PWM dimming yog ib qho tseem ceeb dimming tshuab siv nyob rau hauv LED dimming zog khoom. Nyob rau hauv lub voj voog ntawm lub teeb liab analog, lub ci ci ntawm kev tswj luminaire yog digitally outputted. Txoj kev dimming no muaj ntau yam zoo piv nrog cov tsoos analog teeb liab dimming. Tau kawg, muaj qee yam tsis xws luag hauv qee yam. Qhov zoo thiab qhov tsis zoo yog dab tsi?
Cia thawj saib lub hauv paus ntsiab lus ntawm pwm dimming. Nyob rau hauv qhov tseeb, nyob rau hauv lub tswv yim daim ntawv thov ntawm cov khoom, nws muaj peev xwm to taub hais tias ib tug MOS hloov raj yog kev cob cog rua rau lub load ntawm lub LED. Lub anode ntawm txoj hlua yog powered los ntawm qhov chaw tam sim no. Tom qab ntawd lub teeb liab PWM yog siv rau lub rooj vag ntawm MOS transistor kom hloov cov hlua ntawm LEDs sai sai rau dimming.
Qhov zoo ntawm pwm dimming:
Ua ntej, pwm dimming yog qhov tseeb dimming.
Dimming raug yog ib qho zoo kawg nkaus feature ntawm cov teeb liab dimming ntau, vim pwm dimming siv mem tes waveform signals nrog siab precision.
Thib ob, pwm dimming, tsis muaj xim sib txawv.
Nyob rau hauv tag nrho cov dimming ntau, txij li thaum lub LED tam sim no yog nyob rau ntawm lub siab tshaj plaws tus nqi los yog muab tua, qhov nruab nrab tam sim no ntawm lub LED yog hloov los ntawm kev kho lub pulse lub luag hauj lwm piv, yog li cov tswv yim yuav zam tau cov xim txawv thaum lub sij hawm tam sim no hloov.
Thib peb, pwm dimming, adjustable ntau yam.
PWM dimming zaus feem ntau yog 200 Hz (tsawg zaus dimming) txog 20 kHz lossis ntau dua (siab zaus dimming).
Plaub, pwm dimming, tsis muaj strobe.
Ntev npaum li PWM dimming zaus siab dua 100 Hz, tsis pom kev flickering ntawm LED. Nws tsis hloov cov kev khiav hauj lwm ntawm qhov tam sim no qhov chaw (boost ratio los yog step-down ratio), thiab nws yog tsis yooj yim sua kom overheat. Txawm li cas los xij, PWM mem tes dav dimming kuj muaj teeb meem kom paub txog. Thawj yog qhov kev xaiv ntawm cov mem tes zaus: vim tias LED yog nyob rau hauv lub xeev hloov ceev, yog tias qhov kev khiav hauj lwm zaus tsawg heev, tib neeg lub qhov muag yuav hnov zoo li flicker. Txhawm rau kom siv tag nrho ntawm qhov pom qhov tshwm sim ntawm tib neeg lub qhov muag, nws qhov kev ua haujlwm zaus yuav tsum siab dua 100 Hz, nyiam dua 200 Hz.
Dab tsi yog qhov tsis zoo ntawm pwm dimming?
Lub suab nrov los ntawm dimming yog ib qho. Txawm hais tias nws tsis pom los ntawm tib neeg lub qhov muag saum 200 Hz, nws yog qhov ntau ntawm tib neeg hnov txog 20 kHz. Lub sijhawm no, nws tuaj yeem hnov cov suab ntawm cov lo lo ntxhuav. Muaj ob txoj hauv kev los daws qhov teeb meem no. Ib qho yog txhawm rau nce qhov hloov pauv mus rau saum 20 kHz thiab dhia tawm ntawm tib neeg pob ntseg. Txawm li cas los xij, ntau zaus tuaj yeem ua rau qee qhov teeb meem, vim tias qhov cuam tshuam ntawm ntau yam kab mob parasitic yuav ua rau cov mem tes waveform (pem hauv ntej thiab nram qab ntug) yuav distorted. Qhov no txo qhov tseeb ntawm dimming. Lwm txoj hauv kev yog txhawm rau nrhiav lub suab nrov thiab ua haujlwm. Qhov tseeb, lub suab nrov tseem ceeb yog ceramic capacitor ntawm qhov tso zis, vim hais tias ceramic capacitors feem ntau yog ua los ntawm high dielectric tas li ceramics, uas muaj piezoelectric zog. Mechanical vibration tshwm sim nyob rau hauv qhov kev txiav txim ntawm 200 Hz mem tes. Kev daws yog siv lub tantalum capacitor hloov. Txawm li cas los xij, high-voltage tantalum capacitors yog qhov nyuaj kom tau txais, thiab tus nqi kim heev, uas yuav ua rau qee tus nqi nce.
Txhawm rau ua kom tiav, qhov zoo ntawm pwm dimming yog: daim ntawv thov yooj yim, kev ua haujlwm siab, siab precision, thiab zoo dimming nyhuv. Qhov tsis zoo yog vim tias tus tsav tsheb dav dav LED yog raws li lub hauv paus ntsiab lus ntawm kev hloov hluav taws xob, yog tias PWM dimming zaus nyob nruab nrab ntawm 200 thiab 20 kHz, qhov inductance thiab tso zis capacitance nyob ib ncig ntawm LED dimming fais fab mov yog nquag muaj suab nrov uas yog audible rau. tib neeg pob ntseg. Tsis tas li ntawd, thaum ua PWM dimming, qhov ze dua qhov zaus ntawm qhov hloov kho teeb liab yog rau qhov zaus ntawm LED tsav nti mus rau lub rooj vag tswj teeb liab, qhov cuam tshuam ntawm linear yog qhov tsis zoo.
