In A+ Printers Part 1 about 1:13:15 there is a graphic of the transferring stage of printing. I think I have this confused.
In step 4 the areas on the EP Drum that are -100VDC are where the toner will adhere and the excess toner falls away if it has the like charge of -600VDC. So in the transferring phase why is the paper charged to +600VDC instead of +100VDC. I keep thinking that you only want to attract the toner on the EP drum (+100VDC) to the paper.
Step 5:: Printer Transferring Phase
What must occur during the transfer phase is for the paper to attract the toner. If the toner on the EP drum is ~ -100VDC and the paper is ~ +100VDC the charge is essentially cancelled. The transfer corona produces a +600VDC charge to give us a voltage differential to attract the toner from the drum.
Cool Thanks Ronnie