Canon IR2200, IR3300 Temperature Correction of the DC Bias, Humidity Correction of the AC Bias

CHAPTER 4 IMAGE FORMATION SYSTEM

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.

Primary DCbias	-800V
	-750V
	(reference
	value)
	23˚C	40˚C

LowHigh

Machine inside temperature

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.

Counter reading: 0 to 10,000 sheets Counter reading: 10,001 or higher

	2300µA
bias	2150µA
AC
Primary	2000µA
	Low	35%	High	Low	35%	High
		Humidity			Humidity
			F04-205-01

4-6 P COPYRIGHT © 2001 CANON INC. CANON iR2200/iR2800/iR3300 REV.0 MAR. 2001