Controlling The Fixing Film Temperature; Controlling The Power Supply In Response To Low Temperature; Controlling The Feeding In Response To Low Temperature; Controlling The Power Supply At Start-Up - Canon iR4570 Series Service Manual

9.3.2 Controlling the Fixing Film Temperature

9.3.2.1 Controlling the Power Supply in Response to Low Temperature

iR2270 / iR2870 / iR3570 / iR4570
In a low temperature environment, the heater is supplied with power before the fixing film is driven so as to soften
the grease applied to the fixing film. The mechanism of control is as follows:
If the temperature of the fixing film detected by the thermistor is lower than a specific level, the heater is supplied
with power for a specific period of time before a normal start-up mechanism is initiated.
If the temperature of the fixing film detected by the thermistor is higher than a specific level, the normal start-up
mechanism is imitated.

9.3.2.2 Controlling the Feeding in Response to Low Temperature

iR2270 / iR2870 / iR3570 / iR4570
In a low temperature environment, the feeding timing is changed according to the temperature detected by the
environment sensor so as to enhance the fixing capability. The details are described below.
When the environment sensor detection temperature is 13 deg C or less, the feeding timing is delayed by 5000 msec.
In thick paper mode, the feeding timing is not changed even if the environment sensor detection temperature is 13
deg C or less.

9.3.2.3 Controlling the Power Supply at Start-Up

iR2270 / iR2870 / iR3570 / iR4570
When the thermistor detection temperature is 180 deg C or less, the power control to compensate for the heater,
(varying according to input voltage and a heater resistor value) is performed so as to raise the temperature of the
fixing unit to the required temperature for fixing in a short time.
1. starts 65% power supply.
2. uses thermistor reading = T1 (deg C) occurring 400 msec after the start of 65% power supply.
3)uses thermistor reading = T2 (deg C) occurring 500 msec after the start of 65% power supply.
4. computes the difference between T2 and T1, refers to a power supply ratio table to compute a power supply ratio
X (%), and uses the result.
5. uses the thermistor reading = T3 (deg C) occurring 200 msec after the start of X (%) power supply.
6. uses the thermistor reading = T4 (deg C) occurring 300 msec after the start of the X (%) power supply.
7. computes the difference between T4 and T2, refers to a power supply ratio table, computes a power supply ratio
Y (%), and uses the result.
8. repeats step 5 through 7 until the start-up control target temperature is reached.
9. when the start-up control temperature is reached, shifts to copying temperature control.
Chapter 9
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