Image Processing Reference
In-Depth Information
charging of the other side of the particle layer. If V
r
¼ r
0
d
2
=
the space charge
potential across layer 2, then for a constant density case, the transfer ef
eðÞ¼
2
ciency
equation becomes
V
a
V
r
2D
1
D
2
þ
F
¼
1
for
1
(
10
:
45
)
2D
1
þ
D
2
þ
D
2
V
a
=
V
r
2D
1
D
2
þ
V
a
V
r
2D
3
D
2
þ
F
¼
1
for
1
1
(
10
:
46
)
2D
V
a
V
r
2D
3
D
2
þ
F
¼
for
(
:
)
0
1
10
47
Thus, from these equations, we can
find the transfer limits. The transfer begins (i.e.,
at F
¼
0) when the applied voltage is equal to
2D
3
D
2
þ
V
a
¼
V
r
(
:
)
1
10
48
and complete transfer occurs (i.e., F
¼
1.0) when the applied voltage is equal to
2D
1
D
2
þ
V
a
¼
V
r
1
(
10
:
49
)
These results were compared to experimental data in a laboratory setup. We show the
use of this model for one of the EP transfer system below.
One of the dielectrics in the EP system is the plain paper and the other is the
photoconductor. The particle layer is the layer of image surface carried by the toner
that is crammed between the paper and the photoconductor. For complete transfer
from the photoconductor surface to the paper, the transfer ef
ciency equation can be
written with respect to key parameters of the xerographic transfer system and the
transfer voltage.
The space charge density (
r
0
) of the toner layer is given by [9]
Q
M
p
R
(mC=cm
3
)
r
0
¼
pd
t
¼
3
s
(
10
:
50
)
d
where
p is the packing fraction of the toner (p
¼
0.5 for most toners)
cm
3
]
=
d
t
is the toner mass [mg
M
d
Q
m
=
gr], which is related to the
tribo shown in Equation 10.31 with a simple linear relation of the form
is the toner tribo on the photoconductor [
C
d
¼
c
Q
Q
M
(
10
:
51
)
M
due to time decay of the tribo
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