Method for determining relationship between difference of object lens location and driving control effort in optical storage device

Abstract

A method is used in an optical storage device having a pickup head. The pickup head includes an object lens, a first light source and a second light source. The object lens focuses the laser light generated by the first light source onto a first focal point or focuses the laser light generated by the second light source onto a second focusing point. A driving control effort is used to change the location of the object lens. The method includes the following steps: providing the driving control effort to move the object lens; measuring a first parameter when a signal reaches a first state; measuring a second parameter when the signal reaches a second state; and determining the relationship between the difference of object lens location and the driving control effort according to a predetermined distance, the first parameter, and the second parameter.

1 . A method used in an optical storage device comprising a pickup head, wherein the pickup head comprises an object lens and a light source, the object lens focuses laser light generated by the light source onto a focal point, a driving control effort is used to change the location of the object lens, and the method is used to determine a relationship between the difference of object lens location and the driving control effort, the method comprising:
 (a) providing the driving control effort to move the object lens;   (b) measuring a first parameter when a signal reaches a first state;   (c) measuring a second parameter when the signal reaches a second state; and   (d) determining the relationship between the difference of object lens location and the driving control effort according to a predetermined distance, the first parameter, and the second parameter.   
   
   
       2 . The method of  claim 1 , wherein in step (b), the signal reaches the first state means that the signal reaches a first specific value after passes through a predetermined threshold; and in step (c), the signal reaches the second state means that the signal reaches a second specific value after passes through the first specific value. 
   
   
       3 . The method of  claim 2 , wherein the first specific value is substantially a maximum value of the signal, and the second specific value is substantially a minimum value of the signal. 
   
   
       4 . The method of  claim 2 , wherein the first specific value is substantially a maximum value of the signal mathematically operated by a first factor, and the second specific value is substantially a minimum value of the signal mathematically operated by a second factor. 
   
   
       5 . The method of  claim 2 , wherein the first parameter is a first driving control effort value of the driving control effort when the signal reaches the first state; and the second parameter is a second driving control effort value of the driving control effort when the signal reaches the second state. 
   
   
       6 . The method of  claim 5 , wherein between step (b) and step (c) the focal point passes through a surface layer of an optical disc; and in step (d):
 the relationship between the difference of object lens location and the driving control effort is determined according to a function of the predetermined distance, a driving control effort difference;   wherein the driving control effort difference is a difference value between the second driving control effort value and the first driving control effort value.   
   
   
       7 . The method of  claim 5 , wherein between step (b) and step (c) the focal point passes through a reflective layer of an optical disc; and in step (d):
 the relationship between the difference of object lens location and the driving control effort is determined according to a function of the predetermined distance, a driving control effort difference and a reflective index;   wherein the driving control effort difference is a difference value between the second driving control effort value and the first driving control effort value.   
   
   
       8 . The method of  claim 2 , wherein the first parameter is a first time when the signal reaches the first state; the second parameter is a second time when the signal reaches the second state, and in step (a) the change rate of the driving control effort with respect to time is a first slope. 
   
   
       9 . The method of  claim 8 , wherein between step (b) and step (c) the focal point passes through a surface layer of an optical disc; and in step (d):
 the relationship between the difference of object lens location and the driving control effort is determined according to a function of the predetermined distance, a time difference and the first slope;   wherein the time difference is a difference value between the second time and the first time.   
   
   
       10 . The method of  claim 8 , wherein between step (b) and step (c) the focal point passes through a reflective layer of an optical disc; and in step (d):
 the relationship between the difference of object lens location and the driving control effort is determined according to a function of the predetermined distance, a time difference and a reflective index;   wherein the time difference is a difference value between the second time and the first time.   
   
   
       11 . The method of  claim 1 , wherein the signal is a servo control signal. 
   
   
       12 . The method of  claim 1 , wherein the predetermined distance is determined through experimental statistics. 
   
   
       13 . The method of  claim 1 , further comprising
 calibrating the optical storage device in accordance with the determined relationship between the difference of object lens location and the driving control effort.   
   
   
       14 . The method of  claim 1 , further comprising
 processing frequency response calibration in accordance with the determined relationship between the difference of object lens location and the driving control effort.