CHAPTER 4 IMAGE FORMATION SYSTEMCOPYRIGHT © 1999 CANON INC. CANON NP6320 REV.0 DEC. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)4-14VI. DEVELOPING ASSEMBLY/DRUM CLAENERA. OutlinesThe paddle inside the drum cleaning unit and also the developing cylinder are rotated by themain motor.The amount of toner in the developing assembly is sensed by the black toner level sensor(TS1).When the amount of toner falls below the required quantity, the Add Toner indicator on thecontrol panel will flash.The toner collected by the cleaning blade is stored in the drum cleaning unit.The developing assembly is pressed against the drum by the cams that press against the devel-oping assembly rail. (The cams are operated by the developing assembly release lever.)B. Remaining Toner SensorThe black developing assembly has a piezoelectric type sensor (TS1) which senses if the tonerremaining in the hopper of the developing assembly is above or below the required level.When the amount of toner in the hopper is sufficient, the sensor output is ‘1’. When it is belowthe specified level, the output is ‘0’.The DC controller makes checks for 30 seconds during copying, if the TONER EMPTY signal(BTEP) is being outputted. If the signal is outputted continuously for 30 seconds, it is regarded asTONER OUT and the DC controller makes the Add Toner indicator flash.Figure 4-601C. Torque LimiterThere is a torque limiter in the drive train between the main motor and the drum to stop thedrum in response to a jam in the drum cleaner.PhotosensitivedrumDeveloping cylinderPaddleDC controller PCBDeveloping assemblypositioning camBlack developingassemblyBlack toner levelsensor (TS1)Main motorDrum cleaning unit TorquelimiterCleaningblade Pressed ReleasedDeveloping assembly rail unitStirrerTONER EMPTYsingnal(TEP)M1
