Brother MFC-9420CN Service Manual page 45

3 Developing
Developing process means that an electrostatic latent image on OPC belt is made visible with
toner.
(1) Structure of toner cartridge PU (Refer to Fig.3-9 & 3-15.)
1) Toner cartridge PU is located as shown in Fig.3-9.
2) Four toner cartridges are made available from the top to bottom in the order of
specified color as black, yellow, magenta and cyan.
3) Each color toner is loaded in the corresponding toner cartridge PU.
(2) Process of developing (Refer to Fig.3-9, 3-15, 3-16, and 3-17.)
1) Toner adheres to the Dev.roller of toner cartridge PU.
Developing is processed by this Dev.roller contacting the OPC belt surface.
2) Dev.roller has been biased to the potential -DBV(V). Fig.3-16 describes the
relationship established between the potential of toner, the potential -V
non-exposed area of OPC belt and the potential -VR(V) at the exposed area of OPC
belt.
3) Developing is processed by the toner adhering to the OPC belt due to the attraction
between the potential of toner and the potential -VR(V) at the exposed area of OPC
belt. (Toner image is formed (visible) on the OPC belt.)
4) On the other hand, no development takes place at the non-exposed area because the
potential of toner and that of OPC belt is identical pole and therefore repels each
other.
Fig. 3-15
3 - 1 3
(V) at the
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