22 2-372-37Technology > Image Formation System > Controls > Drum UnitTechnology > Image Formation System > Controls > Drum UnitControlsDrum UnitThe drum unit mainly consists of the photosensitive drum, primary charging roller, brush roller,cleaning blade, and waste toner feed screw, and is driven by the main motor (M1).Cleaning blade in contact with the photosensitive drum scrapes off the residual toner on itssurface without being transferred to a paper. The residual toner scraped off by the cleaningblade is fed from the toner ejection part into the waste toner box by the waste toner feedscrew. The primary charging roller is cleaned by the brush roller in contact with it.Photosensitive drumCleaning BladePrimary charging rollerWaste toner feed screwM 1[1]Toner ejection partBrush rollerDC Controller PCBM1 Main motor[1] Main motor drive signalF-2-59F-2-59Primary Charging Bias ControlThe machine is directly charged by the charging roller. DC bias and AC bias that stabilizedthe charge is applied to the primary charging roller.Photosensitive drum[2]Environment sensor[1]Primary charging rollerHVT PCBPrimary DC biascontrol circuitPrimary AC biascontrol circuitDC Controller PCB[1] Primary charging bias control signal[2] Environment sensor detection signalConstant voltage control of DC bias and AC biasThe DC bias and AC bias control circuits on the DC controller PCB control the DC bias andAC bias applied to the primary charging roller to keep their voltage at the fixed level.DC bias switch controlThe DC bias output varies according to the environment detected by the environment sensor(HU1).F-2-60F-2-60
