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CHAPTER 2
1. Electrostatic latent image formation
stage
This stage has two steps, which together
produce a pattern oi elerlrical charges on
the photosensitive drum.
At the end of the stage. negative charges
remain in the unexposed "dark" areas.
Charges are absent from the "light" areas,
where the laser beam struck (exposed) the
drum surface.
Since this image of negative charges on
the drum is invisible to the eye, it is called
an "electrostatic latent image".
Figure 2-20
S
t
e
p 1
Figure
As preparation for latent image formation,
a uniform negative potential is applied to
the photosensitive drum surface. The
printer uses the charging method that
directly charges the drum for the primary
charge.
2-18
Primary charge
2-21
The primary charging roller consists of
conductive rubber. In addition to DC bias,
AC bias is applied to the primary charging
roller to keep the potential on the drum
surface uniform. This DC bias is changed
with the developing DC bias.
This charging melhod has advantages
such as lower applied voltage. less ozone
generation, etc., compared with the corona
charge system.
Step 2 Scanning exposure
Figure 2-22
When the laser beam scans the drum
surface. it causes the charge to be
neutralized in the areas struck by the
beam. Areas on the drum with no charge
form the electrostatic latent image.
Laser beam
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