High pretilt four-domain twisted nematic liquid crystal display by microrubbing: Process, characterization, and optical simulation

Abstract

. (2005). High pretilt fourdomain twisted nematic liquid crystal display by microrubbing : process, characterization and optical simulation. Journal of Applied Physics, 97(5), 53101-1/8. [53101]. DOI: 10.1063/1.1854203 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. A microrubbing ͑-rubbing͒ technique was utilized to create four-domain alignment in a liquid crystal display sample. A small metallic sphere under sufficient load was used to directly rub a homeotropic polyimide alignment layer to create a large surface pretilt angle. We demonstrate a 47-m linewidth and a variable pretilt angle with respect to the substrate plane for different loads. The homeotropic polyimide surface was rubbed in such a way that neighboring alignment regions are rubbed in opposite directions. liquid crystal cells were constructed with two -rubbed substrates where the rubbing directions are orthogonal to each other. With this cell configuration we obtained four domains consisting of two left-handed and two right-handed twisted nematic subpixels. We report on the electro-optic performance properties, viewing angle characteristics, the relationship between pretilt angle versus load, and thermal aging study of the four-domain liquid crystal cell. The optical simulations of the liquid crystal director orientation, viewing angle characteristics, and the contrast ratio of the four domains are also presented. The experimental results are in agreement with the simulation results.

Liquid Crystal Aligning Ability of Photosensitive Polymer Material

“…The aligning materials, both the organic and inorganic ones, cover the substrates and ensure an orienting process in the LC material thanks to their anisotropic properties. Anisotropy in layers may be generated in such physicochemical processes as: laser writing [2], silica oxide deposition [3,4], microrubbing [5], plasma beam irradiation [6], ion-beam irradiation [7], photoalignment, PA, Langmuir-Blodgett layer deposition [8], usage of dendrimer-like structures with azo-moieties attached [9], or with an ordinarily used technique-rubbing. Each of the processes mentioned above has its advantages and disadvantages in preparation of liquid crystal devices, dependent on their further utilisation.…”

Four-domain twisted nematic structure with enhanced liquid crystal alignment stability and fast response time

“…Numerous techniques have been developed including multiple rubbing, multiple UV exposure, and multiple deposition of SiO 2 among other approaches. [4][5][6][7][8] Since most of these techniques require a chiral dopant to stabilize the 4-D TN structure, there can be only one twist sense in a pixel. Thus, while a 4-D TN structure can be achieved using the techniques described above, current fabrication methods are cumbersome and are not readily applicable for mass production.…”

P‐129: Stable Four‐domain Twisted Nematic Structure using Stacked Alignment Layer

“…The method to using negative birefringence films improves viewing angle characteristics but this method cannot compensate all gray levels. Multi-domain TN structures have been developed by many research groups with various methods [6][7][8][9][10][11] and the improvement in the viewing angle characteristic is clearly visible. Among them, the four-domain TN structure is the powerful method to improve viewing angle characteristics.…”

“…However, conventional four-domain TN structures have problems of unstability at zero or low voltage during switching. The fourdomain TN structure appears above certain voltage (stability voltage) [9][10][11]. Chen and co-workers [8] suggested the theoretical model to evaluate how the stability of four-domain TN display depends on geometry terms such as the tilt angle θ, sub-pixel dimension L, and the cell gap d. The suggested stability condition is as follows: θ 2 ≥ πd/L.…”