Patent ID: 8378586

Claim:
A backlight system for light emitting diodes (LEDs), the backlight system comprising: a controllable power source; a plurality of LED based luminaires arranged to receive power in parallel from said controllable power source; a plurality of driving circuitries, each of said plurality of driving circuitries arranged to control the light output of at least two of said plurality of LED based luminaires and further arranged to compare the voltage drops of said controlled at least two LED based luminaires and output information regarding the voltage drop of at least one of said at least two LED based luminaires controlled thereby responsive to said comparison; and a plurality of controllable dissipative elements, each of said plurality of controllable dissipative elements arranged in series with a unique one of said plurality of LED based luminaires, and wherein the output information is a function of the voltage at one end of the respective controllable dissipative element, wherein said controllable power source is arranged to output a voltage responsive to the output information and wherein either: said plurality of driving circuitries are connected in series, the output information of each driving circuitry comprises information regarding the voltage drop of at least one of said at least two LED based luminaires controlled thereby in relation to the output information received from a preceding serially connected driving circuitry; or the output information from said plurality of driving circuitries is connected in parallel to the controllable power source, wherein each of said plurality of LED based luminaires is constituted of an LED string, wherein each of said driving circuitries comprises a monitoring and control functionality arranged to: detect if any of the at least two LED based luminaires controlled thereby are inactive; and prevent said output information from reflecting the function of the voltage of the respective controllable dissipative element arranged in series with the inactive LED based luminaire controlled thereby.