Electro-optical properties of a twisted hybrid aligned nematic mode for reflective liquid crystal displays

Abstract— A twisted hybrid aligned (THA) mode is proposed for reflective liquid-crystal displays. In the reflective configuration, a single polarizer and a reflective electrode are used to achieve electrooptical switching between the black and white states in the THA mode of a chiral nematic liquid crystal. Numerical simulations are performed to optimize the cell parameters such as the cell thickness and the amount of the twist in the hybrid geometry. The reflective THA mode is found to give wider viewing and faster response characteristics than a twisted nematic one. The role of an optical retardation film on device performance of such a reflective THA cell is also discussed.     

液晶显示多级汉字菜单的方法

:以 8 0 31单片机控制MGLS - 2 4 0 12 8液晶显示器为例 ,介绍利用CCDOS中的汉字库(HZK16 )实现多级汉字菜单显示的方法。当显示内容改变时 ,只需更改菜单参数 ,而不需更改程序 ,即可显示。     

An effective way to achieve full color cholesteric liquid crystal displays with single liquid crystal mixture and layer

Two‐step ultraviolet exposure method to achieve flexible color cholesteric LCD with single liquid crystal mixture and layer was proposed. The first step for polymer wall formation via photo‐polymerization induced phase separation and second step for color rendering with the photo‐sensitive chiral dopant were independently carried out without the interference of ultraviolet reaction using proper band‐pass filer. This display has good color performance and mechanical stability, which can be also driven by simplified driving circuit so that it would be a substantive solution for color flexible displays.     

便携式仪表液晶显示及按键电路的设计

液晶显示器在各种仪表的设计上被广泛的使用。本系统以AT89C51和LCM1601为核心部件,辅以必要的模拟电路并利用伟福E6000语言编写软件,实现按键键值的采集及驱动LCM1601显示功能。该系统由键盘、LCD显示、单片机控制模块等构成。本系统工作稳定,直观。     

Lab-on-a-display: a new microparticle manipulation platform using a liquid crystal display (LCD)

This paper reports a new portable microfluidic platform, “lab-on-a-display,” that microparticles are manipulated by optoelectronic tweezers (OET) on a liquid crystal display (LCD). The OET has been constructed by assembling a ground layer, a liquid chamber, and a photoconductive layer. Without lens or optical alignments, the LCD image directly forms virtual electrodes on the photoconductive layer for dielectrophoretic manipulation. The lab-on-a-display was first realized by a conventional monochromatic LCD module and a light source brighter than 5,000 lux. It was successfully applied to the programmable manipulation of 45 μm polystyrene beads; more than 100 particles were transported with an optical image-driven control, following the moving edge of the image at every moment. The effects of bead size and bias voltage on the manipulation speed were also investigated. Due to the portability and compatibility for disposable applications, this new platform has potential for programmable particle manipulation or chip-based bioprocessing including cell separation and bead-based analysis.     

Multimode fixed legend liquid crystal and electroluminescent display

A novel arrangement of colour-capable multi-legend displays is described. The electrodes are patterned to carry a continuous fixed message in positive or negative contrast. Colour is obtained either by dyes in guest-host type liquid crystal displays or by using a combination with thin film electroluminescent backlights. The main advantage is in its use in the future for keyboards where the keys can be used in a touch-sensitive interactive display mode.     

Evaluating sub-pixel functional defects of a display using an arbitrary resolution camera

An automatic optical inspection system to evaluate functional defects of sub-pixel elements in image displays is proposed, which is based on a single full-field imaging sensor. In order to circumvent sampling aliasing, the display is addressed with a set of grid patterns whose defocused optical images imitate a lower resolution display. The cross-talk between the sensor and the display primary colors is corrected by means of a linear transformation between their color-spaces. Dark and bright dots are located and quantified by applying a notch multi-band Fourier filter to the sensor images. The technique is simple, robust, and easily scalable, since only one image sensor is required, no moving parts are used, and the sensor can be reused to analyze increasing resolution displays.     

Cell‐gap and pretilt‐angle determination of a vertically aligned reflective liquid‐crystal display

Abstract— A simple method for determining the cell gap and pretilt angle of a vertically aligned reflective liquid‐crystal display has been developed. By extrapolating the phase‐retardation curve of the VA—LC cell in the high‐voltage regime, we can determine the cell gap. With this value for the cell gap and the low‐voltage part of the phase‐retardation curve, we can determine the pretilt angle.     

A new pixel design and a novel driving scheme for multi‐domain vertically aligned LCDs

Abstract— By using a new pixel design and a novel driving scheme that adds a bias electrode and a bias TFT to the ordinary pixel structure, a high‐contrast‐ratio and wide‐viewing‐angle LCD mode, refered to as the biased vertical‐alignment (BVA) mode, has been sucessfully developed. Compared to the published data on the PVA and MVA modes, the BVA mode has a distinct advantage of lower manufacturing cost due to the elimination of a lithographic process step that forms either ITO cuts or protrusions on the color‐filter substrates. The BVA mode requires ITO cuts on the TFT substrate similar to that for the PVA and MVA modes. The 15‐in. BVA‐mode XGA prototype exhibits a high contrast ratio of 1200:1 and high cell transmittance of 4.3%.     

Seventeen‐inch laser backlight in‐plane switching liquid crystal display with 8K, 120‐Hz driving,and BT.2020 color gamut

We have developed a 17‐inch laser backlight in‐plane switching liquid crystal display satisfying the main BT.2020 specifications, which are 8K, 120‐Hz driving, and a BT.2020 wide color gamut. The color gamut of the developed in‐plane switching liquid crystal display covers 98% of the BT.2020 wide color gamut, thanks to a laser backlight and appropriate color filters. The liquid crystal response time of 5 ms, which is sufficient for 120‐Hz driving, is achieved by adapting a faster in‐plane switching liquid crystal display, namely, the short‐range lurch control in‐plane switching liquid crystal display.     

一种无线异构网络的自适应垂直切换算法

针对移动节点在异构网络间切换性能不理想的问题,提出了一种自适应主动预测的垂直切换算法。采用一种面向当前应用程序的代价函数对可接入网络进行评估与选择;根据稳定周期、移动节点的运动速度及所处位置来自动调整切换执行时间,使移动节点能自适应地进行切换判决。仿真结果表明,该算法可以有效地减少切换延迟、分组丢失及切换次数,提高系统的切换性能,改善业务的QoS。     

An adaptive color image watermarking using RDWT-SVD and artificial bee colony based quality metric strength factor optimization

Image watermarking has emerged as a useful method for solving security issues like authenticity, copyright protection and rightful ownership of digital data. Existing watermarking schemes use either a binary or grayscale image as a watermark. This paper proposes a new robust and adaptive watermarking scheme in which both the host and watermark are the color images of the same size and dimension. The security of the proposed watermarking scheme is enhanced by scrambling both color host and watermark images using Arnold chaotic map. The host image is decomposed by redundant discrete wavelet transform (RDWT) into four sub-bands of the same dimension, and then approximate sub-band undergoes singular value decomposition (SVD) to obtain the principal component (PC). The scrambled watermark is then directly inserted into a principal component of scrambled host image, using an artificial bee colony optimized adaptive multi-scaling factor, obtained by considering both the host and watermark image perceptual quality to overcome the tradeoff between imperceptibility and robustness of the watermarked image. The hybridization of RDWT-SVD provides an advantage of no shift-invariant to achieve higher embedding capacity in the host image and preserving the imperceptibility and robustness by exploiting SVD properties. To measure the imperceptibility and robustness of the proposed scheme, both qualitative and quantitative evaluation parameters like peak signal to noise ratio (PSNR), structural similarity index metric (SSIM) and normalized cross-correlation (NC) are used. Experiments are performed against several image processing attacks and the results are analyzed and compared with other related existing watermarking schemes which clearly depict the usefulness of the proposed scheme. At the same time, the proposed scheme overcomes the major security problem of false positive error (FPE) that mostly occurs in existing SVD based watermarking schemes.     

Brightness and contrast of nematic liquid crystal bistable configuration displays

A photometer was used to measure the angular dependence of the brightness and contrast ratio of bistable configuration displays in both reflection and transmission modes. The essential result is that the field of view is not limited by any cut-off in the angular properties of the bistable configurations themselves, but is determined primarily by the conditions of illumination and properties of the reflector. The contrast ratio drops off only slightly for large viewing angles, and hence the acceptable field of view is determined primarily by the angular dependence of the brightness. The latter depends strongly on the nature of the illumination. For normally incident light, the full width at half maximum of the reflective display was 25° with a contrast ratio about 2.4. The transmission display was illuminated through a ground glass scattered by light normally incident on the ground glass. Under these conditions, the full width at half maximum was essentially the same as that of the ground glass alone, about 15dg and a contrast ratio of about 2. The photometer measurements of contrast ratio are in rough agreement with densitometer measurements of the absorption characteristics of the dichroic dye guest in the liquid crystal host in its parallel-aligned state.     

液晶化学传感器的关键技术与应用研究进展

液晶化学传感器是一种基于液晶分子排列取向发生变化来检测目标物存在与否的化学检测新装置。对液晶化学传感器的制备方法与应用进行了综述,并对该领域的发展方向进行了展望。     

Effect of correlated color temperature and illuminance on sustained attention collected via electroencephalography signals

This study aimed to explore the differences in the subjects' sustained attention under the impact of nine lighting conditions consisting of the combination of three commonly used correlated color temperature (CCT) (3300 K, 4300 K, and 5300 K) and illuminance levels (300 lx, 500 lx, and 750 lx) to provide guidance on the adjustment of CCT and illuminance level parameters for indoor lighting. We selected 24 physically and mentally healthy university students (12 male and 12 female) as the experimental subjects. The subjects were required to perform sustained attention to response task (SART) activities under the nine different lighting conditions and collected the alpha (α) waves (8–12 Hz) from the electroencephalography signals. Subsequently, the mean power spectral density of the α waves and various SART parameters were analyzed and tested. Finally, the effects of different CCT and illuminance levels on the subjects' attention were compared. With the increase in CCT, the attention level tended to increase linearly, whereas the attention level was the lowest at 300 lx and the highest at 500 lx and appeared as an inverted “U” shape. The subjects' attention level was the highest at the combination of CCT of 5300 K and illuminance level of 500 lx and the lowest at the combination of CCT of 3300 K and illuminance level of 500 lx. These results provide important data to elucidate the impact of lighting condition on attention.     

增强SH波电磁超声传感器信号的方法与实验

电磁超声传感器技术作为一种非接触无损测量方法,可用于恶劣工况的无损检测,尤其是可以实现水平剪切(SH)波的激励和接收。基于磁致伸缩效应的常规SH波电磁超声传感器信号较弱,为得到较强SH信号,改善信噪比,提出了一种增强电磁超声传感器信号的方法。该方法是在主永久磁铁闭合磁路上施加辅助永久磁铁,提高电磁超声线圈下部构件磁化强度,从而增强信号。实验证明:此方法可以使信号得到明显增强,并且有助于提高缺陷检测能力。     

群智能算法优化的结合熵的最大类间方差法与脉冲耦合神经网络融合的图像分割算法

针对最大类间方差准则下的图像分割结果携带原图信息量不足、实时性差和脉冲耦合神经网络（PCNN）模型中循环迭代次数难以确定的问题,提出了群智能算法优化的结合熵的最大类间方差法（OTSU-H）与PCNN融合的自动图像分割算法。首先,充分利用图像的灰度分布信息和相关信息,将图像信息中冗余度、竞争性以及互补性有效地融合,构造二维和三维观测空间,提出了OTSU-H准则的快速递归算法;其次,将快速递推算法的目标函数分别作为布谷鸟搜索（CS）算法、萤火虫算法（FA）、粒子群优化（PSO）算法和遗传算法（GA）四种群智能算法的适应度函数;最后,将优化之后的OTSU-H引入PCNN模型中自动获取循环迭代次数。实验结果表明,与原始的最大类间方差法（OTSU）、最大熵准则以及基于图论分割、像素的聚类分割和候选区域语义分割的图像分割算法相比,所提算法具有较好的图像分割效果,同时降低了计算复杂度,节约了计算机的存储空间,具有较强的抗噪能力。所提算法时间损耗少、不需要训练的特性使得算法的运用范围较广。     

Effect of vibration on eye,head and helmet movements while wearing a helmet‐mounted display

Previous research has demonstrated a loss of helmet‐mounted display (HMD) legibility for users exposed to whole body vibration. A pair of human factors studies was conducted to evaluate the effect of whole body vibration on eye, head, and helmet movements for seated users of a HMD while conducting simple fixation and smooth pursuit tracking tasks. These experiments confirmed that vertical eye motion can be demonstrated, that is consistent with the human visual systems' response to the vestibular–ocular reflex (VOR). Helmet slippage was also shown to occur, which could exacerbate loss of display legibility. The largest amplitudes in eye movements were observed during exposure to sinusoidal vibration in the 4–6 Hz range, which is consistent with the frequencies that past research has associated with whole‐body resonance and the largest decrease in display legibility. Further, the measured eye movements appeared to be correlated with both the angular acceleration of the user's head and the angular slippage of the user's helmet. This research demonstrates that the loss of legibility while wearing HMDs likely results from a combination of VOR‐triggered eye movements and movement of the display. Future compensation algorithms should consider adjusting the display in response to both VOR‐triggered eye and HMD motion.     

计算机网络在企业中的应用及实施

系统地介绍了计算机网络在企业中的应用 ,简单介绍了在某大厦中计算机网络的设计及局域网的施工以及在实践中应注意的问题。     

改进FCM和LFP相结合的白细胞图像分类

研究白细胞图像分类识别中有效的图像分割与特征提取方法,以提高白细胞图像的正确识别率.由于某些白细胞(粒细胞)中颗粒的存在,严重影响细胞核与细胞质区域的正确分割,通过将空间信息与核函数融入模糊C-均值聚类(FCM)算法,提出一种改进的FCM算法.应用该算法对白细胞图像进行分割,并采用数学形态学方法对分割后的图像进行处理,获得了很好的分割效果,解决了粒细胞的质核分割难题.对于细胞的纹理特征提取,通过对局部二值模式(LBP)中阈值参数的模糊化,建立了基于局部模糊模式(LFP)的纹理特征提取算法.运用本文方法进行图像分割和纹理提取,以支持向量机作为分类器,对CellAtlas的100幅白细胞图像进行了分类识别的实验,结果表明白细胞的正确识别率达到93％.