Conventional backlight dimming methods can hardly be used in edge type backlight LCD. In order to perform a power efficient backlight local dimming in LCD of mobile devices, a novel backlight module structure called partitioned light guide (PLG) was proposed. The PLG backlight module consists of independently controlled light sources, allowing the light luminance distribution to be controlled locally and efficiently. A PLG LCD prototype with white LEDs was built for evaluation. It was proved that local backlight dimming can be performed effectively in the edge type LCD. In addition, to compensate the backlight nonniformity which was caused by light leakage at the boundaries of PLG, an image distortion driven local dimming algorithm was proposed. Image distortion level of displayed image was selected by the user to determine how much compromise was made between power saving ratio and image quality. More simulations with RGB LED light sources showed the method can significantly improve the power efficiency of edge type backlight LCD, compared with global dimming method and SSC method.
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