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11.1. Pixel defect
In case of flat screens pixel defects occur related to technology and production. A 22“ display
with a resolution of 1920 x 1080 pixels e.g. consists of more than 2 million individual screen
cells controlled by tiny transistors. With such a tremendous number it is possible that in
spite of highest quality standards one or several individual cells are not perfectly functioning,
and are permanently switched on or off. Then, the outcome are continuously shining or
continuously black pixels on the screen.
In this respect, the ISO standard 13406-2 defines quality classes providing transparency
with respect to warranty claims of final customers, retailers and wholesalers against the
manufacturers. With the commitment to an ISO defect class, the monitor manufacturers
undertake to comply with the corresponding standard for serial production. In this, the pixel
defect classes are guided by the number of pixel defects and by the specific defect type, as
explained in the following table. The pixel defect number is defined each time per 1 million
pixels.
Distinguished are the following three defect types:
The ISO defect classes are defined as follows:
Number: defective pixels per 1.000.000 pixels
A continuously shining pixel (defect type 1) is more disturbing for thee user than a continuously
black pixel (defect class 2). The least evident is, if only one subpixel is defective, and shines
in one of the three colours red, green or blue, or is black (defect class 3).
Because of these differences also the respective accepted number of defects of the three
defect types is different, e.g. in class II. While defect class 1 and 2 are only allowed to appear
twice, five defective subpixels (defect type 3) are allowed.
All flat-screen monitors offered by Caratec GmbH correspond to class II, if not otherwise
specified.
Defect type 1
continuously shining pixel
Defect type 2
continuously black pixel
Defect type 3
defective subpixel or continuously shining (red, green blue) or continuously black
Defect class
Max. number type 1
Max. number type 2
Max. number type 3
I
0
0
0
II
2
2
5
III
5
15
50
IV
50
150
500
