Pixel Defect Policy - Philips 231B4LPYCB/75 Service Manual

4.3 Pixel Defect Policy

Philips strives to deliver the highest quality products.
We use some of the industry's most advanced
manufacturing processes
quality control. However, pixel or sub pixel defects on
the TFT Monitor panels used in flat panel monitors are
sometimes unavoidable.
guarantee that all panels will be free from pixel
defects, but Philips guarantees that any monitor with
an unacceptable number of defects will be repaired or
replaced under warranty. This notice explains the
different types of pixel defects and defines acceptable
defect levels for each type. In order to qualify for
repair or replacement under warranty, the number of
pixel defects on a TFT Monitor panel must exceed
these acceptable levels. For example, no more than
0.0004% of the sub pixels on a 21.5" XGA monitor
may be defective. Furthermore, Philips sets even
higher quality standards
combinations of pixel defects that are more noticeable
than others. This
policy is valid worldwide.
Pixels and Sub pixels
A pixel, or picture element, is composed of three sub
pixels in the primary colors of red, green and blue.
Many pixels together form an image. When all sub
pixels of a pixel are lit, the three colored sub pixels
together appear as a single white pixel. When all are
dark, the three colored sub pixels together appear as
a single black pixel. Other combinations of lit and dark
sub pixels appear as single pixels of other colors.
Types of Pixel Defects
Pixel and sub pixel defects appear on the screen in
different ways. There are two categories of pixel
defects and several types of sub pixel defects within
and practice stringent
No manufacturer can
for certain types or
each category.
Bright dot defects
Bright Dot Defects Bright dot defects appear as pixels
or sub pixels that are always lit or 'on'. That is, a bright
dot is a sub-pixel that stands out on the screen when
the monitor displays a dark pattern. There are the
types of bright dot defects:
One lit red, green or blue sub pixel
Two adjacent lit sub pixels:
- Red + Blue = Purple
- Red + Green = Yellow
- Green + Blue = Cyan (Light Blue)
Three adjacent lit sub pixels (one white pixel)
Note:
A red or blue bright dot must be more than 50 percent
brighter than neighboring dots while a green bright dot
is 30 percent brighter than neighboring dots.
Black Dot Defects
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