Temperature Correction Of The Dc Bias; Humidity Correction Of The Ac Bias - Canon iR2200 Service Manual

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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.

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

Machine inside temperature

Counter reading: 10,001 or higher

2000 2000 2000 2000

CANON iR2200/iR2800/iR3300 REV.0 MAR. 2001

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Ir2800 Ir3300