Canon imageRUNNER ADVANCE C5255 Series Service Manual page 86

2
Technology > Image Formation System > Controls > Primary charging
■ Primary charging
● Overview
This machine uses the roller charging method for primary transfer.
To prevent image fault (white spot/missing image) caused by residual toner, the cleaning
brush roller is added to clean the primary charging roller.
Cleaning brush
2 Technology > Image Formation System > Controls > Primary charging
Drum
Photosensitive
cleaner
drum
Primary charging
roller roller
F-2-67
● Primary charging bias control
To charge the surface of photosensitive drum to be uniform negatively-charged potential
The primary charging bias (AC+DC negative), generated by HVT1/2 PCB, is applied to the
primary charging roller.
DC controller(UN1)
HVT1 /2(UN16/17)
AC + DC negative
Cleaning brush roller
● Discharge current control
To apply optimal primary charging bias according to the environmental change or use
condition of photosensitive drum
Execution timing
1) When the power is turned ON, at sleep recovery
2) At last rotation after printing 125 accumulated sheets, or at paper interval after printing 250
accumulated sheets (see Note1)
Note1: The number of accumulated sheets is counted by the counter common for color mode
and Bk mode.
Detection description
To detect the current monitoring value of the primary charging AC bias
2-48
Photosensitive
drum
Primary charging roller
F-2-68
2-48