CHAPTER 4 IMAGE FORMATION SYSTEMCOPYRIGHT © 1999 CANON INC. CANON NP6512/6612/7120/7130/7130F REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)4-4C. Primary Charging Roller Bias Control1. OutlineFigure 4-103 shows the circuit used to control the voltage applied to the primary chargingroller, and has the following functions:• Turning on and off the DC bias.• Controls the DC bias to a constant voltage.• Switching the level of the DC bias.• Corrects the level of the DC bias automatically.The level of the DC bias applied to the primary charging roller is switched between image areaand non-image area.Reference:The level of the DC bias is as follows:Image area: -1376 V ± (correction value by APVC) ± (correction value * by density mode)Non-image area: -900 V ± (correction value by APVC); area between sheets-1000 V ± (correction value by APVC); cleaning area by transfer-600 V ± (correction value by APVC); trailing edge area*See p. 4-16.
