Method of controlling backlight device and display apparatus using the same

A display apparatus comprising:

• a display panel divided into a plurality of dimming areas;
• a backlight device including a plurality of light source blocks, each having a plurality of light sources, wherein the plurality of light source blocks respectively correspond to the dimming areas;
• a dimming device outputting dimming signals using image signals provided to each of the dimming areas;
• and
• a light source driver outputting driving signals to the light source blocks based on the dimming signals, wherein the dimming device comprises:
• an average/maximum gray-scale value generator extracting a plurality of gray-scale values from the image signals, averaging the plurality of gray-scale values to generate average gray-scale values of the respective dimming areas, and extracting maximum values of the gray-scale values to generate maximum gray-scale values of the respective dimming areas;
• a comparing/checking part checking whether the average gray-scale values are within a first reference range and checking whether the maximum gray-scale values are within a second reference range;
• a representative brightness value deciding part selecting one from at least two parameters according to a checked result and determining representative brightness values corresponding to the dimming areas using the selected parameter;
• and
• a dimming signal generator outputting the dimming signals to determine the duty ratios of the light source blocks based on the representative brightness values,
• wherein the first reference range is determined based on an average value of the average gray-scale values and the second reference range is determined based on an average value of the maximum gray-scale values.