河南理工大学HENAN POLYTECHNIC UNIVERSITY
英文文献翻译
English literature translation
学院：电气工程与自动化学院
专业班级：自动化 10-6班
姓名：梁朝伟
学号： 133******** 指导老师：刘德华
2014 年 6 月 6 日
The Research of the Large Screen Display System's LED Development
Along with computer technology's high speed development, LED (Light Emitting Diode) the screen display system takes after the television, the broadcast, the newspaper, the magazine “the fifth big media” marches into the social life fast each aspect. Its collection microelectronic technology, the computer technology, the information processing and management technology in a body, may the information through the writing, the design, the animation and the video frequency four forms demonstrates. With media and so on bank of television monitors, magnetism vane compares, the LED large screen display system has the design to be artistic, the color is sharp; The design, the color change are rich, are fast; The low power loss, the long life, the use cost low, work stably reliable and so on characteristics. It demonstrated the chart article angle of view is big, the apparent distance is far, thus has widely applied in the large-scale square, the commercial advertizing, the sports complexes, the information dissemination, the news issue, the securities trading; It also applies in the industrial control and the industry reassignment system, is advantageous each kind of parameter, the alarm point, the technical process demonstrates clearly perfect, may satisfy the different environment the need. The LED display monitor is one kind of use computer and the complex digital signal processing electron advertisements propaganda screen. Its screen body part by the microprocessor (is mainly monolithic integrated circuit) and the driving circuit control movement, demonstrated the image or the writing obtain by the computer edition software editor. Because the LED display monitor this kind of new generation information graphic display device has the demonstration design to be stable, the power loss is low, life long and so on characteristics, moreover it synthesized each kind of information graphic display device's strong point, and has overcome own insufficiency, because specially a display monitor may demonstrate that the different content, the display mode is rich. Therefore in the public area, it has the intense advertisements propaganda and the information transmission effect, already in the solid demonstrated day by day occupies the dominant position. The LED display monitor's prospects for
development are extremely broad, at present toward the high luminance, a higher weather fastness, the higher luminous density, the higher illumination uniformity, the reliability, the panchromatic direction is developing. Is composed of the different material's semiconductor can send out the different color the LED crystal spot. At present what applies is broadest is red, the green, yellow LED. But the blue color and the pure green LED development had already achieved the practical stage.
LED display monitor's classification
LED display monitor's classified LED display monitor is many kinds of technical synthesis application product, involves photoelectronics, the semiconductor device, the digit electronic circuit, the large scale integrated circuit, the monolithic integrated circuit and the microcomputer and so on each aspect, both has the hardware and to have software. After the LED display monitor is takes the broadcast, the television, the newspaper, the magazine another new communication media. At present the LED display monitor basis uses the place to be different, may divide into the outdoor screen and the indoor screen two kinds, its main difference is photo tube's illumination brightness is different. But acts according to the content which demonstrated different also to be possible to divide into the image screen and the writing screen two kinds, the image screen may the display image as well as multimedia, but writing screen main demonstration writing or simple fixed image. Display image's multimedia outdoor screens are the investment huge (reaches as high as several millions) the large-scale upscale equipment, main application in large-scale public place, image project and some important places. The LED display monitor's application involves to social economy many domains, already spread the transportation, the negotiable securities, the telecommunication, the advertisement, the propaganda and so on each aspect.
LED display monitor's trend of development
At present the LED display monitor's demonstration to the high luminance, a higher weather fastness, the higher illumination uniformity, a higher reliability, the panchromatic, the multimedia directions develops, system's movement, the operation and the maintenance also to the integration, the network, the intellectualized direction
develop. The 21st century's display technology will be the panel display time, the LED display monitor takes one of panel display leadership products to have a bigger development.
1. since the high luminance, entire color blue color and the green superelevation brightness LED product has appeared, the cost reduces fast year by year, causes the LED entire colored display monitor product cost to drop, the promoted speed speeds up. At the same time, along with control technology's development and the LED display monitor body stable enhancement, the entire colored LED display monitor's brightness, the color, white balanced achieves the quite ideal effect, definitely may satisfy the outdoors all-weather environmental condition request, moreover the image is clearer, is more exquisite, is sharper.
2. after standardization, standardized material, technology mature and market price basic balanced, the LED display monitor's standardization and the standardization will become a tendency which the LED display monitor develops. In recent years industry in development, after several price recedes the adjustment achieves basically balanced, the product quality, the system reliable and so on will become the main competition factor, this had the high request to the LED display monitor's standardization and the standardization. Profession standard and standard system's formation, IS09000 series standard application, causes the LED display monitor profession the development tends the order.
3. the product mix diversification along with the informationization society's formation, the information field is even more widespread, the LED display monitor's application prospect is broader. It is estimated that large-scale or the ultra-large LED display monitor will have the change for the mainstream product's aspect, will suit can have in the service industry characteristic and the specialized request small LED display monitor enhances greatly, will be richer face the information service domain's LED display monitor product class and the variety system, the part potential market demand and the application domain will have the breakthrough, like the mass transit, the parking lot, the dining, the hospital and so on comprehension service aspect's information display monitor demand will have a bigger enhancement.
Involves the mentality and the principle of work
This system basis classics' circuit design mentality, uses the design method from bottom to top, from the display panel to the actuation board, arrives at the control panel again, carries on the hardware programming, after debugging successfully, receives a telegram the source plate, finally completes the data transmission board and PC machine connects, carries on the PC software programming, completes the demonstration data the production, the extraction, processing, the transmission as well as the demonstration effect real-time control. Each module uses 8 LED lattices to lighten each line by the line scan form red, green, the traffic light, the demonstration writing and the image. The LED lattice's actuation, the decoding, the lock save and so on to be responsible by control panel's digital circuit. Its data reads by the monolithic integrated circuit from the memory, simultaneously the monolithic integrated circuit uses the interrupt mode, carries on the two-way communication through the RS-232 data line and PC machine, from the PC machine gain order or the data, and carries out the movement or the stored datum according to the order. Not only but PC machine carries on many machine serial port correspondences with many monolithic integrated circuits, but must be responsible for the writing input and the typesetting, the production lattice data or the order character, realize the man-machine interaction function.
Principle of work this article designs the large-scale LED display monitor becomes by the double primary color lattice LED combination, uses the line-by-line scanning the display mode to demonstrate red, green, the yellow three kind of color random lattice information. The display module uses the line-by-line scanning demonstration the way, its control system take monolithic integrated circuit AT89C52 as a core, uses 62256 memories to take the data-carrier storage, actuates 8*8 using latch 74HC377 and 8 group of line driver 2083The LED display module, simultaneously opens the serial port interrupt and superior PC machine carries on many machine correspondences. Through realizes display monitor's many kinds of animation pattern to the monolithic integrated circuit programming to demonstrate: Rolls the screen toward left, rolls the screen toward right, rolls the screen upwardly, rolls the screen downward, on rolls the screen toward left, on rolls the screen toward right, to the Zola curtain, pulls the curtain toward right, pulls the curtain upwardly,
pulls the curtain downward, to the right lateral, lightens in turn from left to right, from among to two nearby, lightens in turn. Animation speed adjustable: Divides into 100 grades, lowest is 1 fast, highest is 100 fast. The pattern color is diverse: The background achromatic color, the writing red/green/yellow, the background is red, the writing does not have/the yellow/green, the background green, the writing does not have/yellow/red, the background yellow, the writing does not have/the red/green. Moreover, but also increased several dozens kind of neon light effect animation. The PC machine on display control software may realize functions and so on Chinese character input, typeface choice, words change, and after carrying on the data processing, may in left side simulate the demonstration whole effect, simultaneously “sees namely obtained” demonstration in underneath preview region. Moreover, this control software also has additional functions and so on text designation, mouse localization, coordinate tracing, time date. PC machine realizes through the RS-232 connection with the demonstration part monolithic integrated circuit's correspondence, interrupts the real-time receive and the transmission data message using the monolithic integrated circuit serial port. Has also given dual attention to monolithic integrated circuit's antigambling ability in the system design, enhanced the systems operation reliability effectively.
Shines the second-level tube characteristic
The light emitter diode (light emitting diode, LED), is one kind turns the electrical energy the energy of light the special component, when the electric current achieves the threshold current, the light emitter diode breakover, along with electric current passing, produces the visible light. Light emitter diode's structure mainly ties the chip, the electrode and the optical system constitution by PN. After PN ties performs the direct voltage, P area's hole injection to the N area, N area's electron-injection to the P area, the electron which and the hole meet, pours into after mutually namely produces compound, these minority carriers injection which ties in PN produce the radiation with compound to shine. It is the original radiation illumination, does not need the high injection current to have the granule number reverse distribution, also does not need the optical resonator, the launch right and wrong coherent light. Describes the LED characteristic to have many parameters,
between these parameter's relations present misalignment. Therefore, describes these relations with the characteristic curve, has the use value in the project application. LED component's actuation
May know from the LED component's illumination mechanism, when exerts the direct voltage to the LED component, winds through component's forward current to cause its illumination. Therefore the LED actuation is must make its PN knot to be in the forward bias, simultaneously to control its luminous intensity, but must solve the forward current adjustment problem. The concrete drive type has [9] and so on direct-current actuation, constant flow actuation, pulse actuation and scanning actuation, in this system LED component's actuation for scanning actuation.
1. direct-current actuation. The direct-current actuation is the simple the actuation method. The LED operating point by supply voltage VCC, series resistance R and a LED component's voltage-current characteristic decided together. This drive type suits in the LED component are few, luminous intensity constant situation. For example on the public transportation uses for to demonstrate the “XX road fixedly” the inscription display monitor.
2. constant flow actuation. Is steep as a result of the LED component's forward characteristic, in addition component's dispersivity, causes in same the supply voltage and in the same limiting resistor's situation, the various components' forward current is not same, thus causes the luminous intensity difference. If carries on the constant flow actuation to the LED component, so long as the constant flow value is the same, the luminous intensity is quite close. Transistor's input level has the constant current characteristic, therefore may use the transistor to actuate LED.
3. pulse actuation. Using the human eye persistence, uses to the LED component repeatedly passes the power failure the way to cause it ignition, is the pulse drive type. The pulse actuation mainly has two aspect applications: Scanning actuation and duty factor actuation. The scanning actuation's main purpose is saves the driver, the simplified circuit. Selects when this method should pay attention to two questions: Acknowledging pulse electric current peak-to-peak value and choice recurrence rate. First, if wants to obtain with directs current the drive type suitable luminous intensity, pulse drive current mean value aI should be the same with direct-current actuation
magnitude of current oI.
4. scanning actuation. The scanning actuation through the digital logic electric circuit, causes certain LED component in turn break over, with saves the control driving circuit. The LED display monitor will shine the lamp according to the line according to a row arrangement, when the actuation also presses the line according to a row actuation. Under the scanning drive type may according to the line scan, according to a row control; May also according to a row scanning, according to a line of control. So-called “scanning” the meaning, is refers to a line of line of place to circulate puts through the entire line of LED component, no matter but this line of which row LED component whether should lighten, whether the concrete some row LED component should lighten, is responsible by the so-called row control circuit.
大屏幕显示系统的研究
LED的发展
随着计算机技术的高速发展，LED屏幕显示系统作为继电视、广播、报纸、杂志之后的“第五大媒体”正快速步入社会生活的各个方面。它集微电子技术、计算机技术、信息处理技术于一体，可以将信息通过文字、图案、动画及视频四种形式显示出来。与电视墙、磁翻板等媒体相比，LED大屏幕显示系统具有图案美观、色彩亮丽；图案、色彩变化丰富、快速；低功耗、长寿命、使用成本低、工作稳定可靠等特点。它显示的图文视角大、视距远，因而已广泛应用于大型广场、商业广告、体育场馆、信息传播、新闻发布、证券交易；它还应用于工业控制和工业调动系统，便于把各种参数、报警点、工艺流程显示得更加清晰完美，可以满足不同环境的需要。LED显示屏是一种利用计算机和复杂数字信号处理的电子广告宣传屏。它的屏体部分由微处理器（主要是单片机）和驱动电路控制运行，显示的图像或文字由计算机编辑软件编辑获得。由于LED显示屏这种新一代信息显示设备具有显示图案稳定、功耗低、寿命长等特点，而且它综合了各种信息显示设备的长处，并且克服了自身的不足，特别是由于一幅显示屏可以显示不同的内容，显示方式丰富。所以在公共场合，它具有强烈的广告宣传和信息传递效果，日趋在固体显示中占主导地位。LED显示屏的发展前景极为广阔，目前正朝着更高亮度、更高耐气候性、更高的发光密度、更高的发光均匀性、可靠性、全色化方向发展。由不同材料的半导体组成能发出不同色彩的LED晶点。目前应用最广的是红色、绿色、黄色LED。而蓝色和纯绿色LED的开发已经达到了实用阶段。
LED显示屏的分类
LED显示屏是多种技术综合应用的产品，涉及光电子学、半导体器件、数字电子电路、大规模集成电路、单片机及微机等各个方面，既有硬件又有软件。LED 显示屏是作为广播、电视、报纸、杂志之后的又一新传播媒体。目前LED显示屏根据使用场所不同，可以分为室外屏和室内屏两种，其主要区别是发光管的发光亮度不同。而根据所显示的内容不同也可以分为图像屏和文字屏两种，图像屏可以显示图像以及多媒体，而文字屏则主要显示文字或简单的固定图像。显示图像的多媒体室外屏是投资巨大(高达数百万)的大型高档设备，主要应用在大型公共
场所、形象工程和一些重要场所。LED显示屏的应用涉及到社会经济的许多领域，已经遍及交通、证券、电信、广告、宣传等各个方面。
LED显示屏的发展趋势
目前LED显示屏的显示向更高亮度、更高耐气候性、更高的发光均匀性、更高的可靠性、全色化、多媒体方向发展，系统的运行、操作与维护也向集成化、网络化、智能化方向发展。二十一世纪的显示技术将是平板显示的时代，LED显示屏作为平板显示的主导产品之一将有更大的发展。
1．高亮度、全彩化蓝色及绿色超高亮度LED产品出现以来，成本逐年快速降低，使LED全彩色显示屏产品成本下降，推广速度加快。同时，随着控制技术的发展和LED显示屏体稳定性的提高，全彩色LED显示屏的亮度、色彩、白平衡均达到比较理想的效果，完全可以满足户外全天候的环境条件要求，而且图像更清晰、更细腻、更亮丽。
2．标准化、规范化材料、技术的成熟及市场价格基本均衡之后，LED显示屏的标准化和规范化将成为LED显示屏发展的一个趋势。近几年业内的发展中，几番价格回落调整达到基本均衡后，产品质量、系统的可靠性等将成为主要的竞争因素，这就对LED显示屏的标准化和规范化有了较高的要求。行业规范和标准体系的形成，IS09000系列标准的应用，使LED显示屏行业的发展趋于有序。
3．产品结构多样化随着信息化社会的形成，信息领域愈加广泛，LED显示屏的应用前景更为广阔。预计大型或超大型LED显示屏为主流产品的局面将会发生改变，适合于服务行业特点和专业性要求的小型LED显示屏会有较大提高，面向信息服务领域的LED显示屏产品门类和品种体系将更加丰富，部分潜在市场需求和应用领域将会有所突破，如公共交通、停车场、餐饮、医院等综合服务方面的信息显示屏需求量将有更大的提高。
涉及思路及工作原理
本系统根据经典的电路设计思路，采用自下而上的设计方法，从显示板到驱动板，再到控制板，进行硬件编程，调试成功后接电源板，最后完成数据传输板与PC机相连接，进行PC软件编程，完成显示数据的生成、提取、处理、传输以及显示效果的实时控制。每个模块采用8个LED点阵以行扫描形式点亮各行的红、绿、红绿灯，显示文字和图像。LED点阵的驱动、译码、锁存等由控制板的数字电路负责。其数据由单片机从存储器中读取，同时单片机采用中断方式，通过
RS-232数据线与PC机进行双向通信，从PC机获取命令或数据，并按命令执行动作或者存储数据。而PC机不但与多个单片机进行多机串口通信，还要负责文字录入和排版，生成点阵数据或者命令字，实现人机交互功能。
工作原理
本文设计的大型LED显示屏由双基色点阵LED组合而成，采用逐行扫描的显示方式显示红、绿、黄三种颜色的任意点阵信息。显示模块采用逐行扫描显示的方式，其控制系统以单片机AT89C52为核心，采用62256存储器作为数据存储器，利用锁存器74HC377和8组线驱动器2083A驱动8*8的LED显示模块，同时开放串口中断与上位PC机进行多机通信。通过对单片机编程实现显示屏的多种动画模式显示：向左滚屏，向右滚屏，向上滚屏，向下滚屏，向左上滚屏，向右上滚屏，向左拉幕，向右拉幕，向上拉幕，向下拉幕，向右移，从左向右、依次点亮，从中间到两边、依次点亮。动画速度可调：分为100档，最低为1速，最高为100速。图案颜色多样：背景无色、文字红/绿/黄色，背景红色、文字无/黄/绿色，背景绿色、文字无/黄/红色，背景黄色，文字无/红/绿色。另外，还增加了几十种霓虹灯效果动画。PC机上的显示控制软件可以实现汉字录入、字体选择、字号更改等功能，并且在进行数据处理后，可以在左侧模拟演示整体效果，同时“所见即所得”的显示在下方预览区域。另外，该控制软件还具有文本选定、鼠标定位、坐标追踪、时间日期等附加功能。PC机通过RS-232接口实现与显示部分的单片机的通信，利用单片机串口中断实时接收和发送数据信息。在系统设计中还兼顾了单片机的抗干扰能力，有效地提高了系统运行的可靠性。
发光二级管特性
发光二极管(light emitting diode,LED)，是一种把电能变成光能的特种器件，当电流达到门限电流时，发光二极管导通，随着电流的通过，产生可见光。发光二极管的结构主要由PN结芯片、电极和光学系统构成。当在PN结上加以正向电压之后，P区的空穴注入至N区，N区的电子注入至P区，相互注入的电子与空穴相遇后即产生复合，这些少数载流子在PN结的注入和复合中产生辐射而发光。它是自发辐射发光，不需要较高的注入电流产生粒子数反转分布，也不需要光学谐振腔，发射的是非相干光。描述LED的特性有许多参数，这些参数之间的关系呈现非线性。因此，用特性曲线来描述这些关系，在工程应用中更具有使用价值。
LED器件的驱动
从LED器件的发光机理可以知道，当向LED器件施加正向电压时，流过器件的正向电流使其发光。因此LED的驱动就是要使它的PN结处于正向偏置，同时为了控制它的发光强度，还要解决正向电流的调节问题。具体的驱动方式有直流驱动、恒流驱动、脉冲驱动和扫描驱动等，本系统中LED器件的驱动为扫描驱动。
1．直流驱动。直流驱动是最简单的驱动方法。LED的工作点由电源电压VCC，串联电阻R和LED器件的伏安特性共同决定。这种驱动方式适合于LED器件较少，发光强度恒定的情况。例如公交车上使用的用来固定显示“XX路”字样的显示屏。
2．恒流驱动。由于LED器件的正向特性较陡，加上器件的分散性，使得在同样电源电压和同样限流电阻的情况下，各器件的正向电流并不相同，从而引起发光强度的差异。若对LED器件进行恒流驱动，只要恒流值相同，发光强度就比较接近。晶体管的输出特性具有恒流特性，所以可以用晶体管驱动LED。
3．脉冲驱动。利用人眼的视觉惰性，采用向LED器件重复通断电的方式使之点燃，就是脉冲驱动方式。脉冲驱动主要有两个方面的应用：扫描驱动和占空比驱动。扫描驱动的主要目的是节约驱动器，简化电路。采用这种方式时应该注意两个问题:确定脉冲电流幅值和选择重复频率。首先，要想获得与直流驱动方式相当的发光强度，脉冲驱动电流的平均值就应该与直流驱动的电流值相同。
4．扫描驱动。扫描驱动通过数字逻辑电路，使若干LED器件轮流导通，用以节省控制驱动电路。LED显示屏将发光灯按行按列布置，驱动时也按行按列驱动。在扫描驱动方式下可以按行扫描，按列控制；也可以按列扫描，按行控制。所谓“扫描”的含义，就是指一行一行地循环接通整行的LED器件，而不管这一行的哪一列的LED器件是否应该点亮，具体某一列的LED器件是否应该点亮，则由所谓的列控制电路来负责。