Transfer Mechanism; Outline; Controlling The Output To Suit The Environment; Transfer Guide Bias - Canon ImageRunner iR8500 Series Service Manual

8.7 Transfer Mechanism

8.7.1 Transfer Guide Bias

8.7.1.1 Outline

iR105i/iR105+ / iR9070 / iR85+ / iR8070
To prevent soiling of the surface of the transfer guide with toner (leading to soiled backs), a bias of the same polarity as toner is applied to the transfer
guide. The transfer guide charging mechanism is controlled for the following:
[1] Transfer guide bias constant voltage
[2] Output to suit the environment
Figure shows the construction of the transfer guide bias
When '1', high voltage output is ready.

8.7.1.2 Controlling the Output to Suit the Environment

iR105i/iR105+ / iR9070 / iR85+ / iR8070
The transfer guide bias is controlled to an optimum level to suit the environment (conditions identified based on data from the environment sensor).
Normally, +600 V is applied to prevent
adhesion of toner to the transfer guide.
Relay PCB
J723
J510A
0 V
1 16
HVDC-EN
2 15
14
3
4 13
5 12
11
6
7 10
When '1', the transfer
8 9
guide bias turns on.
9 8
7
10
11
6
12 5
13
4
14 3
FGD-ON
15 2
FGD-CNT
1
16
'1' : +200V
'0' : +600V
A bias of the same polarity as the toner is
applied in sync with the rotation of the
photosensitive drum.
Normal/low humidity
High humidity
In a high humidity environment, paper tends to absorb moisture
(lower resistance), charging the paper in excess to affect transfer
(faulty transfer); as such, the output is decreased.
1 2 3 4
J733
1
DC 600V/200V
2
Transfer guide
F-8-42
The photosensitive drum is rotating;
yet, paper is not being fed.
Transfer guide bias
Paper passing
+600
+200
F-8-43
Paper being fed
+600
+600
Chapter 8
0006-9737
0006-9742
8-31