Canon 1000 Service Manual page 156

3. OPERATION AND TIMING
Each hopper for color toner is equipped with a toner sensor, which is a piezoelectric oscillator.
The front sensors (TS4, 5, 6) monitor the level of toner and, when the toner level falls below the sensor,
issues the message "ADD TONER" on the control panel when copying operation ends.
The rear sensors (error sensors TS1, 2, 3) look for sensor faults or damage to the stirring rod. If an error
sensor (TS1, 2, 3) detects the absence of toner while the toner level sensor (TS4, 5, 6) detects the presence
of toner, 'E020' will be indicated on the control panel when copying operation ends.
3-112
COPYRIGHT © 2001 CANON INC.
Rear
Error sensor
(TS1,2,3)
Figure 3-540
CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)
Front
Toner level sensor
(TS4,5,6)