10
5.4. Pixel Defect Tolerances
In order to qualify for repair due to pixel defects during the warranty period, a PDP / TFT panel in
a Plasma / LCD display must have pixel or sub-pixel defects exceeding the tolerances listed in the
following table.
BRIGHT DOT EFFECT
ACCEPTABLE LEVEL
1 lit sub pixel
2
BLACK DOT EFFECT
ACCEPTABLE LEVEL
1 dark sub pixel
10
TOTAL DOT DEFECTS
12
5.5. Mura
Dark spots or patches may occasionally appear on some LCD panels. This is known within the industry
as Mura, which is a Japanese term for “unevenness.” It is used to describe an irregular pattern or area in
which uneven screen uniformity appears under certain conditions. Mura is a result of the deterioration
of the liquid crystal alignment layer and is most commonly caused by long-term operation under high
ambient temperatures. It is an industry-wide phenomenon and Mura is not repairable or covered by our
warranty terms. Mura has been around since the introduction of LCD technology and with screens getting
bigger and in operation 24/7, many displays are running in low light conditions. This all adds to the
possibility of Mura affecting displays.
How to Spot Mura
There are many symptoms of Mura and also multiple causes. Several of these are listed below:
• Impurities or foreign particles in the crystal matrix
• Uneven distribution of LCD matrix during manufacturing
• Non-uniform luminance distribution of the backlight
• Panel assembly induced stress
• Flaws within the LCD cells
• Thermal induced stress - high temperature operation over long periods of time
How to Avoid Mura
Although we can not guarantee the complete eradication of Mura every time, the appearance of Mura can
be minimized by using these methods:
• Lower the backlight brightness
• Use a screen saver
• Reduce the ambient temperature around the unit
