Theroleoftheoutputdevice
Theoutputdeviceisageneraltermforthedevicethatsendsinformationfromtheoutsideworldtothecomputerandthedevicethatreturnstheprocessingresulttotheoutsideworld.Thesereturnedresultsmaybevisuallyexperiencedbytheuser,orasinputtootherdevicescontrolledbythecomputer:forarobot,theoutputofthecontrollingcomputerisbasicallytherobotitself,suchasperformingvariousbehaviors..
Thefunctionoftheoutputdevice
Thefunctionoftheoutputdeviceistooutputtheinformationprocessedbythecomputerinthememoryinaformthatcanbeacceptedbypeopleorotherdevices.
Typesofoutputdevices
Therearealsomanytypesofoutputdevices.Commonlyusedoutputdevicesforcomputersincludevariousprinters,perforatedoutputdevices,displaydevices,andplotters.Printersanddisplaydeviceshavebecomenecessaryequipmentforeverycomputerandmostterminals.
Papertapeperforatingoutputmachinepapertapeperforatingoutputdeviceforcomputer.Computeroutputinformationisrepresentedbysmallholesonperforatedpapertape.Thiscannotonlystoreinformationonpapertapeforalongtime,butalsouseperforatedpapertapetoenterthecomputer.
Cardperforatingoutputmachinecomputercardperforatingoutputdevice.Theperforatedcardiseasytoread,canbestoredforalongtime,andcanalsobeusedasacomputerinput.
Classificationofoutputdevices
Display
Display,alsoknownasmonitor,isthemaintoolforman-machinedialogue.Itcandisplaythecommandsordataenteredbythekeyboard,aswellastheresultsofcomputerdataprocessing.
Therearetwomaintypesofcommonlyusedmonitors.OneisCRT(Cath-odeRayTube,cathoderaytube)display,usedingeneraldesktopmicrocomputers;theotherisliquidcrystal(LiquidCrystalDisplay,referredtoasLCD)display,usedinportablemicrocomputers.ThefollowingmainlyintroducesCRTmonitors.Accordingtothecolordistinction,itcanbedividedintomonochrome(blackandwhite)displayandcolordisplay.
Colordisplayisalsocalledgraphicdisplay.Ithastwobasicworkingmodes:charactermodeandgraphicmode.Inthecharactermode,thedisplaycontentisbasedonstandardcharacters.Thefontofthecharacteriscomposedofadotmatrix,andthedotmatrixofthecharacterisstoredinthefontgenerator.Ingraphicsmode,thedisplaycontentisinpixels.Eachpoint(pixel)onthescreencanbecontrolledbytheprogramtocontrolitsbrightnessandcolor,soitcandisplayhigher-qualitygraphicsorimages.
Theresolutionofthemonitorisdividedintothreetypes:high,middleandlow.Theindexofresolutionisexpressedbytheproductofthenumberofpixelsperlineonthescreenandthenumberoflinesperframe(eachscreenpicture).Thelargertheproduct,thesmallerthepixel,themorethenumber,thehighertheresolution,andtheclearerandmorebeautifulthegraphics.
Displayadapter
DisplayTheadapter,alsoknownasthedisplaycontroller,istheinterfacecomponentbetweenthedisplayandthehost,whichisinsertedonthemotherboardintheformofahardwareplug-incard.Theresolutionofthedisplayisnotonlydeterminedbythecathoderaytubeitself,butalsorelatedtothelogiccircuitofthedisplayadapter.Commonlyusedadaptersare:
(1)CGA(ColourGraphicAdapter)colorgraphicsadapter,commonlyknownasCGAcard,issuitableforlow-resolutioncolorandmonochromedisplays.Thedisplaymodesitsupportsare:
Incharactermode,40columns×25rows,80columns×25rows,4colorsor2colors.
Ingraphicsmode,320×200,4colors;640×200,2colors.
(2)EGA(EnhancedGraphicAdapter)enhancedgraphicsadapter,commonlyknownasEGAcard,issuitableformedium-resolutioncolorgraphicsdisplays.Thedisplaymodeitsupportsis:incharactermode,80×25columns,256colors,ingraphicsmode,640×350,16colors
SuperEGAcard,supports800×600,16colors.
(3)VGA(VideoGraphicArray)videographicsarray,commonlyknownasVGAcard,issuitableforhigh-resolutioncolorgraphicsdisplays.Thestandardresolutionis640×480,256colors.MostusedareenhancedVGAcards,suchasSuperVGAcards,withresolutionsof800×600,1024×768,etc.,and256colors.
(4)Chinesedisplayadapter
IntheprocessofdevelopingtheChinesecharactersystem,ChinahasdevelopedsomedisplayadaptersthatsupportChinesecharacters,suchasGW-104card,CEGAcard,CVGAcard,etc.SolvetheproblemoffastdisplayofChinesecharacters.
Printer
Theprinterisanoutputdevicethatprintstheprocessingresultsofthecomputeronpaper.Peopleoftencalltheoutputofthemonitorasoftcopyandtheoutputofaprinterasahardcopy.Adevicethatconvertscomputeroutputdataintoprintedfonts.Fromtheperspectiveofuse,itcanbedividedintotwocategories.Onetypehaskeyboardinputfunction,whichisslower,buthastheabilitytotalktothecomputer.Itisinexpensive,andinadditiontocommonlyusedcomputersandterminals,communicationsystemsalsouseitasconventionalequipment.Theotherhasnokeyboardinputfunction.Thistypeofprintercanbedividedintostripprinters,narrowlineprinters,serialprinters,lineprintersandpageprinters.Accordingtothephysicalstructure,printerscanbedividedintotwotypes:impacttypeandnon-impacttype.
Printerclassification
Accordingtothetransmissionmethod,itcanbedividedintocharacterprintersthatprintonecharacteratatime,lineprintersthatprintonelineatatime,andonepageatatime.Thepageprinter.
Accordingtotheworkorganization,itcanbedividedintoimpactprintersandnon-impactprinters.Theimpacttypeisdividedintowordmodeprinteranddotmatrixprinter.Non-impactprintersaredividedintoinkjetprinters,laserprinters,thermalprintersandelectrostaticprinters.Themostcommonlyusedmicrocomputerisadotmatrixprinter.Dotmatrixdotmatrixprinterfeatures:simplestructure,smallsize,lowprice,unlimitedcharactertypes,lowrequirementsforprintingmedia,andcanprintmulti-layermedia.Structure:printheadandwordcarriage;paperfeedingmechanism;ribbonmechanism;controller:similartothedisplaycontroller.Severalneedlesareinstalledontheprinthead,andthecorrespondingcharactersandgraphicscanbeobtainedbycontrollingdifferentneedlestoprintthepaperthroughtheribbonduringprinting.Therefore,itisoftencalledadotmatrixprinter.Themostcommonlyusedprintersare9-pinor24-pinprinters,mainly24-pinprinters.
Inkjetprintersandlaserprintersarealsowidelyused.Inkjettypeistocontrolthedeflectionofaverythininkthroughthemagneticfield,andcontroltheejectionornon-ejectionoftheinkatthesametime,thenthecorrespondingcharactersorgraphicscanbeobtained.Thelasertypeusestheprincipleofelectrophotography.Acontrolledlaserbeamisdirectedtothesurfaceofthephotosensitivedrum,andtonerofdifferentthicknessesisadsorbedatdifferentpositions,andthecorrespondingcharactersorgraphicsareprintedonthepaperthroughtheeffectoftemperatureandpressure.Itisverysimilartothewayofxerographiccopiers.Thelaserprinterhashighresolution,clearandbeautifulprint,butthepriceishigher.
Inkjetprinter
Aninkjetprinterisaprintersimilartowritingwithink,whichcandirectlysprayinkontoplainpapertoachieveprinting.Realizecolorhardcopyoutput.
Therearetwotypesofinkjettechnologyforinkjetprinters:continuousandrandom.Atpresent,mostofthepopulartypesofprintersonthemarketuserandominkjettechnology.Intheearlyyears,inkjetprintersandcurrentlarge-formatprintersusedcontinuousinkjettechnology.
Theperformanceoflaserprinters
Theprintingresolutionofordinarylaserprinterscanreach300DPI(300dotsperinch)or400DPI,oreven600DPI.EspeciallyforChinesecharactersorgraphics/imageoutput,itisanidealoutputdevice.
Laserprintersarecalled"pageoutputdevices",expressedinpagesperminute(pagesperminute,referredtoasPPM).Thehighspeedisabove100PPM,andthemediumspeedis30~60PPM.Theyaremainlyusedinlargecomputersystems.Thelowspeedis10~20PPM,orevenbelow10PPM,whichismainlyusedinofficeautomationsystemsandtexteditingsystems.
Thermaltransferprinter
Theprintingqualityofthermaltransferprintersisbetterthandotmatrixprinters,whichisequivalenttoinkjetprinters.Theprintingspeedisrelativelyfast,andtheserialtypecangenerallyexceed6Page/minute,theresolutionreaches360DPI.
Printingprinciple
Theprintheadinthethermaltransferprinterisathinfilmheadmadeofsemiconductorintegratedcircuittechnology.Thereisaheatingresistorinthehead.Itismadeofahigh-powerdensityAndhightemperatureresistantfilmmaterials.
Theheat-sensitiveinkiscoatedonthepolyesterbasefilmtoformathermaltransferribbon,whichislocatedbetweenthethermalprintheadandtherecordingpaper.Whenprinting,thepulsesignalheatstheheatingresistorintheprintheadtoseveralBaidu(suchas300℃),andtheprintheadispressedonthepolyesterfilm,sothattheinkonthefilmbaseismeltedandtransferredtotherecordingpapertoleavethecolordots.Colordotsmakeupcharacters,graphicsorimages.
IfyouprintChinesecharacters,youcanprintdirectlytoaprinterequippedwithaChinesecharacterlibrary,andtheprintingspeedisfast.IfthereisnoChinesecharacterlibrary,youneedtoinstalltheChinesecharacterdriverofthiskindofprinterinthecomputer.IftheChinesecharacterlibraryofthecomputerisused,theprintingspeedwillbeslower.
Workingmode
Theprinterhastwoworkingmodes:onlineandoffline.Theso-calledonlineistoconnectwiththehostandbeabletoreceiveandprinttheinformationsentbythehost.Theso-calledofflineistocutofftheconnectionwiththehost.Intheofflinestate,self-checkorautomaticfeeding/unloadingcanbecarriedout.Thesetwostatesarecontrolledbytheonlinebuttonontheprinterpanel.
PrinterController
Theprintercontroller,alsoknownastheprinteradapter,isthecontrolmechanismoftheprinter.Itisalsotheinterfacecomponentbetweentheprinterandthehost,whichisinsertedonthemotherboardintheformofahardwareplug-incard.Thestandardinterfaceisaparallelinterface,whichcantransmitmultipledataatthesametime,whichisfasterthantheserialinterface.
Plotter
Anautomaticplotterisadrawingdevicethatisdirectlycontrolledbyanelectroniccomputerordigitalsignaltoautomaticallyoutputvariousgraphics,imagesandcharacters.Itcanworkonlineoroffline.Itisakindofperipheralequipmentwidelyusedincomputer-aideddrawingandcomputer-aideddesign.Thecommondrawingmethodsaredividedintotrackingplotters(suchaspenplotters)andscanningplotters(suchaselectrostaticscanningplotters,laserscanningplotters,andinkjetscanningplotters).Accordingtothemechanicalstructure,itisdividedintotwocategories:rollertype(drumtype)plottersandflattableplotters.ThetransmissionmethodsofCNCplottersincludesteelwireorsteelbelttransmission;ballscreworrackandpiniontransmission;motortransmission,suchaslinearsteppingmotorswithopen-loopcontrolandservomotorswithclosed-loopcontrol.Plotterisadevicethatcanautomaticallydrawgraphicsaccordingtopeople'srequirements.Itcanoutputtheoutputinformationofthecomputerintheformofgraphics.Mainlycandrawvariousmanagementchartsandstatisticalcharts,geodeticsurveycharts,architecturaldesigndrawings,circuitwiringdiagrams,variousmechanicaldrawingsandcomputer-aideddesigndrawings,etc.ThemostcommonlyusedistheX-Yplotter.Modernplottershaveintelligentfunctions.Ithasamicroprocessor,canusedrawingcommands,hasfunctionssuchasstraightlineandcharactercalculationprocessing,andself-detection.Generally,thiskindofplottercanalsobeequippedwithavarietyofstandardinterfacesforconnectingwiththecomputer.
Aplotterisahardcopydevicethatoutputsgraphics.Theplotterdrawscomplexandaccurategraphicsunderthesupportofdrawingsoftware,whichisanindispensabletoolforallkindsofcomputer-aideddesign.Theperformanceindicatorsoftheplottermainlyincludethenumberofdrawingpens,thesizeofthedrawing,theresolution,theinterfaceformandthedrawinglanguage.Theplotterisgenerallycomposedofadrivemotor,aninterpolator,acontrolcircuit,adrawingtable,apenholder,andamechanicaltransmission.Inadditiontothenecessaryhardwareequipment,theplottermustalsobeequippedwithawealthofdrawingsoftware.Onlythecombinationofsoftwareandhardwarecanrealizeautomaticdrawing.
Therearemanytypesofplotters.Accordingtothestructureandworkingprinciple,theycanbedividedintotwocategories:roller-typeandtabletop:①Drum-typeplotter.WhentheX-directionsteppingmotordrivestherollertorotatethroughthetransmissionmechanism,thesprocketdrivesthedrawingtomove,therebyrealizingtheX-directionmovement.TheY-directionmovementisrealizedbytheY-directionsteppingmotordrivingthepenholder.Thiskindofplotterhasacompactstructureandalargedrawingformat.Butitneedstousespecialdrawingpaperwithchainholesonbothsides.②Platformplotter.Thedrawingplatformisequippedwithabeam,thepenholderisinstalledonthebeam,andthedrawingpaperisfixedontheplatform.TheX-directionsteppingmotordrivesthebeamandthepenholdertomoveintheXdirection;theY-directionsteppingmotordrivesthepenholdertomoveintheYdirectionalongthebeamguide.Thereare3waystofixthedrawingsontheplatform,namelyvacuumadsorption,electrostaticadsorptionandmagneticstripecompression.Theplatformplotterhashighdrawingaccuracy,nospecialrequirementsfordrawingpaper,andiswidelyused.
Developmentprospects
Theoutputdevicesofthefirstgenerationofcomputersareverylimited.Theusualinputdeviceisaperforatedcardreader,whichisusedtoloadinstructionsanddataintothememory;theoutputdeviceusedtostoretheresultsisgenerallyatape.Withtheadvancementofscienceandtechnology,therichnessofinputandoutputdeviceshasincreased.Takeapersonalcomputerasanexample:thekeyboardandmousearethemaintoolsfortheusertodirectlyinputinformationtothecomputer,whilethemonitor,printer,amplifier,andheadsetreturntheprocessingresults.Inaddition,therearemanyinputdevicesthatcanacceptotherdifferenttypesofinformation,suchasdigitalcamerasthatcaninputimages.Amongtheinputandoutputdevices,therearetwotypesthatareworthnoting:Thefirstcategoryissecondarystoragedevices,suchasharddisks,opticaldiscs,orotherslow-speedbuthigh-capacitydevices.Thesecondiscomputernetworkaccessequipment,throughwhichdirectdatatransmissionbetweencomputershasgreatlyincreasedthevalueofcomputers.TheInternethasenabledtensofmillionsofcomputerstotransmitvarioustypesofdatatoeachother.