Suppliers grade their particular stock, and while gradation scales can vary from supplier to supplier, typical A+ LCD screen will fall under the same defect policy as any major laptop screen manufacturer’s warranty policy – anything over 2-3 dead/suck is considered a defect.
We only purchase A+ parts.
And we even go further beyond – we will exchange any screen not up to expectations of the customer at no extra cost!
Pixels are in a way like light bulbs, they light-up different colors, and because there are lots of individual pixels on the screen we can see an image being formed by bright, dark and colored dots. If the light bulb won’t turn on – its a dead pixel, it it won’t turn off or won’t change color – its a stuck pixel. Having dead pixels on one screen and not having dead pixel on another does not mean that the screen is worse quality and the other one is better. Dead/stuck pixels are a fact-of-life defect for LCD screens, both low and high optical quality screens can have dead pixels. Factories try to balance their yield numbers to a number of acceptable defects. Therefore most laptop makers allow up to a certain amount of dead/stuck pixels on their brand new laptops to be excepted from being considered a defect.
To put dead pixel defects in perspective:
A FHD 1080p screen will have a total of 1920 x 1080 = 2,073,600 Pixels; and each of the pixels usually consists of 3 sub-pixels; for a total of 6,220,800 “light bulbs”. If any of them does not light up or turn off at the appropriate time – thats a dead/stuck pixel. Thats an astronomical ratio of working “light bulbs” to non-working.