Dark Dot Defects; Proximity Of Pixel Defects; Pixel Defect Tolerances; Mura - Philips BDL4830QL User Manual

BDL4830QL
8.4.

Dark Dot Defects

Black dot defects appear as pixels or sub-pixels that are always dark or "off ". These are the examples of black dot defects:
One dark dot
8.5.

Proximity of Pixel Defects

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‡ Allowed amount of adjacent dark dots = (adjacent dark dots =1 pair of dark dots)
‡ Minimum distance between dark dots
‡ Total no. of all defective dots
8.6.

Pixel Defect Tolerances

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pixel defects exceeding the tolerances listed in the following table.
BRIGHT DOT EFFECT
1 lit sub pixel
BLACK DOT EFFECT
1 dark sub pixel
TOTAL DOT DEFECTS OF ALL TYPES
NOTE: * 1 or 2 adjacent sub pixel defects = 1 dot defect
8.7.

MURA

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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
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is an industry- wide phenomenon and Mura is not repairable. It is also not 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, in general the appearance of Mura can be minimized by these methods:
‡ Lower the backlight brightness
‡ Use a screen saver
‡ Reduce the ambient temperature around the unit
Two adjacent dark dots = 1 pair of dark dots
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minimum distance between dark dots
ACCEPTABLE LEVEL
2
ACCEPTABLE LEVEL
10
12