How to Remove Dead Pixels From a TFT LCD
By Michael Martinez
In a TFT LCD (thin-film-transistor liquid-crystal display), each pixel has three sub-pixels: a red, green and blue. Each of these sub-pixels has its own transistor which allows the individual pixel to be turned on or off. These pixels and transistors are contained within a layer of insulating liquid between other transparent layers. Pixel size defects on the display can result from malfunctioning transistors or uneven distribution of this insulating liquid inside the display.
Dead or Stuck Pixel?
There are two main pixel level defects with LCDs -- dead pixels and stuck pixels. These are actually two separate issues, but the words are often used interchangeably. Dead pixels usually occur because the pixel transistor is defective and permanently stuck in an "off" state. The problematic pixel will usually be completely black. Unfortunately, a transistor issue is not fixable but still worth addressing because it's hard to identify and may actually be a fluid distribution issue. The manufacturer may have an acceptable limit for dead pixels, above which they will replace the monitor, bu these policies vary depending on manufacturer. Stuck pixels, on the other hand, can be due either to poor insulating liquid distribution, or transistors stuck in an "on" state on a particular color. Liquid distribution issues are often fixable, but transistor issues are not.
Stuck pixels due to uneven insulating fluid distribution can often be fixed by applying pressure to the area of the pixel. First turn off the monitor, then get a soft cloth and a pen or eraser with a dull and rounded end. Fold the cloth in two, put it on the monitor in the problem pixel area, then apply some slight pressure onto the cloth with the pen or eraser. Continue applying pressure while you turn the monitor on and see if the pixel color has reset. You could also simply use a pencil eraser and softly rub it directly onto the problem pixel. Try your finger or other methods to create a pressure point and attempt to massage the display.
An alternate method to fix a stuck pixel is by tapping. Keep the monitor on and use a screensaver or blanker to display a black screen or window. First find an item with a dull and rounded end, such as a pencil eraser end, pen end, or a sharpie with the cap on. Items used in the previous method will work just fine. The difference here is that you'll tap the pixel location on the screen directly with this item, and without using any cloth. Apply enough pressure so you see a small, white glow when you press on the screen. Do this a couple of times and then switch to a white screen or window and see if the pixel is unstuck.
If the previous methods did not work, you can try software designed to locate or fix dead or stuck pixels. DeadPixelTester runs various display tests to help you locate problem pixels but does not attempt flashing colors to try and fix them. UDPixel and PixelRepairer both help to find dead or stuck pixels and can attempt to fix these issues by rapidly flashing colors onto sections of the screen. These software suggestions are all Windows-based freeware. Note that the display of rapidly flashing screens may trigger seizures and epileptic attacks, so use these with care.
Michael Martinez has been working with computers since 1993. He fondly remembers the launch of Windows 95 and the original Pentium processors. Martinez has a Bachelor of Science in computer science.