Headlift Mechanism - Intermec EasyCoder PF2i Service Manual

7.8 Headlift Mechanism

Description
Intermec EasyCoder PF2i, PF4i, and PF4i Compact Industrial—Service Manual
The headlift mechanism is used to raise and lower the printhead to allow
media and ribbon load and also to apply a proper printhead pressure
against the media. It works the same way in EasyCoder PF2i, PF4i, and
PF4i Compact Industrial even if some parts in the media compartment
differ. See Chapter 7.1 and the next page for illustrations!
The headlift is operated by the green headlift lever in the print mecha-
nism. The lever is snap-locked at the end of the crank shaft, which runs
inside the pressure shaft. At the other end of the crank shaft and inside the
electronics compartment is an angular plate, which is used by the headlift
sensor to detect whether the printhead is lowered or raised (see Chapter
7.7).
A small eccentrically fi tted knob on the angular plate runs in a crescent-
shaped slot in the lifting arm. A coil spring presses the knob down in the
slot and helps lifting the printhead. The lifting arm is connected by a link
to the pressure link, which pivots in extensions from the center section.
Thereby the rotating movement of the crankshaft is transformed into a
lateral movement.
The upper part of the pressure link is spring-loaded in relation to the
center section. Thus, when the lever is turned towards lowered printhead
position, the pressure is increased. The pressure is factory-adjusted by
means of two screws inside the electronics compartment and fi ne-adjusted
by the operator using a straight-slot screw accessible through a hole in the
center section.
The lifting arm is connected to the pressure shaft by a lever. The pressure
shaft runs through the center section to the print mechanism, where the
pressure arm is fi tted on the shaft. A magnet at the tip of the pressure arm
holds the printhead bracket. The arm can be moved laterally to apply its
pressure at the center of the media, regardless of media width.
The printhead bracket hangs loosely on the pressure shaft in two hooked
"fi ngers." When the printhead is lowered, semicircular guides at both sides
of the bracket engage the inner part of the platen roller and a slot in the
guide link, ensuring that the printhead will be properly aligned with the
platen roller.
When the printhead lift lever is activated from lowered position, the print-
head will not start to move immediately, but the angular plate on the crank
shaft will start to rotate out of the gap in the headlift sensor, indicating a
"printhead lifted" condition. When the lever has reached a more or less
vertical position, a clicking noise will be heard and the printhead is raised
from the platen roller. Now the coil spring between the angular plate and
the lifting arm will help the operator fi nish the movement of the lever and
hold the printhead fi rmly in raised position.
Chapter 7—Print Mechanism
99