Analysis of electromagnetic radiation from a video output amplifierinside a monitor by using FDTD method

The finite-difference time-domain (FDTD) method is used to analyze the electromagnetic compatibility and interference (EMC and EMI) problems due to the electromagnetic radiation from a video output amplifier located inside a computer monitor. The multiple grid technique is implemented in the FDTD method to improve the computational efficiency. The video output amplifier is modeled by a rectangular iron container with an equivalent dipole antenna located at the center of one opened wall facing the cathode-ray-tube (CRT). The coupled electric fields inside and outside the monitor are calculated. It is found that higher values of coupled electric fields occur near the monitor screen. It is also found that the coupled electric fields outside the CRT region drop sharply in amplitude. Simulation results of coupled electric fields at a distance of 3 m from the monitor screen also comply with the FCC regulations. Calculation results also agree with the experimental data for coupled electric fields outside the monitor screen at a measured distance of 3 m     

新型LED背光源技术与应用实践研究

我国的科技发展迅速,背光源在各个领域也得到了广泛的应用.本文主要探讨LED背光源的技术以及应用.首先分析了LED背光源的技术,主要从技术、工艺、特点等方面进行分析,同时阐述了新型LED背光源在电视显示屏、机器视觉检测等领域的运用及关键要点,最后对全文进行了总结.     

High‐Resolution Monolithic Integrated Tribotronic InGaZnO Thin‐Film Transistor Array for Tactile Detection

Tactile detection is a crucial technology in many fields, such as electronic skin, touch screen control, human prostheses, and screen fingerprint identification. Tribotronics has demonstrated active mechanosensation from external mechanical stimuli, which greatly enriches the sensing mechanisms of tactile detection. In this work, a monolithic integrated indium‐gallium‐zinc‐oxide (InGaZnO or IGZO) thin‐film transistor (TFT) array is developed for high‐resolution tactile detection. By using the conventional semiconductor fabrication processes, each IGZO TFT cell in the array shows uniform electrical performance. In addition, the drain–source current can be individually tuned by the electrostatic potential generated by the contact electrification between a movable gate and the gate dielectric. The monolithic integrated array displays a relatively high resolution of 12 pixels per inch and can realize a millimeter‐level tactile perception and motion tracking. This work presents a facile and viable strategy toward micro/nano‐scale tribotronics, which can realize high‐resolution and large‐scale tactile detection.     

Enhancing HF received fields with large planar and cylindrical ground screens

Users of extended range HF (3 to 30 MHz) radar and communication systems employing the ionosphere desire signal reception at incidence angles near-grazing to the local earth tangent. For vertical polarization, the vanishing received fields at low incidence angles over dielectric earth may be increased by using large ground screens. In this paper a ground-screen formulation based on scattering techniques is developed. The ground screen is viewed as a scatterer in free space, excited by a plane wave. A Fresnel image wave is added to establish the air-earth interface. Formulations are developed for the semi-infinite screen and for the circular-cylinder surface segment screen. The semi-infinite screen is representative in performance to a round screen of radius equal to the distance from the edge of the semi-infinite screen at which the field is computed or measured. For a ground screen on a hill the cylindrical segment is appropriate. Computations for a simulated earth were made and corroborated by experimental simulation with scale models. Improvements in field strength of 7 to 14 dB or more can be achieved with large screens over no screen. "Relatively small" tilted or raised flat screens, and cylindrical segment screens, can give improvements equal to very large flat screens on the earth.     

天幕靶灵敏度的标定方法与试验

天幕靶探测灵敏度是天幕靶重要的性能指标.分析了天幕靶的工作原理和灵敏度机理,给出了光学镜头参数、被测弹丸长度与灵敏度之间的关系公式,提出了一种用小口径弹丸标定灵敏度的方法,推导了倍弹径数标定修正公式.通过气枪弹试验验证,文中研究的标定方法可行,给出的倍弹径数对实际使用具有明确的指导意义.     

A survey of electric and magnetic fields among VDT operators inoffices

The ambient electric and magnetic fields as well as the electromagnetic fields associated with video display terminals (VDTs) at 150 offices are measured. The aim of the study is to determine the general level of the various electromagnetic parameters in offices and establish a technical base for a case referent study of skin symptoms among VDT workers. The median value of the 50-Hz background field in the 150 offices is 0.07 μT. Seven of the offices have background levels higher than 0.5 μT, which is high enough to cause distortion of the picture on the screen. The dominant source for electric fields in the ELF range is electric equipment in the office, not the VDTs. The equivalent surface potential is less than 0.5 kV for 63% of the measured VDTs. The computer monitor is a major source of magnetic fields in the offices. The median value of the magnetic field in the ELF range in front of the VDT is 0.21 μT, and in the VLF range it is 0.03 μT     

Adaptive detector arrays for optical communications receivers

An optimal adaptive array receiver for use in groundbased optical communications is investigated. Kolmogorov phase screen simulations are used to generate realistic focal-plane distributions of the received optical fields in the presence of turbulence. The array detection concept reduces interference from background radiation by effectively assigning higher confidence levels at each instant of time to those detector elements that contain significant signal energy and suppressing those that do not. A simpler suboptimum structure that replaces the continuous weighting of the optimal receiver by a hard decision over each detector element is also described. It is shown that, for photon counting receivers observing Poisson distributed signals, performance improvements of up to 5 dB can be obtained over conventional single-detector photon counting receivers when observing turbulent optical fields in high background environments.     

Image theory for the unidirectionally conducting screen

Image theory is developed for electromagnetic sources in front of a planar unidirectionally conducting screen, made of ideally conducting parallel wires with thickness and interspace dimensions much smaller than the wavelength. Replacing the screen by the image sources gives the correct reflected and transmitted fields on the respective sides of the screen. The problem is solved through a decomposition of the original source in two parts, giving rise to fields TE and TM with respect to the direction of the wires. For the TE and TM source components, the images can be constructed from previous knowledge. For an electric dipole source, the images are seen to involve dipole and transmission-line sources     

Bandpass grids with annular apertures

A rigorous theory is developed for describing the diffraction of a plane wave by a doubly periodic array of annular apertures in a thick, perfectly conducting screen. Coaxial waveguide modes are used to describe the fields within each aperture, while the fields above and below the grid are written as plane wave expansions. Appropriate boundary conditions are applied at the upper and lower surfaces of the screen, and the method of moments is used to determine mode and wave amplitudes. Such a structure was found to exhibit excellent bandpass characteristics which can be adjusted by changing the size of the apertures and the thickness of the screen     

利用机器视觉的检测液晶屏幕坏点分析

本文针对液晶屏幕像素坏点检测当中出现的问题,根据机器视觉原理,利用HALCON以及VS2010作为开发平台,设计了液晶屏幕像素坏点自动检测系统.     

基于自适应局部增强的手机TFT-LCD屏Mura缺陷自动检测

针对手机屏幕图像整体亮度不均以及Mura缺陷对比度低等特点,提出一种基于自适应局部增强的Mura缺陷自动在线检测方法。首先对CCD相机采集的手机屏幕原始图像进行感兴趣区域提取、几何校正、滤波等预处理,获取图像中的屏幕区域,然后将屏幕区域划分为多个不重叠的像素块,并根据每个像素块的灰度分布特征,采用自适应局部增强算法自动识别并定位图像中的Mura区域,最后考虑到Mura缺陷大小的不确定,提出采用多层级分块的方式对屏幕区域进行检测,提高算法鲁棒性。实验结果表明,相较现有多种屏幕缺陷自动检测算法,本文方法能更准确有效地识别手机屏幕中的Mura缺陷,且覆盖率和误检率分别为91.17%和5.84%。     

Invited Paper Beam diffraction by a random phase screen

An electromagnetic or acoustic beam incident on a randomly rough boundary is modelled as a random phase screen. The particular case of a gaussian beam incident on a screen whose phase is a gaussian process is considered in detail. The technique, which uses Papoulis' extension of Woodward's ambiguity function for random fields, is finally applied to arbitrary transmitting and receiving antennas (or transducers) coupled through a phase screen whose statistics are arbitary but stationary     

玻璃结构电容式触摸屏邦定工艺及设备

近年来玻璃结构电容式触摸屏广泛应用于各个领域,邦定工艺是玻璃结构电容式触摸屏生产制造过程中的关键工艺。介绍了玻璃结构电容式触摸屏的邦定工艺流程,并对常用的几类邦定设备进行了分析、比较。     

红外烟幕对红外系统干扰的效能评估

在红外烟幕对红外成像和制导起到重要干扰作用认识的基础上,计算了在红外烟幕干扰条件下,红外接收系统的探测概率,并分析了红外烟幕对接收系统的干扰效果,其次研究了红外烟幕对红外成像制导的干扰,最终得出相关结论．     

Plane wave reflection from a rectangular-mesh ground screen

The theory of scattering of electromagnetic plane waves of arbitrary incidence and polarization from an infinite rectangular-mesh ground screen is treated. The screen is composed of thin wires of circular cross section, and is parallel to the interface between two homogeneous media. The theoretical results for parallel-wire screens are obtained in the limit of large wire spacing for one dimension of the mesh screen. Results presented for incident parallel polarized plane waves indicate that both the parallel-wire and mesh screens may exhibit a change in reflecting properties as the plane of incidence is varied from the wire axis direction. In addition, it is shown that the parallel-wire screen can produce appreciably higher cross-polarized fields than a square-mesh screen of the same wire spacing.     

8MM Radiometric Simulation Detection Based on Optical Image

Widely applied in the fields of guidance and remote sensing, millimeter wave radiometer is a typical passive detection system. Radiometric simulation detection based on optical image is presented as a new approach of target detection. In this paper, we mainly discuss the design proposal of software structure and the output results of simulation system. We have developed 8mm radiometric target detection simulation system, which exactly simulated radiometric target detection by the working procedure, simulation environment and technical parameters. All adoptive data is measured and collected by our lab for many years. So the result is acceptable. It is greatly helpful to detect specific target and improve radiometric hardware design.     

Electromagnetic deposition in an anatomically based model of manfor leakage fields of a parallel-plate dielectric heater

An anatomically based 5628-cell model of a human being was used to calculate local, layer-averaged, and whole-body-averaged specific absorption rates and internal RF currents at 27.12 and 40.68 MHz for spatially variable electromagnetic fields of a parallel-plate applicator representative of RF dielectric heaters used in industry. The conditions of exposure of the man model considered are: isolated from ground, shoe-wearing condition, feet in contact with ground, and an additional grounded top plate 13.1 cm above the head to simulate screen rooms that are occasionally used for RF heaters. Since peak E fields as high as 1000-2700 V/m have been measured at locations typically occupied by the operator, significant internal RF currents on the order of 0.5-2.3 A are projected for the operators. Measurements of the foot currents at 27.12 and 40.68 MHz for a human subject are in reasonable agreement with the calculated values for the various conditions of exposure     

TE scattering from a slit in a thick conducting screen: revisited

TE plane-wave scattering from a slit in a thick conducting screen is reexamined. The boundary conditions are enforced to obtain simultaneous equations for the transmitted field inside the thick conducting screen. The simultaneous equations are solved to represent the transmitted and scattered fields in series forms. An approximate series solution for transmission is obtained in closed form which is valid for the high-frequency scattering regime     

屏幕共享技术及其在多媒体技术中的应用

介绍了屏幕共享技术的起源、发展和近况，着重分析了3类常见屏幕共享技术的具体实现方式和主要产品，并且讨论了屏幕共享在远程教学、监控系统及网络多媒体领域中的应用以及在该领域的研究成果和产品。     

PROBE-HOLE FIELD EMISSION MICROSCOPE SYSTEM CONTROLLED BY COMPUTER

A probe-hole field emission microscope system,controlled by the Apple Ⅱ computer,has been developed and operated successfully for measuring the work function of a single crystalplane.The detection screen,the phototube and the amplifier are combined for measuring theprobe-hole current.The combination is calibrated and the calibrated data are used in the com-puter program.The high voltage on the viewing screen is adjusted by using a D/A converter.The total current and the probe-hole current are acquired by using an A/D converter.A programin BASIC is used for processing all data and the Fowler-Nordheim plot parameters are given.Work functions of single crystal planes can then be calculated;as examples,the work functionson the clean W(100)and W(111)planes are measured to be 4.67 eV and 4.45 eV,respectively.