C. Controlling the Developing Bias/Roller Electrode1. OutlineDuring copying, both AC bias and DC bias are applied to the developing cylinder. TheDC bias is a voltage which is the sum of 100 V and V L2 measured by the potential sensorbefore copying is started.When the machine is not making copies, the degree of the DC bias is varied to suitthe surface potential of the drum to prevent adhesion of excess toner on the photosen-sitive drum.Figure 4-2042. Control TimingTable 4-201 PhotosensitivedrumDeveloping cylinderVDBDark areaLight areaBiasVDB = VL2 + 100 [V]TonerCHAPTER 4 IMAGE FORMATION SYSTEM4-32 COPYRIGHT © 1997 CANON INC. CANON NP6560/NP6360/NP6260 REV. 0 NOV. 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)BiasDCcomponentAC component 1500 Vp-p,2700 HzVoltage+600V+600VV L2 +100 [V]PeriodCNTR1, 2INTR, AER, LSTRduring copyingSCFW, SCRVduring copyingDescriptionTo prevent adhesion of excess toner on thedrum. (The surface potential varies con-stantly, and is measured by the potentialsensor at all times.)To prevent adhesion of excess toner on thedrum.To prevent fogging of the background.To execute toner projection.
