Canon NP6218, FY8-13EX-000 service manual 4-24, q When the Level of Toner Is Adequate

CHAPTER 4 IMAGE FORMATION SYSTEM

qWhen the Level of Toner Is Adequate

The presence of toner around the toner level sensor causes the AC bias generated

by the sensor to be larger than the reference signal.

The condition causes the output from the comparator circuit to go ‘1’ and the toner out signal (TEP*) to go ‘0’.

wWhen the Level of toner Is Inadequate

The toner around the toner level sensor decreases in amount, causing the AC bias generated by the sensor to lower.

Since the reference signal, on the other hand, remains unchanged, the output voltage remains high.

The difference in the potential causes the output of the comparator circuit to go ‘0’, causing the toner out signal (TEP*) to go ‘1’.

The condition causes the microprocessor (Q301) in the DC controller cirucit to make checks only during copying operating (AC bias ON); if it detects the toner out signal=0, each lasting 0.25 sec or more, for a total time equivalent of three copies, the Cartridge indicator is flashed on the display of the control panel.

eTorque Limiter

If an excessive load is imposed on the photosensitive drum because of excessive

amounts of waste toner or some other reason while the drum is rotating, the torque limiter cuts off the drive from the main motor to stop the rotating of the drum.

Power switch	Copy Start key					Cartridge indicator
ON	ON					flashing timing
STBY		Copy	STBY	Copy	STBY	Copy

Main motor (M1)
Toner level detection timing
	1st (3 sec)	2nd (1 sec)	3rd (0.5 sec)
Toner out signal (TEP*)
AC bias

Cartridge indicator (tlashing)

A4, AE3 copies, continuous mode

Figure 4-203

4-24 COPYRIGHT © 1997 CANON INC. CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)