Yong-Woon Lim

Mechanical stability of a flexible ferroelectric liquid crystal display with a periodic array of columnar spacers

We report on a high-speed flexible display based on a deformed helix ferroelectric liquid crystal (DHFLC) in a vertically aligned configuration. The mechanical stability of the flexible DHFLC display was achieved using a periodic array of columnar spacers formed directly on the top side of in-plane electrodes by the photolithography technique. Several unique features of display performances such as flexibility, uniform alignment, fast response, and gray scale capability were obtained. The switching time was found to be a few hundred microseconds.

Brightness-Enhanced Transflective Liquid Crystal Display Having Single-Cell Gap in Vertically Aligned Configuration

A brightness-enhanced transflective liquid crystal display having a single-cell gap was demonstrated in a vertically aligned (VA) configuration with a patterned retardation layer. The photopatterned retarder was made of a UV-polymerizable liquid crystal (LC) through a single patterning process. The homeotropic LC alignment in the transmissive region and the planar LC alignment in the reflective region were directly produced on the patterned retarder. High reflectance and fast response characteristics were achieved in a single VA transflective LCD with a patterned retardation layer.

A highly efficient organic light‐emitting diode with an imprinted in‐cell polarizer for backlight applications

Abstract A highly efficient organic light‐emitting diode (OLED) with an in‐cell polarizer made of an imprinted liquid crystalline polymer (LCP) layer doped with dichroic dye molecules is presented. The in‐cell polarizer was found to be capable of effectively polarizing the emission light of the OLED and of significantly improving the luminance through the periodic microstructures fabricated using an imprinting method. This type of OLED with an imprinted in‐cell polarizer is useful for efficient light source applications in liquid crystal displays (LCDs).

Tunable binary retarder using self-aligned liquid crystal on anisotropic polymer film by photo-assisted imprinting

We demonstrate an electrically tunable binary retarder (ETBR) with a self-aligned liquid crystal (LC) on an anisotropic polymer film produced by photo-assisted imprinting. The ETBR has two parts: a tunable optical layer of an LC and a static optical layer of an imprinted anisotropic polymer film possessing two different in-plane optic axes. The anisotropic polymer film was produced using reactive mesogens spontaneously aligned along the topographic microgrooves by imprinting under the exposure of ultraviolet light. An electrically tunable hybrid wave plate, whose phase retardation varies from a quarter to a half-wave, is constructed using the self-aligned LC layer on the imprinted polymer film that behaves as a quarter wave plate with two alternating optic axes. This approach can be used to design a new class of tunable optical devices with multiple in-plane optic axes.

P-158: Single Driving Transflective Liquid Crystal Display in a Single Mode Configuration with an Inner-Patterned Retarder

We have developed a single driving transflective liquid crystal display having an inner-patterned retarder in a single LC mode configuration. The inner-patterned retarder was fabricated on a patterned photoalignment layer using a self-masking technique. The measured electro-optic curves in the transmissive and the reflective parts were found to share common features that allow for a single driving scheme.

Polymeric Optical Films as Patterned Retarders and Alignment Layers for Transflective Liquid Crystal Displays

We developed a simple and versatile imprinting technique in combination with the exposure of ultraviolet light to fabricate several patterned optical wave plates using a polymerizable liquid crystalline (PLC) material. One of such patterned PLC films, produced by imprinting, can be used as both an in-cell retarder and an alignment layer for liquid crystal (LC) display applications. The chain ordering of the PLC molecules produced during imprinting results in anisotropic surface forces to align the LC molecules on the patterned PLC film without any surface treatment. A transflective LC display adopting an imprinted PLC film as an in-cell patterned retarder is demonstrated in a twisted nematic geometry.

Multi-functional nanopatterned optical films fabricated using capillary force lithography.

We demonstrate anisotropic optical films based on liquid crystalline polymer (LCP) using a capillary force lithography (CFL). The fabricated optical films can be used as both an optical component and a self-aligning capability of liquid crystal molecules introduced on the film. Additionally, HA or PA LC can be induced on same material by controlling the water repellency of LCP surface. Moreover, surface anchoring transitions could be controlled by variation of pattern sizes and surface treatment. In this point of view, one thin optical film can act both retarder and alignment layer and then shows good retardation, LC alignment, and transmittance at the same time.

P‐161: Brightness Improvement of Transflective LCD in a Unified Configuration

The brightness improvement of a transflective liquid crystal display in a unified configuration, having a single-cell gap and a vertically aligned (VA) liquid crystal (LC) mode, was demonstrated. The photo-patterned retarder was used to compensate the optical path difference between the transmissive and reflective regions. It was made of a UV-polymerizable liquid crystal (LC) through a single patterning process. High reflectance and fast response characteristics were achieved in our unified configuration.

68.2: A Transflective Liquid Crystal Display Having a Patterned Retardation Layer

We have developed a transflective liquid crystal display (LCD) having a single cell gap and a single LC mode by adopting a patterned retardation layer. In our transflective configuration, a single LC mode of the 60° twisted nematic LC was used for both transmissive and reflective applications. The patterned retardation layer was fabricated using a reactive mesogen by photo-patterning. The measured electro-optic characteristics of our transflective LC cell agree well with numerical simulations. Particularly, the transmittance was found to show similar behavior to the reflectance.

High-brightness and wide-view transflective liquid crystal display with two in-cell imprinted optical films in an inverse-twisted-nematic geometry

An inverse-twisted-nematic (ITN) transflective (TRF) liquid crystal (LC) display, where two imprinted optical films (IOFs) with surface microstructures are embedded was developed. One of the IOFs serves as an in-cell patterned retarder with multi-optic axes, and the other behaves as a viewing-angle enhancement film. In the presence of an applied voltage, the surface microstructures on the IOFs provide the spontaneous twist of the LC from a vertically aligned state to a 90° twisted-nematic (TN) state in the transmissive part, and to a 45° TN state in the reflective part. The developed ITN TRF LC display exhibits high transmission and reflectance, fast response, and wide-viewing characteristics, along with achromaticity.