Cleaning Mode
If the paper size is smaller than the printed image, or if a paper jam occurs
during printing, toner may be transferred to the the roller surface. To prevent
this toner from transferring to the back side of copies, the transfer roller has
to be cleaned before the next printing run.
While the machine is in the cleaning mode, the power pack supplies -1000V
±
50V to the transfer roller, and charges the drum to -750 V. The negatively
charged toner on the transfer roller is then transferred back to the drum.
The machine goes through the cleaning mode in the following conditions:
•
At power-up (the process starts when the fusing temperature reaches
half of the standby temperature)
•
When the cover is opened and then closed during the printing process.
•
After a printer jam has been cleared.
•
After the bypass feed slot has been used (each page): This is done only
if printer switch 00 bit 3 is set to 1.
The cpu controls the transfer roller voltage through the power pack using the
Transfer 0 and Transfer 1 signals as shown below (for a circuit diagram, see
Bias Control in section 2-2-6).
In
Transfer 0
Low
High
Low
High
Transfer 1
Low
Low
High
High
Out
Transfer Roller
+ 5
µ
A
- 1000 V
Off
Off
DETAILED SECTION DESCRIPTIONS
May 22nd, 1995
PRINTING
2-48
