Transfer Unit - Ricoh Aficio FX200 Service Training

Slide 52
5. Engine
More on the Transfer Unit
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.
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Transfer Unit

The transfer assembly consists of the PTL (pre-
transfer lamp) and the transfer roller.
The PTL sends light to the OPC drum.
This lowers the charge on the drum's surface and
improves transfer efficiency.
The transfer roller moves toner from the OPC
drum surface to the paper.
The resistance value of the transfer roller changes due to the
surrounding environment in the room or within the machine.
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.
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