Yeon-Kyu Moon

Polarizer-free liquid crystal display with electrically switchable microlens array

We propose a polarizer-free liquid crystal display (LCD) with an electrically switchable microlens array. The incident lights are controlled to focused or defocused states by index matching of the lens polymer and LC layer. By adopting two light-blocking masks that have a circular stop pattern and the complementary open pattern, the LCD was able to realize the entire gray scale. Additionally, to achieve fast response time characteristics, we introduce polymerized RMs within the alignment layers.

Single pixel transmissive and reflective liquid crystal display using broadband cholesteric liquid crystal film

We propose a single mode transflective liquid crystal display (LCD) which is operated as the transmissive and reflective modes in a single pixel without dividing into sub-pixels. The single pixel transflective LCD was composed of the cross-polarized nematic LCD as a light modulator and the broadband cholesteric liquid crystal film (BCLCF) as a half mirror. The BCLCF, simply prepared by the exposure of ultraviolet light to the mixture of the nematic LC and the reactive mesogen with chirality, selectively reflects a certain circular polarization but transmits the orthogonal circular polarization in entire visible light. The electro-optical properties in both transmissive and reflective modes coincide with each other.

Inverse four-domain twisted nematic liquid crystal display fabricated by the enhancement of azimuthal anchoring energy

An inverse four-domain twisted nematic (IFDTN) liquid crystal (LC) display was fabricated by enhancing the azimuthal anchoring energy of the alignment layers. By stacking a vertical alignment layer onto a planar alignment layer, we increased the azimuthal anchoring energy by approximately 17-fold times compared to that with vertical alignment only. Due to the enhanced azimuthal anchoring energy, we were able to achieve a four-domain twisted nematic LC structure without dopant via the application of an external voltage. A simulation of the LC molecular orientation with respect to the azimuthal anchoring energy, the viewing angle characteristics, and the switching behavior of the IFDTN LC are presented.

Effects of surface modification with reactive mesogen on the anchoring strength of liquid crystals

We studied the effects of polymer chain ordering in the alignment layer and resulting molecular interactions on the surface anchoring energy by introducing a reactive mesogen (RM) coating to the alignment layer. Directionally polymerized RMs on the rubbed alignment layer decrease the steric repulsion and increase the electronic interaction with liquid crystal molecules, and, as a result, the surface anchoring energy is enhanced in both the out-of plane and in-plane directions. We also demonstrated that this enhanced surface anchoring energy can be used to improve the response time characteristics of liquid crystal displays.

Reflective three-dimensional displays using the cholesteric liquid crystal with an inner patterned retarder

We propose a reflective three-dimensional (3D) display using a cholesteric liquid crystal (ChLC) with an inner patterned retarder producing half-wave retardation. The inner patterned retarder, fabricated by selective ultra-violet exposure to the aligned reactive mesogen, divides the circularly polarized light reflected from the ChLC layer into two orthogonal circular polarizations. These reflected orthogonal polarizations construct stereoscopic 3D images without any optical components such as a polarizer and backlight unit.

Multicolor Cholesteric Liquid Crystal Display in a Single-Layered Configuration using a Multi-Pitch Stabilizations

We report a cholesteric liquid crystal (ChLC) display with multicolor in a single-layered configuration using a multi-pitch stabilization by reactive mesogen (RM). The cholesteric pitches were modulated by temperature and stabilized at room temperature by polymerization of the RMs through ultraviolet (UV) exposure. In a single-layered ChLC display without any additional layer such as a color filter, multicolor was obtained by a multi-pitch stabilization through spartially selective UV expose at several temperatures.

P-139: Control of Liquid Crystal Pre-tilt Angle Using Reactive Mesogen

We proposed a method to control pre-tilt angle of liquid crystals by coating vertical alignment reactive mesogen(RM) material on the planar alignment layer. The pre-tilt angle can be precisely and simply controlled in full range (0° ~ 90°). We also easily obtained a patterned alignment layer using this method.

P-156: Electrically Stabilized Four-Domain Twisted Nematic Structure with High Transmittance and Fast Response

We propose a novel method for a stable four-domain twisted nematic (4DTN) structure by injecting nematic liquid crystal in an isotropic phase under an applied electric field. In this method, no high pre-tilt angle is required to stabilize the 4DTN structure and thus the high transmittance and fast response are obtained.

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

In this paper, we propose a stable four-domain twisted nematic structure with wide viewing angle characteristics and a fast response time. A stable structure was realized by introducing a high pre-tilt angle approach incorporating stacked planar and vertical alignment layers. The response time and thermal stability of the proposed device were dramatically improved by the addition of UV-curable reactive mesogen (RM) mixed with a vertical alignment material. Polymerized RMs along the liquid crystal (LC) director increased the polar anchoring energy and reduced back-flow phenomena. A wide viewing angle and fast response time characteristics were achieved over all gray levels.

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

We proposed a stable four domain TN structure with high pre-tilt angle. A stacked alignment layer produced high pre-tilt angle and stabilized the four TN domains at even zero or low voltage regime. In our structure, the excellent viewing characteristics were obtained.