Tsev > Exhibition > Ntsiab lus

Kua siv lead ua zaub TV (LCD TV), xim TVs uas siv LCD technology los mus tsim dluab

Apr 21, 2017

LCD TV


Ib tug generic LCD TV, nrog hais lus rau ob sab ntawm lub screen

Kua-crystal-zaub televisions (LCD TV) yog TV poob lawm uas siv kua-siv lead ua qhia rau tsim dluab. LCD TV yog thinner thiab lighter tshaj cathode txoj sab ci raj (CRTs) ntawm zoo xws li cov zaub loj, me, thiab yog muaj nyob rau hauv loj npaum li cas ntau thiab tsawg pab. Thaum raug nqi poob, qhov no ua ke nrog ntawm nta ua LCDs tswv yim rau TV receivers.

Nyob rau hauv 2007, LCD TV surpassed muag khoom ntawm CRT-raws li televisions thoob ntiaj teb rau thawj lub sij hawm, [ citation ntxiv ] thiab lawv qhov muag nuj nqis txheeb ze mus rau lwm cov technologies yog accelerating. LCD TVs yog sai sai displacing qhov loj xwb competitors nyob rau hauv lub loj-screen ua lag luam, cov ntshav zaub vaj huam sib luag thiab rear-projection TV . LCDs yog, yog nyob deb, lub feem ntau lug ua thiab muag TV zaub hom.

LCDs kuj muaj ib tug ntau yam ntawm tsis zoo. Lwm yam technologies nyob rau cov weaknesses, xws li organic teeb-emitting diodes (OLED), pub thiab tab sis , tab sis raws li ntawm 2014 tsis muaj leej twg ntawm cov tau nkag mus rau ntau ntau lawm rau TV qhia.


txheem

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Hauj lwm [ edit ]

Basic LCD tswv yim [ edit ]

LCD TV nyob rau hauv tsev ua ke nrog PlayStation 3 thiab ib co lwm yam khoom

LCD TV tsim ib tug dub thiab dawb lias duab los ntawm xyua filtering ib lub teeb dawb. Lub teeb yog muab los ntawm ib tug series ntawm txias cathode fluorescent teeb (CCFLs) nyob rau tom qab ntawm qhov screen. Niaj hnub no, feem ntau LCD-TV qhia siv dawb los yog dawb lias LEDs li Backlighting xwb. Tsheej lab ntawm cov neeg LCD shutters, teem nyob rau hauv ib daim phiaj, qhib thiab kaw cia ib tug taub txua nqi ntawm lub teeb dawb los ntawm. Txhua shutter yog ua khub nrog ib tug dawb lias lim kom tshem tawm tag nrho tab sis cov liab, ntsuab los yog xiav (RGB) feem ntawm lub teeb los ntawm tus thawj dawb qhov chaw. Txhua shutter-lim khub ntaub ntawv ib zaug xwb sub-pixel. Lub sub-pixels yog li me me hais tias thaum cov zaub yog saib los ntawm txawm tias ib tug luv luv deb, tus neeg xim muab ua ke los tsim ib tug tib cov nqaij ntawd ntawm cov xim, ib tug pixel . Lub ntxoov ntxoo ntawm cov xim yog tshuaj los hloov tus txheeb ze kev siv ntawm lub teeb kis tau los ntawm cov sub-pixels.

Kua muaju encompass ib tug ntau yam ntawm (feem ntau) pas nrig-zoo li tus polymers uas lawm tsim rau hauv nyias, kom khaubncaws sab nraud povtseg, raws li txwv mus rau ntau random kawm tuab si lug ntawm ib tug ib txwm ua kua . Ib txhia ntawm cov no, lub nematic kua muaju, kuj qhia ib qho kawm tuab si lug nyhuv ntawm cov khaubncaws sab nraud povtseg. Cov kev taw qhia ntawm cov kawm tuab si lug ntawm ib tug nematic kua siv lead ua tau teem los tso nws nyob rau hauv kev sib cuag nrog ib tug kawm tuab si lug txheej los yog tus thawj coj, uas yog yeej tseem zoo ib cov ntaub ntawv uas nrog me me grooves nyob rau hauv nws, nyob rau hauv txhawb substrates. Thaum muab tso rau ib tug thawj coj, cov txheej nyob rau hauv kev tiv tauj yuav dlhos nws tus kheej nrog lub grooves, thiab cov khaubncaws sab nraud povtseg saum toj no yuav tom qab dlhos lawv tus kheej nrog rau cov khaubncaws sab nraud povtseg hauv qab no, lub ib thooj khoom noj nyob rau lub thawj coj kawm tuab si lug. Nyob rau hauv cov ntaub ntawv ntawm ib tug Twisted Nematic (TN) LCD, qhov no cov nyhuv yog siv los ntawm kev siv ob directors txheej txheem ntawm txoj cai ces kaum thiab muab tso rau ze ua ke nrog lub kua siv lead ua nruab nrab ntawm lawv. Qhov no forces lub khaubncaws sab nraud povtseg dlhos lawv tus kheej nyob rau hauv ob cov lus qhia, tsim ib cov qauv uas txhua txheej raws li ntawm ib tug me ntsis txawv lub rau qhov sawv daws rau ntawm ob sab.

LCD shutters muaj ib pawg ntawm cov peb thawj cov ntsiab. Nyob rau hauv qab thiab saum toj ntawm lub shutter yog polarizer daim hlau teem rau ntawm txoj cai ces kaum. Feem ntau teeb yuav tsis taug kev los ntawm ib tug khub ntawm polarizers teem nyob rau hauv no zam, thiab cov zaub yuav dub. Lub polarizers kuj muaj cov directors mus tsim lub twisted qauv raws li lub polarizers rau tog twg los sab. Raws li lub teeb ntws tawm ntawm lub rear polarizer, nws yuav lawm raws li cov kua siv lead ua lub twist, teebmeem rau pem hauv ntej ntawm cov kua siv lead ua tau raug kev tig los ntawm qhov tseeb lub, uas tso cai rau nws kis tau los ntawm pem hauv ntej polarizer. LCDs yog feem ntau pob tshab nyob rau hauv no hom ntawm cov lag luam.

Yuav kom tig ib shutter tawm, ib tug voltage yog thov hla nws los ntawm pem hauv ntej rau nram qab. Lub pas nrig-zoo li tus molecules dlhos lawv tus kheej nrog rau cov hluav taws xob field es tsis txhob ntawm tus directors, distorting lub twisted qauv. Lub teeb tsis hloov polarization raws li nws ntws los ntawm cov kua siv lead ua, thiab yuav tsis kis tau los ntawm pem hauv ntej polarizer. Los ntawm kev tswj lub voltage thov thoob plaws lub kua siv lead ua, tus nqi ntawm cov seem twist yuav tau xaiv. Qhov no tso cai rau lub transparency ntawm lub shutter yuav tsum tau tswj. Yuav kom txhim kho switching lub sij hawm, lub hlwb raug muab tso nyob rau hauv siab, uas tsub kom tus quab yuam kom rov dlhos lawv tus kheej nrog rau cov directors thaum lub teb yog muab tua.

Ob peb lwm variations thiab cov kev hloov tau siv nyob rau hauv thiaj li yuav txhim kho kev kawm nyob rau hauv tej yam ntaub ntawv sau npe. Nyob rau hauv-dav hlau Switching qhia (IPS thiab S-IPS) muaj wider saib cov ces kaum thiab zoo xim tu tub tu kiv, tiam sis yog ntau yooj yim los mus tsim thiab muaj me ntsis qeeb qeeb teb lub sij hawm. Vertical Tuab si lug (VA, S-PVA thiab MVA) muaj ntau dua zoo ratios thiab zoo teb lub sij hawm, tab sis txom nyem los ntawm cov xim shifting thaum saib los ntawm lub sab. Nyob rau hauv Feem ntau, tag nrho cov ntawm cov qhia ua hauj lwm nyob rau hauv ib tug zoo li zam los tswj cov polarization ntawm lub teeb qhov chaw.

Hais sub-pixels [ edit ]

Ib tug nyob ze-up (300 ×) pom ntawm ib tug raug LCD, kom meej meej qhia lub sub-pixel qauv. Lub "thais" nyob rau hauv rau sab laug ntawm txhua sub-pixel yog lub nyias-zaj duab xis transistor. Lub txuam capacitors thiab hais kab nyob ib ncig ntawm lub shutter, nyob rau hauv qhov tsaus ntuj nti chaw.

Nyob rau hauv thiaj li yuav nyob ib zaug xwb shutter rau ntawm cov zaub, ib tug series ntawm electrodes yog tso rau cov phiaj rau ntawm ob sab ntawm cov kua siv lead ua. Ib sab muaj kab rov tav kab txaij uas tsim kab, lwm yam muaj ntsug kab txaij uas tsim txhua. By muab voltage rau ib tug kab thiab ib kem, ib tug teb yuav tsum generated ntawm tus taw tes qhov twg lawv hla. Txij li thaum ib tug hlau electrode yuav opaque, LCDs siv electrodes ua los ntawm ib tug pob tshab xyuas pib, feem ntau indium tin oxide .

Txij li thaum hais ib zaug xwb shutter yuav tsum tau hwj chim yuav tsum tau nkag mus rau ib qho tag nrho cov kab thiab sab, ib co ntawm cov teb yeej ib txwm txia tawm mus rau hauv lub surrounding shutters. Kua muaju yog heev rhiab, thiab txawm me me ntawm leaked teb yuav ua rau ib txhia theem ntawm switching tshwm sim. Qhov no ib nrab switching ntawm surrounding shutters blurs lub resulting duab. Ib qho teeb meem nyob rau hauv thaum ntxov LCD systems yog tus voltages yuav tsum tau mus teem lub shutters mus rau ib tug kev twist yog heev tsawg, tab sis hais tias voltage yog tsawg tsawg heev yuav ua rau cov muaju rov dlhos nrog tsim nyog ua tau zoo. Qhov no ua rau qeeb teb lub sij hawm thiab coj mus rau yooj yim pom " ghosting " rau cov qhia nyob rau hauv fast-tsiv dluab, zoo li ib tug nas cursor rau ib tug computer screen. Txawm scrolling ntawv nyeem feem ntau nws raws li ib tug nyeem plooj, thiab cov switching ceev yog nyob deb heev qeeb siv raws li ib tug pab tau cov tshooj TV hauv zaub.

Nyob rau hauv thiaj li yuav tua tau cov teeb meem, niaj hnub LCDs siv ib tug active matrix tsim. Es tsis txhob powering ob electrodes, ib pawg, feem ntau cov pem hauv ntej, yog txuas mus rau ib qho av. Nyob rau tsheb, txhua shutter yog ua khub nrog ib tug nyias zaj duab xis-transistor uas keyboards nyob rau hauv cov lus teb rau lug cais voltage ntau ntau, hais 0 thiab +5 volts. Ib tug tshiab hais kab, lub rooj vag kab, ntxiv raws li ib tug nyias muaj nyias ib tes hloov qhov rau lub transistors. Cov kab thiab txhua yog nyob raws li ua ntej, tab sis lub transistors xyuas kom meej tias tsuas yog tus ib shutter lem taw tes yog hais; tej leaked teb yog heev me me mus rau hloov surrounding transistors. Thaum hloov rau, ib qhov thiab siab kuj nqi xwb ntws los ntawm cov qhov kab los ntawm lub transistor thiab mus rau hauv ib qho txuam capacitor . Lub capacitor yog them kom txog thaum nws tuas qhov tseeb tswj voltage, maj mam to qhov no los ntawm tus siv lead ua rau ib qho av. Tus tam sim no yog heev ceev ceev thiab tsis haum rau zoo tswj ntawm lub resulting khw xwb, li ntawd, mem tes code tes taws los piav yog siv los yog tswj tag nrho cov txaus. Tsis tsuas yog tsis no pub rau meej heev tswj lub shutters, txij thaum lub capacitor yuav tau sau los yog drained sai sai, tab sis lub teb lub sij hawm ntawm lub shutter yog dramatically zoo tuaj zoo li.

Lub tsev ib cov zaub [ edit ]

Ib tug raug shutter los ua ke muaj ib tug nyuaj ob peb khaubncaws sab nraud povtseg tso nyob rau hauv ob nyias iav los xij txoj kev rau pem hauv ntej thiab rov tom qab ntawm cov zaub. Rau me me zaub ntau thiab tsawg pab (nyob rau hauv 30 nti (760 hli)), lub iav los xij yuav tsum tau hloov nrog yas.

Lub rear ntawv pib nrog ib tug polarizing zaj duab xis, cov iav ntawv, lub active matrix Cheebtsam thiab hais electrodes, thiab ces tus thawj coj. Lub pem hauv ntej ntawv no zoo sib xws, tab sis tsis muaj tus nquag matrix Cheebtsam, hloov cov neeg uas muaj patterned xim cov ntxaij lim dej. Siv ib tug multi-kauj ruam siv cov txheej txheem, ob qho tib si los xij yuav tau ua nyob rau hauv tib los ua ke kab. Cov kua siv lead ua yog muab tso rau nruab nrab ntawm ob los xij nyob rau hauv ib tug patterned yas ntawv uas faib lub kua rau hauv ib tug neeg shutters thiab ua rau cov ntawv txheeb ntawm ib tug leej deb ntawm txhua lwm yam.

Cov tseem ceeb heev kauj ruam nyob rau hauv lub tsim txoj kev yog lub deposition ntawm lub active matrix Cheebtsam. Cov no muaj ib tug kuj siab tsis ua hauj lwm tus nqi, uas renders cov pixels rau qhov kev tshuaj ntsuam "ib txwm nyob rau". Yog hais tias muaj txaus lawm pixels, qhov kev tshuaj ntsuam yuav tsum tau muab pov tseg. Cov nab npawb ntawm cov muab pov tseg panels muaj ib tug muaj zog ntxim rau cov nqi ntawm lub resulting TV poob lawm, thiab cov loj downward lub caij nplooj zeeg nyob rau hauv pricing ntawm 2006 thiab 2008 yog vim feem ntau mus txhim kho dab.

Yuav kom tsim ib tug ua tiav TV, tus shutter los ua ke ua ke nrog tswj electronics thiab backlight. Cov backlight rau me me poob lawm yuav tsum yog muab los ntawm ib tug tib teeb siv ib diffuser los yog Frosted iav kom kis tau tawm lub teeb, tab sis loj qhia ib zaug xwb teeb yog tsis kaj txaus thiab lub tsheb nto es tsis txhob them nrog ib tug xov tooj ntawm cais teeb. Tau raws li txawm teeb pom kev zoo tshaj rau pem hauv ntej ntawm ib tug tag nrho cov zaub tseem yog ib tug kev sib tw, thiab kaj thiab tsaus me ntsis yog tsis yooj yim dua.

Piv [ edit ]

A 19 " Sony LCD TV

Ntim [ edit ]

Nyob rau hauv ib tug CRT lub electron nqaj yog ua los ntawm cua sov ib tug hlau filament, uas "boils" electrons tawm nws saum npoo. Lub electrons ces ceev thiab teem nyob rau hauv ib tug electron phom , thiab tswj kom qhov chaw nyob rau qhov kev tshuaj ntsuam kev siv electromagnets . Feem ntau ntawm lub hwj chim kev siv nyiaj txiag ntawm ib tug CRT nkag mus rau hauv cua sov rau cov filament, uas yog vim li cas tom qab ib tug CRT-raws li TV yog kub. Txij li thaum lub electrons yog yooj yim deflected los ntawm cov pa roj molecules, tag nrho cov raj yuav tsum tau muaj nyob rau hauv lub tshuab nqus tsev. Lub atmospheric quab yuam nyob rau hauv lub ntsej muag ntawm lub raj hlob nrog lub cheeb tsam, uas yuav tsum tau puas-thicker iav. Qhov no txwv tswv yim CRTs rau ntau thiab tsawg pab nyob ib ncig ntawm 30 nti; (76 cm) qhia txog li 40 nti (102 cm) tau ua tab sis tiv kev txom nyem ob peb puas phaus, thiab televisions loj tshaj no yuav tsum tau tig mus rau lwm yam yees li rear-projection .

Qhov uas tsis muaj lub tshuab nqus tsev nyob rau hauv ib tug LCD TV yog ib qho ntawm nws zoo; muaj yog ib tug me me npaum li cas ntawm lub tshuab nqus tsev nyob rau hauv poob lawm siv CCFL Backlights, tab sis qhov no yog cov txheej txheem ntawm nyob rau hauv thooj voos kheej kheej uas yog lawm muaj zog tshaj loj tiaj tus paib. Tshem qhov yuav tsum tau rau hnyav iav ntsej muag pub LCDs yuav ntau sib zog tshaj lwm yam technologies. Piv txwv li, lub Ntse LC-42D65, ib tug ncaj raug 42-nti (106 cm) LCD TV, nyhav 55 lbs (25 kg) xws li ib tug kev muag zaub, [1] thaum lub caij qauv Sony KV-40XBR800, ib tug 40 "( 102 cm) 4: 3 CRT nyhav ib tug loj heev 304 lbs (138 kg) tsis muaj ib tug sawv, yuav luag rau lub sij hawm tus luj. [2]

LCD panels, zoo li lwm yam pav ca vaj huam sib luag qhia , yog tseem ntau thinner tshaj CRTs. Txij li thaum lub CRT tsuas khoov lub electron nqaj los ntawm ib tug tseem ceeb heev lub sij hawm tseem tswj kom pom tseeb, lub electron phom yuav tsum tau nyob deb ntawm cov pem hauv ntej lub ntsej muag ntawm lub TV. Nyob rau hauv thaum ntxov poob lawm los ntawm lub sijhawm xyoo 1950 lub kaum sab xis yog feem ntau raws li me me raws li 35 degrees off-axis, tab sis kev txhim kho, tshwj xeeb tshaj yog computer pab convergence, cia kev yuav tsum tau dramatically zoo tuaj thiab, lig nyob rau hauv lawv cov evolution, daim ntau quav tso. Cuaj kaum, txawm qhov zoo tshaj plaws CRTs yog npaum li cas ntxaum tshaj ib tug LCD; lub KV-40XBR800 yog 26 nti (66 cm) sib sib zog nqus, [2] thaum lub LC-42D65U yog tsawg tshaj li 4 inches (10 cm) tuab [1] - nws stand yog npaum li cas ntxaum tshaj qhov screen nyob rau hauv thiaj li yuav muab stability.

LCDs yuav, nyob rau hauv kev tshawb xav, yuav ua tau rau tej me me, nrog ntau lawm loo ua tus thawj constraint. Raws li yields ntau zog, ntau LCD screen ntau thiab tsawg pab loj hlob, los ntawm 14 "(35 cm) mus rau 30" (70 cm), mus rau 42 "(107 cm), ces 52" (132 cm), thiab 65 "(165 cm) poob lawm yog tam sim no muaj dav. Qhov no pub LCDs los lwv ncaj qha nrog rau feem ntau nyob rau hauv-lub tsev projection TV poob lawm, thiab nyob rau hauv kev sib piv rau cov neeg yees ncaj-saib LCDs muaj ib tug duab zoo zoo. Seb thiab tsawg mus dhia poob lawm no muaj nyob nrog ntau thiab tsawg pab tshaj 100 nti (254 cm ).

Efficiency [ edit ]

LCDs no kuj inefficient nyob rau hauv cov nqe lus ntawm lub hwj chim kev siv ib zaub loj, me, vim hais tias feem coob ntawm cov teeb uas yog ua nyob rau tom qab ntawm qhov screen yog sim ua ntej nws nce mus txog tus tuav. Yuav pib nrog, lub rear polarizer lim tawm ntau tshaj ib nrab ntawm cov thawj un-polarized lub teeb. Coj cov duab saum toj no, koj yuav pom tias ib tug zoo feem ntawm qhov kev tshuaj ntsuam cheeb tsam no yog them los ntawm lub cell qauv nyob ib ncig ntawm lub shutters, uas tshem tawm lwm ntawm. Tom qab hais tias, txhua sub-pixel lub xim lim tuskheej feem ntau ntawm yog dab tsi yog sab laug mus rau tawm tsuas yog tus yam xim. Thaum kawg, los tswj cov xim thiab cov luminance ntawm ib tug pixel raws li ib tug tag nrho, ib co teeb yog poob thaum dua rau pem hauv ntej polarizer nyob rau hauv lub on-lub xeev los ntawm cov neeg txhaum lub lag luam ntawm lub shutters.

Rau cov yog vim li cas lub Backlighting system muaj yuav tsis tshua muaj hwj chim loj. Nyob rau hauv cov kev phem ntawm kev siv heev npaum CCFLs, feem ntau poob lawm siv ob peb puas watts ntawm lub hwj chim, ntau tshaj yuav tsum mus rau lub teeb ib tug tag nrho lub tsev nrog rau cov tib technology. Raws li ib tug tshwm sim, LCD TV siv CCFLs mus nrog zuag qhia tag nrho pab xws li ib tug CRT ntawm tib yam loj. Siv cov tib piv txwv, cov KV-40XBR800 dissipates 245 W, [2] thaum lub LC-42D65 dissipates 235 W. [1] Ntshav qhia yog zuj zus; qhov zoo tshaj plaws yog nyob rau hauv par nrog LCDs, tab sis raug poob lawm kos ntau npaum li cas. [3]

Niaj hnub nimno LCD poob lawm tau npaj rau qhov chaw nyob rau hauv lub hwj chim kev siv los ntawm ib tug txheej txheem lub npe hu ua "dynamic teeb pom kev zoo" (Ameslikas nkag tau rau lwm yam, saib hauv qab no). Qhov no system tshuaj xyuas cov duab mus nrhiav tej thaj chaw uas yog ib tsos tsaus tsawv, thiab thiaj li muaj Backlighting nyob rau hauv cov cheeb tsam. CCFLs yog ntev thooj voos kheej kheej uas khiav qhov ntev ntawm lub screen, li ntawd, qhov kev hloov no yuav tsuas yuav siv los tswj tus brightness ntawm qhov kev tshuaj ntsuam raws li ib tug tag nrho, los yog tsawg kawg dav kab rov tav bands ntawm nws. Qhov no ua rau cov txheej txheem tsim tsuas yog rau cov kev hom ntawm cov dluab, zoo li tus qhab nia nyob rau thaum xaus ntawm ib tug yeeb yam. Nyob rau hauv 2009 ib co manufacturers [4] los ua ib co TVs siv HCFL (ntau zog npaum li CCFL). Poob lawm siv faib LEDs qab lub screen, nrog txhua LED teeb pom kev zoo tsuas muaj tsawg tus pixels, feem ntau ib tug 16 los ntawm 16 thaj, cia rau cov zoo dua zos dimming los ntawm dynamically kho cov brightness ntawm ntau me me chaw, uas yog haum rau ib tug npaum li cas wider txheej dluab.

Lwm tu ncua cheeb tsam ntawm kev tshawb fawb yog siv cov ntaub ntawv uas optically lawv lub teeb nyob rau hauv thiaj li yuav rov siv tau raws li ntau ntau lub teeb liab li sai tau. Ib tug tej zaum txoj kev txhim kho yog siv microprisms los yog dichromic tsom iav phua lub teeb rau hauv R, G thiab B, es tsis txhob ntawm absorbing hauv pliaj xim nyob rau hauv ib lub lim. Ib tug muaj kev vam meej system yuav txhim kho efficiency los ntawm peb lub sij hawm. Lwm yuav mus ncaj rau lub teeb uas yuav nquag poob rau opaque ntsiab rov qab mus rau hauv lub pob tshab ntawm lub shutters.

Ob peb newer technologies, OLED , pub thiab tab sis , muaj tsawg hwj chim siv raws li ib tug ntawm lawv thawj zoo. Tag nrho cov technologies ncaj qha tsim teeb nyob rau hauv ib tug sub-pixel hauv paus, thiab siv tsuas yog raws li ntau hwj chim raws li hais tias lub teeb theem yuav tsum tau. Sony tau pom 36 "pub units displaying qaim heev dluab nqus tsuas yog 14 W, tsawg tshaj li 1/10 li ntau li ntau ib tug piv sized LCD. OLEDs thiab SEDs zoo xws li FEDs nyob rau hauv hwj chim cov nqe lus. Lub sab fais fab yuav tsum ua cov yees nthuav tshwj xeeb tshaj nyob rau hauv muaj hwj huam siv li laptop computers thiab txawb tes . cov hom pab kiag li lawm yog cov lag luam uas muas thaum chiv thawj bootstrapped LCD technology, vim nws lub teeb yuag thiab thinness.

Duab zoo [ edit ]

Ib tug traveler hnab tshos loj LCD TV

Early LCD poob lawm tau dav derided rau lawv pluag tag nrho cov duab zoo , feem ntau notably lub ghosting rau fast-tsiv dluab, cov neeg pluag zoo ratio, thiab muddy xim. Nyob rau hauv cov kev phem ntawm ntau txoj hau kev uas lwm yam yees yuav yeej ib txwm yeej LCDs, loj heev nyob rau hauv peev LCD ntau lawm, manufacturing, thiab hluav taws xob cov duab ua tau hais ntau yam ntawm cov kev txhawj xeeb.

Lo lus teb lub sij hawm [ edit ]

Rau 60 ntas ib ob video, ntau nyob rau hauv North America, txhua pixel yog lit rau 17 ms ua ntej nws yuav tsum tau rov twv (ntawm 50 ntas ib ob, nws yog 20 ms nyob rau hauv cov teb chaws Europe). Early LCDs muaj teb lub sij hawm nyob rau hauv qhov kev txiav txim ntawm pua pua ntawm milliseconds, uas ua rau lawv puas rau TV. Ib tug ua ke ntawm kev txhim kho nyob rau hauv cov ntaub ntawv technology txij thaum lub xyoo 1970 paub heev no, raws li tus active matrix hom kev kawm. By 2000, LCD panels nrog teb lub sij hawm ib ncig 20 ms twb kuj ntau nyob rau hauv computer cwj pwm. Qhov no yog tseem tsis ceev ceev txaus rau TV siv.

Ib tug loj kev txhim kho, tho los ntawm NEC , coj mus rau tus thawj tswv yim LCD TV. NEC pom tias cov kua muaju siv ib co sij hawm mus pib tsiv mus rau hauv lawv cov tshiab orientation, tab sis tsis txhob sai heev. Yog hais tias cov thawj zaug zog yuav tau ceev, lub zuag qhia tag nrho kev kawm yuav muab ntau zog. NEC lub tshuaj yog rau boost lub voltage thaum lub sij hawm "saws pem lub sij hawm" thaum lub capacitor yog chiv raug them, thiab ces xa me nyuam rov qab mus rau qub ntau ntau rau sau nws mus rau lub yuav tsum tau voltage. Ib tug ntau txoj kev yog mus dua zaum ob tus voltage, tab sis cais tus mem tes dav, delivering tus tib tag nrho cov nyiaj ntawm lub hwj chim. Npe hu ua "overdrive" los ntawm NEC, tus txheej txheem yog tam sim no dav siv nyob rau hauv yuav luag tag nrho cov LCDs.

Lwm loj txoj kev txhim kho nyob rau hauv teb lub sij hawm twb tiav los ntawm kev ntxiv lub cim xeeb los tuav lub txheem ntawm cov zaub - ib yam dab tsi uas ib tug TV yuav tsum tau ua lawm, tab sis twb tsis muas thaum chiv thawj yuav tsum tau nyob rau hauv lub computer saib luag hauj lwm uas bootstrapped lub LCD kev lag luam. Nyob rau hauv cov laus qhia cov active matrix capacitors twb xub drained, thiab ces sam mus rau qhov tshiab tus nqi nrog rau txhua txhua refresh. Tab sis nyob rau hauv Feem ntau, qhov loj feem ntau ntawm cov kev tshuaj ntsuam tus duab tsis hloov los ntawm ncej xwm. By tuav tus ua ntej thiab tom qab qhov tseem ceeb nyob rau hauv computer nco , muab piv rau lawv, thiab tsuas yog resetting cov sub-pixels uas ua tau hloov, tus nqi ntawm cov sij hawm siv them thiab ntxub cov capacitors twb txo. Ntxiv mus, lub capacitors tsis drained kiag li; es tsis txhob, lawv twb muaj lawm xwb theem yog yog ntau zog los yog poob mus rau phim tus tshiab tus nqi, uas feem ntau yuav tsum tau tsawg dua them pulses. Qhov kev hloov no, uas twb cais rau tus neeg tsav tsheb electronics thiab pheej yig los siv, zoo teb lub sij hawm los ntawm hais txog ob lub sij hawm.

Ua ke, nrog rau txuas ntxiv txhim kho nyob rau hauv cov kua muaju lawv tus kheej, thiab los ntawm kev ua refresh nqi ntawm 60 Hz mus rau 120 thiab 240 Hz, teb lub sij hawm poob los ntawm 20 ms nyob rau hauv 2000 mus txog 2 ms nyob rau hauv qhov zoo tshaj plaws niaj hnub qhia. Tab sis txawm qhov no yog tsis ceev heev txaus vim hais tias cov pixel yuav tseem yuav switching thaum tus ncej yog tso tawm kom pom. Pa CRTs yog zoo nyob rau hauv 1 ms, thiab ntshav thiab OLED lus khav lub sij hawm nyob rau hauv qhov kev txiav txim ntawm 0,001 ms.

Ib txoj kev uas yuav ntxiv txhim kho lub zoo refresh tus nqi yog siv "super-zauv", thiab nws yog ua nce ntau rau high-end poob lawm. Txij li thaum lub blurring ntawm cov lus tsa suab muaj tshwm sim thaum lub sij hawm kev hloov los ntawm ib lub xeev mus rau lwm lub, qhov no yuav txo los ntawm ob npaug refresh tus nqi ntawm lub LCD vaj huam sib luag, thiab lub tsev intermediate ntas siv ntau yam suab nyiaj hom kev kawm. Qhov no smooths tawm lub zaus, thiab txhais tau tias lub Backlighting yog muab rau thaum lub zaus yog tswm. Ib tug xov tooj ntawm high-end poob lawm muaj 120 Hz (nyob rau hauv North America) los yog 100 Hz (nyob rau hauv cov teb chaws Europe) tshiab cov nqi siv cov txheej txheem no. Lwm cov tshuaj yog tsuas yog tig lub Backlighting rau thaum lub shutter tau siab hloov. Nyob rau hauv thiaj li yuav xyuas kom meej tias cov zaub tsis flicker, cov tshuab hluav taws lub Backlighting ob peb lub sij hawm ib refresh, nyob rau hauv ib tug zam zoo xws li cov movie projection qhov twg lub shutter qhib thiab kaw ob peb lub sij hawm ib tus ncej.

Zoo piv [ edit ]

Txawm nyob rau hauv ib tug tag nrho switched-off xeev, kua muaju cia ib co teeb rau paim quav los ntawm cov shutters. Qhov no txwv lawv zoo ratios mus txog 1600: 1 nyob rau hauv qhov zoo tshaj plaws niaj hnub poob lawm, thaum ntsuas siv cov ANSI ntsuas (ANSI IT7.215-1992). Manufacturers feem ntau hais cov "Puv On / Off" zoo piv xwb, uas yog hais txog 25% ntau dua rau twg muab teeb. [5]

Qhov no tsis muaj contrast yog feem ntau hnov nyob rau hauv ib tsos tsaus tsawv scenes. Yuav kom tso saib ib cov xim ze rau dub, lub LCD shutters yuav tsum tau tig mus rau yuav luag tag nrho cov opacity, limiting tus xov tooj ntawm discrete xim lawv yuav tso saib. Qhov no ua rau "posterizing" los thiab bands ntawm discrete xim uas ua pom nyob rau hauv ntxoov ntxoo, uas yog vim li cas muaj ntau yam kev xyuas txog LCD TVs hais lub "duab ntxoov ntxoo nthuav dav". [6] Nyob rau hauv kev sib piv, lub siab tshaj plaws-end LED TVs muaj kev zoo ratios ntawm 5.000.000: 1.

Txij li thaum tag nrho cov nqi ntawm lub teeb xeeb tus tuav yog ib tug ua ke ntawm cov Backlighting thiab shuttering, niaj hnub poob lawm yuav siv "dynamic Backlighting" los yog hauv zos dimming los txhim kho lub zoo piv thiab duab ntxoov ntxoo nthuav dav. Yog hais tias ib tug kev thaj tsam ntawm lub screen yog tsaus, ib tug pa txheej yuav tau teem nws shutters ze rau opaque mus txiav down lub teeb. Txawm li cas los, yog hais tias tus Backlighting yog txo los ntawm ib nrab nyob rau hauv cheeb tsam ntawd, cov shuttering yuav txo los ntawm ib nrab, thiab tus naj npawb ntawm muaj shuttering theem nyob rau hauv lub sub-pixels doubles. Qhov no yog lub ntsiab yog vim li cas high-end poob lawm muaj dynamic teeb pom kev zoo (li opposed rau lub hwj chim nyiaj, hais ua ntej lawm), uas lub zoo piv hla qhov screen yuav tsum tau dramatically zoo tuaj. Thaum lub LCD shutters muaj peev xwm ntawm ua txog 1000: 1 zoo ratio, los ntawm kev ntxiv 30 ntau ntau ntawm dynamic Backlighting no yog kho kom 30,000: 1.

Txawm li cas los, lub cheeb tsam ntawm qhov kev tshuaj ntsuam uas yuav dynamically tom yog ib tug muaj nuj nqi ntawm lub Backlighting qhov chaw. CCFLs yog nyias hlab uas taws ntau kab (los yog kab) nyob rau hauv tag nrho screen ib zaug, thiab hais tias lub teeb yog kis tau tawm nrog diffusers. Lub CCFL yuav tsum tau tsav nrog hwj huam txaus mus rau lub teeb lub brightest thaj tsam ntawm lub feem ntawm cov duab nyob rau hauv pem hauv ntej ntawm nws, li ntawd, yog hais tias tus duab no yog lub teeb nyob rau ib sab thiab tsaus ntuj nti nyob rau lwm yam, cov txheej txheem no yuav siv tsis tau ntse. Qhia backlit los ntawm tag nrho cov arrays ntawm LEDs muaj ib tug kom zoo dua, vim hais tias txhua LED teeb xwb ib tug me me chav ntawm lub screen. Qhov no tso cai rau lub dynamic Backlighting yuav tsum tau siv nyob rau hauv ib tug ntau dav ntau yam ntawm cov dluab. Ntug-zes qhia tsis txaus siab rau qhov no kom zoo dua. Cov qhia muaj LEDs tsuas raws tus npoo thiab siv ib lub teeb qhia phaj them nrog phav phav ntawm convex pob uas muaj kev cuam tshuam lub teeb los ntawm cov sab-firing LEDs tawm los ntawm lub LCD matrix thiab cov ntxaij lim dej. LEDs rau ntug-zes qhia yuav tsum dimmed tsuas thooj plawv, tsis ib lub zuj zus. Rau nqi yog vim li cas, feem ntau ntawm LCD TVs muaj ntug-zes Backlighting.

Lub loj heev nyob rau hauv-daim ntawv boost no txoj kev muab yog vim li cas muaj ntau yam poob lawm tam sim no muab cov "dynamic zoo piv" nyob rau hauv lawv cov specifications los xij. Muaj coob leej ntau tus sib cav tswv yim nyob rau hauv lub audio-visual ntiaj teb no raws li seb los yog tsis dynamic zoo ratios yog tiag tiag, los yog tsuas yog ua li hais lus. [7] [8] reviewers kheev nco ntsoov hais tias txawm qhov zoo tshaj plaws LCDs yuav tsis phim tus zoo ratios los yog sib sib zog nqus dub ntawm ntshav qhia, nyob rau hauv cov kev phem ntawm raug nyob, rau ntawm daim ntawv, raws li muaj ntau dua ratios. Txawm li cas los, txij li thaum 2014 muaj cov tsis muaj loj manufacturers ntawm ntshav qhia sab laug. Zoo cov thawj coj yog tam sim no qhia raws li OLEDs.

Xim gamut [ edit ]

Xim rau ib tug LCD TV yog ua los ntawm filtering cia ib tug dawb qhov twg los thiab ces xaiv shuttering peb thawj xim txheeb ze rau txhua tus lwm yam. Cov raug thiab zoo tshaj ntawm cov ua xim yog li nyob rau ntawm lub Backlighting qhov twg los thiab nws muaj peev xwm tusyees tsim teeb dawb. Lub CCFLs siv nyob rau hauv thaum ntxov LCD TV twb tsis yog tshwj xeeb dawb, thiab tended yuav muaj zog nyob rau hauv zaub ntsuab. Niaj hnub nimno Backlighting tau zoo li no, thiab poob lawm ntau hais ib co lus ib cov xim qhov chaw yuav tsum vov txog 75% ntawm lub NTSC 1953 xim gamut . Siv dawb LEDs li cov backlight pab txoj kev no ntxiv lawm.

Nyob rau hauv lub Cuaj Hli Ntuj 2009 Nanoco , ib tug UK lub tuam txhab, tshaj tawm hais tias nws tau kos npe rau ib tug sib koom txoj kev loj hlob daim ntawv cog lus nrog ib tug loj Japanese electronics lub tuam txhab nyob rau hauv uas nws yuav tsim qauv thiab tsim quantum dots (QD) rau siv nyob rau hauv LED Backlights nyob rau hauv LCD TV. [9] Quantum dots yog muaj nuj nqis rau qhia, vim hais tias lawv emit teeb nyob rau hauv heev Gaussian distributions . [10] Qhov no yuav ua tau nyob rau hauv ib tug zaub uas ntau meej renders cov xim uas tib neeg qhov muag yuav pom. Yuav kom tsim teeb dawb zoo tshaj plaws suited li ib tug LCD backlight, qhov chaw ntawm lub teeb ntawm ib tug xiav-emitting LED yog hloov los ntawm quantum dots rau hauv me me-bandwidth ntsuab thiab lub teeb liab xws li hais tias lub neej coj lub teeb dawb pub rau ib tug ze li ntawm zoo tagnrho cov xim gamut generated los ntawm cov xim cov ntxaij lim dej ntawm lub LCD vaj huam sib luag. Nyob rau hauv tas li ntawd, efficiency yog zoo, raws li intermediate xim (wavelengths) yuav tsis tuaj lawm thiab tsis muaj yuav tsum tau lim los ntawm lub RGB xim cov ntxaij lim dej ntawm lub LCD screen. US lub tuam txhab QD pom kev ua hauj lwm nrog Sony tso LCD TVs siv cov txheej txheem no nyob rau hauv lub lag luam daim ntawv lo Triluminos nyob rau hauv 2013.

Thaum lub Consumer Electronics Show 2015, Samsung Electronics , LG Electronics , Suav TCL Corporation thiab Sony tsom QD-enhanced LED-Backlighting ntawm LCD TV. [11] [12]

Keeb kwm [ edit ]

Ib tug LCD TV dai rau ib lub phab ntsa nyob rau hauv lub Taipei World Trade Center thaum lub sij hawm Computex Taipei qhia nyob rau hauv 2008.

Early kev [ edit ]

Passive matrix LCDs thawj los ua ntau nyob rau hauv lub 1980s rau ntau yam portable computer cwj pwm. Thaum lub sij hawm lawv sib nrog ntshav qhia nyob rau hauv tib lub lag luam chaw. Lub LCDs muaj qeeb heev refresh nqi uas qhov muag plooj qhov screen txawm nrog scrolling ntawv nyeem, tab sis lawv lub teeb yuag thiab tsis muaj nqi twb loj cov kev pab cuam. Cov ntxaij vab tshaus siv paab LCDs yuav tsum tau tsis nrog lub teeb qhov chaw, uas ua rau lawv yog tshwj xeeb zoo suited rau laptop computers.

Refresh nqi ntawm thaum ntxov pab kiag li lawm twb dhau lawm qeeb yuav pab tau rau TV. Portable televisions yog ib tug lub hom phiaj hauv daim ntawv thov rau LCDs. LCDs noj deb tsawg roj teeb hwj chim ces txawm lub tej yam me me hlab siv nyob rau hauv portable televisions ntawm lub era. Lub earliest muag ua LCD TV yog lub Casio TV-10 ua nyob rau hauv 1983. [13] Kev Txiav Txim Siab tau tas rau txuj txhais , txawm hais tias ib tug xov tooj ntawm technologies tau thawb qhia ntawm cov kev txwv ntawm uas txheem; Super VHS muaj paub xim saturation, thiab DVDs ntxiv dua uas yuav kho tau zoo li. Txawm muaj tej kev kho, kev tshuaj ntsuam ntau thiab tsawg pab tshaj 30 "yog tsawg raws li cov hom yuav pib tshwm blocky ntawm tej zaum mus thaum pub rau loj cov ntxaij vab tshaus. Projection systems tau feem ntau yog tas rau lub sijhawm twg cov duab yuav tsum tau muab saib los ntawm ib tug loj cov neeg tuaj saib.

Cuaj kaum, ib txhia kws nrog LCD TV coj qhov chaw thaum lub sij hawm lub sij hawm no. Nyob rau hauv 1988, Ntse Corporation qhia cov thawj coj mus muag LCD TV, ib tug 14 "qauv nrog active matrix hais siv nyias-zaj duab xis transistors (TFT). Cov twb muaj feem raws li boutique khoom rau muaj tswvyim thiab txawj cov neeg muas zaub, thiab twb tsis tswj cov kev ua lag luam. Thaum tib lub sij hawm, ntshav qhia yuav yooj yim muaj cov kev kawm uas yuav tsum tau ua ib tug zoo sau, tab sis txom nyem los ntawm tsis muaj qhov ci thiab lub siab heev zog noj. Txawm li cas los, ib tug series ntawm cov kev kho tshiab coj mus rau ntshav qhia outpacing LCDs nyob rau hauv kev kawm kev txhim kho, pib nrog Fujitsu tus zoo siv hom kev kawm nyob rau hauv 1979, Hitachi tus paub phosphors nyob rau hauv 1984, thiab AT & T 's tshem tawm ntawm cov dub chaw ntawm lub sub-pixels nyob rau hauv nruab nrab-1980s. By lub caij 1980s, ntshav qhia nyob deb nyob rau hauv ua ntej ntawm LCDs.

High-txhais [ edit ]

Nws yog tus qeeb standardization ntawm siab txhais TV uas thawj ua ib lub lag luam rau cov tshiab TV technologies. Nyob rau hauv kev, lub dav 16: 9 nam piv ntawm cov khoom tshiab yog tsis yooj yim los tsim kom tau siv CRTs; tob ib CRT yuav tsum yuav zoo kawg nkaus yeej nyob rau hauv thiaj li yuav zoo tshaj plaws muaj nws nrog lub tshuab nqus tsev, thiab raws li cov nam piv yuav ntau lub nws yuav yooj yim dua rau ua cov hlab. Nyob rau tib lub sij hawm, qhov ntau dua uas yuav kho tau cov tshiab tawm tswv muaj tau ploj mus lawm thaum me me tshuaj ntsuam ntau thiab tsawg pab, yog li CRTs ntsib tus ntxaib teeb meem ntawm qhov loj thiab ntau lub nyob rau tib lub sij hawm. LCDs ntawm lub era twb tseem tsis tau paub daws fast-tsiv dluab, tshwj xeeb tshaj yog nyob rau hauv ntau dua uas yuav kho tau, thiab los ntawm nruab nrab-Kwvyees li xyoo 1990 cov ntshav zaub yog cov tiag tiag xwb offering nyob rau hauv lub siab daws teeb meem qhov chaw.

Los ntawm cov halting kev taw qhia ntawm HDTV nyob rau hauv nruab nrab-Kwvyees li xyoo 1990 mus rau hauv thaum ntxov 2000s, ntshav qhia yog cov thawj high-txhais zaub technology. Txawm li cas los, lawv cov nqi, ob leeg raug thiab nyob rau hauv txoj kev, meant tias cov laus yees li CRTs khaws cia ib tug hneev taw nyob rau hauv cov kev phem ntawm lawv disadvantages. LCD, txawm li cas los, twb dav tias yuav tsis tau teev rau hauv tib qhov chaw, thiab nws tau lug ntseeg hais tias cov khiav mus rau high-txhais yuav thawb nws los ntawm cov lag luam nkaus.

Qhov no qhov teeb meem hloov sai heev. Contrary mus rau thaum ntxov optimism, ntshav qhia yeej tsis pom tus loj heev kev tuav nyiaj txiaj ntawm scale uas tau leej twg, thiab tseem kim heev. Meanwhile, LCD yees li overdrive pib mus rau qhov chaw lawv muaj peev xwm mus ua hauj lwm nyob rau ntawm lub TV speeds. Initially produced at smaller sizes, fitting into the low-end space that plasmas could not fill, LCDs started to experience the economies of scale that plasmas failed to achieve. By 2004, 32" models were widely available, 42" sets were becoming common, and much larger prototypes were being demonstrated.

Market takeover [ edit ]

Although plasmas continued to hold an arguable picture quality edge over LCDs, and even a price advantage for sets at the critical 42" size and larger, LCD prices started falling rapidly in 2006 while their screen sizes were increasing at a similarly rapid rate. By late 2006, several vendors were offering 42" LCDs, albeit at a price premium, encroaching on plasma's only stronghold. More critically, LCDs offer higher resolutions and true 1080p support, while plasmas were stuck at 720p , which made up for the price difference. [14]

Predictions that prices for LCDs would drop rapidly through 2007 led to a "wait and see" attitude in the market, and sales of all large-screen televisions stagnated while customers watched to see if this would happen. [14] Plasmas and LCDs reached price parity in 2007, at which point the LCD's higher resolution was a winning point for many sales. [14] By late 2007, it was clear that LCDs were going to outsell plasmas during the critical Christmas sales season. [15] [16] This was in spite of the fact that plasmas continued to hold an image quality advantage, but as the president of Chunghwa Picture Tubes noted after shutting down their plasma production line, "Globally, so many companies, so many investments, so many people have been working in this area, on this product. So they can improve so quickly." [14]

When the sales figures for the 2007 Christmas season were finally tallied, pundits were surprised to find that LCDs had not only outsold plasma, but also outsold CRTs during the same period. [17] This evolution drove competing large-screen systems from the market almost overnight. Plasma had overtaken rear-projection systems in 2005. [18] The same was true for CRTs, which lasted only a few months longer; Sony ended sales of their famous Trinitron in most markets in 2007, and shut down the final plant in March 2008. [19] The February 2009 announcement that Pioneer Electronics was ending production of the plasma screens was widely considered the tipping point in that technology's history as well. [20]

LCD's dominance in the television market accelerated rapidly. [14] It was the only technology that could scale both up and down in size, covering both the high-end market for large screens in the 40 to 50" class, as well as customers looking to replace their existing smaller CRT sets in the 14 to 30" range. Building across these wide scales quickly pushed the prices down across the board. [17]

In 2008, LCD TV shipments were up 33 percent year-on-year compared to 2007 to 105 million units. [21] In 2009, LCD TV shipments raised to 146 million units (69% from the total of 211 million TV shipments). [22] In 2010, LCD TV shipments reached 187.9 million units (from an estimated total of 247 million TV shipments). [23] [24]

Current sixth-generation panels by major manufacturers such as Sony , Sharp Corporation , LG Display , Panasonic and Samsung have announced larger sized models:

  • In October 2004, Sharp announced the successful manufacture of a 65" panel.

  • In March 2005, Samsung announced an 82" LCD panel. [25]

  • In August 2006, LG Display Consumer Electronics announced a 100" LCD television [26]

  • In January 2007, Sharp displayed a 108" LCD panel under the AQUOS brand name at CES in Las Vegas. [27]

Recent research [ edit ]

Some manufacturers are also experimenting with extending color reproduction of LCD televisions. Although current LCD panels are able to deliver all sRGB colors using an appropriate combination of backlight's spectrum and optical filters, manufacturers want to display even more colors. One of the approaches is to use a fourth, or even fifth and sixth color in the optical color filter array. Another approach is to use two sets of suitably narrowband backlights (eg LEDs ), with slightly differing colors, in combination with broadband optical filters in the panel, and alternating backlights each consecutive frame. Fully using the extended color gamut will naturally require an appropriately captured material and some modifications to the distribution channel. Otherwise, the only use of the extra colors would be to let the looker boost the color saturation of the TV picture beyond what was intended by the producer, but avoiding the otherwise unavoidable loss of detail ("burnout") in saturated areas.

Competing systems [ edit ]

In spite of LCD's current dominance of the television field, there are several other technologies being developed that address its shortcomings. Whereas LCDs produce an image by selectively blocking a backlight OLED , FED and SED all produce light directly on the front face of the display. In comparison to LCDs, all of these technologies offer better viewing angles, much higher brightness and contrast ratio (as much as 5,000,000:1), and better color saturation and accuracy, and use less power. In theory, they are less complex and less expensive to build.

Actually manufacturing these screens has proved more difficult than originally imagined. Sony abandoned their FED project in March 2009, [28] but continue work on their OLED sets. Canon continues development of their SED technology, but announced that they will not attempt to introduce sets to market for the foreseeable future. [29]

Samsung has been displaying OLED sets at 14.1, 31 and 40 inch sizes for some time, and at the SID 2009 trade show in San Antonio they announced that the 14.1 and 31 inch sets are "production ready". [30]

Environmental effects [ edit ]

See also: Electronic waste

The production of LCD screens uses nitrogen trifluoride (NF 3 ) as an etching fluid during the production of the thin-film components. NF 3 is a potent greenhouse gas , and its relatively long half-life may make it a potentially harmful contributor to global warming . A report in Geophysical Research Letters suggested that its effects were theoretically much greater than better-known sources of greenhouse gasses like carbon dioxide . As NF 3 was not in widespread use at the time, it was not made part of the Kyoto Protocols and has been deemed "the missing greenhouse gas". [31]

Critics of the report point out that it assumes that all of the NF 3 produced would be released to the atmosphere. In reality, the vast majority of NF 3 is broken down during the cleaning processes; two earlier studies found that only 2 to 3% of the gas escapes destruction after its use. [32] Furthermore, the report failed to compare NF 3 's effects with what it replaced, perfluorocarbon , another powerful greenhouse gas, of which anywhere from 30 to 70% escapes to the atmosphere in typical use. [32]