Understanding pixel defects in TFT-LCD flat panel monitors

Polarizer scratch: Physical damage to the polarizer that does not damage the glass. When the unit
lights, lines appear bright (white) with dark patterns and do not vary in size. This defect may not
completely block the light emitted by any pixels.
Rubbing lines/defects: Horizontal or diagonal lines that appear gray when the display is dark and
may have resulted from a problem in the "rubbing process," which is part of the preparation of glass
panels used in the LCD.
Defect illustrations
Figure 9. "Stuck off" and "stuck on" sub-pixel defects and a contamination defect.
In the top image above, a dark spot on a white background results from a green sub-pixel which is
stuck in the "off" or dark state. Bright spots on a black background, as shown in the middle image,
are often caused by sub-pixels (in this case, a red sub-pixel) stuck in the "on" state. Finally, debris
trapped within the LCD structure can also result in dark spots, but under magnification these can be
distinguished from a "stuck off" subpixel, as the shape of the contaminating particle will often be
visible.