Thermal Printer Media - Printronix T4204 Maintenance Manual

Chapter 1
About The Printer
The Printing Process
The thermal printhead allows two modes of operation:
•
Direct Thermal Mode—The thermal printhead selectively heats small,
rectangular dots. When the heated dots contact specially coated thermal
paper, the dyes and developers in the coating react to the heat and
develop an image. This mode of printing is often used for short-term
labeling applications.
•
Thermal Transfer Mode—The heated dots contact a thermal ribbon; the
heat reacts with the ribbon and bonds the image to the paper. This
method is used especially for abrasive, long-storage applications and for
specialized applications, such as in extreme environmental conditions or
where tamper-proofing is required.
Dynamic Print Control
Print quality in thermal printers depends on how well the thermal ribbon and
thermal transfer paper respond to the heat of the thermal printhead. The
thermal printhead must reach a set temperature to print, then cool down in the
shortest possible time after printing. Print quality is therefore dependent on
precise control of the energy supplied to the thermal dots. If uneven print
density occurs, it is usually caused by the stored heat from previous dots.
The T4204 printer uses Dynamic Print Control technology to ensure even
print density. Dynamic Print Control is printer software that tracks and adjusts
printhead temperatures. Based on stored results of previously printed dots,
the printer predicts the amount of heat required to print subsequent dots and
regulates the electrical energy applied to the printhead. This prevents uneven
print density and permits the printing of narrow-ladder bar codes and vertical
grid lines that are absolutely straight.

Thermal Printer Media

Because there are two modes of operation, there are two kinds of thermal
printer paper:
•
Direct thermal paper—paper coated with chemicals which act as
accelerators, acceptor dyes, and ink binders. In direct thermal mode, the
heat from the thermal printhead contacts the paper and causes a
chemical reaction to take place.
•
Thermal transfer paper—films or synthetic paper substitutes that
transfer images well and other papers designed to resist scratching. Most
of these papers can be die-cut for easy label applications. Printronix
offers a wide selection of thermal transfer paper sizes and face stocks,
which ensures high print quality and long life when used with Printronix
ribbons.
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