Phaser 6121MFP Service Manual 2-41
Theory of Operation
developing bias voltage is established that prevents leak image or uneven
density.
• IDC Sensor intensity control
Adjustments are made to correct changes in IDC Sensor characteristics due to
changes over time or contamination. The IDC Sensor is a photo-reflective
sensor that emits light from an LED and detects the reflected light returning
from the Transfer Belt. The light emitted from the LED is controlled so that the
reflected light density is constant.
• Reflectance measurement control
The reflectance of the Transfer Belt is measured using the IDC Sensor. The
measurement is taken for one complete revolution of the Transfer Belt. The
measured value is corrected during the intensity adjustment and G-correction
control.
• Toner adherence control
The developing bias voltage value is adjusted to keep constant the amount of
toner sticking to the surface of the Drum with reference to the 100% solid
image.
• Laser intensity adjustment control
Characteristics of the Drum, developing, and charging processes are affected
over time and by the environment. The intensity of the laser light is adjusted
so that fine lines and gradations of a predetermined level are reproduced at
all times.
• G-correction control
A gradation pattern is produced on the surface of the Transfer Belt. The IDC
Sensor measures the density of the pattern and sends the measured result to
the controller for gradation adjustment.
s6121mfp-147
IN
OUT
Grid Bias Developing Bias
Developing
Charging
PC
ADC Sensor
Temperature/
Humidity Sensor
ADC Control
1st Transfer Roller
2nd Transfer Roller
ATVC
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