Bar Code Symbologies
Bar codes
have come a long way since their introduction in 1959. Today,
they can be found on nearly all products you purchase in the
store. There's probably a bar code on a product on your desk.
Your computer probably has a bar code on it somewhere.
Bar codes come in various types, sizes and formats. The most
common and recognizable type of bar code is the 'one-dimensional'
linear bar code. One-dimensional bar code symbologies include
UPC (the bar codes you see on groceries), code 128 and code
3 of 9. Two-dimensional bar codes are a relatively recent
development. These special purpose bar codes can store a great
deal of information in a small space. Two-dimensional bar
codes include PDF 417, Data Matrix and Maxicode. There are
even special three-dimensional bar codes called Bumpy Bar
Codes™. The images below show some common bar code symbologies:
How do
you know which bar code to use with your application? Certain
industries have standardized on certain symbologies (and sometimes
even the format of the entire bar code label). Certain applications
require specialized bar codes. Understanding which bar codes
to use with your application is complicated by the fact that
not all bar code symbologies can be read by all bar code scanners.
Certain symbologies require special scanners or readers. The
table below lists many of the common bar code symbologies,
their typical industry and the type of reader required:
Bar
Code
|
Industry
|
Reader/Scanner
|
Code
3 of 9 |
Mfg
|
Laser,
CCD, Wand, Imager |
UCC/EAN
128 |
Mfg,
Retail |
Laser,
CCD, Wand, Imager |
Code
128 |
Mfg,
Retail |
Laser,
CCD, Wand, Imager |
UPC
|
Retail
|
Laser,
CCD, Wand, Imager |
EAN
|
European
|
Laser,
CCD, Wand, Imager |
Interleave
2 of 5 |
Mfg,
Retail |
Laser,
CCD, Wand, Imager |
PDF
417 |
Mfg
|
Modified
Laser, CCD, Imager |
Data
Matrix 2D |
Mfg
|
Imager
|
Bumpy
Bar Code 3D |
Mfg
|
Special
Reader |
|
Bar Code Printers
Once you
have designed a bar code label you will have to decide how
to print it. Depending on your application you may need to
print bar codes on plain paper, special label stock or directly
onto box or item. When it comes to bar code printers there
many, many choices. Because of the complexity of matching
printer, ribbon, label medium, label width and application
it is impossible to provide a comprehensive description here.
A Data Net specialist can help you find the correct combination
for your needs.
As a general overview, most bar code printers are either direct
thermal printers or thermal transfer printers. Direct thermal
printers use special label stock that turns black when heated
by the print head inside the printer. Thermal transfer printers
are similar to direct thermal printers in that they include
a print head that heats up. However, thermal transfer printers
heat a ribbon to transfer the image to the label stock. Direct
thermal labels tend to fade with age and will darken if exposed
to heat or strong sunlight. Thermal transfer printers can
cost more to operate because of the extra cost of the ribbon;
however, there are many choices for ribbon composition and
color, allowing greater flexibility in label output.
Bar code printers come in a variety of shapes and sizes, including
portable printers. Data Net can help you find the right printer
for your application.
|
Bar Code Scanners
Bar code
scanners come in many different shapes, sizes and capabilities.
The simplest bar codes scanners are called 'wands'. Because
of the small size, lack of moving parts and simple construction
wands are the most cost effective bar code scanners. Other
bar code scanning technologies include laser, CCD and imaging
scanners. Laser scanners work by rapidly passing a laser beam
across the bar code to be scanned. Detectors inside the scanner
sense the light and dark bars that make up the bar code. CCD
scanners work off a similar principle but have no moving parts.
Bright light emitting diodes (LEDs) take the place of the
moving laser beam. Imaging scanners are the most complex scanners.
Imaging scanners contain a special detector that takes a picture
of the bar code to be scanned and then decodes it internally.
The following table highlights some of the difference between
these technologies:
Technology |
Strength |
Weakness |
Range |
Wand |
Low
cost |
Tethered,
limited to 1-D bar codes |
Contact |
Laser |
Scanning
range |
Cost,
most limited to 1-D bar codes, some PDF 417 |
Short
to long |
CCD |
Cost,
reliability |
Scanning
range, 1-D or PDF 417 |
Short |
Imaging
|
Reads
2-D bar codes, some have ability to capture images |
Cost |
Short |
Bar code
scanners can be separate peripherals that can be attached
to a data collection terminal or PC or they can be incorporated
directly into a data collection device. The best technology
is the one that meets your needs. Data Net can assist you
in choosing the correct device for your application.
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