Drum OPC wani muhimmin sashe ne na firinta kuma yana ɗaukar toner ko harsashin tawada da firinta ke amfani da shi. Yayin aikin bugu, a hankali ana canjawa da toner zuwa takarda ta hanyar drum na OPC don samar da rubutu ko hotuna. Drum na OPC kuma yana taka rawa wajen watsa bayanan hoto. Lokacin da kwamfuta ke sarrafa na'urar bugawa don bugawa ta hanyar direban bugawa, kwamfutar tana buƙatar canza rubutu da hotuna don buga su zuwa wasu siginar lantarki, waɗanda ake ɗaukar su zuwa ganga mai ɗaukar hoto ta cikin na'urar bugawa sannan ta canza zuwa rubutu ko hotuna masu gani.