The rotation cycle is measured with reference to the mark provided at the end of the fixing film to rotate the fixing drive motor at the optimum speed, thus keeping

the paper feed speed constant. Measurement of the cycle of each rotation (excluding the initial rotation and post-rotation) of the fixing drive motor starts when 1

second lapses after the motor starts rotating and ends when the trailing edge of the last sheet has passed through the fixing nipper.

[1] Film rotation detection signal (FILM_SENS): Set to 1 and 0 alternately when the fixing film is rotating.

[2] Rotation cycle measurement mark

8.2.2 Controlling the Fixing Film Temperature

8.2.2.1 Outline

The surface temperature of the fixing heater is detected to control the fixing heater drive signal so that the fixing heater temperature becomes the target temperature.

The temperature of the fixing heater is detected by the thermistor (TH1/TH2) provided on the fixing heater. If the surface temperature rises, the resistance of the

thermistor lowers and the voltage of the fixing heater temperature detection signal (M_TH/S_TH) also lowers.

The CPU on the DC controller monitors the voltage of the M_TH/S_TH signal to control the fixing heater 1 drive signal (H1DRV) and fixing heater 2 drive signal

(H2DRV). These two voltages are generated based on the zero crossing detection signal which is output from the heater control circuit. The CPU controls these two

signals to adjust the fixing heater temperature to the prescribed value.

8-2

[3]

[2]

[1]

Fixing film speed sensor

Sub thermistor (TH2)

Main thermistor (TH1)

[2]

J217

[5]

[4]