Impact PrintersWord下载.docx

Impact PrintersWord下载.docx

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∙Duplication:

Ifcarbonpaperisputintotheprinterthenanimpactprintercanprintmorethanonecopyofadocumentatatime.Thisfeatureisoftenusedbycompanieswhentheyprintinvoices,billsetc.Thecompanycankeeponecopythemselvesandsendtheothercopytothecustomer.

Dot-MatrixPrinters

Thetechnologybehinddot-matrixprintingisquitesimple.Thepaperispressedagainstarubber-coatedcylinderandisintermittentlypulledforwardasprintingprogresses.Theelectromagnetically-drivenprintheadmovesacrossthepaperandstrikestheprinterribbonsituatedbetweenthepaperandprintheadpin.Theimpactoftheprintheadagainsttheprinterribbonimprintsinkdotsonthepaperwhichformhuman-readablecharacters.

Dot-matrixprintersvaryinprintresolutionandoverallqualitywitheither9or24-pinprintheads.Themorepinsperinch,thehighertheprintresolution.Mostdot-matrixprintershaveamaximumresolutionaround240dpi（dotsperinch）.Whilethisresolutionisnotashighasthosepossibleinlaserorinkjetprinters,thereisonedistinctadvantagetodot-matrixoranyformofimpactprinting.Becausetheprintheadmuststrikethesurfaceofthepaperwithenoughforcetotransferinkfromaribbonontothepage,itisidealforenvironmentsthatmustproducecarboncopiesthroughtheuseofspecialmulti-partdocuments.Thesedocumentshavecarbonorotherpressure-sensitivematerialontheundersideandcreateamarkonthesheetunderneathwhenpressureisapplied.Thereforesincepressureisappliedtothepaperbytheprintheadthecarbonpaperwouldthenimprintthesametextonthepaperbehindit,almostorexactlylikeareceipt.

∙Dotmatrixprintersarecheaptopurchaseandhavelowoperatingcosts.

∙Mostcanrunineitherdraftmode（quickbutverylowquality）orNearLetterQualitymode（slowerbutbetterquality）.

∙Thedisadvantagesofdotmatrixprintersarethattheoutputqualityispoor,ittakesalongtimetoprintadocumentandthenoisecanbeannoying.

Howdoesadotmatrixprinterproduceoutput?

∙Producesanimagebystrikingthepaperthrougharibbon.

∙Itsprintheadconsistsofasmallnumberofpinsvaryingbetween9and24.

∙Astheprintheadmovesacrossthepageoneormorepinsstriketheribbonandmakeadotonthepaper.

Daisy-wheelPrinters

ThetechnologicalconceptbehindDaisy-wheelprintersisquitesimilartothatofamanualtypewriter.Theseprintershaveprintheadscomposedofmetallicorplasticwheelscutintopetals.Eachpetalhastheformofaletterincapitalandlower-case,number,orpunctuationmarkonit.Whenthepetalisstruckagainsttheprinterribbon,theresultingshapeforcesinkontothepaper.Daisy-wheelprintersareloudandslow.Theycannotprintgraphics,andcannotchangefontsunlesstheprintwheelisphysicallyreplaced.Withtheadventoflaserprinters,daisy-wheelprintersaregenerallynotusedinmoderncomputingenvironments.Theyhavebecomeobsolete.

HowdoesaDaisywheelprinterproduceoutput?

∙Thecharacterpatternsareallarrangedaroundtheedgeofawheel.

∙Whenaletteristobeprintedthewheelrotatessothatthecorrectletterislinedupwiththeribbon.

∙Thewheelisthenpressedagainsttheribbontoprintthecharacteronthepaper.

Daisywheelprintersareveryslowandnoisy.Itisnotpossibletoprintgraphicsusingadaisywheelprinter.

LinePrinters

Anothertypeofimpactprinter,somewhatsimilartothedaisy-wheel,isthelineprinter.Themaindifferenceisthatinsteadofaprintwheel,lineprintershaveamechanismthatallowsmultiplecharacterstobesimultaneouslyprintedonthesameline.Themechanismmayusealargespinningprintdrumoraloopedprintchain.Asthedrumorchainarerotatedoverthepaper'

ssurface,electromechanicalhammersbehindthepaperpushthepaper（alongwitharibbon）ontothesurfaceofthedrumorchain,markingthepaperwiththeshapeofthecharacteronthedrumorchain.Lineprintersaremuchfasterthandot-matrixordaisy-wheelprinters;

however,theytendtobequiteloud,havelimitedmulti-fontcapability,andoftenproducelowerprintqualitythanmorerecentprintingtechnologies.Sincelineprintersareusedfortheirspeed,theyusespecialtractor-fedpaperwithpre-punchedholesalongeachside.Thisarrangementmakescontinuousunattendedhigh-speedprintingpossible,withstopsonlyrequiredwhenaboxofpaperrunsout.Thistypeofprinterisnotusedwithsmallorpersonalcomputers,butisusedwithlargecomputers.Becauseofitshighspeeditisidealforcompanieswherealotofprintinghastobedone.

Non-ImpactPrinters

Thisreferstoasettypeofprinterswhichoperatewithoutstrikingthepaperortheribbon.Thesetypesofprintersarequieterthantheimpactprinters.TherearetwomaintypesofNon-Impactprinters,laserprintersandinkjetprinters.However,thethermalprinterisalsoconsideredasaNon-Impactprinter.

LaserPrinters

Aphotoconductivedrumisinitiallychargedandthenahighintensitylaserbeamisusedtodischargeselectedareasonthedrum.Thesedischargedareascorrespondtothewhiteareasoftheprinteddocument.Tonerisattractedtopartsofthedrumwithahighcharge.Thedrumrotatesandtransfersthetonertothepaperwhichhasanevengreaterelectricalcharge.Finallyaheaterfixesthetonerontothepaper.LaserPrintersusealaserbeamanddrypowderedinktoproduceafinedotmatrixpattern.Theyproducesharp,crispimagesofbothtextandgraphics,providingresolutionsfrom300dpiupto1200dpi.Theyarequitefast.Theyareusedinbothsmallpersonalcomputersandmainframes.Thestandardofprintisverygoodandlaserprinterscanalsoproduceverygoodqualityprintedgraph.

Laserprintershavebuilt-inRAMchipstostoredocuments

outputfromthecomputer.Ifyouareworkingindesktoppublishingandprintingcomplicateddocumentswithcolorandmanygraphics,youwillneedaprinterwithalotofRAM.LaserprintersalsohavetheirownROMchipstostorefontsandtheirownsmalldedicatedprocessor.

Howdoesalaserprinterproduceoutput?

∙Laserprintersarecalledpageprintersbecausetheyprintawholepageatatime.

∙Alaserbeamisusedtodrawtheimagetobeprintedontoalightsensitivedrum.

∙Aftertheimagehasbeendrawnonthedrum,finepowderinkcalledtonerisputontoit.Thetoneronlystickswherethelaserhasdrawntheimage.

∙Thepaperthenpassesoverthedrumandthetoneristransferredontothepaper.

Laserprintersproduceveryhighqualityoutput,areveryquietandveryfast.Typicalhomelaserprinterscanprint8pagesperminute（ppm）.Someindustrialversionsprintover40ppmandcanprintonbothsidesofapieceofpaperatthesametime.Themaindisadvantageofthistypeofprinteristhehighcost.

InkJet

Likelaseranddot-matrixprinters,ink-jetprintersalsoformimageswithlittledots.Charactersareformedasaresultofelectricallychargedorheatedinkbeingsprayedinfinejetsontothepaper.Individualnozzlesintheprintingheadproducehighresolution（upto400dotsperinchor400dpi）dotmatrixcharacters.Inkjetprintersusecolourcartridgeswhichcombinered,yellowandblueinkstocreatecolourtones.Thismethodofprintingcangenerateupto200cpsandallowsforgoodquality,cheapcolourprinting.

Aninkjetprinter

Colourcartridgeshowinginkjetnozzles

Howdoesaninkjetprinterproduceoutput?

∙Inkisheldincartridges.Colourprintersusuallyuse4cartridges:

Cyan,magenta,yellowandblack.

∙Dropletsofinkareheatedandforcedontothepage

∙Theyformacharacterorshapefrompatternsofdots.（dpi）

Typicallyinkjetprinterscanproduce360or720dotsperinch（dpi）butthesedotsarelargerthanthosethatalaserprintermakessothequalityalthoughverygoodisnotquiteasperfect.Ink-jetprinterscanworkinblackandwhiteorcolour.Blackandwhiteversionscostfrom£

50andcolouronesfromabout£

70.Theyareslowerthanlaserprinters（3ppm+）andcostmoretorun.

ThermalPrinters

Charactersareformedbyheatedelementsbeingplacedincontactwithspecialheatsensitivepaperformingdarkeneddotswhentheelementsreachacriticaltemperature.Thermalprinterpapertendstodarkenovertimeduetoexposuretosunlightandheat.Thestandardofprintproducedispoor.Thermalprintersarewidelyusedinbatterypoweredequipmentsuchasportablecalculatorsandalsousedinprinters.

Howdoesathermalprinterproduceoutput?

∙ThermalprintersarenolongerusedasprintersforPCs.Theyarehoweverstillusedinsomecomputercontrolsystems,tillsandinmanyfaxmachines..Thequalityisreasonableandgraphicscanbeprinted.

∙Theseprintersprintonspecialheatsensitivepaper,whichisexpensive.

∙Theimageisproducedfromsmallblackdots,whicharemadeonthepaperbyheatingitup

Plotter

Aplottercanbeusedtoproduce