Canon iR2018 Series, Руководство по обслуживанию

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Chapter 6
6-7
6.6.2 Developing Bias Control
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A DC bias and an AC bias are applied to the developing cylinder.
The ASIC on the DC controller PCB outputs the developing AC bias drive signal (/DVACFOT), developing AC bias ON/OFF signal (/DVACON), developing DC
bias drive signal (/DVDCFOT), and developing DC bias output level signal (/DVDCPWM) to apply the voltage generated by superimposing the developing AC
bias over the developing DC bias to the developing cylinder.
To prevent fogging of the drum, a DC bias higher than usual applied except during image formation and when the developing AC bias is applied for warm-up
rotation.
The developing DC bias is detected by the developing DC bias detection circuit, and is fed back to the DC generation circuit via the comparison circuit, thus con-
trolling the DC bias voltage. The developing DC bias voltage changes with the primary DC bias voltage according to the image density information sent from the
image processor PCB.
The remaining toner level is detected during warm-up rotation and when the developing AC bias is applied for printing. The remaining toner level detection signal
(TNRCHKT) sampled from the antenna (for remaining toner level check) in the developing assembly is compared with the reference signal (TNRCHKD) received
from the developing bias detection circuit.
F-6-10
6.7 Toner Container
6.7.1 Outline
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The structure of the toner bottle is shown below.
The toner bottle is charged with 1-component, insulating, magnetic toner. The stirring rod in the toner bottle is rotated by the mina motor to supply toner into the
developing assembly through the toner supply port.
F-6-11
[1] Stirring rod
[2] Toner bottle lever
[3] Toner supply port
JP7/JP8
JP1/JP2
TNRCHKT
TNRCHKD
/DVACFOT
/DVDCPWM
/DVDCFOT
To developing
cylinder
From remaining
toner level sensor
Developing bias circuit
ASIC
CPU
Developing DC bias
voltage detection circuit
Developing AC bias
current detection circuit
Remaining toner level
detection circuit
DC generation circuit
AC generation circuit
Comparison
circuit
/DVACON
Superimposition
High-voltage power supply PCB
DC controller
PCB
[1]
[3]
[2]