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Primary transfer bias generation
The primary transfer biases (TR11, TR12, TR13, TR14) are output to transfer the toner on
the photosensitive drum to the ITB. They are the DC positive biases, one for each color (C,
Y, M, K), generated in the primary transfer high-voltage generation circuit in the high-voltage
power supply circuit. The high-voltage power supply circuit applies them to the primary
transfer charging rollers in each cartridge at the specified time.
The values of these biases vary according to the commands from the DC controller.
Secondary transfer bias generation
The secondary transfer bias TR2 is output to transfer the toner on the ITB to paper.
There are two kinds of biases, one DC positive, and the other DC negative. They are
generated in the secondary transfer high-voltage generation circuit in the high-voltage power
supply. The high-voltage power supply circuit applies them to the secondary transfer
charging roller according to the following print sequences.
● Print bias (DC positive): The bias to transfer the toner on the ITB to paper during the
printing process.
● Between-sheets bias (DC positive): The bias to prevent the residual toner on the ITB
from adhering to the secondary transfer roller during continuous printing.
● Cleaning bias (DC positive/negative): The bias to put the toner adhered to the secondary
transfer roller back to the ITB.
The values of these biases vary according to the commands from the DC controller.
The DC controller adjusts the voltage of the transfer bias constant according to the
TRANSFER CURRENT FEED BACK signal (TR2S) sent from the secondary transfer high-
voltage generation circuit. The DC controller also controls the rated current.
Fuser bias generation
The fuser bias (FSR) is output to prevent the toner on the paper from adhering to the fuser
sleeve before fuser process.
It is the DC positive bias generated in the fuser high-voltage generation circuit in the high-
voltage power supply circuit. The high-voltage power supply circuit applies this bias to the
pressure roller of the fuser unit at the specified time.
134 Chapter 5 Theory of operation ENWW