Color Registration Control - Xerox Phaser 6125 Service Manual

Theory of Operation

Color Registration Control

2-36
High Area Coverage Mode
A continuous printing of any image of area coverage exceeding the toner
dispense capability causes the toner density in the Developer to be lowered.
The High Area Coverage Mode postpones the next page feed and dispenses
extra toner during this time, if the toner dispense time reaches the specified
value during a continuous printing.
Admix Mode
The Admix Mode dispenses toner immediately to prevent the reduction of
toner density, whenever the value of the toner density control patch measured
by the ADC Sensor falls far below the standard value, by dispensing extra
toner. If the toner density level cannot be recovered after this operation, it is
determined that toner has run out.
ADC Sensor Control Function
The ADC Sensor is a reflection type sensor that radiates light from its LED
onto the target and detects the reflected light at its photoreceptor and outputs
electric signals responsive to the amount of the detected light.
To ensure an accurate patch density measurement, the surface of the ADC
sensor is cleaned to remove soil due to toner, etc., and the light amount
adjustment is made so that the reflected light amount satisfies the prescribed
value, when creating the patch for potential control and toner density control.
The printer uses a tandem electro-photographic system with Organic Photo
Conductor (OPC) Drums and direct transfer by the Transfer Belt. Because the
images are formed on the individual Drums of the respective colors and then
overlapped to form one image, a color shift may occur. The color registration
control calculates how much the registration is shifted, and adjusts the Laser
Unit write timing.
The scan control adjusts all four colors in the process direction.
The color registration control is made from a change in inside temperature
and the print count at the execution of the process control. This control is
outlined as follows:
1. With no toner on the Transfer Belt, the output value of the ADC Sensor is
measured to determine the threshold value.
2. The patches for color registration control are generated on the Belt.
These patches are composed of 10 mm lines of K, C, K, M, K, and Y in
this order by the amount of four dispense counts, led by a black trigger.
Phaser 6125/6130 Color Laser Printer Service Manual