| Revision A |
2.1.6.5 Fusing Section
The power from the transport motor (M2) is transmitted to the upper fusing roller so that the
The paper is heated to melt the toner by the upper fusing roller and pressed by the upper and lower fusing rollers. The upper fusing roller is heated by the fusing roller heater lamp (H1) which is built in it. The fusing roller thermistor (TH1) is attached to the upper fusing roller for controlling the heater temperature. Also, the fusing roller thermostat (TH1) and fusing roller heater lamp fuse (TF1) are attached to the upper fusing roller as shown on the next page. The thermostat (TH1) and lamp fuse (TF1) are connected in series to the heater lamp (H1). The heater lamp (H1) is heated when an AC voltage is applied.
Temperature control using the thermistor |
The resistance of the thermistor (TH1) attached to the upper fusing |
roller varies with temperatures. When temperature rises, the |
resistance of the thermistor (TH1) decreases, and vice versa. As |
shown in the circuit diagram, the thermistor output is connected to |
an analog port of the CPU on the main board. |
The input level to the analog port of the CPU decreases as the |
temperature rises. The CPU performs A/D |
conversion for the input level to know the current temperature. |
To heat the upper fusing roller, the CPU set the Heater Remote 1 |
output to ON (“L”) state. Then, the triac on the power supply unit |
turns ON and an AC voltage is applied to the fusing roller heater |
lamp (H1) and the upper fusing roller is heated. The CPU monitors |
the output from the thermistor and controls ON/OFF of the triac to |
control the temperature of the upper fusing roller. |
Thermostat
Thermistor
Temperature fuse
Upper Fusing Roller (Heater Lamp)
Lower Fusing Roller
Paper
When the upper fusing roller temperature becomes abnormal and |
the output from the thermistor lowers than the predetermined level, |
the |
the triac is forcibly turned OFF, resulting in shutting off an AC |
voltage application to the heater lamp. |
Figure 2-26. Fusing Section
Figure 2-27. Temperature Control Using the Thermistor
Operating Principles | Printer Mechanism Operating Principles | 72 |
