Canon iR3570 Series, Service Manual

Page: 394 / 722

Chapter 9
9-2
9.2.2 Down Sequence
0006-6007
iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N / / iR4570N / iR2230 / / / iR3530 /
Down sequence is to prevent the machine from operating when the temperature of the end portion of the fixing film exceeds a specific temperature as when using
small-size paper continuously. The details of the control are described below:
1. The sub thermistor detection temperature is 275 deg C or more.
2. Reduces the number of sheets passed by increasing the paper interval.
3. Returns the number of sheets to the normal when the sub thermistor detection temperature is 265 deg C or less.
9.3 Various Control Mechanisms
9.3.1 Controlling the Speed of the Fixing Film
9.3.1.1 Controlling the Fixing Film Speed in Response to Low Temperature
0006-6037
iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N / / iR4570N / iR2230 / / / iR3530 /
As in the morning, driving the fixing film in a low-temperature environment without warm-up could cause the film to become displaced. In consideration of this
fact, the fixing motor is started up in phases (1/4 speed to 1/2 speed and then to normal speed).
9.3.1.2 Controlling the Fixing Film Speed
0007-5124
iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N / / iR4570N / iR2230 / / / iR3530 /
The rotation cycle of the fixing film is monitored to control the fixing motor to a specific speed.
When the fixing film rotates and, as a result, the reflecting member positioned in the loop of the film approaches the speed sensor, the machine detects the rotation
of the fixing film.
F-9-2
[1]Speed sensor
[2]Reflecting member
[3]Fixing film (driven by fixing motor)
[4]Pressure roller
[A]Paper feed direction
[B]Speed sensor output
[C]1 rotation of fixing film
Timing of Control
The speed of fixing film rotation is monitored at all times after the fixing motor goes on and its speed reaches a specific value. The speed of the fixing motor is then
controlled so that it remains at a specific level at all times.
9.3.2 Controlling the Fixing Film Temperature
9.3.2.1 Controlling the Power Supply in Response to Low Temperature
0007-5125
iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N / / iR4570N / iR2230 / / / iR3530 /
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 mech-
anism 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
0007-5401
iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N / / iR4570N / iR2230 / / / iR3530 /
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 ca-
pability. 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
0006-6583
iR2270 / iR2870 / iR3570 / iR4570 / / iR2270N / / iR2870N / / iR3570N / / iR4570N / iR2230 / / / iR3530 /
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.
[C]
[2]
[B]
[A]
Off
On
[4]
[1]
[3]