Photoalignment – an alternative aligning technique for TN LCD

Abstract

The main aim of this work is to present our investigation in the field of photoalignment as an alternative technique for the rubbing method for composition of liquid crystal display. Liquid crystal displays are widely used in many industrial and commercial applications. The multimedia, CAD and graphics, medical-imaging systems require very high quality images. Such an image can be obtained on the condition of the good liquid crystal alignment. Rubbing is the method conventionally used for these purposes. Unfortunately, this technique has some disadvantages – especially visible in new generation displays. In this work we introduce the useful photoalignment techniques and in details the results of photocrosslinking and photodegradation in photosensitive polymer materials. We describe the procedure investigated in our laboratory for materials: HD-4100, HD-4110 (DuPont Microsystems) and B-12, as well as the characteristics obtained for the thin polyimide layers: optical homogeneity, thicknesses, surface tension and static electrooptical characteristics.