高透过率共面转换液晶显示器

我们开发了一种在同一个基板上使用特殊电极设计的高透过率共面转换(HT-IPS)液晶显示器。这种特殊的电极构造在电极组之间产生实际的水平电场,在电极组区域内的边缘电场具有较高水平场成份。上半部分类似于IPS模式,而下半部分类似于边缘场转换(FFS)模式。HT-IPS模式显示出了很高的透过率[大于扭曲向列相(TN)模式的90%],同时,无论使用正性或负性各向异性的液晶材料,液晶盒都具有宽视角。此外,我们对比了相同条件下HT-IPS与IPS、FFS盒的光电特性。     

基于菱形电极结构的高对比度平面内扭转模式蓝相液晶显示器件设计

以往研究发现平面内扭转(In-Plane Switching,IPS)模式蓝相液晶显示器件的图像显示对比度明显低于理论预期。本文对导致这一问题的物理原理进行理论分析和实验验证,据此提出改进的菱形电极结构设计以解决这一问题。实验证明,调整走向后的IPS电极结构能使蓝相液晶显示器件的暗态漏光减小2/3,使其显示对比度提升至10 000∶1以上。基于这一实验发现,本文提出了全新的菱形电极结构设计,以求获得高对比度显示效果。除此以外,采用Techwiz仿真分析改进后的菱形IPS电极蓝相液晶显示器件的电光特性,发现其伽玛偏移和灰度反转可分别减小3/4和2/3,并且其驱动电压和透过率与传统IPS模式蓝相液晶显示器件相仿。可见,基于改进的菱形IPS电极结构的蓝相液晶显示器件相较传统蓝相液晶显示器件具备更好的显示性能和市场竞争力。     

快速响应的共面转换型液晶显示器

共面转换液晶显示器(IPS-LCD)由于其具有可视角度大、色彩真实、画质出色等优点,在平板显示器中得到了广泛应用,然而响应速度慢限制了其在高端显示器中的应用。本文中,首先通过采用正性液晶,对IPS类型中的边缘场转换型(FFS)和边缘场共面转换型(FIS)的液晶显示器,不同摩擦角度下的电光特性和响应时间进行了模拟计算。然后从预倾角度、电极尺寸以及弹性常数出发,对FIS液晶盒结构参数进行了优化,提出了一种快速响应的液晶显示器。我们通过计算机模拟发现,在FFS液晶盒中,摩擦角度对工作电压具有较大影响,小摩擦角度可实现高透过率、低工作电压;而在FIS液晶盒中,摩擦角度对响应时间具有较大影响,大于10°时与2°时相比,响应速度可提高82.7%以上。并且,不同摩擦角度下,弹性常数对FIS液晶显示器的响应速度影响不同,摩擦角度为2°时,响应速度与弹性常数K11、K22、K33都有关,而摩擦角度为12°时,响应速度只与K22有关,这个原因导致了12°与2°时相比,响应速度提高了84.2%。     

Influence of ion transport on liquid crystal switching

The coupled interaction between the reorientation of a liquid crystal and the migration of ionic impurities in the presence of an applied electric field is investigated for two device types commonly used in displays, the planar and the in-plane switching (IPS) cell. Simulated optical measurements and transient currents are compared to experimental results in order to discover means to alleviate the problems associated with ion migration. IPS cells have a lower electrode surface area than planar cells, and are therefore more sensitive to the movement of a given ion concentration. As a means to reduce this sensitivity, the effect of altering the electrode width and gap is studied.     

Recent Trends on Patterned Vertical Alignment (PVA) and Fringe-Field Switching (FFS) Liquid Crystal Displays for Liquid Crystal Television Applications

This paper reviews the recent trends on super-patterned vertical alignment (S-PVA) and fringe-field switching (FFS) technologies for liquid crystal display (LCD)-television (TV) applications. For PVA mode, Samsung originally announced S-PVA technology in 2004 to enhance off-axis viewing quality of conventional PVA mode. S-PVA is a new technology which enables screen quality advantages over super-in plane switching (S-IPS) and multi-domain VA (MVA), including high transmittance, >2300:1 contrast ratio, and wide viewing angle with no off-axis image inversion. This paper explores and updates Samsung's latest developments toward its goal of ultimate LCD-TV performance. For FFS mode, the technology appeared in 1998 by HYDIS and now it has been commercialized in all kinds of display applications, implying its technical importance. This paper reviews recent developments and performance of LCD-TV using the FFS mode based on published papers and our knowledge.     

一种用于增加制程范围的新型FFS液晶显示器件结构

FFS(fringing field switching)技术作为三大主流广视角液晶显示技术之一,与IPS/VA相比有高开口率的优势。然而由于其存储电容易受制程偏移的影响而较容易产生显示不均,因此在制造过程中对设备精度要求十分严格。本文介绍一种新的FFS器件结构,能很大程度上降低由于制程偏移造成的显示不均。     

一种新型单偏振片反射式液晶显示器的设计

提出一种新型单偏振片反射式液晶显示器的设计方案。采用共面转换模式并在液晶和反射板之间加入四分之一光延迟膜。通过使用参数空间表示法优化选择器件参数,获得了高反射率、低色散和宽视角的常白、常黑反射式显示模式。     

Theoretical and experimental study of nematic liquid crystaldisplay cells using the in-plane-switching mode

In this paper a two-dimensional (2-D) dynamic model, based on a tensor formulation and solved numerically by combining finite elements and finite differences, is proposed and used for analyzing nematic liquid crystal (LC) test cells with interdigital electrodes. We compare theoretical and experimental results concerning the switching behavior, response mechanism, and viewing angle characteristics of nematic LC pixel structures which use the in-plane-switching (IPS) mode. The good agreement observed between theory and experiment in terms of electro-optical properties validates our modeling and demonstrates its potential for design optimization. We show that the proposed LC test cells, using the in-plane-switching mode, ensure switching-ON and -OFF response times of 22 and 28 ms, respectively, and excellent viewing angle characteristics     

ADS模式低存储电容像素设计

高级超维场转换技术(Advanced Super Dimension Switch,简称ADS)是以宽视角技术为代表的核心技术统称,其显示模式过大的存储电容(C_(st))成为限制Dual Gate GOA 4K TV应用的主要因素。在较短的充电时间内,像素为了维持相同的充电率,需要降低C_(st)。本文采用一种双条形电极ADS结构(Dual Slit ADS),其中像素电极与公共电极交叠区域形成ADS结构,像素电极与公共电极间隔区域形成共面转换(IPS)结构,通过减少像素电极与公共电极的交叠面积,起到降低ADS模式C_(st)的目的。模拟结果表明:当ADS显示模式采用Dual Slit ADS设计时,像素的C_(st)可以下降30%~40%。实验结果表明:采用Low Cst Pixel ADS设计时,VGH Margin可以增大2.5 V,但受到像素电极和公共电极的对位影响,透过率下降5%。     

共面电场切换液晶显示器面板技术发展的回顾与展望

介绍IPS液晶显示技术的发展史、现况及对未来发展趋势的展望。在IPS技术克服了视角依存的显示基本需求特性,近来在动画质量与色彩再现稳定性方面亦大幅提升。现阶段开发重点则是着重于面板制造低成本、高生产良率和高对比特性,使其能与其它液晶电视技术匹敌。因此,我们成功开发了最具竞争力的新IPS模态,取名为AS-NOOC。与AS-IPS相比较,AS-NOOC具有省去一道Array基板侧的厚有机层制程的低制造成本优势,可大幅提高良率。并利用在彩色滤光片侧导入最佳化电极来同时优化面板亮、暗态的光学特性,有效提高对比度。     

In-Plane Switching Technology for Liquid Crystal Display Television

In-plane switching (IPS) technology used for liquid crystal display (LCD) TV is reviewed. Requirements of HD TV application are listed, and the main performances are compared among various competing display technologies. IPS LCD mode shows superior performances, satisfying the requirement for HD TV application.     

液晶电视材料进展

介绍LCD TV在垂直阵列（VA）、共面开关（IPS）和扭曲向列相（TN）等三种模式下，其工作电压和响应时间与液晶材料介电各向异性等主要参数的关系。探讨这三种模式对液晶材料主要参数的要求和这三种模式液晶材料发展状况。由Merck新开发的极性材料A、挥发性材料B以及强极性材料C可很好地改善LCD TV工作电压和响应时间。     

Transflective In-Plane Switching Liquid Crystal Display

A single cell gap, single gamma curve, and low operating voltage transflective liquid crystal display (LCD) using an in-plane switching (IPS) cell is proposed. In the IPS cell, the pixilated transparent indium tin oxide electrodes are on the top substrate and the reflectors are on the bottom substrate. The electro-optic properties of the transflective IPS LCD are calculated using three-dimensional simulation software. By optimizing the reflector width, the voltage-dependent transmittance and reflectance curves can be matched     

基于FFS架构实现宽窄视角切换

基于公共场合隐私保护的需求,宽窄视角可切换的液晶显示技术有着迫切的市场需求。现有宽窄视角切换技术不但增加了显示装置的厚度与成本,而且降低了原本宽视角模式下的显示效果。本文研究了一种基于负性液晶FFS模式的宽窄视角切换技术,它通过在彩色滤光片一侧形成高预倾角配向(40°～60°),在同侧第三电极施加弱电场时,液晶分子离轴方向具有较大相位延迟,形成大视角观看时的暗态漏光与对比度下降,实现窄视角显示模式。而同侧第三电极施加强垂直电场时,大的预倾角液晶分子因负介电各项异性使得倾角降低,可减少暗态漏光和提升对比度,实现宽视角显示模式。验证结果表明:宽视角模式时,其上下左右视角均可达到85°以上;而窄视角模式时,左右视角仅为40°,且具有较好的对称性。本技术结构简单,驱动灵活,在防窥显示领域具有很好的应用前景。     

Integrated cell and frame switching in ATM networks

Based on the per-VC queueing architecture, we propose a new technology to integrate cell and frame switching in asynchronous transfer mode (ATM) networks. We demonstrate that we can switch both fixed-length cells and variable-length frames inside the same switch at the same time. The insight is to recognize that we can store not only fixed-length cells, but also variable-length frames in each VC queue. The seamless integration of frame switching with cell switching will have a potential of merging frame relay with ATM     

基于浮置电极的高透过率蓝相液晶显示器件设计

传统平面内扭转(In-Plane Switching,IPS)模式的聚合物稳定蓝相液晶显示器件由于死区(Dead Zone)的存在,导致了透光率较低的问题。通过引入浮置电极(Floating Electrodes),增强死区上方的横向电场强度,可以解决这一问题,提高蓝相液晶显示器件的总体透过率。引入浮置电极的蓝相液晶显示器件的电光特性由Techwiz3D程序仿真予以分析。我们定量计算了电极尺寸、工作波长和电极错位对电光特性的影响。仿真结果表明,引入浮置电极的IPS模式蓝相液晶显示器件的透过率提高了约15%,对显示应用中常见的3种可见光波长(450nm,550nm,650nm)的总体透过率都达到了约90%。该新型器件结构能够显著提升蓝相液晶显示器件的透过率,使之在新一代显示技术发展和竞争过程中获得更大的优势地位。     

Surface Engineering of Carbon via Coupled Porosity Tuning and Heteroatom-Doping for High-Performance Flexible Fibrous Supercapacitors

Flexible fibrous supercapacitors (FFS) are considered the next-generation wearable energy storage devices because they provide reliable safety, eco-friendliness, and high power density. In particular, the FFS is desirable for application to wearable electronics because it can overcome disadvantages of the lithium-ion battery (LIB), such as the hazard of explosion and the complex manufacturing process. Nevertheless, the practical application of the FFS continues to be inhibited by the poor energy storage performance due to the limited specific surface area, poor electrical properties, and low wettability of the carbon fiber electrode. Herein, for the first time, the surface engineering of an FFS using nitrogen and fluorine codoped mesoporous carbon fibers (FFS-NFMCF) is described, and the synergistic effect of porosity tuning and heteroatom codoping upon the electrochemical performance is demonstrated. The resultant supercapacitor shows a high specific capacitance of 243.9 mF cm⁻² at a current density of 10.0 µA cm⁻² and good ultrafast cycling stability with capacitance retention of 91.3% for up to 10 000 cycles at a current density of 250.0 µA cm⁻². More interestingly, the FFS-NFMCF exhibits good mechanical properties and remarkable safety in practical application, thus demonstrating its feasibility for use in wearable electronic textiles.     

20.8 Gb/s GaAs LSI self-routing switch for ATM switching systems

An 8×8 self-routing hardware switch providing 20.8 Gb/s throughput has been developed for asynchronous transfer mode (ATM) switching systems. The basic architecture of this switch is a Batcher-Banyan network. A new mechanism for data processing and distributing high-speed signals is proposed. This switching system consists of three LSIs using a 0.5-μm gate GaAs MESFET technology. These LSIs are a switching network LSI for exchanging packet cells with eight cell channels, a negotiation network for screening of cells destined for the same output port, and a demultiplexer LSI for converting the cell streams from the switching network LSI to the eight streams per channel. These LSIs are mounted in a 520-pin multichip module package. The total number of logic gates is 13.3 k, and the power dissipation is 24 W. The switching system fully operates at a data rate of 2.6 Gb/s, and its throughput is 20.8 Gb/s     

Effect of the top electrode material on the resistive switching of TiO2 thin film

Effect of the top electrode (TE) metal on the resistive switching of (TE)/TiO₂/Pt structure was investigated. It was confirmed that the potential barrier height between the metal and TiO₂ is an important factor on the resistive switching characteristics. When high Schottky barrier was formed with the TiO₂ film, using Pt or Au as a top electrode, both stable URS (unipolar) and BRS (bipolar resistive switching) characteristics were observed depending on the current compliance level. In the case of Ag, which forms a relatively low Schottky barrier, only BRS characteristics were observed, regardless of the current compliance level. In the case of Ni and Al, which have similar work function as Ag, unstable URS and BRS at very low current compliance levels were observed due to a chemical reaction at the interface. For the Ti electrode, resistive switching was not observed, because the work function of Ti is lower than that of TiO₂ and TiO phase was formed at the interface (Ti/TiO_x contact is ohmic).     

Theory of switching phenomena in metal/semi-insulator/n-p silicon devices

The theory of switching is presented for a structure consisting of a p⁺-n junction and a metal electrode separated from the N-section of the p⁺-n junction by a semi-insulating (leaky) layer.

When a negative bias is applied to the electrode, the section of the n-layer under the electrode goes into deep depletion. In this mode, the current through the device is limited by generation in the deeply depleted region. This is the high-impedance or OFF state of the device.

At a sufficiently high voltage, the switching voltage, V_s, the p⁺-n junction is turned on by either avalanching in the n-layer or by the deep-depletion region extending through to the p⁺-n region (punch-through). When the junction turns on, the n-section goes from deep-depletion towards inversion. Thus, the voltage across the device decreaseswith a concomitant increase in the current through the device. This is the switching mode. The switching voltage may be tailored by varying the doping and/or width of the n-section.

Following switching, the device comes into the steady-state when the current through the insulating layer is equal to the current flowing across the p⁺-n junction. The I-V characteristic of this highly conducting (ON state) mode is determined principally by the I-V characteristic of the semi-insulating film. By suitable choice of material this portion of the characteristic can approach zero dynamic impedance, i.e. a near-vertical characteristic, characterized by a low holding voltage. Capacitance and switching characteristics of the device are also discussed.