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Chapter 2
2.8 FIXING UNIT/DELIVERY SYSTEM
2.8.1 Overview/Configuration
2.8.1.1 Outline
The fixing/delivery unit fixes the toner onto a print paper and delivers it to the delivery tray.
The operation of the fixing/delivery unit is explained in the following.
1) The print paper fed from the pick-up/feed unit is fused the toner by the fixing film and the pressure roller.
2) The print paper delivered from the fixing unit is delivered to the face-down delivery tray or the face-up delivery slot.
When the engine controller detects that the heater temperature reaches 55 deg C after the last rotation is completed, it drives the main motor for 100msec. and
dislocates the nip part. This prevents the toner adhering to the pressure roller.
The fixing unit of this printer utilizes the on-demand fixing method. It is structured as shown below.
- Heater:
This fixing unit incorporates one heater.
Fixing heater (H1): To heat the fixing film (ceramic heater)
- Thermistor:
This fixing unit incorporates one thermistor.
Thermistor (TH1): Sit almost at the center of the fixing film. (contact type)
To control the temperature of the fixing film
- Thermal switch:
Thermoswitch (TP1): Sit almost at the center of the fixing film (contact type)
If the temperature of the heater rises abnormally high, the contact gets broken and cuts off the AC voltage supply to the fixing heater to interrupt the power supply
to the heater.
The temperature control of the fixing unit incorporated as above is operated by the fixing temperature control circuit according to the command from the CPU
(IC201) on the DC controller.
The followings describe the each circuit and function of the temperature control of the fixing unit.
Fixing heater
2-22
Thermistor
Fixing temperature
control circuit
Engine controller PCB
F-2-27
Fixing unit
Fixing film
Thermoswitch
Pressure roller
CPU
0011-2486
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