高动态范围图像采集及其双屏显示系统研究

为了更真实再现大范围亮度,获得更接近于真实的画面效果,设计并实现了高动态范围图像采集及其双屏显示系统.首先,研制了基于液晶光阀的光强连续选通成像系统,以实现高动态范围图像采集;其次,通过扩展动态范围图像处理算法将其合成高动态图像;最后,以液晶屏和LED组合作为显示源,双屏叠加,从而显示高动态范围图像.实验证明,所设计的系统图像对比度达到10 000∶1以上,功率减少了60.2％,LED亮度均匀性在95％以上.     

应用于硅基OLED微显示器的分段可调伽马校正

由于人类视觉系统感知的亮度与显示器实际显示的亮度为非线性关系,需要对显示器的视频数据进行伽马校正,使显示亮度适应人眼的感知需求。本文提出一种针对硅基OLED微型显示器的伽马校正方法。首先,基于人眼视觉的伽马特性,分析伽马校正的基本原理。然后,提出对输入视频数据进行位宽拓展达到非线性输出,并基于查找表和分段可调的线性差值算法实现伽马校正。最后,根据实际XGA039芯片发光情况调试校正参数以达到更优的显示效果。实验结果表明:XGA039芯片最大发光亮度为20 000cd/m~2,在伽马取值为2.2时,采用可调非均匀分段获得了较好的显示效果。所提出的伽马校正方法能够使视频图像的显示质量明显改进,且较传统方式在精度和实现面积上均有一定优势。     

基于亮度自适应分段的高动态图像色调映射算法

高动态范围图像(High Dynamic Range Image,HDRI)反映了真实场景的亮度值范围,具有较大的动态范围,而传统的显示设备的动态范围较低.若将高动态范围图像直接压缩到低动态范围显示设备时,可能会导致图像失真、细节丢失等问题.为解决上述问题,本文提出一种基于亮度自适应分段式的色调映射算法.首先,将高动态范围图像从RGB彩色空间转化到CIE XYZ彩色空间,使得亮度信息和彩色信息分离,并只对亮度信息进行处理且不改变颜色信息.其次,以对数亮度平均值作为关键值,从而得到划分区间段的低光区阈值和高光区阈值.然后,针对不同阶段亮度值的特点采用不同的亮度压缩算法,获得新的亮度分量.最后,恢复颜色信息,得到低动态范围图像.实验结果表明,本文的色调映射算法得到的结果整体亮度和细节效果较好.     

基于SG3525的液晶显示器平面背光源驱动电路设计

介质阻挡放电平面荧光灯(Flat Fluorescent Lamps,FFL)是一种新型的平面光源,在液晶显示器背光源方面具有很好的应用前景.研制了一种基于PWM控制芯片SG3525的FFL驱动电路,采用一种反激逆变结构,以直流80～100 V作为输入电压,产生出脉宽为3～4 μs,幅值为1 500～2 000 V的高压高频尖峰脉冲信号.本方案具有电路设计简单、灵活、效率高及成本低的优点.对FFL进行点屏试验的结果表明,设计出的电路可使FFL的平均亮度达到6 000 cd/m2,亮度均匀性达到80%以上.     

FED显示器的亮度控制

根据场发射显示器(FED)显示单元的调制特性和矩阵寻址方式特点,分析了其亮度控制的原理和实现方法.综合分析亮度控制的各种方法得出:电流驱动模式能保证亮度的均匀性,脉宽调制电流驱动应是线性灰度调制的最佳方案.     

空间紫外遥感光谱辐射计光谱辐亮度定标三种方法的比较

应用基于spectralon平面漫反射板和两种基于积分球的辐亮度共三种定标方法,标定了空间紫外遥感光谱辐射计的辐亮度响应度。初步尝试分析了每种方法的相对不确定度,指出漫反射板双向反射分布函数(BRDF)的测量不确定度和平面漫反射板亮度的计算不确定度是这三种定标方法比对中不一致的主要原因。定标数据比对显示,使用这三种定标方法得到的光谱辐射计辐亮度响应度在各自给定的相对不确定度范围以内(约3%)相符合。     

一种抑制关态漏电流和提高亮度稳定性的OLED微显示像素电路研究

OLED微显示像素驱动电路中,由于较小的存储电容和开关MOS管关态漏电流的影响,导致其存储电压和亮度不稳定.通过分析影响关态漏电流的主要因素,提出了一种多开关管串联和存储电容拆分相结合的办法以减小关态漏电流,并设计了一种含有两个开关管和两个存储电容的像素电路,该电路将关态漏电流由大于3 pA减小为0.4pA,存储电压和亮度稳定性得到了很大的改善,小亮度时一帧的亮度变化仅为0.18 cd/m2.电路可实现的最小OLED驱动电流为25 pA,像素亮度范围为1.82～217.37 cd/m2.     

FED矩阵扫描功率放大电路的研究

采用分立、集成及它们的混合方案来实现场致发射显示器矩阵扫描功率放大电路.分立式采用功率型MOS管组成的推挽功率放大电路来实现,集成式主要是基于PDP专用驱动芯片STV7697B,详细介绍了电路设计方案,混合式驱动方案结合了分立和集成两种驱动方式的优点,这个方案在FED的应用尚属首次.这些方案已经应用于25英寸彩色FED驱动系统中,能显示各种彩色视频图像,亮度达410 cd/ m2,对比度达1 010∶1.其中基于STV7697B的分立、集成混合驱动方案将在34英寸的彩色FED中得到进一步的应用.     

基于MPPM调光控制的混合可见光通信系统研究

在本文中,为适应照明的调光需求,提出了一种具 有高频谱效率的调光控制方案,这是也是可见光 通信(VLC)的关键需求。提出的方案将正交频分复用(OFDM)与多脉冲位置调制(MPPM) 相结合, 不仅支持高速可见光通信,同时满足了用户对照明源的亮度调节的需求。这种混合调制方法确保系统具有MPPM的调光功能,且引入的OFDM传输可以有效地提高频谱效率。更重要的是,MPPM跟OFDM的传输不会互相干扰,而且接收端对两种信号的检测互不干扰,实现简单。仿真结果表明,该 方案可以支持较宽的亮度范围,并支持高频谱无线光通信。     

用于显示的宽带多层介质半反镜

提出显示需要的一种宽带多层介质半反镜.采用对称膜系结构进行设计,并用共轭梯度法进行仿真优化,得到的多层介质半反镜在可见光波长范围都有很好的半反半透特性,并且对入射光的角度不敏感,从而保证了显示系统的亮度均匀性.     

体三维显示技术及其特点

体三维显示技术是三维显示技术的一个重要分支。首先对目前国内外较为成熟的体三维显示技术进行了分类和举例,然后对该技术的特点进行了总结。虽然目前的技术方案仍然存在一定的局限性,但是未来的新方案将会应运而生,并将逐步取代现在的二维显示。     

一种用于彩色胆甾相液晶显示的驱动电路

设计了一种用于彩色胆甾相液晶显示的驱动电路。电路根据P态刷新法和累计驱动法的驱动原理,实现了显示的多级灰度和彩色化,且利用了现有的商业液晶行列驱动芯片,因此具有结构简单,成本较低,易于实施等特点。     

Computer generation of colored planar patterns on TV-like rasters

With present technology, computer generation of color pictures on a television or on a computer output microfilm has become increasingly attractive. Shading algorithms for display of volumes or three-dimensional objects are readily available. Yet the display of essentially two-dimensional patterns calls for simpler, more natural schemes. Computer generation of colored two-dimensional patterns gives new directions to computer graphics software. The intention here is to state the issues and discuss the constraints. Solutions are derived from using known algorithms embedded in a frame especially designed to meet the constraints. Two different and complete schemes of colored pattern generation (CRPG), designed by the authors, are given as examples.     

Large-scale multiplexing of interferometric fiber-optic sensorsusing TDM and DWDM

This paper describes multiplexing schemes for interferometric fiber sensors based on time-division multiplexed and dense wavelength-division multiplexing using optical add/drop multiplexers. The results of an experimental arrangement, which is based on one of the architectures, is also presented. Topics include a discussion of the noise sources in the system, dynamic range, and a characterization of the distributed feedback fiber laser source noise. We show the crosstalk levels in the experimental arrangement to be between -47 and -76 dB depending on the mechanism involved. The multiplexing schemes demonstrate the potential to address at least 192 interferometric sensors through two fibers based on a system with six wavelengths with a phase resolution less than 20 μrad/√Hz. For application to sonar arrays, our analysis has shown that hydrophones multiplexed in this type of architecture would achieve ambient acoustic noise-limited pressure resolution with an in-water dynamic range up to 135 dB at frequencies up to 10 kHz. In general, these architectures would find application in systems requiring very large numbers of sensors with a minimum of telemetry cabling required     

Quantitative comparison of alternative sensory displays for mobility aids for the blind

This paper proposes a method to compare quantitatively various auditory display schemes communicating the course a blind traveler should follow to comply with information a blind mobility aid has acquired, and the optimal scheme is sought for that traveler. A computer system emulates different display devices which use amplitude modulation to indicate the error of a subject's location from the indicated course. The real-time Selspot-based TRACK system measures the location of the human subject in real time, and the error is presented to the subject via each of the emulated devices. The indicated course, human trajectory, and error are recorded in computer disk memory. The performance of the human in each task is evaluated by calculation of a transfer function of the human with each display and then using this transfer function as the criterion for comparison. The feasibility of designing the display schemes of blind mobility aids using this procedure is demonstrated. Thus, an optimal choice for the specific blind person can be made via this system before committing a particular mobility aid design to the lengthy development process.     

Computation of natural convection in channels with pin fins

In this paper, we numerically analyze the possibility of using buoyant flow in the display panel of a laptop for electronics cooling. Three-dimensional (3-D) channels with embedded pin fin arrays are analyzed using an unstructured finite volume method. Studies have been performed with a uniform heat flux boundary condition applied on the inner wall as well as for a constant inner wall temperature condition; the outer wall in all cases is exposed to the ambient. A single periodic module is selected in the lateral direction. In the axial mean flow direction, however, the entire height of the display channel is considered. Buoyancy has been modeled using Boussinesq approximation. A range of Rayleigh numbers, panel inclinations, and pin fin arrangements are considered. Local and global flow and heat transfer results are obtained including Nusselt numbers as well as local temperature and velocity fields. The results are useful in designing augmented cooling schemes in portable electronics.     

In‐Vehicle AR‐HUD System to Provide Driving‐Safety Information

Augmented reality (AR) is currently being applied actively to commercial products, and various types of intelligent AR systems combining both the Global Positioning System and computer‐vision technologies are being developed and commercialized. This paper suggests an in‐vehicle head‐up display (HUD) system that is combined with AR technology. The proposed system recognizes driving‐safety information and offers it to the driver. Unlike existing HUD systems, the system displays information registered to the driver's view and is developed for the robust recognition of obstacles under bad weather conditions. The system is composed of four modules: a ground obstacle detection module, an object decision module, an object recognition module, and a display module. The recognition ratio of the driving‐safety information obtained by the proposed AR‐HUD system is about 73%, and the system has a recognition speed of about 15 fps for both vehicles and pedestrians.     

A liquidic matrix-addressed display

Experiments with fluid logic circuits operated in an air-dyed water mode have demonstrated the basic validity of a large area, flat panel, matrix-addressed liquidic display. Such a display is conceptually attractive, since the switching, storage, and display functions are performed by the same medium. The measurements made have demonstrated that a reflective or emissive liquidic display, matrix addressed "a line at a time," has the following advantages: a flat panel geometry, a wide viewing angle, TV or better resolution, high contrast and brightness, a gray scale and color capability, speed (for TV resolution) from dc up to 3 frames/s, a range of sizes from small up to blackboard or larger, permanent memory, and high thermal, radiation, and shock resistance. The power requirements are less than (0.015/τ) W/cm²of display area, where τ is the frame time in seconds. Most importantly, the liquidic display can be constructed in a cheap integrated form. An elemental integrated liquidic display has been built with laminated layers of photoformed ceramic and has been successfully operated. Measurements made on the deflection of a fine stream of water (a polar liquid) by a nonuniform electric field have shown that this dielectrophoretic effect forms an elegant low-voltage transducer for the liquidic display. Such a transducer can be used on the periphery of a fluidically addressed matrix. Alternatively, because of its simplicity, it is feasible to have a threshold transducer at each element and electrically matrix address the transducers.     

三大电信运营商共建共营高校校园网设计方案

首先对校园网现状进行了分析,梳理出目前存在的问题及校方的潜在需求,然后结合现网实际情况,分别提出了学校统一认证和学校与运营商分开认证的方案,对于两种方案的实现原理和存在问题进行了逐一阐述,通过对比分析给出了相应的建议解决方案。