• Proceedings of the Optical Society of Korea Conference
• /
• 2009.02a
• /
• pp.349-350
• /
• 2009

• Korean Journal of Optics and Photonics
• /
• v.22 no.1
• /
• pp.23-29
• /
• 2011

Bistable chiral splay nematic liquid crystal display (BCSN LCD) is a memory type liquid crystal display using splay and $-\pi$ twist states as two stable states. When the cell thickness to pitch (d/p) ratio is 0.25, splay and $-\pi$ twist states have permanent memory time. However, when the transition from $-\pi$ twist state to splay state is caused by a fringe field, pixel regions show that the splay state is not perfect, but rather includes a contribution from the $-\pi$ twist state. In this paper, we propose a reflective BCSN LCD using $-\pi$ twist state in which the two stable states do not coexist. The fabricated reflective BCSN LC cell shows a high contrast ratio of over 30:1 and response times of 950 ms and 450 ms in vertical and fringe field switching, respectively. The proposed cell also shows wide viewing angle characteristics of $180^{\circ}$ in left- and right directions.

• Korean Journal of Optics and Photonics
• /
• v.26 no.2
• /
• pp.110-114
• /
• 2015

We propose a reflective cholesteric liquid crystal cell with reduced color shift, using dichroic dyes. Color-shifted light is absorbed by dye molecules in the proposed dye-doped cholesteric liquid crystal (DDCLC) cell. We have shown that the color shift can be reduced by increasing the concentration of dye molecules in the proposed DDCLC cell.

• Korean Journal of Optics and Photonics
• /
• v.19 no.3
• /
• pp.161-168
• /
• 2008

We propose a novel bistable nematic liquid crystal cell, which has a dual-frequency liquid crystal material and pixel-isolating polymer wall formed by an anisotropic phase separation of a mixture of liquid crystals and UV-curable pre-polymers. The proposed cell has two stable states of left- and right-handed ${\pi}$-twist. The switching between the two states is achieved by using a sequential waveform of low and high frequencies. A transmissive bistable liquid crystal display is designed, which achieves high contrast ratio by using the proposed cell and optical films.

• Applied Chemistry for Engineering
• /
• v.28 no.2
• /
• pp.230-236
• /
• 2017

We synthesized liquid crystalline polymers containing isosorbide group as a cholesteric derivative and methylene group for controlling the transition temperature to the liquid crystal phase. Effects of the concentration of the isosorbide group and the position of the methylene group on the properties of the liquid crystalline polymer were investigated. Among all the synthesized polymers, polymers (MnHI-x) with a methylene group in the main chain showed higher melting transition temperature and thermal stability than those (SnBI-x) with a methylene group in the side chain. All the synthesized polymers showed an enantiotropic liquid crystal phase. The polymers having 10 mol% isosorbide as a cholesteric liquid crystal phase derivative showed nematic phase, and those having 20 mol% or more isosorbide showed a cholesteric or chiral smectic phase. Thus, we can conclude that the isosorbide group plays a role as a cholesteric liquid crystal phase derivative.