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1.
Formation
of Electrostatic
Latent
Image
Step 2 Primary corona
This block consists of the first three steps
of the image formation
process; at its end, the
areas of the drum corresponding
to dark areas
of
the
document
are
left
with
negative
charges,
and those representing
light areas are
rid of negative charges.
The pattern
of charges
so formed
is not
visible to the
human
eye and, therefore,
is
called an "electrostatic
latent image."
a
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,...
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r
: .,
'.
c
T
Time
ItI
Figure 2-4
Step 1 Pre-conditioning
exposure
Figure 2-5
In this step, or pre-conditioning
exposure,
the surface
of the drum is exposed
to light
from
the
pre-conditioning
exposure
lamp
through
a filter. All charges
remaining on the
surface
of the drum from the preceding
copy
cycle
are
eliminated
in preparation
for
ex-
posure
by the primary corona.
Such charges,
if left as they are, could result in copies with
uneven density.
Figure 2-6
In this step, the drum is charged
by the
_,-~
primary
corona.
Further, the drum is charged
uniformly
by the grid. As a result, its surface
will come to have a uniform layer of negative
\i
charges and maintain primary potential.
step 3
Scanning exposure
Optical
image
I
._.,.,._.,._.,.,._._.,.,.,.,.,.,.,
,.; _.,.
.,.;_
Figure 2-7
In this step, the optical image of the docu-
ment is projected
on the surface
of the drum
to neutralize the charges over areas meant to
be light.
._.
_.
I -.
2-2
COPVAI6HT
01988
CANON INC.
CANON WP-IOIO
NIV.0
DEC. 1988 PAINTED
IN JAPAN IIMPAIME
AU JAPONI
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