Yeun-Tae Kim

Alignment layerless flexible liquid crystal display fabricated by an imprinting technique at ambient temperature

The authors report on an alignment layerless (AL) flexible liquid crystal (LC) display fabricated at ambient temperature through an imprinting process. One-dimensional microgrooves and two-dimensional arrays of microstructures embossed on plastic substrates provide the spontaneous alignment of the LC molecules and spacers for the uniform cell gap in a flexible LC display, respectively. It is found that the azimuthal anchoring energy, generated from the microgrooves, is on the order of 10−5J∕m2 which is strong enough to uniformly align the LC over large area. Our AL flexible LC display shows symmetric viewing characteristics and stable electro-optic properties under a bent environment.

Pixel-encapsulated flexible displays with a multifunctional elastomer substrate for self-aligning liquid crystals

We report on a pixel-encapsulated flexible liquid crystal display (LCD) based on an elastomer substrate of self-aligning LC molecules. The elastomer substrate, fabricated by a replica molding technique, has pixel-encapsulating walls that serve as spacers and allow for mechanical stability and reproducibility against bending deformations. Our pixel-encapsulated LCD provides great flexibility, durability, and excellent electro-optic performances in a highly bent environment.

Polarization Independent Static Microlens Array in the Homeotropic Liquid Crystal Configuration

ABSTRACT We propose a novel microlens array structure in a homeotropic liquid crystal (LC) configuration. The symmetry of molecular ordering in the homeotropic alignment on a circular surface relief structure provides the polarization independent focusing characteristics of the LC microlens. The surface relief structure of poly-dimethylsiloxane (PDMS) supports an initial convex lens driving scheme of the LC microlens as well as easy modification with great aging property.

Viewing Angle Switchable Liquid Crystal Display with Double Layers Separated by an Interlayer Support

We demonstrate a viewing angle switchable (VAS) liquid crystal display (LCD) with an interlayer support fabricated by imprinting lithography. The interlayer support is embedded in a single cell to separate two differently aligned LC layers, one of which is a primary layer for displaying images and the other is a complementary layer for switching viewing angles. Our VAS LC cell shows two viewing ranges that can be switched between ±40 and ±70°. Moreover, our method of using an interlayer support results in a reduction in the panel thickness and weight by 40% compared with the panel stacking method.

Novel wide viewing liquid crystal display with improved off-axis image quality in a twisted nematic configuration

We developed a novel twisted nematic (TN) liquid crystal display (LCD) having wide viewing angle characteristics through the reduction of the residual liquid crystal phase retardation at oblique angles using an embedded diffusing unit. Compared to a conventional TN panel, this embedded approach provides extended isocontrast contours by more than ±10 deg at a contrast ratio of 100:1 along the horizontal direction and a wide region free of grayscale inversion by a factor of 2 along the vertical direction. Moreover, the off-axis image distortions in our novel LCD are improved by 50% compared to those in a film-compensated TN LCD.

Stamping-assisted Fabrication Technique of the Bidirectional Alignment Layer for Wide-Viewing Twisted-Nematic Liquid Crystal Displays

Abstract A stamping‐assisted rubbing technique for generating bidirectional alignment in the fabrication of wide‐viewing twistednematic (TN) liquid crystal displays (LCDs) was developed. A patterned layer of a fluorinated acrylate polymer was transferred onto the first rubbed alignment layer prepared on a substrate by stamping. The fluorinated acrylate polymer provides a protective layer that covers the first alignment layer during the second rubbing process to facilitate the bidirectional alignment of the LC molecules. The LC cell in the twisted geometry with two bidirectional‐alignment layers showed stable electro‐optic properties and wide‐viewing characteristics. The stamping‐assisted rubbing technique serves as a mask‐free alignment method of producing multidomains for wide‐viewing LCDs.

Electrically and Optically Controllable Liquid Crystal Grating with a Patterned Surface-Command Layer

We propose a liquid crystal (LC) binary grating that can be controlled both electrically and optically in a simple scheme. The optical control scheme is obtained through the surface-induced reorientation of the LC molecules on a patterned surface-command layer by a single pump irradiation. The electrical control of the diffraction efficiency is achieved through the change in the phase retardation by the application of a bias voltage for given optically induced LC director distribution. In a coupled scheme of the optical and electrical control, the diffraction efficiency can be easily optimized.

P-144: Single Mode Transflective Liquid Crystal Display with Dual Cell Gap Using a Multipurpose Substrate

We describe a single mode transflective liquid crystal display (LCD) having a multipurpose substrate in a dual cell gap configuration. The multipurpose substrate fabricated by a replica molding technique provides the vertical alignment for the liquid crystal molecules without any surface treatment and bi-level microstructures as spacers to maintain different cell gaps in two sub-pixels. The elastomeric multipurpose substrate is thinner and lighert than a typical glass substrate. Our transflective LCD shows no electro-optical disparity between the transmissive part and the reflective part as well as enhanced portability due to reduction over 30 % in thickness and weight.

P‐76: Highly Efficient Backlight Unit with a Polarization‐Separating Anisotropic Layer

We have developed a highly efficient backlight unit (BLU) with a polarization-separating anisotropic layer on which asymmetric microstructures were embossed. Our BLU provides the polarized light along the direction normal to the anisotropic layer and has over 30% higher luminance than a BLU adopting a reflective polarizer.

Adhesive-Transfer Bonding Technique for Flexible Liquid Crystal Displays with High Mechanical Stability

We report on an adhesive-transfer bonding technique for improving mechanical stability of a flexible liquid crystal display (LCD) with an elastomer substrate. Permanent adhesion between an elastomer substrate and a plastic substrate is generated through thermal cross-linking of a curing agent prepared on the elastomer substrate by precise stamping. Our flexible LCD assembled using the adhesive-transfer bonding technique is found to show excellent mechanical stability in a highly bent environment.