Patent ID: 9019194
Filing Date: 2015-04-28
Classification: G09G

Abstract:
1. A liquid crystal display (LCD) comprising: a liquid crystal display panel configured to display modulated data based on a frame frequency; light sources configured to generate light to be irradiated into the liquid crystal display panel; a scanning backlight controller configured to calculate a turn-on duty ratio of a pulse width modulation (PWM) signal for controlling turn-on and turn-off operations of the light sources a light source driver configured to synchronize a frequency of the PWM signal with the frame frequency or with a frequency, that is two times faster than the frame frequency, based on the result of a comparison between the turn-on duty ratio of the PWM signal and a previously determined critical value and then sequentially drive the light sources along a data scanning direction of the liquid crystal display panel, wherein the scanning backlight controller includes: an input image analysis unit configured to analyze an input image and compute a frame representative value; a duty ratio calculation unit configured to calculate the turn-on duty ratio of the PWM signal based on the frame representative value; and a data modulation unit configured to stretch data of the input image based on the frame representative value, so as to compensate for a sudden change in a luminance depending on the turn-on duty ratio of the PWM signal, and generate the modulated data; wherein the input image analysis unit computes a histogram of the data of the input image and calculates the frame representative value of the histogram, the input image analysis unit determines a gain value depending on the frame representative value and supplies the gain value to the duty ratio calculation unit and the data modulation unit, wherein the gain value increases as the frame representative value increases, and decreases as the frame representative value decreases.