Abstract:
A write processing method and an optical disc drive, whereby the control technology for recording information avoids defects on a recording surface of the optical disc during recording.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention generally relates to a write processing method and an optical disc drive, whereby the control technology records information while avoiding defects on a recording surface of the optical disc.  
         [0003]     2. Description of the Background Art  
         [0004]     In a writable optical disc, when there was a defect area having a size greater than a recording operation guarantee in the recording surface of an optical disc, an optical disc drive cannot perform servo control. As a result, the optical disc drive fails to record information to the optical disc.  
         [0005]     For a write once type of optical disc, where it is possible to record information once on the disc, the optical disc drive does not perform a retry process. Instead, the drive performs post processing to be only accessible for a previously recorded area (i.e., a write enabled area)  20  as illustrated in  FIG. 6 . For this reason, an area “ahead” of the recordable area (i.e., a write disabled area)  23  was not able to be used due to the defect area  22  in the optical disc  21 .  
         [0006]     For rewritable optical discs, which record using phase change technology, when a record error occurs in a defect area, the optical disc drive performs re-try processing at the sector address where the error occurred.  
         [0007]     In addition, as described in Japanese Laid-Open Patent Application No. 9-270175, the defect area on the optical disc is detected. When the defect is detected, the optical disc drive outputs that fact (i.e., error occurred) to a host device. Furthermore, it is suggested that the problem with the defect area is solved by recording dummy data.  
         [0008]     In the background art, for write once optical discs, when a record error occurs due to a defect area, if there is a writable area beyond the defect area, the optical disc drive cannot continue writing to the writable area beyond the defect area.  
         [0009]     In addition, for example, when a television broadcast is received and is recorded as a video picture to the optical disc, a continuousness of the video picture data becomes important in order to guarantee reliability of the recorded data. However, when using the rewritable optical disc, if the retry process is performed when the recording error due to the defect area occurs, there will be an omission of time from the broadcast data caused by the retry process, which is undesirable.  
       SUMMARY OF THE INVENTION  
       [0010]     The object of the present invention solves the afore-mentioned problems of the background art. When a recording error occurs due to a defect area on the disc, if it is a situation where data is input continuously, an omission of time in the recorded data is substantially prevented by a concise technique.  
         [0011]     Another object of the present invention is to provide a record processing method, an optical disc drive and a recording medium for an optical disc making it possible to continue a recording operation beyond a defect area. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     A more complete appreciation of the present invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a block diagram of an optical disc drive according to the present invention;  
         [0014]      FIG. 2  is a flow chart of recording process according to a first embodiment of the present invention;  
         [0015]      FIG. 3  is a flow chart of recording process according to a second embodiment of the present invention;  
         [0016]      FIG. 4  is a flow chart of specific example for steps of servo recovering process according to a second embodiment of the present invention;  
         [0017]      FIG. 5  illustrates an optical disc after data is recorded beyond the defect area in the optical disc according to an embodiment of the present invention; and  
         [0018]      FIG. 6  illustrates an optical disc having a defect area according to the background art. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]     A description will now be given, with reference to drawings of embodiments of the present invention in which like reference numerals indicate identical or corresponding parts throughout the several views.  
         [0020]      FIG. 1  is a block diagram of an optical disc drive according to the present invention. The optical disc drive as an embodiment of the present invention includes a spindle motor  2  that rotates an optical disc  1  such as e.g., CD, CD-R, CD-RW, DVD, DVD+R, DVD+RW, DVD−R, and DVD−RW discs, an optical pickup  4  having a semiconductor laser that applies a laser beam to a recording region of the optical disc  1  and also having an electromagnetic servo unit  5  to drive an object lens in a focusing direction and a tracking direction, and a seek motor  6  that actuates the optical pickup  4  in the radial direction of the optical disc  1 .  
         [0021]     The optical disc drive shown in  FIG. 1  is further provided with a rotation control unit  3  that controls the rotation of the motor  2 , a seek motor control unit  8  that activates the seek motor  6 , an optical pickup control unit  7  that controls the optical pickup  4 , and a signal processing unit  9  that processes a signal read by the optical pickup  4  from the recording region of the optical disc  1  and a signal to be written by the optical pickup  4  in the recording region of the optical disc  1 . In addition, the signal processing unit  9  generates signals for example, an RF signal, a focusing control signal or a tracking control signal.  
         [0022]     The optical disc drive shown in  FIG. 1  is further provided with a buffer memory  112  that temporarily stores data read from the optical disc  1 , and a controller  160  consisting of electronic components such as a CPU and a RAM, that perform various processing in connection with the present invention as well as the controlling of the other control units  3 ,  7 , and  8  and the signal processing unit  9 . The controller  10  is connected with a host computer  11  through an external interface so that the controller  10  transmits user data read from the optical disc  1  to the host computer  11  in response to a request from the host computer  11  and receives user data to be written to the optical disc  1  from the host computer  11 . A flash ROM memory  13  includes control programs used by the controller  10 .  
         [0023]     In a communication between the optical drive and the host computer  11 , the optical disc drive receives a command from the host computer  11  and sends a response for the command to the host computer  11 . If necessary, data is also received or sent between the optical drive and the host computer  11 . In addition, it is possible that the optical drive is updated with a control program by the host computer  11 .  
         [0024]      FIG. 2  is a flowchart of a recording process according to a first embodiment of the present invention. The optical disc drive receives a write start command and data for writing from the host computer  11  through the host interface (step S 1 - 1 ). The received data is stored temporary to the buffer memory  12  (S 1 - 2 ). When the amount of the received data in the buffer memory  12  reaches a predetermined amount (“Yes” at step S 1 - 3 ), a write process to the optical disc  1  is started as shown in step S 1 - 4 . While information is being written to the disc, the optical disc drive sends a response for the received write command to the host computer  11 . The response indicates that the write process is finished normally. The optical disc drive writes the data to the optical disc normally and continuously (“No” of step S 1 - 5 ), and after the optical disc drive writes all data to the optical disc (step S 1 - 6 ), the writing process is completed.  
         [0025]     After the writing process started, if there is a defect area on a recording surface of the optical disc  1 , a write error has occurred (step S 1 - 5 ) with a servo error on the focusing servo control or the tracking servo control. For this problem, the controller  10  detects a reduced amount of reflection light of the laser beam emitted from the optical pickup  4  at the optical disc  1 . If the amount of reflection light is reduced by a predetermined amount, the optical disc drive will stop the writing process.  
         [0026]     The controller  10  generates NWA (Next Writable Address) after the error is detected. More specifically, the controller  10  generates an address (NWA) by adding a predetermined address (i.e., offset) for the sector address where the error occurred (step S 1 - 7 ). The optical disc drive reports the error with the NWA to the host computer  11  (step S 1 - 8 ).  
         [0027]     When the host computer  11  sends the next write command and data for writing after the error is detected (“No” of step S 1 - 9 ), the controller  10  makes the seek motor controlling unit  8  drive the seek motor  6  to move the optical pickup  4  to the NWA (step S 1 - 10 ). The controller  10  performs error detection processing at least one rotation from this address. In addition, the controller  10  performs servo recovery for a predetermined number of times until the servo status becomes stable.  
         [0028]     If there is no error during the above described process (“No” of step S 1 - 11 ), the writing process completes after writing a sector address, where the error occurred, and a sector address, which is a starting address for writing correctly after the error occurred, to a management data writing area allocated in the optical disc  1  (step S 1 - 12 ). According to the process of the present invention, it becomes possible to write continuously over (i.e., beyond) the defect area on the disc.  
         [0029]      FIG. 5  illustrates an optical disc  1  after data is recorded by skipping over the defect area  22  in the optical disc  1  according to an embodiment of the present invention. A circumferential area including the defect area  22  becomes a write disabled area  24 . It is possible, however, that an inner area and an outer area of the circumferential area surrounding the defect area  22  becomes a write enabled area  23 . Since the management data writing error  25  includes the sector address where the error occurred and the sector address for the starting address to write correctly after the error occurred, it is possible to retrieve written data from the write enabled area  23  allocated with the inner area and the outer area of the circumferential area including the defect area  22 .  
         [0030]      FIG. 3  is a flowchart of a recording process according to a second embodiment of the present invention.  FIG. 4  is a flowchart of a specific example for the steps performed in a servo recovering process according to the second embodiment of the present invention.  
         [0031]     According to the writing process of  FIG. 3 , the optical disc drive receives a write command and data for writing from host computer  11  through the host interface (step S 2 - 1 ). The received data is stored temporary to the buffer memory  12  (step S 2 - 2 ). When the amount of the received data in the buffer memory  12  reaches a predetermined amount (“Yes” at step S 2 - 3 ), the data stored in the buffer memory  12  is written to the disc (step S 2 - 4 ).  
         [0032]     The optical disc drive writes the data to the optical disc normally and continuously (“No” at step S 2 - 5 ), and after the optical disc drive writes all data to the optical disc, the writing process is completed and the optical disc drive send response to the host computer (step S 2 - 6 ). If, however, the controller  10  finds the defect area on the recording surface on the optical disc  1  (“Yes” at step S 2 - 5 ), the optical disc drive sends a response to the host computer  11  indicating a completion of the data writing (step S 2 - 7 ). After the writing process started, if there is a defect area on a recording surface of the optical disc  1 , a write error has occurred with either a servo error on the focusing servo control or the tracking servo control. For this problem, the controller  10  detects a reduced amount of reflection light of the laser beam emitted from the optical pickup  4  at the optical disc  1 . If the error is detected, the controller  10  does servo recovery processing (step S 2 - 8 ) an example of which is shown in  FIG. 4 .  
         [0033]     As shown in  FIG.4 , in the servo recovery process, the controller  10  makes the seek motor controlling unit  8  drive the seek motor  6  to move the optical pickup  4  to a home position and start servo control. After the servo process becomes stable (“Yes” at step S 2 - 9 ), the controller  10  makes the seek motor controlling unit  8  drive the seek motor  6  to move the optical pickup  4  to an address including the last received command (step S 2 - 10 ), and the controller  10  performs servo recovery until the seek status becomes stable (“Yes” at step S 2 - 11 ).  
         [0034]     In this case, the data received from the host computer  11  is not written to the optical disc  1  and is discarded; the optical disc drive skips addresses from where the error occurred until the servo status becomes stable (step S 2 - 12 ).  
         [0035]     After the servo recovers, the writing process writes a sector address where the error occurred and a sector address which serves as a starting address for writing correctly after the error occurred to a management data writing area allocated on the optical disc  1  (S 2 - 13 ). The process continues at step S 2 - 1 , where the writing process writes the next data received from the host computer  11  continuously over/beyond the defect area.  
         [0036]     As above described, when the optical disc drive detects the defect area, the optical disc drive skips writing data received while the error is occurring, but the optical disc sends a “no error” response to the host computer  11 . This way, the host computer  11  sends the write command and the write data continuously. However, if the address of last received data and the address of currently received data are not continuous, the last received data and currently received data are not continuous, and so the optical disc drive does not skip the writing.  
         [0037]     This application claims priority to Japanese Patent Application No. 2004-150329, filed May 20, 2004, which is herby incorporated by reference herein.  
         [0038]     The processes and devices described above illustrate preferred methods and typical devices of many that could be used and produced. The above description and drawings illustrate embodiments, which achieve the objects, features, and advantages of the present invention. However, it is not intended that the present invention be strictly limited to the above-described and illustrated embodiments. Any modification, though presently unforeseeable, of the present invention that comes within the spirit and scope of the following claims should be considered part of the present invention.