Abstract:
A method is used for calibrating a writing power of an optical storage carrier player. The player has an access device for writing data onto the optical storage carrier. The carrier includes a center, an inner power calibration area (first calibration area), a data storage area, and an outer power calibration area (second calibration area). The method determines a writing location of the data in the data storage area, and controls the access device to perform an optical power calibration process in either the inner power calibration area or the outer power calibration area according to the writing location. Once completed, the method then utilizes a result of the optical power calibration process to determine a required writing power, and finally controls the access device to write the data to the optical storage carrier in the writing location with the required writing power.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority to Taiwan Patent Application Serial No. 090103480 entitled “Optical Power Calibration Method According to a Data Writing Location,” filed 15 Feb. 2001. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an optical power calibration method, and more particularly, to an optical power calibration method for calibrating a writing power of an optical storage carrier player, such as a Compact Disc Read/Write drive, according to a data writing location optical storage carrier. 
   2. Description of the Prior Art 
   A Compact Disc Read/Write drive can write data to recordable compact discs that can subsequently be read in any Read-Only-Memory Compact Disc (CD-ROM) drive and in the CD-R/W drive. Generally, the CD-R/W drive performs an optical power calibration process before writing data onto a compact disc. The optical power calibration process pre-writes specific information onto a Power Calibration Area (PCA) located at an inside area of the compact disc. Next, the written information is read to determine a required writing power to write the data to the compact disc correctly. 
   Please refer to  FIG. 1  of a schematic view of a compact disc  10  according to the prior art. The prior art compact disc  10 , which is standardized according to an Orange Book, comprises a center  12 , a Power Calibration Area  14  located outside of the center  12  for optical power calibration, and a data storage area  16  located outside of the Power Calibration Area  14 . Data is written into the data storage area  16 . Before writing data onto the compact disc  10 , the prior art CD-R/W drive performs an optical power calibration process in the Power Calibration Area  14  to determine power parameters. That is, the prior art CD-R/W drive uses properties such as surrounding and vibrational characteristics of the Power Calibration Area  14  to simulate conditions within the whole data storage area  16  so as to determine the appropriate writing power. 
   Nevertheless, the Power Calibration Area  14  is located at an inside area of the compact disc  10 , but a considerable portion of the data storage area  16  is located at an outside area of the compact disc  10 . Since the surrounding and vibrational characteristics of the compact disc  10  have differences between the inside and the outside area, the prior art optical power calibration method is incapable of acquiring an optimum writing power, thus resulting in a bad writing quality. 
   SUMMARY OF THE INVENTION 
   It is therefore one aspect of the present invention to provide an optical power calibration method to solve the above-mentioned problem. 
   According to one aspect of the invention, the invention provides an optical power calibration method for calibrating a writing power of an optical storage carrier player, such as a Read/Write Compact Disc (CD/R/W) drive. The CD-R/W drive has an access device for writing data onto a compact disc. The optical storage carrier, such as the compact disc, comprises a center, an inner power calibration area (first power calibration area) located outside of the center for optical power calibration, a data storage area located outside of the inner power calibration area, and an outer power calibration area (second power calibration area) located outside of the data storage area for optical power calibration. 
   The optical power calibration method includes following steps: (a) providing data to be written, and (b) determining a writing location for the data in the data storage area. Finally, (c) controlling the access device to perform an optical power calibration process in either the inner power calibration area or the outer power calibration area according to the writing location. The access device performs the optical power calibration process in (a) the first power calibration area when the writing location is within the predetermined portion, or (b) the second power calibration area when the writing location is out of the predetermined portion. The calibration method then utilizes the result of the optical power calibration process to determine the required writing power, and controlling the access device to write the data to the compact disc in the writing location with the required writing power. 
   It is an advantage of the claimed invention that the optical power calibration method according to the claimed invention performs an optical power calibration process in either the inner power calibration area or the outer power calibration area according to the writing location of the data. 
   These and other objectives and advantages of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of a compact disc according to the prior art. 
       FIG. 2  is a schematic diagram of a Compact Disc Read/Write drive according to the present invention. 
       FIG. 3  is a schematic diagram for controlling of the CD-R/W drive shown in  FIG. 2 . 
       FIG. 4  is a flow chart of an optical power calibration method according to the preferred embodiment of the present invention. 
       FIG. 5  is a schematic diagram of an alternative preferred embodiment of the present invention. 
       FIG. 6  is a flow chart of an optical power calibration method according to the preferred embodiment shown in  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Please refer to  FIG. 2  of a schematic diagram of a Compact Disc Read/Write drive  30  according to the present invention. The CD-R/W drive  30  comprises an access device  32  for writing data onto a compact disc  34 , and a control device  36  for controlling operations of the CD-R/W drive  30 . The control device  36  controls the access device  32  to perform an optical power calibration process, and utilizes a result of the optical power calibration process to write the data to the compact disc  34 . 
   As shown in  FIG. 2 , from the inside to the outside, the compact disc  34  sequentially comprises a center  38 , an inner power calibration area  40  for optical power calibration, a data storage area  46  where data is written, and a last possible lead-out area  48  for storing ending information about the data on the compact disc  34 . According to a compact disc standard, the most outside area of each compact disc must remain an appropriate region for storing ending information about data, i.e., the last possible lead-out area  48 . However, the optical power calibration process can be performed in the inner power calibration area  40  for one hundred times. In this invention, the extra outer power calibration area  52  is defined in the last possible lead-out area  48 . 
   According to the compact disc standard mentioned in the Orange Book, the length of the last possible lead-out area  48  must be at least longer than 01:30:00, some manufacturers even manufacturer a compact disc with a last possible lead-out area of 01:50:00. Generally, fifteen frames are required to perform an optical power calibration process once. Thus 1,500 frames are required to perform the optical power calibration process one hundred times, which takes twenty seconds (00:20:00). Hence, enough length of the last possible lead-out area  48  is reserved for storing the ending information, and then the outer power calibration area  52  can utilize the rest of the lead-out area  48  for optical power calibration. In the preferred embodiment according to the present invention, the outer power calibration area  52  is located from 01:00:00 to 01:20:60 after a last possible start time  50 . 
   Please refer to  FIG. 3  of a schematic diagram for controlling of the CD-R/W drive  30  shown in  FIG. 2 . In a preferred embodiment of the present invention, the CD-R/W drive  30  controls rotation of the compact disc  34  in a constant linear velocity (CLV) manner, so that data units on different tracks of the compact disc  34  have the same linear velocity while passing through the access device  32 . From the point of view of an angular velocity of the compact disc  34 , when writing onto data units near the center  38  of the compact disc  34 , the compact disc  34  has a higher angular velocity. Oppositely, when writing onto data units near the outside area of the compact disc  34 , the compact disc  34  has a lower angular velocity. 
   The CD-R/W drive  30  performs an optical power calibration process in either the inner power calibration area  40  or the outer power calibration area  52  according to a writing location of data. As shown in  FIG. 3 , the preferred embodiment of the present invention divides the data storage area  46  into an inner area  46   a  and an outer area  46   b . When writing data, the control device  36  determines a writing location for the data into the data storage area  46 . When the writing location is located within the inner area  46   a , the CD-R/W drive  30  performs the optical power calibration process in the inner power calibration area  40  shown in  FIG. 2 . When the writing location is out of the inner area  46   a , and located in the outer area  46   b , the CD-R/W drive  30  performs the optical power calibration process in the outer power calibration area  52 . 
   Please refer to  FIG. 4  of a flow chart of an optical power calibration method according to the preferred embodiment of the present invention. The optical power calibration method of the present invention comprises: 
   step 100: dividing the data storage area  46  into an inner area  46   a  and an outer area  46   b;  
         step 102: providing data to be written;   step 104: determining a writing location of the data in the data storage area  46 ;   step 106: controlling the access device  32  to perform an optical power calibration process in either the inner power calibration area  40  or the outer power calibration area  52  according to the writing location. When the writing location is located in the inner area  46   a , the access device  32  performs the optical power calibration process in the inner power calibration area  40 . When the writing location is located in the outer area  46   b , the access device  32  performs the optical power calibration process in the outer power calibration area  52 ;   step 108: controlling the access device  32  to write the data to the compact disc  34  in the writing location with the required writing power.       

   Since the inner area  46   a  is adjacent to the inner power calibration area  40 , and the outer area  46   b  is adjacent to the outer power calibration area  52 , the surrounding and vibrational characteristics of the inner area  46   a  and the outer area  46   b  are close to that of the inner power calibration area  40  and the outer power calibration area  52  respectively. Therefore, the optical power calibration method according to the present invention can precisely predict an optimum writing power in the data storage area  46  to enhance the writing quality. 
   In addition to the CLV manner described previously, the CD-R/W drive  30 , which controls rotation of the compact disc  34  in a constant angular velocity (CAV) manner, is also applicable to the optical power calibration method of the present invention as well. 
   Please refer to  FIG. 5  of a schematic diagram of an alternative preferred embodiment of the present invention. Different from the previously mentioned embodiment, the CD-R/W drive  30  does not control rotation of the compact disc  34  in a CLV manner or a CAV manner, but in a multi-stage linear velocity manner instead. As shown in  FIG. 5 , the data storage area  46  of the compact disc  34  is divided, from the inside to the outside, into five data segments Z 1 , Z 2 , Z 3 , Z 4  and Z 5 . The CD-R/W  30  controls rotation of the compact disc  34  in each segment Z 1 , Z 2 , Z 3 , Z 4 , Z 5  in a constant linear velocity (CLV) manner, each segment Z 1 , Z 2 , Z 3 , Z 4 , Z 5  has a different linear velocity V 1 , V 2 , V 3 , V 4 , V 5  respectively, but each segment Z 1 , Z 2 , Z 3 , Z 4 , Z 5  has the same initial angular velocity W 0 . 
   In this preferred embodiment of the present invention, the control device  36  determines a writing location for data to be written into the data segment Z 1 , Z 2 , Z 3 , Z 4 , or Z 5  of the data storage area  46 . It then controls the access device  32  to perform an optical power calibration process in either the inner power calibration area  40  or the outer power calibration area  52  according to the writing location. When the writing location is within the inner three data segment Z 1 , Z 2 , or Z 3  (the predetermined portion of the data storage area  46 ), the CD-R/W drive  30  controls the access device  32  to perform the optical power calibration process in the inner power calibration area  40 . When the writing location is within the outer two data segment Z 4  or Z 5 , the control device  36  controls the access device  32  to perform the optical power calibration process in the outer power calibration area  52 . 
   Please refer to  FIG. 6  of a flow chart of an optical power calibration method according to the preferred embodiment shown in  FIG. 5 . The optical power calibration method according to the preferred embodiment shown in  FIG. 5  comprises:
         step 200: providing N data segments Z 1  to Z N  for controlling rotation of the compact disc  34  in a multi-stage linear velocity manner;   step 202: providing data to be written;   step 204: determining a writing location of the data in the data storage area  46 ;   step 206: controlling the access device  32  to perform an optical power calibration process in either the inner power calibration area  40  or the outer power calibration area  52  according to the writing location. When the writing location is located in the inner M (M&lt;N) data segments (Z 1 ˜Z M ), the access device  32  performs the optical power calibration process in the inner power calibration area  40 . When the writing location is located in the outer N-M data segments (Z M+1 ˜Z N ), the access device  32  performs the optical power calibration process in the outer power calibration area  52 ;   step 208: controlling the access device  32  to write the data to the compact disc  34  in the writing location with the required writing power.       

   The M value can be a half of the N value. Naturally, to choose an optimum optical power calibration area according to the writing location, the M and N values can be defined depending on the relative factors. 
   In contrast to the prior art, the optical power calibration method according to the present invention performs the optical power calibration process in either the inner power calibration area or the outer power calibration area according to the writing location of data. Therefore an exact writing power for the data storage area  46  can be predicted precisely so as to enhance the writing quality. 
   Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.