Patent ID: 7978159

Claim:
An organic light emitting diode display device, comprising: a brightness detector that calculates a maximum brightness value of each pixel using inputted image data of current frame; an adder that adds all maximum brightness values of each pixel which are detected by the brightness detector; an average value calculator that calculates an average brightness value of a current frame using an added value of maximum brightness values which are added by the adder; a gamma weight calculator that calculates a gamma reference voltage weight which is set to correspond to the calculated average brightness value among predetermined gamma reference voltage weights; and a gamma reference voltage generator that changes a gamma reference voltage step by step in accordance with a gamma reference voltage weight which is calculated by the gamma weight calculator, wherein the gamma weight calculator stores a predetermined look-up table where a gamma reference voltage weight, which maintains a gamma reference voltage, gamma reference voltage weights having gamma reference voltages, which are increased step by step, and gamma reference voltage weights having gamma reference voltages, which are decreased step by step, are set, and wherein the gamma weight calculator compares the calculated average brightness value of a current frame with a predetermined reference brightness value to calculate a gamma reference voltage weight, which is set to the predetermined look-up table, in accordance with the compared result, thereby supplying it to the gamma reference voltage generator.