Controlling The Toner Level Detection - Canon NP6218 Service Manual

B. Controlling the Toner Level Detection
The level of toner inside the cartridge is monitored by the antenna sensor circuit.
The toner level sensor is found inside the cartridge, and an AC bias is applied to the
developing cylinder.
The developing cylinder and the toner level sensor are connected by means of static
electricity; the volumes of charges between the two vary according to the amount of
toner inside the cartridge; as a result, an AC bias that represents the level of the toner
is checked by the toner level sensor, and the data is sent to the antenna sensor circuit.
The antenna sensor circuit receives a reference signal from the composite power
supply circuit; the reference signal is an AC bias with a specific AC bias that has gone
through attenuation.
In the antenna circuit, the signal coming from the toner level sensor and the
reference signal are compared to find out the level of toner.
Blade mount
Toner
Blade
Developing cylinder
COPYRIGHT © 1997 CANON INC.
Toner level
Developing assembly
sensor
frame
Figure 4-202
CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 4 IMAGE FORMATION SYSTEM
Antenna sensor circuit
Comparator circuit
DC controller
PCB
TEP*
4-23