Splash Phenomenon Analysis for TFT LCD

2019-10-22 17:44

During application of tft lcd panels, it may happen that the lcd can not work properly and there is splash phenomenon occurs. What is the reason for this phenomenon?
First of all, it may be FLICKER.

        FLICKER is widely known as head-up pattern, which is the most common splash phenomenon we ever met. Ideally, 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 FLICKER phenomenon does not apprear. The FLICKER phenomenon occurs when the center value or difference of the two voltages deviates.
For FLICKER, if you use line inversion, the phenomenon is as follows: take a display module up and down, there are many horizontal stripes,
and the horizontal stripes are reduced or disappeared after stopping the shaking, which is most obvious under the gray level. If frame inversion is used,
the phenomenon is that the entire screen has a splash screen with light and dark changes. For FLICKER, the improvement is to adjust the voltage Vcom of the common electrode.




 
       By adjusting the values ​​of Vcom and VcomH, the first attempt to adjust to which direction can make the FLICKER lighter, and finally determine the best effect on a particular value.
However, since the values ​​of Vcom and VcomH are adjusted to be hopping rather than continuously changing, sometimes FLICKER can only be adjusted to a very inconspicuous state and cannot be completely solved.
If the customer is not satisfied, try to adjust GAMMA or change it. Frame inversion mode, because the splash screen larger than 100Hz is indistinguishable, so the slight FLICKER can't be distinguished in this mode.
 
      For fixed ICs, the values ​​of Vcom and VcomH are not fixed.
The matching Panel is different. The difference between the customer's supply of VDD voltage and the change of GAMMA value will affect Vpixel,
which will lead to the generation of FLICKER. The values ​​of Vcom and VcomH need to be re-adjusted to eliminate FLICKER.