Bar code symbols may be produced in a variety of ways: by direct marking, as
with laser etching or with ink jet printing; or, more commonly by imaging or
printing the bar code symbol onto a separate label. For our purposes, the terms
"print" and "printer" refer to the production of a bar code whether the image is
printed, etched, or imaged. The importance of precise bar code printing cannot
be overstated; success of the whole set of integrated technologies that comprise
an entire bar code system depends upon bar code print quality.
Bar code printing applications fall into two categories:
- ON-SITE user-controlled printing and
- OFF-SITE label supplier-controlled printing.
assistance in making the selection between off-site and on-site printing review
the Bar Code Labels - Make or Buy document.
On-site printing generally takes place at or near the point of use. The data
encoded is usually variable, entered by an operator through a keyboard or
downloaded from the host computer. The most common bar code print technologies
for on-site use are:
- Direct Thermal — Heating elements in the printhead are selectively heated to
form an image made from overlapping dots on a heat-sensitive
- Thermal Transfer — Thermal transfer technology uses much the same type of
printhead as direct thermal, except that an intervening ribbon with resin-based
or wax-based ink is heated and transfers the image from the ribbon to the
- Dot Matrix Impact — A moving printhead, with one or more vertical rows of
hammers, produces images by multiple passes over a ribbon. These passes create
rows of overlapping dots on the substrate to form an image. Serial dot matrix
printers produce images character by character; high-volume dot matrix line
printers print an entire line in one pass.
- Ink Jet — This technology uses a fixed printhead with a number of tiny
orifices that project tiny droplets of ink onto a substrate to form an image
made up of overlapping dots. Ink jet printers are used for in-line direct
marking on products or containers.
- Laser (Xerographic) — The image is formed on an electrostatically charged,
photo-conductive drum using a controlled laser beam. The charged areas attract
toner particles that are transferred and fused onto the substrate.
On-site bar code printers come in a range of configurations as well as a wide
variety of technologies. Users’ choices include:
- Large copy-machine-size dot matrix line printers, in-line ink jet printers,
or in-line thermal transfer printer applicators for high-volume
- Desk-top dot matrix, laser, direct thermal, and thermal transfer printers
for variable-demand print jobs
- Wireless direct thermal or thermal transfer printers for portable and field
Clearly, with the staggering range of choices available, users need to
carefully determine their application parameters before going to purchase a bar
On-site printing most often involves purchasing label-design software as well
as printer hardware. Bar code printers come with their own proprietary
programming languages that support all the standard symbologies, and they are
capable of printing simple data-static or serialized bar code labels on their
own. However, labels that require additional formatted text, graphics, or
multiple fields will require a separate label-design software package.
Currently, more than 100 packages exist that are designed for a wide range of
platforms and have a wider range of features. Once the purview of programmers,
label design can now be accomplished by non-programmers via easy-to-use WYSIWYG
Generally speaking, commercial label printers may use flexographic,
letterpress, offset lithographic, rotogravure, photocomposition, hot stamping,
laser etching, or digital processes to produce a consistently higher-grade label
than those labels produced by on-site printers. If the content of the bar code
symbol is known ahead of use, a commercial label supplier is generally the best
choice. However, there are tradeoffs. Commercially supplied labels have to be
ordered, stocked, and placed in inventory. A business with frequent product line
changes and/or label changes will have to weigh its options carefully.