Definition Of Pixel Defects - Philips 200VW8 Service Manual

10
200VW8 LCD
Adjust the contrast and brightness on
OSD Main Controls.
The screen is too bright or
(The backlight of the LCD monitor has a fixed
too dark
life span. When the screen becomes dark or
begins to flicker,please contact your dealer).
If an image remains on the screen for an extended
period of time, it may be imprinted in the screen
An after-image appears
and leave an after-image. This usually disappears
after a few hours.
This is characteristic of liquid crystal and is not
An after-image remains after caused by a malfunction or deterioration of the
the power has been turned off liquid crystal. The after-image will disappear after
a peroid of time.
Green, red, blue, dark, and The remaining dots are normal characteristic of
white dots remains the liquid crystal used in today's technology.
For further assistance, refer to the Consumer Information Centers list
and contact your local Philips distributor.

Definition of Pixel Defects

This section explains the different types of pixel defects and
defines acceptable defect levels of each type. In order to
quality for repair or replacement under warranty, the number
of pixel defects on a TFT LCD panel must exceed these
acceptable levels.
1. Definition of 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.
subpixel subpixel
R
R G B
2. 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.
Definition of Pixel Defects
subpixel
G B
Pixel
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)
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
Black dot defects appear as pixels or sub pixels that are
always dark or 'off'. That is, a dark dot is a sub-pixel that
stands out on the screen when the monitor displays a light
pattern. These are the types of black dot defects:
One dark sub pixel
Two or three adjacent
dark sub pixels
G
R
B
P
Y
C
W