October 2012
8-27
ColorQube 8570/8870 Service Manual
Print Process
Theory of Operation
Xerox Internal Use Only - Revised, 3rd Revision
In the Print position (0 degree), the Printhead is forward and resting against the right and left
head-to-drum buttons. The head-to-drum buttons define the space between the jet stack and
the Drum. When the Process Drive is activated, it drives the Drum Maintenance Camshaft to
engage the tilt gear train. The Tilt Cam tilts the Printhead into the Print position. The Cam is
combined with a missing tooth gear that allows the Cam to be inactive in the Print position,
freeing the Process Drive to perform other printer operations.
The Cam has a latching mechanism to unlatch and latch the Head Tilt Gear to engage the
Printhead tilt drive train. The Cam’s latching mechanism also holds the gear in place. A leaf
spring applies constant pressure to engage the gear when the latching mechanism is released.
The arm of the latching mechanism is inside the frame; the rest is visible, outside the frame.
The Head Tilt Solenoid is actuated and deactuated when the Head Tilt Gear rotates to the
respective engaged and disengaged positions.
The action of the Solenoid ensures that the Head-Tilt Gear engages the Tilt Drive Gear.
Through a follower gear, the compound gear drives the Tilt Cam Gear clockwise when viewed
from the Waste Tray slot. A cam follower, mounted on the lower end of the Tilt Arm, follows the
rotating Tilt Cam Gear and tilts the Printhead. After one revolution of the Tilt Gear, the latching
mechanism is pulled back into position by the Head Tilt Solenoid.
Figure 13 Head Tilt Gear Detail
Drum Assembly
The Drum Assembly and Transfix System form the key portion of the printer where imaging
takes place. The Drum Assembly and Transfix System are separate, but interrelated. This sec
-
tion discusses the Drum Assembly. The next section goes into more detail on the transfix sys-
tem.
The Y-Axis Motor rotates the Drum Assembly. The Drum only rotates forward. A drive belt con-
nects between the Y-Axis Motor and Drum pulley. A closed-loop servo drive system is used to
maintain a constant rate of Drum rotation. This system increases the Y-Axis Motor drive current
to compensate for conditions that could slow down the Drum, such as thicker media.
In operation, the image to be printed is formed on the rotating Drum. The Preheater heats the
media to prepare it for image transfer. The heated media is then passed between the Drum
(now rotating much more slowly) and the Transfix Roller. Under the pressure between the
Drum and the Transfix Roller, the image is transferred. An encoder disk and Sensor on the left
end of the Drum monitors the Drum’s speed and position.
Figure 14 Drum Assembly
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General
Weight and Dimensions
