MX-M350/M450 N/U MAINTENANCE AND DETAILS OF EACH SECTION 7 - 22
C. Operational descriptions
(1) Fusing unit drive
To drive the fusing unit, the drive power is transmitted from the
drive motor (MM) through the connection gear to the upper heat
roller gear.
The drive motor DC brushless motor is driven according to the
control signal sent from the PCU.
(2) 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.
Change to : When the triac for the heater lamp circut is turned on
the AC power is supplied to the heater lamp. Heat is supplied to
the roller.
To prevent abnormally high temperatures to the heat roller, the
thermostat is provided for safety.
When the thermostat is opened, power supply (AC line) to the
heater lamp is prohibited.
(3) Fusing operation
Toner on paper is heated and pressed to be fused by the heat
roller.
Code
Signal
name
Name Type Function/Operation
Active
condition
Note
RTH1 RTH1 Fusing temperature
sensor (1)
Thermistor Detects the surface temperature of the fusing roller
(heating). (Center section)
Analog input
RTH2 RTH2 Fusing temperature
sensor (2)
Thermistor Detects the surface temperature of the fusing roller
(heating). (Side roller section)
Analog input
HLTS HLTS Thermostat (1) Opens the circuit to the heater lamp when the temperature
rises abnormally. [For the fusing roller (heating)]
HL1 HL1 Heater lamp (1) Heats the fusing roller (heating).
HL2 HL2 Heater lamp (2) Heats the fusing roller (heating).
MM MM Main motor Drives the fusing unit.
1 Heater lamp 1 Generates heat and transmits heat to the heat roller. The temperature is controlled by the
thermistor. (Generates heat for the upper roller.)
2 Heater lamp 2 Generates heat and transmits heat to the heat roller. The temperature is controlled by the
thermistor. (Generates heat for the upper roller.)
3 Upper heat roller Transmits heat to melt toner on paper and fuse toner by means of a pressure with the lower heat
roller.
4 Lower heat roller Fuses toner on paper by means of a pressure with the upper heat roller.
To improve fusing capability, the diameter is greater than the conventional ones.
(ø30mm→ø40mm)
5 Fusing upper separation pawl Prevents winding of paper around the upper heat roller.
6 Fusing lower separation pawl Prevents winding of paper around the lower heat roller.
7 Thermistor (Center) Detects the surface temperature of the upper heat roller.
(On/off of heater lamp 1 is controlled according to the detected temperature.)
8 Thermistor (Side) Detects the surface temperature of the upper heat roller.
(On/off of heater lamp 2 is controlled according to the detected temperature.)
9 Thermostat When an abnormal temperature of the upper heat roller is detected, the heater lamp power is
interrupted.
To reset the thermoset and close the electrical circuit. Reset the switch on top of the thermostat.
10 Cleaning roller Cleans toner on the lower heat roller. The blast process is employed.
The cold steel roller will attract the unused dirty toner from the pressure roller.
MMPCU
Fusing roller (Heating)
HL2
HL1
---------
Fusing roller (Pressing)
Paper exit
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