Canon MF724Cdw, Service Manual

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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
● Reduction of Throughput by Feeding Small Size Paper
NOTE:
When paper size is specified by user, paper interval is increased from the 2nd sheet of the job.
When a sensor detects that the paper size is small, paper interval is increased from 3rd or 4th sheet of the job.
Based on the combination of detection result of the Pre-registration Detection Sensor and detection result of paper length (L),
paper interval extension time is determined according to the table shown below.
Category Paper type
1 Plain paper (environment temperature is 18 deg C or lower),
heavy paper 1, heavy paper 2
2 Plain paper (environment temperature is higher than 18 deg C), heavy paper 3, label paper
3 Others
Pre-registration Detec-
tion Sensor
Paper length (L) Paper interval extension time (seconds)
1 2 3
ON - 0 (Not extended)
OFF L >/= 270 mm 10 8 6
L < 270mm 8 4 2
■ Fixing temperature control
The fixing control circuit controls temperatures of the fixing heater to attain the respective target temperatures.
The figure below shows this circuit schematically.
MAINTH
/RLD-
FSRD+
RL901
TH
FU1
Fixing heater
safety circuit
DC controller
FU1
䠖
Temperature fuse
TH
䠖
Thermistor
Fixing assembly
ixing heater
drive circuit
Relay
drive
circuit
Fixing control circuit
Pressure
roller
/RLD+
FSRD-
Fuse
FU901
Fixing film unit
The DC controller monitors the fixing heater temperature detection signal (MAINTH) to output the respective fixing heater drive
signals (FSRD+, FSRD-) depending on the detected temperatures. The fixing heater drive circuit controls the fixing heater based
on the output signal to attain the target temperature in the fixing heater.
1. Start-up temperature control
This controls the fixing heater warm-up to the target temperature.
Different temperatures are targeted depending on elapsed time after the last print job, paper types or the environment.
2. Technical Explanation
42