Premium
P‐18: Damage to TFT Displays During Polariser Replacement ‐ Analysis of Damaged Displays, Failure Mechanism, and Proposed Safe Removal Method
Author(s) -
Hampel Reinhard G. O.,
VialDavid Gérard
Publication year - 2003
Publication title -
sid symposium digest of technical papers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.351
H-Index - 44
eISSN - 2168-0159
pISSN - 0097-966X
DOI - 10.1889/1.1832254
Subject(s) - polarizer , liquid crystal display , pixel , materials science , line (geometry) , optics , optoelectronics , physics , mathematics , birefringence , geometry
Our customers stated uneven greyscales ‘clouds’ in TFT displays after polariser replacement. We counted spacer densities on displays before and after polariser removal by different methods. We found that the average spacer count falls to about 40% of its initial value after unsafe polariser removal. From microscopic observation of spacer distribution in pixels, we could conclude that the spacers get ‘trapped’ by the metal lines connecting the pixels. Unsafe removal methods exert a pressure on the LCD close to the polariser peel line. This induces a pumping action resulting in strong LC flow. The spacers moving with the LC liquid get trapped by the metal lines on the TFT substrate, and the spacers ‘disappear’ from the pixels. Condition for a safe removal method is thus that no pressure must be applied to the displays close to the peel line, close being defined as a distance of less than about 20–30 mm.