Pixel Defect Policy - Philips 227E3QPHSU/27 Service Manual

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4.3 Pixel Defect Policy

Philips strives to deliver the highest quality products.
We use some of the industry's most advanced
manufacturing process and practice stringent quality
control. However, pixel or sub pixel defects on the TFT
LCD panels used in flat panel monitors are sometimes
unavoidable. No manufacturer can guarantee that
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
LCD 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 standard for certain
types or 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 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
signal black pixel. Other combinations of lit and dark
sub 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
each category.
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 three
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.