TFT Screens – All About Pixel Faults

Article publish date: October 8, 2019 - Article ID: 29865

One of the most common questions I get asked regarding TFT performance is related to pixel faults and ‘What makes a good or faulty panel?’ If you inspect any TFT very closely you will find faults, but this does not mean you have a faulty panel. You will need to consider, firstly, the type of fau​lt that might be exhibited:
Bright Dot fault Any Red, Green, or Blue pixel stuck in the “On” mode.
Dark Dot fault Any Red, Green, or Blue pixel stuck in the “Off” mode.
Dot Position fault Random / adjacent and the distance between the dots

tft 1

TFT 2

tft 3TFT 4

As a guideline for you, here is the Samsung position as stated on their Cosmetic Outgoing Inspection Specification (TFT LCD : A Grade) where the number = the total number of pixel faults on the panel:
​Number of Bright ​ ​ ​ ​Distance Bright to Bright Number of Dark Dots​ ​ ​ Distance Dark to Dark​ Maximum number of Dots​
​Dots Random
​<4 OK >4 Reject
​Random Green
​<2 OK >2 Reject
​2 Adjacent
​<3 OK >3 Reject
​3 Adjacent
​0 OK 1 Reject
​>15mm OK
​<15mm Reject
​Random
​<6 OK 6 Reject
​2 Adjacent
​<3 OK >3 Reject
​3 Adjacent
​<1 OK >1 Reject
​>5mm OK
​<5mm Reject
​<10 OK ​>10 Reject

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