Patent Publication Number: US-2004057365-A1

Title: Method and apparatus for detecting blank region of optical storage medium

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] This present invention relates to a detection apparatus and a method for detecting blank regions which have not yet recorded data on an optical storage medium.  
       [0003] 2. Description of the Prior Art  
       [0004] While recording data onto an optical storage medium by a driving device of optical storage mediums, it is necessary to be able to discriminate the blank regions which have not yet recorded data thereon from the data recording regions which have recorded data thereon, so as to easily control the relative activities of each component in the driving device and determine regions for recording. The prior art usually utilizes the peak/bottom detection method or slicing level detection method to detect blank regions on an optical storage medium.  
       [0005] Please refer to FIG. 1. FIG. 1 is a schematic diagram of a driving device  01  recording/reproducing data on an optical storage medium  14 . The driving device  01  comprises a light generator  10  and an sensing module  16 . According to the prior art, when the peak/bottom detection method is used to detect blank regions of the optical storage medium  14 , the light generator  10  generates a laser beam  12  irradiating to the optical storage medium  14  and the sensing module  16  is used for receiving the laser beam reflected from the optical storage medium  14  then transforming the reflected laser beam  12  into an electronical signal  18  to be transmitted forward to a detection device  20 . The electronical signal  18 , which is transformed from the reflected laser beam  12 , is generally called radio frequency (RF) signal.  
       [0006] Please refer to FIG. 2 and FIG. 3. FIG. 2 is a block diagram of the detection apparatus  20  shown in FIG. 1. FIG. 3 is a schematic diagram of detecting a RF waveform  08  by the peak/bottom detection method according to the prior art. In the detection apparatus  20 , a peak/bottom detection circuit  02  is used to detect the amplitude of the electronical signal  18 , and the electronical signal  18  is the RF waveform as shown in FIG. 3. The peak/bottom detection circuit  02  uses a sampling clock  04  for sampling the amplitude of the RF. Then during every time unit, a pre-set threshold value  22  is used as a reference base and a comparator  06  is used to compare the sampled amplitude with the reference base to see whether the sampled amplitude is under or below the pre-set threshold value  22 . The RF is deemed to be from the blank regions of the optical storage medium which have not yet recorded data thereon, if the amplitude is below the pre-set threshold value  22 . Otherwise the RF is deemed to be from the data recording regions which have recorded data thereon.  
       [0007] However, it takes time for sampling, and judgment delay may happen because of time lag. When the detection is from a blank region into a data recording region, the signal is actually in the data recording region. Due to the next sampling time is not yet coming, the amplitude information is therefore not yet updated. In such situation, the comparator  06  still uses the former amplitude information to compare with the pre-set threshold value  22 . Hence the detection apparatus  20  will judge that the optical storage medium  14  is still in a blank region, resulting in a misjudgment.  
       [0008]FIG. 4 is a block diagram of an alternative detecting apparatus  48  in the driving device  01  shown in FIG. 1. FIG. 5 is a schematic diagram of detecting the RF waveform  08  by the slicing level detecting method according the prior art. The prior art slicing level detecting method can avoid delays of judgment resulted from time lag of sampling as mentioned above. As shown in FIG. 1 and FIG. 4, the laser beam  12  is transformed to be the electronical signal  18  (not shown in FIG. 1) and then transmitted into the detecting apparatus  48 . In the detecting apparatus  48 , a waveform detection module  36  is used to detect the RF waveform  08  detected from the optical storage medium  14 . Then a predetermined slicing level  30  and a blank judgment interval are selected as a reference base. The upper and lower limits of the blank judgment interval are defined by a positive hysteresis level (PHL)  38  and a negative hysteresis level (NHL)  40 . And the distances from the PHL  38  to the slicing level  30  and from the NHL  40  to the slicing level  30  are the same. Then a blank region judgment module  42  is used to judge that whether the waveform  08  is between NHL  40  and PHL 38 , i.e., within the blank judgment interval. If yes, it means the RF detected by the waveform detection module  36  is from the blank regions. Otherwise, it means the RF detected by the waveform detection module  36  is from the data recording regions.  
       [0009] However, the RF waveform potentially comprises background noises  44  and a plurality of different frequency sinewaves  46 , wherein the higher the frequency sinewave is, the smaller the amplitude is. If the distances of the slicing level  30  to the PHL  38  and the NHL  40  are defined too narrow, the background noises  44  are easily misjudged as the RF from the data recording regions. If the distances of the slicing level  30  to the PHL  38  and to the NHL  40  are defined too spacious, many RF from data recording regions are easily misjudged as the RF from the blank judgment interval, because their amplitudes of sinewave  46  are not enough and fall into the blank judgment interval.  
       [0010] Hence the main objective of the present invention is to provide a method and an apparatus to solve these problems as mentioned above.  
       SUMMARY OF THE INVENTION  
       [0011] The main objective of the present invention is providing a detection apparatus and method for detecting blank regions which have not yet recorded data on an optical storage medium.  
       [0012] The optical storage medium contains data recording regions and blank regions. The data recording regions have recorded a plurality of data thereon, and the blank regions are regions have not yet recorded data thereon. The detecting apparatus comprises a waveform detection module for detecting a RF waveform from the optical storage medium. The RF waveform potentially comprises background noises and a plurality of different frequency sinewaves, wherein the higher the frequency sinewave is, the smaller the amplitude is. The detecting apparatus also comprises a selective gain boost module for selectively boosting the amplitudes of the sinewaves with different boost gains according to the respective frequencies of the input sinewaves in the RF waveform, and obtaining a corresponding gain boost signal.  
       [0013] The detecting apparatus also comprises a blank region judgment module for judging the present gain boost signal with a predetermined blank judgment interval. When the present amplitudes of the gain boost signal fall within the blank judgment interval, the RF waveform detected by the waveform detection module is deemed from the blank regions. Otherwise the RF waveform detected by the waveform detection module is deemed from the data recording regions.  
       [0014] The detecting apparatus of the present invention can precisely detect the blank region which have not yet recorded data on an optical storage medium and further reduce potential misjudgment.  
       [0015] These and other objective of the present invention will no doubt become obvious to those of ordinary skill in the art after reproducing the following detailed description of the preferred embodiment which is illustrated in the various figures and drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE APPENDED DRAWINGS  
     [0016]FIG. 1 is the schematic diagram of a prior art driving device of optical storage medium, which is recording and reproducing data from an optical storage medium.  
     [0017]FIG. 2 is the block diagram of the detecting apparatus as FIG. 1 shows.  
     [0018]FIG. 3 is the schematic diagram of prior art peak/bottom detection method to detect the RF waveforms.  
     [0019]FIG. 4 is the block diagram of a detecting apparatus for another implementation example of the driving device of optical storage medium.  
     [0020]FIG. 5 is the schematic diagram of the prior art slicing level detecting method to detect the RF waveforms.  
     [0021]FIG. 6 is the block diagram of the detecting apparatus of the present invention.  
     [0022]FIG. 7 is a signal relationship diagram for the detecting apparatus to detect blank regions according to a predetermined slicing level.  
     [0023]FIG. 8 is the flowchart for the detecting method of the detecting apparatus as FIG. 6 shows. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0024] Please refer to FIG. 6 and FIG. 7. FIG. 6 is a block diagram of a detecting apparatus  51  of the present invention. FIG. 7 is a schematic diagram of the signals when the detecting apparatus  51  using a predetermined slicing level  50  to detect blank regions. The present invention provides a detecting apparatus  51  for detecting blank regions on an optical storage medium. The optical storage medium (not shown in figures) contains data recording regions and blank regions. The data recording regions are regions on the optical storage medium which have recorded a plurality of data thereon. The blank regions are regions on the optical storage medium which have not yet recorded data thereon.  
     [0025] The detecting apparatus  51  comprises a waveform detection module  52 , a programmable gain amplifier  56 , a selective gain boost module  54  and a blank region judgment module  58 .  
     [0026] The waveform detection module  52  is for detecting a RF waveforms  61  from the optical storage medium. The RF waveform  61  potentially comprises background noises  62  and a plurality of different frequency sinewaves  64 . Meanwhile a fact exists that the higher the frequency is, the smaller the amplitude is for any sinewave  64  of RF waveform  61  detected from the optical storage medium. The programmable gain amplifier  56  is for amplifying the RF waveform  61  detected by the waveform detection module  52 , and then outputting the amplified waveform to the selective gain boost module  54 .  
     [0027] The selective gain boost module  54  is for selectively boosting the amplitudes of the sinewave  64  with different boost gains according to the respective frequencies of the input sinewaves  64  in the RF waveform  61 , and then obtaining a corresponding gain boost signal  66 . The higher frequency the sinewave  64  is, the bigger gain the amplitude needs. Generally speaking, the gain from the selective gain boost module  54  is substantially from 3 dB to 13 dB.  
     [0028] The blank region judgment module  58  is for judging the present gain boost signal  66  according to a predetermined blank judgment interval. The PHL  68  and NHL  70  define the upper and lower limits of the blank judgment interval, respectively. When the present amplitudes of the gain boost signal  66  fall within the blank judgment interval, the RF waveform  61  detected by the waveform detection module  52  is deemed from the blank regions, otherwise the RF waveform  61  detected by the waveform detection module  52  is deemed from the data recording regions. The selective gain boost module  54  will boost the amplitude of the input sinewave  64  of the RF waveform  61  which has higher frequency over the PHL  68  and the NHL  70 . When the RF waveform  61  is detected from the data recording region, the RF waveform  61  comprises background noises  62  and a plurality of different frequency sinewaves  64 . When the RF waveform  61  is detected from the blank regions, the RF waveform  61  comprises only background noises  62  but no sinewaves  64 .  
     [0029] The blank region judgment module  58  will generate a corresponding judgment signal  72 , so-called blank flag that is commonly known in the art. The judgment signal  72  comprises a first judgment level  74  and a second judgment level  76 . When the amplitude of the present gain boost signal  66  is beyond the blank judgment interval, the judgment signal  72  is situated in the first judgment level  74 , wherein the first judgment level  74  represents the data recording regions on an optical storage medium. When the amplitude of the present gain boost signal  66  is within the blank judgment interval, the judgment signal  72  is situated in the second judgment level  76 , wherein the second judgment level  76  represents the blank regions on an optical storage medium.  
     [0030] As the FIG. 6 shows, the blank region judgment module  58  comprises a slicing comparator  59  and a H/L pulses detector  60 . The slicing comparator  59  is for setting the blank judgment interval on a predetermined slicing level, slicing the present gain boost signal  66 . The H/L pulses detector  60  will determine whether the judgment signal  72  should be situated in the first judgment level  74  or the second judgment level  76  by the result of the slicing comparator, and determining whether the RF waveform  61  detected by the waveform detection module  52  is from the data recording regions or the blank regions.  
     [0031] Please refer to FIG. 8. FIG. 8 is a flow chart for the detecting method of the detecting apparatus  51  shown in FIG. 6. The detecting method of the present invention comprises the following steps:  
     [0032] Step S 82 : detecting the RF waveform  61  from the optical storage medium;  
     [0033] Step S 84 : amplifying the RF waveform  61  detected;  
     [0034] Step S 86 : selectively boosting the amplitudes of the sinewaves  64  with different boost gains according to the respective frequencies of the sinewaves  64  in the RF waveform  61  to obtain a corresponding gain boost signal  66 ;  
     [0035] Step S 88 : judging the present gain boost signal  66  whether it is within a predetermined blank judgment interval;  
     [0036] Step S 92 : slicing the present gain boost signal  66  according to the blank judgment interval on a predetermined slicing level to determine whether the judgment signal  72  should be situated in the first judgment level  74  or the second judgment level  76 ;  
     [0037] Step S 94 : determining the RF is from the data recording regions or the blank regions according to whether that the judging signal  72  is situated in the first judging level  74  or the second judging level  76 .  
     [0038] When the amplitude of the present gain boost signal  66  within the blank judgment interval, it means that the RF waveform  61  detected by the waveform module  52  is from the blank regions, otherwise the RF waveform  61  detected by the waveform module  52  is from the data recording regions. Therein the input amplitude of the sinewaves  64  of the input RF waveform  61  which has higher frequencies is boosted over the extent of the blank judgment interval, namely over the PHL  68  and NHL  70 . When the RF signal is reproduced from the data recording regions, the RF signal comprises background noises  62  and different frequency sinewaves  64 . When the RF signal is reproduced from the blank regions, the RF signal comprises only background noises  62  but no sinewaves  64 .  
     [0039] Please refer to FIG. 7. A corresponding judgment signal  72  is generated. The judgment signal  72  comprises a first judgment level  74  and a second judgment level  76 . When the amplitude of the present gain boost signal  66  is over the blank judgment interval, the judgment signal  72  will be situated in the first judgment level  74 . When the amplitude of the gain boost is within the blank judgment interval, the judgment signal  72  will be situated in the second judgment level  76 .  
     [0040] Hence the present invention provides a detecting apparatus  51  and a detecting method for detecting blank regions which have not yet recorded data on an optical storage medium. The detecting method is to detect a RF waveform  61  from the optical storage medium, wherein the RF waveform  61  comprises a plurality of different frequency sinewaves  64 , and then to selectively boost the amplitude of sinewaves  64  by different boost gain according to the different frequency of sinewave  64  of the RF waveform  61  to obtain a corresponding gain boost signal  66 , and further to judge the present gain boost signal with a predetermined blank judgment interval. When the amplitude of the present gain boost signal is within the blank judgment interval, it means the RF signal detected by the waveform detection module  52  is from the blank regions. Whereby, the method of the present invention can more precisely detect the blank regions which have not yet recorded data thereon of the optical storage medium.  
     [0041] With the examples and explanations above, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.