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2001 CANON INC. 2000 2000 2000 2000 CANON iR2200/iR2800/iR3300 REV.0 MAR. 2001
CHAPTER 4 IMAGE FORMATION SYSTEM
4-6 P
2.4 Temperature Correction of the DC Bias
When the temperature inside the machine increases, the resistance of the photosensitive
drum will decrease, thereby lowering the charging characteristics. To ensure a stable poten-
tial level, the drum sensor (U701) mounted to the rear side plate is used to check the tem-
perature inside the machine; when the temperature increases, the absolute value of the DC
bias level is increased.
F04-204-01
2.5 Humidity Correction of the AC Bias
The current level of the AC bias needs to be kept on the higher side to prevent uneven
charging because of a lower changing efficiency occurring in a low-humidity environment.
The AC bias, therefore, is varied as shown in F04-205-01 to suit the readings of the environ-
ment sensor (humidity). When the resistance of the drum surface decreases because of ad-
vancing wear, the current level is decreased to facilitate the flow of current.
F04-205-01
Primary DC bias
-750V
-800V
Machine inside temperature
High
Low
(reference
value)
23˚C 40˚C
Primary AC bias
2150µA
2000µA
2300µA
Humidity
High
Low
Counter reading: 0 to 10,000 sheets Counter reading: 10,001 or higher
35%
Humidity
High
Low
35%