Purge Unit - Pitney Bowes DM300c Service Manual

3 • Theory Of Operation
3.5 Ink System
3-26

Purge Unit

The purge unit is designed to
maintain good print quality. It
is a totally self-contained unit
(no external pumps or other
components) that is cantile-
vered off the right side plate
and located midway beneath
the print carriage rails.
As shown in the figures, right,
the purge unit has a motor,
pump, capping station, wiper,
print lock and carriage home
sensor.
Motor. When the purge
motor turns counterclock-
wise, it drives the pump
cap, wiper and print lock
through cams; when it
turns clockwise, it drives
the purge pump, also
through cams.
Pump. The pump per-
forms the purge cycles
described in Table 3-2.
Purge cycles are per-
formed when the carriage
assembly is in the home
position and also during
printing. Excess ink from
the purge cycles is de-
posited in the waste tank
as described in paragraph
3.5.5. The system keeps
a log of the number of
purges and tracks the dot
count to determine the
status of the waste tank.
Capping Station. The
print head cap keeps the
print head nozzles from
drying out. The print head
is capped when the car-
riage assembly is in the
home position.
Wiper
Motor Gear Cam Gears
Figure 3-26 Purge Unit, Right Side
Carriage
Home
Sensor
Figure 3-27 Purge Unit, Rear View
Figure 3-28 Purge Unit PCB
DM300c/DM400c/DM475 Service Manual (SV61801 Rev. D)
Carriage Home Sensor
Print head Lock
Capping
Station
Purge
Pump