Canon iR3245, Service Manual

Page: 286 / 746

Chapter 9
9-4
9.3.2.3 Controlling the Power Supply at Start-Up
0018-9778
iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The start-up power supply control is performed to the fixing heater (H1/H11, H2/H12) so as to raise the temperature of the fixing assembly to the required temper-
ature for fixing in a short time.
In the fixing heater, the heater resistor value varies according when a temperature increases. For a quick and smooth temperature increase, it is necessary to adjust
the input voltage and control the power.
Due to the foregoing mentioned conditions, in the mechanism of start-up power supply control, a power supply ratio of the fixing heater is corrected according to
the temperature detected by the fixing thermistor and the volume of changes.
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.
F-9-3
A: start-up control
B: copying temperature control
C: 65 (%) power supply
D: X (%) power supply
E: Y (%) power supply
9.3.2.4 Copying Temperature Control
0018-9779
iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
This machine performs copying temperature control to control the temperature of the fixing heater (H1/H11, H2/H22) to an optimum level while paper is passing
through the fixing film assembly.
When the temperature detected by the fixing thermistor (TH1, TH2) is higher than the target control temperature for a specific period of time (0.6 sec) or more, the
machine decreases the power ratio. When lower, it increases the power ratio.
9.3.2.5 Changing the Fixing Film Control Temperature
0018-9780
iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
When a fixing failure occurs or creases appear, the fixing film control temperature can be changed in the service mode as shown below.
9.3.2.6 Temperature Control in Response to Automatic Double-Sided Copy
0018-9781
iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The second side of an automatic double-sided copy requires lower control temperature in comparison with the first side. For this reason, the control temperature is
lowered for the second side of an automatic double-sided copy so as to prevent adverse effects such as rises in temperature.
9.3.2.7 Temperature Control in Response to Change of Paper Size
0018-9783
iR3225 / iR3225N / iR3235 / iR3235N / iR3245 / iR3245N
The machine has a function to switch the paper size during continuous mode such as in rotation sort. When small-size paper is generated continuously, the temper-
ature of the end portion of the fixing film rises. Immediately thereafter, if large-size paper is passed, high-temperature offset might occur at the end portion where
the temperature is likely to have risen. To prevent high-temperature offset, the control temperature is changed when the paper size changes.
Service mode:
COPIER> OPTION> BODY> TEMP-CON (to switch the fixing temperature mode for heavy paper)
COPIER> OPTION> BODY> TEMPCON2 (to switch the fixing temperature mode)
0: OFF (default), 1: -10 deg C, 2: -6 deg C, 3: -3 deg C, 4: +3 deg C, 5: +6 deg C, 6: +10 deg C, 7: 15 deg C
Start-up control
target temperature
85
400ms
500ms
200ms
300ms
A
B
C
D E