телевизия

PrinciplesofTV

ThemethodofusingelectricityforTVinstantlytransmitsvisualimagesoftheevent.Similartomovies,televisionusesthevisualresidualeffectofthehumaneyetodisplayaframeofgradualstillimagestoformavisuallymovingimage.ThetransmittingendoftheTVsystemconvertseachminutepartofthesceneintoelectricalsignalsaccordingtobrightnessandchromaticity,andthentransmitstheminsequence.Atthereceivingend,thebrightnessandchromaofeachminutepartaredisplayedaccordingtothecorrespondinggeometricpositiontoreproducetheentireoriginalimage.TheTVsignalscanningsystemandchannelbandwidthofdifferentcountriesarenotexactlythesame.AccordingtotherecommendationsoftheInternationalRadioConsultativeCommittee(CCIR),theLatinalphabetisusedtodistinguishthem.

TVsignal

TheTVsignalissampled,transmittedandreproducedsequentiallyfrompointtosurfacebyscanning.TheTVscanningsystemofdifferentcountriesisdifferent.InChina,itis25framespersecondwith625linesperframe.Eachlineisscannedfromlefttoright,andeachframeisdividedintotwofieldsofoddandevenlinesfromtoptobottombyinterlacingtoreducethefeelingofflicker.Imageinformationistransmittedduringthescanningprocess,whenthescanningelectronbeamreturnsfromtheendofthepreviouslineforwardtothelineback-travelretracelinebeforethestartpointofthenextline,andaftereachfieldisscannedfromtoptobottom,itreturnstotheupperfieldback-travelreturn.Allsweeplinesshouldbeblanked.Duringthelineandfieldblankingperiod,thelineandfieldsynchronizationsignalistransmittedtosynchronizethescanningofreceivingandsending,soastoaccuratelyreproducetheoriginalimage.

TVcamera

TVcamerafocusesthelightimageofthesceneonthephotosensitive(orlightguide)targetsurfaceofthecameratube,andthephotoelectronexcitationorphotoconductivityateachpointofthetargetsurfaceThechangesvarywiththebrightnessofeachpointofthelightimage.Whenanelectronbeamisusedtoscanthetargetsurface,anelectricalsignalwhoseamplitudeisproportionaltothebrightnessofthelightimageofthesceneateachpointisgeneratedandtransmittedtotheTVreceivertomakethescanningelectronbeamofthekinescopescreenchangewiththestrengthoftheinputsignal.Whenscanningsynchronouslywiththesendingend,theoriginalimagesentwillappearonthescreenofthepicturetube.

TheprocessofTVsignaltransmissionanddistributiontakeslivebroadcastsinothercitiesasanexample,generallyfromcameras,TVcentersorOBtrucks,throughmicrowaverelaylines,transmitterstations,andfinallytouserTVreceivers.Inaddition,televisionbroadcastingsatellitesandcabletelevisionarealsoeffectivemeansfornationalandurbanregionaltelevisiontransmissionanddistribution,respectively.

TVsystem

TheTVsignalscanningsystemofvariouscountriesisnotexactlythesameasthechannelbandwidth.AccordingtotherecommendationsoftheInternationalRadioConsultativeCommittee(CCIR),theLatinalphabetisusedtodistinguish.Forexample,Mrepresents30framespersecond,526linesperframe,andthevideobandwidthis4.2MHz,plusthetotalhighfrequencybandwidthoftheresiduallowersidebandofFMaudioandAMvideois6MHz;DandKrepresent25framespersecond,625perframeOK,thevideobandwidthis6MHz,andthehighfrequencybandwidthis8MHz.ThefullTVsignalofthevideobasebandandtheaudiosignalarerespectivelymodulatedtotheVHForUHFfrequencybandforbroadcasttransmission.

Inadditiontoincludingthescansandchannelsthatarethesameasthoseofblack-and-whiteTV,whicharedistinguishedbyLatinletters,differentcolorTVsystemsareformedaccordingtothedifferentencodinganddecodingmethodsofthethreeprimarycolorsignalsatthetransmittingandreceivingends..Thebroadcastcolortelevisionsystemrequirescompatibilitywithblack-and-whiteTV,thatis,black-and-whiteTVsetscanreceivecolorTVbroadcasts,andcolorTVscanalsoreceiveblack-and-whiteTVbroadcasts,butalltheyreceiveareblack-and-whiteimagesandaccompanyingaudio.Tothisend,colorTVsarebasedontheprincipleofmixingacertainproportionofthethreeprimarycolorsintheadditivecolormixingmethodintovariouscolorsincludingwhitelight.Atthesametime,inordertobecompatibleandcompressthetransmissionband,red(R)andgreen(G)aregenerallyused.Thethreeprimarycolorsignalsofblue(B)andblue(B)composethebrightnesssignal(Y)andthetwocolordifferencesignals(BY)and(RY)ofblueandred.Thebrightnesssignalcanbeusedtotransmitblackandwhiteimages,andthecombinationofthecolordifferencesignalandthebrightnesssignalcanrestoreThreeprimarycolorsignalsofred,greenandblue.Therefore,compatiblecolorTVsnotonlytransmitthesamebrightnesssignalandaudiosignalasblack-and-whiteTVs,butalsotransmitchrominancesignalsatthesametimeinthesamevideofrequencyband.Thechrominancesignaliscomposedoftwocolordifferencesignalsmodulatingthecolorsubcarriersatthehighfrequencyendofthevideofrequencyband.Inordertopreventthemodulationofthecolordifferencesignalfrombeingoverloaded,theblueandreddifferencesignals(BY)and(RY)arecompressedandcompressed.ThefollowingblueandreddifferencesignalsarerepresentedbyUandV.

1. NTSCisacompatiblecolortelevisionsystemofficiallybroadcastintheUnitedStatesin1954,andisalsousedinCanada,Japanandothercountries.NTSCistheabbreviationofNationalTelevisionSystemCommittee(NationalTelevisionSystemCommittee).Thissystemisbasedonthehumaneye’sweakestabilitytodistinguishcolordetailsbetweenblueandmagenta,andthestrongestabilitytodistinguishcolordetailsbetweenredandyellow.ItusesthecolordifferencesignalQandredbetweenblueandmagenta.ThecolordifferencesignalIbetween,andyellowreplacestheblueandreddifferencesignalsUandV.UseQandIcolordifferencesignalstoperformquadraturebalanceamplitudemodulationontwoco-frequencycolorsub-carrierswithinitialphaseanglesof33°and123°tofacilitatedecoding,separationandsuppressionofsub-carriers.Themodulatedtwocolor-differencesignalsaremixedtoformChrominancesignal.Inordertoperformsynchronousdetectiononthechrominancesignalatthereceivingend,itisnecessarytousethehorizontalblankingperiodatthetransmittingendtosendanexcellentsynchronizationsignal.Thissystemischaracterizedbysimpledecodingcircuitandlowcost.

2. Системата PAL е разработена от Федералната република на Германия през 1963 г., за да намали чувствителността на фазите на системата NTSC. Тя е официално излъчена през 1967 г. и не се използва в страни като Обединеното кралство и Китай. PAL е съкращението на линията за редуване на фазите. формира квадратурна балансна амплитудна модулация върху два ко-честотни цветни подносещи с начални фази от 0° и 90° и обръща сигнала за цветова разлика на компонента V по линия. По този начин фазовото отклонение на сигнала на цветността се спестява между съседните централни редове, за да бъде отменено. причинени от появата на призрачни цветове, дължащи се на многопътно приемане по време на предаване.

3. Системата SECAM е официално излъчена във Франция през 1967 г. Тя също е съвместима система за цветна телевизия, разработена за подобряване на чувствителността на фазите на системата NTSC. Използва се и в Съветския съюз и някои източноевропейски страни. ouleuràMémoire).Когато сигналите за яркост и цветност се предават по едно и също време, изпращачът предава сигнали за червена и синя разлика ред по ред. Въпреки това, когато се декодира в края на получаването, е необходимо както сигналът за разлика, така и яркостта, и червеният, и синият сигнал за разлика да се съхраняват, зелени и сини основни цветни сигнали. Следователно линията за забавяне се използва там при получаване декодер, за да съхрани един от получените сигнали за цветова разлика за една линия., И след това с получена яркост на следващия ред (който е бил забавен от една линия при изпращача) и друг сигнал за цветова разлика, за да формира три сигнала за декодиране. ubносители с определен честотен интервал. .

4. Пълен ТВ сигналСъставният сигнал на изображението на предаване в базовата лента на ТВ видео. Пълният ТВ сигнал на черно-бял ТВ включва: синхронизация на линейно (хоризонтално) и поле (вертикално) сканиране и сигнали за заглушаване по време на периода на сканиране назад и черно-бял сигнал за яркост по време на сканиране на време на пътуване напред. Сред тях ,сигналът за синхронизация синхронизира сканирането на получаването и изпращането, за да се гарантира стабилно възпроизвеждане на полученото изображение;сигналът за заглушаване, използван за елиминиране на смущенията на обратната светла линия;сигналът за яркост на черно-бяло, използван за черно-бял или цветен телевизор за получаване на черно-бял телевизионен образ.

Етимология

През 1934 г. Sun Mingjing работи като асистент на YangJianchu в Научното училище, Централния университет в Нанкин, и разработи първия в Китай прототип на принципа на приемане и излъчване на предаване с камера. YangJianchu идентифицира „телевизия“ като съответстваща име на телевизията на китайски.

През 1939 г. Sun Mingjing официално посочи "TV" като тринадесетия курс на университета Jinling, а "TV" официално стана курс на китайския университет.

Systemstructure

Signalsystem

TheTVsignalsystemincludesthreeparts:thepublicsignalchannel,thesoundchannelandthefinalstagecircuitofthevideoamplifier.TheirmainfunctionsareAmplifyandprocessthereceivedhigh-frequencytelevisionsignal(includingimagesignalandaudiosignal),andfinallyreproducetheimageonthefluorescentscreen,andrestoretheaudiointhespeaker.Itiscomposedofhigh-frequencyamplifier,mixerandlocaloscillator.

Thefunctionofthehigh-frequencyamplifieristoselectandamplifythehigh-frequencyTVprogramsignalreceivedbythehigh-ratedtuner,andobtaintheimagemiddle-frequencysignalandtheaudiointermediate-frequencysignalthroughthemixingprocess.

Theroleoftheacousticsurfaceoftheintermediatefrequency(firstintermediatefrequency)signalistoformtheamplitude-frequencycharacteristicsoftheimage.

Ролята на предусилвателя: усилване на малкия сигнал (20 dB усилване като малка стойност), за да компенсира загубата на сигнала от повърхностния акустичен филтър.

Thesurfacefilterrealizestheimpedancematchingbetweenthehigh-pricedtunerandtheimageamplifier.

ACC(automaticgaincontrol)circuit:Bycontrollingthegainofthemid-ampandhigh-amplificationcircuits,theamplitudeofthevideosignalvoltageoftheAGCandANCoutputbythedetectorisbasicallystable;

ANC(Automaticnoisesuppression)circuit:toreducetheinfluenceandinterferenceoftheexternalnoisesignaloftheTVontheTV.

Scanningsystem

TheTVscanningsystemincludesasynchronizationcircuit,alinescanningcircuit,afieldscanningcircuit,apicturetubeanditspowersupplycircuit.Themainfunctionofthescanningsystemistoformanormalgratingonthephosphorscreenofthepicturetube.

TheamplitudeseparationcircuittakesadvantageofthehighestamplitudeofthesyncsignalinallTVsignals,takesoutthecompositesyncsignalandtheintegrationcircuitusesthefeaturethatthewidthoftheverticalsyncsignalismuchsmallerthanthewidthofthehorizontalsyncsignaltosynchronizetheverticalThesignalisseparatedfromthecompositesynchronizationsignaltocontrolthefieldscanningcircuittoachieveTVfieldscanningsynchronization.

TheseparationmethodoftheintegralcircuitisalsocalledthewidthseparationAFCcircuit.ThefunctionoftheAFCcircuitistoautomaticallyrealizethelinesynchronization.Theprincipleistotakethehorizontalsynchronizationsignaloutofthecompositesynchronizationsignal,compareitwiththehorizontalfrequencysawtoothplatingsignalfedbackfromthelineoutputstageofthemachine,andthenoutputtheerrorcontrolvoltagetoadjustthefrequencyandphaseofthehorizontalscanningtorealizethehorizontalTVsynchronizationcircuit.

Захранваща верига

Функцията на захранващата верига на телевизора е да трансформира (понижава) напрежението от 220 VAC, осигурено от телевизора, и след това да го коригира, филтрира и стабилизира, за да отговаря на изискванията. Стабилното постоянно напрежение се подава към всяка част от веригата.

История на развитието

Процес на раждане

Коледа 1883 г.

TheGermanelectricalengineerNipkovusedhisinvented"NipThe"KoffDisk"usedamechanicalscanningmethodtoconductthefirstexperimentoftransmittingimages.Eachpicturehas24lines,andtheimageisquiteblurry.

През 1908г

KembelSwinton,EnglandandRoschenkofffromRussiaputforwardtheprincipleofelectronicscanning,whichlaidthetheoreticalfoundationfortelevisiontechnology.

1923 г

Oneoftheinventorsoftelevision,theSoviet-AmericanZwarikin(alsotranslatedasVeratimirSforodin)inventedtheelectrostaticstoragecameratube.In1923,inventedtheelectronicscanningpicturetube,whichwasthepioneeroftelevisionphotography.

През 1925г

BritishJohnRockyBairdcarriedoutnewresearchworkbasedonthe"NipkovDisc"andinventedamechanicalscanningTVcameraandreceiver.Atthattime,theresolutionofthepicturewasonly30lines,thescannercouldonlyscanthescanningarea5timespersecond,andthepictureitselfwasonly2incheshighandoneinchwide.PerformedtothepublicinasmallshopinLondon.

През 1926г

Oneoftheinventorsoftelevision,Baird,gaveabroadcastandreceptionperformancetotheBritishpress.

1927—1929

BairdconductedthefirstelectromechanicalTVtrialbroadcastviatelephonecable;thefirstshortwaveTVtrial;theBritishBroadcastingCorporationbegantobroadcastTVprogramscontinuouslyforalongtime.

1930 г

RealizethesimultaneousbroadcastingofTVimagesandsound.

1931 г

ThefilmwasputontheTVscreenforthefirsttime.PeoplewatchedthelivebroadcastofthefamousBritishlocaljockeyclubontelevisioninLondon.AmericanFerroFarnsworth,oneoftheinventorsoftelevision,inventedatubetelevisiondevicethatcanproject25imagespersecond.

През 1936г

TheBritishBroadcastingCorporationadoptedBaird'selectromechanicaltelevisionbroadcasting,andforthefirsttimebroadcastedtelevisionimageswithhighdefinitionandenteredthepracticalstage.

През 1939г

American RadioCorporation започна да излъчва изцяло електронна телевизия. Швейцарски Филип изобрети първия черно-бял телевизионен проектор.

1940 г

U.S.Guermadevelopedanelectromechanicalcolortelevisionsystem.

17 декември 1949 г

ThefirsttelevisioncablelaidbetweenLondonandSudenCalfelterwasputintouse.

1951 г

Американецът Х. Лоу изобрети цветна тръба с маска с три сенки, а Лоренцин изобрети цветна тръба с един изстрел.

През 1954г

TheTexasInstrumentsCorporationoftheUnitedStatesdevelopedthefirstall-transistortelevisionreceiver.

1966 г

AmericanRadioCorporationdevelopedintegratedcircuittelevisions.Threeyearslater,acolortelevisionreceiverwithanelectronictuningdevicewasproduced.

През 1972 г

Разработен от Япония цветен телевизионен проектор.

1973 г

Digitaltechnologywasusedintelevisionbroadcasting,andexperimentsprovedthatdigitaltelevisioncanbeusedforsatellitecommunications.

1976 г

Обединеното кралство завърши проучването на системата "TV Library". Потребителите могат директно да проверяват новини, книги, вестници или списания на телевизора.

1977 г

ThefirstbatchofportableTVsetsweredevelopedintheUK.

1979 г

Theworld'sfirst"cableTV"wasopenedinLondon.ItwasinventedbytheBritishPostOffice.Itcantransmittheinformationinthecomputerthroughtheordinarytelephonelineanddisplayitontheuser'sTVscreen.

През 1981г

Японската корпорация Sony разработи джобен черно-бял телевизор с 2,5-инчов LCD екран и захранван от батерия.

През 1984г

Japan'sPanasonicCorporationlaunched"UniversalTV."Thesystem’spictureis3.6meterswideand4.62metershigh,whichisequivalentto210inches.Itcanbeplacedonasmalltruckandplayedinsmallstreetsandsquareswhereneeded.Thesystemusesthe"high-brightnesscolorluminoustube"exclusivelydevelopedbyPanasonic,whichcangetcolorfulandbrightimagesoutdoorseveninthedaytime.

17 март 1985 г

AttheTsukubaScienceWorldExpoheldinJapan,theultra-smallcolorTVwallbuiltbySonywasunveiled.Itislocatedonthecentralsquare,40meterslong,25metershigh,withanareaof​​1,000squaremeters,andtheentirebuildingisashighasa14-storybuilding.Itisquitea1857-inchcolorTV.Theultra-smallscreenconsistsof36smallluminousscreens,eachweighing1tonand1.8metersthick,with4linesand9workstotaling450,000colorluminouselements.Throughthecamerainstalledonthetop,variousactivitiesonthevenuecanbedisplayedatanytime,andvariousadvertisingvideosofSonycanbeplayed.

1985 г

BritishTelecom(BT) стартира интегрирана цифрова комуникационна мрежа. Тя предоставя на потребителите глас, диаграма за бързо предаване, факс, терминал за бавно сканиране и скоро. 25 ноември 1991 г.

Japan’sSonyCorporation’shigh-definitionTVbegantrialbroadcasting:itsscanninglineswere1,125,andtheimagequalitywasimprovedby100%;theaspectratioofthescreenwaschangedfromthetraditional9:12to9:16.Theviewer’ssenseofpresenceisenhanced;theviewingangleoftheflatcamerahasbeenexpandedfrom10degreesto30degrees,andthemaphasamoresenseofdepth;the“pixels”oftheTVsurfaceimagehaveincreasedfrom280,000to1.27millionunitsofinformationinonefellswoopIncreasedbynearly4times...Therefore,thedistancetowatchhigh-definitionTVisnot7timesofthepreviousscreenheightbut3times,andtheaccompanyingsoundisrealistic,using4-channelhigh-fidelitystereo,whichisfullofappeal.

1995 г

Japan’sSonyCorporationlaunchedanultra-miniaturecolorTVreceiver(ie,palm-typecolorTV),whichisassmallasapalmandweighs280grams.Ithasaspeakerandaheadphonejack.TheLCDscreenisabout5.5cm.Thepicturelookssmall,buttheimageisclear.Itsmostobviousfeatureis:thehumanbodyisusedasanantennatoobtaintheviewingeffect,andthetwoleadsareusedwhenwatchingTV.Putitaroundyourneck,youcangettheeffectofanoutdoorantenna.

1996 г

Японската компания Sony представи на пазара "стенния" телевизор: дължината му е 60 см, ширината 38 см, дебелината му е само 3,7 см, а теглото му е само 1,7 кг, точно като една стена.

Развитие на Китай

2 септември 1958 г

първият телевизор в моята страна беше успешно произведен и черно-бялата телевизия започна да се излъчва и съответните телевизори бяха установени в индустрията.

През 1973 г. цветната телевизия е пилотирана.

На 10 август 2019 г. Huawei пусна Honor SmartScreen.

Patentapplication

Bairdapplication

Withtheinventionofthetelephonein1875andthedevelopmentofradioandfilmtechnology,manyscientificandtechnicalpersonnelbegantostudyimagetransmissiontechnology,thinkingApplyingthelatestscientificandtechnologicalachievements,photoelectricconversionofstillormovingscenesandimagesiscarriedout,andelectricalsignalsaresentoutsothatthepicturescanbereproducedinotherplacesinrealtime.TheBritishengineerJ.L.Baird(JohnLogieBaird)whofirstinventedandrealizedsuchaTVsystem.BairdappliedtotheBritishPatentOfficeforthetitle"Systemfortransmittingimages,portraitsandscenesthroughwiredorradiowavecommunication"onJuly26,1923,andwasauthorizedonOctober9,1924.ThepatentnumberisGB222604..Thesystemisnotsomuchelectronicasitismechanical.ItisbasedonPaulNiphow,aRussian-GermanfromBerlin,Germany.TheGermanpatentDE30105named"ElectronicTelescope"in1884,the"ElectronicTelescope"consistsoftwoidenticalrotatingdisks,oneonthetransmitterandtheotheronthereceiver.Eachdiskhas24squareholesandaphotoelectrictubeforimagetransmission.Itisbasedontheconceptofmovingimages,thatis,whenaseriesofstillimageschangefastenough,itwillproducetheeffectofmovingpicturesvisually.However,duetotechnicalreasons,thepatenthasnotbeenimplemented.

Theabove-mentionedBairdpatentsuggestsamethodandsystemfortransmittingimages,portraitsandscenes.Eachareaof​​thesceneissuccessivelyprojectedonthephotosensitiveelement,andthereceiverusesthecurrentcausedbythephotosensitiveelement.Thechangelightsupaseriesofsmalllightssettothescreen,andthechangingilluminanceofthesesmalllightsonthescreenformsareproductionoftheoriginalpicture.Theinventionwillbefurtherdescribedbelowwithreferencetothedrawingsandembodiments:thesceneortargetAtobetransmittedisfocusedonarotatingdiskDthroughalensBtoformanimageC,andthediskDispiercedwithaseriesofsmallholesarrangedinaspiralline.ImageCcanbe1inchx1inch,andthediameteroftheholeonthediskcanbe1/18inch(or1/32inch).Theseholesaredistributedabout1inchcircumferentially.Thesecondholeis1/18inch(or1/32inch)closertothecenterthanthefirsthole,andthethirdholeis1/18inchclosertothecenterthanthesecondhole.Inch(or1/32inch),andsoonuntilthe18thhole(or32ndhole),sothatwhenthediskDrotates,eachpartofthepicturetobeconveyedpassesthrougha1/18inchoneafteranother.Inchholes(or1/32inchholes).ThereisaphotosensitiveelementEatthebackofthedisc.DifferentlightisappliedtothephotosensitiveelementthroughtheperforationM,whichcausesachangeinthecurrentflowingfromthebatteryFthroughthephotosensitiveelement,andthechangingcurrentisreducedthroughathermionicvacuumtube,etc.,throughawireorThecomponentsaretransportedtothereceiver.ThereceiverisequippedwithanarmGthatrotatesincompletesynchronizationwiththediskDofthetransmitter.TheendofthearmhasabrushandcommunicateswithaseriesofcontactsH,andeachcontactisconnectedtoasmalllight.,AndtheselightsarearrangedinrowsandcolumnstoformascreenK.Eachholescansastripofthepicture,andthestripisreproducedbyacolumnoflightsonthereceivingscreen,sothateachholehasitscorrespondingcolumnoflightscorrespondingtoit.Manylightscanbeused,andthemorelightsthebetterthepicture.Ifthecorrespondingmomentaryholefacesthebrightpartofthepicture,thelightwillbeverybright;ifthemomentaryholefacestheblackpartofthepicture,thelightwillbedim;thedifferentbrightnessofthelightonthescreenreproducesthepicture,thusforminganimage.

Bairdwasbornin1888.HestudiedatLatchfieldHighSchool,RoyalCollegeofTechnologyandGlasgowElementarySchool,butdroppedoutofschoolduetotheoutbreakoftheFirstWorldWar.Hewasanunsuccessfulbusinessman.Whenhestartedhisresearchwork,hewasverypoorandhadnofunds.Hehadtousewasteitemssuchasteaboxes,biscuitboxes,wires,wax,etc.,tomakeexperimentaldevicesbyhimself.Eventherotatingdiscsweremadeofcards.Madeofcardboard,thepictureis30linesfromthetoptothebottom,anditistransmitted10timespersecond.

In1924,hesuccessfullylaunchedasmallpictureoftheMalteseCrosswithinafewmeters.OnOctober2,1925,hefinallysucceededinmakingthefaceoftheyoungworkerWilliamTaynton(WillianTaynton)appearonthetelevision.Hesignedacontractwithadepartmentstoreforremunerationfortelevisiontransmissionperformance,andcontinuedtoimprovethesystem.

In1928,Bairdbegantoofficiallybroadcastitstelevisionsystem,andbegantoresearchandexperimentwithcolortelevision.

In1929,theBritishBroadcastingCorporation(BBC)signedalicensecontractwithBairdtousehisinventiontobroadcasttelevisiononatrialbasis.

In1936,theBBCusedradiotorealizetimedtelevisionbroadcastingforthefirsttimeintheworld.However,Baird'sTVadoptsthelimitationsofthemechanicaltechnicalroute.Despitehissmallefforts,thequalityofthetransmittedimageshasalwaysbeenproblematic.Thescanningaccuracyislimitedbytherotationspeed,theimageclarityisnotenough,andtheflickeringimagescauseheadachesfortheaudience.Itwasveryactiveinthisfieldatthattime.WhenBairdwasengagedintheresearchofTVsystemsbasedontheprincipleofmechanicalscanning,Americaninventorswereconductingresearchonelectronicscanning,tryingtoadoptanothertechnologicalroute—electronicTVsystems.

Zwolkin

Russian-AmericanengineerVladimirK.Zwolkin(VladimirEworykin)JappliedforonDecember29,1923,onDecember1938TheUS2141059patent,whichwasapprovedandpublishedonlyonthe20th,inventedtheCRTandcameratubetechnologyandtheTVsystem,layingthefoundationfortheelectronicTVsystem.AlthoughtheelectronicTVsystemwasnotperfectatthebeginning,theeffectwasnotasgoodasthemechanicalone,but,ThankstotheeffortsofZwolkin,AmericanWirelessCompanyandBritishEMICompany,thetechnologyhasmaderapidprogress.Forexample,thescanninglinewas48linesin1929and343linesin1935.

AlthoughZvolkin'spicturetubemakesTVpractical,itcannotmakeTVbroadcasteasyorperfect."Photoelectriccameratube"-asitisoftenmentionedbyTVcrews-canproduceclear,clearimages,butisnotverysensitivetolight.Inbrightdaylight,everythingisnormal,butinastudio,ahugeamountoflightisneeded—morethantheamountoflightrequiredbythefilmindustry.Theheatlevelexceeds100degreesFahrenheit,andactorsandactressesneedmakeup(includingthickeyeshadowboxesandlipgloss)tooffsetthedazzlinglightemittedbytheoldarclamps.Zvolkinandhisteamhavetoremedythis!

Attheendof1936andearly1937,twosystems,EMI’selectronictelevisionsystemandBaird’smechanicaltelevisionsystem,weresetupinAlexandraPalaceinthenorthofLondon,England.Useitinturntocomparewhichofthetwosystemsisbetter.Thefirst-classelectronicvarietytechnology.Threemonthslater,theBBCtoldBairdtoshutdownhissystem.Theelectronictelevisionsystemhasbecomethemainstreamtelevisionsystem.BairddiedinSussex,Englandin1946.Bexhill(Sussex).

Controversialevent

TVisnotaninventionofanyone.Itistheresultofasmallgroupofpeopleindifferenthistoricalperiodsandcountries.Asearlyasthenineteenthcentury,peoplebegantodiscussandexploremethodsoftransformingimagesintoelectronicsignals.In1900,theterm"Television"hadalreadyappeared.

Peopleusuallyregardtheimageofthepuppets"scanned"inanexperimentconductedbytheScotsmanJohnLogieBairdinLondononOctober2,1925asasignofthebirthoftelevision.,Heisknownasthe"fatheroftelevision."However,thisviewiscontroversial.

Because,alsointhatyear,theAmericanVladimirZworykinshowedhisTVsystemtohisbossatWestinghouse.

Althoughthetimeisthesame,thetelevisionsystemsofJohnLogieBairdandVladimirZworykinareslightlydifferent.Historically,thetelevisionsystemofJohnLogieBaird(JohnLogieBaird)wascalledamechanicaltelevision,whiletheSforogen'ssystemwascalledanelectronictelevision.Thisdifferenceismainlyduetothedifferentprinciplesoftransmissionandreception.

Thedevelopmentoftelevisioniscomplicated.Manypeopleweredoingthesameresearchatalmostthesametime.

AmericanRCAlaunchedblackandwhitetelevisionsin1939,setthenationalcolortelevisionstandardin1953andlaunchedRCAcolortelevisionsin1954.

Класификация

От ефекта на използване и външния вид, той може да бъде грубо разделен на 5 категории: телевизор с плосък екран (плазма, LCD и някои ултратънкостенни монтирани DL предварителна проекция), CRTpicturetubeTV (чист плосък CRT, ултраплосък CRT, ултратънък CRT и т.н.), телевизор със задна проекция (CRTзадна проекция, DLPrearпроекция,LCOSреарпроекция, LCD задна проекция), прожекционна телевизия, 3DTV.

Предложение

Колкото по-близо е човекът до телевизора, толкова по-малко е дразненето му, толкова по-вероятно е да причини умора на очите. Следователно поставянето на телевизора трябва да се основава на принципа на адаптиране към физиологичните изисквания на окото.

Thebestpositionisthatthepersonis2.5-8metersawayfromtheTV,anditsheightisslightlylowerthantheeyelevel.Whentheheightistoohigh,itiseasytocausefatiguewhenyoulookup.Whenitistoolow,itiseasytofatiguebecauseyouneedtolookdown.Ofcourse,youshouldalsopayattentionnottoplacetheTVtooobliquely,otherwise,tiltingyourheadwillnotonlycausetheimagetobeunclear,butalsomorelikelytocauseeyefatigue.

WhenwatchingTV,youshouldtakeashortbreakfornomorethan60minutesatatime,preferablywithyoureyesclosed.Someonehasdoneasurvey,ifyouwatchTVformorethan4hourswithouttakingabreak,youcanlosetwolinesofvision(0.2).WatchingTVforalongtimeisnotonlyeasytomakethechild'sbodyweakandobese,butalsoeasytoformmyopia.Ifthechildisalreadysufferingfrommyopia,itisbestnottowatchTVformorethanhalfanhouratatime,andrestfor10minutes.

Inaddition,theroomshouldmaintainacertainbrightnesswhenwatchingTV.Thatistosay,thecontrastbetweenthebrightnessoftheTVandthebrightnessoftheroomaroundtheroomshouldnotbeverydifferent,otherwiseitwilleasilycauseeyefatigue,andwillalsopromotetheformationanddevelopmentofmyopia.Therefore,alow-intensitylampshouldbekeptindoors,anditsbrightnessshouldbesuitabletobeabletoreadthewritingofthebook.

Свързан

Размер на екрана

Размерът на екрана на телевизора е параметър, който измерва най-малкия възможен екран на телевизора. Измерва се по диагонала на екрана на телевизора.

,theunitisusuallyinches.

ThesizeoftheLCDTVscreenisthesizemarkedinthestrictproductmanual,becausetheLCDscreenisnotcoveredbytheframe.

Individualproductssoldinthemarkethavefalsedimensions,whicharemainlymanifestedas1-2cmlessthanthemarkedstandardsize,thatis,lessthan1inchofdistance.

Internetinteraction

TVisareal-timemedia,unlessitisrecorded,itcannotbereviewedorwatchedrepeatedly.However,thenetworkmediahasobviousadvantagesinthisregard.IthasprintmediathatcanbeviewedatanytimeIthasovercometheshortcomingsofpoortimeliness,lackofclassificationandlimitedspace,andhasbecomeafleetingdatabaseofTVprogramsandaclassifiedinformationlibrary.

InteractionisanimportantmeansthatTVmediahasbeenexploringtostrengthentheconnectionbetweenthespreaderandtheaudienceandunderstandtheaudience’sresponse.Thedevelopmentofnetworktechnologyhasallowedpeopletohaveadeeperunderstandingofthewordinteraction,andithasbeenwrittenintothelifeoftheaudienceandthemedia.ThecombinationofTVandtheInternetisthebestmarriage.ThenetworkabsorbsthecontentofTV,andTVusesthenetworkplatformtotrulyoptimizethetransmissioneffect.

SetTopBox

За SetTopBox(SetTopBox),няма стандартна дефиниция.Най-общо казано,всяко мрежово терминално устройство,свързано към телевизор,може да се нарече settopbox.От добавки към аналогови канали и декодери за аналогови канали, базирани на мрежи за кабелна телевизия в миналото, до "Вили"Интернет топбокси, които свързват телефон линии с телевизори и интегрирани декодери на приемници (IRD) за цифрови сателити (IRD), цифрови наземни декодери и цифрови цифрови декодери за кабелна телевизия могат да се наричат ​​декодери. В тесен смисъл ,ако говорите само за цифрови устройства, декодери могат да бъдат разделени на интернет декодери, цифрови сателитни декодери (DVB-S), цифрови наземни декодери (DVB-T) и цифрови цифрови декодери за кабелна телевизия (DVB-C) според основните им функции. И най-новите IPTV приемници.

DigitalTVset-topboxisoneoftheinformationappliances,itisakindofconsumerelectronicsthatallowsuserstowatchdigitalTVprogramsonexistinganalogTVs,andconductinteractivedigitalentertainment,educationandcommercializationactivities.product.

Internetvideo

IPTVisaninteractiveInternetTV.Itisakindofinfrastructurethatutilizesabroadbandnetwork.)”isthemainterminaldevice,providinguserswithnewtechnologiesthatprovideuserswithavarietyofinteractivedigitalmediapersonalizedservicessuchasvideo-on-demand,Internetaccess,ande-mailgames.NetworkTVsoftwarebasedontheP2Pprinciple,butdifferentfromotherP2PnetworkTVs,theserver-sidefunctionisopen,allowinguserstoaddprogramsbythemselves,andprogramsfoundontheInternetcanalsobeadded.BasedontheP2Pprinciple,programscanalsobeadded.

Teletext

Teletextisasubsidiaryserviceoftelevisionbroadcasting.TeletextisananalogTVsystem.TheTVscreendisplays25framesofTVsignalspersecond,with625linesperframe.Eachlinesweepsfromthelefttotherightofthescreen,andeachframeisdividedintotwofieldsandsweepsfromthetoptothebottomofthescreen.Ofthe625linesineachframe,only575linesareactuallydisplayedonthescreen,andtheother50linesarereversetravelandcannotbeseen.Inadditiontotransmittingtestsignals,thereverseprocesscanalsobeusedtotransmitadditionaldatainformation,includinggraphicsandtext.Atthereceivingend,viewerscanuseadedicatedteletextdecodertoviewthetransmittedinformationonthescreen.