Bar
coding is a technology that has been used for decades. Although the
first major thrust of implementation took place in the retail food industry,
nearly all other sectors are now enjoying substantial benefits. The
successful use of bar coding involves many different ingredients. The
primary objective of the "Ten Key Points of Bar Coding" is to summarize
the various factors into simple, understandable terms. If this foundation
is understood and used properly, there is a very high probability of
successful implementation. These vital tips are based on real world
experiences and will primarily focus on Code 39, Code 128 and U.P.C./EAN
linear symbologies. However, many of these fundamentals will apply to
other linear, two-dimensional and matrix codes.
Use
Lowest Density
The
scanner looks at the pattern of bars and spaces in a similar manner
as the human eye. Wider bars/spaces are easier to interpret and less
subject to hostile conditions like voids and specks of dirt, etc. For
the most effective and reliable scanning, implement with the lowest
possible density. There will be applications that demand the use of
high density media. In these situations, more sophisticated and/or expensive
scanning solutions may be required that will provide satisfactory results. 
Element
Ratio
Every
linear bar code includes a series of narrow and wide bars and spaces
(elements) that make up the final configuration. The difference between
the width of the narrowest and widest elements is the bar code's element
ratio.
Many
bar codes have a 'fixed' ratio, meaning that the width of the wide
elements compared to the narrow ones cannot be changed. Code 128 and
U.P.C./EAN are configured with four specific wide-to-narrow ratios,
so there is no option to change those symbologies.
Code
39, however, does allow the user to control the width of the wide
elements from two times up to three times the width of the narrow
elements.
Although
some Code 39 applications will dictate the use of a low ratio (2:1),
the most effective and reliable scanning takes place with a wide-to-narrow
ratio as close to 3:1 as possible.
SYMBOLOGY |
ELEMENT
RATIO |
CODE
39 |
VARIABLE
- NARROW
PLUS 2:1 TO 3:1 |
CODE
128 |
FIXED
- NARROW
PLUS 2:1 AND 3:1 AND 4:1 |
UPC/EAN |
FIXED
- NARROW
PLUS 2:1 AND 3:1 AND 4:1 |
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Carbon
Based Inks
Although
not mandatory, the use of carbon-based inks will often provide superior
scanning performance. Some hostile conditions will dictate this technique.
A number of industry standards require the use of carbon-based media.
A major exception is the retail food industry. In this case, the printing
of U.P.C. symbols on product packages with carbon inks would add excessive
cost to the process.
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Match
Environment
Rarely
has an application been found for which there is no right media solution.
Define the label requirements, including shelf life (after printing),
the number of times to be scanned and the scanning environment. Then
seek proper counsel with a reputable source who uses the latest techniques
and provides guidance on the proper marriage of various media supplies.
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Verification
A
significant majority of bar code implementation problems can be traced
back to the lack of a verification process. Whether generating media
for internal or external purposes, quality compliance (QC) will be
achieved by making verification a part of the process. Do it manually
on a random basis or do it with sophisticated equipment. Regardless
of the chosen method, DO IT!
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Resolution
For
the most effective and reliable scanning, be certain that the resolution
of either contact or noncontact devices is matched properly to the
narrowest element of any one symbol. If there are applications that
demand the scanning of a variety of narrow elements, noncontact scanners
may be required.
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Height/Quiet
Zone
For
the most effective and reliable scanning, follow the specific guidelines
for the dimensions of code height and quiet zones.
CODE |
HEIGHT |
QUIET
ZONE |
39,
128 |
>.25"
OR 15% LENGTH |
>.25"
OR 10 "X" |
UPC/EAN |
1.02"
(NOMINAL) |
.117 |
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Numbering Schemes
For
the ease and simplicity of scanning, use the shortest possible encoded
fields even if a directory file is required. Take advantage of bar
code implementation by thoroughly examining current numbering schemes
to ascertain if they can become more efficient and modernized.
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User Friendly
Low read rates are indicative of many problems, but typically the
culprits are poor quality media or inadequate operator procedures.
Media quality is addressed by proper verification methods and environmental
testing. Excellent operator performance will be achieved with training
sessions that emphasize CONFIDENCE-building along with the use of
tools like Data Identifiers or Application Identifiers. The implementation
of bar coding must be user friendly at the point of scanning.
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Support Sources
Deal
with suppliers that have extensive systems experience as well as in-depth
knowledge on bar code and other automatic identification technologies.
Be certain that both hardware and software issues can be addressed.
Work with support sources that can significantly contribute to the
planning, training and implementation processes at a systems level.
Be certain that these services will be available for an extended period
of time to accommodate the continued expansion of bar codes.
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