Patent ID: 6977642
Filing Date: 2005-12-20
Classification: G02B,G02F,G09G

Abstract:
1. A back light comprising: a plurality of light sources; a brightness control circuit for selecting and adjusting at least one of a plurality of light volume adjusting signals, and fixing output of the rest of said light volume adjusting signals according to a luminance adjusting signal when said luminance adjusting signal changes, said light volume adjusting signals being for adjusting said light sources in luminance, respectively, said luminance adjusting signal being for adjusting a total luminance of said light sources; and a plurality of lighting control circuits corresponding to said plurality of light sources, respectively, for receiving said light volume adjusting signals and adjusting voltage waveforms to be applied to said light sources according to the received light volume adjusting signals, respectively, wherein said brightness control circuit comprises: a detecting part for outputting a detecting signal when a luminance of one of said light sources corresponding to a selected light volume adjusting signal reaches a minimum luminance; and an adjusting part for successively performing a luminance-down operation, a turn-off operation, and a selecting operation while a luminance indicated by said luminance adjusting signal is smaller than an actual total luminance of said light sources, said luminance-down operation being for changing said selected light volume adjusting signal to lower luminances of the respective light sources, said turn-off operation being for fixing said selected light volume adjusting signal to a turn-off level of said light sources in response to said detecting signal, said selecting operation being for selecting anew, in response to said detecting signal, another one of said light volume adjusting signals corresponding to a light source which is lit.