Brother MFC-9420CN Service Manual page 51

7 Second Transfer (Paper)
Second transfer process means that the toner image on the transfer belt is transferred onto the
transported paper.
(1) Structure of belt cleaning
1) Transfer roller for the second transfer is located as shown in Fig.3-9.
2) Transfer roller is normally separated from the transfer belt.
3) Transfer roller is positively biased by the power supply THV.
4) Transfer roller contacts to the transfer belt in the second transfer process.
5) Transported paper passes between the transfer roller and transfer belt.
(2) Process of belt cleaning (Refer to Fig.3-22.)
1) Paper is transported as synchronizing with the transfer belt.
2) Transfer roller operates as synchronizing with the transported paper, and contacts
with the transfer belt through the transported paper.
3) Transported paper passes between the transfer roller and transfer belt. In this instance,
the positive high voltage (THV) is injected to the transfer roller.
4) Negatively charged toner is moved to the positively charged paper.
5) Transported paper with the toner transferred is transported to the paper discharging
process.
Transfer Roller
+THV
Transfer Belt
Transfer Unit
Registration Roller
Paper
Fig. 3-22
3 - 1 9
THV: Power Supply for Transfer
Roller Bias.
Confidential