Patent ID: 7952555
Filing Date: 2011-05-31
Classification: G09G

Abstract:
1. A luminance control method for a liquid crystal display device, which comprises a liquid crystal panel, a backlight disposed at the back of the liquid crystal panel and a luminance detecting unit for detecting a luminance of the backlight, for controlling an input level of a video signal to be inputted into the liquid crystal panel to control transmittance of the liquid crystal panel and provide a gray-level display, comprising performing, at a time before actually displaying an image, the steps of: measuring a luminance of light emitted from the backlight through the liquid crystal panel in a plurality of states where the liquid crystal panel has a predetermined transmittance and the backlight has a different luminance, and preliminarily storing the measured luminance of light emitted through the liquid crystal panel as associated with the luminance of the backlight detected by the luminance detecting unit for each of the plurality of states, respectively; and measuring a luminance of light emitted through the liquid crystal panel in each input level, and preliminarily storing the measured luminance associated with an input level which gives the luminance; and subsequently performing, at a time of actually displaying the image, the steps of: setting a desired luminance set value of light emitted through the liquid crystal panel in a state where the liquid crystal panel has a predetermined transmittance, calculating a luminance of the backlight to be detected by the luminance detecting unit which results in the set desired luminance set value of light emitted through the liquid crystal panel, on the basis of the preliminarily stored luminance association in each state; controlling the luminance of the backlight so as to be the calculated luminance; calculating a luminance of light emitted through the liquid crystal panel in each input level and a luminance to be set in each gray level in a case of the luminance set value, on the basis of the stored luminance and input level; extracting an input level, which gives a luminance substantially equal to the luminance to be set in each gray level, on the basis of the luminance in each calculated input level and the luminance to be set in each gray level, and storing the extracted input level associated with a gray level; and controlling the transmittance of the liquid crystal panel in a gray level associated with the input level of the video signal.