LED PWM dimming
PWM dimming fasaha ce ta yau da kullun da aka yi amfani da ita a cikin samfuran wutar lantarki na LED. A cikin da'irar siginar analog, ana fitar da hasken wutar lantarki ta hanyar lambobi. Wannan hanyar dimming tana da fa'idodi da yawa idan aka kwatanta da na gargajiya na siginar analog dimming. Tabbas, akwai wasu nakasu a wasu bangarorin. Menene fa'ida da rashin amfani?
Bari mu fara duba ainihin ƙa'idar pwm dimming. A gaskiya ma, a cikin aikace-aikacen aikace-aikacen samfurin, ana iya fahimtar cewa an haɗa bututun sauya MOS a cikin nauyin LED. An yi amfani da anode na kirtani ta hanyar ci gaba na yanzu. Ana amfani da siginar PWM a ƙofar MOS transistor don sauya igiyoyin LED da sauri don ragewa.
Fa'idodin pwm dimming:
Na farko, pwm dimming yana dimming daidai.
Dimming daidaito alama ce ta ban mamaki na raguwar siginar dijital gama gari, saboda pwm dimming yana amfani da siginar bugun bugun jini tare da madaidaici.
Na biyu, pwm dimming, babu bambancin launi.
A cikin duka kewayon dimming, tun da LED halin yanzu yana ko dai a matsakaicin darajar ko kuma an kashe shi, ana canza matsakaicin halin yanzu na LED ta hanyar daidaita yanayin aikin bugun jini, don haka makircin zai iya guje wa bambancin launi yayin canjin na yanzu.
Na uku, pwm dimming, daidaitacce kewayon.
Mitar dimming PWM gabaɗaya ita ce 200 Hz (ƙananan ƙarancin mitar) zuwa 20 kHz ko fiye (maɗaukakin mitar mitar).
Na hudu, pwm dimming, babu tabo.
Muddin mitar dimming PWM ya fi 100 Hz, ba a lura da firar LED ɗin ba. Ba ya canza yanayin aiki na madaidaicin tushen yanzu (rabo na haɓaka ko matakin ƙasa), kuma ba shi yiwuwa a yi zafi sosai. Koyaya, dimming na PWM bugun bugun jini shima yana da matsalolin da yakamata a sani. Na farko shi ne zabin mitar bugun jini: saboda LED yana cikin saurin sauyawa, idan mitar aiki ta yi ƙasa sosai, idon ɗan adam zai ji daɗi. Domin yin cikakken amfani da abin da ya saura na gani na ido na mutum, ya kamata mitar aikinsa ya fi 100 Hz, zai fi dacewa 200 Hz.
Menene rashin amfanin pwm dimming?
Hayaniyar dimming daya ce. Ko da yake idon ɗan adam ba zai iya gano shi sama da 200 Hz, shi ne kewayon jin ɗan adam har zuwa 20 kHz. A wannan lokacin, ana iya jin sautin siliki. Akwai hanyoyi guda biyu don magance wannan matsalar. Daya shine ƙara mitar sauyawa zuwa sama da 20 kHz kuma tsalle daga cikin kunnen ɗan adam. Duk da haka, yawan mitoci na iya haifar da wasu matsaloli, saboda tasirin sifofin parasitic daban-daban zai sa yanayin bugun bugun jini (gefuna na gaba da na baya) ya lalace. Wannan yana rage daidaiton dimming. Wata hanya kuma ita ce gano na'urar mai sauti da kuma sarrafa ta. A gaskiya ma, babban na'urar sauti ita ce yumbu capacitor a fitarwa, saboda yumbu capacitors yawanci ana yin su ne da manyan yumbu masu mahimmanci na dielectric, wanda ke da kaddarorin piezoelectric. Jijjiga injina yana faruwa ƙarƙashin aikin bugun bugun 200 Hz. Maganin shine a yi amfani da capacitor tantalum maimakon. Duk da haka, babban ƙarfin wutar lantarki tantalum capacitors yana da wuya a samu, kuma farashin yana da tsada sosai, wanda zai kara wasu farashi.
Don taƙaitawa, fa'idodin pwm dimming sune: aikace-aikacen mai sauƙi, ingantaccen inganci, babban madaidaici, da tasirin dimming mai kyau. Rashin hasara shine tunda babban direban LED ya dogara ne akan ka'idar canza wutar lantarki, idan mitar dimming PWM ta kasance tsakanin 200 da 20 kHz, ƙarfin inductance da ƙarfin fitarwa a kusa da samar da wutar lantarki na LED suna da haɗari ga hayaniya da ake iya ji kunnen mutum. Bugu da kari, lokacin yin dimming PWM, mafi kusancin mitar siginar daidaitawa shine mitar guntuwar direban LED zuwa siginar sarrafa ƙofar, mafi munin tasirin layin shine.