Xerox ColorQube 9303 Series, Service Manual

Page: 1770 / 1812

February 2013
8-76 ColorQube® 9303 Family
Principles of Operation
Figure 25 Drum drive
Drum Encoder
Figure 26 . The drum encoder provides drum position information.
Figure 26 Drum encoder
Cleaning Unit
The function of the cleaning unit is to uniformly apply a thin layer of release agent (silicon oil)
onto the drum’s surface, while clearing the drum surface of contaminants. Prior to imaging, the
drum receives a uniform coating of release agent applied by the cleaning unit roll. The amount
of release agent used is bounded by major failure modes and controlled by the oil metering
blade. If too little release agent is applied to the drum, the ink will not completely transfer and
the print quality will degrade as well as increase the amount of ink that the cleaning unit must
clean off the drum before making the next print. In addition, too little release agent will cause
stripping failures, as the ink will not release from the drum. If too much release agent is
applied, it saturates the paper with release agent and, during duplex printing, prevents com-
plete transfer to the second side of the paper. Once the drum has been coated with release
agent, the roller is moved away from the drum surface to enable the written image to be
formed.
Figure 27 . The cleaning unit utilizes two release agent level sensors; a low sensor consisting of
a hall effect switch on a float and an out sensor that detects the pressure difference when
pumping air instead of release agent. This can occur when the release agent reservoir is
depleted. A software algorithm is used to estimate the amount of release agent remaining in
the cleaning unit based on the amount of paper and ink run through the printer. This algorithm
in combination with the two level sensors and the knowledge of the release agent in the reser-
voir in a new cleaning unit, allows an approximate level sensing ability at all release agent lev-
els.
Once the release agent reservoir is depleted, the cleaning unit can support the printing of sev-
eral thousand additional prints by using the release agent in the cleaning unit roller. All level
sense and life information is stored in an EEPROM inside of the cleaning unit allowing a clean-
ing unit to be moved from machine to machine without loss of information.
The cleaning unit provides approximate ‘percentage of life’ information until the reservoir is
depleted. When the unit can support a further 30,000 A-size prints, the cleaning unit low
release agent state is reported. When the reservoir is depleted, the cleaning unit reports a very
low release agent state and begins an A-size print remaining countdown, starting from 3000
prints. The cleaning unit reorder message will appear based on a calculated number of days
remaining. When the counter reaches zero, the cleaning unit is no longer functional and must
be replaced. The average cleaning unit life is 285,000 prints for the average ink coverage of
11% fill on A / A4 size office media. As ink coverage increases, the cleaning unit life will
decrease. Coated and smooth media will also use more release agent, which also causes the
cleaning unit life to decrease.