Transfer block The image is built up on the transfer drum in layers of toner. The toner is then transferred to the paper. The transfer block includes the transfer of the toner from the imaging drum to the transfer drum, then from the transfer drum to the paper. 5. Primary transfer A positive DC bias is applied to the transfer drum during printing to transfer the toner that is on the imaging drum to the transfer drum. This process occurs in sequence for the four colors (yellow, magenta, cyan, black). For full-color printing, as the transfer steps proceed for the four colors, the amount of toner with negative charge increases on the transfer drum.
As a result, the DC bias must increase to transfer the toner on top of the toner that is already on the transfer drum. Figure 29. Primary transfer 146 Chapter 5 - Theory of operation EN