Abstract:
A method for recording data on an optical disc, includes detecting optimum writing power from a test area on the optical disc; determining whether or not a current writing power is within a predetermined allowable range set with reference to the detected optimum writing power; and performing a writing operation with the writing power controlled to maintain a reflection signal level corresponding to the detected optimum writing power when the current writing power is within the predetermined allowable range, and performing the writing operation with the writing power controlled based on power update information when the current writing power is not within the predetermined allowable range.

Description:
[0001]    This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 03-13520 filed in Korea on Mar. 4, 2003, which is herein incorporated by reference.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to an apparatus and method for controlling the writing power of an optical disc and more particularly to an apparatus and method for controlling the writing power of an optical disc that takes into consideration a material characteristic deviation between the inner and outer peripheral portions of the optical disc, so as to write data on the optical disc in an optimal state.  
           [0004]    2. Description of the Related Art  
           [0005]    [0005]FIG. 1 illustrates a configuration of a related art optical disc recording/reproducing apparatus. As shown in FIG. 1, the related art recording/reproducing apparatus includes a digital write signal processor  30   a  which adds an error correction code (ECC) to input digital data, thereby converting the input digital data to have a desired writing format. A channel bit (CB) encoder  40  re-converts the data, previously converted by the digital write signal processor  30   a  to have the desired writing format, into a write signal in the form of a bit stream. An optic drive  41  outputs a drive signal with a light amount controlled in accordance with a control signal applied thereto. An optical pickup  20  writes the bit stream on an optical disc  10  in accordance with the drive signal, and detects a signal written on the optical disc  10  in the form of a radio frequency (RF) signal. The optical disc  10  may be a recordable compact disc (CD-R), for example.  
           [0006]    The recording/reproducing apparatus also includes an RF processor  50  which filters and shapes the RF signal detected by the optical pickup  20  to output a binary signal. A first level detector, indicated as “Level Detector  1 ,”  51  detects the level (B-level) of a signal reflected from a mark area on the optical disc  10  in a writing operation. A second level detector  52 , indicated as “Level Detector  2 ”, detects the level (RF-level) of the RF signal outputted from the R/F processor  50 . A wobble signal detector  53  detects a wobble signal from the reflection signal outputted from the optical pickup  20 . An absolute time in pre-groove (ATIP) decoder  54  decodes the wobble signal at the point in time when a particular reproduction pulse duration (for example, 5T) is detected, thereby detecting ATIP data.  
           [0007]    The recording/reproducing apparatus further includes a drive unit  60  for driving the optical pickup  20  and a spindle motor  11 . A servo unit controls the drive unit  60  in accordance with servo signals. The servo signals include a focusing error (FE) signal and a tracking error (TE) signal. A digital reproduction signal processor  30   b  recovers the binary signal using a clock phase-synchronized with the binary signal. A microcomputer  70  controls a recording/reproducing operation for the optical disc  10 , and also controls the level of writing power in the writing operation.  
           [0008]    The microcomputer  70  includes an internal ROM  71  stored with information about optimal write strategies corresponding to respective disc codes for various disc types.  
           [0009]    [0009]FIGS. 2 a  and  2   b  are flow charts illustrating a related art data recording method carried out in the general optical disc recording/reproducing apparatus of FIG. 1. The recording method of FIGS. 2 a  and  2   b  is described hereinafter with reference to the configuration of FIG. 1.  
           [0010]    When the optical disc  10  is loaded into the recording/reproducing apparatus and subsequently rotated, the optical pickup  20  detects a reflection signal generated as a main beam which is reflected from the optical disc  10 . The optical pickup  20  outputs the detected reflection signal to the wobble signal detector  53 . The wobble signal detector  53 , in turn, detects a wobble signal from the reflection signal. On the other hand, the ATIP decoder  54  samples and decodes the wobble signal at the point in time when a particular reproduction pulse duration is detected, thereby detecting ATIP data. Even when the wobble signal corresponding to a short reproduction pulse duration is sampled, ATIP data can be detected because the ATIP data is low-frequency-modulated data.  
           [0011]    The microcomputer  70  detects a disc code from the detected ATIP data, and identifies, in the internal ROM  71 , an optimal write strategy corresponding to the detected disc code in step S 1  of FIG. 2 a.    
           [0012]    If a writing operation is subsequently requested in step S 2 , the microcomputer  70  performs an optimal power calibration (OPC) operation which detects an optimal writing power at a test area on the inner peripheral portion of the optical disc  10  in step S 3 . The microcomputer  70  stores the detected optimal writing power and an optimal reflection signal level (B-level) corresponding to the detected optimal writing power.  
           [0013]    Thereafter, the microcomputer  70  performs a writing operation at a data area on the optical disc  10  by applying the detected optimal writing power and the identified optimal write strategy in step S 4 . In the writing operation, the first level detector  51  detects the level of a signal caused by reflection of a write beam, that is, the level of a reflection signal, or the B-level, reflected from the mark area. The second level detector  52  detects the level of an RF signal output from the RF processor  50 . At this time, the first level detector  51  detects the B-level of the reflection signal at the point in time when a variation in characteristics of the optical disc medium caused by the write beam is stabilized, for example, at a reproduction pulse duration of 11T.  
           [0014]    The microcomputer  70  determines whether or not a running OPC (ROPC) operation is to be carried out, based on the detected B-level and RF signal level in step S 5 . If it is determined that it is unnecessary to carry out the ROPC operation in step S 6 , the microcomputer  70  performs a writing operation while maintaining the optimal writing power detected in accordance with the OPC operation, without performing any ROPC operation in steps S 7  and S 8 .  
           [0015]    [0015]FIG. 3 depicts a variation in writing power depending on a material characteristic deviation between the inner and outer peripheral portions of an optical disc. Where the optical disc  10  has little material characteristic deviation between its inner and outer peripheral portions, which is indicated as “A” in FIG. 3, it is possible to obtain a desired RF signal level and a desired jitter quality at both the inner and outer peripheral portions of the optical disc  10  even when writing of data is carried out under a condition in which the detected optimal writing power is maintained, without execution of any ROPC operation.  
           [0016]    If it is determined in step S 5  that it is necessary to carry out an ROPC operation, the microcomputer  70  performs the ROPC. operation until the writing operation is completed in steps S 9  and S 12 . If writing of data is carried out under a condition in which the detected optimal writing power is maintained, and where the optical disc  10  has a substantial material characteristic deviation between its inner and outer peripheral portions, which is indicated as “B” or “B′” in FIG. 3, it is impossible to obtain a desired RF signal level and a desired jitter quality. Thus, a degradation in reproduction characteristics occurs. In order to avoid such a problem, therefore, the microcomputer  70  performs the ROPC operation, based on the detected levels.  
           [0017]    The ROPC operation is adapted to continuously adjust the writing power, based on the B-level at the point in time when a variation in characteristics of the optical disc medium caused by the write beam in a writing operation is stabilized, such that the writing power is equal to the detected and stored level of the reflection signal generated at the test area. Since the ROPC operation is effective within an allowable range set with reference to the optimal writing power, it is possible to provide a reproduction signal with a stable level even for an optical disc having a substantial material characteristic deviation between its inner and outer peripheral portions.  
           [0018]    However, where an optical disc operating in a low speed mode (for example, at 4X, where ‘X’ denotes a basic reference speed) performs a writing operation in a higher speed mode (for example, at 32X), its writing power is outside of an ROPC margin range from a point substantially corresponding to a point P of FIG. 3 during the ROPC operation, under a condition in which the optical disc has a large material characteristic deviation between its inner and outer peripheral portions (indicated as “C” or “C′” in FIG. 3) in step S 10 . In this case, write failure may occur because there may no longer be any signal discrimination ability in step S 11 . Even when there is no write failure, it is impossible to reproduce written signals.  
         SUMMARY OF THE INVENTION  
         [0019]    The present invention is made in view of the above circumstances and an object of the invention is to provide an apparatus and method for controlling the writing power of an optical disc that substantially obviates the disadvantages of the related art optical disc recording/reproducing apparatus.  
           [0020]    It is an object of the present invention is to provide an apparatus and method for controlling the writing power of an optical disc which is capable of achieving an optimum data writing operation without any write failure even for an optical disc having a large material characteristic deviation between its inner and outer peripheral portions.  
           [0021]    In order to achieve this and other objects, the present invention in one aspect provides a method for recording data on an optical disc, including detecting optimum writing power from a test area on the optical disc; determining whether or not a current writing power is within a predetermined allowable range set with reference to the detected optimum writing power; and performing a writing operation with the writing power controlled to maintain a reflection signal level corresponding to the detected optimum writing power when the current writing power is within the predetermined allowable range, and performing the writing operation with the writing power controlled based on power update information when the current writing power is not within the predetermined allowable range.  
           [0022]    In accordance with another aspect, the present invention provides an apparatus for recording data on an optical disc, including a determining unit for determining, in a writing operation of the writing means, whether or not current writing power is within a predetermined allowable range set with reference to optimum writing power; controller for controlling the writing power to maintain a reflection signal level corresponding to the optimum writing power when the current writing power is within the predetermined allowable range based on the result of the determining unit, and controlling the writing power based on power update information when the current writing power is not within the predetermined allowable range; and writing unit for performing a writing operation with the controlled writing power to write input data to the disc using writing power. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    A more complete appreciation of the 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:  
         [0024]    [0024]FIG. 1 is a block diagram illustrating the configuration of a related art optical disc recording/reproducing apparatus;  
         [0025]    [0025]FIGS. 2 a  and  2   b  are flow charts illustrating a related art data recording method carried out in the general optical disc recording/reproducing apparatus of FIG. 1;  
         [0026]    [0026]FIG. 3 is a diagram depicting a variation in writing power depending on a material characteristic deviation between the inner and outer peripheral portions of an optical disc;  
         [0027]    [0027]FIGS. 4 a  and  4   b  are flow charts illustrating a method for controlling the writing power of an optical disc in accordance with a preferred embodiment of the present invention; and  
         [0028]    [0028]FIG. 5 is a table illustrating an example of power update information stored in accordance with the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0029]    Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, the configuration of an optical disc recording/reproducing apparatus in accordance with the embodiment of the present invention, in which the apparatus for controlling the writing power of an optical disc is embodied, is similar to that of FIG. 1, with notable exceptions. The ROM  71  is further stored with power update information in accordance with the present invention. The microcomputer  70  is configured to control the writing power, based on the power update information selectively given in accordance with the material characteristic deviation between the inner and outer peripheral portions of the optical disc. These features will be described in detail hereinafter.  
         [0030]    [0030]FIGS. 4 a  and  4   b  are flow charts illustrating a preferred embodiment of the method for controlling the writing power of the optical disc in accordance with the present invention. The writing power controlling method of FIGS. 4 a  and  4   b  will now be described in detail in conjunction with the operation of the apparatus shown in FIG. 1.  
         [0031]    In accordance with the present invention, a search is first performed to find optical discs, each having a large material deviation between its inner and outer peripheral portions, in the manufacture of the optical disc recording/reproducing apparatus. For each of the searched optical discs, a detection is carried out to detect the point where the writing power is outside of an ROPC margin range which may be, for example, a point P in FIG. 3, and a variation in writing power per a unit time occurring from the point. The detected point and writing power variation rate are additionally stored as power update information in association with an associated disc code and/or writing speed in the ROM  71  stored with information about optimum write strategies.  
         [0032]    For example, the power update information additionally stored in the ROM  71  may be “Disc A-Writing power Increase of 0.1 mW per Minute from Point P.” 
         [0033]    Accordingly, when the optical disc  10  is loaded into the recording/reproducing apparatus, and subsequently rotated, the microcomputer  70  detects a disc code from ATIP data detected from the optical disc  10 , and identifies an optimum write strategy corresponding to the detected disc code from the internal ROM  71  in step S 21 .  
         [0034]    If a writing operation is subsequently requested in step S 22 , the microcomputer  70  performs the same procedure as the steps of FIGS. 2 a  and  2   b . That is, the microcomputer  70  performs an OPC operation, thereby detecting and storing an optimum writing power and an optimum reflection signal level, or B-level, corresponding to the optimum writing power in step S 23 . The microcomputer  70  subsequently performs a writing operation on the data area of the optical disc  10 , using the detected optimum writing power and the identified optimum write strategy in step S 24 . During the writing operation, the microcomputer  70  determines whether or not an ROPC operation is to be carried out, based on the detected B-level and RF signal level detected by the first and second level detectors  51  and  52 , respectively, in step S 25 .  
         [0035]    If it is determined that it is unnecessary to carry out the ROPC operation in step S 26 , that is, where the optical disc  10  has little material characteristic deviation between its inner and outer peripheral portions, indicated as “A” in FIG. 3, the microcomputer  70  performs a writing operation while maintaining the optimal writing power detected in accordance with the OPC operation until the writing operation is completed in steps S 27  and S 28 . On the other hand, if it is determined that it is necessary to carry out an ROPC operation, that is, where the optical disc  10  has a substantial material characteristic deviation between its inner and outer peripheral portions indicated as “B” or “B′” in FIG. 3, the microcomputer  70  performs the ROPC operation until the writing operation is completed in steps S 29  and S 32 .  
         [0036]    Where the optical disc  10  is adapted for a low speed mode (for example, at 4X) while having a large material characteristic deviation between its inner and outer peripheral portions, its writing power may be outside of an ROPC margin range when a writing operation is carried out for the optical disc in a higher speed mode (for example, at 32X). When the writing power is outside of the ROPC margin range from a point substantially corresponding to the point P in FIG. 3, indicated as “C” or “C′” in FIG. 3 in step S 30 , the microcomputer  70  stops the ROPC operation, and performs a power updating operation in step S 31 . This procedure is carried out as follows.  
         [0037]    First, the microcomputer  70  detects, from the ROM  71  the power update information stored in association with the detected disc code.  
         [0038]    Thereafter, the microcomputer  70  performs the writing operation while varying the writing power at intervals of a certain time until writing of data is completed, based on the detected power update information, and continuously identifying the current time information on the optical disc  10  from ATIP data detected by the ATIP decoder  54 . For example, the microcomputer  70  performs the writing operation while increasing the writing power by 0.1 mW per minute, based on the detected power update information. The writing operation will now be described in brief.  
         [0039]    The digital write signal processor  30   a generates an ECC block by adding an encoding and error correction parity to input coded data to provide a desired reliability for recording/reproduction of the input coded data. The channel bit encoder  40  converts a digital bit stream outputted from the digital write signal processor  30   a  into a pulse-width-modulated (PWM) signal capable of being written on the optical disc  10 . The PWM signal is applied to the optic drive  41 . The microcomputer  70  controls the optic drive  41  to output a write signal, in accordance with an optical drive current corresponding to the variation of the writing power based on the power update information.  
         [0040]    Thus, the optic drive  41  outputs a signal of write data in accordance with optical drive power. corresponding to the PWM signal applied thereto. The optical pickup  20  writes the write signal on the data area of the optical disc  10 .  
         [0041]    Accordingly, it is possible to avoid write failure when a writing operation is carried out in a high speed mode for an optical disc having a large material characteristic deviation. between its inner and outer peripheral portions while being adapted for a low speed mode, while obtaining superior reproduction characteristics.  
         [0042]    [0042]FIG. 5 illustrates an example of power update information stored in association with diverse disc types. Now, another embodiment of the method for controlling the writing power of the optical disc in accordance with the present invention will be described with reference to FIG. 5.  
         [0043]    As shown in FIG. 5, stored in the ROM  71  are respective points P and power update information associated with each point P in association with various writing speeds for each disc type. FIG. 5 illustrates the power update information for an optical disc adapted for a 4X speed mode.  
         [0044]    When the optical disc  10  is loaded into the recording/reproducing apparatus, and subsequently rotated, the microcomputer  70  detects and identifies a point P stored in association with the disc type of the optical disc  10  and a required writing speed, and a power variation rate, from the power update information stored in the ROM  71 . For example, when P is 20:00:00, the required writing speed is 32X and the power variation rate is 0.08 mW/min.  
         [0045]    When the current writing position corresponds to the detected/identified point P during the writing operation in the required writing speed, the microcomputer  70  performs the above described power updating operation from the current writing position until the writing operation is completed. That is, the microcomputer  70  performs the writing. operation while increasing the writing power by 0.08 mW at intervals of 1 minute from the current writing position, based on the detected power variation rate when P is 20:00:00.  
         [0046]    The power variation rate to be stored may be a value obtained by detecting a variation in writing power at intervals of a certain time while starting the detection from the point P.  
         [0047]    As is apparent from the above description, the present invention provides an apparatus and method for controlling the writing power of an optical disc in which, when data is to be written in a high speed mode on an optical disc having a large material characteristic deviation between its inner and outer peripheral portions while being adapted for a low speed mode, the data writing is carried out while varying writing power based on. power update information previously detected and stored, thereby being capable of avoiding write failure while obtaining superior reproduction characteristics.  
         [0048]    Numerous additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.