Dynamic information storage or retrieval – Condition indicating – monitoring – or testing – Including radiation storage or retrieval
Reexamination Certificate
1999-08-16
2002-07-02
Edun, Muhammad (Department: 2653)
Dynamic information storage or retrieval
Condition indicating, monitoring, or testing
Including radiation storage or retrieval
C369S053170, C369S047140
Reexamination Certificate
active
06414923
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical recording medium, and more particularly, to a recording/reproducing method of a rewritable optical recording medium.
2. Background of the Invention
In general, there are rewritable compact disc, and rewritable digital versatile disc (DVD-RW, DVD-RAM, DVD+RW) in optical recording mediums, particularly, in optical disks, which are rewritable freely and repetitively. In those rewritable optical disks, information writing /reading thereto/therefrom are made repetitively. As the nature of use of the optical disk is, the repetitive write/read of information causes a change of a mixing ratio of a recording layer mixture provided for recording the information from an initial mixing ratio, which leads to a loss of initial properties of the mixture that causes an error in writing/reading information, which is called degradation. Areas of the degradation are turned up as defective areas when formatting, or write or read command for the optical disk is carried out. Other than the degradation, defective areas on the rewritable optical disk are caused by scratches on a surface, dusts, and/or from 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 lead-in areas and in lead-out areas of the optical recording medium for managing the defective areas on the optical recording medium. And, data areas are managed in zones (or groups), each having a user area for use in actual writing of data 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 in total, i.e., one block has 16 sectors. A first block of each DMA (called as DDS/PDL block) includes a DDS (Disk Definition Structure) and a PDL (Primary Defect List), and a second block (called as SDL block) of each DMA includes an SDL (Secondary Defect List). The PDL is a primary defective data storage portion and the SDL is a secondary defective data storage portion. In general, the PDL is a storage of entries of all defective sectors identified in formatting, i.e., initializing and re-initializing, of the disk. Each entry has an entry type and a sector number corresponding to a defective sector. On the other hand, the SDL, listed in block units, is a storage of entries of defective areas occurred after the formatting, or defective areas which can not be stored in the PDL during the formatting.
As shown in
FIG. 2
, each SDL entry has an area in storage of a sector number of a first sector in a block having a defective sector occurred therein and the other area in storage of a sector number of a first sector in a spare block which will replace the defective block. And, one bit is assigned to each entry for FRM (Forced Reassignment Marking); if the one bit is
0
b
, it indicates that a spare block is assigned and the spare block has no defects, but if the bit is
1
b
, it indicates that no spare block is assigned, or an assigned spare block is defective. The defective areas (i.e., defective sectors or defective blocks) in the data area are replaced with good areas, according to a slipping replacement algorithm or linear replacement algorithm.
Referring to
FIG. 3A
, in the slipping replacement which is applicable to a case when a defective area is listed on the PDL, if the defective sector listed on the PDL is present in the user area on which an actual data is to be written, the defective sector is skipped, and instead, the defective sector is replaced with a good sector next to the defective sector in writing a data. Consequently, the user area on which the data is being written is pushed backward, to occupy the spare area as much as the skipped defective sector, at the end. That is, the spare area is assigned to the user area as much as the skipped defective sectors. For example, if there are two defective sectors listed on the PDL, the data is written pushed back by two sectors into the spare area.
And, referring to
FIG. 3B
, in the linear replacement which is applicable to a case when a defective area is listed on the SDL, if there is a defective block listed on the SDL, the defective block is replaced with block units of replacement areas assigned to the spare area in writing the data. Though a PSN (Physical Sector Number) assigned to the defective block is not changed, an LSN (Logical Sector Number) is transferred to the replacement block, together with the data. This linear replacement is effective in non-realtime writing/reading a data.
FIG. 4
illustrates a block diagram showing one example of a recording portion in a related art optical recording/reproduction device provided with an optical pickup for writing/reading a data to/from an optical recording medium, a pickup mover for moving the optical pickup, a data processor for processing and providing an input data to the optical pickup or processing a data read or received from the optical disk through the optical pickup, an interface, and a microcomputer for controlling the above units. A host is connected to the interface of the device for recording/reproducing a data to/from an optical recording medium for exchange of command and data.
Referring to
FIG. 4
, when a data to be written is provided to the host, the host provides a write command to the device for recording/reproducing a data to/from an optical recording medium, together with the data to be written. Upon reception of the data to be written on the optical recording medium, the recording/reproducing device writes the data starting from a position designated by the write command. In this instance, the recording/reproducing device writes no data on defective areas utilizing the PDL and the SDL which indicate defects on the optical recording medium. That is, physical sectors listed on the PDL are skipped in the writing, and, as shown in
FIG. 5A
, physical blocks sb
1
kA and sb
1
kB listed on the SDL are replaced with replacement blocks sb
1
kD and sb
1
kF assigned to the spare area in the writing. In this instance, as shown in
FIG. 5B
, (0, sb
1
kA, sb
1
kF) and (0, sb
1
kb, sb
1
kD) are left on the SDL entry. The (0, sb
1
kA, sb
1
kF) indicates that a spare block without defects is assigned and a data to be written on a defective block sb
1
kA in a user area is written on a replacement block sb
1
kF in a spare area. And, in the writing or reading, if a defective block not listed on the SDL, or a block with a high possibility of error occurrence is present, the block is taken as a defective block, a replacement block is located in the spare area, data of the defective block is written again in the replacement block, and a first sector number of the defective block and a first sector number of the replacement block are listed in association with each other on the SDL entry.
In this instance, in order to write data while replacing the defective block listed on the SDL with a replacement block assigned to the spare area, the optical pickup must be shifted to the spare area and returned back to the user area again. However, a time period required for the shifting and returning back is a great obstacle for realtime writing. Accordingly, different methods for managing a defective area applicable to the case when a realtime writing is required, such as A/V (for example, movies), are suggested. One of the methods is the skipping method in which no linear replacement is employed in using the SDL, but a data is written on a good block next to an encountered defective block as shown in FIG.
6
. In the skipping method, not only the defective block listed on the SDL, but also a new defective block not listed on the SDL
Jeong Kyu Hwa
Park Yong-Cheol
Shin Jong In
Birch & Stewart Kolasch & Birch, LLP
Edun Muhammad
LG Electronics Inc.
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