17.3: Electro‐Optical Properties of Polymer‐Stabilized OCB and Its Application to TFT‐LCD

Abstract

To eliminate an initial transition from splay to bend alignment, polymer-stabilized OCB was developed. The influences of the monomer concentration and the applied voltage during UV irradiation were studied, and stable bend alignment in the absence of electric field was obtained. The large retardation change and the fast response were achieved by using a mixture of multifunctional LC acrylate monomers, and a 9-inch full-color polymer-stabilized OCB TFT-LCD with initial bend alignment and the contrast ratio of 250:1 was successfully developed.SID 07 DIGEST • 995 ISSN/007-0966X/07/3802-0995-$1.00 © 2007 SID

Color Sequential Mobile LCDs

“…Unlike conventional homogeneous cells, in a pi-cell, the surface pre-tilt angles are in a parallel direction, as shown in Figure 5.4. There have been numerous successful efforts to develop methods that could speed up this initial 'splay to bend' transition and maintain the bend orientation even at a low voltage, such as using polymer network formation [20][21][22][23], high surface pre-tilt angle [24,25], or special driving schemes and fields with irregular electrode layouts [26,27]. As the voltage increases above the critical voltage, certain nuclei will be generated near the surface and propagate towards the bulk region to transform the alignment into a low bend state.…”

Trapping of defect point to improve response time via controlled azimuthal anchoring in a vertically aligned liquid crystal cell with polymer wall

“…A voltage of 3.6 V rms greater than the Freedericksz transition threshold (V th ) was then applied to the cell so that the reactive mesogen monomer and LC could be reoriented with a slight tilt angle from the surface in response to the electric field. In the presence of an electric field, the cell was exposed to UV light and thus the monomers were polymerized with a constant tilt angle at the surfaces through a photo-induced monomer diffusion process under optimal monomer weight per cent and UV curing conditions [10,[19][20][21][22]. Consequently, in the absence of an electric field, the LCs in the bulk relax to the original VA state while the surfaces have some defined pretilt angles.…”

Analysis of electro‐optical properties of polymer‐stabilized OCB and the application to TFT‐LCDs

“…In this paper, we report the development of a polymerstabilized OCB TFT-LCD with initial bend alignment adopting normally white mode. 15 To obtain stable bend alignment in the absence of an electric field, the influence of the polymer-stabilizing conditions was studied. In addition, to achieve high-quality performance such as high contrast ratio and fast response, a suitable choice of polymer materials is necessary as well as the optimization of the polymer stabilizing conditions.…”