Canon NP2120 Service Manual page 76

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;
toner.
The toner collected by the cleaning blade is
stored inside the drum cleaning unit.
Thedevelopingassemblyisbrought
with the photosensitive drum together with the
developing assembly rail by the developing assem-
bly release lever.
D r u m c l e a n i n g unit
3 - 3 6
2. Monitoring the Toner Level
A piezoelectric oscillator toner sensor (Q9) is
provided inside the black developing assembly to
monitor the level of toner.
as a specific level of toner is inside the assembly;
whenthetonerdecreases belowthelevel,theoutput
goes '0'.
The DC controller reads the output signa1 for 5
'O'continuously, it recognizes 'no toner 1'. When 'no
toner 2' is recognized, the DC controller flashes the
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.
intocontact
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.
Figure 3-35
C A N O N NPZl20/2MO RN.0 M A Y 1990 PRINTEO I N J A P A H IIMPRIME AU JAPONI
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