Color control for dynamic scanning backlight

A method of controlling the output of a luminaire comprising a plurality of LED strings, the method comprising:

• receiving a first target signal associated with a first frame;
• generating a plurality of pulse width modulated first light control signals for a portion of said first frame responsive to said received first target signal, said pulse width modulated first light output signals exhibiting a period and a respective first duty cycle for each of the plurality of LED strings;
• sampling a light output of the plurality of LED strings at discrete intervals during said portion of said first frame, the light output being responsive to said pulse width modulated first light control signals;
• averaging said samples of said first frame over at least one of said period;
• adjusting, during said first frame, said first duty cycle of at least one of said plurality of pulse width modulated first light control signals responsive to said averaging;
• receiving a second target signal associated with a second frame, said second frame following said first frame;
• comparing said received second target signal with a least one of said averages;
• and
• generating a plurality of pulse width modulated second light control signals for a portion of said second frame exhibiting said period and a respective second duty cycle for each of the plurality of LED strings, said second duty cycles being responsive to said comparing.

A backlight luminaire controller for a frame by frame changing target signal, the backlight luminaire controller comprising:

• a synchronizing controller;
• a difference circuit;
• a feedback controller responsive to said synchronizing controller and said difference circuit;
• a pulse width modulation (PWM) functionality exhibiting a duty cycle and a period, said duty cycle being responsive to said feedback controller;
• and
• an averager responsive to said feedback controller and operative to generate at least one average over an integer multiple of said period,
• said feedback controller operative responsive to said synchronizing controller to generate a duty cycle for the next frame responsive to at least one of said generated at least one average of the current frame and a received target signal of said next frame.

An apparatus for controlling a luminaire responsive to a target signal with a value changing on a frame by frame basis, the apparatus comprising:

• a feedback controller;
• a signal generator, responsive to said feedback controller and operative to generate a light control signal for an on time portion of a first frame responsive to a first frame target signal value;
• a sampler operative to sample a light output during said on time portion of the first frame, said light output being responsive to said generated light control signal of the first frame;
• and
• a difference circuit arranged to compare a second frame target signal value with said sampled light output of said on time portion of the first frame and generate an error signal responsive to said comparison,
• wherein said feedback controller is operative to control said signal generator to generate a light control signal for an on time portion of the second frame responsive to said error signal.