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Step 3 (Development): Toner is attached to the latent electrostatic
images formed on the OPC drum.
Toner enters between the developing roller and the doctor, and a thin
layer of toner (a certain fixed amount) is formed on the developing
roller by a pressure applied to the doctor.
Toner is negatively charged by friction when passing between the
developing roller and the doctor.
When the OPC drum surface area where there is no charges be-
cause of exposure of laser beams is brought into contact with the
developing roller, toner is moved from the developing roller to the
OPC drum surface. The principle of the process is as follows:
A bias voltage of –310V is applied to the developing roller. Toner
which is charged by potential difference between the bias voltage and
the OPC drum surface potential is attracted to the OPC drum surface
(positively charged).
At that time, the potential of the OPC drum surface where there is no
charge by exposure of laser beams is higher than the developing
roller potential. On the other hand, there are negative charges in the
OPC drum surface area which is not exposed to laser beams. When
that area is brought into contact with the developing roller, if toner is
attached to the OPC drum,. toner is moved to the developing roller
which is in a high potential than the OPC drum.
As a result, unnecessary toner and paper dust on the OPC drum are
collected in the developing unit.
In this operation, toner is moved from the OPC drum to the develop-
ing roller.
In cleaning operation mode, DC +200V is applied to the developing
roller and cleaning capacity is further increased.
Step 4 (Transfer): Visible images of toner on the OPC drum are
transferred to the paper.
A high voltage of AC60V (P-P) is applied to DC+350V and applied to
the transfer roller, generating electric discharge between the roller
and the OPC drum, generating positive and negative charges.
CGL
CTL
100V
DC
+200V
DC
-310V
Developing roller
Doctor
:Toner (Negative charge)
Toner supply roller
OPC drum
Exposure area
(Exposed by
laser beams.)
Non-exposure area
(Not exposed by
laser beams.)
Aluminum layer
(Drum base)
Earth sheet
DC+3500V
DC –850V
AC600V(P-P)
CGL
CTL
OPC drum
Aluminum surface
(Drum base)
Paper
Transfer roller
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