Abstract:
A method and device for management of defects in a recording medium such as a DVD disc are disclosed. The present invention utilizes defect processing table to reduce the seek times of a pick-up head in obtaining replacement ECC blocks for defect ECC blocks in a user data area of the disc. The defect processing table is used to indicate a location to access replacement block for a defect block. Since the defect processing table (DPT) stores only the relevant information about the defect block and replacement block rather than the defect block or the replacement block per se, it only needs a very small memory space. The present invention also provides a DPT management unit to manage the contents of the DPT.

Description:
[0001]     This application claims priority to and incorporates by reference the disclosure set forth, in its entirety, in U.S. Provisional Patent Application No. 60/732,844, entitled “DETECT MANAGEMENT METHOD OF USING DEFECT PROCESSING TABLE” filed on Nov. 2, 2005. 
     
    
     TECHNICAL FIELD OF THE INVENTION  
       [0002]     The present application relates to management of defects in a recording medium such as an optical disc, more particularly, to a method for managing defects of the optical disc with a defect processing table, and a disc drive having the defect processing table.  
       BACKGROUND OF THE INVENTION  
       [0003]     Generally, an optical disc  10  (e.g. a DVDRAM disc) is divided into a lead-in area (LIA)  11 , a user data area  13  and a lead-out area (LOA)  15 . In addition, there is a primary spare area (PSA)  17  in front of the user data area  13  and a secondary spare area (SSA)  19  optionally provided in back of the user data area  13 , as shown in  FIG. 1 .  
         [0004]     For a registered defect (e.g. a defect ECC block) in the user data area, a replacement (e.g. a replacement ECC block) is recorded in the spare area. In the example of  FIG. 1 , there are three defect ECC blocks  101 ,  103 ,  105  in the user data area  13 . Replacement ECC blocks  111 ,  113 ,  115  corresponding to the defect ECC blocks  101 ,  103 ,  105  are recorded in the primary spare area  17  as shown.  
         [0005]     When writing the optical disc  10 , a pick-up head writes a first section of the user data area and stops writing when the first defect ECC block  101  is recoreded, this course is indicated as Rec.  1  in  FIG. 1 . Then the pick-up head jumps to write the replacement ECC block  111  to replace the defect ECC block  101 , this course is indicated as Rec.  2 . The pick-up head successively writes a second section of the user data area  13  after the first defect ECC block  101 , and stops writing when the second defect ECC block  103  is recorded, this course is indicated as Rec.  3 . The pick-up head then jumps to write the replacement ECC block  113  to replace the defect ECC block  103 , this course is indicated as Rec.  4 . The pick-up head successively writes a third section of the user data area  13  after the second defect ECC block  103 , and stops writing when the third defect ECC block  105  is recorded, this course is indicated as Rec.  5 . The pick-up head jumps to write the replacement ECC block  115  to replace the defect ECC block  105 , this course is indicated as Rec.  6 .  
         [0006]     As described above and as shown in  FIG. 1 , the pick-up head needs to move back and forth to write the good information in the user data area and the replacement ECC blocks. A method for reducing the number of seek times of the pick-up head is to provide a buffer memory  20 , as shown in  FIG. 2 . In a writing operation, for example, rather than writing the replacement ECC block whenever a defect ECC block is recorded, the write defect ECC block is temporarily stored the buffer memory. After the writing operation is completed, the replacement ECC blocks corresponding to the stored defect ECC blocks are collectively write. However, such a method requires a considerable capacity of memory.  
         [0007]     The present invention provide a solution to overcome the drawbacks mentioned above.  
       SUMMERY OF THE INVENTION  
       [0008]     An objective of the present invention is to provide a method for management of defects in a recording medium such as a DVD disc. The method of the present invention utilizes defect processing table, which occupies a small memory space, to reduce the seek times of a pick-up head in obtaining replacement ECC blocks for defect ECC blocks in a user data area of the disc.  
         [0009]     Another object of the present invention is to provide a defect processing table, which is disposed in a computer readable medium, such as a buffer. The defect processing table is used to indicate a location to access replacement for a defect. For a reading or writing operation, relevant information about all defects found in the user data area and the corresponding replacements is appended into the defect processing table, so that the replacements for the defects can be obtained collectively. Since the defect processing table (DPT) stores only the relevant information about the defects and replacements rather than the defects or the replacements, it only needs a very small memory space. The present invention also provides a DPT management unit to manage the contents of the DPT. The DPT has a plural of items, each of which includes defect related information of one defect. In an embodiment, the DPT has a plurality of rows, and one item is disposed in one row. The defect related information includes information indicating the defect location, information indicating the replacement location, and defect index indicating a location of which the defect is stored in memory.  
         [0010]     A further objective of the present invention is to provide an optical disc drive comprising the computer readable medium with the DPT and the management unit. an apparatus having the DPT and the DPT management unit mentioned above.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     The present invention will be further described in detail in conjunction with the accompanying drawings, wherein:  
         [0012]      FIG. 1  schematically shows a general structure of an optical disc;  
         [0013]      FIG. 2  schematically shows a prior art method for processing defects of the optical disc in  FIG. 1 ;  
         [0014]      FIG. 3  schematically shows a method for process defects of the optical disc in accordance with the present invention;  
         [0015]      FIG. 4  is a block diagram schematically and generally showing a disc drive in accordance with the present invention;  
         [0016]      FIG. 5  is a schematic and general illustration of a defect processing table in accordance with the present invention;  
         [0017]      FIG. 6  schematically shows a structure of an optical disc, in which defect and replacement blocks are processed by the method in accordance with the present invention in a reading operation;  
         [0018]      FIGS. 7A  to  7 E show an embodiment of the defect processing procedure in accordance with the present invention in a reading operation;  
         [0019]      FIG. 8  schematically shows a structure of an optical disc, in which defect and replacement blocks are processed by the method in accordance with the present invention in a writing operation;  
         [0020]      FIGS. 9A  to  9 F show an embodiment of the defect processing procedure in accordance with the present invention in a writing operation; 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]     Referring to  FIGS. 3 and 4 , wherein  FIG. 3  schematically shows a method for process defects of the optical disc in accordance with the present invention, and  FIG. 4  is a block diagram schematically and generally showing a disc drive in accordance with the present invention. In  FIG. 3 , the optical disc structure as shown is the same as that of  FIG. 1  or  FIG. 2 , and the same reference numbers indicates the same portions.  
         [0022]     As shown in  FIGS. 3 and 4 , to manage defects of the optical disc  10  with a quite limited memory capacity, a disc drive in accordance with the present invention has a defect processing table (DPT) buffer  25 , in which a defect process table (DPT) is disposed. The DPT can also disposed in any other computer readable medium. The DPT contains defect related information about a defect rather than the practical content thereof. The details about the DPT will be further described later. The present invention also provides a DPT management unit  30  to manage the DPT stored in the DPT buffer  25 . The DPT buffer  25  and the DPT management unit  30  can be considered together as a defect management device. The DPT management unit  30  may directly access a memory  40  or access the memory  40  via a controller  50 , which is coupled with a host  60  and accesses the optical disc  10 . As currently conventional practice, defects such as defect blocks are stored in the memory  40 . It is noted that the DPT buffer  25  can be implemented by and individual memory or just a portion of the memory  40 .  
         [0023]     In the example of  FIG. 3 , during a first recording operation Rec.  1 , three defect blocks  101 ,  103 ,  105  are found. The defect related information about these three defect blocks are recorded in the DPT of the DPT buffer  25 . The DPT management unit  30  obtains the replacement blocks  111 ,  113 ,  115 , and replaces the defect blocks  101 ,  103 ,  105  with the replacement blocks by accessing the defect blocks and replacement blocks according to the defect related information recorded in the DPT.  
         [0024]      FIG. 5  is a schematic and general illustration of the defect processing table (DPT) in accordance with the present invention. As shown, the DPT has a plurality of rows, n+1 rows in this example. The defect related information for one defect in the optical disc  10 , which is referred to as one item, is appended into one row of the DPT. That is, the defect related information items of defects DT 0  to DTn are respectively recorded in Row  0  to Row n of the DPT. The defect related information at least contains necessary information about the defect. The DPT management unit  30  uses the information recorded in the DPT to process the defect.  
         [0025]     In the present embodiment, the defect related information includes information for indicating a location to access a defect on the optical disc  10 , information for indicating a location to access a replacement for the defect and information for indicating a location to access the defect stored in the memory  40 . Preferably, the information for indicating a location to access a defect on the optical disc  10  is a defect address, such as defect TLSN value in a reading operation or defect PID value is a writing operation; the information for indicating a location to access a replacement for the defect is a replacement address, such as a replacement PID value; and information for indicating a location to access the defect stored in the memory  40  is a defect index indicating the location of the memory  40  where the defect content is stored. In this case, each row of the DPT only requires 8 bytes, wherein three bytes are used to record the defect address, another three bytes are used to record the replacement address and two bytes are used to record the defect index. Therefore, in general, a memory space of hundreds of bytes is sufficient. In comparison, the prior art, in which the defect blocks are stored in the buffer directly, requires a considerably large memory space, since one defect ECC block occupies 32 k bytes for DVD disc in practice.  
         [0026]     In the above description, the addresses of the defects and replacements are recorded in the DPT. However, the form of the information to be recorded in the DPT is not limited to this. For example, the relative relationship between the defects or replacements rather than the addresses thereof can be recorded. Furthermore, additional information can also be recorded into the DPT as desired.  
         [0027]     The processes of the DPT management unit  30  managing the DPT in reading and writing operations for the optical disc  10  will be respectively described.  
         [0028]      FIG. 6  schematically shows a structure of the optical disc  10 , in which defect and replacement blocks are processed by the method in accordance with the present invention in a reading operation. The structure shown in this drawing is substantially the same as that shown in  FIG. 1  or  FIG. 2 . The same reference numbers indicate the same portions in these drawings. After reading the user data area  13  of the optical disc  10  (the period indicated by Buf.  1 ), defect blocks  101 ,  103 ,  105  located at locations with the addresses D 1 , D 2 , D 3  are found, and the replacement blocks  111 ,  113 ,  115  are recorded at the locations in the primary spare area  17  with the addresses R 1 , R 2 , R 3 . The DPT management unit  30  records the addresses of the defect blocks D 1 ,D 2 , D 3 , address of the replacement blocks R 1 , R 2 , R 3  and the defect indices B 1 , B 2 , B 3  of the defect blocks into the DPT. The details will be further described as follows.  
         [0029]      FIGS. 7A  to  7 E show the respective steps of the defect processing procedure in accordance with an embodiment of the present invention in a reading operation. During reading, the DPT management unit  30  uses three pointers to manage the DPT, in which the defect related information such as defect address, replace address and defect index for each defect is stored in a row. The three pointers are defect pointer, replace pointer and process pointer. For reading operation, the defect pointer indicates that a reading of a defect block is finished; the replace pointer indicates that a reading of a replacement block is finished; the process pointer indicates that the transfer of the replacement block is done.  
         [0030]     As shown in  FIG. 7A , after reading the defect blocks  101 ,  103 ,  105 , (Buf.  1  in  FIG. 6 ), the DPT management unit  30  records the addresses of the defect blocks, replacement blocks and the defect indices to the DPT. The defect address D 1  of the first defect block  101 , replacement address R 1  of the replacement block  111  and the defect index B 1  for the first defect block are recorded in the first low, Row  0 , of the DPT. The defect address D 2  of the second defect block  103 , replacement address R 2  of the replacement block  113  and the defect index B 2  for the second defect block are, recorded in Row  1  of the DPT. The defect address D 3  of the third defect block  105 , replacement address R 3  of the replacement block  115  and the defect index B 3  for the third defect block are recorded in Row  2  of the DPT. At this time, since the defect blocks  101 ,  103 ,  105  have been read, the defect pointer points to Row  3  of the DPT. The replace pointer and the process pointer both point to Row  0  of the DPT.  
         [0031]     The sequence of recording the replacement blocks is from outer side to inner side, while the direction of reading is from inner side to outer side. Before reading the replacement blocks, the DPT management unit  30  conducts a sorting to the rows of the DPT according to the reading order for the replacement blocks, that is R 3 , R 2 , R 1 , as shown in  FIG. 7B .  
         [0032]     After the replacement blocks  111 ,  113 ,  115  are read (Buf.  2  period,  FIG. 6 ), the replace pointer points to row  3 , as shown in  FIG. 7C . The replacement blocks  111 ,  113 ,  115  can be read and copied to cover the defect blocks stored in the memory  40  or be read and stored in another memory as desired.  
         [0033]     Before transferring the replacement block data, the DPT management unit  30  conducts another sorting to the rows of the DPT according to order of the defect blocks, that is D 1 , D 2 , D 3 , as shown in  FIG. 7D .  
         [0034]     Whenever data such as the replacement block data for a defect is transferred, the process pointer is added with one. After the three replacement blocks are transferred, the process pointer also points to Row  3 , as shown in  FIG. 7E . The management for the reading operation is finished.  
         [0035]     The management of the DPC management unit  30  for a recording operation will be described with reference to  FIGS. 8 and 9 . During the recording operation, the DPC management unit  30  also uses the three indices, defect pointer, replace pointer and process pointer. However, these indices indicate different meanings as compared to the reading operation. For recording operation, the defect pointer indicates that the writing of a defect block is finished; the replace pointer indicates that the address of the replacement block for the defect block is obtained; the process pointer indicates that the writing of the replacement block is finished.  
         [0036]      FIG. 8  shows a structure of an optical disc  80 , which is similar to that of the optical disc  10  of  FIG. 1 . The like reference numbers indicate the similar portions. As shown, the optical disc  80  has a LIA  81 , a user data area  83 , and a LOA  85 . There are a primary spare area  87  and secondary spare area  89  in front and back of the user data area, respectively. In this example, during the writing operation, an old registered defect block  801  is found at a location with an address D 1 . A replacement block  811  for the defect block  801  is recorded at a location with an address R 1  in the primary spare area  87 . After the writing operation (Rec.  1 ) is finished, a new defect block  802  is found at a location with an address D 2  in verification for the writing operation. The DPT management unit  30  records the defect addresses D 1 , D 2 , the replacement address R 1 , and defect indices B 1 , B 2 , as shown in  FIG. 9A . The defect pointer points to Row  2 . However, the replace pointer points to Row  1 , since an address of a replacement block for the defect block at D 2  has not been obtained. The process pointer points at Row  0 .  
         [0037]     A new replacement block  812  is obtained for the defect block  802  found during the verification. The replacement block  812  is recorded at a location with an address R 2  as shown in  FIG. 8 . The DPT management unit  30  obtains the address R 2  of the replacement block  812  and fills it into the DPT, as shown in  FIG. 9B . Now the replace pointer also points to Row  2 .  
         [0038]     Similar to the reading operation, before recording the replacement blocks, the sequence of the rows of the DPT is sorted according to the order that the replacement blocks to be recorded, that is, R 2  to R 1 , as shown in  FIG. 9C . The recording of the replacement blocks  811 ,  812  (Rec.  2 ,  FIG. 8 ) is that the DPT management unit  30  obtains the original data to be recorded in the defect blocks  801 ,  802  according to the defect indices B 1 , B 2  and directly writes the original data to the replacement blocks  811 ,  812 . It does not need an additional buffer memory to store the original data.  
         [0039]     After the replacement blocks  811 ,  812  are recorded, the process pointer points to Row  2 , a verification is executed. If it is found that replacement block  812  at the address R 2  is defective, the DPT management unit  30  fills the original defect address D 2  of R 2 , and the corresponding defect index B 2  at a new row (Row  2  in this example) of the DPT, as shown in  FIG. 9D . The defect pointer points to Row  3 . The replace pointer and the process pointer maintain at Row  2 .  
         [0040]     The DPT management unit  30  repeats the step described with  FIG. 9B  to obtain an address R 3  of a new replacement block  822 , and fills the address R 3  into Row  2  of the DPT, as shown in  FIG. 9E . At this time, the replace pointer also points to Row  3 .  
         [0041]     If the replacement block  822  is also defective, the DPT management unit  30  will repeats the steps described above to get an address R 4  of a new replacement block  832 . As shown in  FIG. 9F , the defect related information including the defect block D 2 , the replacement block address R 4  and the defect index B 2  is recorded in Row  3  of the DPT. As above, a verification is executed. It there is no additional defective block found, the writing of the replacement blocks is done, and all of the three indices used by the DPT management unit  30  point to the same row, Row  4  in the present embodiment, as shown in  FIG. 9F .  
         [0042]     As described above, either in the reading or recording operation, when the three pointers of the DPT management unit  30  points to the same row of the DPT, the process of the operation is completed.  
         [0043]     While the preferred embodiments of the present invention have been illustrated and described in detail, various modifications and alterations can be made by persons skilled in this art. The embodiment of the present invention is therefore described in an illustrative but not restrictive sense. It is intended that the present invention should not be limited to the particular forms as illustrated, and that all modifications and alterations which maintain the spirit and realm of the present invention are within the scope as defined in the appended claims.