Abstract:
A defect management method applied in an optical disc drive for managing defect information of an optical disc is disclosed. The optical disc drive saves a plurality of defect tables comprising at least a first defect table and a second defect table. The first defect table records a plurality of first defect entries and the second defect table records a plurality of second defect entries. The method includes appending an adaptive defect entry comprising a new defect information corresponding to a new defect into a new defect table, a data structure of the adaptive defect entry conforming to a data structure of at least one of the defect entries recorded in the defect tables; and merging the adaptive defect entries into one of the defect tables saved in the optical disc drive when a condition is met.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This is a continuation in part of U.S. application Ser. No. 10/065,768 that was filed on Nov. 18, 2002 now U.S. Pat. No. 7,050,369 and is included herein by reference. 

   BACKGROUND 
   1. Technical Field 
   The present invention relates to an optical disc drive and method of managing and storing addresses of defective data blocks on an optical disc, and more particularly, to an optical disc drive and method of managing and storing addresses of defective data blocks on an optical disc which creates a new defect table in the memory. 
   2. Description of the Prior Art 
   Optical discs, given their compact size, high capacity storage, and low price, have rapidly become one of the most dominant, non-volatile storage media in the contemporary information society. For example, the development of a DVD-RAM has made it possible for users to write data onto optical discs in accordance with their own specific needs, which affords the DVD-RAM a high degree of application flexibility. 
   It is necessary to have an optical disc drive before reading and writing data onto an optical disc. Please refer to  FIG. 1  that shows a conventional optical disc drive  10 . The optical disc drive  10  comprises a holder plate  14  to carry an optical disc  22 , a motor  12  that drives the holder plate  14 , a read/write head  16  that accesses data on the optical disc  22 , a control circuit  18  that controls the operation of the optical disc drive  10 , and a memory  20 , such as Dynamic Random Access Memory (DRAM), that serves as a temporary storage device to record all relevant data during the operation of the control circuit  18 . 
   The data on the optical disc  22  is recorded sequentially onto a track  24  through pit and land markings. It should be noted that for different kinds of optical discs, the schemes of recording the pit and land markings are different. Taking the DVD-RAM disc for example, a phase change technique is adopted to record pits and lands. In other words, data recording scheme applied to the DVD-RAM disc is similar to that applied to the CD-RW disc. When the optical disc drive  10  is ready to write data onto the optical disc  22 , first the optical disc drive  10  stores the intended data in the memory  20  before writing the intended data onto the optical disc  22 . The pick-up head  16  meanwhile checks for defects in the optical disc  22 , and passes the check results back to control circuit  18 . 
   Often due to defects stemming from scratch marks, change of material properties, or interference by micro-dust, data cannot be written onto the optical disc  22 . To improve the reliability of an optical disc (e.g., a DVD-RAM disc), the information technology industry has committed itself to research and development optical disc defect management. When certain areas of the optical disc contain a defect that renders that area unsuitable for data storage, the DVD-RAM format redirects the target data for storage to a usable area. 
   When the optical disc drive  10  tries to access data on the optical disc  22 , it temporarily loads the created defect table of the optical disc  22  into the memory  20 . DT is hereinafter used to refer to the defect table of the optical disc  22  and as is well known the DVD-RAM optical disc contains two DTs that will be described in detail later. When the optical disc drive  10  tries to access data on the optical disc  22 , the optical disc drive  10  uses the address of each data block to access the data it desires. If a data block is defective, the optical disc drive  10  then enlists the help of the DT to locate the replacement data block that stores the user data. In this manner, even with defects on the optical disc  22 , the optical disc  22  still can store data for read-out. 
   On the other hand, the optical disc drive  10  writing data onto the optical disc  22  requires updating the DT in temporary storage in memory  20  accordingly. For instance, assume that during the write-in the optical disc drive  10  discovers a new defect on the optical disc  22  during a formatting stage or a writing data stage. The optical disc drive  10  directly inserts an entry corresponding to the new defect into the DT buffered in the memory  20  in defective address order (i.e., based on the address of the defect). The details of this operation are well known to those of average skill in this art and are therefore omitted herein for the sake of brevity. Later, when the optical disc drive  10  stops accessing data on the optical disc  22  the optical disc drive  10  writes the updated DT from the memory  20  onto the optical disc  22 . For example, the optical disc drive  10  will stop access data on the optical disc  22  when the optical disc  22  is ejected at the conclusion of the formatting stage or the writing stage. This updated DT provides the reference that the optical disc drive  10  needs when it tries to access data on the optical disc  22  the next time around. 
   Please refer to  FIG. 2  in conjunction with  FIG. 3 .  FIG. 2  is a diagram illustrating a primary defect list (PDL) table  26  of the optical disc  20  according to the related art, and  FIG. 3  is a diagram illustrating a secondary defect list (SDL) table  28  of the optical disc  20  according to the related art. Notice that for DVD-RAM disc the entries of the PDL table  26  are each four bytes that are composed of the following information and in parentheses the corresponding size required to store that information: PDL type (1 byte) and defective address (3 bytes). Also, notice that in the SDL table  28  the entries are each eight bytes that are composed of the following information and in parentheses the corresponding size required to store that information: SDL type (1 byte), defective address (3 bytes), reserve byte (1 byte), and replacement address (3 bytes). Regardless of their locations, the entries of the PDL table  26  and the SDL table  28  are sorted according to the addresses of the defective data blocks with which they correspond. For example, the defective data blocks can be sorted in an ascending order such as PDL entry 0&lt;PDL entry 1&lt;PDL entry 2&lt;PDL entry P&lt;FFFFFFFF. Please note that FFFFFFFF indicates the end of the PDL table  26 . However, there may not exist any specific order among the corresponding addresses of the data blocks that are utilized in place of defective data blocks. In general, the PDL table  26  is used for recording defect entries during the formatting stage, while the SDL table  28  is used for recording defects during the data writing stage. 
   As mentioned earlier, if the optical disc drive  10  uncovers a defective data block during the write-in stage, the optical disc drive  10  replaces the defective data block with another data block (e.g., an available spare block) and updates the SDL table  28  that is temporarily stored in the memory  20  so that the updated SDL table  28  reflects the latest linkage between the defective blocks and the replacement data blocks. 
   It is apparent that this related art defect management method is inefficient as it results in unnecessary modifications to the PDL table  26  or the SDL table  28  in the memory  20  and the frequently executed sort operation will degrade performance of the memory  20 . Therefore, it is apparent that new and improved methods and devices are needed. 
   SUMMARY 
   According to one aspect of the claimed invention, a defect management method applied in an optical disc drive for managing defect information of an optical disc is disclosed. The optical disc drive saves a plurality of defect tables comprising at least a first defect table and a second defect table, the first defect table records a plurality of first defect entries and the second defect table records a plurality of second defect entries, the method includes appending an adaptive defect entry comprising a new defect information corresponding to a new defect into a new defect table, a data structure of the adaptive defect entry conforming to a data structure of at least one of the defect entries recorded in the defect tables, and merging the adaptive defect entries into one of the defect tables saved in the optical disc drive when a condition is met. 
   According to another aspect of the claimed invention, a defect management system applied in an optical disc drive for managing defect information of an optical disc is disclosed. The system includes a pick-up head, a memory, and a controller. The memory saves a plurality of defect tables comprising at least a first defect table and a second defect table, the first defect table recording a plurality of first defect entries, the second defect table recording a plurality of second defect entries, and saving a new defect table for recording a plurality of adaptive defect entries corresponding to a plurality of new defect information, a data structure of the adaptive defect entries conforming to a data structure of at least one of the defect entries recorded in one of the defect tables. The controller, coupled to the pick-up head and the memory, controls the pick-up head to access the first and second defect tables from the optical disc and store the defect tables into the memory, appends a new defect entry into the new defect table until meeting a condition, and merges the adaptive defect entries into one of the defect tables saved in the optical disc drive when a condition is met. 
   The number of times the entries are sorted in the PDL table or the SDL table is reduced in the present disclosure. This is achieved by using the new defect list (NDL) table to buffer the adaptive defect entries of the new defective data blocks on the optical disc. In addition, when a merging operation is actuated, the NDL table to be merged with the PDL table or the SDL table already has adaptive defect entries stored in defective address order. In this way the merging operations is simplified. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram of a conventional optical disc drive. 
       FIG. 2  is a diagram illustrating a primary defect list (PDL) table of an optical disc according to the related art. 
       FIG. 3  is a diagram illustrating a secondary defect list (SDL) table of an optical disc according to the related art. 
       FIG. 4  is a diagram illustrating an optical disc drive according to an embodiment of the present invention. 
       FIG. 5  is a diagram illustrating a new defect list (NDL) table according to an embodiment of the present invention. 
       FIG. 6  is a flow chart illustrating a method of managing data on an optical disc according to an embodiment of the present invention. 
       FIG. 7  is a diagram illustrating the NDL table being merged with the PDL table or the SDL table according to an embodiment of the present invention. 
       FIG. 8  is a diagram illustrating an adaptive defect entry being appended to the empty NDL table after the merging operation is completed according to an embodiment of the present invention. 
       FIG. 9  is a diagram showing a new adaptive defect entry being directly appended to the NDL table according to an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, consumer electronic equipment manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ” The terms “couple” and “couples” are intended to mean either an indirect or a direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections. 
   Please refer to  FIG. 4 .  FIG. 4  is a diagram illustrating an optical disc drive  100  according to an embodiment of the present invention. As shown in  FIG. 4 , the optical disc drive  100  includes a pick-up head  104  for accessing an optical disc  102  (e.g., a DVD-RAM disc), a controller  106  for controlling operation of the optical disc drive  100 , and a memory (e.g., a DRAM) for buffering data such as the afore-mentioned PDL table  26  and SDL table  28 . In this embodiment, after the optical disc drive  100  is powered on, the controller  106  will create a new defect list (NDL) table  30  in the memory  108 . Please refer to  FIG. 5 .  FIG. 5  is a diagram illustrating the NDL table  30  shown in  FIG. 4 . Please note that  FIG. 5  is shown being possible either PDL or SDL compatible and this is indicated by the “PDL/SDL” notation in the adaptive defect entries of the NDL table  30 . The NDL table  30  is created in the memory  108  of the optical disc drive  100  for storing adaptive defect entries of newly identified defects on the optical disc  102 . The NDL table  30 , in this embodiment, is created according to one of two stages of the optical disc drive  100 . First, during a formatting stage the NDL table  30  complies with the four byte address size of the PDL table  26  of  FIG. 2 . During a data writing stage the NDL table  30  complies with the SDL table  28  of  FIG. 2 . Additionally, the NDL table  30  is created based on said stages but also according to the utilized capacity status of the defect table set, either the PDL table  26  or the SDL table  28 . Specifically, during the formatting stage the PDL table  26  may become full, thereby causing the NDL table  30  to consist of adaptive defect entries that are compatible with the eight byte SDL defect entries to store the over flow because the PDL table  26  can store entries no more. 
   Please refer to  FIG. 6 .  FIG. 6  is a flow chart illustrating the method of managing data on the optical disc according to an embodiment of the present invention. The method of the present invention comprises the following steps: 
   Step  400 : Start. 
   Step  405 : Is stage writing? If yes, go to step  420 . 
   Step  410 : Is PDL full? If no, go to step  425 . 
   Step  420 : Create NDL table compatible with SDL table and go to step  430 . 
   Step  425 : Create NDL table compatible with PDL table. 
   Step  430 : New defect is detected. 
   Step  435 : Is address of most recent adaptive defect entry in NDL table smaller than the address of new defect? If yes, go to step  445 . 
   Step  440 : Merge the NDL table with the PDL table/SDL table. 
   Step  445 : Appended new defect to the NDL table. 
   Step  450 : Merge NDL table with PDL table/SDL table before exiting formatting or writing stage. 
   Step  455 : Stop. 
   In step  400 , the flow beings. In the beginning, the PDL table  26  and SDL table  28  stored on the optical disc  102  are read by the pick-up head  104 , and then buffered into the memory  108 . In step  405  it is determined if the adaptive defect entries of the NDL table  30  must be compatible with SDL type defect entries based on the disc operation mode of the optical disc drive  100 . If the disc operation mode is a data writing stage, then in step  420  the NDL table  30  is created by the controller  106  to be compatible with the SDL table  28  otherwise in step  410 , it is known that the disc operation mode or stage of the optical disc drive  100  is for disc formatting and it is determined if the utilized capacity status of the PDL table  26  is full. If yes, then the controller  106  creates the NDL table  30  having a data structure identical to a data structure of the SDL table  28  in step  420  or conversely, if not, then in step  425  the controller  106  creates the NDL table  30  having a data structure identical to a data structure of the PDL table  26  because it is known that the disc operation mode or stage of the optical disc drive  100  is for disc formatting and the utilized capacity status of the PDL table  26  is not full. 
   In step  430 , a new defect on the optical disc  102  is detected by any well-known means utilized by the optical disc drive  100 . In step  435 , the controller  106  must determine if the address of the most recent adaptive defect entry recorded in the NDL table  30  contains an address of a defective data block smaller than the address of the newly detected defective data block or not. If no, then in step  440  the NDL table  30  is merged with the PDL table or the SDL table depending on the stage being formatting or writing. Please refer to  FIG. 7  and  FIG. 8 .  FIG. 7  is a diagram illustrating the NDL table  30  being merged with the PDL table  26  or the SDL table  28  according to an embodiment of the present invention.  FIG. 8  is a diagram illustrating a new adaptive defect entry being appended to the empty NDL table  30  after the merging operation is completed. As shown in  FIG. 7 , the new adaptive defect entry n (x−M) records an address for the newly detected defective data block smaller than the address contained in the last entry n x stored in the NDL table  30 . Therefore, a merging operation is actuated. After the merging operation of step  440  is completed, the NDL table  30  becomes empty and the flow continues to step  445 . As shown in  FIG. 8 , the new adaptive defect entry n (x−M) is appended to the empty NDL table  30  and then becomes the first adaptive defect entry in the NDL table  30 . Please note, for simplification the NDL table  30  in  FIG. 7  is shown being possible either PDL or SDL compatible and this is indicated by the “PDL/SDL” notation in the adaptive defect entries of the NDL table  30 . 
   Please refer again to  FIG. 6 . Rather than the scenario just described, if in step  435  it is determined that the address of the most recent adaptive defect entry recorded in the NDL table  30  contains an address of a defective data block smaller than the address of the newly detected defective data block then the new adaptive defect entry is directly appended to the NDL table  30  in step  445 . Please refer to  FIG. 9 .  FIG. 9  is a diagram showing the new adaptive defect entry being directly appended to the NDL table  30 . As shown in  FIG. 9 , the new adaptive defect entry n (x+M) records an address for the newly detected defective data block greater than the address contained in the last adaptive defect entry n x stored in the NDL table  30 . Therefore, the new adaptive defect entry n (x+M) is directly appended to the NDL table  30  and no merging operation is needed. Please note that the NDL table  30  in  FIG. 9  is shown being possible either PDL or SDL compatible and this is indicated by the “PDL/SDL” notation in the adaptive defect entries of the NDL table  30 . 
   Finally, in step  450 , all adaptive defect entries existing in the NDL table  30  are merged with either the PDL table  26  or the SDL table  28  in the memory  108  before exiting the disc operation mode, either disc formatting stage or data writing stage. As mentioned above, before the optical disc  102  is ejected, the PDL table  26  and the SDL table  28  in the memory  108  are written back to the optical disc  102 . 
   Please note, that in the above embodiment, the NDL table  30  can be merged with either the PDL table  26  or the SDL table  28  in the memory  108  based on a number of conditions. For example, one such condition can be after a predetermined time period. For example, for reliability, the present invention can perform the merging operation from time to time. Additionally, the condition for merging can be when any operation of the optical disc drive has been performed. These conditions are by way of example and not a limitation of the present invention. Additional conditions can be utilized and are well-known to those of average skill in this art and are therefore omitted here. 
   Please note, that in the above embodiment, the detailed defect table management scheme is applied to a DVD-RAM disc. However, this is only meant to be an example, and is not meant to be taken as a limitation of the present invention. 
   In contrast to the related art, the number of times of sorting the entries in the PDL table or the SDL table is reduced by using the NDL table to buffer the adaptive defect entries of the new defective data blocks on the optical disc. In addition, when a merging operation is actuated, the NDL table to be merged with the PDL table or the SDL table have adaptive defect entries stored in adaptive defect entry address order already, which simplifies the merging operation. 
   Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above invention should be construed as limited only by the metes and bounds of the appended claims.