Patent ID: 6812649
Filing Date: 2004-11-02
Classification: H05B

Abstract:
A system that uses both light from a backlight device and ambient light to display signals on a screen, comprising:a display device; a backlight device that is capable of providing light to the display device; a light-sensor, wherein the light sensor detects intensity of the ambient light; a power supply that selects either a battery or an external power source as a power source to provide driving power of the backlight device; a power source detector that detects the power source that provides the driving power of the backlight device; and a backlight control device coupled to the light-sensor and the power source detector that controls the power supply to apply a backlight driving current within a selected one of a plurality of backlight control ranges, wherein the plurality of backlight control ranges are different according to each of a detected ambient light intensity and the power source, wherein first and second backlight control ranges of the backlight control ranges are selected when the battery is selected.