<title>Photoalignment control of LC and its applications to LCD fabrication</title>

Abstract

ABSTARCTThe photopolymer materials of poly(vinyl cinnamate)(PVCi) and polyimides showing homeotropic liquid crystal (LC) alignment have been used to control LC alignment on these films using linearly-polarized (LP-) UV exposure, and the LC alignment mechanism including pretilt angle generation on the films has been discussed. In the case of PVCi, an important contribution of non-dimerized side chains of PVCi molecules to the LC alignment is pointed out. On the other hand, LC alignmemnt on homeotropically alignment polymer films exposed to LP-UV light is shown to be determined through the interaction of LC with alkyl branches attached to the polymer. It is also shown that the photo-alignment method using these photopolymer matrerials are very promising technique for the fabrication of some attractive LCD modes such as in-plane switching and vertically-aligned display modes, and an example of the application of the photo-alignment method to the fabrication of in-plane switching device is presented.

Effects of Temperature on the Alignment and Electrooptical Responses of a Nematic Nanoscale Liquid Crystalline Film

“…The liquid crystalline material 5CB exhibits a prototypical nematic phase that has been studied extensively in the past. , While representative of the materials finding use in the earliest versions of LCDs, the demands for high performance have led to the introduction of devices that exploit more complex mesogenic structures typically based on multicomponent LC mixtures. , Even so, 5CB remains a useful model system for studies of LC dynamics. Its responses to surface morphology and chemistry, for example, have been exhaustively studied and its alignment mechanisms on various surfaces are now reasonably well understood. − Among the various mechanisms used to align this phase, we examine one that was first discovered in the 1940s by Chatelain (and analyzed in the 1970s by Berreman 16,17 ).…”

Photo-Induced Vertical Alignment of Liquid Crystals via In Situ Polymerization Initiated by Polyimide Containing Benzophenone

“…In order to achieve perfect vertical alignment, many methods have been taken to control the pretilt angle, such as rubbing vertical alignment [ 4 , 5 , 6 , 7 , 8 , 9 ], polymer-sustained vertical alignment (PSVA) [ 10 , 11 , 12 ], and photo-induced vertical alignment [ 13 , 14 , 15 , 16 , 17 ]. Among these alignment methods mentioned above, the PSVA technology showing strength through its fast response, high transmittance, and simple manufacturing process [ 18 ] has been widely investigated.…”

VAN LCOS Microdisplays: A Decade of Technological Evolution

“…In the original report by Gibbons [24], polyimide films doped with photo-sensitive azo-dye compounds are used. Later on mainly poly-vinyl-cinnamate and its derivatives have been used [25]- [27], but also polyimides [28] and other reactive polymers [29]. Alignment of liquid crystal molecules is for most polymers triggered by a process of photodegradation.…”