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The outer surface of the photosensitive
drum is a layer of organic photoconductor
(OPC). The base is an aluminum (conductive)
cylinder.
Photoconductive
layer
Base
Figure 2-3
2. Electrostatic
Latent
Image
Formation
Block
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 an absence of charges.
The pattern of negative charges cannot
be seen
by eye,
hence
it is called
an
electrostatic
latent image.
T
Time
(t)
-
Figure 2-4
3. Step 1 Preconditioning
Exposure
Figure 2-5
Before the primary
corona step, light
from the preconditioning
exposure lamps is
shone onto the surface of the drum (precon-
ditioning
exposure).
This
process
elimi-
nates residual charges and helps to make
the density of the copy even.
2-2
COPYAIGHT
0
1988 CANON INC
4. Step 2 Primary Corona
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 by the grid potential.
The grid is
_
connected
to ground through
a varistor,
which holds the drum potential constant at
Jo
the varistor break-down voltage.
5. Step 3 Scanning Exposure
Light
image
Figure 2-7
Light from the original is projected onto
the drum surface.
Charges in these light
areas on the drum are neutralized by drum
photoresistive
effects.
CANON HP-1015/1215S
AN.0
OCT. 1988 PAINTELI
IN JAHN
[IMPRIME
AU JAPONI
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