Method for formatting, and managing defective area of,...

Details Method for formatting, and managing defective area of,... Method for formatting, and managing defective area of,...

1999-10-20

2002-07-09

Huber, Paul W. (Department: 2653)

Dynamic information storage or retrieval

Control of storage or retrieval operation by a control...

By medium defect indicative control signal

C369S053160

Reexamination Certificate

active

06418100

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for formatting, and managing defective areas of a rewritable optical recording medium.
2. Description of the Related Art
In general, repetitively rewritable optical recording media, i.e., optical disks may be sorted into CD-RW (Rewritable Compact Discs) and rewritable digital versatile discs (DVD-RAM, DVD-RW and DVD+RW). In these rewritable optical disks, information writing/reading thereto/therefrom is performed repetitively according to typical use of the optical disk. The repetitive write/read of information causes a change of a mixing ratio from an initial mixing ratio of a recording layer mixture provided for recording the information, which leads to a loss of initial properties of the mixture. Such loss causes errors in writing/reading information, which is called degradation. Areas of the degradation are turned up as defective areas when formatting, writing or reading of the optical disk is carried out. Other than such degradation, defective areas of the rewritable optical disk are caused by scratches on a surface, dust, and/or production defects. Therefore, in order to prevent writing/reading data to/from the defective areas formed by the foregoing causes, management of the defective areas is required. To do this, as shown in
FIG. 1
, DMAs (Defect Management Areas) are provided in a lead-in area and in a lead-out area of the optical recording medium (for example, DVD-RAM) for managing the defective areas of the optical recording medium. And, data areas are managed in groups, each having a user area for actual writing of data thereon and a spare area for use in a case of defect occurrence in the user area. In general, there are four DMAs provided in one disk (for example, a DVD-RAM), two in the lead-in area and the other two in the lead-out area. As management of the DMAs is important, the same data is repeatedly written in the four DMAs for protection of data. Each DMA has two blocks having 32 sectors total, i.e., one block has 16 sectors. A first block (called as a DDS/PDL block) of each DMA has a DDS (Disc Definition Structure) and a PDL (Primary Defect List), and a second block (called as an SDL block) of each DMA has an SDL (Secondary Defect List). The PDL denotes a primary defect data storage, and the SDL denotes a secondary defect data storage.
In general, the PDL stores entries of defects which occurred during fabrication of the disk, and all defective sectors identified in formatting, i.e., initializing and re-initializing, the disk. As shown in
FIG. 2A
, each entry has an entry type and a sector number of a defective sector.
The PDL is further divided into a P-list, a G
1
-list, and a G
2
-list. Defective sectors defined by disk fabricators, for example defective sectors from a disk fabricating process, are stored in the P-list. Defective sectors found during a certification process are stored in the G
1
-list. Defective sectors transferred to the SDL directly without the certification process are stored in the G
2
-list. The entry type indicates an origin of the defective sector occurrence, for example, if the entry type is ‘
10
b
’, the origin of the defective sector occurrence is sorted to be P-list, and if the entry type is ‘
10
b
’, the origin of the defective sector occurrence is sorted to be G
1
-list, and if the entry type is ‘
11
b
’, the origin of the defective sector occurrence is sorted to be G
2
-list.
On the other hand, the SDL, listed in block units, stores entries of defective areas occurring after formatting, or defective areas which cannot be listed on the PDL during formatting. As shown in
FIG. 2B
, each of the SDL entries has an area for storing a sector number of a first sector of a block having the defective sector therein and an area for storing a sector number of a first sector of a replacement block to replace the defective block. Initialization of the disk includes initialization and re-initialization. During re-initialization, full formatting, such as an initial formatting, occurs including partial certification in which the initialization is done partially, and an SDL is transferred to the G
2
-list in the PDL. A conversion of the SDL to G
2
-list (called a simple formatting hereafter), without certification shortens the duration of formatting. The P-list is unchangeable by any formatting. Since the defective blocks on the SDL are stored as in units of sectors (i.e., all sectors in a “defective” block), the G
2
-list may contain good sectors as well as the defective sectors which cause the block to be “defective.”
For example, as shown in
FIG. 3A
, in the partial formatting, sectors on the P-list and the G
1
-list before formatting remain on the P-list and the G
1
-list as they are, and the old G
2
-list and defective blocks listed on the SDL before formatting go through a certification process. After all entries on the G
2
-list and SDL are erased, only defective sectors found in the certification process are listed on the G
1
-list. The defective blocks listed on the G
2
-list or the SDL may also include sectors without defects. If the G
1
-list overflows, the rest is listed on a new SDL, and the G
2
-list has a null data inserted therein.
As shown in
FIG. 3B
, in the simple or quick formatting in which the SDL is converted into the G
2
-list without a certification process, sectors on the P-list, G
1
-list and G
2
-list before formatting are maintained on the P-list, G
1
-list and G
2
-list as they are after formatting. The old SDL entries are converted into 16 PDL entries, and listed on the G
2
-list after the old SDL entries are erased. In this instance, if the G
2
-list overflows, the rest of the SDL entries not listed on the G
2
-list are listed on a new SDL. The overflow occurs because the number of entries which can be listed on the PDL is limited by a DMA processing condition. The following equation (1) shows one example of the DMA processing condition.
S
PDL
+S
SDL
≦16 sectors (1
≦S
PDL
≦15, and 1
≦S
SDL
≦15)  (1)
where
,
S
PDL
=
⌊
(
E
PDL
×
4
+
4
)
+
2047
2048
⌋
,
and
 
S
SDL
=
⌊
(
E
SDL
×
8
+
24
)
+
2047
2048
⌋
.
S
PDL
is a number of sectors used for maintaining PDL entries; S
SDL
is a number of sectors used for maintaining SDL entries, E
PDL
is a number of PDL entries; and E
SDL
is a number of SDL entries. And, └P┘ for some real number P denotes the greatest integer not greater than P. That is, the equation (1) determines a number of total sectors which can be used both for PDL and SDL, and that number cannot be greater than 16. A number of sectors which can be used either for PDL or SDL cannot be greater than 15.
In the meantime, the defective areas (i.e., defective sectors or defective blocks) in the data area should be replaced with good areas, according to a slipping replacement algorithm or linear replacement algorithm.
Referring to
FIG. 4A
, in the slipping replacement which is applicable to a case when a defective area is listed on the PDL, if the defective sector is present in the user area on which an actual data is to be written, the defective sector is skipped, and instead, the data is written on a good sector next to the defective sector. Therefore, the user area having the data written thereon is pushed back to occupy as many spare areas as the skipped defective sectors, at the end. That is, the user area slips into the spare area as many as the sectors listed on the PDL.
And, referring to
FIG. 4B
, in the linear replacement which is applicable to a case when a defective area is listed on the SDL, if a defective block is present in the user area, the defective block is replaced with block units of replacement areas assigned to the spare area in writing the data. If the replacement block listed on the SDL is found to be defective later, a direct pointer method is applied to the SDL. That is, by the direct pointer method, the defective block is replaced with a new replacement block and the SDL entr

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