A method is set forth for automatically adjusting display brightness on a mobile electronic device having a light sensor, display screen and orientation sensor, for legibility under varying lighting conditions and orientations of the device. The method includes obtaining light level samples from the light sensor, and orientation from the orientation sensor, and adjusting backlight intensity of the display responsive to the light level samples and orientation of the device. Preferably, backlight adjustments are made from dim to bright notwithstanding orientation of the device whereas adjustments from bright to dim are made only for orientations of the device where the light sensor is unlikely to be covered.