Theory of Operation 2-37
Drum Maintenance System
The drum maintenance system creates a thin, intermediate, liquid transfer surface, a
layer of silicone oil, on the surface of the drum prior to printing. The oil keeps the ink
from sticking to the drum’s surface and facilitates its transfer to the sheet of paper or
transparency film. The oil is contained in a porous foam roller.
Prior to each print, the process motor drives a cam to raise the pivot plate, which
raises the oil roller against the rotating drum. The same cam raises the compliant
wiper blade to assure that the oil film is smooth and even across the drum’s surface.
The process drive rotates in one direction. This rotates the drum maintenance
camshaft and raises the drum maintenance system to the drum. The process drive then
rotates in the opposite direction to lower the drum maintenance system. The blade
removes oil and drains it back into the maintenance kit drawer through a felt filter.
The oil roller can then reuse the oil. As the drum completes one rotation, the rotating
cam lowers the oil roller and then lowers the blade.
The drum has a floating deadband, the narrow section of the drum containing excess
oil and other debris. The oil bar is left on the drum surface when the blade is removed
from the drum. This oil bar location is controlled to keep it outside of the print area.
An EEPROM chip, built-in to the maintenance kit, stores the number of oiling cycles
performed by the drum maintenance system. The EEPROM stores the number of
prints remaining to track consumable life. At printer startup, four oiling cycles are
performed to condition the drum.
Drum
Maintenance Roller
Drum Maintenance Pivot Plate
rum Maintenance
amshaft
Blade
Oil On Dru
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