Barcode Printing FAQs
Different combinations of bars and spaces are used to encode
characters into bar codes. Differences in light and dark and the width
of the elements are the variables used for encoding. The bar code
reader illuminates the symbol and measures the amount of light that is
reflected back. The reader determines the pattern of light and dark or
wide and narrow, then compares it to the encoding table for that type
of bar code (called a symbology) and decodes the symbol.
Hundreds of bar code symbologies have been created, but less than
two dozen are widely used. Each symbology has its own pattern of bars
and spaces and its own rules for encoding data. There are two basic
types of bar codes: linear and two-dimensional (2-D).
Linear codes encode data in bars and spaces in a single line. The U.P.C./EAN symbol is the best-known example of a linear bar code.
Two-dimensional codes encode data in an additional dimension. The two principle types of 2-D codes are stacked and matrix symbologies. Stacked symbologies resemble multiple linear symbols stacked on top of each other. Matrix symbologies feature blocks or lines in a grid or geometric pattern. There are also hybrid 2-D symbologies and other variations.
Symbologies differ primarily by the type and amount of data that
they can hold. Some symbologies offer full alphanumeric encoding,
while others only encode numbers. Symbologies may be fixed or variable
length. However, size isn't unlimited, because the symbol must remain
compact enough to be recognized by the reader. Two-dimensional
symbologies can hold significantly more data than linear codes.
The variety of bar code formats available practically ensures you
can find a symbology that meets your needs. The most important
variables that determine the optimal symbology are the amount of data
that needs to be encoded, the space available to print the bar code
and the type of data to encode.
Variable-length symbologies can be used to encode only a few
characters, if desired, while 2-D codes encode thousands of
characters. The data capacity of variable-length bar codes is limited
by the size of the symbol, which is in turn limited by the ability of
the bar code reader. For reference, a standard U.P.C./EAN symbol
encodes 14 numeric digits. Many bar code applications in warehousing,
distribution, manufacturing, and inventory control require a serial
number of similar length, which many common symbologies can easily
encode into a compact symbol.
Yes. Bar code readers support multiple common symbologies.
Generally, readers can recognize more linear than 2-D symbologies, but
often support a few common 2-D formats. Symbology support varies by
reader manufacturer and model.
Readers have a feature called autodiscrimination, which detects the
symbology that is being processed and decodes it accordingly.
Autodiscrimination enables readers to map the combination of bars and
spaces to the correct character, thus preventing reading errors. Bar
code data entry is extremely accurate, with an error rate estimated at
one error per more than 3 million characters.
Thermal bar code label printers support multiple symbologies.
General-purpose laser and inkjet printers and software applications
may not be able to natively print any bar codes or may not offer
multiple symbologies. Printer specifications list symbologies that are
U.P.C. and EAN bar codes are part of the EAN.UCC system, which is
managed by the Uniform Code Council in the United States and EAN
International in the rest of the world. Visit their Web sites for
details and resources to get started with U.P.C./EAN labeling.
To print bar code labels, a label format must be created with
software that supports bar coding. To print bar codes on documents or
reports, the application software needs to support bar coding or
additional programming will be required. After the label or form is
designed, it needs to be output on a printer that is capable of
producing bar codes and supports the specific symbology that is used.
Because data is encoded using differences between light and dark (and
narrow and wide) elements—which are measured in mils, or thousands of
an inch—a good quality printer is essential for producing crisp lines
and accurate, readable bar codes. Finally, the media must support bar
code print quality by not bleeding, running, fading, or otherwise
defacing the symbol.
Many common laser and ink jet printers are capable of producing bar
codes, but need to be set up to do so. They often do not have native
support for bar code symbologies and need to be upgraded with
additional fonts or programming to support bar coding. They also lack
many of the special features that provide excellent bar code print
quality. For more information about the benefits that bar code
printers provide and to help determine if your operations need them,
see Zebra's white paper "Best
in Class Bar Coding: The Business Case for a Dedicated Thermal Label
Bar code printers are available with many common interfaces to
facilitate simple integration with a variety of host computer systems.
Ethernet, USB, parallel, serial, twinax, and coax cables are
available. Bar code printers also offer 802.11b and Bluetooth
connectivity for wireless integration. Management tools enable remote
monitoring, configuration, and troubleshooting for networked
Zebra also offers many advanced connectivity features. These include embedded XML processors that enable printers to decode and process incoming XML data streams, interfaces for direct connectivity to SAP and Oracle enterprise resource planning systems, solutions for the IBM midrange (AS/400 and iSeries) environment and more.
Many companies require their suppliers and other trading partners to
include a bar code or radio frequency identification (RFID) label on
shipments, which is used to sort incoming materials and manage
inventory to support the company's automated systems. Labels produced
to meet trading partner requirements are called "compliance
labels" because the shipping organization applies the label to
comply with a request or demand. Compliance labels usually must follow
strictly defined formats for layout, content, bar code symbology,
print quality, etc.
First, find out which of your facilities and production or packaging
lines will be impacted in order to determine the required label volume
and the number of printers that will be needed. Determine how the
printers will receive the variable information they need from your
enterprise system to produce the labels. This step will show the
connectivity and networking support required in the printer. Review
the compliance specification to understand the required label sizes,
fonts, bar code symbologies, and graphics so you can choose an
Software is also required to design the label formats. Many bar code and RFID label design packages include templates for compliance label formats commonly used in the retail, automotive, aerospace, defense, distribution, and other industries. Make sure the software supports the types of labels you need and the specific model of printer you have chosen. Test the entire system and send label samples to your trading partner for analysis prior to your deadline date for compliance labeling. Many systems integration companies are very experienced with compliance labeling systems and are available to assist with any phase of the project. Zebra's white paper "Quality Assurance Steps for Preventing Label Printing Problems" explains how to meet print quality requirements for compliance labeling.
Yes, but be prepared to deal with excessive material waste and
printer wear, potential jamming caused by the label adhesive, limited
symbology and software support, and delays while media is changed to
support label or document printing.
Narrow the field significantly by determining the size of labels
that need to be printed. Analyze the conditions the label will be
exposed to and its required life span to determine the print method
(direct thermal or thermal transfer) and required media support.
Printers also differ significantly in the interfaces and network
connectivity that they offer. The symbologies, graphics, and
international characters supported are other important
differentiators. Durability and printing volume are also important.
For most applications, 203 dots-per-inch (dpi) resolution provides
sufficient print quality. However, when higher quality printing is
required, such as for very small labels or some 2-D symbologies, 300
or 600 dpi printers should be used.
Zebra's partners can help you find the right printer for your needs. Find a Zebra reseller.
Yes, but the print speed listed in the printer specifications (which
is expressed as inches per second, or ips) does not always give a true
indication of how fast the unit will print. Some printers take a long
time to process the label format before they start printing.
First label out refers to the time it takes from when the print command is sent until the first label in a print job comes out of the printer. First label out time depends on the label size and the printer's processing power, the interface with the computer system, and the software used in the application. These factors may also result in pauses between labels that prevent full-speed, continuous printing.
Throughput is a truer measure of how quickly a printer can process a complete print job. First label out and throughput can be evaluated when printers are set up for demonstrations or trials. It is important to use the printer in your actual work conditions to determine if it has the speed and throughput to meet your needs.
There are two thermal printing methods commonly used to print bar
codes: direct thermal and thermal transfer. Each method uses a thermal
printhead that applies heat to the surface being marked. Thermal
transfer printing uses a heated ribbon to produce durable,
long-lasting images on a wide variety of materials. No ribbon is used
in direct thermal printing, which creates the image directly on the
label material. Thermal transfer printers can accept a wider variety
of materials and are usually used for permanent or long-lasting
labeling applications. Direct thermal printers are usually used to
produce shipping labels, picking/putaway labels, receipts, and other
common print jobs.
Besides a wide variety of label materials, bar code printers can also print on tag and ticket stock, wristbands, polyester, polypropylene, and other synthetic materials. Different colors are available, but color should be used cautiously because insufficient contrast between bars and the background space will produce unreadable bar codes. Brand protection media is available with overt and covert security features for authentication, counterfeit and diversion deterrence, and secure data encoding. Label media, coatings, and adhesives provide resistance to temperature extremes, moisture, acids, washes, UV exposure, and other hazards to label quality. Thermal printers can also print and encode smart labels, which contain a radio frequency identification (RFID) chip and antenna inlay embedded within the label media.