TFT monitors are precise units made up of a set number of pixels. Unfortunately this can be seen as a weakness. Pixels are made up the three sub-pixels being red, green and blue each consisting of their own transistors that controls whether or not it lights up. Due to the way in which panels are made, defects can unfortunately appear resulting in ‘dead pixels’ which cannot be repaired neither can it be predicted when the failure may occur.

The monitor can be working at 100% however can consist of pixels or sub-pixels which are either:
a) Permanently dark or light which is not always evident OR
b) A constant flash which is more noticeable.

Fortunately there is an ISO 13406-2 (Class II) standard which covers the maximum number pixels on any given panel.

The pixel faults are defined in the following way:

Type 1) constant bright pixel

Type 2) constant dark pixel

Type 3) defect pixel, either constantly bright (red, green, blue or constantly dark)

Type 4) fault cluster, the number of defective pixels in a 5 x 5 pixel square.

Panel type	Physical Resolution	Maximally permissible number of errors for the pixel error classII in accordance with ISO 13406-2
		Type 1	Type 2	Type 3	Cluster fault (all types)	Cluster fault Type1 & Type 2
15" XGA	1024 x 768	2	2	4	2	2
17"-19" SXGA	1280 x 1024	3	3	7	3	3
20.1" UXGA	1600 x 1200	4	4	10	4	4

Based on the standard ISO 13406-2 the customer can use the tables explained above as basis for the evaluation of the pixel error tolerance. Excess of one of the specified border criteria leads to the entry into force of the warranty claim.