CHAPTER 2

B. Fixing Control

1. Fixing temperature control

The upper fixing roller contains two heaters: fixing main heater (H1: 600W) and fixing sub heater

(H2: 450W). The fixing main heater heats the center of the upper roller, and the fixing sub heater mainly heats both ends of the upper roller. The figure below shows the light distribution of the heaters.

Surface temperature of the

upper fixing roller

Fixing main heater

°C

Fixing sub heater

 

 

The center of the upper roller

Drive

 

 

 

side

 

 

 

 

Thermistor

Fixing upper roller

 

Figure 2-2-7

The surface temperature of the fixing roller is detected by the thermistor (TH1) on the fixing roller. As the surface temperature rises, the resistance of TH1 decreases, and the voltage of the FIXING ROLLER TEMPERATURE DETECTION signal (FSRTH) lowers.

The CPU (IC201) on the DC controller controls the FIXING MAIN HEATER DRIVE signal (/FSRD1), FIXING SUB HEATER DRIVE signal (/FSRD2), FIXING HEATER DRIVE ENABLE sig- nal (FSRDE), and INVERTER CIRCUIT DRIVE signal (SUPSLT) based on the voltage of the FSRTH signal in order to bring the surface temperature of the fixing roller to the specified value.

This printer sets the TH-L/H signal to "H" when the fixing roller temperature is low (during warm-up) and to "L" when the temperature is high (during normal temperature control) in order to improve the accuracy of the FSRTH signal detection.

Table 2-2-1 shows the fixing roller target temperature during wait, standby, and print peri- ods.

When it receives a /PRNT signal from the video controller, the CPU starts the fixing heater print temperature control. The target fixing temperature and print speed at that point is shown in Table 2-2-1. When you make duplex print or select "ROUGH" in "PAPER TYPE MENU" from the control panel, the target fixing temperature and print speed are different from that of nor- mal printing.

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Canon 3260 manual Fixing Control Fixing temperature control