Fusing - Kyocera Mita FS-6750 Service Manual

Operation theory
Electrophotographics system
Since a paper is charged in negative by the high-pressure bias at the time of trans-
fer, as for a paper, after transfer sticks to a drum electrically. For this reason, the
seal of approval of the positive high pressure contrary to transfer bias is carried out
to separation electrodes, neutralize electrification on a paper, a paper is made to
separate from a drum compulsorily, and conveyance is made possible. By choosing
paper thickness by the front panel, the voltage by which a seal of approval is car-
ried out to separation electrodes can choose the optimal separation bias automati-
cally.
+
B
A
-
+
The nominal transfer bias is set to approximately -1.80 kV (limit) with the current
2
of 15 µA. Since thicker paper (91 to 200 g/m ) such as postcards, OHP, envelopes,
etc., tend to require more bias potential for the satisfactory transferring process,
the transfer bias is user-switchable to 2.8 kV (limit) by using the printerís operator
panel. Double-sided printing using a DU-25 duplexer automatically increases the
transfer bias to the above value.

Fusing

The toner on the paper is permanently fused onto the paper as it passes between
the florin-finished heat roller ("A" below) and the pressure roller ("B" below) in the
fuser unit. The toner is molten and pressed into the paper. The heat roller has a
halogen lamp, turning frequently on and off to maintain a preheat temperature at
approxi-mately 175 °C.
The heat roller temperature is constantly monitored by the engine control circuit
us-ing a thermistor. For safety against overheating, the fuser system is protected
by a triac which automatically opens power to the halogen lamp. If the temperature
ex-ceeds 350 °C, it activates the thermo-cut device to interrupt open power to the
halo-gen lamp.
4-10 FS-6750