Technical information

m OPERATIONSANDTIMING
G. Developing Assembly and
Drum Cleaning Unit
1. Outline
The blade and developing cylinder inside the
drum cleaning unit are rotated by the drive from the
main motor.
The level of toner inside the black developing
assembly is monitored by the toner sensor (Q9):
and, whenthefevelfalls belowaspecifiedvalue, the
ADD TONER indicatoron the control panel starts to
flash.
The CT unit cannot be replenished with tener;
replace the CT unit as a whole when it runs out of
toner.
The toner collected by the cleaning blade is
stored inside the drum cleaning unit.
Thedevelopingassemblyisbrought intocontact
with the photosensitive drum together with the
developing assembly rail by the developing assem-
bly release lever.
2. Monitoring the Toner Level
A piezoelectric oscillator toner sensor (Q9) is
provided inside the black developing assembly to
monitor the level of toner.
Theoutputofthetonersensorremains’i’as long
as a specific level of toner is inside the assembly;
whenthetonerdecreases belowthelevel,theoutput
goes ‘0’.
The DC controller reads the output signa1 for 5
sec aftercopy operation is over; if the signa1 remains
‘O’continuously, it recognizes ‘no toner 1’. When ‘no
toner 2’ is recognized, the DC controller flashes the
ADDTONERindicatorandprohibitscopyoperation.
The CT unit is not equipped with a toner level
detection mechanism, or the cleaning unit is not
equipped with a waste toner level detection mecha-
nism.
3. Torque Limiter
If a large load is imposed on the photosensitive
drum while the drum is rotating forsome reason, the
torque limiter cuts off the drive from the main motor
to stop the rotation of the drum.
Drum cleaning unit
G DL”, as*embly rail
Figure 3-35
3-36
COPYAIGHT Q 1992 CANON INC.
CANON NPZl20/2MO RN.0 MAY 1990 PRINTEO IN JAPAH IIMPRIME AU JAPONI