Xerox Phaser 6120 Service Manual page 255

ATVC (Auto Transfer Voltage Control)
The ATVC, or Auto Transfer Voltage Control, is for optimizing the transfer output. A constant
current is made to flow through each of the Transfer Rollers. From the detected voltage, the
resistance of each of the 1st Transfer Roller, 2nd Transfer Roller, and Transfer Belt is
measured. The ATVC then automatically adjusts the appropriate image transfer output voltage
to be applied to the 1st Transfer Roller and the 2nd Transfer Roller during the print cycle.
Overview of ATVC Operation
Apply the constant current the 1st
Transfer Roller
Measure the resistance of the 1st
Transfer Roller.
Establish the 1st transfer output
voltage.
Apply the constant current the 2nd
Transfer Roller.
Measure the resistance of the 2nd
Transfer Roller.
Establish the 2nd transfer output
voltage.
1st Transfer ATVC Operation
1. On the 1st transfer, the constant current for each color of toner output from the High
Voltage Unit (HV) is fed back to the High Voltage Unit via the 1st Transfer Roller,
Transfer Belt, and the Photo Conductor ground. The resistance of the Transfer Belt is then
measured.
2.
Based on the measured resistance value, the optimum 1st transfer voltage is established.
2nd Transfer ATVC Operation
1. On the 2nd transfer, the constant current output from the High Voltage Unit (HV) is fed
back to the High Voltage Unit via the 2nd Transfer Roller, Transfer Belt, and the Transfer
Belt drive roller. The resistance of the Transfer Belt is then measured.
2.
Based on the measured resistance value and in conjunction with the environmental
conditions and print color, the optimum 2nd transfer voltage is established.
Phaser® 6120 Color Laser Printer Service Manual
Constant
voltage
Constant Measure
current resistance
2nd Transfer Roller
Transfer Belt
Transfer Belt drive roller
7-35
Print Engine Theory of Operation
HV
Constant
current
1st Transfer Roller
Transfer Belt
Photo Conductor
ground