AN2686

Location of flicker in LCDs

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Location of flicker in LCDs

Due to the inversion as described in Section 1: The general principle of the LCD screen, the

voltage on VCOM is fixed and the voltage on the display electrode changes according to the

different gray scales. There are 256 gray scales (8 bits of color) in Figure 3. If we consider,

for example, the gray scale V0, in order to keep the V0 gray scale continuously displayed on

the panel, the voltage on the display electrode must be very high during one interval and

very low during another. In different frames, still using V0 as an example, the absolute

differential voltage of the display electrode and the VCOM is fixed. So the displayed gray

scale has not changed although the voltages on the two ends of Clc alternate. This is the

ideal case and is shown in Figure 3.

Figure 3.

VCOM at ideal position