Light Leakage Analysis of In-Plane-Switching Liquid Crystal Displays

Abstract

Light leakage in in-plane-switching liquid crystal displays (IPS LCDs) has been examined by image analysis and photon correlation measurement under a microscope. Static light leakage could be decomposed into a temperature-insensitive uniform part and a temperature-sensitive localized part. Nematic fluctuation effects in IPS LCDs are quantitatively clarified as follows. High-speed camera observation shows that dynamic fluctuation movements in a nematic layer modulate pixel images with static light leakage. The fluctuation level in the camera image is about 20% of the mean. However, spatial averaging over LCD pixel size suppresses fluctuation level into 3 -5%. This result coincides with the photon correlation measurement results.

P‐153: High Contrast Ratio LCD with an In‐cell Polarizer

“…The origins of depolarization are rather complicated; they may come from the diffraction effect of patterned thin-film transistors (TFTs) and electrode, light scattering from LC layer and color filter (CF) array, misalignment of crossed polarizers, and rubbing scratches, etc. [4][5][6][7][8] Fig. 2 schematically depicts some of these factors.…”

“…To improve CR, increasing the polarizer thickness is a straightforward approach. However, more evidences reveal that polarizer is no longer the limiting factor [4][5][6][7]. In fact, it is fairly easy to get CR > 100,000:1 with two high-quality crossed polarizers, but the final CR of an LCD is still limited to 5,000:1, which is mainly governed by the depolarization effect inside the LCD panel.…”

Depolarization effect in liquid crystal displays

“…To improve CR, increasing the polarizer thickness is a straightforward approach. However, more evidences reveal that polarizer is no longer the limiting factor [8][9][10][11][12]. In fact, it is fairly easy to get CR>100,000:1 with two high-quality crossed polarizers, but the final CR of an LCD is still limited to 5,000:1, which is mainly governed by the depolarization effect inside the LCD panel.…”

Transmittance Fluctuation from Nearly Extinct Nematic Cells

“…High-speed camera observation can reveal fluctuating dynamic texture images. 12) Using photon correlation setups, this fluctuating light leakage can be extracted from the IPS LCDs between ready-made crossed Nicols.…”