January 04, 2006
What is the ISO 13406-2 standard for LCD screen pixel faults?

I'm in the market for a new screen to hook up to my cute little sub-notebook laptop.

While browsing, I noticed that all the flat panel monitors for sale at komplett.co.uk are labelled

All LCD displays adhere to the ISO 13406-2 standard with regard to pixel faults.
This, of course, tickled my attention, as my assumption was that by default, if I buy a flat screen monitor, it's without pixel faults ('dead pixels' are dots of the screen that don't display correctly, e.g. a black/mis-coloured dot in a space that's supposed to be white. Very annoying if you end up with a screen that has one).

NEC Display Solutions Sweden tells us the following about ISO 13406-2:

Pixel faults are a weakness typical of LCDs and are subdivided into four classes, 3 types of pixel fault and 2 concentration criteria within the framework of the ISO 13406-2 test. For the different types of pixel fault, a distinction is made between illuminated pixels, dark pixels and sub-pixel failures (or flashing pixels). The concentration criteria distinguish between firstly the number of white or black pixels occurring in a particular area (cluster) and secondly the sub-pixel failures or flashing pixels occurring within a cluster. The four classes of ISO-13406-2 define the maximum number of failures allowed for each type of pixel fault and each of the concentration criteria. Class 2 is typical. Class 1 is intended only for demanding special applications and Class 3 is for inexpensive models. Class 4 represents the reject criteria in manufacture.
The really interesting answer, however, is provided by new-monitors.co.uk: exactly how many pixels must be bad in a new monitor before the manufacturer is likely to give you a new one on the guarantee?
To regulate the acceptability of defects and to protect the end user, ISO have created a standard for manufacturers to follow. ISO 13406-2 recommends how many defaults are acceptable in a display before it should be replaced, within the terms & conditions of warranty.

All reputable manufacturers conform to and support the ISO 13406-2 standard.

The table below shows the allowable number of malfunctioning pixels that are acceptable, depending on the native resolution of the LCD and allowing for 2 malfunctioning pixels per million pixels.

Native resolutionNo. of pixelsNo. of million pixelsAcceptable defects
1024 x 768786,4320.82
1280 x 10241,310,7201.33
1600 x 12001,920,2001.94
2048 x 15363,145,7283.16

The table below shows the allowable number of malfunctioning sub-pixels that are acceptable, depending on the native resolution of the LCD and allowing for 5 malfunctioning sub-pixels per million pixels.
Native resolutionNo. of pixelsNo. of million pixelsAcceptable defects
1024 x768786,432  0.84
1280 x 10241,310,7201.37
1600 x 12001,920,2001.910
2048 x 15363,145,7283.116

The table below shows the allowable number of malfunctioning sub-pixels that are acceptable within a 5 x 5 block of pixels, depending on the native resolution and allowing for 2 malfunctioning sub-pixels within a 5 x 5 block, per million pixels.
Native resolutionNo. of pixelsNo. of million pixelsAcceptable defects
1024 x 768786,4320.82
1280 x 10241,310,7201.33
1600 x 12001,920,2001.94
2048 x 15363,145,7283.16

The above is relevant to Class II LCD panels.

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Comments

ya boy! I bought an iMac G5 with insight, and it had a dead pixel. So I went back to the retailer and insist they replace... -_-" In the end, they did replace and handed me a stack of papers on dead pixel and that less than 4 is acceptable...

Posted by: shing on January 5, 2006 03:22 AM

hello, I came across your blog by searching on norway... which i may be visiting... saw this entry, can't help but give my 2 cents worths' comments.

Posted by: shing on January 5, 2006 04:02 AM
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