LED中英文翻译论文

PAGEword文档可自由复制编辑FirstLEDSummary一LED概述LED(LightEmittingDiode),light-emittingdiode,isasolidstatesemiconductordevices,whichcanbedirectlyconvertedintoelectricitytolight.LEDistheheartofasemiconductorchip,thechipisattachedtooneendofastent,isthenegativeside,theotherendofthepowerofthecathode,theentirechippackagetobeepoxyresin.Semiconductorchipiscomposedoftwoparts,partoftheP-typesemiconductor,itinsidethehole-dominated,theothersideistheN-typesemiconductor,hereismainlyelectronic.Butlinkingthetwosemiconductors,amongthemtheformationofa"PNjunction."Whenthecurrentthroughthewiresroleinthischip,willbepushinge-P,Pzoneintheholewithelectroniccomposite,andthentobeissuedintheformofphotonenergy,andthisistheprincipleofLEDluminescence.Thewavelengthoflightthatisthecoloroflight,isformedbythePNjunctionofthedecisionsofthematerial.LED（LightEmittingDiode），发光二极管，是一种固态的半导体器件，它可以直接把电转化为光。LED的心脏是一个半导体的晶片，晶片的一端附在一个支架上，一端是负极，另一端连接电源的正极，使整个晶片被环氧树脂封装起来。半导体晶片由两部分组成，一部分是P型半导体，在它里面空穴占主导地位，另一端是N型半导体，在这边主要是电子。但这两种半导体连接起来的时候，它们之间就形成一个“P-N结”。当电流通过导线作用于这个晶片的时候，电子就会被推向P区，在P区里电子跟空穴复合，然后就会以光子的形式发出能量，这就是LED发光的原理。而光的波长也就是光的颜色，是由形成P-N结的材料决定的。SecondLEDhistoryanddevelopment50yearsago,peoplehavetounderstandsemiconductormaterialscanproducelightofthebasicknowledge,thefirstcommercialdiodesin1960.EnglishistheLEDlightemittingdiode(LED)acronym,anditsbasicstructureisanelectroluminescentsemiconductormaterials,placedinawirerack,thensealedwithepoxyresinaround,thatis,solidpackage,Therefore,theprotectionoftheinternalbatteriescanplaytheroleofline,sotheseismicperformanceLEDgood.LEDisthecoreoftheP-typesemiconductorandcomponentsoftheN-typesemiconductorchips,theP-typesemiconductorandN-typesemiconductorbetweenatransitionlayer,calledthePNjunction.InsomesemiconductormaterialsinthePNjunction,theinjectionofasmallnumberofcarrier-carrierandthemajorityoftheextratimewillbeintheformoflightenergytorelease,thusthepowertodirectconversionofsolarenergy.PNjunctiononreversevoltage,afewhard-carrierinjection,itisnotluminous.Thisuseofinjectionelectroluminescentdiodesisproducedbytheprincipleoflight-emittingdiodes,commonlyknownasLED.Whenitinapositivestateofthework(thatis,atbothendswithforwardvoltage),thecurrentflowsfromtheLEDanode,cathode,semiconductorcrystalsontheissuefromtheultraviolettoinfraredlightofdifferentcolors,lightandthestrengthofthecurrents.InstrumentsusedforthefirstLEDlightsourceinstructions,butallkindsoflightcoloredLEDlightsintrafficandlargescreenhasbeenwidelyapplied,haveaverygoodeconomicandsocialbenefits.The12-inchredtrafficlightsasanexample,isusedintheUnitedStateshavelonglife,low-efficiency140wattincandescentlampasalightsource,itproduced2,000lumensofwhitelight.Theredfilter,theloss-90percent,only200lumensofredlight.Inthelightofthenewdesign,Lumiledscompanieshave18redLEDlightsource,includingthelossofcircuit,atotalpowerconsumptionof14wattstogeneratethesameopticaleffect.AutomotiveLEDlightsisalsothesourceofimportantareas.Forgenerallighting,peopleneedmorewhitelightsources.The1998whiteLEDsuccessfuldevelopment.ThisistheGaNLEDchipandYttriumAluminumGarnet(YAG)packagetogethercause.GaNchipoftheBlu-ray(λp=465nm,Wd=30nm),madeofhigh-temperaturesinteringoftheCe3+YAGphosphorsexcitedbythisBlu-rayafterirradiatingayellow,thepeak550nm.Blue-chipinstalledintheLED-basedWanxingreflectioninthecavity,coveredwitharesinmixedwithYAGthinlayer,about200-500nm.LED-basedtabletsissuedbytheBlu-rayabsorptionpartofthephosphor,thephosphoranotherpartoftheBlu-rayandayellowlightmixed,canbeawhite.Now,theInGaN/YAGwhiteLED,YAGphosphorbychangingthechemicalcompositionofthephosphorlayerandadjustthethicknessofthe3500-10000Kcolortemperaturecanbecoloredwhite.ThisblueLEDthroughthemethodbywhite,constructedsimple,low-cost,hightechnologyismature,sousethemost.ThedevelopmentofLEDdisplaycanbedividedintothefollowingphases:firstphase1990to1995,mainlymonochromeand16colorgraphicsscreen.Usedtodisplaytextandsimpleimages,mainlyusedinrailwaystations,financialsecurities,banks,postofficesandotherpublicplaces,aspublicinformationdisplaytools.Thesecondstageisfrom1995to1999,therehavebeen64,256levelgray-scaletwo-colorvideoscreen.Videocontroltechnology,imageprocessing,opticalfibercommunicationtechnologyapplicationswillenhancetheLEDdisplaytoanewlevel.LEDdisplaycontrolLSIchipsspecialatthistimedevelopedbydomesticcompanies,andcanbeapplied.Thethirdstage,from1999,red,puregreen,blueLEDinbulkintoChina,whiledomesticenterprisesin-depthresearchanddevelopmentwork,usingred,green,andblueLEDproductionoffull-colordisplayhasbeenwidelyused,pouredintosportsstadiums,conventioncenters,squaresandotherpublicplaces,whichwillbringthedomesticlarge-screenfull-colorera.WiththerapiddevelopmentofLEDmaterialsmarket,surfacemountdeviceisavailablefrom2001,mainlyusedinindoorfullcolor,anditshighbrightness,colorful,lowtemperaturecharacteristics,thepointspacingcanbeadjustedbydifferentpriceRequirementswereaccepted,injusttwoyearstime,productsaleshavemorethan300millionyuan,surfacemountfull-colorLEDdisplayapplicationmarketenteredthenewcentury.Tomeetthe2008OlympicGames,"downsizing"plan,Liarddevelopedasurfacemountdualcolordisplays,alotoftimeforthetrainingcenterandgamescoring.FullcolorinOlympicvenues,inordertotighteninvestment,fullcolorwayismostlydetachable,liveduringtheOlympicGamesasatoolcanbeusedforrentalaftertheevent,astheperformanceofnationalpoliciessuchaspublicplaces,toolsreleasedbyInthiswaycostrecoveryassoonaspossible.Onthemarket,China'saccessiontoWTO,Beijing'ssuccessfulOlympicbidandsoon,intothedevelopmentofLEDdisplayindustry,anewopportunity.DomesticLEDdisplaymarketcontinuestogrow,currentlyinthedomesticmarket,domesticLEDdisplaymarketshareofnearly95%.LEDdisplaytheinternationalmarketcapacityisexpectedto30%ayeargrowthrate.Currently,LEDdisplaymanufacturersconcentratedprimarilyinJapan,NorthAmerica,ChinaLEDmanufacturersinwhichtheinsignificantshareofexports.Accordingtoincompletestatistics,theworld,thereareatleast150manufacturersfullcolor,inwhichproductsarecomplete,thelargercompanyhassome30orso.二LED历史及发展现状50年前人们已经了解半导体材料可产生光线的基本知识，第一个商用二极管产生于1960年。LED是英文lightemittingdiode（发光二极管）的缩写，它的基本结构是一块电致发光的半导体材料，置于一个有引线的架子上，然后四周用环氧树脂密封，即固体封装，所以能起到保护内部芯线的作用，所以LED的抗震性能好。发光二极管的核心部分是由P型半导体和N型半导体组成的晶片，在P型半导体和N型半导体之间有一个过渡层，称为P-N结。在某些半导体材料的PN结中，注入的少数载流子与多数载流子复合时会把多余的能量以光的形式释放出来，从而把电能直接转换为光能。PN结施加反向电压时，少数载流子难以注入，故不发光。这种利用注入式电致发光原理制作的二极管叫发光二极管，通称LED。当它处于正向工作状态时（即两端加上正向电压），电流从LED阳极流向阴极时，半导体晶体就发出从紫外到红外不同颜色的光线，光的强弱与电流有关。最初LED用作仪器仪表的指示光源，后来各种光色的LED在交通信号灯和大面积显示屏中得到了广泛应用，产生了很好的经济效益和社会效益。以12英寸的红色交通信号灯为例，在美国本来是采用长寿命、低光效的140瓦白炽灯作为光源，它产生2000流明的白光。经红色滤光片后，光损失90%，只剩下200流明的红光。而在新设计的灯中，Lumileds公司采用了18个红色LED光源，包括电路损失在内，共耗电14瓦，即可产生同样的光效。汽车信号灯也是LED光源应用的重要领域。对于一般照明而言，人们更需要白色的光源。1998年白光的LED开发成功。这种LED是将GaN芯片和钇铝石榴石（YAG）封装在一起做成。GaN芯片发蓝光（λp=465nm，Wd=30nm），高温烧结制成的含Ce3+的YAG荧光粉受此蓝光激发后发出黄色光射，峰值550nm。蓝光LED基片安装在碗形反射腔中，覆盖以混有YAG的树脂薄层，约200-500nm。LED基片发出的蓝光部分被荧光粉吸收，另一部分蓝光与荧光粉发出的黄光混合，可以得到得白光。现在，对于InGaN/YAG白色LED，通过改变YAG荧光粉的化学组成和调节荧光粉层的厚度，可以获得色温3500-10000K的各色白光。这种通过蓝光LED得到白光的方法，构造简单、成本低廉、技术成熟度高，因此运用最多。LED显示屏的发展可分为以下几个阶段：第一阶段为1990年到1995年，主要是单色和16级双色图文屏。用于显示文字和简单图片，主要用在车站、金融证券、银行、邮局等公共场所，作为公共信息显示工具。第二阶段是1995年到1999年，出现了64级、256级灰度的双基色视频屏。视频控制技术、图像处理技术、光纤通信技术等的应用将LED显示屏提升到了一个新的台阶。LED显示屏控制专用大规模集成电路芯片也在此时由国内企业开发出来并得以应用。第三阶段从1999年开始，红、纯绿、纯蓝LED管大量涌入中国，同时国内企业进行了深入的研发工作，使用红、绿、蓝三原色LED生产的全彩色显示屏被广泛应用，大量进入体育场馆、会展中心、广场等公共场所，从而将国内的大屏幕带入全彩时代。随着LED原材料市场的迅猛发展，表面贴装器件从2001年面世，主要用在室内全彩屏，并且以其亮度高、色彩鲜艳、温度低的特性，可随意调整的点间距，被不同价位需求者所接受，在短短两年多时间内，产品销售额已超过3亿元，表面贴装全彩色LED显示屏应用市场进入新世纪。为了适应2008年奥运会的“瘦身”计划，利亚德开发了表面贴装双基色显示屏，大量用于训练馆和比赛计时计分系统。在奥运场馆全彩屏方面，为紧缩投资，全彩屏大部分采用可拆卸方式，奥运期间可作为实况转播工具，赛事结束后可用于租赁，作为演出、国家政策发布等公共场合应用工具，通过这种方式可尽快收回成本。就市场而言，中国加入WTO、北京申奥成功等，成为LED显示屏产业发展的新契机。国内LED显示屏市场保持持续增长，目前在国内市场上，国产LED显示屏的市场占有率近95%。国际上LED显示屏的市场容量预计以每年30%的速度在增长。目前，LED显示屏的主要制造厂商集中在日本、北美等地，我国LED制造厂商出口的份额在其中微不足道。据不完全统计，世界上目前至少有150家厂商生产全彩屏，其中产品齐全，规模较大的公司约有30家左右。ThirdLEDadvantagesConductorlight-emittingdiode(LED)asathird-generationsemiconductorlightingsource.Thisfantasticproducthasalotofadvantages:(1)efficientlight:spectraofalmostallconcentratedinthevisiblelightfrequency,theefficiencycanreach80%-90%.Theluminousefficiencyofincandescentvisiblelightefficiencyofalmost10%-20%only.(2)highqualityoflight:notasaresultofspectrumUVandinfrared,thereisnoheat,noradiation,istypicallyagreenlightillumination.(3)energyconsumptionofthesmall:singlepowergenerally0.05-1w,throughtheclustercanbetailoredtomeetdifferentneeds,andwasteverylittle.Asalightsource,underthebrightnessinthesamepowerconsumptionofonlyordinaryincandescent1/8-10.(4)longlife:fluxattenuationto70%ofthestandardlifeexpectancyis100,000hours.Asemiconductorlightcanbeusedundernormalcircumstances50years,evenifthelonglifeofthepeople,lifewillbeuseduptotwolights.(5)durableandreliable:Notungstenwire,glassandothereasilydamagedcomponents,non-normalretirementrateisverysmall,verylowmaintenancecosts.(6)theapplicationofflexibility:smallsize,canflatpack,easytodevelopintoashortthinproducts,makepoint,line,facevariousformsofspecificapplications.(7)Security:workingvoltage1.5-5vorlessinbetweenthecurrent20-70mAinbetween.(8)green:recyclablewaste,nopollution,unlikefluorescentlampscontainingmercuryasingredients.(9)responsetimeisshort:toadapttofrequentandhigh-frequencyswitchingoperationofoccasions.三LED优点导体发光二极管(LED)作为第三代半导体照明光源。这种产品具有很多梦幻般优点：(1)光效率高：光谱几乎全部集中于可见光频率，效率可以达到80%-90%。而光效差不多的白炽灯可见光效率仅为10%-20%。(2)光线质量高：由于光谱中没有紫外线和红外线，故没有热量，没有辐射，属于典型的绿色照明光源。(3)能耗小：单体功率一般在0.05-1w，通过集群方式可以量体裁衣地满足不同的需要，浪费很少。以其作为光源，在同样亮度下耗电量仅为普通白炽灯的1/8-10。(4)寿命长：光通量衰减到70%的标准寿命是10万小时。一个半导体灯正常情况下可以使用50年，即使长命百岁的人，一生最多也就用2只灯。(5)可靠耐用：没有钨丝、玻壳等容易损坏的部件，非正常报废率很小，维护费用极为低廉。(6)应用灵活：体积小，可以平面封装，易开发成轻薄短小的产品，做成点、线、面各种形式的具体应用产品。(7)安全：单位工作电压大致在1.5-5v之间，工作电流在20-70mA之间。(8)绿色环保：废弃物可回收，没有污染，不像荧光灯一样含有汞成分。(9)响应时间短：适应频繁开关以及高频运作的场合FourthClassificationofLEDdisplay1,colorbycolorcanbedividedinto

Single-colordisplay:Singlecolor(redorgreen).

Two-colordisplay:redandgreendual-color,256grayscalelevels,candisplay65,536colors.

Full-colorscreen:red,green,bluecolor,256grayscalefullcolordisplaycandisplaymorethan16millionkindsofcolors.

2,accordingtodisplaydeviceclassification

LEDDigitalDisplay:7segmentdisplaydevicesforthedigitalcontrolcode,suitableforproductionoftheclockscreen,theinterestratescreens,showingthenumberofelectronicdisplay.

LEDdot-matrixgraphicdisplay:displaydeviceisarrangedbyanumberofuniformcompositionofthedot-matrixLEDdisplaymodules,suitableforbroadcasttext,imageinformation.

LEDvideodisplay:displaydevicesareformedbyanumberoflight-emittingdiodesthatcandisplayvideo,animationandothervideofiles.

3,byusingtheoccasioncategories

IndoorDisplay:LEDspotssmaller,generalΦ3mm-Φ8mm,showsthegeneralareaofafewtomorethantensquaremeters.

OutdoorDisplay:dozensofsquaremetersinsizetoseveralhundredsquaremeters,highbrightness,canworkinthesun,withwind,rain,waterresistant.

4,classifiedaccordingtolightspotdiameter

Indoorscreen:Φ3mm,Φ3.75mm,Φ5mm,

Roomexternalscreen:Φ10mm,Φ12mm,Φ16mm,Φ19mm,Φ20mm,Φ21mm,Φ22mm,Φ26mm

Roomexternalscreenasthebasicunitoflightemittingtube,LEDtubeprincipleisasetofred,green,andbluelight-emittingdiodesealedinaplasticbarrelandjointlydevelop

5,Displayastatic,horizontalscroll,verticalscrollandflipdisplay.Oneblockmodulecontroldrive12(uptocontrol24)8X8DotMatrix,atotalof16X48dotmatrix(or32X48dotmatrix),isasingleblockofMAX7219(orPS7219,HD7279,ZLG7289and8279,andthelikeLEDdisplaydrivermodule)12times(or24times)!Canuse"cascade"approachthecompositionofanylargedotmatrixdisplay.Effects,goodpowerconsumption,andtheMAX7219circuitthantheuseoflowercost.

四LED显示屏的分类

1、按颜色基色可以分为

单基色显示屏:单一颜色（红色或绿色）。

双基色显示屏：红和绿双基色，256级灰度、可以显示65536种颜色。

全彩色显示屏：红、绿、蓝三基色，256级灰度的全彩色显示屏可以显示一千六百多万种颜色。

2、按显示器件分类

LED数码显示屏：显示器件为7段码数码管，适于制作时钟屏、利率屏等，显示数字的电子显示屏。

LED点阵图文显示屏：显示器件是由许多均匀排列的发光二极管组成的点阵显示模块，适于播放文字、图像信息。

LED视频显示屏：显示器件是由许多发光二极管组成，可以显示视频、动画等各种视频文件。

3、按使用场合分类

室内显示屏：发光点较小，一般Φ3mm--Φ8mm，显示面积一般几至十几平方米。

室外显示屏：面积一般几十平方米至几百平方米，亮度高，可在阳光下工作，具有防风、防雨、防水功能。

4、按发光点直径分类

室内屏：Φ3mm、Φ3.75mm、Φ5mm、

室外屏：Φ10mm、Φ12mm、Φ16mm、Φ19mm、Φ20mm、Φ21mm、Φ22mm、Φ26mm

室外屏发光的基本单元为发光筒，发光筒的原理是将一组红、绿、蓝发光二极管封在一个塑料筒内共同发

5、显示方式有静态、横向滚动、垂直滚动和翻页显示等。单块模块控制驱动12块（最多可控制24块）8X8点阵，共16X48点阵（或32X48点阵），是单块MAX7219（或PS7219、HD7279、ZLG7289及8279等类似LED显示驱动模块）的12倍（或24倍）！可采用“级联”的方式组成任意点阵大显示屏。显示效果好，功耗小，且比采用MAX7219电路的成本更低。FifthLEDapplicationsItisasemiconductorlight-emittingdiodebycontrollingthedisplay,whichprobablylooklikethatfromlotsofsmallredlightsareusuallyformedbythebrightlightsofftoshowcharacter.Usedtodisplaytext,graphics,images,animations,quotes,video,videosignalsandotherinformationonthedisplayscreen.GraphicdisplayandLEDdisplayintothevideodisplaybytheLEDmatrixblocks.GraphicdisplayscanbesynchronizedwiththecomputerdisplayChinesecharacters,Englishtextandgraphics;videodisplayusingmicro-computercontrol,graphics,images,andMao,real-time,synchronization,clearmessagetothebroadcastofavarietyofinformationdissemination,butalsoshowstwodimensional,three-dimensionalanimation,video,TV,VCDprogramsandliveon.LEDdisplayshowsthescreenbrightlycolored,three-dimensionalsenseofstrong,static,suchaspainting,movingasthefilmiswidelyusedinfinance,tax,business,telecommunications,sports,advertising,industrialenterprises,transport,educationsystems,stations,docks,airports,shoppingmalls,hospitals,hotels,banks,securitiesmarkets,constructionmarket,auctionhouses,industrialenterprisesinmanagementandotherpublicplaces.LEDdisplaycanshowchangesinthenumbers,text,graphicsandvideo;notonlycanbeusedintheindoorenvironmentcanalsobeusedforoutdoorenvironment,withaprojector,TVwall,LCDscreencannotmatchadvantage.五LED应用范围LED是一种通过控制半导体发光二极管的显示方式，其大概的样子就是由很多个通常是红色的小灯组成，靠灯的亮灭来显示字符。用来显示文字、图形、图像、动画、行情、视频、录像信号等各种信息的显示屏幕。LED显示屏分为图文显示屏和视频显示屏，均由LED矩阵块组成。图文显示屏可与计算机同步显示汉字、英文文本和图形；视频显示屏采用微型计算机进行控制，图文、图像并茂，以实时、同步、清晰的信息传播方式播放各种信息，还可显示二维、三维动画、录像、电视、VCD节目以及现场实况。LED显示屏显示画面色彩鲜艳，立体感强，静如油画，动如电影，广泛应用于金融、税务、工商、邮电、体育、广告、厂矿企业、交通运输、教育系统、车站、码头、机场、商场、医院、宾馆、银行、证券市场、建筑市场、拍卖行、工业企业管理和其它公共场所。LED显示屏可以显示变化的数字、文字、图形图像；不仅可以用于室内环境还可以用于室外环境，具有投影仪、电视墙、液晶显示屏无法比拟的优点。SixthLEDscreentestmethodAlookatScreensize,appearance,smoothness,withthescreenconnectionandsoon

Secondlookafterthedeadpixelscreenlightup,notinnotwithinthescopeof(ingeneralthescreenisbasicallygonenow)

Colorconsistency,displaytextisnormal,displaypictures,playfullscreenfullcolortowhite,red,green,andblue.六LED显示屏检验方法一看屏体规格，外观，平整度，屏内的连线等二看屏点亮后坏点，在不在不范围之内，（一般来说现在的屏基本上没有了）

色差一致性，显示文字是否正常，显示屏图片等，全彩的要全屏打白色，红，绿，蓝。

HowLightEmittingDiodesWorkLightemittingdiodes,commonlycalledLEDs,arerealunsungheroesintheelectronicsworld.Theydodozensofdifferentjobsandarefoundinallkindsofdevices.Amongotherthings,theyformthenumbersondigitalclocks,transmitinformationfromremotecontrols,lightupwatchesandtellyouwhenyourappliancesareturnedon.Collectedtogether,theycanformimagesonajumbotelevisionscreenorilluminateatrafficlight.Basically,LEDsarejusttinylightbulbsthatfiteasilyintoanelectricalcircuit.Butunlikeordinaryincandescentbulbs,theydon'thaveafilamentthatwillburnout,andtheydon'tgetespeciallyhot.Theyareilluminatedsolelybythemovementofelectronsinasemiconductormaterial,andtheylastjustaslongasastandardtransistor.Inthisarticle,we'llexaminethesimpleprinciplesbehindtheseubiquitousblinkers,illuminatingsomecoolprinciplesofelectricityandlightintheprocess.WhatisaDiode?Adiodeisthesimplestsortofsemiconductordevice.Broadlyspeaking,asemiconductorisamaterialwithavaryingabilitytoconductelectricalcurrent.Mostsemiconductorsaremadeofapoorconductorthathashadimpurities(atomsofanothermaterial)addedtoit.Theprocessofaddingimpuritiesiscalleddoping.InthecaseofLEDs,theconductormaterialistypicallyaluminum-gallium-arsenide.Inpurealuminum-gallium-arsenide,alloftheatomsbondperfectlytotheirneighbors,leavingnofreeelectrons(negatively-chargedparticles)toconductelectriccurrent.Indopedmaterial,additionalatomschangethebalance,eitheraddingfreeelectronsorcreatingholeswhereelectronscango.Eitheroftheseadditionsmakethematerialmoreconductive.AsemiconductorwithextraelectronsiscalledN-typematerial,sinceithasextranegatively-chargedparticles.InN-typematerial,freeelectronsmovefromanegatively-chargedareatoapositivelychargedarea.AsemiconductorwithextraholesiscalledP-typematerial,sinceiteffectivelyhasextrapositively-chargedparticles.Electronscanjumpfromholetohole,movingfromanegatively-chargedareatoapositively-chargedarea.Asaresult,theholesthemselvesappeartomovefromapositively-chargedareatoanegatively-chargedarea.AdiodecomprisesasectionofN-typematerialbondedtoasectionofP-typematerial,withelectrodesoneachend.Thisarrangementconductselectricityinonlyonedirection.Whennovoltageisappliedtothediode,electronsfromtheN-typematerialfillholesfromtheP-typematerialalongthejunctionbetweenthelayers,formingadepletionzone.Inadepletionzone,thesemiconductormaterialisreturnedtoitsoriginalinsulatingstate--alloftheholesarefilled,sotherearenofreeelectronsoremptyspacesforelectrons,andchargecan'tflow.Togetridofthedepletionzone,youhavetogetelectronsmovingfromtheN-typeareatotheP-typeareaandholesmovinginthereversedirection.Todothis,youconnecttheN-typesideofthediodetothenegativeendofacircuitandtheP-typesidetothepositiveend.ThefreeelectronsintheN-typematerialarerepelledbythenegativeelectrodeanddrawntothepositiveelectrode.TheholesintheP-typematerialmovetheotherway.Whenthevoltagedifferencebetweentheelectrodesishighenough,theelectronsinthedepletionzoneareboostedoutoftheirholesandbeginmovingfreelyagain.Asaresult,thedepletionzonedisappears.WhenthenegativeendofthecircuitishookeduptotheN-typelayerandthepositiveendishookeduptoP-typelayer,electronsandholesstartmoving.IftheP-typesideisconnectedtothenegativeendofthecircuitandtheN-typesideisconnectedtothepositiveend,currentwillnotflow.Nocurrentflowsacrossthejunctionbecausetheholesandtheelectronsareeachmovinginthewrongdirection.WhenthepositiveendofthecircuitishookeduptotheN-typelayerandthenegativeendishookeduptotheP-typelayer,thedepletionzonegetsbigger.Theinteractionbetweenelectronsandholeshasaninterestingeffect--itgenerateslight!Inthenextsection,we'llfindoutexactlywhythisis.HowCanaDiodeProduceLight?Lightisaformofenergythatcanbereleasedbyanatom.Itismadeupofmanysmallparticle-likepacketsthathaveenergy.Theseparticles,calledphotons,arethemostbasicunitsoflight.Photonsarereleasedasaresultofmovingelectrons.Inanatom,electronsmoveinorbitalsaroundthenucleus.Electronsindifferentorbitalshavedifferentamountsofenergy.Generallyspeaking,electronswithgreaterenergymoveinorbitalsfartherawayfromthenucleus.Foranelectrontojumpfromalowerorbitaltoahigherorbital,somethinghastoboostitsenergylevel.Conversely,anelectronreleasesenergywhenitdropsfromahigherorbitaltoalowerone.Thisenergyisreleasedintheformofaphoton.Agreaterenergydropreleasesahigher-energyphoton,whichischaracterizedbyahigherfrequency.Aswesawinthelastsection,freeelectronsmovingacrossadiodecanfallintoemptyholesfromtheP-typelayer.Thisinvolvesadropfromtheconductionbandtoalowerorbital,sotheelectronsreleaseenergyintheformofphotons.Thishappensinanydiode,butyoucanonlyseethephotonswhenthediodeiscomposedofcertainmaterial.Theatomsinastandardsilicondiode,forexample,arearrangedinsuchawaythattheelectrondropsarelativelyshortdistance.Asaresult,thephoton'sfrequencyissolowthatitisinvisibletothehumaneye--itisintheinfraredportionofthelightspectrum.Thisisn'tnecessarilyabadthing,ofcourse:InfraredLEDsareidealforremotecontrols,amongotherthings.Visiblelight-emittingdiodes(VLEDs),suchastheonesthatlightupnumbersinadigitalclock,aremadeofmaterialscharacterizedbyawidergapbetweentheconductionbandandthelowerorbitals.Thesizeofthegapdeterminesthefrequencyofthephoton--inotherwords,itdeterminesthecolorofthelight.Whilealldiodesreleaselight,mostdon'tdoitveryeffectively.Inanordinarydiode,thesemiconductormaterialitselfendsupalotofthelightenergy.LEDsarespeciallyconstructedtoreleasealargenumberofphotonsoutward.Additionally,theyarehousedinaplasticbulbthatconcentratesthelightinaparticulardirection.LEDshaveseveraladvantagesoverconventionalincandescentlamps.Foronething,theydon'thaveafilamentthatwillburnout,sotheylastmuchlonger.Additionally,theirsmallplasticbulbmakesthemalotmoredurable.Theyalsofitmoreeasilyintomodernelectroniccircuits.Butthemainadvantageisefficiency.Inconventionalincandescentbulbs,thelight-productionprocessinvolvesgeneratingalotofheat.Thisiscompletelywastedenergy,unlessyou'reusingthelampasaheater.LEDsgenerateverylittleheat,relativelyspeaking.Amuchhigherpercentageoftheelectricalpowerisgoingdirectlytogeneratinglight,whichcutsdownontheelectricitydemandsconsiderably.Upuntilrecently,LEDsweretooexpensivetouseformostlightingapplications.Thepriceofsemiconductordeviceshasplummetedoverthepastdecade,however,makingLEDsamorecost-effectivelightingoptionforawiderangeofsituations.Whiletheymaybemoreexpensivethanincandescentlightsupfront,theirlowercostinthelongruncanmakethemabetterbuy.Inthefuture,theywillplayanevenbiggerroleintheworldoftechnology.TRANSIENTVOLTAGESUPPRESSOR(TVS)DiodePRESENTATION•Highprotectiononsensitivemobileelectronicdevices•FollowstrictlytotheIEC61000-4-2ESDteststandard•UsingthebehaviorofdiodeP/NjunctiontoachieveESDprotectionWhatareTransientVoltages?•Thesearefaultswhichcausethevoltagetogooutsidenormallimitsforaperiodoftime.Transientvoltagesarecharacterizedbythreethings:VeryHighVoltage,OccurForAVeryShortPeriodoftime(innanoseconds)andHighOccurrence.Manytransientscausedamagetomicro-semiconductorchipsetsbydegradingtheirperformance.Thisdamageiscumulativeandeventuallyreachesapointwheresuddenandcompletefailureofthecomponentresults.Moreover,sometransientsarecapableofcausingimmediateequipmentfailures.Equipmentfailurescausedbytransientsarehardtodetectandareoftenincorrectlyblamedonother‘perceived’causes.Microsemiconductorchipsetsdamagedbytransientsoftenrequiresophisticatedinstrumenttoreplacethemwhichmakethemexpensivetorepair.Theonlycureistoclamptransientstoasafelevelwheretheprotectedloadcanwithstand.TVSdiode’sAdvantages•TVSDiodevs.ZenerDiodeComparedwiththetraditionalZenerdiode,TVSdiodehasalargerP/Ncrosssection.TVSdiodecomponentisconstructedanddesignedtoabsorblargeramountsofenergy,joules,withafasterresponsetimethanZenerdiode.Zenerdiodehasahigherclampingvoltageandheatdissipationisslower.•TVSDiodevs.MultilayerMetaloxideVaristor,MLVAmajordifferencebetweenTVSdiodeandMLVis,asMLVabsorbstransientenergy,itselectricalparameterssuchasLeakagecurrentandBreakdownvoltagetendtodriftawayfromtheiroriginalspecificationswhichexhibitsaninherentwearoutmechanismwithinthestructure.Becauseofitshighimpedance,itsclampingratiocanreachashighas3.ThereforeMLVismoresuitabletobeappliedonlesssensitivelineswhereitshighclampingvoltagecanbetolerated.•TVSDiodevs.CeramicCapacitorCeramiccapacitorisnotabletowithstandahightransientvoltage.A10kVtransientvoltagewilldestroyabout60%ofthecomponentoftheceramiccapacitorwhileTVSdiodeisabletowithstandupto15Kvtransientvoltage.CeramiccapacitorisalsonotabletodissipateheatefficientlylikewhatTVSdiodedoeswhentransientoccurs.•TVSDiodevs.GasDischargeTubes,GDTsTVSdiodelimitsvoltagespiketoacceptablelevelbyclampingwhileGDTlimitsvoltagespikebycrowbaraction.GDTconductswhenitsthresholdvoltageisexceededandthentriggertoanon-statevoltageofonlyafewvolts.AdrawbackofGDTprotectionisthatthetriggeronstatevoltageisbelowtheoperatingvoltageoftheprotectedload.Theprotectedloadwillbeshutdowntemporarily.LED是如何工作的通常被称为LED的发光二极管，是电子世界中真正的无名英雄。LED的功能多达几十种，被广泛的应用于各种装置之中。在其他应用场合，LED可以作为数字钟的数码显示、传送来自遥控装置的数据、手表的背光灯以及指示各种器械何时开启。归纳起来，LED可以在巨大的电视荧屏上形成各种图像或者点亮交通灯。从本质上讲，LED就是一