Analysis of Flicker Phenomenon in TFT Module

Posted by sere on December 15th, 2020

FLICKER, commonly known as the forehead pattern, is a kind of splash screen we often encounter. In an ideal state, the center value of Vcom is consistent with the center value of Vpixel, and the difference between VpixelH and VpixelL is consistent with the difference between VcomH and VcomL. In this case, the TFT module will not appear flickering. When the center value or the difference of these two voltages deviates, the TFT module will appear flickering. For the TFT module splash screen, if line inversion is used, the phenomenon is as follows: When the display module is shaken up and down, many horizontal stripes will appear, but after stopping the shaking, the horizontal stripes will decrease or disappear, which is most obvious in grayscale. If frame inversion is used, the phenomenon is a splash screen with light and dark changes in the entire screen. For TFT lcd module flicker, the improvement method is to adjust the voltage Vcom of the common electrode.

By adjusting the values of Vcom and VcomH together, try to adjust which direction can make the FLICKER lighter, and finally determine the best effect of a specific value. However, because the values of Vcom and VcomH are jumping rather than continuously changing, sometimes the TFT lcd module FLICKER can only be adjusted to a very unobvious state, but it cannot be completely resolved. If the customer is not satisfied, he can try to adjust GAMMA or change to frame inversion mode. Because the human eye cannot distinguish a splash screen greater than 100 Hz, the slight FLICKER of the TFT module cannot be distinguished in this mode.

For fixed integrated circuits, the values of Vcom and VcomH are not fixed. The matching Panel is different. Different VDD voltages provided by customers and changes in GAMMA values will have an impact on Vpixel, resulting in TFT module FLICKER. At this time, it is necessary to readjust the values of Vcom and VcomH to eliminate the TFT module FLICKER.

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