Patent ID: 9001166
Filing Date: 2015-04-07
Classification: G09G

Abstract:
1. A video display device having a display panel that displays a video in accordance with a video signal and a backlight that uses LEDs as light sources for illuminating the display panel, the video display device controlling a light emission luminance of the LEDs, for each of regions obtained by dividing the backlight into a plurality of regions, based on a predetermined relationship between a gradation value of a video region corresponding to each of the regions obtained by the division and the light emission luminance of the LEDs, the video display device comprising: a first luminance adjusting portion that, if a gradation value of the video meets a predetermined condition, adjusts the light emission luminance of the LEDs such that a variation range of the light emission luminance of the LEDs in a first range, defined based on the predetermined condition, of the gradation value of the video region is smaller than a variation range of the light emission luminance of the LEDs defined based on the predetermined relationship; and a second luminance adjusting portion that adjusts the light emission luminance of the LEDs so as to be a smaller light emission luminance than a lower limit value of the light emission luminance of the LEDs adjusted by the first luminance adjusting portion in a second range smaller in value than the first range, wherein the predetermined condition is a condition that, when producing a frequency distribution of the gradation value of the video and extracting upper two gradation values having greater frequencies in a gradation range where the gradation value of the video is greater than the predetermined gradation value, a ratio of a sum of frequencies of the upper two gradation values to a sum of frequencies of the gradation values in the gradation range is greater than a predetermined ratio.