dead pixels question

guyster1973uk

hi folks i just had to get my laptop replaced by pc world yesterday because i found a few dead pixels and thankfully the replacement laptop is free of any dead pixels on the screen. i was wondering can dead pixels develop over time? just thought id ask as im unsure

thanks
guy

Hammyman

Its a possibility but rare. I'm surprised they exchanged it. There are different ISO standards for LCD panels and it is possible to have several dead or stuck pixels on a monitor/laptop display and it still be fit for purpose as it falls into the tolerance for that panel. The panels at the highest standard, which guarantees no dead or stuck pixels, are seriously expensive.

John_Gray

Here we are! Viewsonic VP2365wb 23" monitor, IPS screen, £193, zero pixel guarantee...

Esqui

The "standards" are quite low though; I think it's something like 6 or 7 dead pixels on a 1080p monitor is within standard. Not so great when they're clustered together in the centre of the screen though.

JasX

Hammyman wrote: »

Its a possibility but rare. I'm surprised they exchanged it. There are different ISO standards for LCD panels and it is possible to have several dead or stuck pixels on a monitor/laptop display and it still be fit for purpose as it falls into the tolerance for that panel. The panels at the highest standard, which guarantees no dead or stuck pixels, are seriously expensive.

DSR regs are great for avoiding dead pixels

hubert_cumberdale

i have about 3 on my laptop

i thought i had two on my LCD tele but its actually a pair of thunder bugs underthe screen somehow think they died now as they have been in the same place for ages

fwor

Esqui wrote: »

The "standards" are quite low though

The "standards" are also not relevant to consumers.

If you as a consumer were not told that the screen has defects at the time of purchase, you can reject it as faulty, irrespective of what the "standards" say.

Hammyman

Err, no you cant if it meets the ISO 13406-2 specification. As long as the number and pattern of dead pixels meet the standard of the screen, it isn't deemed defective.

Many people have thought the same as you and found out to their expense this is not the case.

Basically, this is the jist of 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 following page has a table showing the difference between the different classes:

http://www.asapcomputers.co.uk/articles/featured_lcd_quality_control.htm

guyster1973uk

well the laptop is less than a month old and lets just say they were not happy about exchanging it over deal pixels on the screen. which i basically said " its a defect and if it was ur laptop ud be annoyed as well and because i know their there im always gonna see them"

fwor

Hammyman wrote: »

Err, no you cant if it meets the ISO 13406-2 specification. As long as the number and pattern of dead pixels meet the standard of the screen, it isn't deemed defective.

Yes, but you make the very common mistake that this standard has any bearing on a consumer. It doesn't - it's a non-mandatory guide for manufacturers to assess the quality of their products. It still doesn't ~require~ that a consumer accept a product that has any defects, despite what some retailers would have you believe.

If you read the standard itself, you find that it is not relevant to consumers at all.

I agree with the OP - just call it a defect and that's all you need to say.

CoolHotCold

"Yawn"

Any Dixons Retail group have issued a internal policy regarding dead pixels. They can explain to customers due to the nature of screens and the complexity of manufacturing screens there are a certain amount of "Stuck" or "Dead" pixels before a unit is deemed faulty, however because we like to provide the best service and ensure all our customers are happy when they leave we will exchange and laptop/tv/monitor/camera etc etc which display any dead or stuck pixels.