HK1036681B - Recording medium having spare area for defect management and method of allocating spare area - Google Patents

Description

Optical disc having defect management area and method of allocating spare area

This application is a divisional application of a patent application having an application date of 10/11/1999, an application number of 99125009.5, entitled "recording medium with defect management spare area and method of allocating spare area".

Technical Field

The present invention relates to an optical recording medium, and more particularly, to an optical disc having a spare area for defect management, and a method of allocating the spare area.

Background

In order to manage defects on a general recordable/rewritable optical disc, for a defect (main defect) generated at the time of initialization of the optical disc, the defect is skipped using slipping replacement without providing a logical sector number to the defect; for defects (sub-defects) generated during the use of the optical disc, an Error Correction Code (ECC) block of an erroneous section is replaced with a normal block in a spare area using a linear replacement (linear replacement) method.

Specifically, slipping replacement is used to reduce the speed degradation in recording or reproduction due to the presence of a defect, in which data is recorded or reproduced by providing a logical sector number to be provided to a sector which has been confirmed as defective during a confirmation process of checking the defect of the optical disc when the optical disc is initialized, to a sector adjacent to the defective sector, that is, a sector in which a defect is generated during slipping recording or reproduction. Here, the sector number assigned by skipping the defective sector is shifted into an actual physical sector number. This runback phenomenon is solved by using as many sectors as there are defects in a spare area at the end of a corresponding recording area (group or zone). According to the description, the position of the defective sector replaced by slipping replacement is recorded in a main defect table (PDL) of a Defect Management Area (DMA) on the optical disc.

Slipping replacement cannot be used for defects that occur while the optical disc is being used. If a defective part is ignored or skipped, a discontinuity in the logical sector numbers occurs, which means that the slipping replacement violates file system rules. Therefore, a linear replacement method is used for defects generated during the use of the optical disc, in which ECC blocks including defective sectors are replaced with ECC blocks in a spare area. The specified location of the defective block replaced by the linear replacement is recorded in a secondary defect table (SDL) in a Defect Management Area (DMA) on the optical disc. If linear replacement is used, the logical sector numbering is not interrupted. However, if defective, the locations of the sectors on the disc are discontinuous again, and the actual data of the defective ECC block appears in the spare area.

Meanwhile, according to the 1.0 version standard of the DVD-RAM, a digital versatile disc random access memory (DVD-RAM) is constructed of a plurality of groups, each group having a user area and a spare area constant in each Zone (Zone). Fig. 1A is a half plan view of an optical disc showing a user area, a protection area and a spare area, and fig. 1B shows sectors on an optical disc from one dimension. Each section includes a protection area, a user area, a spare area, and a protection area arranged in sequence.

An optical disc is divided into zones in order to solve inaccurate recording due to variation in spindle speed during recording, and a Zone Constant Linear Velocity (ZCLV) method is used in order to increase a search speed associated with the constant linear velocity method.

In particular, if the defect is managed by linear replacement, since the linear velocity of the optical disc does not change, linear replacement within one defective section is likely to increase the search speed. Therefore, the DVD-RAM allocates a certain spare area for each sector, as shown in fig. 1B, to complete the linear replacement.

In the existing defect management method, each zone is used as one group, and one spare area is allocated at the end of each group. Each group is managed as a defect management area. Further, since the starting sector number of each group is predetermined, one ECC block is considered as a unit of a physically divided area, i.e., the start of the starting position of the sector.

The starting logical sector number for each group is specified as described above. Therefore, if defects are managed by slipping replacement, slipping replacement must be performed in only one corresponding group. In order to replace a defect generated in a corresponding group using the slipping replacement method, the slipped defect sector number must be smaller than the available sector number within the spare area in the corresponding group. Accordingly, the maximum size of a defect that can be replaced by slipping is also limited due to the limitation that large defects generated in one group must be handled within the group.

If the size of a defect to be replaced by slipping replacement is larger than that of a spare area in a corresponding group, a spare area in another group must be used by linear replacement. However, if linear replacement is used, the management of defects is not in units of sectors, but in units of ECC blocks, that is, in units of 16 sectors. Therefore, one spare area of 16 sectors is required to process one defective sector, which reduces the efficiency of defect management.

In addition, a standard size of a spare area for defect management is predetermined, so that for a case where defect management using linear replacement is not applicable, such as real-time recording, spare areas of the same size must be allocated. Therefore, the area utilization efficiency of one optical disc is lowered.

Disclosure of Invention

To solve the above problems, it is an object of the present invention to provide a method of efficiently and flexibly allocating a spare area by generating a plurality of sectors as a group, allocating a spare area for slipping replacement in advance, and allocating a spare area for linear replacement in the future.

Accordingly, to achieve the object of the present invention, the present invention provides a method of allocating a spare area for an optical disc having a defect management spare area, wherein the optical disc includes a user data area formed of a plurality of sectors into one group and a main spare area for defect management of the optical disc, the method comprising the steps of: during the use of the optical disc, an additional spare area for linear replacement for defect management is allocated at the last of the user data area of the optical disc.

The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings.

Drawings

Fig. 1A is a half plan view of an optical disc having a user area, a protection area and a spare area; and

FIG. 1B shows a one-dimensional structure of sectors of a DVD-RAM disc;

FIGS. 2A and 2B illustrate allocation of a spare area at initialization according to the present invention;

FIG. 2C shows allocation of spare areas during use after initialization; and

FIGS. 3A and 3B show a discontinuity of one ECC block in a sector caused by a defective sector based on slipping replacement;

FIG. 4 is a flowchart illustrating a method of allocating a spare area during initialization according to an embodiment of the present invention;

fig. 5 is a flowchart illustrating a method of allocating a spare area during post-initialization use according to an embodiment of the present invention.

Detailed Description

In accordance with a detailed description of preferred embodiments of the present invention, the spare areas for defect management on the optical disc according to the present invention include a primary spare area, a secondary spare area, and an additional spare area.

When the disc is initialized, a primary spare area is first allocated for defect management and first used for slipping replacement. The spare area remaining after slipping replacement can be used as a secondary spare area for linear replacement. And a sub spare area for linearly replacing a defect generated during use of the optical disc, indicating an area remaining after the main spare area is used for slipping replacement during initialization. The sub spare area may also represent a separately allocated spare area. The additional spare area, which is used to linearly replace a defect generated while the optical disc is in use, indicates a spare area additionally allocated while the optical disc is in use after initialization.

Specifically, in the present invention as shown in fig. 2A, a group is formed by a plurality of zones on the optical disc, and during initialization, at the end of each group, a spare area (primary spare area) is first allocated for slipping replacement. The slipping replacement is replaced in units of sectors, thereby improving the utilization efficiency of the spare area. However, in the slipping replacement process, only the defective sector is not used, and data starts to be recorded in the next normal sector, so that the defective area cannot be used after initialization.

During initialization, as many spare areas as possible are allocated as the primary spare areas for slipping replacement, but the remaining primary spare areas after slipping replacement may be used as secondary spare areas for linear replacement. If it is determined that the secondary spare area allocated in the primary spare area is insufficient for linear replacement after slipping replacement is completed only when the disc is initialized, the secondary spare area for linear replacement may be further allocated to a zone in units of zones, as shown in fig. 2B. The sub spare area has no logical sector number, and information about the allocation of the sub spare area is stored in and managed by a Defect Management Area (DMA). The secondary spare area allocated during initialization is mainly disposed at the end of one section, although it is not necessary to allocate the secondary spare area in each section. Since the spare area for linear replacement is allocated at the end of one sector, it is easy to control. Further, since the spare area is controlled in units of sectors, the spare area closest to the location where the defect is generated can be easily found in the sectors. In addition, modifications to existing DMA information may be minimized.

The secondary spare area may be disposed before a protection area, which is the last part of a zone. When the secondary spare area is disposed in each zone, its size may be predetermined to a relative or absolute size according to a numerical expression (e.g., 3% of each zone).

When one optical disc is being used after initialization, if the spare area allocated in units of extents for linear replacement is insufficient, a predetermined number of additional spare areas are allocated for linear replacement, starting from the highest position of the logical file area in one file system, as shown in fig. 2C. During linear replacement, the additional spare area is used in reverse order (reverse order) starting from the last position of the logical file area, thereby solving the discontinuity problem of the logical file area.

Linear replacement is performed in units of ECC blocks, and thus the entire spare area of one ECC block is used even when one sector is defective. In the linear replacement process, a defective block is replaced by a physically separated spare area, so that a search speed when searching for a defective section is low. However, the linear replacement can react to a defect generated while the optical disc is being used, so it can also be used for a side defect generated during the use of the optical disc.

At the rear of the logical file area, how large an empty contiguous area is, how large additional spare area is allocated. The maximum size of the additional spare area must be smaller than the area of the last sector. Here, the logical file area means a logical area in the middle of the entire area used in a file system in which user data files can be recorded/reproduced.

In an 80mm diameter optical disc, since the 80mm diameter optical disc is affected by the rapid double refraction from a radius of about 38mm due to the insertion of the optical disc, the radius of one user data area must be a maximum of not more than 38 mm.

If a spare area for slipping replacement is allocated at the end of the optical disc by a method of forming a group from a plurality of sectors according to the present invention, a spare area whose size is large enough to be processed in a group, which is the maximum number of defects processed using a main defect table (PDL), is allocated for 7679 entries (15 sectors) at most. In this case, it is also necessary to allocate a spare area (a spare area for a control block location) to prevent a shifted-backward phenomenon of a logical sector number at a boundary between sectors due to slipping replacement, resulting in an ECC block not starting from the start position of a sector.

For example, when the optical disc applied to the present invention is a 1.46gb (gigabytes) DVD-RAM, the main spare area allows PDL entries (entries) of 8 sectors and SDL entries (entries) of 64 sectors to be processed, thereby preventing an alarm from being generated immediately after formatting due to lack of the main spare area. Here, the alarm level is generated when the spare area is smaller than 32 ECC blocks. Accordingly, more than 3% of each zone is allocated as one primary spare area, considering the number of defects generated in the spare area and the size of the spare area for preventing discontinuity of ECC blocks in each zone.

A PDL item that can be handled by the main active area corresponds to between one sector and 8 sectors, and an SDL item is between one sector and 8 sectors. The PDL item is processed (S)_PDL) And processes the SDL item (S)_SDL) The spare area of (a), can be represented by the following inequality 1:

1≤S_PDL≤8 1≤S_SDL≤8 …(1)

the phenomenon of logical sector number move-back due to slipping replacement, which may occur at the boundary between sectors, is now described with reference to fig. 3A and 3B.

In the proposed group formed of a plurality of sectors according to the present invention, when there is a defective sector in sector # n, as shown in fig. 3A, the remaining sectors where no ECC block unit is formed are located at the end of the sector due to slipping replacement. When data is written to the remaining sectors that do not form the ECC block unit, a shift-backward (shifted-backward) phenomenon of the logical sector number due to slipping replacement occurs at the boundary between the sectors, so that discontinuity of the ECC block may occur at the boundary between the sectors, as shown in fig. 3B. That is, one ECC block may be located within two sectors. In this case, a problem occurs in that the optical disc must be driven at different speeds to read or write one ECC block located in two sectors, and one user area and one guard area must be separately processed since the physical sector numbers are consecutive therebetween. The guard area is a buffer area for preventing unstable operation due to a difference in rotational speed between sectors.

In the present invention, if the remaining sectors at the end of one sector are smaller than the number of sectors (16 sectors) used to form one ECC block due to the generation of defective sectors, they are not used and are skipped. The size allocated to a spare area must be as large as expressed in the following equation 2 in order to control an ECC block to start at the start position of a sector in response to a logical sector number back shift phenomenon that may occur at the boundary between sectors due to slipping replacement;

spare area (number of sectors-1) × (number of sectors per error correction block-1) … 2 for block position control

In a DVD-RAM disc, an ECC block has 16 sectors, so if an ECC block does not start at the start of a session, a maximum of 15 sectors may remain at the end of the session. The remaining sectors, which do not form one ECC block at the end of each sector, must also be skipped in order to match the start position of the ECC block with the start position of the sector, thus requiring a spare area of the same size as the skipped sectors. The number of boundaries between segments can be found by subtracting 1 from the number of segments. That is, if there are two sections, the number of the inter-section connecting portions is 1, and if there are three sections, the number of the inter-section connecting portions is 2. As large as one ECC block, a spare area for block location control may be allocated mainly to each zone.

Therefore, it is preferable that only one set of one optical disc is used for slipping replacement. In this case, a spare area for slipping replacement may be allocated at the end of the disc, considering the number of items that may be processed using PDL and SDL, and the size of the spare area for controlling the start position of one ECC block at the boundary between zones (here, a maximum of 32 ECC blocks).

In this way, a plurality of sectors are set as a group, and a spare area for slipping replacement is allocated at the end of the group. Therefore, when there are a plurality of groups each having a plurality of sectors, since the size of the spare area allocated in each group is small, the reduction in the capability of eliminating burst errors due to large scratches is solved.

For example, in an optical disc with a capacity of about 4.7GB, there is one group in each sector, one group consisting of about 1600 tracks, and the width of each track on a physical disc is about 1mm, as shown in fig. 1A. If a scratch greater than 1mm is generated on the optical disc in the radial direction, about 1600 sectors may have defects. However, if the spare area generates one group in each zone and is allocated at a certain ratio according to the capacity of the optical disc, it can be determined that only about 1100 sectors are likely to be slipping-replaced in the inner circumferential portion of the optical disc. Therefore, approximately 400 to 500 remaining sectors cannot be replaced by the slipping replacement method, but are replaced by the linear replacement method. In this case, about 400 to 500 ECC blocks are required for the spare area and the performance of the disc at the section where the corresponding defect occurs is greatly reduced. However, when a large spare area is allocated for the entire optical disc for slipping replacement according to the present invention, slipping replacement can be performed even for such a large defect.

Fig. 4 is a flowchart illustrating a method of allocating a spare area to an optical disc during initialization according to an embodiment of the present invention. Referring to fig. 4, when an initialization command is received at step S101, a burst is generated from a plurality of extents of an optical disc in response to the initialization command, and a main spare area is allocated at the end of the burst at step S102. That is, the main spare area for slipping replacement includes one spare area for defect management, associated with 7679 data sectors (480 ECC blocks), where 7679 is the maximum number of defect management items that can be processed using PDL; and a spare area (here, a maximum of 32 ECC blocks) for controlling a start position of one ECC block at each boundary between sectors.

Meanwhile, in a 1.46GB DVD-RAM disc, the main spare area can handle 8 sectors of PDL entries and 64 SDL entries, and the spare area for block location control is also taken into consideration when allocating.

If the main spare area is allocated, it is determined whether a defect is generated with respect to the entire disc area, and the generated defect is replaced by slipping using the main spare area allocated at the end of the group at step S103. Here, if the allocated main spare area is insufficient to replace a defect by slipping, it is determined whether the corresponding optical disc is defective, and a step of generating an initialization error message to prevent the optical disc from being used may be further included.

If the slipping replacement is completed at step S103, a portion of the primary spare area that is not used during the slipping replacement is allocated to the secondary spare area for linear replacement, and if it is determined that the secondary spare area within the primary spare area is insufficient for linear replacement, the secondary spare area may be further allocated to the sector in units of sectors at step S104. Information on allocation of a sub spare area for linear replacement to a session in units of sessions is stored in a Defect Management Area (DMA) on the optical disc. When the allocation of the main standby area and the allocation of the sub standby area for linear replacement are completed, the initialization is completed. Preferably, the secondary spare area for linear replacement in the first spare area and the secondary spare area allocated to each zone are used in reverse order from the last of the corresponding spare areas, so as to unify the method of managing the additional spare area for linear replacement.

Fig. 5 is a flowchart illustrating a method of allocating a spare area when an optical disc is being used after having been initialized according to an embodiment of the present invention. If the size of the sub spare area allocated for linear replacement during disc initialization is insufficient to replace a defect generated during use of the initialized disc, an additional spare area for linear replacement is allocated.

In fig. 5, it is determined whether an additional spare area for linear replacement is required during the use of the optical disc at step S201. If it is determined that additional spare areas are required, it is determined whether there is a sufficient amount of continuous empty areas at the rear of one logical file area at step S202. If it is determined in step S202 that there is a sufficient amount of continuous empty area at the rear of the logical file area, an additional spare area of a predetermined size is allocated for linear replacement starting from the last of the logical file area in step S203, and then step S201 is performed again.

The allocation of the additional spare area corresponds to the reallocation of one logical file area generated after initialization, so that the help of the file system is required. In this case, an additional spare area for linear replacement is not allocated to each extent, but may be allocated from the rearmost direction of the logical file area, that is, from an area having the highest logical sector number in one logical file area, to which a user data file can be recorded, to an area having a lower logical sector number. When a side defect is generated and replaced by the linear replacement method through the additional spare area thus allocated, the search speed is hardly lowered, but the generation of a logical sector number area in a logical file area that cannot be used by the file system is prevented. That is, discontinuity of logical sector numbers can be prevented.

In the existing defect management method of linear replacement, a defective ECC block must be replaced by the first normal ECC block that has not been used between ECC blocks in a spare area, so that even when the spare area is used in order from the head, the defective block in the spare area is not managed and the defective spare area is skipped. However, as in the conventional method, if blocks within the additional spare area are used in order from the header, a problem occurs when the additional spare area is further increased. That is, as soon as the size of the additional spare area increases, information on the added additional spare area must be separately managed. To solve this problem, the blocks in the additional spare area are used in reverse order from the rear. Therefore, if only the highest sector number, from which the additional spare area starts, and the lowest sector number is detected, the entire additional spare area can be continuously managed. That is, a recording and/or reproducing apparatus does not need to know how frequently an additional spare area of a predetermined size is allocated, and can manage the additional spare area only by recognizing the start and end positions thereof. However, the maximum size of the additional spare area must be smaller than the last sector.

If it is determined at step S202 that there are not sufficiently continuous empty regions at the rear of the file system, the empty regions are disposed by the file system or an application at step S204. Thereafter, it is determined in step S205 whether there is a sufficient amount of continuous empty area. If there is a sufficient amount of continuous empty areas, the step S203 of allocating additional spare areas is performed. If the amount of continuous empty areas is not sufficient even after the empty areas are arranged, a message that "additional spare area cannot be allocated" is displayed at step S206. The process then terminates. The process also terminates if it is determined at step S201 that the additional spare area is not required.

Meanwhile, in a specific case, such as real-time recording or the like, a small spare area may be allocated for defect management, linear replacement with respect to a side defect is performed restrictively, and most defects may be handled by a file system or an application. Furthermore, it is preferable that the side defect is processed by a file system or an application based on real-time recording in order to obtain a minimum transmission speed required by the corresponding application.

In this case, it is also necessary for the recording and/or reproducing apparatus to detect defects and to perform minimum management with respect to the detected defects. Here, the minimum management means that SDL is used to manage as to whether the generated defect has been linearly replaced.

For example, for defects generated during the use of an optical disc having defect management information, in which defect management using linear replacement is not used for real-time recording, only a start sector number of each defective block is recorded in a Secondary Defect List (SDL), information indicating that the defective block has not been replaced is recorded in a Forced Reallocation Mask (FRM) bit in an SDL entry indicating whether the defective block has been replaced, and information indicating that the defective block has not been replaced is recorded in a start sector number of a replacement block in the SDL entry.

Since the recording and/or reproducing apparatus cannot recognize the defect contents handled by the file system or the application when the corresponding optical disc is reinitialized and used for another purpose, it can reinitialize the disc regardless of the generated defect. Accordingly, fast formatting cannot be performed in which a sub-defect (stored in the SDL entry) is simply changed to a PDL entry and is handled by slipping replacement, so that the recording and/or reproducing apparatus must manage the defect even when the sub-defect is managed by a file system or an application. Therefore, in all cases, it is necessary to control generation or non-generation of defects using the SDL regardless of whether linear replacement is performed or not, and whether a spare area for linear replacement exists or does not exist.

As described above, the present invention eliminates the restriction regarding the replacement of the maximum size of a defect by slipping, and does not violate the restriction that even a large defect generated in one group must be processed within the group, so that more effective slipping replacement can be performed. In addition, the size of the spare area may be appropriately adjusted according to the purpose of the application in order to more effectively utilize the area of the optical disc.

Claims (9)

1. A method of allocating a spare area for an optical disc having a defect management spare area, wherein the optical disc includes a user data area having a plurality of sectors forming a group and a main spare area for defect management of the optical disc, the method comprising the steps of:

during the use of the optical disc, an additional spare area for linear replacement for defect management is allocated at the last of the user data area of the optical disc.

2. The method of claim 1, wherein the additional spare area is allocated to a last section of the user data area and used in a reverse order starting from a last portion of the logical file area.

3. The method of claim 2, wherein the size of the additional spare area is smaller than the last section.

4. The method of claim 1, wherein allocation information on the additional spare area is stored in the defect management area.

5. The method of claim 4, wherein the allocation information of the additional spare area includes start and end position information of the additional spare area.

6. The method according to claim 1, wherein the main spare area is allocated to a spare area for replacing error correction code blocks of less than 16 sectors at a zone boundary due to slipping during disc initialization.

7. The method according to claim 1, wherein the main spare area is allocated for replacing a spare area of error correction code blocks having a sector number less than one block due to slipping replacement during disc initialization at a zone boundary.

8. The method of claim 1, wherein the main spare area is allocated for replacing a spare area of an error correction code block at a sector boundary of a defective block which is not started from a start position of a sector due to slipping replacement of a defective sector.

9. The method according to any one of claims 6 to 8, wherein information about spare areas of the error correction code blocks allocated to the primary spare area is stored in a primary defect table of a defect management area.