Display device including a white sub-pixel and method of driving the same

A method of driving a display device comprising a display panel comprising a plurality of pixels, each of the pixels formed of red, green, blue, and white sub-pixels, the method comprising:

• extracting, by a data mapping unit, a minimum value from red, green, and blue input color data;
• determining, by the data mapping unit, white output color data by multiplying the extracted minimum value with a gain ratio;
• determining, by the data mapping unit, red, green, and blue output color data by subtracting the white output color data from each of the red, green, and blue input color data;
• adaptively changing, by a gain adjustment unit, the gain ratio based on an image being displayed;
• determining, by the gain adjustment unit, the gain ratio based on an accumulated sum of color data for each of the red, green, blue, and white output color data, wherein the accumulated sum of color data for each of the red, green, blue and white output color data is the sum of the corresponding color data for all of the pixels of the display panel;
• calculating, by the gain adjustment unit, a red comparative value, a green comparative value, and a blue comparative value by multiplying corresponding weights with the accumulated sum of color data;
• calculating, by the gain adjustment unit, a white comparative value by using the accumulated sum of color data for the white output color data;
• determining, by the gain adjustment unit, the gain ratio by comparing the white comparative value with a sum of the three comparative values;
• and
• displaying, by a display panel, an image corresponding to the white output color data and the red, green, and blue output color data.

A display device comprising:

• a display panel comprising a plurality of unit pixels each formed of red, green, blue, and white sub-pixels;
• a data driver configured to supply one of four color data signals corresponding to red, green, blue, and white output color data to each of the plurality of unit pixels;
• a gate driver configured to supply a gate-on voltage to the plurality of unit pixels;
• and
• a time controller configured to control the data driver and the gate driver, and to supply the red, green, blue, and white output color data to the data driver, wherein the time controller comprises:
• a gain adjustment unit configured to:
• i) determine a minimum value from red, green, and blue input color data, and ii) determine the white output color data by multiplying the minimum value with a gain ratio that adaptively changes based on an image being displayed;
• and
• a data mapping unit configured to determine red, green, blue, and white output color data by subtracting the white output color data from the red, green, and blue input color data,
• wherein the gain adjustment unit is further configured to change the gain ratio based on an accumulated sum of color data for each of the red, green, blue, and white output color data,
• wherein the accumulated sum of color data for each of the red, green, blue and white output color data is the sum of the corresponding color data for all of the unit pixels of the display panel, and
• wherein the gain adjustment unit is further configured to i) calculate a red comparative value, a green comparative value, and a blue comparative value by multiplying corresponding weights with the accumulated sum of color data, ii) calculate a white comparative value by using the accumulated sum of color data for the white output color data, and iii) determine the gain ratio by comparing the white comparative value with a sum of the three comparative values.