Nyob rau hauv lub xyoo pua 21st, lub zog noj tau nce ua rau kev ua tib zoo saib hauv tag nrho tib neeg lub neej. Vim yog qhov kev xav tau yooj yim rau kev teeb pom kev zoo, yuav ua li cas siv ntau lub zog los tsim teeb pom kev zoo dua los ua ib qho loj zog tsav tsheb rau kev tshawb nrhiav tshiab teeb pom kev zoo. Los ntawm thawj lub teeb pom kev zoo rau lub teeb roj teeb, los ntawm cov roj fluorescent rau ntau yam khoom luminescent, LED teeb pom kev siv tshuab tau tawm. Nyob rau hauv hnub no lub zej zog, qhov sib txawv ntawm lub teeb pom kev zoo ntawm ntau yam media li ntxiv txhawb cov tib neeg kev tshawb nrhiav ntawm yuav ua li cas siv ntau high-brightness LEDs rau illumination. Daim ntawv thov LEDs hauv teeb pom kev zoo tuaj yeem nthuav dav heev.
LED theem pib thiab kev ua haujlwm zoo
Ua ntej, cia peb qhia cov qauv txheej txheem thiab kev ua haujlwm zoo ntawm LEDs. Cov qauv ntawm LED yog ib qho khoom siv ntawm cov khoom siv electroluminescent uas muab tso rau hauv ib lub txee khov thiab tom qab ntawd ntim nrog epoxy rev los tiv thaiv cov tub ntxhais. Vim li no, cov LED muaj kev ua tau zoo seismic. Qhov tseem ceeb ntawm lub teeb tawm ntawm lub teeb uas muaj lub teeb emitting yog lub wafer ntawm ib hom p-type semiconductor thiab n-hom semiconductor, thiab ib txoj kab ntawm p-hom semiconductor thiab n-hom semiconductor yog hu ua PN hlav. Hauv qee cov PN cov haujlwm ntawm cov khoom siv ntawm semiconductor, cov haiv neeg qes qe menyuam muaj npe tuaj nrog cov neeg feem coob tuaj yeem tso tawm ntau lub zog hauv daim ntawv ntawm lub teeb, uas ncaj qha mus hloov hluav taws xob mus rau lub teeb zog. PN hlws tsev ntxiv ib qho rov qab, thiab cov neeg tsis tshua muaj neeg tsis tshua muaj kev nyuaj hno, vim li ntawd lawv tsis ua lub teeb. Thaum nws yog nyob rau hauv cov hauj lwm yav pem suab (piv txwv tias, qhov kev taw qhia rau pem hauv ntej yog siv rau ob hnub), thaum tam sim no ntws los ntawm cov anode ntawm LED mus rau cathode, cov khoom siv hluav taws xob semiconductor emits lub teeb ntawm cov xim sib txawv ntawm ultraviolet mus infrared, thiab siv ntawm lub teeb muaj feem xyuam rau qhov tam sim no.
LED teeb pom kev muaj cov nram qab no:
1. Voltage: LED tom qab txoj kev khiav hauj lwm voltage tsawg tsawg, tuaj yeem tsav los ntawm qhov khoom siv hluav taws xob tsawg tsawg, qhov fais fab tuag hluav taws xob txawv nws txawv raws li qhov kawg khoom, yog ib qho khoom siv kuj zoo ib yam, tshwj xeeb tshaj yog tsim rau pej xeem cov chaw.
2. Kev ua haujlwm: Yog tias muaj qhov zoo li qub, qhov kev siv zog yog txo los ntawm 80% piv nrog lub teeb pom kev zoo nrog tib lub teeb pom kev zoo.
3. Siv Qhov Tseeb: Txhua chav nti LED nti yog ib lub xwmfab 3-5 hli, yog li ntawd nws tuaj yeem npaj tau rau ntau yam duab thiab tsim nyog rau ib qho chaw tsis paub meej.
4. Kev Ruaj Ntseg: feem ntau 100,000 xuab moos, qhov teeb meem ntawm lub teeb yog thawj 50%.
5. Lub sij hawm teb: Lub sij hawm teb ntawm lub teeb roj teeb yog millisecond, thiab lub sij hawm teb ntawm lub teeb teeb yog nanosecond.
6. Ib puag ncig cov pa phem: tsis muaj mercury hlau mercury.
7. Xim: LED xim thiab kev ua haujlwm zoo muaj feem xyuam rau cov khoom thiab cov txheej txheem ua cov LEDs. Tam sim no, nws muaj peb theem pib xim liab, ntsuab thiab xiav.
8. Nqe: Piv nrog cov roj teeb, cov nqi ntawm LED dua. Tus nqi ntawm ntau cov LEDs tuaj yeem sib piv tau rau tus nqi ntawm lub teeb hluav taws xob. Txawm li cas los xij, nrog rau kev nce qib ntawm kev siv tshuab, tus nqi / qhov kev sib raug zoo yuav ua kom zoo dua qub.
LED tsav kua
Txij thaum lub advent ntawm LEDs, LEDs tau txais zoo heev. LED tsav tsheb thiab tsav cov txheej txheem lossi tau muab kho rau tsav LEDs ntau nrawm rau tib neeg teeb pom kev zoo. Los ntawm DC / DC switching fais fab tuag rau lub taub roj teeb, nrog rau cov tsav tsheb tsawg thiab LDO rau cov nqi, tib neeg xaiv ntau hom kab hauv ntau daim ntaub ntawv, uas yog qhov chaw kub tshaj plaws hauv kev ua lag luam. Cov teeb ci ntsa iab ntawm cov khoom xa khoom siv yog cov lus qhia txog kev lag luam ntawm LED. Lub lag luam tseem ceeb, cov nram qab no yuav yog rau lub teeb pom kev ntawm cov khoom txawb, qhia txog ntau hom tsav tsheb tsav LED.
1. Step-up DC / DC switching zog mov paub LED tsav tsheb
Cov yam ntxwv tseem ceeb ntawm qhov kev zov me nyuam yog: tsis tshua muaj input voltage, txawm tias tsawg li 0.7V (ib lub xov tooj cua qhuav). Los ntawm kev xav ntawm kev tsim txuj ci tsim ub ua no, cov tshuab ntaus ntawv zoo nkaus li dhau los, kev siv tshuab ntau dua, thiab qhov ua tau zoo dua. Ib daim ntawv thov daim ntawv hloov yog pom hauv daim duab 1.
Daim Duab 1: Cov ntawv xov xwm raug siv rau lub ntsuas LED-tsav DC-UP DC / DC fais fab mov.
Rau hom ntawv no, tus neeg tsav tsheb thaum ntxov tau txais cov tswv yim tam sim no, thiab cov LED tam sim no tau txiav txim siab raws li VFB / Rb. DC / DC tswv yim voltage VFB feem ntau nyob ib ncig ntawm 1.2V, uas txwv kev ntxiv txhim kho ntawm kev ua tau zoo, nws tus kheej DC / Kev ua haujlwm ntawm DC yog li 80%. Nyob rau hauv daim ntawv thov no, qhov ua tau zoo yog txo qis dua. Nrog rau kev txhim kho technology, txo VFB voltage mus rau hauv 0.1V tuaj yeem ua rau kev ua haujlwm tau zoo tshaj 85%, tshwj xeeb yog hauv kev tsav tsheb. 2-3 teeb nyob hauv daim ntawv thov lub xeev. Qhov zoo thiab qhov tsis zoo ntawm txoj haujlwm no yog raws li hauv qab no:
Qhov zoo tshaj plaws: kev paub tab, tus nqi pheej yig, kev ua kom tsis muaj teeb meem zoo siab thiab kev nyab xeeb tshaj plaws ntawm qee cov kev ua hauj lwm tshiab, xws li kev tiv thaiv kev tiv thaiv kab mob siab tshaj tawm hauv daim duab 1, los yog kev sib txuas ntawm cov teeb meem tam sim no. Tshwj xeeb rau cov nraub qaum nrog cov duab loj loj. Vim tias yuav tsum muaj cov LEDs ntau ntxiv kom muaj kev voj voog nrig, ci ntsa iab thiab uniformity yog cov teeb meem uas yuav tsum tau ntsib.
Tsis zoo: Daim ntawv thov ntawm nws tus kheej inductance txwv qhov loj thiab qhov siab ntawm txoj kab, thiab coj teeb meem uas engineers tsis txaus siab rau lub ntsej muag - EMI ua, tshwj xeeb tshaj yog nyob ze ntawm RF qhov, yuav tsum tau ua kev tshwj xeeb rau cuam tshuam, txwv tsis pub nws yuav ua rau RF txais tos. Qhov rhiab heev yog txo, thiab tseem cuam tshuam ntawm lub suab, xws li lub suab tso tawm tam sim no, cuam tshuam nrog lub suab. Ntxiv mus, nyob rau hauv daim ntawv thov no, yog tias ib qho LED tsis ua, tag nrho cov hlua ntawm LEDs yuav ploj, uas yog qhov tshwm sim uas tib neeg tsis xav pom.
2. Kev them nqi hluav taws xob khiav lub hom
Nov yog txoj kev tshiab ntawm kev tsav tsheb. Tsuas pub, lub twj tso kua hluav taws xob muaj peev xwm siv lub lag luam thiab cov oscillator, logic, thiab qhov kev sib piv ntawm qhov kev lag luam los ua kom muaj zog thiab muaj peev xwm khaws tau hluav taws xob. Vim nws txoj haujlwm loj, me me ceramic capacitors (1μF) siv, uas minimizes qhov chaw thiab cov nqi. Lub twj tso kua roj muaj ob hom kev khiav lag luam, qhov sib xyaw thiab qhov ntsuas tam sim no.
1) Ntev voltage hom them twj. Shengbang Microelectronics 'SGM3110 yog lub twj tso tawm nrog qhov kev ntsuas hluav taws xob. Vim cov kev khiav hauj lwm yam ntxwv ntawm qhov kev ntsuas hluav taws xob li niaj zaus, nws muaj lub siab hloov ntau zaus thiab lub caij nyoog loj heev. Vim li no, cov engineers xav tau kev saib xyuas hauv PCB kev teeb tsa. Nws yog yuav tsum tau hais tias tus capacitor peripheral yuav nyob ze li qhov ua tau kom ntaus nws tus kheej. Lub thaiv hluav taws xob yuav tsum yog luv li sai tau. Lub PCB peripheral yuav tsum loj li sai tau. Tus capacitor peripheral yuav tsum tau ncaj qha mus rau hauv av ntawm SGM3110. Yog tias qhov thaiv tsis tsawg, nws tuaj yeem hla dhau PCB loj loj. Thiab ntau yam kev vias rau qhov zoo grounding.
Kev ua haujlwm tshaj tawm txoj haujlwm: η = Iout * Vout / Iin * Vin
Txij li thaum lub ntaus nws tus kheej tau switching losses thiab capacitor to taub, qhov tseeb efficiency yog qis dua tus nqi no, uas yog muaj feem xyuam rau qhov chaw tsim khoom siv tshuab. Qhov zoo ntawm kev siv cov qauv tsav no yog tias nws ua kom yooj yim to taub cov kab ntawm cov npoo thiab txo nqi khoom. Tshwj xeeb tshaj yog nyob rau hauv cov ntaub ntawv ntawm me me-ntxaij, 1-2 LEDs yog siv raws li cov ntaub npog rov qab; los yog siv ua drives kom cuag tau 250mA tam sim no tso tawm hauv 100mS; los yog ib qho yooj yim DC / DC 5V boost simplified version tsis txhawb inductive DC / DC boost, txo cov nqi thiab khoom EMI teeb meem. Qhov tsis zoo yog tias tsuas muaj ob qho yooj yim ua ob hom kev lag luam, qhov ua tau tsawg dua, feem ntau ntawm cov sij hawm ua haujlwm yog qis dua 70%, qhov kev siv ntawm cov khoom siv tsawg dua, thiab feem ntau ntawm nws yog noj nyob rau hauv lub sijhawm tam sim no. Thaum tsav tsheb ntau ntau, cov teeb ci ntsa nrig yog nyob ntawm seb qhov teeb meem ntawm cov LEDs thiab tam sim no tsis muaj teeb meem.
2) Lub sijhawm tam sim no lub twj tso dag. Yuav kom ntxiv txhim kho qhov kev ntsuas ntawm LED tsav tsheb, Shengbang Microelectronics qhia txog qhov tam sim no hom twj ntawm lub SGM3123 nrog 1X, 1.5X thiab 2X boost nyob rau hauv lub quarter thib ob ntawm xyoo 2008. Rau qhov tam sim no lub hom tswb twj, mus txog hauv Internal Logic tswj siv los ua kom sib koom tau rau txhua tus LED, thiaj li hais tias qhov ci ntsa iab ntawm cov LEDs khaws cia sib npaug, thiab tib lub sijhawm, kev tsav tsheb ntawm cov LED zoo dua li qhov ua tau.
Nyob rau hauv daim ntawv thov no, lub teeb ci ci ntawm cov LED yog tswj los ntawm cov cuab yeej tswj kev tswj iav tam sim no, cov LED tam sim no ntawm txhua channel tsis pub tshaj 2%, thiab cov 1X, 1.5X boost hom ua qhov kev tsav tsheb uas tsav lub ntsuas kom muaj zog, thiab LED yog loj. Nyob rau qee lub sij hawm ua hauj lwm, kev tsav tsheb yuav tuaj yeem lav tau siab tshaj 80%. Cov kab ntawv sau tau raug qhia hauv daim duab 2.
Daim Duab 2: Cov ntawv xov xwm raug rau hom tshiab tam sim no lub nqi twj SGM3123.
Siv ntau qhov tseem ceeb coj los teeb cov LED tso zis tam sim no: ILED = Muaj pov hwm * Vauv / RIset. Cov tuam txhab sib txawv nyias muaj nyias kev sib tw. Nyob rau tib lub sij hawm raws li kev hloov tshiab ntawm cov twj siv twj, cov tib neeg kuj pom tias nws siv LED tsav tsheb zoo dua DC / DC, txo cov nqi, txo qhov kev tsav tsheb, thiab tsis txhob cuam tshuam rau EMI.
3. Rau txoj kev ua raws li tus nqi thiab kev ua tau zoo, kuj muaj ntau yam kev tsav tsheb xws li cov tsav tsheb tsawg tsawg ntawm LED. Piv rau lub twj tso kua mis ntawm lub hom phiaj tam sim no, tsuas yog lub twj tso kua roj boost tsis tas li, thiab cov khoom siv tam sim no tam sim no tseem zoo li qub. Tus nqi tiv tiag tam sim no lub hom nqi twj tso kua piv kuj raug qis dua. Qhov tsis zoo yog tias txoj kev ntshiab khiav tawm, thaum lub roj teeb voltage tee rau ib tug qis, xws li 3.6V, thaum muaj kev cuam tshuam loj loj: xov tooj txuas nrog kev hu xov tooj los yog thaij duab, MP3 playing music, MP4 playing yeeb yaj kiab, yuav ua rau muaj hluav taws xob hloov, qhov hluav taws xob yuav poob 0.1 ~ 0.2V, tom qab ntawd ces qhov system hluav taws xob yuav poob rau 3.
