Optical Investigation of Disclination Lines in Multidomain Twisted Nematic Liquid Crystal Display Created by Microrubbing

ABSTRACT

A microrubbing (μ-rubbing) process was utilized to create a four-domain twisted nematic cell with improved viewing angle characteristics in comparison to a single domain twisted nematic display. A metallic sphere of 1 mm in diameter was used to μ-rub homeotropic polyimide, resulting in planar alignment with a 10° pretilt. With our set of initial conditions, a 10° pretilt cannot stabilize the four-domain structure in zero field; however, the four-domain structure is stable for voltages above 1 V. Here we optically study the formation of disclination lines and the stability of the four-domain configuration with respect to the applied voltage. The director orientation of the four-domain cell is simulated using the 2dimMOS simulation software and the optical transmission using extended Jones matrix method. Iso-contrast plots of the four-domain structure are compared with the single domain structure.

Keywords:

• disclination
• four-domain
• liquid crystal display
• pretilt

Acknowledgments

Funding of this project was provided by Netherlands University Federation for International Collaboration (Nuffic). The author likes to thank Dr. Sunil K. Narayanankutty, Cochin University of Science and Technology, India, Chris van Heesch, Peter Minten (GTD) at Eindhoven University of Technology for their support.