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2. Development stage
Development places particles of toner onto
the areas of the drum that have been
cleared of
charge by the laser beam. This
makes a visible image.
the toner projection development method
with a single-component toner.
Step 3 Development
T,
i
DC bias
f
n5
Figure 2-23
Note:
The charges on the light areas on
the pholosensitive drum are shown
as positive in this figure. Actually
they are negative. hut they are
more positive than the developing
c y l i n d e r a n d
simplified by regarding them as
positive.
As shown in Figure Z-23. the developing
unit consists of a developing cylinder and
rubber blade. The developing cylinder
rotates around a fixed internal magnet.
The single-component loner consists of
magnetite and a resin binder, and is held
to the cylinder by magnetic attraction. The
toner is an insulator, and acquires a
negative charge by friction due to the
rotation of the cylinder.
The areas on the drum that were exposed
This printer uses
' i
Magnet
e x p l a n a t i o n i s
the laser beam have a higher potential
Lo
(are less negative1 than the negatively
charged toner particles on the developing
cylinder. When these areas approach the
cylinder, the potential difference projects
the toner particles onto them. This is
called toner projection, and the latent
image on the drum becomes visible.
Developing
cylinder
surface potential
t +"
s' 0~~~~
G
2
p _" /L-fkrR
Tlmet
-
Figure
An AC bias is applied to the developing
cylinder to help project the toner particles
to the drum surface and improve the
contrast of the printed image. The center
voltage of the AC bias (1600 Vp-p) varies
with the DC bias voltage.
The IMAGE DENSITY ADJUSTMENT
signal (sent from the DC controller to the
high-voltage power supply via the serial
line) changes the DC bias, and thus the
potential difference between the cylinder
and drum. This changes the density of the
print.
This printer has a stirring mechanism to
supply toner in the cartridge smoothly to
the cylinder.
Drum surface
p0tf?W3
(exposed area)
:-/
-. DC bias
z Drum surface
potenllal
(unexposed area)
2 - 2 4
2 - 1 9
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