Tektronix PHASER 380, Service Manual

Page: 118 / 346

5-16
Phaser 380 Color Printer
5
Theory of Operation
Drum maintenance tray
The maintenance tray performs two functions. Its primary function is to create
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. An
oil-saturated wick applies the oil. Small valves keep the oil from leaking out of
the bladder prior to the maintenance tray being first installed in the printer. The
drum maintenance tray’s second function is to hold a waste ink liner which
collects waste ink from printhead purges.
Note The oil valves are always open when the maintenance tray is installed
in the printer. The oil can leak out if the printer does not remain level.
Prior to each print, a cam, driven by the process motor, raises the wick against
the slowly rotating drum. A compliant blade, also raised by the same cam,
assures that the oil film is smooth and even across the drum’s surface. As the
drum completes one rotation, the rotating cam lowers the wick and then a
moment later, lowers the blade.
A counter gear slowly and incrementally advances a sensor interrupt flag across
the width of the maintenance tray each time the cartridge is used. When it
interrupts its sensor, it indicates the maintenance cartridge must be replaced.
The sensors are mounted on the inside of the printer frame.
Figure 5-10 The drum maintenance cartridge
Oil on drum
Blade
Counter
gear
Oil bladder
Oil valves
Cam
Maintenance
cartridge
Waste ink
bin
Drum
Wick
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