Brother FAX-2820 Service Manual page 60

Transfer
(1) Transfer process
After the drum has been charged and exposed, and has received a developed image, the toner
formed is transferred onto the paper by applying a negative charge to the back of the paper.
The negative charge applied to the paper causes the positively charged toner to leave the
drum, and adhere to the paper. As a result, the image is visible on the paper.
(2) Cleaning process of transfer roller
If the toner is not transferred onto the paper perfectly it is possible that there may be residual
toner on the drum which will adhere to the transfer roller. The transfer roller voltage
changes to a positive voltage during non-printing rotation of the drum. Therefore the
transfer roller is cleaned by returning the positively charged toner adhering to the transfer
roller onto the exposure drum.
Fixing stage
The image transferred to the paper by static electricity is fixed by heat and pressure when passing
through the heat roller and the pressure roller in the fixing unit . The thermistor keeps the surface
temperature of the heat roller constant by detecting the surface temperature of the heat roller and
turning on or off the halogen heater lamp.
Heat roller
Pressure roller
3 - 1 5
Fixing unit
Halogen heater
Confidential