Patent ID: 8279214

Claim:
Apparatus for power level control in a display device having a plurality of luminous elements corresponding to the pixels of a picture, wherein the time duration of a video frame is divided into a plurality of subfields during which each luminous element can be activated for light emission in small pulses, called hereinafter sustain pulses, corresponding to a subfield code word representative of the video level of the corresponding pixel, wherein a set of power level modes is provided for subfield coding wherein to each power level mode a characteristic subfield organization belongs, the subfield organizations being variable in respect to the number of sustain pulses during a frame, said apparatus comprising a first circuit for transforming the power value of the picture to be displayed into a first number of sustain pulses, a second circuit for transforming the maximum video value into a gain value to be applied to the video levels of said picture, a third circuit for multiplying said first number of sustain pulses by the ratio of said maximum video value to a nominal value and delivering a second number of sustain pulses and a fourth circuit for transforming said second number of sustain pulses into a power level mode having a reduced number of sustain pulses such that the light emission of each pixel is kept the same.