Jun H. Souk

21.2: Optimum Film Compensation Modes for TN and VA LCDS

The compensation principle to reduce the off-axis light leakage of crossed polarizers is investigated. After optimizing the retardation films, the simulation results show that the black state of viewing angle of compensated TN and VA modes can be made wider than the angle of view of crossed polarizers. The results are also confirmed by the test cells.

Fast In-Plane Switching of a Liquid Crystal Cell Triggered by a Vertical Electric Field

We propose a fast two-step switching method of a homogeneous-aligned liquid crystal (LC) cell, where a trigger pulse is applied to align LCs vertically for a moment before they are in-plane switched to show a bright state. Because LCs aligned vertically by a trigger pulse are in a transient state rather than the stable state, the turn-on becomes faster. The turn-off also becomes faster because the pulse forcibly aligns the LC vertically to show the dark state. Experimental results show that significant acceleration of the grey-to-grey response as well as on-off switching can be achieved by the proposed switching method.

Fast Switching of Vertical Alignment Liquid Crystal Cells with Liquid Crystalline Polymer Networks

This paper reports on the electro-optic characteristics of vertical alignment (VA) liquid crystal (LC) cells with liquid crystalline polymer networks. Optical bouncing, that occurs during the turn-on of VA cells, can be eliminated by introducing in-cell polymer networks. Furthermore, the turn-off also becomes much faster because of the anchoring effect caused by the anisotropy in the molecular shape of the liquid crystalline polymers. These response times have been found to vary for different LC/prepolymer mixtures. When the concentration of the liquid crystalline prepolymer in the initial LC/prepolymer mixture was 3, 5, or 10 wt %, the response times were measured to be 34, 56, and 87% faster than those of a VA cell with pure LC. These switching behaviors of VA cells with liquid crystalline polymer networks are demonstrated and compared with those using pure LC and with polymer networks made of isotropic prepolymers.

Motion artifact elimination technology for liquid‐crystal‐display monitors: Advanced dynamic capacitance compensation method

— A new technology, advanced dynamic capacitance compensation (A-DCC), for improved dynamic performance of LCD monitors, is presented. Conventional LCD monitors suffer from certain specific artifacts, such as wire-frame flicker and line dimming, which are not issues for the simpler motion images found in television content. A-DCC addresses these more-challenging monitor cases by means of an advanced architecture which analyzes multi-frame data and applies more comprehensive lookup-table corrections according to the specific frame sequence.

41.3: New LCD Modes for Wide‐Viewing‐Angle Applications

Two novel liquid crystal display modes are proposed for wide viewing angle applications. One is named as “electrically-induced optical compensation (EOC) mode”. It adopts the homeotropic alignment, positive dielectric liquid crystal as well as self domain divided method. The other is named as “Reverse Twisted Hybrid Aligned Nematic(RT HAN) mode” in which the IPS panel structure plus the hybrid LC mode is used. The display principle as well as the performance measured from real displays will be presented.

Simple multimode stereoscopic liquid crystal display

A novel multimode stereoscopic imaging system is developed. The system consists of a polarizer and a passive liquid crystal sheet which is patterned into periodic liquid crystal configuration regions. One is in the 90° twisted nematic (TN) state while the other is in a non-twisted state (liquid crystal aligned antiparallel). This 3D imaging system can be viewed in the autostereo mode without spectacles but has discrete viewing zones and in a binocular stereo mode which requires passive polarized glasses. This system is also convertible between 2D and 3D modes. Its principle is confirmed using the test cells. The viewing angle characteristics are also investigated.

Recent Picture Quality Enhancement Technology Based on Human Visual Perception in LCD TVs

Picture quality enhancement technologies applied by human vision system (HVS) were introduced. A smooth eye pursuit mechanism was applied to moving picture quality enhancement. The fast frame-rate and impulsive-like driving methods were reviewed. A new analysis method of a color reproduction capability of TVs was introduced and had its importance pointed out. Luminance-related issues in liquid crystal display (LCD) TVs were reviewed, such as eye fatigue by high luminance and maximum perceptible contrast ratio of the display.

48.1: A Novel Method for Image Contrast Enhancement in TFT-LCDs: Dynamic Gamma Control (DGC)

This paper describes a novel method for image contrast enhancement by controlling gamma curve in AMLCD. The key idea is to automatically manipulate gamma voltage in accordance with the image data distribution. This method is applied to 17″ SXGA LCD monitor module. The contrast ratio and the brightness are enhanced by about 3 times and 1.7 times, respectively, by using the proposed method.

P-38: Driving Scheme for Improving Color Performance of LCD's: Accurate Color Capture

This paper describes a novel driving scheme, ACC Accurate Color Capture, for improving color accuracy of LCDs. ACC changes RGB gamma curves separately to reduce the color shift with respect to the gray level. ACC dramatically reduced correlated color temperature shift from 3300K to 75K through 255-64 gray range with 2.4 gray gamma value. As experimental results, ACC is little affected by gamma value variation of 2.0–2.8.

Micro‐cavity design of bottom‐emitting AMOLED with white OLED and RGBW color filters for 100% color gamut

— Two optical structures used for a bottom-emitting white organic light-emitting diode (OLED) is reported. An RGBW color system was employed because of its high efficiency. For red, green, and blue (RGB) subpixels, the cavity resonance was enhanced by the use of a dielectric mirror, and for the white (W) subpixel, the mirror was removed. The optical length of the cavities was controlled by two different ways: by the thickness of the dielectric filter on top of the mirror or by the angle of oblique emission. With both methods, active-matrix OLEDs (AMOLEDs) that reproduced a color gamut exceeding 100% of the NTSC (National Television System Committee) standard were fabricated. More importantly, the transmission of a white OLED through R/G/B color filters was significantly higher (up to 50%) than that of a conventional structure not employing a mirror, while at the same time as the color gamut increased from ∼75 to ∼100% NTSC.