Device and method for calibrating linear velocity and track pitch for optical disc

Abstract

A device and method for calibrating linear velocity and track pitch for an optical disc is disclosed. The device comprises a frequency divider, a synchronous bit-clock generator, a counter and a linear velocity and track pitch calculator. The frequency divider receives a motor frequency generator (FG) pulse and generates a motor rotation period signal (FG/X). The synchronous bit-clock generator generates a high frequency bit-clock according to a reproduced signal read from disc. The bit counter counts the pulse of the bit-clock for each period of the motor rotation period signal to generate the data amount M. The linear velocity and track pitch calculator calculates the linear velocity by a linear velocity function with the information of the data amount M and the motor rotation period. Then, the linear velocity and track pitch calculator calculates the track pitch by a pitch function with the information of the data amount, radius and linear velocity at different tracks.

1 . A calibration device for calibrating a linear velocity and a track pitch for an optical disc drive, comprising: 
 a bit-clock generator for generating a bit-clock signal having a frequency higher than that of a reproduced signal according to the reproduced signal read from an optical recording medium;    a data amount counting unit for counting the pulses of the bit-clock signal for each motor frequency generator pulse to generate a data amount; and    a calculator for calculating the linear velocity and the track pitch of the optical recording medium according to the data amount and the motor frequency generator pulse.    
   
   
       2 . The calibration device according to  claim 1 , further comprising a frequency divider for receiving an output pulse from a spindle motor to generate the motor frequency generator pulse according to a setting value.  
   
   
       3 . The calibration device according to  claim 1 , wherein the data amount counting unit is a counter.  
   
   
       4 . The calibration device according to  claim 1 , wherein the bit-clock generator comprises: 
 a feature extractor for determining the type of the optical recording medium according to the reproduced signal, and outputting a reference signal; and    a phase-locked loop circuit for outputting the bit-clock signal according to the reference signal.    
   
   
       5 . The calibration device according to  claim 2 , wherein the bit-clock generator comprises: 
 a feature extractor for determining the type of the optical recording medium according to the reproduced signal, and outputting a feedback signal;    a phase-locked loop circuit for receiving the feedback signal from the feature extractor and a constant-frequency pulse, and generating a control signal;    a control unit for controlling the rotation speeds of the spindle motor and the disc according to the control signal from the phase-locked loop circuit; and    an RF signal generator for generating the reproduced signal of the disc.    
   
   
       6 . The calibration device according to  claim 4 , wherein the reproduced signal is an EFM sync signal, an ATIP signal or a wobble signal.  
   
   
       7 . The calibration device according to  claim 5 , wherein the reproduced signal is an EFM sync signal, an ATIP signal or a wobble signal.  
   
   
       8 . The calibration device according to  claim 2 , wherein the calculator calculates the linear velocity β according to the following equation:  
     
       
         
           
             
               
                 
                   X 
                   Y 
                 
                 × 
                 
                   
                     2 
                     · 
                     π 
                     · 
                     R 
                   
                   β 
                 
                 × 
                 C 
               
               = 
               M 
             
             , 
           
         
       
       wherein Y represents the pulse number per revolution of the spindle motor, X is a frequency divisor of the motor frequency generator pulse, M is the data amount measured from the counter, R represents the radius of the position where an optical pick-up located on the optical recording medium, and C represents a bit-clock amount contained in the optical recording medium per unit time.  
     
   
   
       9 . The calibration device according to  claim 8 , wherein the position of the radius R is a position of 0th minute, 2nd second and 0th block, and R=25 mm.  
   
   
       10 . The calibration device according to  claim 8 , wherein the calculator calculates the track pitch t according to the following eqution:  
     
       
         
           
             
               t 
               = 
               
                 
                   
                     75 
                     ⁢ 
                     π 
                   
                   
                     n 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     β 
                   
                 
                 · 
                 
                   ( 
                   
                     
                       
                         ( 
                         
                           
                             M 
                             2 
                           
                           
                             M 
                             1 
                           
                         
                         ) 
                       
                       2 
                     
                     - 
                     1 
                   
                   ) 
                 
                 · 
                 
                   R 
                   1 
                   2 
                 
               
             
             , 
           
         
       
       wherein n represents the number of data blocks passed after any K tracks are jumped, 75 represents the number of data blocks contained in one second, R 1  represents a first radius of the optical pick-up, M 1  represents a first data amount, and M 2  represents a second data amount.  
     
   
   
       11 . The calibration device according to  claim 10 , wherein the position of the radius R is a position of 0th minute, 2nd second and 0th block, and R=25 mm.  
   
   
       12 . A method for calibration a linear velocity and a track pitch for an optical disc drive, comprising the steps of: 
 initializing the optical disc drive;    determining the type of the optical recording medium;    moving a pick-up to a lead-in area;    comparing a frequency generator pulse of the motor with a reproduced signal of the optical recording medium so as to get a value of a first data amount;    calculating the linear velocity of the optical recording medium according to the value of the first data amount and a calculation equation;    calculating the number of data blocks passed after any tracks are jumped, and getting a value of a second data amount of the tracks; and    calculating the track pitch t according to the linear velocity of the optical recording medium, the value of the second data amount, and a track-jumping equation.    
   
   
       13 . The method according to  claim 12 , wherein the step of initializing the optical disc drive comprises the following steps of: 
 moving the pick-up to the lead-in area;    activating a laser beam and focusing the laser beam;    setting a rotation control mode for the motor; and    positioning a track and reading the reproduced signal on the disc.    
   
   
       14 . The method according to  claim 12 , wherein the equation for calculating the linear velocity β is:  
     
       
         
           
             
               
                 
                   X 
                   Y 
                 
                 × 
                 
                   
                     2 
                     · 
                     π 
                     · 
                     R 
                   
                   β 
                 
                 × 
                 C 
               
               = 
               M 
             
             , 
           
         
       
       wherein Y represents the pulse number generated after the motor rotates a revolution, X is a frequency divisor of the motor frequency generator pulse, M is a value of the data amount, R represents the radius of the position where an optical pick-up located on the optical recording medium, and C represents a bit-clock amount contained in the optical recording medium per unit time.  
     
   
   
       15 . The method according to  claim 12 , wherein the equation for calculating the track pitch is:  
     
       
         
           
             
               t 
               = 
               
                 
                   
                     75 
                     ⁢ 
                     π 
                   
                   
                     n 
                     ⁢ 
                     
                         
                     
                     ⁢ 
                     β 
                   
                 
                 · 
                 
                   ( 
                   
                     
                       
                         ( 
                         
                           
                             M 
                             2 
                           
                           
                             M 
                             1 
                           
                         
                         ) 
                       
                       2 
                     
                     - 
                     1 
                   
                   ) 
                 
                 · 
                 
                   R 
                   1 
                   2 
                 
               
             
             , 
           
         
       
       wherein n represents the number of data blocks that are jumped, 75 represents the number of data blocks contained in one second, R 1  represents a first radius of the position of the pick-up when the pick-up starts, M 1  represents a first calculated data amount, and M 2  represents a second calculated data amount.  
     
   
   
       16 . The method according to  claim 15 , wherein the position of the radius R is a position of 0th minute, 2nd second and 0th block, and R=25 mm.  
   
   
       17 . The method according to  claim 12 , wherein the reproduced signal includes an EFM sync signal, an ATIP signal or a wobble signal.