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News and Display Technology Technical Support by laptop-lcd-screen.co.uk

Laptop & Tablet Screens: Dead Pixels and Your Warranty or Guarantee

Information for re-sellers who buy wholesale laptop & tablet screens

Contrary to popular belief, replacement LCD screens for laptops, tablet devices and smartphones are not quality graded with letters. You may have seen sellers online offering Grade A+ or even A+++; however, no such grading exists. Instead, LCD screens are graded using numbers, (by manufacturers who adhere to ISO 9241.)

The ISO standard 

The details 

ISO 9241 standardizes grades, (explained below,) for the production of replacement screens. Though not a legal requirement, a good number of screen makers adhere to the ISO standard.  Laptop manufacturers use the ISO standard in loose ways, some adhering to it, a few bettering it but most, (like DELL and HP,) not sticking to it. 

Class 0 panels are rare, defect-free screens that are often used within major government institutions and within the military.  

Class 1 panels are carried by the majority of major suppliers. Class 1 displays permit any, or all, of the following: 

1 full bright (“stuck on white”) pixel

1 full dark (“stuck off”) pixel

2 single or double bright or dark sub-pixels

3 to 5 “stuck on” or “stuck off” sub-pixels (depending on the number of each)

Class 2 panels (as used by Acer) - permit any or all of the following:

2 full bright pixels

2 full dark pixels

5-10 single or double bright or dark sub-pixels (again, depending on the number of each; no more than 5 bright (“stuck on”) subpixels are permitted).

Class 3 panels (found on some eBay shops) - permit any or all of the following:

5 full bright pixels

15 full dark pixels

50 single or double sub-pixels stuck on or off

Now, there is a reason for the numbered classification of screens and it has nothing to do with the way the screen has been made or the materials used. Screens are manufactured with pixels, which are minute dots that make up the image on your display. 

A modern 1080p (FULL HD) screen will have over 1.2 million pixels. Imagine the pixels are tiny lights that can be on or off.

Because of the technology used, (i.e. millions of tiny lights,) it’s impossible to test every pixel before it’s fitted to the screen. In addition to this, even if you test the LCD, small particles of dirt (and/or imperfections in the glass,) can cause a pixel fault later on down the line.

For this reason laptop screens are graded by the manufacturer of the LCD part, AFTER they have been manufactured, (it being impossible to know, at the time of manufacture, how many screens could have slight imperfections.)

In point of fact, even Class 0 screens can develop dead pixels after they have been tested..

In most cases Class 0 screens are reserved for military use.

Laptop makers and replacement LCD parts organisations like us buy class 1 usually. Class one screens are on the most part perfect to the human eye however a percentage of them could develop a pixel fault or already have a pixel fault. Cheaper sellers will be buying class 2 or sometimes 3 panels (if the seller is very cheap). These are usually sub standard quality. Bright patches, pressure marks as well as other imperfections such as backlight bleed can occur on these types of screen.

To illustrate this fact, that all sellers  DELL, in particular, will not accept returns for screens that have less than 6 dead pixels. So in actual fact, DELL are saying here that they can't guarantee that there will be no pixel defects on their screens and that is because their supplier cannot offer them that guarantee either.

Class 1 and 2 screes will be sold by the LCD makers on the basis that a certain percentage may have a (or develop a) pixel defect. However, most of the time, you can’t actually see it because you’re talking about one dot amongst more than a million other dots (usually when you can see a dead pixel you’re actually seeing more than one pixel fault in a cluster as the individual dots that make up the picture are usually indistinguishable by the human eye.)

So, it is actually impossible for anybody to guarantee that a screen will have no dead pixels: even if you inspect the panel yourself, a pixel fault can develop by the time the screen arrives with the customer.

As manufacturers sell screens like this not only to the laptop makers but also to other suppliers like us, a certain percentage of which, (they explicitly state,) could have or develop dead pixels, these products are non-returnable as the anomaly is part of the manufacturing process, and therefore not covered by warranty.

Now, most of the time, this isn’t an issue as the quality of these products is generally very high. Clients that do receive a screen with a manufacturing anomaly or are unhappy with the product can simply return it, however most of our clients are over the moon with our products. If you buy wholesale / bulk screens, you are certainly going to come across this issue from time to time. A percentage of your bulk purchase (usually 5-15%) could potentially develop a pixel fault.

Technically these screens aren’t returnable for pixel faults as they were sold as pixel faulted screens. Though this is the case, here at laptop-lcd-screen.co.uk we are always prepared to accept returns for any unwanted products. Unfortunately, we cannot replace screens under warranty that have less than 4 dead pixels; as this is not considered a fault and is not covered by the manufacturer warranty.  You are still within your statutory rights to return the product to us if you are unhappy under the consumer protection laws.

Pixel policies

Laptop and tablet manufacturer policies:

Laptop Brand / OEM
Lit Pixels
Missing Pixels
Total Dead Pixels
Dell
7
7
7
IBM
5 to 11
5 to 16
9 to 16
HP/Compaq
7
7
9
LG / LG.Philips
6
6
10
Sharp
7
7
N/A
Acer
9 – 10
9 – 10
9 – 10
Apple
3
5
7
Samsung*
0
0
0
Fujitsu
3
3
3
Panasonic
3
3
3
Portable One
2
2
2
Sony
5
5
5
Toshiba
5
5
5
Alienware
2
2
2

 

* zero-dead pixel policy only valid in South Korea

Our pixel policy

We simplify the varying standards above and say, simply, that we will replace any screen with 3 or more visible pixel defects.

What's zero dead pixels?

Zero dead pixel screens do not exist. Even on Apple computers.

If we had a choice in the matter, we would always buy zero dead pixel screens, but, unfortunately, zero dead pixel screens just don't exist. We buy the best grade on offer and it's usually Grade 1. If there is no decent grade on offer we'll buy what is available and advise on our site: it's better to stock a panel with a lower grade than have it out of stock if the panel has become hard to find -  as far as we're concerned. No supplier promises zero dead pixels and, therefore, if you are a reseller you should be promising or expecting that. It’s just not possible.

When buying (and selling) replacement screens in bulk, re-sellers should remember that the promise of screens with zero dead pixels is (and always will be) empty. 

Further reading

Uncovered: Dead pixel policies for major manufacturers of laptop and tablet devices.

See also, how LCD screens work 

Legal Information: Our dead pixel policy and the terms of sale terms and conditions.

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