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 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.   
     
     
         2 . The method for switching servo gains for an optical disk drive of  claim 1 , further comprising the step of:
 determining the values of the first gain and the second gain by means of on-line detecting the servo signal.   
     
     
         3 . The method for switching servo gains for an optical disk drive of  claim 2 , further comprising the step of:
 determining the values of the first gain and the second gain by means of off-line detecting the servo signal.   
     
     
         4 . A method for switching servo gains 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.   
     
     
         5 . The method of  claim 4 , 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. 
     
     
         6 . The method of  claim 5 , further comprising driving the pick-up head by using the normalized control signal. 
     
     
         7 . The method of  claim 4 , 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. 
     
     
         8 . The method of  claim 4 , further comprising selectively adding an offset to the servo signal in response to the determined working status of the pick-up head. 
     
     
         9 . A method for switching servo 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 offset 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 offset less than the first offset if the pick-up head is in a seeking status.   
     
     
         10 . The method for switching servo offsets for an optical disk drive of  claim 9 , further comprising the step of:
 determining the values of the first offset and the second offset by means of on-line detecting the servo signal.   
     
     
         11 . The method for switching servo offsets for an optical disk drive of  claim 10 , further comprising the step of:
 determining the values of the first offset and the second offset by means of off-line detecting the servo signal.   
     
     
         12 . A method for switching servo 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 offset when the pick-up head is in a tracking status and the servo signal is amplified by a second offset less than the first offset when the pick-up head is in a seeking status.   
     
     
         13 . The method of  claim 12 , further comprising outputting a normalized control signal comprising the servo signal amplified by the second offset when the pick-up head is in a seeking status. 
     
     
         14 . The method of  claim 13 , further comprising driving the pick-up head by using the normalized control signal. 
     
     
         15 . The method of  claim 12 , further comprising outputting a control signal comprising the servo signal amplified by the first offset when the pick-up head is in a tracking status. 
     
     
         16 . The method of  claim 12 , further comprising selectively adding an offset to the servo signal in response to the determined working status of the pick-up head.