LED中英文翻譯論文

PAGEword文檔可自由復制編輯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），發(fā)光二極管，是一種固態(tài)的半導體器件，它可以直接把電轉化為光。LED的心臟是一個半導體的晶片，晶片的一端附在一個支架上，一端是負極，另一端連接電源的正極，使整個晶片被環(huán)氧樹脂封裝起來。半導體晶片由兩部分組成，一部分是P型半導體，在它里面空穴占主導地位，另一端是N型半導體，在這邊主要是電子。但這兩種半導體連接起來的時候，它們之間就形成一個“P-N結”。當電流通過導線作用于這個晶片的時候，電子就會被推向P區(qū)，在P區(qū)里電子跟空穴復合，然后就會以光子的形式發(fā)出能量，這就是LED發(fā)光的原理。而光的波長也就是光的顏色，是由形成P-N結的材料決定的。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歷史及發(fā)展現狀50年前人們已經了解半導體材料可產生光線的基本知識，第一個商用二極管產生于1960年。LED是英文lightemittingdiode（發(fā)光二極管）的縮寫，它的基本結構是一塊電致發(fā)光的半導體材料，置于一個有引線的架子上，然后四周用環(huán)氧樹脂密封，即固體封裝，所以能起到保護內部芯線的作用，所以LED的抗震性能好。發(fā)光二極管的核心部分是由P型半導體和N型半導體組成的晶片，在P型半導體和N型半導體之間有一個過渡層，稱為P-N結。在某些半導體材料的PN結中，注入的少數載流子與多數載流子復合時會把多余的能量以光的形式釋放出來，從而把電能直接轉換為光能。PN結施加反向電壓時，少數載流子難以注入，故不發(fā)光。這種利用注入式電致發(fā)光原理制作的二極管叫發(fā)光二極管，通稱LED。當它處于正向工作狀態(tài)時（即兩端加上正向電壓），電流從LED陽極流向陰極時，半導體晶體就發(fā)出從紫外到紅外不同顏色的光線，光的強弱與電流有關。最初LED用作儀器儀表的指示光源，后來各種光色的LED在交通信號燈和大面積顯示屏中得到了廣泛應用，產生了很好的經濟效益和社會效益。以12英寸的紅色交通信號燈為例，在美國本來是采用長壽命、低光效的140瓦白熾燈作為光源，它產生2000流明的白光。經紅色濾光片后，光損失90%，只剩下200流明的紅光。而在新設計的燈中，Lumileds公司采用了18個紅色LED光源，包括電路損失在內，共耗電14瓦，即可產生同樣的光效。汽車信號燈也是LED光源應用的重要領域。對于一般照明而言，人們更需要白色的光源。1998年白光的LED開發(fā)成功。這種LED是將GaN芯片和釔鋁石榴石（YAG）封裝在一起做成。GaN芯片發(fā)藍光（λp=465nm，Wd=30nm），高溫燒結制成的含Ce3+的YAG熒光粉受此藍光激發(fā)后發(fā)出黃色光射，峰值550nm。藍光LED基片安裝在碗形反射腔中，覆蓋以混有YAG的樹脂薄層，約200-500nm。LED基片發(fā)出的藍光部分被熒光粉吸收，另一部分藍光與熒光粉發(fā)出的黃光混合，可以得到得白光?，F在，對于InGaN/YAG白色LED，通過改變YAG熒光粉的化學組成和調節(jié)熒光粉層的厚度，可以獲得色溫3500-10000K的各色白光。這種通過藍光LED得到白光的方法，構造簡單、成本低廉、技術成熟度高，因此運用最多。LED顯示屏的發(fā)展可分為以下幾個階段：第一階段為1990年到1995年，主要是單色和16級雙色圖文屏。用于顯示文字和簡單圖片，主要用在車站、金融證券、銀行、郵局等公共場所，作為公共信息顯示工具。第二階段是1995年到1999年，出現了64級、256級灰度的雙基色視頻屏。視頻控制技術、圖像處理技術、光纖通信技術等的應用將LED顯示屏提升到了一個新的臺階。LED顯示屏控制專用大規(guī)模集成電路芯片也在此時由國內企業(yè)開發(fā)出來并得以應用。第三階段從1999年開始，紅、純綠、純藍LED管大量涌入中國，同時國內企業(yè)進行了深入的研發(fā)工作，使用紅、綠、藍三原色LED生產的全彩色顯示屏被廣泛應用，大量進入體育場館、會展中心、廣場等公共場所，從而將國內的大屏幕帶入全彩時代。隨著LED原材料市場的迅猛發(fā)展，表面貼裝器件從2001年面世，主要用在室內全彩屏，并且以其亮度高、色彩鮮艷、溫度低的特性，可隨意調整的點間距，被不同價位需求者所接受，在短短兩年多時間內，產品銷售額已超過3億元，表面貼裝全彩色LED顯示屏應用市場進入新世紀。為了適應2008年奧運會的“瘦身”計劃，利亞德開發(fā)了表面貼裝雙基色顯示屏，大量用于訓練館和比賽計時計分系統(tǒng)。在奧運場館全彩屏方面，為緊縮投資，全彩屏大部分采用可拆卸方式，奧運期間可作為實況轉播工具，賽事結束后可用于租賃，作為演出、國家政策發(fā)布等公共場合應用工具，通過這種方式可盡快收回成本。就市場而言，中國加入WTO、北京申奧成功等，成為LED顯示屏產業(yè)發(fā)展的新契機。國內LED顯示屏市場保持持續(xù)增長，目前在國內市場上，國產LED顯示屏的市場占有率近95%。國際上LED顯示屏的市場容量預計以每年30%的速度在增長。目前，LED顯示屏的主要制造廠商集中在日本、北美等地，我國LED制造廠商出口的份額在其中微不足道。據不完全統(tǒng)計，世界上目前至少有150家廠商生產全彩屏，其中產品齊全，規(guī)模較大的公司約有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優(yōu)點導體發(fā)光二極管(LED)作為第三代半導體照明光源。這種產品具有很多夢幻般優(yōu)點：(1)光效率高：光譜幾乎全部集中于可見光頻率，效率可以達到80%-90%。而光效差不多的白熾燈可見光效率僅為10%-20%。(2)光線質量高：由于光譜中沒有紫外線和紅外線，故沒有熱量，沒有輻射，屬于典型的綠色照明光源。(3)能耗?。簡误w功率一般在0.05-1w，通過集群方式可以量體裁衣地滿足不同的需要，浪費很少。以其作為光源，在同樣亮度下耗電量僅為普通白熾燈的1/8-10。(4)壽命長：光通量衰減到70%的標準壽命是10萬小時。一個半導體燈正常情況下可以使用50年，即使長命百歲的人，一生最多也就用2只燈。(5)可靠耐用：沒有鎢絲、玻殼等容易損壞的部件，非正常報廢率很小，維護費用極為低廉。(6)應用靈活：體積小，可以平面封裝，易開發(fā)成輕薄短小的產品，做成點、線、面各種形式的具體應用產品。(7)安全：單位工作電壓大致在1.5-5v之間，工作電流在20-70mA之間。(8)綠色環(huán)保：廢棄物可回收，沒有污染，不像熒光燈一樣含有汞成分。(9)響應時間短：適應頻繁開關以及高頻運作的場合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顯示屏的分類

1、按顏色基色可以分為

單基色顯示屏:單一顏色（紅色或綠色）。

雙基色顯示屏：紅和綠雙基色，256級灰度、可以顯示65536種顏色。

全彩色顯示屏：紅、綠、藍三基色，256級灰度的全彩色顯示屏可以顯示一千六百多萬種顏色。

2、按顯示器件分類

LED數碼顯示屏：顯示器件為7段碼數碼管，適于制作時鐘屏、利率屏等，顯示數字的電子顯示屏。

LED點陣圖文顯示屏：顯示器件是由許多均勻排列的發(fā)光二極管組成的點陣顯示模塊，適于播放文字、圖像信息。

LED視頻顯示屏：顯示器件是由許多發(fā)光二極管組成，可以顯示視頻、動畫等各種視頻文件。

3、按使用場合分類

室內顯示屏：發(fā)光點較小，一般Φ3mm--Φ8mm，顯示面積一般幾至十幾平方米。

室外顯示屏：面積一般幾十平方米至幾百平方米，亮度高，可在陽光下工作，具有防風、防雨、防水功能。

4、按發(fā)光點直徑分類

室內屏：Φ3mm、Φ3.75mm、Φ5mm、

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

室外屏發(fā)光的基本單元為發(fā)光筒，發(fā)光筒的原理是將一組紅、綠、藍發(fā)光二極管封在一個塑料筒內共同發(fā)

5、顯示方式有靜態(tài)、橫向滾動、垂直滾動和翻頁顯示等。單塊模塊控制驅動12塊（最多可控制24塊）8X8點陣，共16X48點陣（或32X48點陣），是單塊MAX7219（或PS7219、HD7279、ZLG7289及8279等類似LED顯示驅動模塊）的12倍（或24倍）！可采用“級聯(lián)”的方式組成任意點陣大顯示屏。顯示效果好，功耗小，且比采用MAX7219電路的成本更低。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應用范圍LED是一種通過控制半導體發(fā)光二極管的顯示方式，其大概的樣子就是由很多個通常是紅色的小燈組成，靠燈的亮滅來顯示字符。用來顯示文字、圖形、圖像、動畫、行情、視頻、錄像信號等各種信息的顯示屏幕。LED顯示屏分為圖文顯示屏和視頻顯示屏，均由LED矩陣塊組成。圖文顯示屏可與計算機同步顯示漢字、英文文本和圖形；視頻顯示屏采用微型計算機進行控制，圖文、圖像并茂，以實時、同步、清晰的信息傳播方式播放各種信息，還可顯示二維、三維動畫、錄像、電視、VCD節(jié)目以及現場實況。LED顯示屏顯示畫面色彩鮮艷，立體感強，靜如油畫，動如電影，廣泛應用于金融、稅務、工商、郵電、體育、廣告、廠礦企業(yè)、交通運輸、教育系統(tǒng)、車站、碼頭、機場、商場、醫(yī)院、賓館、銀行、證券市場、建筑市場、拍賣行、工業(yè)企業(yè)管理和其它公共場所。LED顯示屏可以顯示變化的數字、文字、圖形圖像；不僅可以用于室內環(huán)境還可以用于室外環(huán)境，具有投影儀、電視墻、液晶顯示屏無法比擬的優(yōu)點。SixthLEDscreentestmethodAlookatScreensize,appearance,smoothness,withthescreenconnectionandsoon

Secondlookafterthedeadpixelscreenlightup,notinnotwithinthescopeof(ingeneralthescreenisbasicallygonenow)

Colorconsistency,displaytextisnormal,displaypictures,playfullscreenfullcolortowhite,red,green,andblue.六LED顯示屏檢驗方法一看屏體規(guī)格，外觀，平整度，屏內的連線等二看屏點亮后壞點，在不在不范圍之內，（一般來說現在的屏基本上沒有了）

色差一致性，顯示文字是否正常，顯示屏圖片等，全彩的要全屏打白色，紅，綠，藍。

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稱為LED的發(fā)光二極管，是電子世界中真正的無名英雄。LED的功能多達幾十種，被廣泛的應用于各種裝置之中。在其他應用場合，LED可以作為數字鐘的數碼顯示、傳送來自遙控裝置的數據、手表的背光燈以及指示各種器械何時開啟。歸納起來，LED可以在巨大的電視熒屏上形成各種圖像或者點亮交通燈。從本質上講，LED就是一