Influence of Liquid Crystal Texture on Optical Parameters of Transmissive LCD Working Under High External Lighting

Abstract

The problem with using of transmissive liquid crystal displays under high external (sunlight) illumination conditions is widely well known for many years [1,2]. Especially, it can be seen in case of angle characteristics of luminance or contrast ratio. This problem can be partially solved, for example, by using antireflective layers, proper choosing of polarizers and texture of liquid crystal layer. In this work the influence of liquid crystal layer texture on angle characteristics of luminance and contrast ratio of the display operating under high external illumination is analyzed. To do it, transmissive liquid crystal displays with TN [3] and IPS [4] effects were chosen. The analysis was done using computer program [5,6] offering determination of optical parameters of a display for any observation angle and any optical parameters of the display elements, taking into account the interference phenomena occurring in a display, different direction of ordinary and extraordinary wavevectors, dispersion phenomena of refractive indices, absorption coefficients of the display layers, etc. These calculations were done for TN and IPS conditions, different polarizers, external light intensity and for negative display mode. The results have shown in detail the influence of chosen texture of LC layer on angle characteristics of optical parameters of a display working under high external illumination conditions.

Keywords:

• Contrast ratio
• high external lighting
• in-plane switching
• luminance
• twisted nematic

Acknowledgments

This work was supported by The Ministry of Science and Higher Education under grant N507 050 32/1472.