Drive; Transfer; Fusing - Xerox WorkCentre PE120 Service Manual

4.5.2 Drive

The main motor drives the paper feed, developing unit, and the fuser. It is driven by software which controls the
acceleration, constant speed and deceleration profiles. The motor is managed with an A3977 driver IC and
controlled by step and enable signals from the CPU.

4.5.3 Transfer

The charging voltage, developing voltage and the transfer voltage are controlled by PWM (Pulse Width
Modulation). Each output voltage is changeable according to the PWM duty cycle. The transfer voltage used when
the paper passes the transfer roller is decided by environment recognition. The resistance value of the transfer roller
changes due to the surrounding environment in the room or within the set, this change in resistance in turn changes
the value of the voltage due to loading. This voltage is fed back into the set through the A/D converter. Based on
this fed back value the PWM cycle is changed to maintain the required transfer voltage.

4.5.4 Fusing

The temperature of the heat roller's surface is detected according to the resistance value of the thermistor. The
thermistor resistance is measured using the A/D converter and thus the CPU can determine the temperature of the
heat roller. The AC power is controlled by comparing the target temperature to the value from the thermistor. If the
value from the thermistor is out of the controlling range while controlling the fusing process, the error stated in the
table occurs.
Error Description
Open Heat Error:
When warming up: it has been lower than 68 °C over 25 sec
Lower Heat Error:
Standby: It has been lower than 100°C over 25 sec
Printing: 2 consecutive pages: it has been lower than 145°C over 5 sec, 3 consecutive page: it has been 40°C
lower than the fixed fusing temperature over 4 seconds.
Over Heat Error:
It has been higher than 220°C over 3 seconds.
4.5.5 LSU
The LSU consists of the LD (Laser Diode) and the polygon motor control. When the printing signal occurs, the LD
is turned on and the polygon motor is enabled. When the light sensor detects the beam, Hsync occurs. When the
polygon motor speed becomes a normal, LReady occurs. If these two conditions are satisfied, the status bit of the
LSU controller register becomes 1 and the LSU is judged to be ready. If the two conditions are not satisfied, the
error shown in the table below occurs.
Error Description
Polygon Motor Error:
The polygon motor's speed isn't normal.
Hsync Error:
The polygon motor's speed is normal, but the Hsync signal is not created.
Service Manual
Product Summary
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