Canon NP6012 Service Manual page 40

lm COPYING PROCESS
E. Image Exposure (step 3)
Optical image
Lt
Light area
LL
Dark area
Figure 2-107
In this step, the optical image of the orig-
inal is projected to the photosensitive drum
to neutralize the charges in the light area.
2-4 COPYRIGHT © 1995 CANON INC.
F. Development (step 4)
_, Blade
> al Developing
Magnet J cylinder
Figure 2-108
As shown in Figure 2-108, the develop-
ing assembly consists of a rubber blade and
a developing cylinder constructed of a fixed
magnet and a cylinder that rotates around it.
The copier's toner is a one-component toner
made mostly of magnetite and resins. The
toner has insulating characteristics and
becomes positively charged by the friction
between the rotating cylinder and the blade.
The toner is moved between the rotating
developing cylinder and a blade, where it is
charged to a positive potential and deposited
on the developing cylinder in a thin, uniform
layer.
The developing cylinder receives both
AC bias and DC bias (negative component)
at the same time; the resulting bias is called
developing bias. For this reason, the nega-
tive component of the developing bias is
greater than the positive component.
Positive component
Negative component
DC bias
Figure 2-109
CANON NP6012/NP6O12E/NP6212 REV.1 SEPT. 1995 PRINTED IN JAPAN (IMPRIME AU JAPON)