Backlight controller for driving light sources

Abstract

A backlight controller for driving a plurality of light source strings includes a feedback circuitry, a phase array circuitry, and an encoder circuitry. The feedback circuitry is coupled to the plurality of light source strings and generates a plurality of feedback signals indicative of a plurality of currents flowing through the plurality of light source strings respectively. The phase array circuitry receives a dimming control signal and receives a code signal indicative of a total number of operative light source strings among the plurality of light source strings, and generates a plurality of phase shift signals according to the code signal and the dimming control signal. The encoder circuitry is coupled to the phase array circuitry and receives the plurality of phase shift signals and the plurality of feedback signals, and generates a plurality of pulse width modulation signals to respectively control the operative light source strings.

1 . A backlight controller for driving a plurality of light source strings, comprising:
 a feedback circuitry coupled to said plurality of light source strings and for generating a plurality of feedback signals indicative of a plurality of currents flowing through said plurality of light source strings respectively;   a phase array circuitry for receiving a dimming control signal and for receiving a code signal indicative of a total number of operative light source strings among said plurality of light source strings, and for generating a plurality of phase shift signals according to said code signal and said dimming control signal; and   an encoder circuitry coupled to said phase array circuitry and for receiving said plurality of phase shift signals and said plurality of feedback signals, and for generating a plurality of pulse width modulation signals to respectively control said operative light source strings.   
   
   
       2 . The backlight controller as claimed in  claim 1 , wherein each light source string of said plurality of light source strings comprises a plurality of light emitting diodes in series. 
   
   
       3 . The backlight controller as claimed in  claim 1 , further comprising:
 a phase number encoder for receiving said plurality of feedback signals from said feedback circuitry and for generating said code signal according to said plurality of feedback signals.   
   
   
       4 . The backlight controller as claimed in  claim 3 , wherein said encoder circuitry comprises a multiplexer coupled to said phase number encoder and for receiving said plurality of phase shift signals and said plurality of feedback signals, and for generating said plurality of pulse width modulation signals. 
   
   
       5 . The backlight controller as claimed in  claim 1 , wherein said feedback circuitry is capable of comparing each feedback signal of said plurality of feedback signals to a predetermined reference signal, and is capable of adjusting said plurality of currents according to a result of said comparison. 
   
   
       6 . The backlight controller as claimed in  claim 1 , wherein said encoder circuitry is capable of comparing each feedback signal of said plurality of feedback signals to a predetermined reference signal, and is capable of generating a plurality of status indication signals indicating which light source string among said plurality of light source strings is operative. 
   
   
       7 . The backlight controller as claimed in  claim 1 , wherein a phase shift between two phase shift signals of said plurality of phase shift signals is adjusted according to said total number of operative light source strings. 
   
   
       8 . The backlight controller as claimed in  claim 1 , wherein said dimming control signal comprises a pulse width modulation signal. 
   
   
       9 . The backlight controller as claimed in  claim 1 , wherein said dimming control signal comprises an analog voltage signal. 
   
   
       10 . The backlight controller as claimed in  claim 1 , wherein a total number of said plurality of phase shift signals is equal to said total number of operative light source strings. 
   
   
       11 . A method for driving a plurality of light source strings, comprising:
 receiving a plurality of feedback signals indicative of a plurality of currents flowing through said plurality of light source strings respectively;   generating a code signal indicative of a total number of operative light source strings among said plurality of light source strings according to said plurality of feedback signals;   generating a plurality of phase shift signals according to said code signal and a dimming control signal; and   generating a plurality of pulse width modulation signals according to said plurality of phase shift signals and said plurality of feedback signals.   
   
   
       12 . The method as claimed in  claim 11 , further comprising:
 respectively controlling said operative light source strings by said plurality of pulse width modulation signals.   
   
   
       13 . The method as claimed in  claim 11 , wherein each light source string of said plurality of light source strings comprises a plurality of light emitting diodes in series. 
   
   
       14 . The method as claimed in  claim 11 , further comprising:
 comparing each feedback signal of said plurality of feedback signals to a predetermined reference signal; and   generating a plurality of status indication signals indicating which light source string among said plurality of light source strings is operative.   
   
   
       15 . The method as claimed in  claim 11 , wherein said dimming control signal comprises a pulse width modulation signal. 
   
   
       16 . The method as claimed in  claim 11 , wherein said dimming control signal comprises an analog voltage signal. 
   
   
       17 . The method as claimed in  claim 11 , further comprising:
 adjusting a phase shift between two phase shift signals of said plurality of phase shift signals according to said total number of operative light source strings.   
   
   
       18 . The method as claimed in  claim 11 , further comprising:
 comparing each feedback signal of said plurality of feedback signals to a predetermined reference signal; and   adjusting said plurality of currents according to a result of said comparison.   
   
   
       19 . A display system comprising:
 a plurality of light source strings; and   a backlight controller for driving said plurality of light source strings, said backlight controller comprising:
 a feedback circuitry coupled to said plurality of light source strings and for generating a plurality of feedback signals indicative of a plurality of currents flowing through said plurality of light source strings respectively; 
 a phase array circuitry for receiving a dimming control signal and for receiving a code signal indicative of a total number of operative light source strings among said plurality of light source strings, and for generating a plurality of phase shift signals according to said code signal and said dimming control signal; and 
 an encoder circuitry coupled to said phase array circuitry and for receiving said plurality of phase shift signals and said plurality of feedback signals, and for generating a plurality of pulse width modulation signals to respectively control said operative light source strings. 
   
   
   
       20 . The display system as claimed in  claim 19 , wherein each light source string of said plurality of light source strings comprises a plurality of light emitting diodes in series. 
   
   
       21 . The display system as claimed in  claim 19 , further comprising:
 a phase number encoder for receiving said plurality of feedback signals from said feedback circuitry and for generating said code signal according to said plurality of feedback signals.   
   
   
       22 . The display system as claimed in  claim 21 , wherein said encoder circuitry comprises a multiplexer coupled to said phase number encoder and for receiving said plurality of phase shift signals and said plurality of feedback signals, and for generating said plurality of pulse width modulation signals. 
   
   
       23 . The display system as claimed in  claim 19 , wherein said feedback circuitry is capable of comparing each feedback signal of said plurality of feedback signals to a predetermined reference signal, and is capable of adjusting said plurality of currents according to a result of said comparison. 
   
   
       24 . The display system as claimed in  claim 19 , wherein said encoder circuitry is capable of comparing each feedback signal of said plurality of feedback signals to a predetermined reference signal, and is capable of generating a plurality of status indication signals indicating which light source string among said plurality of light source strings is operative. 
   
   
       25 . The display system as claimed in  claim 19 , wherein said dimming control signal comprises a pulse width modulation signal. 
   
   
       26 . The display system as claimed in  claim 19 , wherein said dimming control signal comprises an analog voltage signal. 
   
   
       27 . The display system as claimed in  claim 19 , wherein a phase shift between two phase shift signals of said plurality of phase shift signals is adjusted according to said total number of operative light source strings.