In some LCD TFT applications, the display runs presenting a fixed image for a long time. The result of such performance may be the “ghost” image remaining on the screen.
What is that ghost image and why does it occur? Today we will focus on how to avoid and fix such an effect.
Why does the LCD ghosting happen?
Image persistence (or ghosting) on LCD TFT is a result of continuous displaying of static graphics on the screen for extended time periods. Such a performance make the TN crystals to generate the specific required color. In time, the TN crystals tend to “remember” their position.
When a different image starts to display, the crystals are stuck in their memorized position. This is an LCD ghosting, a result of showing constant image for a long time.
Is the effect permanent? How to prevent it?
Luckily, the ghosting display effect is not permanent. The crystals by design have their natural state to be in. It is possible to restore them to their natural position. You can do this by using a specific amount of current and voltage.
How to avoid the ghosting display effect:
Do not place high-contrast patterns side-by-side in a fixed image. This will increase the probability of LCD ghosting. It is due to the significant difference in the LCD charge in those areas. *See the image below
Use a background with bright colors. This will further reduce the possibility of ghosting. It will cause the reset of all crystals and erase any earlier persistence.
If possible, turn off the display, even for short amount of time (a few hours should work)
Apply motion on the screen. That is the most effective solution to avoid ghosting display. The motion does not need to be invasive. Let the elements, which are usually static, to move a bit. For example, instead of displaying a motionless ball, display a bouncing ball. The content stays the same, and the “bouncing” prevents the ghosting display on the LCD TFT.
What about the ghosting effect on IPS displays?
IPS ghosting also takes place. To reduce it you can take the same measures as in the above mentioned TN displays.