How do bar codes work? - a simple primer
How do bar codes work? -- a simple primer
What's black and white and read all over? Sure, its an old
joke. But before you say a zebra with a suntan or skunk in a
blender, think bar code. We've all grown accustom to seeing bar
codes at the supermarket, in our shipping and receiving
departments and on the factory floor. Some are now seeing bar
codes in a different light -- as a productivity tool for front
office applications.
At the supermarket, the bar code is telling the store inventory
system that the product you are buying has reached the checkout
stand and is being transferred out of inventory. In a sense, the
bar code is a tool for tracking the location of something,
whether it is a can of soup, or a freight car. Some are now
seeing the potential for tracking documents in the front office.
For example, each report or form a company produces can be given
a unique tracking number, which can be turned into a bar code.
This number can be a document number, an invoice number, a
purchase order number, a customer sales order number, or an
inventory control number. Virtually any number or character
string can be turned into a bar code.
Once you've bar coded your documents, all you need is an
inexpensive bar code reader. Bar code wands can be connected to
your existing PC or compatible through the computer keyboard.
Tracking your documents can then be as simple as waving the wand
across your documents bar coded tracking number. The bar code
reader converts the bars into the original numbers and
characters which created -- for example the name of a file on
your computer. Your existing software applications accept this
input as if it were typed on your keyboard. This procedure
virtually eliminates any potential error manual keyboard entry
might introduce.
Here are some of the uses for bar coding in the front
office.
* Bar code your customer files. Now you will know when they are
checked out and who has them. Just require users to log out
documents with a bar code reader placed near your file cabinets.
Use Bars & Stripes to put a bar code on the cover page of each
document, or on the document folder itself.
* Bar code your sales response literature. When the customer
mails them back, you can capture the information immediately.
* Bar code your capital equipment. Then when someone wants to
take a piece of equipment home, your receptionist or security
personnel can wave the wand and capture this important fact.
* Bar code visitor name badges. Your security can be increased
if you log visitors in and out of sensitive areas.
* Bar code information you frequently type, for example your
company's name and address, or product information during order
entry.
* Bar code your inventory. You can track your inventory as it
goes from stores to final test to QA and to shipping.
* Bar code your sensitive computer files. Anyone looking in
your computer's directory could guess that a file named
personl.doc most likely contains personal or personnel
information. But what does a file named 154001.doc contain? If
you give obtuse names to your most sensitive files and create
bar codes of the file names, then your files will be secure from
prying eyes. You can do the same with your password
Of course this is but a sampling of the myriad of uses for bar
codes.
Bar coding documents is extremely easy. Bars n Stripes
(http://www.barsnstripes.com) is a plug-in for Microsoft Word
which allows Word uses to create a bar code from any string of
numbers or characters typed into a Word document.
The History of Bar Codes
While it may seem like bar codes have been with us forever, bar
codes didn't really make an impact until the 1970's. It wasn't
until 1974 that the first bar code scanner was employed and the
first product bar coded. But the idea had been around for quite
awhile. In 1932, Wallace Flint suggested that an automated
retail checkout system might be feasible. While his concept was
deemed unworkable, Flint continued to support the idea of
automated checkout throughout his career. In fact, Flint, who
went on to become the vice-president of the association of food
chains some 40 years later, was instrumental in the development
of the UPC code.
During the 40's, 50's and 60's several code formats were
developed including a bull's-eye code, numeral codes, and
various other formats. Retail applications drove the early
technological developments of bar coding, but industrial
applications soon followed.
Initial Uses of Bar Codes
In 1948, a local food chain store owner approached Drexel
Institute of Technology in Philadelphia asking about research
into a method of automatically reading product information
during checkout. Bernard Silver, a graduate student at Drexel
Institute, along with fellow graduate student Norman Joseph
Woodland, teamed together to develop a solution. Woodland first
proposed using ultraviolet light sensitive ink. A working
prototype was built but rejected as being too unstable and
expensive.
On October 20, 1949, Woodland and Silver succeeded in building
a working prototype describing their invention as "article
classification through the medium of identifying patterns". On
October 7, 1952, they were granted a patent (US Patent
#2,612,994) for their "Classifying Apparatus and Method".
Efforts to develop a working system accelerated in the 1960's.
Bar coding was first used commercially in 1966, but to make the
system acceptable to the industry as a whole there would have to
be some sort of industry standard. By 1970, Logicon Inc. had
developed the Universal Grocery Products Identification Code
(UGPIC). The first company to produce bar code equipment for
retail trade using (using UGPIC) was the American company
Monarch Marking (1970), and for industrial use, the British
company Plessey Telecommunications (1970).
In 1972, a Kroger store in Cincinnati began using a bull's-eye
code. During that same timeframe, a committee was formed within
the grocery industry to select a standard code to be used in the
industry. IBM proposed a design, based upon the UGPIC work and
similar to today's UPC code. On April 3, 1973, the committee
selected the UPC symbol (based on the IBM proposal) as the
industry standard. The success of the system since then has
spurred on the development of other coding systems. George J.
Laurer is considered the inventor of U.P.C. or Uniform Product
Code.
In June of 1974, the first U.P.C. scanner was installed at a
Marsh's supermarket in Troy, Ohio. The first product to have a
bar code was Wrigley's Gum.
Bar Codes Demystified
There is nothing really complicated about bar codes. Think
Morse Code. When Samuel Morse invented the Morse Code back in
1835, it revolutionized long distance communications. Morse's
code described a way of encoding text suitable for transmission
via electric current over a wire. Each letter of the alphabet
was reduced to a specific pattern of dots and dashes as shown in
the following table.
Dit 1 unit of time
Dah 3 units of time
Pause between letters 3 units of time
Pause between words 7 uints of time
So the letter 'S' for example, was decoded as dit dit dit. The
letter 'O' became dah dah dah. These dits and dahs are often
represented as dots and dashes. SOS then becomes:
dit dit dit dah dah dah dit dit dit
Bar codes likewise have an alphabet of dots and dashes.
These are represented as thin bars and wide bars separated by
white space. UPC bar codes are one type of code. There are many
others. A specific code is called a symbol set or symbology. In
the UPC code, only the digits 0-9 are represented. Letters are
not allowed. Each digit is represented as a specific pattern of
thin and wide bars.
Bar codes used in retail
You're at the supermarket. You've just finished your shopping
and your items are being scanned at the checkout counter. You
ask yourself how they get all that information from that little
bar code. The short answer is they don't.
That bar code has three pieces of information in it. It does
not contain, as many believe, the name or description of the
product, its price, or any specific product detail. What it has
encoded into it is:
1. The manufacturer's U.C.C membership identification number
2. The product's identifier number
3. A calculated check digit to ensure the scanner read it
correctly
Taken together, these parts comprise the elements of a UPC bar
code. More recently, a new global standard has emerged which
incorporates the UPC into sometimes referred to as the GTIN or
Global Trade Item Number.
When the item is scanned, the bar code scanner decodes the bar
code, producing the GTIN number. The GTIN is used to do a
product lookup in the store's products database. The GTIN is
just a database record number. The database has all the
information the store personnel has entered into it about that
particular GTIN which often includes Manufacturer, product name,
description, price, color, size, etc.
The database software then supplies the necessary information
back to the point-of-sale system (the checkout register) so your
total can be calculated and your receipt printed.
Of course this is a simplistic view of it but essentially,
that's how it works.
(Note: This article was extracted from a larger article which
can be obtained from the Small Business depot. Download a PDF
version of the complete eBook (24 pages) at
http://www.barsnstripes.com/ )