Liquid crystal multilayer study promises improvements in manufacturing techniques for LCD’s

Surface alignment of liquid crystal multilayers evaporated on a photoaligned polyimide film observed by surface profiler

In order to successfully fabricate a commercial Liquid Crystal Display, uniform orientation of the liquid crystal (LC) molecules is required. Traditionally this molecular alignment of liquid crystal is achieved by physically or chemically treating the surface. A simple method used to achieve preferred orientation is rubbing but this may produce dust, static charging and mechanical damage which deteriorates the production yield.

One of the more attractive alternatives to rubbing is the generation of a surface anisotropy of an alignment film by photochemical reaction called “photoinduced alignment”. In general, photoinduced alignment is achieved by exposing with both unpolarized and polarized ultraviolet (UV) light on a photoalignment polymer film.

In this study published under AZojomo*, by Thet Naing Oo, Tetsuya Iwata, Munehiro Kimura and Tadashi Akahane from Nagaoka University of Technology and Core System Co. Ltd, investigated of the surface alignment of liquid crystal multilayers evaporated on a photoaligned polyimide vertical alignment (PI–VA) film was carried out by means of a novel three–dimensional (3–D) surface profiler.

The photoinduced anisotropy of the partially UV–exposed PI–VA film can be visualized as a topological image of LC multilayers. It seems that the topology of LC multilayers indicates the orientational distribution of LC molecules on the treated film. Moreover, it was shown that the surface profiler can be used to produce non–contact images with high vertical resolution (~ 0.01 nm).

It is anticipated that this work will be a considerable aid to the manufacturers of liquid crystal displays (LCDs) across the range of LCD production from televisions to computer screens.