Analytic solution to remove flickers on a liquid crystal display television

Flickers have been critical issues on liquid crystal displays (LCDs) which use a backlight unit (BLU) under a panel. The luminance modulation of the backlight and the transmittance of the panel are independently investigated in frequency domain to look for an analytic solution to remove flickers on the LCD panel. The transmittance of the panel depends on how to drive the LC molecules and how the LC molecules respond. We shows there are three frequency components caused by only the panel driving. It is shown that the flicker can be generated by the inter-modulation effect between two different frequency groups from the BLU and the panel. To remove flickers on LCD TV panels, the frequency of the PWM backlight signal should be carefully chosen so that the inter-modulation frequencies may be higher than 60 Hz. It is shown that it is impossible to perceive flickers on an LCDTV operating at 120 Hz refresh rate if the frequency of the PWM signal is 120 Hz or 180 Hz.