Abstract:
The present invention relates to a method of recording data onto an optical disk using a write strategy that corresponds to the recording features of the optical disk. The present method detects a track pitch or storage capacity of a recording medium, adjusts a write strategy according to the detected track pitch or storage capacity wherein the write strategy has been chosen to correspond to the manufacturer of the recording medium, and records input data onto the recording medium using the adjusted write strategy. Accordingly, data quality during later reproduction is improved even though it is recorded onto a non-standard disk that is larger in capacity than the standard.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a method of recording data onto an optical disk using a write strategy that corresponds to the recording features of the optical disk.  
           [0003]    2. Description of the Related Art  
           [0004]    In general, characteristics of writable disks are different, the differences being dependent upon their respective manufacturing companies.  
           [0005]    Therefore, a disk device such as a CD writer conducts an optimal power calibration (OPC) using a certain standard writing power for a given disk manufacturer in order to obtain optimal writing power before data is recorded onto a writable disk.  
           [0006]    In addition, write strategies for writable disks are also different among disk manufacturing companies. Thus, a microcomputer of a disk device stores information for a particular write strategy of each company for a disk of standard storage capacity, e.g., 74 minutes, and it detects which company is the manufacturer of an inserted disk. Then, it reads the write strategy that is suitable for that company and writes data onto the inserted disk while adjusting pulse level and/or width of writing pulses of an optimal power according to the read/write strategy.  
           [0007]    On the other hand, the track pitch of a writable disk may vary according to disk storage capacity. For example, if a disk has standard storage capacity (74 min.) its track pitch is about 1.6 μm, however, if a disk has an 80-minute storage capacity its track pitch is narrower than 1.6 μm.  
           [0008]    However, regardless of such a difference, a conventional disk device uses write strategy for standard storage capacity even though an inserted disk has 80-minute capacity or longer. In such a case an optimal writing of data onto an inserted disk cannot be ensured.  
           [0009]    In addition, a disk manufacturing process includes material sputtering which makes an outer part of a disk thicker than an inner part. Because of the thickness difference, recording characteristic is deteriorated as the recording point moves toward the outer regions of a disk.  
           [0010]    For preventing such deterioration, writing power is increased gradually. However, the more writing power is increased the worse interference between neighboring tracks becomes. Because a disk having storage capacity greater than the standard 74 minutes is narrower in track pitch, interference between tracks becomes more severe than a standard capacity disk when writing power is increased at an outer region.  
         SUMMARY OF THE INVENTION  
         [0011]    It is an object of the present invention to provide a data recording method which determines an optimal writing strategy suitable to a disk condition such as track pitch or storage capacity, and records signals onto a writable disk in accordance with the determined writing strategy.  
           [0012]    A method of recording data onto a recording medium in accordance with the present invention is characterized in that it comprises the steps of: detecting a track pitch or storage capacity of a recording medium; adjusting a write strategy according to the detected track pitch or storage capacity wherein the write strategy has been chosen suitably for a manufacturer of the recording medium; and recording input data onto the recording medium using the adjusted write strategy.  
           [0013]    Another method of recording data onto a recording medium in accordance with the present invention is characterized in that it comprises the steps of: detecting storage capacity of a recording medium; detecting a current recording position on the recording medium in case that the detected storage capacity is larger than a preset value; and adjusting a write strategy chosen suitably for a manufacturer of the recording medium, if the detected current position is beyond a predetermined location. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The accompanying drawings, which are included to provide a further understanding of the present invention, illustrate the preferred embodiments of the invention, and together with the description, serve to explain the principles of the present invention, and wherein:  
         [0015]    [0015]FIG. 1 is a simplified block diagram of a disk drive in which a data recording method of the present invention is embedded;  
         [0016]    [0016]FIG. 2 is a flow chart of the first embodiment of a data recording method in accordance with the present invention;  
         [0017]    [0017]FIG. 3 shows an example in which pulse duration is adjusted to be longer according to the present invention;  
         [0018]    [0018]FIG. 4 is a flow chart of the second embodiment of a data recording method in accordance with the present invention; and  
         [0019]    [0019]FIG. 5 shows illustrative information on write strategies stored for different storage capacities. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0020]    In order that the-invention may be fully understood, preferred embodiments thereof will now be described with reference to the accompanying drawings.  
         [0021]    [0021]FIG. 1 is a simplified block diagram of a disk drive in which a data recording method of the present invention is embedded.  
         [0022]    The disk drive of FIG. 1 comprises a digital recording signal processing unit  30   a  for converting input data into record-formatted EFM (Eight to Fifteen Modulation) data while adding additional data such as error correction codes (ECC); a channel bit encoder  40  for converting the record-formatted data into writing signals; an optical driver  41  for generating signals to drive an LD (Laser Diode); an optical pickup  20  for writing signals onto the surface of a writable disk  10  and for reading written signals from the surface of the optical disk  10 ; an R/F unit  50  for producing binarized signals and TE (Tracking Error) and FE (Focusing Error) signals through filtering and combining the signals detected by the pickup  20 ; an ATIP decoder  51  for producing ATIP (Absolute Time In Pregroove) frames by decoding a wobble signal detected from the writable disk  10 ; a driving unit  70  for driving a sled motor  11   b  to move the optical pickup  20  and a spindle motor  11   a  to rotate the disk  10 ; a servo unit  60  for conducting the tracking/focusing operation of an objective lens in the pickup  20  and controlling the driving unit  70  to rotate the disk  10  at a constant speed; a digital reproduced signal processing unit  30   b  for restoring original data from the binarized signals using a self clock synchronized with the binarized signals in phase; and a microcomputer  80  for controlling an overall recording/reproducing operation, especially, for adjusting writing features of the optical driver  41  with reference to write strategies classified by disk conditions stored in an internal ROM  81 .  
         [0023]    [0023]FIG. 2 is a flow chart of the first embodiment of a data recording method in accordance with the present invention. The flow chart of FIG. 2 conducted by the disk drive structure in FIG. 1 is explained in detail below.  
         [0024]    It is supposed in the following explanation that the internal ROM  81  of the microcomputer  80  stores information about write strategies for every disk manufacturing company.  
         [0025]    If a write-once disk such as a CD-R is normally placed in the disk drive (S 10 ) it is rotated at a constant speed under control of the microcomputer  80 . Afterwards, the microcomputer  80  analyses ATIP frames outputted from the ATIP decoder  51  to search frames decoded from a lead-in area for the 11th (Frame No. N+10) and the 21st (Frame No. N+20) frame, namely, the second and the third special information. Each ATIP frame is composed of three bytes called ‘Minutes’, ‘Seconds’ and ‘Frames’, respectively. Respective MSBs of three bytes of the two frames are ‘ 110 ’ and ‘ 111 ’, respectively. The 11th frame includes information on the start time of a lead-in area while the 21st frame includes information on the start time of a lead-out area.  
         [0026]    If the two frames are found, the microcomputer  80  reads out respective values written therein (S 11 ). At this time, the microcomputer  80  replaces three bits of M 1 :S 1 :F 1  with ‘ 100 ’ for the 11th frame and with ‘ 000 ’ for the 21st frame, respectively.  
         [0027]    The start time written in the 11th frame has a different value if a manufacturing company is different. Therefore, the microcomputer  80  can identify which company has manufactured the inserted disk  10  based on the read-out start time. From the third special information, the microcomputer  80  knows storage capacity of the disk  10 . For example, if three bytes of the third special information is ‘ 0111   0000 ,  0100   0101 ,  0001   0101 ’, it means that the start time (location) is 70 minutes and 45 seconds and 15 frames because each byte is encoded in BCD (Binary Coded Decimal).  
         [0028]    The microcomputer  80  knows the storage capacity from the start time of a lead-out area written in the 21st frame and, then calculates track pitch using a well-known equation and the known storage capacity (S 12 ). If the known storage capacity is 74 minutes the track pitch calculation results in the standard value, namely, about 1.6 μm, however, if it is longer than 74 minutes, the calculation results in a narrower pitch than the standard. The microcomputer  80  selects a write strategy stored in the internal ROM  81  based on the identified company of the disk  10  (S 13 ).  
         [0029]    Afterwards, if data recording is requested (S 20 ), the microcomputer  80  checks the calculated track pitch, and, in case that the pitch is standard (about 1.6 μm), it adjusts the level and/or width of writing pulses according to the selected write strategy while recording input data onto the disk  10  (S 22 ). The writing pulses have an optimal writing power determined beforehand through conducting an OPC.  
         [0030]    When data is recorded, input data is encoded with parity by the digital recording signal processing unit  30   a  to form ECC blocks to improve reliability of data recording/reproduction. Each ECC block is outputted in EFM-formatted serial bits from the digital recording signal processing unit  30   a  to the channel bit encoder  40  that modulates the serial bits into NRZ signals. The optical driver  41  outputs PWM (Pulse-Width Modulated) writing signals according to the modulated NRZ signals while adjusting the level and/or width of the PWM signal in accordance with the selected write strategy. The outputs of the optical driver  41  are converted by the optical pickup  20  to light beams that form respective marks and spaces along a track of the writable disk  10 .  
         [0031]    However, if the calculated track pitch is narrower than the standard (S 21 ), the microcomputer  80  sets the optical driver  41  to make the width of each writing pulse inversely proportional to the track pitch, while maintaining the level of each pulse as defined in the selected write strategy. The level of each pulse may be lowered based on the difference between the calculated pitch and the standard.  
         [0032]    The adjusting rate (Δ) can be given by an equation of Δ=k×1.6 um/‘the calculated pitch’ where k is a proportional constant. Instead of calculating track pitch, the adjusting rate (Δ) can be directly determined by an equation of Δ=k′×‘the detected disk capacity’/74 minutes where k′ is a proportional constant, after the storage capacity is known.  
         [0033]    [0033]FIG. 3 shows an example in which the pulse duration is increased according to the manner explained above. The adjusting rate (Δ) may be applied to all writing pulses nT equally or differently. In case that different adjusting rates are applied, Δ is applied for 3T, αΔ for 4T, 2αΔ for 5T, and so on. The constant α is chosen through many experiments.  
         [0034]    The optical driver  41  outputs PWM signals made from input data that are adjusted in their duration, for example, as illustrated in FIG. 3. The outputted PWM signals are then written onto the writable disk  10  through the optical pickup  20  (S 23 ).  
         [0035]    This writing process continues until the completion of the data record (S 24 ).  
         [0036]    [0036]FIG. 4 is a flow chart of the second embodiment of a data recording method in accordance with the present invention.  
         [0037]    For the second embodiment, the internal ROM  81  of the microcomputer  80  stores adjusting coefficients (α k ) for a non-standard capacity disk as well as information about width Ti of each pulse kT for a standard capacity disk of every disk manufacturing company. The adjusting coefficients (α k ) are also chosen through many experiments. An adjusting coefficient for a long pulse is greater than a coefficient for a short pulse, namely, α k &lt;α k+1 . FIG. 5 illustrates information stored in the microcomputer  80 .  
         [0038]    When the disk  10  is normally placed in the disk drive of FIG. 1 (S 30 ), the microcomputer  80  rotates the disk  10  while analyzing ATIP frames outputted from the ATIP decoder  51 . Based on the analyzed ATIP information, the microcomputer  80  identifies the disk manufacturer and the disk capacity as aforementioned in the first embodiment (S 31 ). After the identification, the microcomputer  80  selects a write strategy suitable to the identified manufacturer from the internal ROM  81  (S 32 ).  
         [0039]    Afterwards, if data recordation is requested (S 40 ), the microcomputer  80  checks the identified disk capacity, and, in case that the disk capacity is about 80 minutes (S 41 ) longer than the standard, it continues to check whether a current recording position crosses over a certain limit point, e.g., ⅔ of radius of the disk  10 . A radial position of the current recording position can be known through inserting an absolute time, written in fields of MIN:SEC:FRAME of each analyzed ATIP frame into a well-known equation.  
         [0040]    If the current position has not reached the limit point yet, the microcomputer  80  conducts data recording while adjusting writing pulses having an optimal writing power on a basis of the selected write strategy (S 44 ). If the current position is beyond the limit point, the microcomputer  80  reads each pulse width (T k ) and each adjusting coefficient (α k ) therefor from the ROM  81 , and calculates each pulse duration by multiplying T k  by α k . The calculated duration for each pulse nT is set to the optical driver  41  by the microcomputer  80 .  
         [0041]    The PWM signals of the optical driver  41  are adjusted in their duration by the setting and are then written onto the writable disk  10  through the optical pickup  20  (S 43 ). This writing process continues until completion of data recording (S 50 ).  
         [0042]    If the identified storage capacity is standard, namely, 74 minutes, the microcomputer  80  conducts data record while adjusting writing pulses on a basis of the selected write strategy as mentioned before (S 44 ).  
         [0043]    The above-explained data recording method can improve data quality during later reproduction even though it is recorded onto a non-standard disk that is larger in capacity than the standard.  
         [0044]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.