October 2012
8-23
ColorQube 8570/8870 Service Manual
Print Process
Theory of Operation
Xerox Internal Use Only - Revised, 3rd Revision
Printhead
The Printhead is the heart of the printer, spanning nearly the length of the Drum. Using its 1236
jet nozzles (309 jets for each primary color), with a horizontal motion of slightly less than 5 mm
(0.2 inches), the Printhead can print the entire image on the rotating Drum. The Printhead pro
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vides one size ink drop that it uses for all print-quality modes.
The Printhead jets receive drive signals from the Wave Amp. The internal Jet Stack Heaters
receive control signals as well as AC power from the Electronics Module. Additional features of
the Printhead include the Lift Handles, Purge Tube, and head-to-drum contacts.
Figure 5 Printhead Components
The Printhead’s Jet Stack is fabricated from a stack of chemically etched steel plates which are
brazed together to form the jet array. Channels formed by the stacked plates route ink past the
1236 individual, piezo-electric crystal-driven diaphragms, which force the ink in droplets out the
1236 corresponding nozzles. Looking at the Printhead face, the nozzles are arranged in 12
rows, in color order KYKYKYCMCMCM, where K = black, Y = yellow, C = cyan, and M =
magenta. During the printing process, the Printhead would only have to travel approximately
14 pixels horizontally to provide complete coverage. However, the Printhead travels much fur
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ther, depending on print resolution, to interlace each jet with the output of neighboring jets.
The jet array is bonded to a cast aluminum ink reservoir. The reservoir supplies the molten ink
to the jet array. Heaters in the reservoir and the jet array keep the ink in a liquid state.
Figure 6 Printhead Detail
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General
Weight and Dimensions
