Latent Image Formation Block - Canon GP200 Service Manual

2. COPYING PROCESS
The GP215/GP200's image formation process
consists of the following steps as discussed in
sequence:
Step 1 Pre-exposure
Step 2 Primary charging (AC + negative DC)
Step 3 Laser exposure (AC + negative DC bias)
Step 5 Transfer (positive DC)
Step 6 Separation (negative DC)
Step 7 Fixing
Step 8 Drum cleaning
The photosensitive drum has a layer construc-
tion: the outside is a photoconducting layer of
OPC and the inside, conductive aluminum sub-
strate.
Figure 2-103
2–2
COPYRIGHT © 1996 CANON INC.
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Surface
Photoconductive
potential (V)
Substrate
CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
B. Latent Image Formation
Block
The latent image formation block consists of
three steps, at the end of which negative charges
are left behind in the areas on the drum corre-
sponding to the white areas of the original and
negative charges are removed from the areas on
the drum corresponding to the black areas of the
original.
Such images on the drum created by negative
charges are not visible to the human eye and are
therefore called static images.
Time (t)
Light areas
(dark areas of originals)
-500
Dark areas
(areas not exposured by the laser)
-1000
Laser exposure (step 3)
Figure 2-104