Information recording medium, information recording method,...

Details Information recording medium, information recording method,... Information recording medium, information recording method,...

2000-06-12

2001-09-25

Hindi, Nabil (Department: 2753)

Dynamic information storage or retrieval

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

By medium defect indicative control signal

C369S053170

Reexamination Certificate

active

06295257

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an information recording medium, an information recording method, an information recording apparatus and an information reproducing apparatus.
2. Description of the Related Art
An optical disk is a type of information recording medium which has a sector structure. In recent years, as the recording density and the capacity of an optical disk have been increased, it has become more important to ensure the reliability thereof. In order to ensure the reliability, an optical disk apparatus performs defect management in which a sector on the disk which cannot be used for recording/reproduction (hereinafter, referred to as a “defective sector”) is replaced by another sector having a good condition. One standard for such defect management is ISO/IEC 10090 for 90 mm optical disks (hereinafter, referred to as the “ISO standard”), which is published from International Standards Organization (ISO).
As the first prior art example, an ECC block which is used by a DVD standard and the defect management method according to the ISO standard will be briefly described below.
FIG. 17
illustrates a physical structure of a disk
1
. The disk
1
has a plurality of tracks
2
provided in the form of concentric circles or a spiral. Each of the tracks
2
is divided into a plurality of sectors
3
. The disk
1
includes one or more disk information areas
4
and a data recording area
5
.
The disk information area
4
stores various parameters needed to access the disk
1
. In the example illustrated in
FIG. 17
, two disk information areas
4
are provided respectively along the inner and outer peripheries of the disk
1
. The disk information area
4
along the inner periphery is also called a “lead-in” area, while the disk information area
4
along the outer periphery is also called a “lead-out” area.
Data is recorded/reproduced on/from the data recording area
5
. Each sector
3
in the data recording area
5
is assigned an absolute address which is called a “physical sector number”.
FIG. 18A
illustrates a structure of an ECC (error correcting code) block which is a unit of error correcting code calculation. An ECC block contains main data (172 bytes×48 rows), an inner code parity PI obtained by calculating error correcting codes for each row (in the horizontal direction), and an outer code parity PO obtained by calculating error correcting codes for each column (in the vertical direction).
An error correction method using such inner and outer parities is generally called a “product code-based error correction method”. The product code-based error correction method is an error correction method which is effective for both random errors and burst errors (a group of localized errors). For example, consider a case where some random errors occurred, as well as two rows of burst errors due to a scratch made on the disk
1
. Most of such burst errors are correctable using the outer codes, because they are 2-byte errors in the vertical direction. A column with many random errors may not completely be corrected by outer codes. Some errors may remain after an error correction operation using outer codes. However, such remaining errors are in most cases correctable using inner codes. Even if some errors still remain after the error correction operation using inner codes, such errors can further be reduced by performing an error correction operation using outer codes again. By employing such product codes, DVDs realize a sufficient error correction capability while saving the parity redundancy. In other words, the capacity for user data is increased by such saving of the parity redundancy.
In a larger capacity DVD, each ECC block includes
16
sectors so as to realize both an increased error correction capability and a reduced redundancy. The ECC block illustrated in
FIG. 18A
includes only 4 sectors for the sake of simplicity.
FIG. 18B
illustrates an arrangement of sectors included in an ECC block. The outer code parities PO of the ECC block are divided into rows and proportionally distributed among the sectors. As a result, each recording sector includes data of 182 bytes×13 rows.
An upper level control unit (this generally corresponds to a host computer) instructs an optical disk apparatus to record or reproduce data by sectors. When instructed to reproduce data from a sector, the optical disk apparatus reproduces an ECC block including the sector from the disk, performs error correction on the reproduced data, and returns only a portion of the data which corresponds to the designated sector. When instructed to record data on a sector, the optical disk apparatus reproduces an ECC block including the sector from the disk, performs error correction on the reproduced data, and replaces a portion of the data which corresponds to the designated sector with recording data which has been received from the upper level control unit. Then, the optical disk apparatus re-calculates error correcting codes for the ECC block and adds them to the ECC block, before the ECC block including the designated sector is recorded on the disk. Particularly, such a recording operation is called a “read modified write” operation.
In the following description, a “block” means an ECC block as described above.
FIG. 19
illustrates an exemplary physical space of the disk
1
for use with the defect management method according to the ISO standard. The data recording area
5
includes a volume space
6
and a spare area
9
.
The volume space
6
is managed by consecutive addresses, called “logical sector numbers”. The volume space
6
includes a logical volume space
6
a
and logical volume structures
6
b
for storing information on the structure of the logical volume space
6
a.
The spare area
9
includes at least one sector (for example, #1 spare block) which may be used in place of a defective sector if such a defective sector occurs in the volume space
6
.
In the example illustrated in
FIG. 19
, a file A (indicated as “File-A” in
FIG. 19
) exists directly under a root directory (indicated as “ROOT” in FIG.
19
). Among data blocks a to a included in the data extent of the root directory, the data block c is defective. The defective block c is replaced by #1 spare block in the spare area
9
. Among data blocks d to g included in the data extent of the file A, the data block f is defective. The defective block f is replaced by #2 spare block in the spare area
9
.
The replacement of each defective block by a spare block in the spare area
9
is registered in a secondary defect list (“SDL”). The SDL is stored in a defect management information area as a part of defect management information.
More recently, there is an attempt in the art to use a rewritable optical disk in a less expensive form of a bare disk with no cartridge, as a read-only optical disk. In view of the defect management, however, a bare disk is more likely to get fingerprints thereon, and the number of defective sectors may increase unexpectedly. Therefore, it is proposed in the art to use a dynamically expandable spare area rather than a fixed spare area.
Moreover, the increased capacity of an optical disk, along with the motion picture compression technique having been put into practical use, has paved the way to recording/reproduction of motion pictures on/from an optical disk. However, the conventional defect management method may not be suitable for such a motion picture application, in which real time processing is required. In particular, if a defective sector is replaced by a spare sector which is physically distant from the defective sector, it may take too much time to move the optical head to such a distant spare sector for ensuring the real time processing. Therefore, it has been proposed in the art to employ a new defect management method instead of the conventional method where a defective sector is replaced by a physically distant spare sector.
As the second prior art example, a proposed method for recording/reproducing AV data (i.e.

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