Intermec EasyCoder 301 – Service Manual Ed. 3
32
Chapter 7 Print Unit
7.6
Printhead
Description
The thermal printhead has a density of 8 dots/mm (203.2 dots/inch)
and consists of a substrate on which a line of 832 small resistors are
fitted.
When a current is lead through such a resistor (dot), it is rapidly
heated and can melt the ink on the transfer ribbon or initiate the
chemical process, that produces a black dot in a direct thermal
paper. By synchronizing the paper feed and the heating and cooling
of individual dots, patterns representing text, bar codes and images
will be produced. It is important for the printout quality and the life
of the printhead that the line of resistors is clean, that the energy lead
through the resistors matches the characteristics of the ribbon and/
or paper and that the printhead pressure is correct.
Since the ribbon/paper serves as cooling media for the resistors, it
is important that no resistors outside the paper web are activated, i.e.
that the printer is set up for the correct paper width.
The substrate is permanently affixed to a bracket plate which also
serves as a guide for the transfer ribbon. Do not separate the
substrate from the bracket!
The printhead is connected to J9 on the CPU board by a flat cable
with a 26-p female connector in each end.
