Controls; Drum Unit - Canon imageRUNNER 1750 Series Service Manual

2
Technical Explanation > Image Formation System > Controls > Drum Unit

Controls

■ Drum Unit

The Drum Unit mainly consists of the Photosensitive Drum, Primary Charging Roller, Brush
Roller, Cleaning Blade and Waste Toner Feed Screw, and is driven by the Main Motor (M2).
The Cleaning Blade is in contact with the surface of the Photosensitive Drum to remove
residual toner on the surface of the Photosensitive Drum that was not transferred to the
paper. Residual toner collected by the Cleaning Blade is sent from the Toner Ejection Mouth
to Waste Toner Box by the Waste Toner Feed Screw. The Brush Roller is also in contact with
the Primary Charging Roller, and the Brush Roller cleans the Primary Charging Roller.
Cleaning Blade
Brush Roller
Primary
Charging Roller
Toner Ejection Part
M2 Main Motor
[1] Main Motor drive signal
● Drum Unit Detection
Charging AC bias is applied at Power-on, recovery from sleep state, or opening/closing the
door to detect the Drum Unit by the return value.
2 Technical Explanation > Image Formation System > Controls > Drum Unit
Waste Toner Feed Screw
M 2
Photosensitive Drum
[1]
DC Controller PCB
F-2-68
● Primary Charging Bias Control
This machine performs direct charging by the Charging Roller. AC bias is applied to the
Primary Charging Roller to make steady DC bias and charging.
Primary charging roller
HVT PCB
Environment sensor
[2] [1]
Primary AC bias
control circuit
DC Controller PCB
[1] Primary charging bias control signal
[2] Environment sensor detection signal
● DC/AC bias constant voltage control
The DC bias control circuit and AC bias control circuit in the DC Controller PCB control DC
bias and AC bias, which are applied to the Primary Charging Roller, to make constant voltage.
● DC bias switch control
DC bias changes output value of DC bias according to the environment detected by the
Environment Sensor (THU1).
2-44
Photosensitive drum
Primary DC bias
control circuit
F-2-69
2-44