[Force Flow]

Here; this may help: http://www.infinitytech.com/website2...ive-pixels.pdf

Active matrix TFT LCD panels achieve their beautiful images, in part, because of the individual transistor placed at each pixel which controls the backlight shining through a given pixel (see Figure 1). Occasionally, these individual transistors will short, or otherwise malfunction, resulting in a defective pixel. There are two phenomenon which define a defective LCD pixel: A "lit" pixel, which appears as one or several randomly-placed red, blue and/or green pixel elements on an all-black background; or a "missing" or "dead" pixel, which appears as a black dot on all-white backgrounds. (By comparison, CRT defective pixels exhibit themselves as black holes in an all white raster. This is due missing phosphor material or an obstruction in the shadow mask.) The "lit" pixel phenomenon, more common than "missing / dead" pixels, results when a transistor occasionally shorts on and results in a permanently "turned-on" (red, green or blue) pixel. There are some possible corrective measures, such as "killing" a transistor using a laser, however, this just creates black dots which would appear on a white background. Fixing the transistor itself is not possible after assembly. Additionally, it is not possible to turn a "lit" pixel off, except for the aforementioned laser method, which essentially just makes the transistor in-operational, thus resulting in a black dot. Turned on or "lit" pixels are a fairly common occurrence in LCD manufacturing. Like their CRT counterparts, LCD manufacturers have set limits as to how many defective pixels are acceptable for a given LCD panel, based on user feedback and manufacturing cost data. The goal in setting these limits is to maintain reasonable product pricing while minimizing distraction from defective pixels for maximum user comfort. Considering the number of pixels contained in a LCD panel, this defective rate is quite minute. For example, a panel with a native resolution of 1024x768 pixels contains a total of 2,359,296 red, green and blue pixels per panel (1024 x 768x3 = 2,359,296). Therefore, a panel with 20 lit pixels would have a pixel defect rate of: (20/2,359,296)*100 = 0.0008%.