Separation, Transport Section - Sharp SF-2314 Service Manual

2. Separation, transport section

After passing the resist roller section, the paper is transported to the
transfer section. After transfer, the paper is separated from the drum
by the separation electrode and the drum separation pawl, then
transported to the fuser section by the transport belt.
3. Fuser, paper exit section
The toner image transferred on the paper is fused by the heat and
pressure of the upper and the lower heat rollers. After fusing, dis-
charge static electricity on the paper with the discharge brush. Then
the paper is discharged to the copy tray.
•
Temperature control
Thermistor
Heat roller
CPU
Heater lamp
(Heater trouble)
Self diag display
Thermostat
•
Abnormally high temperature (H3)
•
Abnormally low temperature (H4)
•
Thermistor disconnection (H2)
*
When the thermostat contact is open, it is required to press the
reset button in the upper side of the thermostat. (The contact is not
reset automatically.)
Heat roller surface
temperature detection
The heat roller is heated by the
heater lamp.
(When the heat roller surface
temperature is 180 C˚ or lower,
the heater lamp is actuated)
Contact open (*)
Abnormal high
temperature
4. Developer section
4-1. General descriptions
(1) Two-component developer
The developer is composed of toner and carrier.
Carrier serves as a medium for attaching toner onto the electrostatic
image on the photoconductor drum.
By stirring toner and carrier, they are rubbed to be charged positive
(+) and negative (–) respectively.
Since developer will deteriorate to degrade copy quality, it should be
replaced regularly.
(2) Two-component magnetic brush development
The rotatable non-magnetic sleeve is provided over the magnet roller
and is rotated.
Carrier forms a magnetic brush on the sleeve surface by magnetic
force to attach toner onto the electrostatic image on the photoconduc-
tor drum.
(3) Developing bias
When the photoconductor is charged and exposed to light (ex-
posure), the surface potential (voltage) of the photoconductor will not
be lost completely. (The residual potential remains.)
Toner is attracted to the photoconductor by this residual potential,
dirtying the photoconductor. As a result, a dirty copy of white back-
ground is generated.
To prevent against this, a voltage of the same polarity and higher
than the residual potential is applied to the MG roller, preventing toner
from being attached to the photoconductor surface.
MG roller
Toner
Carrier
5 – 2
Residual potential < DV BIAS
DV BIAS
-200V
Developing bias voltage