Sharp AR-BC260 Service Manual page 39

(3) Major parts/signals functions and operations
2
6
3
1 2
No. Name
1 Heat roller
2 Upper/lower separation pawls
3 Heater lamp
4 Thermistor
5 Thermostat
6 Paper exit sensor
RW Control signal
RW Control signal
RW Control signal
RW Control signal
RW: Abbreviation of Related Wiring, which means the said load is specified in the related figure of the mechanical and the electrical sec-
tions.
(4) Operational descriptions
a. Fusing unit drive
To drive the fusing unit, drive power is transmitted from the drive
motor (FUSM) through the connection gear to the upper heat roller
gear.
The drive motor (stepping motor) is driven by the motor drive IC in
the driver PWB according to the control signal sent from the PCU.
Driver
PCU
PWB
b. Heater lamp drive
The surface temperature detected by the thermistor is sent to the
PCU. When the temperature is lower than the specified level, the
PCU sends the heater lamp lighting signal to the heater lamp drive
circuit in the DC power PWB.
The triac in the heater lamp drive circuit is turned on to apply AC
power to the heater lamp, which turns on to heat the heat rollers.
The thermostats are provided as a safety measure to prevent
against an abnormally high temperature of the heat rollers.
When the thermostat is opened, the power supply (AC neutral) 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.
5 3
6 4
1 1
6 3
4
Code, Signal name
—
—
Upper: HL1, Lower: HL2
Upper: THSU, Lower: THSD
Upper: HLTS1, Lower: HLTS2
POD1
FUSM_A, A', B, B'
FUCHin
DSWL
HLPR
FUSM
AR-BC260 DESCRIPTIONS OF EACH SECTION 7 - 2
1 1
5
4 6
5
Function
Heats and presses toner to fuse it on paper. Silicon rubber rollers
are used as the upper and the lower heat rollers. Teflon tube is
wound around the upper heat roller.
Mechanically separate paper from the heat roller, which was not
separated naturally.
Heats the heat rollers.
Detects the surface temperature of the heat roller. (Keeps the
roller surface temperature at a constant level.)
Cuts conduction of the heater lamp when an abnormally high
temperature is detected.
Detects paper discharged from the fusing section.
Drives the fusing section.
Fusing unit installation detecting signal
Left cabinet open/close detection signal
Heater lamp power relay (in the DC power PWB) drive signal
The upper and the lower heat rollers are provided to heat from
above and below. This is because it is necessary to heat four lay-
ers 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.
2) The soft, flexible rollers press multi-layer toner without defor-
mation to fuse on paper.
3) An even pressure is applied to an uneven surface of multi-
layer toner.
120V 950W
120V 350W
1 2
4 6