Epson AcuLaser C8500, Service Manual

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EPSON AcuLaser C8500 Revision C
Operating Principles 2-53
2.7.6 Process Control
In order to conduct consistent printing, parameters concerning image forming
must be corrected at the appropriate time. Control of the entire printing process
including parameter correction control is referred to as “process control.”
Process control primarily consists of the following 3 types of control:
„
Potential control
„
Toner concentration control (PCDC)
„
Toner concentration control (ADC)
2.7.6.1 Potential Control
The proper drum electrification (BCR) voltage and quantity of laser radiation
are needed in order to obtain consistent printing quality. Potential control
controls potential on the drum by measuring by means of the ADC sensor the
developing concentration of the Cin 50% patch of each color (Y, M, C, Bk)
formed on the drum by BCR voltage, quantity of laser radiation, and developing
voltage of differing specifications when printing and the concentration of the
part of the drum not developed, calculating the proper BCR voltage / quantity of
laser radiation, and feeding it back to the HVPS and ROS.
NOTE: Cin 50% patch” is an image alternate development of every 3 dots.
Whether a certain image will be formed with Bk alone or with the 4
colors YMCBk is determined by color mode. In the case of 4 colors
YMCBk, the image is formed in the order of Bk --> Y --> M --> C
two colors per single IBT cycle.
Figure 2-54. Process Control