Fixing System; Overview; Controls - Canon MF8580Cdw Service Manual

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Technical Overview > Fixing System > Controls > Fixing Speed Control

Fixing System

Overview

The fixing power supply controls temperatures of the Fixing Assembly.
This product employs the on-demand fixing method in the Fixing Assembly. The figure below
shows the structure schematically.
H801
FU1
TH802
HEATER
Fixing film
DRIVE signal
FIXING TEMPERATURE signal
Pressure roller
Name MF8500 MF8200
Fixing heater 100V H100 T801
120V H120
230V H220
Main thermistor TH801 TH802 To detect the fixing heater temperature
Sub thermistor 1 TH802 -
Sub thermistor 2 TH803 -
Temperature fuse FU1
The temperature fuse is attached to the center of the fixing heater.
When the fixing heater comes to be abnormally hot, the temperature fuse is open to shut off
the power supply to the fixing heater.
The thermistor detects the fixing heater temperature to input the temperature detection signal
to the DC controller. Note that temperatures at heater ends are not detected in models of
MF8200 series with slower print speed.
The temperatures in the whole fixing assembly are controlled by the fixing control circuit and
the fixing heater safety circuit based on commands from the DC controller.
2 Technical Overview > Fixing System > Controls > Fixing Speed Control
Fixing DC controller
power supply
Fixing control
circuit
FIXING
Fixing heater
safety circuit
Role
To heat the fixing film
(center of the heater, contact thermistor)
To detect the fixing heater temperature
(heater ends, contact thermistor)
To prevent abnormal temperature rise in the
fixing heater
T-2-17

Controls

■ Fixing Speed Control
● Reduction of Throughput Based on Detected Temperature of Sub
Thermistor
Paper interval extension time is determined based on the detected temperature of the Sub
Thermistor.
Paper interval extension time determined by the detected temperature of the Sub Thermistor
is added to the paper interval extension time derived from the paper width detection result
and paper length detection result.
Detection of temperature by the Sub Thermistor is performed when the Delivery Sensor turns
OFF.
When the Paper Width Sensor is ON, reduction of throughput based on the detected
temperature of the Sub Thermistor is not executed.
Tempreture of Sub Thermistor: Tx
F-2-32
Note :
• With MF8200 series, this control is not executed since detection of temperature by the
Sub Thermistor is not performed.
• Tempreture of Sub Thermistor: T1 < T2 < T3 < T4
Paper interval (sec)
T1 3
T2 6
T3 9
T4 15
T-2-18
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