Fixing Control - Canon LBP 2460 - B/W Laser Printer Service Manual

B. Fixing control
1. Fixing temperature control
The upper fixing roller contains two heaters: fixing main heater (H1: 500W) and fixing sub
heater (H2: 500W). The fixing main heater heats the center of the upper roller, and the fixing sub
heater heats both ends of the upper roller. The maximum power consumption is reduced by
controlling the two heaters. Figure 2-2-8 shows the surface temperature distribution of the upper
fixing roller.
The fixing roller heater for the 100V model of this printer is different from that to the 220V
model.
Fixing main heater
Thermistor
a. 100V model
The fixing temperature is detected by the thermistor (TH1) on the surface of the upper fixing
roller. If the surface temperature rises, the TH1 resistance increases, and the voltage of the
FIXING ROLLER TEMPERTURE SENSE signal (FSRTH) decreases.
Based on the FSRTH signal voltage, the microcomputer (CPU) on the DC controller controls
the FIXING MAIN HEATER DRIVE signal (/FSRD1E) and FIXING SUB HEATER DRIVE
signal (/FSRD2E) which maintain the surface temperature of the upper fixing roller at its correct
value.
The CPU controls these signals according to the paper size, thickness, and the pick-up source.
Table 2-2-1 lists the target temperatures of the upper fixing roller during waiting, standby, and
printing.
Surface temperature of the
upper fixing roller
C
The center of the upper roller
Fixing upper roller
Figure 2-2-8
CHAPTER 2
Fixing sub heater
Drive
side
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