Xerox PHASER 6121MFP, Service Manual

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2-40 Phaser 6121MFP Service Manual
Theory of Operation
Process Control
For stable printing, the parameters related to forming both the electrostatic and
toner image are continuously monitored and adjusted by the printer. Parameter
correction and control over the entire printing process is called “process control”.
Two primary process control mechanisms are used by the system, Automatic
Transfer Voltage Control (ATVC) and Automatic Image Density Control (ADC).
Automatic Transfer Voltage Control (ATVC)
ATVC optimizes the transfer output. A constant current flows through each of the
Transfer Rollers. The resistance of each of the 1st Transfer Roller, the Transfer Roller
(sometimes referred to as the 2nd Transfer Roller), and Transfer Belt is measured.
ATVC automatically adjusts the appropriate image transfer output voltage (bias)
that is applied to each Transfer Roller and transfer belt during the print cycle.
Automatic Density Control (ADC)
ADC stabilizes image density to provide accurate tone reproduction. ADC uses the
IDC Sensor and Temperature/Humidity Sensor to monitor system and
environmental parameters to regulate the following:
• Leak detection control
For the clearance between the Drum and Developing Roller, an optimum
Apply The Constant Current To
The 1st Transfer Roller
Apply The Constant Current To
The 2nd Transfer Roller
Measure The Resistance Of
The 1st Transfer Roller
Establish The 1st Transfer
Output Voltage
Measure The Resistance Of
The 2nd Transfer Roller
Establish The 2nd Transfer
Output Voltage
Constant
Voltage
Constant
Current
Measure
Resistance
Constant
Current
2nd Transfer Roller
Transfer Belt
Transfer Belt
Drive Roller
1st Transfer Roller
Transfer Belt
Photo Conductor
Ground
HVPS
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