Bar Code

Barcodes are everywhere, we use them every day, from so common visit to the supermarket to serious aspects of our work, they are part of our lives.

But how did barcodes come about? Who invented them? Where was a barcode first used? And in what context? Have these questions ever crossed your mind while waiting in line at the supermarket? I do, and I tried to answer them all. For those who are curious, we invite you to learn everything about barcodes with us.

What is a barcode and how does it work?

A barcode is a way of representing characters (numbers and/or letters) in a printed form, which can be read and decoded by specialized equipment.

There are a variety of "types" of barcodes called symbologies, as well as a range of different technologies for reading them. Because a barcode contains only encoded characters, the barcode scanner must simply decode the encoded characters and make them available to the computer for processing.

The structure of a barcode varies from symbology to symbology.

Start/Stop characters are special codes that define each start and end of a barcode.

The Check character (the control character or the checksum) is a character that appears in the barcode and is generated based on the characters encoded in the barcode. In some symbologies the control character is optional, while in others, it is always present. In figure 1.3.1. coded 123456789012 in EAN-13 symbology. The control character is 8 and is the last character in the barcode.

The quiet zone consists of the white spaces to the left and right of the barcode and helps decoders locate the barcode in the plane more easily.

Bearer Bars are horizontal bars printed at the top and bottom of some barcodes.

Stop bars are often unusable because of the Start/Stop characters and are only used in isolation and in cases of symbologies that do not support Start/Stop characters.

History of barcodes

In 1932 an ambitious project was started by a small group of students from Harvard University, led by Wallace Flint. Landmarks from product catalogs were attached to the products and were centralized in a database. Bar codes, in their modern form, began to appear in 1948. Bernard Silver, a graduate of the "Drexel Institute of Technology" in Philadelphia, received a request to develop an automatic product identification system. Silver told his friend Norman Joseph Woodland about the order he received. Woodland was 27 years old and a professor at the same institute. The problem fascinated Woodland and he started working on this project.

Woodland's first idea was to use a type of ink that would become bright under the action of ultraviolet radiation. Woodland and Silver created a device that worked, but the system had problems with ink instability, and printing the patterns was very expensive. Woodland was convinced that their idea was good, so he quit teaching and moved to his grandfather's apartment in Florida to have more time to work.

On October 20,th 1949, Woodland and Silver published a paper entitled "Classifying Apparatus and Method". The inventors described their invention as "the art of classifying products based on patterns”.

Most of the barcodes that Woodland and Silver described were made up of a series of circular spirals. While the two described them as symbols, the basic bar code symbology was very similar to today's one-dimensional bar codes.

The symbology was made of a pattern consisting of 4 white lines on a dark background. The first line was the control line, and the other 3 lines were fixed at variable distances from the first (control) line. The information was coded by the presence or absence of one or more lines. Thus, 7 different product classifications could be achieved. By adding more lines, more product classifications were possible. With a number of 10 lines, 1023 different classifications were possible.

The barcode model developed by Woodland and Silver on October 7, 1952 began to be used as a general product identification model. In 1962 Silver died at the age of 38, before he could see the use of barcodes in commerce. In 1992 Woodland was awarded the "National Medal of Technology" by President Bush.

Bar codes began to be used in commerce only after 1966. The "National Association of Food Chains" commissioned an electronic equipment manufacturer to create equipment that could read bar codes for a evidence and a much faster inventory of products. In 1967 the first barcode scanner was installed at a store in Cincinnati. The barcodes were represented according to the model made by Woodland and Silver. These barcodes were not printed directly on the packaging, but on labels that store employees stuck on the products. The system was recognized as a model of automation and identification of products and was adopted by all manufacturers and distributors of products.

In 1969, the same association asked Logicon to develop a system for the barcode industry. The results were the creation of the Universal Grocery Products Identification Code (UGPIC) standard in the summer of 1970. Three years later, the UPC symbology was adopted for product identification in the US. It was implemented by IBM and developed by George Laurer, who continued Woodland and Silver's idea. Woodland was an IBM employee at the time.

The first attempt to apply automatic identification on an industrial scale was started in the late 1950s by the American Association of Carriers. In 1967 a barcode format was adopted. Car tagging and installation of readers began on October 10, 1967. It took 7 years until 95% of the cars were tagged. For various reasons the system could not work and was finally abandoned in 1970. In 1981 the US Department of Defense adopted the Code39 barcode format in the military industry.

How to decode a barcode?

When a barcode is scanned, the optical elements in the scanner convert the black and white bars in the barcode into an analog (ie non-digital) electrical signal that varies depending on the light/dark parts of the barcode. The scanner can "see" the barcode as an electrical signal with a high or low compatibility pattern.

So far the barcode has been represented in an electrical form, the next step is to convert it from an analog signal to a digital signal, a digital signal that can be read by a computer. The decoder analyzes and decodes the signal according to predefined rules. The decoding rules (algorithms) are defined by the symbologies of the barcodes to be decoded.

Why do some barcodes have numbers and letters?

The practice of printing characters below the bars of the barcode are visual information only. They do not influence the decoding of the barcode. If for various reasons the barcode cannot be decoded (encoding was wrong, print quality is poor), then as a backup measure are the characters printed under the barcode bars. Some symbologies have rules that require characters to be printed below the barcode. Although these characters printed below the bars of the barcode do not help or hinder the reading of the barcode by the scanner it is a good practice to print them to enable human reading of the barcode.

You certainly didn't know that:

Train and plane tickets have their own barcode called Aztec, which is probably the coolest name for a barcode symbol - Aztec is a two-dimensional code.
The Aztec Code was invented in 1995 by Andrew Longacre and Robert Hussey. The two worked at medical device manufacturer Welch Allyn. As well as being used in healthcare, Aztec is now popular in the transport sector and can be found on train tickets.
It has also been chosen by the airline industry as the standard barcode for electronic boarding passes. So if a boarding pass was sent to your phone, it's likely to contain an Aztec code. Many rail companies across Europe – including the UK, France and Switzerland – use it similarly.
Unsurprisingly, its name derives from the central part of the code, which is said to bear a resemblance to an Aztec pyramid.

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Bar Code

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