Method and apparatus for generating the wobble clock signal

Abstract

A method for generating a wobble clock signal. When the wobble signal becomes deformed or a defect on the optical disc is found, the present invention provides a stable wobble clock signal, which is used to maintain a stable rotation speed when the optical disc is processed. In addition, the present invention also determines whether the wobble signal is deformed according to the result of comparing the width of the wobble signal at different status with the average of the half cycle width of the wobble signal.

1 - 20 . (canceled) 
   
   
       21 . An apparatus for generating a wobble clock signal, comprising:
 a selection circuit configured to receive a wobble signal from an optical disc, to receive the wobble clock signal from a clock signal generating circuit, receive a deformation enabling signal, and provide a selected signal selected from the wobble signal or the wobble clock signal based, at least in part, on the deformation enabling signal; and   the clock signal generating circuit configured to receive the selected signal and to generate the wobble clock signal according to the selected signal.   
   
   
       22 . The apparatus of  claim 21 , further comprising:
 a deformation detecting circuit configured to provide the deformation enabling signal according to a comparison of a width of the wobble signal to an average width of the selected signal.   
   
   
       23 . The apparatus of  claim 22 , wherein the deformation detecting circuit comprises:
 a first counter configured to count the width of the wobble signal; and   a comparator configured to generate comparison data according to a comparison of the count of the first counter to an indication of the average width of the selected signal and to provide a deformation signal according to whether the comparison data is within a predetermined range, wherein the deformation detecting circuit is further configured to provide the deformation enabling signal according to the deformation signal.   
   
   
       24 . The apparatus of  claim 23 , wherein the deformation detecting circuit further comprises:
 a deformation signal counting circuit configured to count a duration during which the deformation signal is continuously enabled and to provide the deformation enabling signal according to the counted duration.   
   
   
       25 . The apparatus of  claim 21 , wherein the clock signal generating circuit comprises:
 a second counter configured to count a width of the selected signal;   a low-pass filter configured to average the count of the second counter and to generate an average clock signal according to the averaged count; and   a clock signal output circuit configured to generate the wobble clock signal by dividing a frequency of the average clock signal by a positive integer.   
   
   
       26 . The apparatus of  claim 25 , wherein the clock generating circuit further comprises:
 an absolute-time in pregroove decoding circuit configured to decode absolute-time in pregroove data according to the count of the second counter and the averaged count.   
   
   
       27 . The apparatus of  claim 21 , wherein the selection circuit is further configured to select the selected signal based, in part, on a defect enabling signal indicative a detection of an optical disc defect. 
   
   
       28 . The apparatus of  claim 27 , wherein the selection circuit comprises:
 an OR gate configured to provide a multiplexer select signal according to a logical OR of the deformation enabling signal and the defect enabling signal; and   a multiplexer configured to receive the wobble signal, to receive the wobble clock signal, and to provide the selected signal according to the multiplexer select signal.   
   
   
       29 . The apparatus of  claim 21 , further comprising:
 a deglitch circuit configured to deglitch the wobble signal.   
   
   
       30 . A method for generating a wobble clock signal, comprising:
 providing a select signal based, at least in part, on a frequency difference between a wobble signal of an optical disc and an average frequency of a selected signal;   if the provided select signal is at a first state, providing the wobble signal as the selected signal;   if the provided select signal is at a second state, providing the wobble clock signal as the selected signal; and   generating the wobble clock signal according to the selected signal.   
   
   
       31 . The method of  claim 30 , wherein providing the select signal includes:
 counting a width of the selected signal;   determining an average width of the selected signal;   providing comparison data according to a comparison of the counted width to the determined average width; and   providing the select signal according to whether the comparison data is within a predetermined range.   
   
   
       32 . The method of  claim 31 , further comprising:
 counting a duration during which the comparison data is not within the predetermined range; and   providing the select signal according to the counted duration.   
   
   
       33 . The method of  claim 31 , wherein determining the average width includes:
 counting multiple widths of the selected signal; and   low-pass filtering the multiple counted widths.   
   
   
       34 . The method of  claim 30 , wherein generating the wobble clock signal includes:
 generating an average clock signal according to the average frequency of the selected signal; and   dividing a frequency of the average clock signal by a positive integer.   
   
   
       35 . The method of  claim 30 , wherein providing the select signal is further based on a defect enabling signal indicative of a detection of an optical disc defect. 
   
   
       36 . The method of  claim 30 , further comprising:
 decoding absolute-time in pregroove data according to the selected signal.   
   
   
       37 . The method of  claim 36 , further comprising:
 decoding absolute-time in pregroove data according to a difference between a frequency of the selected signal and the average frequency of the selected signal.   
   
   
       38 . A processor-readable medium storing instructions which, when executed by a processor, enable a method for generating a wobble clock signal, the method comprising:
 providing a select signal based, at least in part, on a difference between a width of a wobble signal of an optical disc and an average width of a selected signal;   if the provided select signal is at a first logic level, providing the selected signal according to the wobble signal;   if the provided select signal is at a second logic level, providing the selected signal according to the wobble clock signal; and   generating the wobble clock signal from the selected signal.   
   
   
       39 . The processor-readable medium of  claim 38 , wherein generating the wobble clock includes:
 counting a width of the selected signal;   providing count data according to a counted width of the selected signal;   providing an average clock signal according to low-pass filtering the count data; and   dividing a frequency of the average clock signal.   
   
   
       40 . The processor-readable medium of  claim 38 , wherein the method further comprises:
 decoding absolute-time in pregroove data according to a difference between a width of the selected signal and the average width of the selected signal.   
   
   
       41 . An apparatus for maintaining a stable rotation speed when processing an optical disc, comprising:
 means for selecting a select signal based, at least in part, on a frequency variation of a wobble signal of an optical disc;   means for providing the wobble signal as the selected signal while the provided select signal is at a first state;   means for providing the wobble clock signal as the selected signal while the provided select signal is at a second state; and   means for generating the wobble clock signal according to the selected signal.   
   
   
       42 . The apparatus of  claim 41 , wherein the frequency varation is a frequency difference between the wobble signal and an average frequency of the selected signal.