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OPERATIONS AND TIMING
COPYRIGHT
©
1998 CANON INC. CANON NP6621 REV.0 FEB. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
q If the toner is more than a specific level,
Since toner exists around the toner level sensor,
the AC bias generated by the sensor is greater
than the reference signal.
In this condition, the output of the comparator
circuit goes ‘1’ and the toner absent signal
(TEP*) goes ‘0’.
w If toner is less than a specific level,
Since toner around the toner level sensor
decreases, the AC bias generated by the sensor
decreases.
On the other and, the output voltage remains
high since the reference signal remains
unchanged.
The difference in potential causes the output of
the comparator circuit to go ‘0’ and the toner
absent signal (TEP*) to go ‘1’.
The microprocessor (Q301) on the DC controller
circuit checks the level of toner only during
copying operation (AC bias ON); if it continuously
detects the toner empty signal 0 for 3 min or
more, it flashes the REPLACE CARTRIDGE
message on the control panel after finishing the
ongoing copying run.
e Torque Limiter
If an excess load is imposed on the
photosensitive drum as when the waste toner
becomes full while the photosensitive drum is
rotating, the torque limiter turns on to stop the
rotation of the photosensitive drum by cutting
the drive from the main motor.
STBY
Copy Start key
ON
Main motor (M1)
Toner level detection
Toner absent signal (TEP*)
AC bias
Power switch
ON
REPLACE CARTRIDGE
message flashed
A43, AE, 3 copies, continuous.
REPLACE CARTRIDGE
message (flashed)
1st (3 sec)
2nd (1 sec)
3rd (0.5 sec)
Copy STBY Copy STBY Copy
Figure 3-314