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2.
COPYING PROCESS 0
The outer surface of the photosensitive
drum is a layer of organic
photoconductor
(OPC). The base is an aluminum
(conduc-
tive) cylinder.
Photoconductive
layer
Base
Figure 2-3
B. Electrostatic
Latent Image
~
Formation Block
i
i/.-- \
This stage consists
of three steps. At
the end of the stage, the drum has a pattern
of negative
electrical charges on its surface
corresponding
to the dark
parts
of the
document
image.
The light
areas
of the
document
image
are represented
on the
drum by the absence of charges.
The pattern of negative charges cannot
be seen by the eye, hence it is called an
electrostatic
latent image.
Of-
Time (1) -
Dark area
Figure 2-4
C. Step 1 Pre-Exposure
Figure 2-5
Before
the primary
corona
step, light
from the pre-exposure
lamp is shone onto
the surface of the drum (pre-exposure).
This
process
eliminates
residual
charges
and'
helps to make the density of the copy even.
D. Step 2 Primary Corona
Primary corona assembly
Figure 2-6
The primary corona (negative)
applies
a uniform layer of negative charges over the
drum surface.
The drum surface
potential
is deter-
mined
bv the arid ootential.
The grid is
connected
to ground
through
which holds the drum potential
the varistor break-down
voltage.
a varistor,,
constant
at
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