Apparatus having switchable servo gains and offsets for optical disk drive and method thereof

Abstract

An apparatus having switchable servo gains and offsets for an optical disk drive adjusts its gains and offsets through the coupling of a servo signal and a switch with several changeable paths. The servo signals are either designated to undergo signal reduction with respect to a first offset through the switch and then be output after a first gain unit performed proportional conversion, or designated to undergo signal reduction with respect to a second offset and then be output after a second gain unit performed proportional conversion. The switch is switched on/off in the light of the working status of the pick-up head, for example, seeking or tracking, at a data area or at a blank area, and at a groove area or at a land area, so as to choose different offsets and gains to have the conversion of the servo signals.

1 . A method for switching servo gains and offsets for an optical disk drive, the method comprising: 
 determining the location of a pick-up head on an optical disk having respective areas thereon with low and high reflective ratios;    outputting a signal obtained by multiplying a servo signal by a first gain if the pick-up head is at a location with a low reflective ratio on the optical disk; and    outputting a normalized signal obtained by multiplying the servo signal by a second gain smaller than the first gain if the pick-up head is at a location on the optical disk with a high reflective ratio.    
   
   
       2 . The method for switching servo gains and offsets for an optical disk drive of  claim 1 , wherein the servo signal is a TE signal or a FE signal.  
   
   
       3 . The method for switching servo gains and offsets for an optical disk drive of  claim 1 , wherein the outputted servo signal is from the conversion of the first gain when the pick-up head is in a blank area, and the outputted servo signal is from the conversion of the second gain when the pick-up head is in a data area.  
   
   
       4 . The method for switching servo gains and offsets for an optical disk drive of  claim 1 , wherein the outputted servo signal is from the conversion of the first gain when the pick-up head is in a groove area, and the outputted servo signal is from the conversion of the second gain when the pick-up head is in a land area.  
   
   
       5 . The method for switching servo gains and offsets for an optical disk drive of  claim 1 , further comprising the step of: 
 determining the values of a first offset, a second offset, a first gain unit and a second gain unit by means of on-line or off-line detecting the servo signal.    
   
   
       6 . A method for switching servo gains and offsets for an optical disk drive, the method comprising: 
 determining the location of a pick-up head on an optical disk based upon a reflective ratio on the optical disk;    outputting a signal after converting a servo signal by a first gain if the pick-up head is in a tracking status; and    outputting a normalized signal with respect to a level of the converted servo signal by multiplying the servo signal by a second gain less than the first gain if the pick-up head is in a seeking status.    
   
   
       7 . The method for switching servo gains and offsets for an optical disk drive of  claim 6 , further comprising the step of: 
 determining the values of offsets, the first gain and the second gain by means of on-line detecting the servo signal.    
   
   
       8 . The method for switching servo gains and offsets for an optical disk drive of  claim 6 , further comprising the step of: 
 determining the values of offsets, the first gain and the second gain by means of off-line detecting the servo signal.    
   
   
       9 . A method for switching servo gains and offsets for an optical disk drive, the method comprising: 
 determining a working status of a pick-up head based upon a reflective ratio on the optical disk; and    selectively processing a servo signal from the pick-up head in response to the determined working status of the pick-up head,    wherein the servo signal is amplified by a first gain when the pick-up head is in a tracking status and the servo signal is amplified by a second gain less than the first gain when the pick-up head is in a seeking status.    
   
   
       10 . The method of  claim 9 , further comprising outputting a normalized control signal comprising the servo signal amplified by the second gain when the pick-up head is in a seeking status.  
   
   
       11 . The method of  claim 10 , further comprising driving the pick-up head by using the normalized control signal.  
   
   
       12 . The method of  claim 9 , further comprising outputting a control signal comprising the servo signal amplified by the first gain when the pick-up head is in a tracking status.  
   
   
       13 . The method of  claim 9 , further comprising selectively adding an offset to the servo signal in response to the determined working status of the pick-up head.  
   
   
       14 . An apparatus having switchable servo gains and offsets for an optical disk drive, comprising: 
 means for determining the location of a pick-up head on an optical disk having respective areas thereon with low and high reflective ratios;    means for outputting a signal obtained by multiplying a servo signal by a first gain if the pick-up head is at a location with a low reflective ratio on the optical disk; and    means for outputting a normalized signal obtained by multiplying the servo signal by a second gain smaller than the first gain if the pick-up head is at a location on the optical disk with a high reflective ratio.    
   
   
       15 . The apparatus having switchable servo gains and offsets for an optical disk drive of  claim 14 , wherein the servo signal is a TE signal or a FE signal.  
   
   
       16 . The apparatus having switchable servo gains and offsets for an optical disk drive of  claim 14 , wherein the outputted servo signal is from the conversion of the first gain when the pick-up head is in a blank area, and the outputted servo signal is from the conversion of the second gain when the pick-up head is in a data area.  
   
   
       17 . The apparatus having switchable servo gains and offsets for an optical disk drive of  claim 14 , wherein the outputted servo signal is from the conversion of the first gain when the pick-up head is in a groove area, and the outputted servo signal is from the conversion of the second gain when the pick-up head is in a land area.  
   
   
       18 . The apparatus having switchable servo gains and offsets for an optical disk drive of  claim 14 , further comprising means for determining the values of a first offset, a second offset, a first gain unit and a second gain unit by means of on-line or off-line detecting the servo signal.  
   
   
       19 . An apparatus having switchable servo gains and offsets for an optical disk drive, comprising: 
 means for determining the location of a pick-up head on an optical disk based upon a reflective ratio on the optical disk;    means for outputting a signal after converting a servo signal by a first gain if the pick-up head is in a tracking status; and    means for outputting a normalized signal with respect to a level of the converted servo signal by multiplying the servo signal by a second gain less than the first gain if the pick-up head is in a seeking status.    
   
   
       20 . The apparatus having switchable servo gains and offsets for an optical disk drive of  claim 19 , further comprising means for determining the values of offsets, the first gain and the second gain by means of on-line detecting the servo signal.  
   
   
       21 . The apparatus having switchable servo gains and offsets for an optical disk drive of  claim 19 , further comprising means for determining the values of offsets, the first gain and the second gain by means of off-line detecting the servo signal.