Konica Minolta bizhub C250 Service Manual page 135

20. Fusing section
B. Fusing loop control
• By creating a paper loop, the speed difference between the fusing and paper convey-
ance at 2nd transfer part will be adjusted. It prevents the double transferred image or
brush effect.
• The fusing speed is set either to faster or slower than the system speed.
• The fusing loop detect sensor (PC3) checks the shape of a loop between the 2nd trans-
fer part and the fusing roller to switch the motor clock as necessary. Switching the setting
on the motor clock will change its rotation speed as well as the fusing roller's rotation
speed to control how far the paper loop.
OFF
C. Operation flow
1. It starts controlling when the front-edge of the paper reaches to the predetermined
position before the fusing roller.
2. The fusing speed will be low* (-2%) so the paper will create a loop between the 2nd
transfer roller and the fusing roller.
3. When the paper loop more than specified, the fusing loop detect sensor (PC3) will
be ON. The fusing speed will increase when the sensor turns ON. (+2%)
4. When the paper sags less than specified, the fusing loop detect sensor (PC3) will
be OFF. The fusing speed will decrease when the sensor turns OFF. (-2%)
5. Operations explained above will keep the amount of the paper loop within specified
range so the speed difference between the fusing and the paper conveyance for
image transfer will be adjusted.
6. The fusing loop control will finish when the back-edge of the paper passes the pre-
determined position on the back of the transfer roller.
*: The fusing speed will not be low only with the envelopes. (to avoid wrinkles)
102
Theory of operation ver. 3.0 Aug. 2006
ON
Fusing loop detect sensor (PC3)
4038T2C195AA