Analysis of optical bounce associated with two-step molecular reorientation in the fringe-field switching mode

Abstract

The dynamic electro-optic response of liquid crystals (LCs) having positive dielectric anisotropy has been investigated in the fringe-field switching device. Simulation and experimental results show a huge optical bounce near the centre of the pixel electrodes of the device during decaying time of the LC director from an operating voltage. The causality of the said behaviour has been detected as two-step molecular relaxation, first tilt down and then rotating of the LC, which is associated with splay/bend and then twist relaxation, respectively. Reduction of dielectric anisotropy of the used LC material in the device has been suggested as a remedy of reducing optical bounce. The reduction of rotational viscosity also produces optical bounce of lesser duration; however, the intensity of the bounce remains invariant.

Keywords:

• fringe-field switching
• liquid crystal display
• optical bounce
• response time

Acknowledgements

This work was supported by the World Class University program (R31-20029) funded by the Ministry of Education, Science and Technology and also partly by Samsung Mobile Display Co.