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B. Fixing Assembly and
Delivery Unlit
.
1.
Controlling
the Fixing
Roller
Temperature
The upper and lower rollers of the fixing
assembly
and the delivery
roller
of the
delivery
unit are driven
by the main motor
(Ml).
-
The upper roller is heated by a heater
(H1:95OW) built in it.
The DC controller monitors the surface
temperature
of the upper heater by means
of a thermistor
(THl)
so as to control
the
temperature
to a specific value.
The temperature
of the upper
fixing
roller is controlled as follows:
@
For Black Developing
Assembly
,/ --Y
175°C (at standby, during copy
ooeration)
140% (in'pre-heat
mode)
0
ForCTUnit
155°C (at standby, during copy
operation)
140°C (in pre-heat mode)
To prevent drops in the temperature
of
the upper
roller
during
continuous
copy
operation,
the
control
temperature
IS
switched
after 2 copies
for long paper (a,
Table 3-6) and 4 copies for short paper (b,
Table 3-6).
For Black Developing
Assembly
If the copy is narrow (c, Table 3-6) the
control temperature
is 175°C.
If the copy is wide (d, Table 3-6), the
control
temperature
is switched
from
175°C to 165°C.
For CT Unit
If the copy is narrow (c, Table 3-6) the
control temperature
is 155°C.
If the copy is wide (d, Table 3-6), the
control
temperature
is switched
from
155°C to 165°C.
d
A3, B4, A4, 85, 11" X 17", LTR,
Multifeeder
Table 3-6
The copier is equipped with three protection
mechanisms
to prevent the fixing heater
from going ON at wrong timing.
-
The
microprocebsor
monitors
the
voltage of THl
and indicates 'EOOO' or
'EOOl' in response to an error.
l
If the voltage of THl
falls below about
0.9 V (equivalent
of 215"C),
the error
detection
circuit
cuts off the supply
power to the fixing heater regardless
of
the output of the microprocessor.
If the inside temperature
of the thermal
switch rises above 220%
the power to the
fixing heater will be off.
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