Transfer (Step 5) - Canon GP200 Service Manual

A concentrated magnetic field occurs from the
magnet to the edge of the blade, attracting toner.
Once inside the field, the toner becomes virtu-
ally immobile because of the strong bond with the
blade so that, when deposited, it forms an even,
thin layer on the cylinder.
An AC bias and a DC bias (negative compo-
nent) are applied to the developing cylinder and
the blade at the same time (developing bias); the
negative component of the developing bias is
stronger than the positive component.
DC bias
Figure 2-110
During copying, toner is attracted to the light
areas of the photosensitive drum by the work of
the negative component of the developing bias,
thereby turning the latent image into a visible
image. The excess toner is removed from the
photosensitive drum by the positive component of
the developing bias and the drum surface poten-
tial.
COPYRIGHT © 1996 CANON INC.
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Positive component
Negative component
CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
G. Transfer (step 5)
Transfer
roller
Figure 2-111
Positive charges are applied to the back of the
copy paper by the transfer roller to transfer the
toner image from the drum surface to copy paper.
The GP215/GP200 uses a roller transfer
method, which requires less transfer voltage than
a corona transfer method and generates virtually
no ozone.
To prevent transfer faults or soiling of the back
of copy paper, the transfer guide is given a nega-
tive bias.
Reference:
If the transfer guide was grounded, the
charges for use on the back of copy paper
would escape, leading to transfer faults. If
separated completely, the transfer guide
would be charged, soiling the transfer guide
and ultimately soiling the back of copy paper.
2. COPYING PROCESS
Transfer guide
2–5