Laser Exposure (Step 3); Development (Step 4) - Canon GP200 Service Manual

2. COPYING PROCESS
E. Laser Exposure (step 3)
Laser light
Dark area Light area
Figure 2-107
In this step, a laser representing the dark
areas of the original is directed to the surface of
the drum to neutralize the existing charges. The
areas on the photosensitive drum which have
been exposed this way are called light areas and
will later attract toner in step 4 (development).
2–4
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F. Development (step 4)
In this step, the static image on the surface of
the drum is turned into a visible image by toner.
As shown in Figure 2-108, the developing
assembly consists of a developing cylinder (made
of a fixed magnet and a cylinder rotating around
it) and a magnetic blade.
The main ingredients of the toner are mag-
netite and resins. The toner has insulating prop-
erties and is charged to a negative potential by
friction against the cylinder.
The GP215/GP200 deposits toner over the
areas on the surface of the drum whose charges
have been neutralized by a laser beam (light
areas); for this reason, the polarity of the toner is
negative, which is the same as the polarity of pri-
mary charging.
Concentrated
magnetic field
Magnet
CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
Blade
Cylinder
Magnet
Developing
cylinder
Figure 2-108
Developer
Blade
Magnet
Figure 2-109