2-24 Phaser 8400/8500/8550 Color Printer
Drum Preparation
To prepare the drum, the drum maintenance system applies a thin coating of silicone
to the surface of the drum. The process drive first rotates the drum maintenance
camshaft. As the drum rotates, the cams on the ends of the camshaft push against
followers on each side of the drum maintenance system, forcing the oil roller and
blade against the drum. The saturated roller evenly distributes oil on the drum as it
rotates.
Printing
To print, the drum begins to rotates at a speed dependent upon print resolution. As the
drum reaches the correct speed, the jets begin to fire to deposit the image on the oiled
portion of the drum. As the jets fire, the printhead moves from right to left to complete
the image on the drum.
When printing, the printer performs a “six-jet interlace”, in which each jet lays down
a particular number of pixel columns, depending on the print resolution. Each jet lays
down one pixel column for each drum rotation, which varies from eight to 16
rotations, depending on the print resolution. Interlacing “averages out” the variability
between jets as it interlaces each jet with other jets. In some test prints, the printhead
moves to the right and lays down 309 parallel bands of ink. Each band is composed of
15 pixel columns of dots from an individual jet.
Jet substitution allows a better performing jet to be used in place of a missing or
poorly performing neighboring jet. When the printer is in the jet substitution mode,
the printhead makes a second, right to left movement to deposit the pixel columns of
the substituted jets. See "Jet Substitution Mode" on page 6-10.
s8500-016
Drum
Maintenance Roller
Drum Maintenance Pivot Plate
Drum Maintenance
Camshaft
Blade
Oil on Drum
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