Transfer (Step 5) - Canon NP6330 Service Manual

CHAPTER 1 GENERAL DESCRIPTION
During copying, toner is attracted to the photosensitive drum by the work of the drum
surface potential and the developing bias (at time of positive component), turning the
static latent image into a visible image. Excess toner is drawn back from the
photosensitive drum by the work of the drum surface potential and the developing bias
(at time of negative component).
AC bias (frequency, in particular) mainly affects gradation, i.e., the lower the
frequency, the better the gradation; however, such tends to cause fogging. DC bias
mainly affects copy density and fogging; a higher bias, i.e., closer to 0 V, increases
image density but tends to cause fogging.
G. Transfer (step 5)
A negative corona charge is applied to the back of the copy paper, causing the toner
on the drum to move to the copy paper.
The transfer guide and vertical pass upper guide is grounded through a varistor to
prevent soiling of the back of the copy paper and to prevent poor transfer.
Reference:
If the transfer guide and the vertical path were grounded, the charges which should
be on the back of paper would escape through the paper, causing transfer faults. If
they were fully separated, on the other hand, the transfer guide would be charged,
ultimately soling the back of the transfer guide with toner.
1-26
DC bias
Figure 1-610
Copy
paper
Figure 1-611
COPYRIGHT © 1997 CANON INC.
Positive
component
0 V
Negative
component
Transfer
guide plates
CANON NP6330 REV.0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)