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Yuav Ua Li Cas Ncig Lub Xim Qhov Ncauj Ntawm Lub Automotive TFT-LCD Vaj Huam Sib Luag

Yuav Ua Li Cas Ncig Lub Xim Qhov Ncauj Ntawm Lub Automotive TFT-LCD Vaj Huam Sib Luag

Apr 21, 2017

Qhov kev thov rau gamma correction stems los ntawm tus tsim ntawm CRT TV saib. Lub CRT siv ib txoj hlua hluav taws xob zom zaws kom pom lub teeb ntim tom qab ntawm lub qhov rooj hauv ntej. Qhov siv daim phiaj tswj kev tswj hluav taws xob yog tswj raws qhov kev siv luminous thiab ua raws li txoj cai ntawm lub ntiajteb sab nrauv: luminous siv = Lub gamma-lub sij hawm sab ntawm kev tswj qhov hluav taws xob. Txoj kev tswjfwm no muaj ib qho tsis muaj teebmeem tsis muaj teebmeem. Qhov cim npe ntawm cov CRT yog li ntawm 2. 2. Ntawm qhov tod tes, qhov muag tib neeg muaj ib qho lus teb rov qab, uas yog ib qho tseem ceeb rau cov kev hloov hauv qhov tsaus ntuj nti ntawm qhov grey. Yog li, thiaj li ua kom tiav qhov duab pom qhov tob ntawm qhov grey nyob hauv tib neeg qhov muag, peb yuav tsum txhim kho cov xim liab, ntsuab thiab xiav ua ntej hloov duab. Lub tsev kawm ntawv tau ua nyob rau hauv qhov video source system, xws li lub koob yees duab broadcast TV.

Tsab ntawv xov xwm no piav qhia txog kev ua kom muaj kev sib raug zoo thiab cov xim xim ntawm lub tsheb TFT-LCD vaj huam sib luag ntawm gamma Correction (los yog gamma calibration). Peb mam li sib tham yuav ua li cas siv lub 14-channel programable gamma tsis ua kom qhov gamma teb ntawm lub LCD vaj huam sib luag thiab qhia peb yam piv txwv ntawm siab, nominal, thiab qis gamma nqis.

Qhov tso tawm qhov hluav taws xob ntawm qhov koob yees duab tsim yog proportional to luminous siv, uas sib npaug 1/2 ntawm cov luminous siv. 5 Zaug Square (0.) 4 Zaug Square. Vim tias ib qho me me loj dua 1 ntawm gamma tus nqi txaus siab, txoj cai tshaj tawm siv feem ntau siv 0. Gamma tus nqi 5 ua rau lub zog gamma nqi ntawm 1. 25. Daim duab 1 qhia tau hais tias lub koob yees duab built-in gamma teb yog qhov rov qab ntawm qhov CRT cov lus teb, yog li tsis muaj ntxiv qhov system gamma kho kom raug. Txawm li cas los xij, lub teeb liab TFT-LCD yuav tsum muab kho kom haum rau lub koob yees duab gamma tuning, uas yog pib teeb tsa rau CRT saib

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Daim duab 1. Gamma nqi ntawm cov kab CRT

Automotive LCD vaj huam sib luag Gamma Calibration

Lub vaj huam sib luag hauv TFT-LCD yog ntau thiab ntau dua nyob rau hauv lub tshuab hluav taws xob ua ke, cov ntaub ntawv lom zem thiab cov khoom ontology navigation thiab qhov Advanced Driving Assistive System (ADAS) ntsej muag tsom iav. Hloov siv cov phom fais fab thiab fluorescent txheej kom tsim cov luminous siv, lawv tswj qhov kev xa tawm ntawm "backlighting" los ntawm cov pixel los ntawm exerting ib voltage ntawm lub LCD pixel. Kev siv lub teeb cathode fluorescent teeb (CCFL) lossis lub teeb-emitting diode (LED) arrays muab "backlight". Tus voltage uas tau thov kom muaj qhov pixel LCD yuav tswj tus nqi ntawm lub nrig qaum xa mus rau pem hauv ntej kom me nyuam tus duab uas kis, uas txhais cov kev xa mus rau TFT-LCD.

Lub gamma ntawm TFT-LCD tus nqi txawv ntawm CRT, tab sis nws muaj lus teb me ntsis. Lub gamma calibration ntawm lub cev broadcasting yog kwv nyob rau hauv lub teeb liab kis kab ke los tiv thaiv cov CRT gamma teb, uas muab cov lus teb rov qab ntawm tib neeg qhov muag. Yog li no, nws yuav tsum raug hla mus rau gamma kho ua ntej lub teeb liab siv rau lub vaj huam sib luag TFT-LCD. Tus ntsuas TFT-LCD gamma yog tsim nyog kom ua raws li gamma correction ntawm CRT tus saib xyuas. Lub tswv yim video input yog numeric thiab gamma kho lus code yog siv rau hom kev hloov digital (DAC) los ua kom pom cov voltages thiab siv pixels. Cov cim thiav gamma kho lus pab cov vaj huam sib luag rau lub tshuab hluav taws xob kom pom cov kev cai tsim kho kom pom cov teebmeem. Lub kaw lus muaj peev xwm khaws ntau yam gamma kho qhov teeb meem rau kev sib txawv me ntsis hauv lub teeb meem. Xam 2 qhia qhov normalized gamma kho lus rau lub vaj huam sib luag TFT-LCD siv lub system gamma nqi 1.

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Daim duab 2. Gamma tus nqi rau LCD qhov system

Cov ntaub ntawv ntawm digital video, feem ntau low-voltage differential signals (LVDS), yuav tsum tau hloov dua siab tshiab siv DAC los tsim cov analog voltages rau pixels. Lub plhaub taum nonecotse DAC nyob rau ntawm qhov chaw / kem tsav ntawm lub vaj huam sib luag yog siv rau gamma correction (txhob txwm tsis muaj tseeb). Lub chaw khiav DAC txiav txim tias muaj pes tsawg tus kauj ruam uas muaj peev xwm ua tau sib npaug ntawm pixels (xws li 8-ntsis DAC tuaj yeem ua 28 lossis 256 grayscale). Daim duab 3 qhia tau hais tias qhov kev hloov ntawm kev hloov ntawm cov grey theem ntawm txhua cov kauj ruam ntawm voltage, thiab yog qhov tseem ceeb ntawm gamma lo lus teb ntawm lub vaj huam sib luag (kev xa xov hluav taws xob lossis VT nkhaus) thiab qhov muag teb.

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Xam phaj 3. Kev sib piv ntawm qhov sib txawv ntawm qhov sib txawv ntawm cov lus teb txawv gamma

Cov cuab yeej nonlinear ntawm gamma kho tau tshwm sim hauv cov duab cov ntaub duab nrog cov zauv uas tsis tshua sib luag, thiab cov duab cov ntaub ntawv uas muaj cov qib siab ci ntsa iab yog compressed nrog me me los yog tsis muaj compression. Tsawg theem compression ua rau cov duab cov ntaub ntawv hauv "tsaus nti" rau "ib tsos tsaus tsawv" ntau qhov muag-ntes, thiab tib neeg lub qhov muag yog ntau dua susceptible detection. Qhov no pab tau qhov duab tob. Ua ib qho txiaj ntsim ntxiv, qhov kev sib txuam thiab kev tsis muaj cuabyeej yuav ua rau cov khoom poob ntawm qhov luminance encoding (piv txwv, ib yam tsis muaj teebmeem ntawm 8 yam khoom, thiab ib kab lus ntawm 12 losis 14 khoom). Tsis tas li ntawd, compression yuav pab txo qhov yuav ua rau cov teebmeem video nrov.

Programmable Gamma Buffers

Txhim kho lub gamma ntawm LCD vaj huam sib luag rau hauv qhov kev hloov VT hloov, lub hauv paus (sab) tsav DAC ntawm lub vaj huam sib luag siv tau ntau yam kev siv voltages uas siv rau ntau qhov chaw sib cuag. Cov kev taw qhia no yuam kom txhua DAC muaj qhov laj thawj zoo tsis muaj kev ua haujlwm. Qhov siv hluav taws xob feem ntau yog muab los ntawm gamma tsis IC, uas feem ntau yog tus neeg ua haujlwm kom tsis txhob muaj peev xwm ua kom muaj qhov sib npaug ntawm DAC mus rau DAC. Lub gamma ntab IC yuav ua tau zoo li qub los yog lub program paub. The Intersil ISL76534 yog ib qho khoom siv uas yuav siv tau rau cov tshuab hluav taws xob LCD, los ntawm 14-channel programmatic gamma buffer raws I2C thiab VCOM channel, ob qho tag nrho yog 10 khoom ntawm kev daws teeb meem. Cov cuab yeej muab tau qhov tseeb thiab ruaj khov DC reference voltage rau lub tsheb npav TFT-LCD qhov tsav. Daim duab 4 qhia tau hais tias daim duab yooj yim ntawm TFT-LCD vaj huam sib luag zog.

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Daim Duab 4. Yooj Yim Lawm Cov Vaj Huam Sib Luag Dua

Los ntawm kev tswj cov DAC cov ntsiab lus, automotive LCD cov chaw tsim tshuaj paus yuav nplua-tune cov voltage los ntxiv kho lossis ntsuas cov vaj huam sib luag tus nonlinear Gamma lo lus teb (tseem hu ua gamma calibration). Qhov no yuav pab kom muaj tsheb nqaj hlau kev lag luam hauv tshuab hluav taws xob ua kom pom tseeb tias txhua lub iPad panels nyob rau hauv ib qho ntawm nws cov qauv muaj ib cov lus zoo ib yam li gamma. Qhov no txhais tau hais tias qhov sib txawv ntawm qhov pom tau qhov teeb meem tshwm sim los ntawm cov qauv siv LCD thiab lwm yam tseem ceeb, yog li cov tsheb nqaj hlau cov tshuab LCD yuav ua tau kom muaj ntau yam zoo thiab pom cov khoom muag. Cov neeg tau txais txiaj ntsig tuaj yeem lees paub tias lub tsheb ntawm lawv lub tsheb yuav muaj tib lub qhov muag pom ntawm cov zaub uas lawv pom ntawm kev xeem.

Thaum kawg, lub chaw tsim khoom lag luam txiav txim siab yuav ua li cas thiaj ntsuas tau gamma lo lus teb, xws li Gamma = 2. 2, γ = 2. 0, γ = 1. 8, los sis ib qho kev sib txawv ntawm gamma qhov tseem ceeb raws li qhov kev xav tau, Kev pom nyhuv. Nws yog qhov zoo tshaj plaws tias gamma yam ntxwv yog yooj yim los hloov nrog lub kaum sab xis pom thiab txawv lub teeb meem me me, qhov no thaum yuav khoom ib lub tsheb yuav tsum sib piv cov zaub nyob rau hauv lub teeb thiab lub teeb uas tsis tshua muaj siab nyob rau hauv qhov kev siv ntawm cov zaub, los txiav txim siab seb tus saib Duab yog txaus siab.

Image sib piv ntawm txawv gamma qhov tseem ceeb

Daim duab 5 sib piv cov teeb meem ntawm cov duab qub uas muaj ntau yam sib txawv gamma qhov tseem ceeb, thiab nws yog qhov yooj yim pom qhov txawv. Intermediate image (daim duab 5B) yog ib qho tseem ceeb (primitive) gamma nqi (xws li Γ = 2.) 2, duab saum toj kawg nkaus (Daim duab 5A) siab tshaj tus nqi nominal, hauv qab duab (Daim Duab 5C) Me Yu Biao nqi . Hauv qab duab poob zoo ib yam nrog tsaus xim, thiab ua rau me ntsis ntxig. Cov duab saum toj kawg nkaus yog qhov loj, tiam sis qhov tsaus ntuj zuag qhia tag nrho yog ntau tshaj.

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Daim duab 5A. Piv txwv ntawm gamma tus nqi duab

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Daim duab 5B. Piv txwv ntawm nominal gamma value duab

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Xam 5C. Piv txwv ntawm cov duab tsawg tsawg gamma

Gamma tus nqi thiab automotive infotainment zaub chaw

Automotive LCD vaj huam sib luag muaj ib qhov dub-Bai Duan point qib txiav txim siab los ntawm kev ua tiav ntawm qhov chaw tsav tsheb. Txawm li cas los xij, lub teeb liab yuav muab kho rau digitally thaum ua cov ntaub ntawv video. Xwb, koj tuaj yeem hloov qhov kev ci ntsa iab los ntawm kev kho cov teeb ci ntsa iab ntawm lub vaj huam sib luag hauv LCD, uas ntxiv lwm qhov kev ua tau zoo. Kev tswj cov cuab yeej yog feem ntau kho rau kev ci ntsa iab thiab qhov sib txawv, nruab hnub, thiab hmo ntuj.

Programmable gamma buffers Yooj yim rau kev ua hauj lwm ntawm kev ntsuam xyuas thiab teeb qhov kev hloov cov kev ua haujlwm, xws li xa mus rau qhov kev lag luam raug tsim ntawm cov khoom tsim tsheb. Cov phiaj xwm gamma no tau muab tso rau hauv EEPROM thiab xa mus rau DAC thaum lub nqi them. Qee cov ntiv taw muaj ntau pawg neeg los tuav ntau cov ntaub ntawv tso tawm (profile) coj los sib txawv hauv cov teeb meem txawv me ntsis, thiab kev cai uas tau txais kev cawmdim thiab muab khaws cia los ntawm tus neeg siv nrog cov cuab yeej tsim nyog. Cov kev tso npe ntawm gamma nqis los ntawm lub khw yog feem ntau txaus kom los siav tshaj plaws kev siv tsheb. Lub cajmeem ua tiav thaum pib teeb, thiab ces cov ntaub ntawv hloov tsis hloov lawm ntshe yog tias koj xav tau zoo-tuning los txhim kho cov teebmeem ntawm koj cov duab.

Xaus

Automotive LCD vaj huam sib luag ua haujlwm siv zog los ua cov duab pom teebmeem ntawm lawv cov duab panels pom los ntawm carmakers thiab cov neeg siv. Qhov no yuav tsum muaj kev ruaj khov gamma tsis siv tus nqi kom paub tseeb tias cov duab xim duab uas tso tawm los ntawm nws lub iPad hauv vaj huam sib luag tau zoo sib xws, ci ntsa iab, thiab xim, tsis txawv raws li cov lus. Lub hom phiaj no tau ua tiav kev siv cov cuab yeej ua tiav gamma buffers, xws li Intersil ISL76534. Kawm ntxiv txog ISL76534.