Patent Publication Number: US-2004052183-A1

Title: Data recording and reproducing apparatus, method, and medium including computer readable code therefor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001] This application claims the priority of Korean Patent Application No. 2002-56816 filed on Sep. 18, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
       BACKGROUND OF THE INVENTION  
       [0002] 1. Field of the Invention  
       [0003] The present invention relates to apparatuses for recording and reproducing data in disc-type recording media, methods therefor, and medium including computer readable code controlling a computer to perform the same. More specifically, the present invention is directed toward data recording and reproducing data in a disc-type recording medium by varying an optical recording power level based on a recording speed of the disc-type recording medium.  
       [0004] 2. Description of the Related Art  
       [0005]FIGS. 1A and 1B are graphs illustrating power levels of light, over time, emitted by an optical pickup to record data on a recording medium. More specifically, FIG. 1A illustrates power levels of light emitted by an optical pickup to record data in a CD-R disc-type recording medium. A pit is formed in the recording medium during a light-emitting period between A and B on the time-axis. On the other hand, during the periods when only a read power level is emitted, a pit is not formed. During these periods where only a read power level is emitted, a wobble signal, which can be formed along a track of the recording medium and represents address information, as well as a servo signal, can both be detected by light reflected off the recording medium.  
       [0006] To maintain uniform optical power levels, such as the read power level, during a recording operation, a power level of the light emitted from the pick-up is detected using an optical detection unit, such as a photo diode, and is fed back to an automatic power control (APC) circuit. The APC circuit compares the feedback signal with a reference signal and controls the output read power level to be uniform. However, the read power level can be reduced or fluctuate due to noise, which can increase with higher recording speeds. The power levels can also be reduced or caused to fluctuate due to non-ideal characteristics of parts. Thus, the actual read power level for recording to the recording medium is lower than the preset read power level. As a result, recording quality may be lowered.  
       [0007]FIG. 1B illustrates power levels of light emitted by an optical pickup for recording data in a CD-RW disc-type recording medium. Existing data in the recording medium is erased during the period where the power level of the emitted light is equivalent to the erase power level plus a bias power level. A pit is formed during the period where the power level of the emitted light is equivalent to the peak power level plus the erase power level plus the bias power level. As specifically illustrated in FIG. 1B, data is recorded on the recording medium during a period between X and Y on the time-axis. In the CD-RW disc, the bias power level performs a similar function as the read power level in a CD-R disc. Like the CD-R disc, the CD-RW disc may also suffer from degradation of recording quality because of the bias power level being reduced with increases in recording speeds.  
       SUMMARY OF THE INVENTION  
       [0008] Accordingly, it is an aspect of the present invention to provide a data recording or recording and reproducing apparatus, method therefor, and medium including computer readable code to control a computer to perform the same, to minimize degradation of recording quality even when recording speeds increase.  
       [0009] Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.  
       [0010] To achieve the above and/or other aspects of the present invention, there is provided a data recording method, including obtaining discrimination information for discriminating a recording medium type of a recording medium inserted into a recording or recording and reproducing apparatus, determining a read power level for reading information from the recording medium based on both the discrimination information and a recording speed for recording data on the recording medium, and recording data on the recording medium using the read power level and at least one recording power level.  
       [0011] To achieve the above and/or other aspects of the present invention, there is provided a data recording or recording and reproducing apparatus including a memory to store discrimination information, for discriminating a recording medium type of a recording medium, and read power level information including recording speeds corresponding to the discrimination information, a pickup driving unit to receive information read off the recording medium from a pickup or to output a signal to control the pickup, and a system control unit to receive the discrimination information of the recording medium from the pickup driving unit, determining a read power level for reading information from the recording medium, based on the read power level information, corresponding to the discrimination information, and outputting a signal reflecting the determined read power to the pickup driving unit.  
       [0012] To achieve the above and/or other aspects of the present invention, there is provided a data recording method including controlling a varying of a read power level of an optical pickup, for reading information from a recording medium, and a recording speed, for recording information to the recording medium, to change predetermined amounts, respectively, based on an area of the recording medium information is to be recorded to, and recording the information to the recording medium using the controlled read power level and recording speed. The read power level and recording speed changes may be based on a determined type of the recording medium.  
       [0013] To achieve the above and/or other aspects of the present invention, there is provided a data recording or recording and reproducing apparatus including a pickup to record information to a recording medium at a variable recording speed, and a controller to control a read power level of an optical pickup, for reading information from the recording medium, to change a predetermined amount as the recording speed changes a predetermined amount. Again, the read power level and recording speed changes may be based on a determined type of the recording medium.  
       [0014] Still further, to achieve the above and/or other aspects of the present invention, there is provided a data recording method controlling a varying of a read power level of an optical pickup, for reading information from a recording medium, and a recording speed, for recording information to the recording medium, to change predetermined amounts, respectively, based on a wobble and/or servo signal read from the recording medium, and recording information to the recording medium at the controlled read power level and recording speed.  
       [0015] In addition, to achieve the above and/or other aspects of the present invention, there is provided data recording or recording and reproducing apparatus a pickup to record information to a recording medium at a variable recording speed, and a controller to control a read power level of an optical pickup, for reading information from the recording medium, to change a predetermined amount based on a change in recording speed of a predetermined amount, which is based on a wobble or servo signal read from the recording medium.  
       [0016] Lastly, to achieve the above and/or other aspects of the present invention, there is also provided a medium including computer readable code controlling a computer to control the execution of aforementioned methods, or a medium including computer readable code controlling a computer to control the operation of the aforementioned data recording or recording and reproducing apparatuses.  
       [0017] These, together with other aspects and/or advantages that will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part thereof. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0018] These and other objects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiments taken in conjunction with the accompanying drawings in which:  
     [0019]FIGS. 1A and 1B are graphs illustrating output power levels of light emitted to read and record data to and from a recording medium;  
     [0020]FIG. 2 is a block diagram illustrating a data recording and reproducing apparatus according to an embodiment of the present invention; and  
     [0021]FIG. 3 is a flowchart illustrating a data recording method according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0022] Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.  
     [0023] Throughout the present application, read power levels refer to optical power levels of light emitted from a pickup to at least read out a wobble signal or servo signal reflecting an address during data recording.  
     [0024]FIG. 2 is a block diagram illustrating a data recording and reproducing apparatus according to an embodiment of the present invention. The data recording apparatus includes a recording medium  100 , a pickup  110 , a pickup driving unit  120 , a system control unit  130 , a memory  140 , a spindle motor  150 , and a motor driving unit  160 .  
     [0025] The recording medium  100  is a recording medium capable of optical recording, such as CD-R and CD-RW discs. A wobble signal reflecting an address of a region where data will be recorded can be formed along a track. The address may be changed to an absolute time information reflecting a recording time of data.  
     [0026] The pickup  110  emits light having a read power level to the recording medium  100  prior to data recording, reads the wobble signal from the recording medium  100 , and determines an address therefrom where data will be recorded on the recording medium  100 . After determining the address for data recording, the pickup  110  emits light to the recording medium  100  so as to form a pit or not to form a pit, thereby producing a region corresponding to data values of “1” or “0”, respectively.  
     [0027] The pickup driving unit  120  controls an operation of the pickup  110  in response to the control of the system control unit  130 .  
     [0028] The memory  140  stores optical power level information corresponding to each recording speed for each type of recording medium, e.g., each disc-type recording medium. A recording medium type of the recording medium  100  can be discriminated based on whether the recording medium  100  is CD-R, CD-RW, or DVD, for example. If the recording medium  100  is a CD-R disc, the recording medium  100  would then be discriminated again based on corresponding manufacturer information. Examples of optical power level information corresponding to each recording speed, stored in the memory  140 , is shown in the following table.  
                           TABLE 1                       Recording   Read power   Base power   Recording address       speed   (mW)   (mW)   (number)                                                16×   1.6   20       0˜36,992       20×   1.7   30    36,993˜86,927       24×   1.8   40    86,928˜145,931       28×   2.0   50   145,932˜215,917       32×   2.5   60   215,918˜End                  
 
     [0029] In conventional methods, read power levels are fixed to a uniform value, for example, 1.5 mW, regardless of a recording speed. However, in the present invention, as shown in Table 1, the read power level can be augmented based on an increase in recording speed. The base power and overdrive power can be determined by conventional methods.  
     [0030] When power is supplied to the recording and reproducing apparatus illustrated in FIG. 2, which may also merely be a recording apparatus without a reproducing capability, the system control unit  130  reads out optical power level information for each recording medium type and for each recording speed. Next, when recording medium  100  is inserted into the recording and/or reproducing apparatus, the system control unit  130  reads out discrimination information recorded in the recording medium  100 , e.g., information on whether the recording medium  100  is a CD-R disc or a CD-RW disc and information regarding the manufacturer of the disc, and then determines a recording medium type. The system control unit  130  receives data to be recorded in response to a data recording command from a user, and controls the pickup driving unit  120 , so as to emit light having a particular optical power level for each recording speed, corresponding to the determined discrimination information of the disc. As a result, recording data is recorded in the recording medium  100 .  
     [0031] Hereinafter, operations of the system control unit  130  will be described in detail with reference to Table 1. In the case where the system control unit  130  receives a data input command from a user and thus records data starting from address number 0 of a disc-type recording medium, for example, data is recorded from address number 0, which may be the most inner portion of a data region of the disc, to address number 36,992, at a recording speed of 16× and with a read power level of 1.6 mV, a base power level of 20 mV, and an overdrive power level of 15% to 25% of the base power level.  
     [0032] Data is recorded by forming or not forming a pit on the disc. While light corresponding to the read power level is emitted to the disc, a pit is not formed, thereby resulting in the production of a region representing a data value of “0.” Then, a light-receiving element (not shown), such as a photo diode in the pickup  110 , receives a reflected light from the disc and outputs a current signal proportional to the power level of the reflected light. The current signal is then processed to determine the next address where data will be recorded and to produce a servo signal. For example, the system control unit  130  reads out the wobble and servo signals with a read power of 1.6 mW at a speed of 16×, and records data from number 0 to number 36,992. When the system control unit  130  determines from the read wobble signal that the next address number is 36,993, the motor driving unit  169  is then controlled to increase the recording speed up to a speed of 20× and the pickup driving unit  120  is controlled to increase the read power level from 1.6 mW to 1.7 mW. As described above, as a recording speed for recording data in a recording medium increases, the read power level can be augmented so as to increase the power level of light reflected from the recording medium. A benefit of this augmentation is that the signal to noise ratio (SNR) is improved. Accordingly, as light of a corresponding read power level is emitted to the recording medium, the quality of servo and wobble signal determination is greatly improved. An improvement in the servo signal increases the accuracy of the servo, thereby optimizing recording quality.  
     [0033] The spindle motor  150  directly spins the recording medium  100  such that the recording medium  100  is spun at a desired speed, in response to the control of the motor driving unit  160 .  
     [0034] The motor driving unit  160  controls the spin of the spindle motor  150 , in response to the control of the system control unit  130 .  
     [0035]FIG. 3 is a flowchart illustrating a data recording method according to an embodiment of the present invention.  
     [0036] When a disc is inserted in the recording and reproducing apparatus of FIG. 2, for example, the system control unit  130  reads out discrimination information recorded in the disc, e.g., information on whether the disc is CD-R or CD-RW and the manufacturer of the disc, and thus determines a disc type (operation  210 ).  
     [0037] The system control unit  130  refers to the discrimination information of the disc and thus reads out each optical power level information for each recording speed, corresponding to the discrimination information, from the memory  140  (operation  220 ).  
     [0038] The system control unit  130  receives the present address, where data obtained from reflected light of the light emitted at the read power will be recorded (operation  230 ).  
     [0039] The system control unit  130  determines whether the present address corresponds to a data recording region (operation  240 ). If the present data does not correspond to a data recording region, the data recording is completed.  
     [0040] If the present address corresponds to a data recording region, the system control unit  130  determines whether a recording speed is to be changed at the present address (operation  250 ). As shown in Table 1, address numbers 36,993, 86,928, 145,932, and 215,918 correspond to addresses where the recording speed is changed.  
     [0041] If the recording speed is to be changed, at the present address, the system control unit  130  controls the motor driving unit  169  to change the recording speed and controls the pickup driving unit  120  to change the read power level with the change in the recording speed (operation  260 ).  
     [0042] The system control unit  130  controls data to be recorded in the disc  100  based on the determined recording speed and read power level (operation  270 ). In the case of a recording apparatus for recording data in a CD-R disc, the system control unit  130  can be set to an initialization value such that data is initially recorded at a recording speed of 16×, with a read power level of 1.6 mW.  
     [0043] Embodiments of the present invention may be embodied in a general purpose digital computer, or computers, by running a program from a computer readable medium, including but not limited to storage media such as magnetic storage media (e.g., ROMs, floppy discs hard discs, etc.), optically readable media (e.g., CD-ROMs, DVDs, etc.) and carrier waves (e.g., transmissions over the Internet). The computer readable recording medium can also be dispersively installed in a computer system connected to a network, and stored and executed as a computer readable code by a distributed computing environment.  
     [0044] As set forth above, a data recording or recording and reproducing apparatus, method, and computer readable medium, according to embodiments of the present invention, can control the augmentation of read power levels in proportion to increases in a recording speed for recording data in a recording medium. Thus, reproduction quality of servo and wobble signals are improved. Further, as the servo signal is improved in quality, the accuracy of the servo of the recording apparatus is increased, which leads to improvements in recording quality.  
     [0045] Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.