Intermec EasyCoder 301 – Service Manual Ed. 3
25
Chapter 7
7. Print Unit
7.1
Description
The print unit features an 8 dot/mm (203.2 dots/inch) thermal
printhead. The printhead substrate is permanently attached to a
bracket plate. The rear part of the bracket is engaged to a profile
protruding from the centre-line wall.
The front part of the printhead is pressed against the platen roller by
two adjustable knobs. By turning the knobs, the pressure can be
increased or decreased separately on each side of the printhead, so
a proper and even pressure across the paper can be obtained.
By means of a handle, the knobs can be rotated away from the
printhead bracket and the printhead is lifted by a simple spiral
spring. The shaft goes into the electronics compartment and through
the CPU board, where an optical sensor detects whether the
printhead is lifted or lowered.
The platen roller is fitted in permanently lubricated bronze bearings
on walls protruding from the bottom plate. The roller shaft runs
through the centre-line wall and into the electronics compartment,
where it is driven by the stepper motor via a belt-and-pulley
arrangement. In the LinerLess model, the platen roller is made of a
material that prevents the adhesive to stick to the roller.
Underneath the rear part of the printhead is the ribbon/media sensor
(also see chapter 6.4), which controls the paper feed by detecting
gaps or black marks on the paper web.
At the extreme front of the print unit is either a tear-off edge, which
is used to tear off the paper or to separate labels from the backing
paper (liner) in case of peel-off operation (standard model), or a
specially non-stick coated paper guide (LinerLess model).
Printhead Handle
Adjustable Pressure Knobs
Printhead w. Bracket
Spring
Tear-Off Edge
or
Paper Guide
Ribbon/Media Sensor
(hidden)
Platen Roller
