Sharp MX-M550U Service Manual page 341

2. Operational descriptions
A. Outline
In this section, laser beams are radiated to the OPC drum surface
which was negatively charged, making electrostatic latent images.
B. Description
The OPC drum surface is negatively charged by the main charger.
The laser beam images are radiated to the OPC drum surface by
the laser unit to form latent electrostatic images.
1) The OPC drum surface is negatively charged by the main
charger.
High voltage unit
CTL
CGL
Aluminum
layer
The main charger grid is provided with the screen grid. The
OPC drum is charged at a voltage virtually same as the volt-
age applied to the screen grid.
2) LED lights are radiated to the OPC drum surface by the laser
unit to form latent electrostatic images.
LED lights
OPC drum
When laser lights are radiated to the OPC drum CGL, negative
and positive charges are generated.
Positive charges generated in CGL are attracted to the nega-
tive charges on the OPC drum surface. On the other hand,
negative charges are attracted to the positive charges in the
OPC drum aluminum layer.
Therefore, positive charges and negative charges are bal-
anced out on the OPC drum and in the aluminum layer, reduc-
ing positive and negative charges to decrease the OPC drum
surface voltage.
Electric charges remain at a position where LED lights are not
radiated.
As a result, latent electrostatic images are formed on the OPC
drum surface.
Main corona unit
Screen grid
OPC drum
OPC drum
CTL
CGL
layer
Aluminum
MX-M700N PHOTOCONDUCTOR SECTION J – 3
3) After transfer operation, remaining toner is removed by the
cleaning blade.
Drum
Toner removed from the OPC drum surface is transported to
the waste toner section in the toner cartridge by the waste
toner transport screw.
4) The whole surface of the OPC drum is discharged.
Lamp
CLT
CGL
layer
Auminum
By radiating the discharge lamp light to the discharge lens,
light is radiated through the lens to the OPC drum surface.
When the discharge lamp light is radiated to the OPC drum
CGL, positive and negative charges are generated.
Positive charges generated in CGL are attracted to the nega-
tive charges on the OPC drum surface. On the other hand,
negative charges are attracted to the positive charges in the
aluminum layer of the OPC drum.
Therefore, positive and negative charges are balanced out on
the OPC drum surface and in the aluminum layer, reducing
positive and negative charged to decrease the surface voltage
of the OPC drum.
Drum
C. Main charger
The OPC drum surface is negatively charged in this section.
CLT
CGL
layer
Auminum