Brother HL-1470N, Service Manual

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CHAPTER 3 THEORY OF OPERATION
3-30
2.6.4 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 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 photo-conductive drum.
2.6.5 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.
Fig. 3-38
First eject roller
Thermistor
Pressure roller
Heat roller