Definition Of Pixel Defects - Philips TFT LCD Colour Monitor Service Manual

17 190B4 LCD
0. General
This section explains the different types of pixel defects and
defines acceptable defect levels of 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.
1. Definition of Pixels and Subpixels
A pixel, or picture element, is composed of three subpixels in
the primary colors of red, green and blue. Many pixels together
from an image. When all subpixels of a pixel are lit, the three
colored subpixels together appear as a single white pixel. When
all are dark, the three colored subpixels together appear as a
single black pixel. Other combinations of lit and dark subpixels
appear as single pixels of other colors.
Subpixel
Subpixel
Subpixel
R G B
2. Types of Pixel Defects
Pixel and subpixel defects appear on the screen in different
ways.
Bright dot defects
Bright dot defects appear as pixels or subpixels that are always
lit or "On". These are the types of bright dot defects:
One lit red, green or blue subpixel
Two adjacent lit subpixels:
- Red + Blue = Purple
- Red + Green = Yellow
- Green + Blue = Cyan (Light Blue)
Three adjacent lit subpixels
(One white pixel)
Black dot defects
Black dot defects appear as pixels or subpixels that are always
dark or "off". These are the types of black dot defects:
One dark subpixel
Two or three adjacent dark subpixels

Definition of Pixel Defects

R G B
Pixel
G
R
B
P
Y
C
w
3. Pixel Defect Tolerances
In order to qualify for repair or replacement due to pixel defects
during the warranty period, a TFT LCD panel in a Philips flat
panel monitor must have pixel or subpixel defects exceeding
the tolerances listed in the following tables.
BRIGHT DOT DEFECTS
1. lit subpixel
2. adjacent lit subpixels
3. adjacent lit subpixels
(one white pixel)
Distance between two bright o\dot
defects*
Bright dot defects within 20mm circle
Total bright dot defects of all types
BRIGHT DOT DEFECTS
1. dark subpixel
2. adjacent lit dark subpixels
3. adjacent lit dark subpixels
Distance between two black dot
defects*
Bright dot defects within 20mm circle
Total bright dot defects of all types
TOTAL DOT DEFECTS
Total bright or black dot defects of all
types
ACCEPTABLE LEVEL
4 or fewer
2 or fewer
0
15mm or more
3 or fewer
4 or fewer
ACCEPTABLE LEVEL
4 or fewer
2 or fewer
0
15mm or more
3 or fewer
4 or fewer
ACCEPTABLE LEVEL
5 or fewer