COPYRIGHT © 1999 CANON INC. CANON 660/2100 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)1. Primary Transfer Bias Generation CircuitThis circuit is controlled by three signals (Figure 4-602) generated by the DC con-troller PCB, and generates the primary transfer DC (positive) bias and primary transferDC (negative) bias for application to the intermediate transfer drum.The primary transfer DC (positive) bias drive signal turns on and off the DC (positive)bias applied to the intermediate transfer drum. The primary transfer DC (negative) biasdrive signal, on the other hand, is used to turn on and off the DC (negative) bias appliedto the intermediate transfer drum.The primary transfer bias level control is used to switch the levels of the primary trans-fer DC (positive) bias. (See Note.)Figure 4-602Note:The level of the primary transfer DC (positive) bias differs between mono-color print-ing and full-color printing.In the case of full-color printing, four color toners are deposited on the intermediatetransfer drum for primary transfer; as such, the toner with negative charges increasesfor the second and subsequent colors, requiring increased transfer strength. To thisend, the copier increases the primary transfer bias DC component when it deals withthe second and subsequent colors.CHAPTER 4 IMAGE FORMATION SYSTEM4-25DC controllerPCBPrimarytransfer biasgenerationcircuitPrimary transfer DC (positive)bias drive signalPrimary transfer DC (negative)bias drive signalPrimary transfer bias level controlsignalIntermediatetransfer drumDC (positive)orDC (negative)Download free service manual at http://printer1.blogspot.com
