Canon 1000 Service Manual page 163

The Bk toner hopper is equipped with a toner sensor, which is a piezoelectric oscillator.
The level of toner inside the main hopper is monitored by a sensor (TS5), and the level of toner inside the
sub hopper is monitored by another sensor (TS4).
When the level of toner inside the sub hopper falls under the sensor, the message "ADD TONER" will be
indicated on the control panel after copying.
Toner level
sensor (upper)
(TS4)
Toner is supplied to the main hopper as follows:
When a specific period of time passes after toner supply operation, the signal from the sensor is read by
the DC controller; if the absence of toner is detected, the sub hopper starts to supply toner.
If the main hopper toner sensor (TS5) detects the absence of toner eight times in a row despite toner
supply operation, 'E020' will be indicated on the control panel after copying operation.
Bk toner supply clutch (upper; CL4)
Toner level sensor (lower; TS5)
Bk toner supply clutch (lower; CL5)
COPYRIGHT © 2001 CANON INC.
Toner level
sensor (lower)
(TS5)
Toner level detection (lower) signal (BKTEPL*)
Toner level detection (upper) signal (BKTEPU*)
Figure 3-550
Image formation
1.2 sec
Toner absent
Supply to developing
assembly
Figure 3-551
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
Sheet
Image formation
gap
0.7 sec
1.2 sec
Toner present
3. OPERATION AND TIMING
DC
controller
PCB
3-119