Kwang-Soo Bae

Fast vertical alignment mode with continuous multi-domains for a liquid crystal display

We proposed a fast liquid crystal display (LCD) in a vertical alignment (VA) mode with continuous multi-domains for wide-viewing characteristics. The fast VA LCD was fabricated by the mixed vertical alignment layer with UV curable reactive mesogen (RM) polymer memorizing the switching directions of the LC molecules. The wide-viewing and fast response characteristics were obtained by axially symmetric switching directions and the memorization of them without any specific electrode patterns or surface structures.

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.

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.

Low Voltage and High Transmittance Polymer-Stabilized Blue-Phase Liquid Crystal Device by Combined In-Plane and Oblique Electric Field along the Horizontal Direction

We propose a polymer-stabilized blue-phase liquid crystal (PS-BPLC) device with high transmittance and low driving voltage by designing the electrode structure. The electrodes are comprised with two interdigitated bottom pixel electrodes with opposite polarities and a top common electrode with 0 V, which is placed in the middle of the two bottom electrodes. Since these electrode structures could generate a strong horizontal electric field and induce a high Kerr effect, we could realize a lower driving voltage (30 V) and higher transmittance characteristics (20%) than those of conventional PS-BPLC cells with an in-plane switching electrode structure.

P-131: Multi-Color Cholesteric Liquid Crystal Film by Fixing Helical Pitch with Reactive Mesogen

a multi-color cholesteric liquid crystal (CLC) film in a single-layered configuration with reactive mesogen (RM). The cholesteric pitches are controlled by temperature and memorized by photo-polymerization of the RM. Using the multi-pitch stabilization in a single layer, multicolor CLC display was obtained without any additional components.

P-122: Fabrication of Single Substrate Flexible LCD by Laminating Functional Polymer Cover Film

Abstract We proposed a lamination process of a polymer film with a photo-curable polymer for fabricating flexible liquid crystal (LC) displays on single substrate. In our structure, a cover film layer was tightly attached to the polymer wall structure of a bottom plastic substrate after lamination, and LCs were uniformly aligned by grooves formed on the laminated cover film. 1. Introduction Flexible displays have attracted much attention due to their good portability such as light weight, thin packing, and flexibility. Among currently available competing technologies, flexible liquid crystal displays (LCDs) are considered to be the most promising ones, in that they have well-established techniques guaranteeing superior visibility with low power consumption. The serious obstacles to successful commercialization of flexible LCDs have been highly nonuniform electro-optic (EO) properties under external mechanical distortions on the plastic substrates, which originated from LC distortion or cell gap variation [1, 3, 4, 5]. Our recent results showed that such problems could be effectively solved by using pixel-isolated liquid crystal (PILC) mode [4, 5], where the stabilization of LC modes and the cell gap uniformity were provided by polymer wall structures. However, previous works required cumbersome anisotropic phase separation from LC/polymer mixtures to make polymer wall structures or to attach the polymer wall structures on one plastic substrate to the other plastic substrate [4, 6, 7]. Therefore, several efforts have been devoted to the development of a simple fabrication process for stable flexible LCDs. Among them, fabrication methods of flexible LCDs on single plastic substrate are regarded to be very suitable ones in applying cost-effective roll-to-roll process [8-10]. In this work, we demonstrate that the PILC mode can be simply obtained by laminating functional cover film, where the top cover film is tightly attached to the polymer wall structures of the bottom plastic film via photo-polymerization and the LCs are well-aligned by the patterned groove structure on the cover films. The proposed lamination method can be achieved by laminating a photo-curable polymer film layer from surface modified elastomeric buffer layers. With the method, it is expected that stable flexible LCDs can be simply fabricated via a cost-effective roll-to-roll mass production.

Low voltage driven polymer-stabilized blue phase liquid crystal device with combined in-plane and fringe field

We present a low voltage driven polymer-stabilized blue phase liquid crystal (PS-BPLC) device by in-plane and fringe field inner cell. The combined electric field between the slit electrodes can penetrate deeply and induce higher birefringence in LC layer. Thus, high transmittance in our PS-BPLC device was obtained under lower driving voltage.

Single Pixel Transflective Liquid Crystal Display with Cholesteric Half Mirror

We propose a transflective liquid crystal display (LCD) operated in a whole pixel configuration consisting of the single-polarized LC cell and the broadband cholesteric LC (ChLC) half mirror. The broadband spectrum ChLC film is used for a polarization-sensitive mirror which reflects a given circular polarization but transmits its orthogonal polarization. Our transflective LCD can be demonstrated by just replacing the polarizer, placed toward a backlight unit in the conventional cross-polarized LC modes, with the ChLC half mirror.

Novel bonding technologies for flexible LCDs with mechanical stability under the pressing and bending deformation

Flexible display devices are widely and extensively studied for using the applications such as smart cards, PDA, head mounted displays and all kinds of mobile display because of their lighter weight, thinner packaging, and flexibility. However, it has some obstacles such as mechanical stability and tight adhesion of two plastic substrates. In this presentation, we will suggest a new bonding technologies with rigid spacers and bonding materials, which will serve mechanical stability and good adhesion strength. The micro-contact printing method is used to place bonding material on the rigid spacers that may be easily applicable to roll-to-roll fabrication processes. The performances of prototype samples fabricated will also be demonstrated by this technology.