Read Sharp MX-1800N (serv.man34) Service Manual online
MX-1800N FUSING SECTION N – 2
2. Operational descriptions
A. Fusing unit drive
To drive the fusing unit, the drive power is transmitted from the
drive motor (FUM) through the connection gear to the upper heat
roller gear.
The drive motor (stepping motor) is driven according to the control
signal sent from the PCU.
drive motor (FUM) through the connection gear to the upper heat
roller gear.
The drive motor (stepping motor) is driven according to the control
signal sent from the PCU.
B. Heater lamp drive
The surface temperature of the heat roller detected by the ther-
mistor is sent to the PCU. When the temperature is lower than the
specified level, the heater lamp lighting signal is sent from the PCU
to the heater lamp drive circuit in the sub power PWB.
The power triac in the heater lamp drive circuit is turned on, and the
AC power is supplied to the heater lamp, lighting the lamp and
heating the heat roller.
To prepare for an abnormally high temperature of the heat roller,
the thermostat is provided for safety.
When the thermostat is opened, power supply (AC line) to the
heater lamp is cut off.
mistor is sent to the PCU. When the temperature is lower than the
specified level, the heater lamp lighting signal is sent from the PCU
to the heater lamp drive circuit in the sub power PWB.
The power triac in the heater lamp drive circuit is turned on, and the
AC power is supplied to the heater lamp, lighting the lamp and
heating the heat roller.
To prepare for an abnormally high temperature of the heat roller,
the thermostat is provided for safety.
When the thermostat is opened, power supply (AC line) to the
heater lamp is cut off.
C. Fusing operation
Color toner of YMCK on paper is heated and pressed by the heat
rollers to be fused on paper.
At that time, color toner of YMCK is mixed to reproduce nearly
actual colors of document images.
rollers to be fused on paper.
At that time, color toner of YMCK is mixed to reproduce nearly
actual colors of document images.
The upper and the lower heat rollers are provided to heat from
above and below.
This is because it is necessary to heat four layers of toner from
above and below and right and left to fuse it on paper.
The upper and lower heat rollers are of silicon rubber.
This is because of the following reasons:
1)
above and below.
This is because it is necessary to heat four layers of toner from
above and below and right and left to fuse it on paper.
The upper and lower heat rollers are of silicon rubber.
This is because of the following reasons:
1)
To provide a greater nip quantity and a higher heating capacity
for paper.
for paper.
2)
The soft, flexible rollers press multi-layer toner without defor-
mation to fuse on paper.
mation to fuse on paper.
3)
An even pressure is applied to an uneven surface of multi-
layer toner.
layer toner.
D. Fusing temperature control
The temperature sensors are provided at the center and the edges
of the upper heat roller, and at the center of the lower heat roller.
The heat roller temperature is detected by the temperature sensors
to control the heater lamp so that the temperature is maintained at
the specified level.
The fusing temperature is switched according to the machine con-
dition and paper type selected.
of the upper heat roller, and at the center of the lower heat roller.
The heat roller temperature is detected by the temperature sensors
to control the heater lamp so that the temperature is maintained at
the specified level.
The fusing temperature is switched according to the machine con-
dition and paper type selected.
HL_US
Heater lamp (2)
Heats the fusing roller (heating).
RTH3
Fusing temperature sensor (3)
Detects the surface temperature of the fusing roller (heating).
HLTS3
Thermostat (3)
Shuts conduction to the heater lamp when the temperature rises abnormally. [For the fusing roller (heating)]
HL_LM
Heater lamp (3)
Heats the fusing roller (heating).
FUM
Fusing motor
Drives the fusing unit.
No.
Name
Function/Operation
1
Fusing roller (Heating)
Heat and presses toner on paper to fuse it on paper.
2
Pawl
Paper which was not separated naturally from the fusing roller (heating) is mechanically separated.
3
Fusing roller (pressing)
Heat and presses toner on paper to fuse it on paper.
Signal name
Name
Function/Operation
FUM
PCU
Mode
Paper
Fusing
roller center
(heating)
main
Fusing
roller
(heating)
sub
Fusing
roller
(pressing)
Ready state
Print mode
Print mode
B/W normal
paper
paper
170
180
130
Color normal
paper
paper
170
180
130
Heavy paper
170
175
140
OHP
170
170
145
Envelope
180
180
145
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