Canon LBP 2460 Service Manual - Page 57

CHAPTER 2 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 Surface temperature of the upper fixing roller °C Fixing sub heater The center of the upper roller Thermistor Fixing upper roller Drive side Figure 2-2-8 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. 2 - 11