Atvc (Auto Transfer Voltage Control) - Konica Minolta bizhub c450 Service Manual

Theory of Operation Ver. 1.0 Mar. 2005
14.3.5

ATVC (Auto Transfer Voltage Control)

• To optimize image transfer output, the machine is provided with ATVC control, or Auto
Transfer Voltage Control. The control lets a constant current flow through each of the
Image Transfer Rollers. Then, from the voltage detected, the resistances of the 1st
Image Transfer Roller, 2nd Image Transfer Roller, and Transfer Belt are measured. The
optimum image transfer output voltages applied to the 1st and 2nd Image Transfer Roll-
ers during printing are thereby automatically adjusted.
A. Overview of ATVC operation
Output a constant current to the 2nd
Image Transfer Roller.
Measure the resistance value of the
2nd Image Transfer Roller.
Determine the 2nd image transfer
output voltage.
Output a constant current to the 1st
Image Transfer Roller.
Measure the resistance value of the
1st Image Transfer Roller.
Determine the 1st image transfer
output voltage.
2nd Image Transfer Current Feedback Terminal
B. 1st image transfer ATVC operation
1. The 1st image transfer constant current for each color of toner output from the DC
power Supply/1 is fed back to the DC power Supply/1 via the 1st Image Transfer
Roller, Transfer Belt, and PC Drum ground. This allows the resistance of the Trans-
fer Belt to be measured.
A common ATVC is set for Y, M, and C.
2. The measured resistance is used as the basis for determining the optimum 1st
image transfer voltage for each color of toner.
C. 2nd image transfer ATVC operation
1. The 2nd image transfer constant current output from the DC power Supply/1 is fed
back to the DC power Supply/1 via the 2nd Image Transfer Roller, Transfer Belt,
and Transfer Belt Drive Roller. This allows the resistance of the Transfer Belt to be
measured.
2. The measured resistance, together with the type of paper, temperature and humid-
ity, and the color or monochrome mode 1st side/2nd side, is used as the basis for
determining the optimum 2nd image transfer voltage.
Constant Voltage
Constant
Measured
Resistance
Current
Value
2nd Image Transfer Roller
Transfer Belt
Transfer Belt Drive Roller
4037T2C574AA
14. Transfer Corona section
HV1
Constant
Current
1st Image Transfer Roller
Transfer Belt
PC Drum Ground
53