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Mode
Heavy paper 2
Number of sheets passed
Initial rotation temperature
Sheet-to-sheet temperature
Thin paper
Number of sheets passed
Initial rotation temperature
Sheet-to-sheet temperature
Envelope
Number of sheets passed
Initial rotation temperature
Sheet-to-sheet temperature
Transparency
Number of sheets passed
Initial rotation temperature
Sheet-to-sheet temperature
2.6.2.1.2 Fixing Temperature Control
LBP5100
The machine monitors the surface temperature of the fixing heater, and controls the drive signal of the fixing heater so that the temperature will be identical to the
target temperature.
Fixing unit
Thermal fuse (FU100)
Fixing film unit
Main thermistor
(TH1)
The temperature of the fixing heater is checked by 2 thermistors: main thermistor (TH1), sub thermistor (TH2).
TH1 is used for printing temperature detection and sheet-to-sheet temperature control, while TH2 is used to check for edge overheating.
The CPU (IC7) on the DC controller PCB monitors the voltage of these 2 thermistors, and generates the fixing heater drive signal (FSRD) according to the level of
the voltage.
The machine's fixing temperature control mechanism uses the following 5 sequences of operation:
1. Initial Multiple Rotation Temperature Control
The machine executes initial multiple rotation temperature control to prevent tears in the fixing film by melting the grease on the inner side of the film at power-
on for smoother belt movement.
If the reading of the sub thermistor is lower than 55 deg C at power-on, the CPU turns on the fixing heater for a specific period of time before it starts the fixing/
delivery motor.
2. Start-Up Temperature Control
The machine executes start-up temperature control to determine the start-up temperature for the fixing heater to suit the reading of the main thermistor detected
when turning on the heater. If the heater is turned on within 40 sec after the end of the previous print job, the previous printing temperature is used for the
upcoming print job.
3. Printing Temperature Control
The machine executes printing temperature control so that the temperature of the fixing heater will be identical to the target temperature during printing.
In continuous printing mode, the machine changes the target temperature in stages according to the specified number of prints
Temperature
control 1
1-2
165
Printing temperature
170
160
1-5
194
Printing temperature
189
189
1-2
165
Printing temperature
170
160
1-2
170
Printing temperature
175
170
Fixing heater (H100)
Sub thermistor
(TH2)
Temperature
Temperature
control 2
3-6
158
168
158
6-17
174
184
179
3-6
158
168
158
3-6
168
173
168
Zero crossing
circuit
+24V
RL901
Relay drive
circuit
Fixing heater
drive circuit
Fixing control circuit
Low-voltage power supply unit
F-2-37
Temperature
control 3
control 4
7-13
14-25
155
150
165
160
155
150
18-37
38-73
162
156
177
171
172
166
7-13
14-25
155
150
165
160
155
150
7-13
14-25
161
157
171
167
161
157
DC controller PCB
ZEROX
RLD+
RLD-
FSRD
Fixing heater
safety circuit
RLD
SUBTH
MAINTH
+3.3V
Chapter 2
Temperature
control 5
26-
145
155
145
74-
149
164
159
26-
147
157
147
26-
153
163
153
0015-9294
IC7
CPU
+3.3V
2-33
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