the defective sectors by subsequent available sectors, data is written to a normal sector.
As a result, the user area into which data is written slips and occupies the spare area in the amount equivalent to the defective sectors. For example, if two defective sectors are recorded on the P-list or the G
1
-list of a PDL, the data is pushed back two sectors into the spare area and is then recorded.
The linear replacement is utilized when a defective area or block is recorded in the SDL. As shown in
FIG. 4B
, if defective sectors m and n, corresponding to sectors in either the user or spare area, are recorded on the SDL, such defective blocks are replaced by normal blocks in the spare area and the data to be recorded in the defective block are recorded in an assigned spare area. To achieve the replacement, a physical sector number (PSN) assigned to a defective block remains, while a logical sector number (LSN) is moved to the replacement block along with the data to be recorded. Linear replacement is effective for non real-time processing of data.
More particularly, if a replacement block recorded in the SDL has been defective, a direct pointer method is applied in the data registration of the SDL. The defective replacement block is changed into a new replacement block by the application of the direct pointer method. Thus, the entries on the SDL where the defected replacement block has been entered have the sector number of a first sector of the new replacement block.
FIGS. 5A
to
5
I show an optical disc structure as discussed above.
FIG. 5A
shows defect areas appearing on the disc and a management state for the defect are

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