NEC 500 Guide De Référence

 

displays have been certified according to manufacturing standards and do not reveal pixel faults to 
the untrained human eye.  Remember that each pixel, or dot, on a color LCD is actually made up of 
3 sub-pixels

one for red, one for green and one for blue. On an 18" VIS LCD display, the typical 

resolution is 1280 pixels by 1024 pixels (often referred to as 1280 x 1024 or SXGA), so there are 
1280 x 1024 x 3 sub-pixels, or 3.9 million sub-pixels

each of which measures less than 0.28 mm 

in height and 0.09 mm in width. For comparison purposes, the finest tip of a mechanical pencil 
designed for precision drafting work is often 0.3 mm, so a sub-pixel at 0.09 mm is less than 1/3 of 
this width and barely perceptible to the naked eye in most working environments.

 

 

 

I

0

II

1-5

III

6-50

IV

51-500

Table 1. Maximum number of faults per type per million pixels. 
 

Summary 

 
Until yields increase, material costs come down or new technology is developed to address the 
issue of defective pixels in LCDs, this phenomenon will occasionally present itself to some users 
under some circumstances. Most users, however, will never notice LCD pixel defects within the 
acceptable range. In addition, despite the occasional lit pixel to contend with, LCD technology 
continues to offer significant benefits over CRTs. These older-technology displays have other 
annoying artifacts, such as geometric distortion and misconvergence, which are nonexistent in 
LCDs. In addition, CRTs’ greater size, weight and power consumption make LCDs all the more 
attractive, even with the occasional defective pixel. Finally, some more good news for LCD users: 
transistors do not generally "go bad" over time, so if there are no noticeable dead or lit pixels upon 
initial purchase, then chances are none will become defective over time. 
 
For more information on dead pixels, refer to: 
 
• “Dealing with Dead Pixels in TFT Displays,” Charles W. Moore, Low End Mac. 

• “New EU Standard Targets Flat Panel Visual Displays: ISO 13406-2 Picks Up Where ISO 9241 
Leaves Off,“ TUV Rheinland World News, The International Journal of Safety and Standards, 
Trends & Information.