Paper Tension Mechanism - Epson Stylus Pro 5000 Service Manual

Stylus Pro 5000

PAPER TENSION MECHANISM

During printing, the sheet of paper is bent around the sub roller and held
in place by the PF support roller (1). The sheet straightens out suddenly
when the trailing edge is released. In older printers, such as the Stylus
Color 1520 and Stylus Color 3000, this sudden movement could distort
the print job. The Stylus Pro 5000 has a mechanism to keep constant
tension on the paper above the platen, preventing any sudden motion.
The paper feed support roller is raised and lowered by the sub roller
driver gear train. The pump/ASF motor drives the cam gear. The cam
gear drives a transmission gear, which raises and lowers the paper feed
support roller.
Sub Roller Driver Gear
Sun Gear
Figure 2-25. Sub Roller Driver Gear Train
The sub roller can rotate in only one direction. The pump/ASF motor
drives the sub roller driver gear through two planetary gears. If the
pump/ASF motor rotates in the other direction, it drives the cam gear but
not the sub roller driver gear. There are no teeth along part of the cam
Cam Gear
Planetary Gear
gear's circumference to keep the paper feed support roller from being
raised or lowered too far.
Figure 2-26 shows how the pump/ASF motor drives the paper feed
support roller. The cam gear rotates to raise and lower the paper feed
support roller. When the pump/ASF motor rotates in one direction, the
sub roller turns, and the cam gear raises the paper feed support roller.
When the pump/ASF motor rotates in the other direction, the planetary
gear in Figure 2-25 doesn't engage the sub roller driver gear. The sub
roller doesn't turn, and the cam gear lowers the paper feed support roller.
Table 2-4 shows the relation between the rotation of pump/ASF motor
and operation of each mechanism.
Cam for driving Paper Feed Support Roller
Transmission Gear 1
Transmission Gear 2
Cam Gear
Figure 2-26. Driving the Paper Feed Support Roller
Chapter 2 Operating Principles
Sub Roller
Paper Feed Support Roller
2-16