Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1999-12-16
2002-12-10
Tran, Thang V. (Department: 2653)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S047140
Reexamination Certificate
active
06493301
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical recording medium and particularly to a method of managing the defect area and method of controlling the recording/playback operation of the optical recording medium.
2. Discussion of Related Art
An optical storage medium is generally divided into a read only memory (ROM), a write once read many (WORM) memory into which data can be written one time, and rewritable memories into which data can be written several times. Rewritable optical storage mediums, i.e. optical discs, include rewritable compact discs (CD-RW) and rewritable digital versatile discs (DVD-RW, DVD-RAM, DVD+RW).
The operations of writing and playing back data in a rewritable optical disc may be repeated. This repeated process alters the ratio of storage layers for recording data into the optical disc from the initial ratio. Thus, the optical discs lose their characteristics and generate an error during recording/playback. This degradation is indicated as a defective area at the time of formatting, recording on or playing back from an optical storage medium. Also, defective areas of a rewritable optical disc may be caused by a scratch on its surface, particles of dirt and dust, or errors during manufacture. Therefore, in order to prevent writing into or reading out of the defective area, management of such defective areas is necessary.
FIG. 1
shows a defect management area (DMA) in a lead-in area and a lead-out area of the optical disc to manage a defect area. Particularly, the data area is divided into a plurality of zones, where each zone is further divided into ‘a user area’ and ‘a spare area.’ The user area is where data is actually written and the spare area is used when a defect occurs in the user area.
There are four DMAs in one disc, e.g. DVD-RAM, two of which exist in the lead-in area and two exist in the lead-out area. Because managing defective areas is important, the same contents are repeatedly recorded in all four DMAs to protect the data. Each DMA comprises two blocks of
32
sectors, where one block comprises
16
sectors. The first block of the DMA, called a DDS/PDL block, includes a disc definition structure (DDS) and a primary defect list (PDL). The second block of the DMA, called an SDL block, includes a secondary defect list (SDL). The PDL corresponds to a primary defect data storage and the SDL corresponds to a secondary defect data storage.
The PDL generally stores entries of defective sectors caused during the manufacture of the disc or identified when formatting a disc, namely initializing and re-initializing a disc. Each entry is composed of an entry type field and a field for a sector number corresponding to a defective sector. The SDL lists defective areas in block units, thereby storing entries of defective blocks occurring after formatting or defective blocks which could not be stored in the PDL during the formatting. Each SDL entry has a field for storing a sector number of the first sector of a block having defective sectors, a field for storing a sector number of the first sector of a block replacing the defective block, and reserved areas. Accordingly, defective areas, i.e. defective sectors or defective blocks, within the data area are replaced with normal or non-defective sectors or blocks by a slipping replacement algorithm and a linear replacement algorithm.
The slipping replacement algorithm is utilized when a defective area is recorded in the PDL. As shown in
FIG. 2A
, if defective sectors m and n, corresponding to sectors in the user area, are recorded in the PDL, such defective sectors are skipped to the next available good sector. By replacing the defective sectors by subsequent good sectors, data is written to a normal sector. As a result, the user area into which user data is written slips and occupies the spare area in the amount equivalent to the skipped defective sectors. For example, if two defect sectors are registered in the PDL, the user data would slip and occupy two sectors of the spare area.
The linear replacement algorithm is utilized when a defective block is recorded in the SDL or when a defective block is found during playback. As shown in
FIG. 2B
, if defective blocks m and n, corresponding to blocks 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.
As defective areas are compensated utilizing the spare area, methods of assigning the spare area play an important role in the defective area management. Typically, the spare area may be allocated in each zone or group of the data area or may be allocated in a designated portion of the data area.
One method of allocating the spare area is to allocate the spare area at the top of the data area, as shown in FIG.
3
(
a
). In such case, the spare area is called a Primary Spare Area. Namely, the data area excluding the primary spare area becomes the user area.
The primary spare area, assigned in an initial formatting process, is assigned when a manufacturer produces the optical disc or when a user initially formats an empty disc. A variety of sizes can be allocated for the primary spare area. For example, in order to provide a 4.7 GB(Giga byte) initial data recording capacity (i.e. initial user area) in a disc with a size of 120 mm, 26 MB (Mega Byte) may be allocated for the primary spare area. Moreover, a supplementary spare area may be additionally assigned near the bottom of the data area, as shown in FIG.
3
(
b
), if necessary.
When a rewritable optical disc is loaded, the defect information registered in the lead-in area (or lead-out area) of the DMA is first read and recorded in a specified location of the system memory of a drive. The maximum DMA storage capacity to store the defect information in the system memory of a drive, for example 32 KB (Kilo bytes), is predetermined. Thus, DMA processing conditions are given to satisfy the predetermined DMA storage capacity. The conditions are expressed below in Equation 1, where S
PDL
denotes the number of sectors used for maintaining the PDL entries, S
SDL
denotes the number of sectors used for maintaining the SDL entries, E
PDL
denotes the number of PDL entries, and E
SDL
denotes the number of SDL entries.
1
≦S
PDL
≦15 (or 16)
1
≦S
SDL
≦15 (or 16)
S
PDL
+S
SDL
≦16 sectors
S
PDL
=[(
E
PDL
×4+4)+2027]/2048
S
SDL
=[(
E
SDL
×8+24)+2027]/2048 [Equation 1]
Referring to Equation 1, a DMA storage capacity which satisfies the conditions, 1≦S
PDL
≦15 and 1≦S
SDL
≦15, is 32 KB (2048*16). This is because one sector corresponds to 2048 Bytes and the number of total sectors which can be used for the PDL and SDL cannot exceed 16 sectors, i.e. S
PDL
+S
SDL
≦16 sectors. The DMA storage capacity satisfying the conditions, 1≦S
PDL
≦16 and 1≦S
SDL
≦16, is 64 KB (=(2048*16)+(2048*16)) because only one condition that the PDL or SDL cannot exceed 16 sectors is present. Thus, the DMA storage capacity varies with the DMA conditions.
However, during a formatting of an optical disc, an overflow may be caused by a limited number of entries which can be registered in the PDL according to Equation 1. This is because the DMA conditions do not take into consideration the size of the spare area. In other words, advancement of technology will continuously produce an optical recording medium with greater capacity or an optical recording media with the same format but different sizes and recording capacity. This would result in a variation of the standard, size and recording capacity of the optical medium. For each variation, the size of the spare area and the DMA condition should be determined for the new optical recording medium. Nevertheless, there has been no standard for determining the size of the spare area and DMA condition.
SUMMARY OF THE INVENTION
Accordin
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
Tran Thang V.
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