Ib lub kua siv lead ua kua yog hom hluav taws xob tsim duab ntawm lub vaj huam sib luag tiaj tiaj. Thawj LCDs, uas tau tawm hauv xyoo 1970, yog cov ntxaij vab tshaus me me siv feem ntau hauv tshuab xam zauv thiab digital watches uas tso tawm cov lej dub ntawm cov keeb kwm dawb. LCDs tuaj yeem pom nyob txhua qhov chaw hauv tsev hluav taws xob hauv tsev, xov tooj ntawm tes, koob yees duab thiab lub computer saib, nrog rau cov saib thiab TV. Niaj hnub no lub xeev-ntawm-lub-kos duab LCD vaj huam sib luag tiaj tus TVs tau hloov ntau cov tsoos bulky CRTs nyob rau hauv cov TVs thiab muaj peev xwm tsim high-txhais xim dluab mus txog 108 nti kab pheeb ces kaum hla lub screen.
History of kua crystals
Cov kua qaub tau pom los ntawm kev sib tsoo hauv xyoo 1888 los ntawm botanist F. Reinitzer los ntawm Austria. Nws pom tias cov roj cholesterol benzoate muaj ob lub ntsiab lus melting, tig mus rau hauv cov kua huab ntawm 145 ° C, thiab ntawm qhov kub siab tshaj 178.5 ° C, cov kua ua pob tshab. Raunrhiav kev piav qhia txog qhov tshwm sim no, nws tau muab nws cov qauv rau tus kws kho mob Otto Lehmann. Siv lub tshuab ntsuas cua nruab nrog cov cua sov, Lehman tau pom tias cov khoom muaj qhov muag pom cov yam ntxwv ntawm qee cov muaju, tab sis tseem yog cov kua, thiab li no lo lus "kua siv lead ua" tau coined.
Lub sijhawm xyoo 1920 thiab 1930s, cov kws tshawb fawb tau kawm txog cov teebmeem ntawm electromagnetic teb ntawm cov kua siv lead ua kua. Nyob rau hauv 1929, Lavxias teb sab physicist Vsevolod Frederiks qhia tau hais tias lawv cov molecules nyob rau hauv ib tug nyias zaj duab xis sandwiched ntawm ob daim hlau hloov lawv cov kev sib raug zoo thaum lub magnetic teb tau thov. Nws yog lub forerunner ntawm niaj hnub voltage kua siv lead ua zaub. Txoj kev txhim kho thev naus laus zis txij li thaum xyoo 1990s tau nrawm heev thiab txuas ntxiv mus.
LCD thev naus laus zis tau hloov kho los ntawm cov xim dub thiab dawb rau cov saib yooj yim thiab lub laij lej rau ntau xim rau cov xov tooj ntawm tes, khoos phis tawj thiab TV. Kev lag luam thoob ntiaj teb LCD tam sim no nce txog $ 100 nphom hauv ib xyoos, nce ntawm $ 60 nphom hauv xyoo 2005 thiab $ 24 nphom hauv xyoo 2003, feem. LCD kev tsim khoom yog thoob ntiaj teb tsom mus rau Far East thiab loj hlob hauv Central thiab Eastern Europe. Cov tuam txhab Asmeskas ua tus thawj coj hauv kev tsim khoom siv tshuab. Lawv cov lus qhia tam sim no yeej muaj kev lag luam thiab qhov no tsis zoo li yuav hloov pauv yav tom ntej.
Physics ntawm cov txheej txheem crystallization
Feem ntau cov kua siv lead ua kua, xws li cholesteryl benzoate, yog tsim los ntawm cov molecules nrog cov pas nrig ntev. Qhov no tshwj xeeb qauv ntawm cov kua moleculescrystals ntawm ob lub lim dej polarizing tuaj yeem tawg los ntawm kev siv hluav taws xob rau cov electrodes, LCD lub caij ua opaque thiab tseem tsaus. Ua li no, ntau yam khoom siv tuaj yeem hloov mus rau lub teeb lossis xim tsaus, yog li tso tawm cov lej lossis cov cim.
Qhov kev sib xyaw ua ke ntawm cov rog txaus nyiam uas muaj nyob nruab nrab ntawm txhua lub molecules txuam nrog cov qauv zoo li tus pas nrig ua rau tsim cov kua siv lead ua kua theem. Txawm li cas los xij, qhov kev cuam tshuam no tsis muaj zog txaus kom cov molecules nyob rau hauv qhov chaw mus tas li. Txij thaum ntawd los, ntau ntau hom kua siv lead ua kua tau raug tshawb pom. Ib txhia ntawm lawv yog teem nyob rau hauv cov khaubncaws sab nraud povtseg, lwm tus nyob rau hauv daim ntawv ntawm ib tug disk los yog daim ntawv kab.
YLCD technology
Lub hauv paus ntsiab lus ua haujlwm ntawm cov kua siv lead ua kua yog ua raws cov khoom ntawm cov khoom siv hluav taws xob hu ua kua muaju, uas ntws zoo li cov kua dej tab sis muaj cov qauv crystalline. Nyob rau hauv crystalline solids, cov constituent hais - atoms los yog molecules - yog nyob rau hauv geometric arrays, thaum nyob rau hauv ib tug dej lub xeev lawv muaj kev ywj pheej mus ncig randomly.
Cov khoom siv ua kua siv lead ua kua muaj cov molecules, feem ntau cov pas nrig-puab, uas teeb tsa hauv ib qho kev taw qhia tab sis tseem tuaj yeem txav mus. Cov kua siv lead ua kua molecules teb rauib qho hluav taws xob hluav taws xob uas hloov lawv txoj kev taw qhia thiab hloov cov yam ntxwv kho qhov muag ntawm cov khoom. Cov cuab yeej no yog siv rau ntawm LCDs.
Ntawm qhov nruab nrab, xws li lub vaj huam sib luag muaj ntau txhiab tus duab ntsiab lus ("pixels"), uas yog tus kheej siv los ntawm qhov hluav taws xob. Lawv nyias nyias, sib dua thiab muaj qhov ua haujlwm qis dua li lwm cov thev naus laus zis thiab zoo tagnrho rau cov khoom siv roj teeb.
Passive Matrix
Muaj ob hom kev qhia: passive thiab nquag matrix. Passive sawv daws yuav tswj los ntawm tsuas yog ob lub electrodes. Lawv yog strips ntawm pob tshab ITO uas tig 90 rau ib leeg. Qhov no tsim tus ntoo khaub lig matrix uas tswj txhua LC cell ntawm tus kheej. Qhov chaw nyob yog ua los ntawm logic thiab tsav tsheb sib cais los ntawm cov LCD. Txij li thaum tsis muaj nqi hauv LC ntawm tes hauv hom kev tswj no, cov kua siv lead ua kua molecules maj mam rov qab mus rau lawv qhov qub qub. Yog li ntawd, txhua lub xov tooj yuav tsum tau saib xyuas ntawm lub sijhawm tsis tu ncua.
Passives muaj lub sijhawm teb ntev thiab tsis haum rau cov ntawv thov hauv TV. Zoo dua, tsis muaj cov tsav tsheb lossis cov khoom siv hloov pauv xws li transistors tau nruab rau ntawm cov iav substrate. Kev poob ntawm qhov ci vim qhov ntxoov ntxoo los ntawm cov ntsiab lus no tsis tshwm sim, yog li kev ua haujlwm ntawm LCDs yog qhov yooj yim heev.
Passive yog siv dav nrog cov lej thiab cov cim rau kev nyeem ntawv me me hauv cov khoom siv xws liLub laij lej, tshuab luam ntawv thiab cov chaw taws teeb tswj, feem ntau yog monochrome lossis tsuas muaj ob peb xim. Passive monochrome thiab cov duab nraaj xim tau siv nyob rau hauv lub laptops thaum ntxov thiab tseem siv los ua lwm txoj hauv kev ua haujlwm matrix.
Active TFT zaub
Acive matrix qhia txhua tus siv ib qho transistor los tsav thiab lub capacitor los khaws cov nqi. Hauv IPS (In Plane Switching) thev naus laus zis, lub hauv paus ntsiab lus ntawm kev ua haujlwm ntawm cov kua siv lead ua kua siv cov qauv tsim qhov twg cov electrodes tsis sib tshooj, tab sis nyob ib sab ntawm ib sab hauv tib lub dav hlau ntawm lub iav substrate. Lub teb hluav taws xob nkag mus rau LC molecules kab rov tav.
Lawv tau ua raws li qhov sib npaug ntawm qhov screen, uas ua rau kom pom lub kaum ntse ntse. Qhov tsis zoo ntawm IPS yog tias txhua lub xov tooj xav tau ob lub transistors. Qhov no txo qhov chaw pob tshab thiab xav tau lub teeb ci dua. VA (Vertical Alignment) thiab MVA (Multi-Domain Vertical Alignment) siv cov kua siv lead ua kua uas zoo tshaj plaws uas sib dhos vertically yam tsis muaj hluav taws xob, uas yog, perpendicular rau qhov screen nto.
Polarized lub teeb tuaj yeem dhau mus tab sis raug thaiv los ntawm pem hauv ntej polarizer. Yog li, lub xov tooj ntawm tes tsis ua kom muaj xim dub. Txij li thaum tag nrho cov molecules, txawm tias cov nyob rau ntawm ntug ntawm lub substrate, yog uniformly vertically aligned, lub resulting dub nqi yog li loj heev nyob rau hauv tag nrho cov ces kaum. Tsis zoo li passive matrixCov kua siv lead ua kua, cov lus qhia matrix muaj lub transistor nyob rau hauv txhua xim liab, ntsuab, thiab xiav sub-pixel uas ua rau lawv nyob rau ntawm qhov xav tau siv kom txog rau thaum kab ntawd tau hais nyob rau hauv kab ntawv txuas ntxiv.
Cell hloov sijhawm
Lub sijhawm teb ntawm cov lus pom ib txwm yog teeb meem loj. Vim yog cov viscosity siab ntawm cov kua siv lead ua kua, LCD hlwb hloov maj mam. Vim yog qhov nrawm nrawm hauv daim duab, qhov no ua rau tsim cov kab txaij. Tsawg viscosity kua siv lead ua kua thiab hloov kho kua siv lead ua cell tswj (overdrive) feem ntau daws cov teeb meem no.
Lub sijhawm teb ntawm cov LCDs niaj hnub tam sim no yog kwv yees li 8ms (lub sijhawm teb ceev tshaj plaws yog 1ms) hloov qhov ci ntawm thaj chaw duab los ntawm 10% mus rau 90%, qhov twg 0% thiab 100% yog qhov ci ntsa iab, ISO 13406 -2 yog qhov sib npaug ntawm lub sijhawm hloov ntawm qhov kaj mus rau qhov tsaus ntuj (los yog vice versa) thiab vice versa. Txawm li cas los xij, vim yog cov txheej txheem hloov pauv asymptotic, lub sijhawm hloov pauv ntawm <3 ms yuav tsum tau zam kom tsis txhob pom cov bands.
Overdrive thev naus laus zis txo lub sijhawm hloov pauv ntawm cov kua siv lead ua kua. Rau lub hom phiaj no, qhov hluav taws xob siab dua yog siv rau ib ntus rau lub LCD cell tshaj qhov tsim nyog rau qhov tseeb qhov ci. Vim lub luv luv voltage surge ntawm cov kua siv lead ua kua, cov inert kua crystals cia li tawg tawm ntawm lawv txoj hauj lwm thiab theem tawm sai dua. Rau qib txheej txheem no, cov duab yuav tsum tau cached. Ua ke nrog tshwj xeeb tsim rau cov nqi sib xwstso saib kev kho, qhov sib thooj voltage qhov siab nyob ntawm gamma thiab yog tswj los ntawm lookup tables los ntawm lub teeb liab processor rau txhua pixel, thiab xam lub sij hawm npaum li cas ntawm cov ntaub ntawv duab.
Lub ntsiab ntawm cov ntsuas ntsuas
Kev sib hloov hauv lub polarization ntawm lub teeb uas ua los ntawm cov kua siv lead ua kua yog lub hauv paus rau kev ua haujlwm ntawm LCD. Muaj ob hom LCDs, Transmissive thiab Reflective:
- Kev hloov pauv.
- Kev sib kis.
Kev xa tawm LCD zaub ua haujlwm. Nyob rau sab laug, lub LCD backlight emits unpolarized lub teeb. Thaum nws dhau los ntawm lub nraub qaum polarizer (ntsug polarizer), lub teeb yuav dhau los ua vertically polarized. Lub teeb no ces hits cov kua siv lead ua kua thiab yuav ntswj lub polarization yog qhib. Yog li ntawd, thaum lub teeb vertically polarized dhau los ntawm ON kua siv lead ua ntu, nws dhau los ua kab rov tav polarized.
Tom ntej - pem hauv ntej polarizer yuav thaiv kab rov tav polarized teeb. Yog li, ntu no yuav tshwm sim tsaus rau tus neeg soj ntsuam. Yog tias cov kua siv lead ua ntu raug muab tua, nws yuav tsis hloov lub polarization ntawm lub teeb, yog li nws yuav nyob twj ywm vertically polarized. Yog li, pem hauv ntej polarizer kis lub teeb no. Cov lus qhia no, feem ntau hu ua backlit LCDs, siv lub teeb ambient raws li lawv qhov chaw:
- Clock.
- YReflective LCD.
- Feem ntau cov tshuab xam zauv siv hom zaub no.
ntu zoo thiab tsis zoo
Daim duab zoo yog tsim los ntawm cov pixels tsaus lossis ntu ntawm keeb kwm dawb. Nyob rau hauv lawv, cov polarizers yog perpendicular rau ib leeg. Qhov no txhais tau tias yog tias pem hauv ntej polarizer yog ntsug, tom qab polarizer yuav yog kab rov tav. Yog li OFF thiab keeb kwm yav dhau yuav cia lub teeb hla, thiab ON yuav thaiv nws. Cov lus qhia no feem ntau yog siv rau hauv cov ntawv thov uas muaj lub teeb nyob ib puag ncig.
Nws tseem muaj peev xwm tsim cov khoom hauv lub xeev thiab cov kua siv lead ua kua nrog cov xim sib txawv. Daim duab tsis zoo yog tsim los ntawm lub teeb pixels lossis ntu ntawm qhov tsaus ntuj. Nyob rau hauv lawv, pem hauv ntej thiab nram qab polarizers yog ua ke. Qhov no txhais tau tias yog pem hauv ntej polarizer yog ntsug, lub rear kuj yuav ntsug thiab vice versa.
Yog li qhov OFF ntu thiab keeb kwm yav dhau thaiv lub teeb, thiab ntu ON cia lub teeb hla, tsim lub teeb pom kev tawm tsam tom qab tsaus. Backlit LCDs feem ntau siv hom no, uas yog siv qhov chaw teeb pom kev zoo tsis muaj zog. Nws kuj muaj peev xwm tsim cov xim tom qab sib txawv.
Display nco RAM
DD yog lub cim xeeb uas khaws cov cim tso rau ntawm qhov screen. Txhawm rau tso tawm 2 kab ntawm 16 tus cim, chaw nyob raug txhais raws li hauv qab no:
| Line | Visible | Tsis pom |
| Top | 00H 0FH | 10H 27H |
| qis | 40H - 4FH | 50H 67H |
Nws tso cai rau koj los tsim ntau tshaj 8 tus cim lossis 5x7 cim. Thaum cov cim tshiab raug thauj mus rau hauv lub cim xeeb, lawv tuaj yeem nkag tau zoo li lawv yog cov cim ib txwm khaws cia hauv ROM. CG RAM siv 8-ntsis cov lus dav, tab sis tsuas yog 5 qhov tseem ceeb me ntsis tshwm sim ntawm LCD.
Yog li D4 yog qhov taw qhia sab laug thiab D0 yog tus ncej ntawm sab xis. Piv txwv li, loading RAM byte CG ntawm 1Fh hu tag nrho cov dots ntawm kab no.
Bit mode control
Muaj ob hom zaub muaj: 4-ntsis thiab 8-ntsis. Hauv 8-ntsis hom, cov ntaub ntawv raug xa mus rau cov zaub los ntawm tus pins D0 rau D7. Txoj hlua RS yog teem rau 0 lossis 1, nyob ntawm seb koj xav xa cov lus txib lossis cov ntaub ntawv. R / W kab kuj yuav tsum tau teem rau 0 los qhia cov zaub yuav tsum tau sau. Nws tseem yuav xa cov mem tes tsawg kawg yog 450 ns los nkag E los qhia tias cov ntaub ntawv siv tau muaj nyob ntawm tus pins D0 rau D7.
Cov zaub yuav nyeem cov ntaub ntawv ntawm qhov poob ntawm qhov kev tawm tswv yim no. Yog xav tau kev nyeem ntawv, cov txheej txheem yog tib yam, tab sis lub sij hawm no R / W kab yog teem rau 1 thov kom nyeem. Cov ntaub ntawv yuav siv tau ntawm kab D0-D7 ntawm txoj kab siab.
4-ntsis hom. Qee zaum, nws yuav tsim nyog los txo cov xov hlau uas siv los tsav cov zaub, xws li thaum lub microcontroller muaj I / O pins tsawg heev. Hauv qhov no, 4-ntsis LCD hom tuaj yeem siv tau. Nyob rau hauv hom no, mus rau kiscov ntaub ntawv thiab nyeem lawv, tsuas yog 4 qhov tseem ceeb tshaj plaws (D4 txog D7) ntawm cov zaub yog siv.
4 cov khoom tseem ceeb (D0 txog D3) txuas rau hauv av. Cov ntaub ntawv yog sau los yog nyeem los ntawm kev xa plaub qhov tseem ceeb tshaj plaws nyob rau hauv ib ntus, ua raws li plaub yam tsawg kawg nkaus. Lub mem tes zoo ntawm yam tsawg kawg yog 450 ns yuav tsum raug xa mus rau ntawm kab E txhawm rau kuaj txhua nibble.
Hauv ob hom, tom qab txhua qhov kev ua ntawm cov zaub, koj tuaj yeem paub tseeb tias nws tuaj yeem ua cov ntaub ntawv hauv qab no. Txhawm rau ua qhov no, koj yuav tsum tau thov kev nyeem hauv hom lus txib thiab tshawb xyuas tus chij Busy BF. Thaum BF=0, cov zaub npaj tau txais cov lus txib tshiab lossis cov ntaub ntawv.
cov khoom siv hluav taws xob digital
Digital kua siv lead ua ntsuas ntsuas rau cov neeg ntsuas muaj ob daim iav nyias, ntawm cov ntsej muag uas nyias nyias tau siv. Thaum lub iav pom los ntawm sab xis, lossis yuav luag ntawm lub kaum sab xis, cov lem no tsis pom. Txawm li cas los xij, ntawm qee qhov kev pom, lawv pom.
Daim duab hluav taws xob hluav taws xob.
Tus ntsuas tau piav qhia ntawm no muaj cov duab plaub oscillator uas tsim kom muaj qhov sib luag AC voltage yam tsis muaj DC tivthaiv. Feem ntau cov tshuab hluav taws xob logic tsis muaj peev xwm tsim tau lub voj voog square, lawv tsim cov square waveforms uas nws lub luag haujlwm hloov pauv ntawm 50%. 4047 siv nyob rau hauv lub tester muaj ib tug binary scalar tso zis uas guarantees symmetry. Ntau zausoscillator yog hais txog 1 kHz.
Nws tuaj yeem siv tau los ntawm 3-9V cov khoom siv. Nws qhia tau hais tias ntawm qhov voltage qhov ntsuas qhov ntsuas hluav taws xob ua kua siv lead ua ua haujlwm txaus siab, thiab tseem muaj kev sib raug zoo ntawm cov qib voltage thiab lub kaum sab xis ntawm cov zaub kom pom tseeb. Tus tester kos tsis ntau tshaj 1 mA.
Qhov ntsuas hluav taws xob yuav tsum ib txwm txuas ntawm lub davhlau ya nyob twg, piv txwv li lub dav hlau nram qab, thiab ib qho ntawm ntu. Yog tias nws tsis paub tias lub davhlau ya nyob twg yog lub nraub qaum, ces txuas ib qho kev sojntsuam ntawm tus ntsuas mus rau ntu thiab lwm qhov kev sojntsuam rau tag nrho lwm cov terminals kom txog rau thaum ntu pom.
