CHAPTER 4 IMAGE FORMATION SYSTEMCOPYRIGHT © 1999 CANON INC. CANON NP6317 REV.0 APR. 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 a cam that presses against the devel-oping assembly rail. (The cam is 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 developimg assembly is sufficient, the sensor output is '1'.When it is below the specified level, the output is '0'.The DC controller PCB checks for 40 sec during copying if the TONER EMPTY signal (TEP)is being outputted. If the signal is outputted continuously for 40 sec, it is regarded as "TONEROUT" and the DC controller PCB makes the ADD TONER indicator flash.Figure 4-601Main motorPaddle Developing cylinderTONER EMPTY signal(TEP)Drum cleaning unit Torquelimiter Black developingassemblyBlack toner levelsensor(TS1)Developing assemblypositioning camDeveloping assemblyrail unitStirrerPhotosensitivedrumReleasedPressedCleaning bladeM1DC controller
