About the history
- 1948: Bernard Silver (1924–1963) and N. Joseph Woodland (1921–) get the idea for developing grocery checkouts that can automatically scan products. Woodland tries various different marking systems, including lines and circles, marks inspired by movie soundtracks, and dots and dashes based on Morse code. In October 1949, the two inventors refine their system to use bullseye patterns and apply for a patent which is granted on October 7, 1952. Their early barcode-scanning equipment uses a conventional lamp to illuminate product labels and a photomultiplier (a crude type of photoelectric cell) to read the light reflected off them. In 1951, Joe Woodland joins IBM to work on barcode technology, though the company declines to purchase his patent, which is acquired by Philco (and later RCA).
- 1960s: RCA develops a number of commercial applications until the patent expires in 1969. Work on bullseye barcodes continues, but they prove unreliable and gradually fall by the wayside.
- 1970: By now, grocery stores are beginning to explore the idea of using their own product coding and marking systems, but different stores are considering different systems, and this threatens to cause problems for large food manufacturers who sell branded goods to multiple retailers. Under the guidance of Alan Haberman (1929–2011), executive vice president of First National Stores in Boston, the stores come together to form the Uniform Code Council (UCC), later known as GS1 US, the organization that now manages barcode standards worldwide.
- 1971: Meanwhile, at IBM, engineer George J. Laurer (1925–) builds on Woodland’s ideas to develop the Universal Product Code (UPC)—the modern black-and-white striped barcode. (Read more about Laurer’s work and IBM’s contributions to barcode technology.)
- 1973: After examining a variety of different marking systems, Haberman’s grocery stores committee settles on IBM’s rectangular UPC as the standard grocery barcode. Although he didn’t invent the barcode, Haberman is widely credited with its universal adoption.
- 1974: On June 26, the world’s first grocery-store barcode scanner goes into use at Marsh’s Supermarket, Troy, Ohio in the United States. The first scanned purchase, made by Clyde Dawson, is for a 10-pack of Wrigley’s chewing gum.
- 1979: In the UK, a barcode scanner is used for the first time at Key Markets in Spalding, Lincolnshire.
- 2011: Joe Woodland and the late Bernard Silver are inducted into the National Inventors Hall of Fame in recognition of their brilliant invention.
Barcode is a method for representing data in a machine-readable visual form. Initially, barcodes represent data by varying the width and distance of parallel lines. This barcode, now commonly called linear or one-dimensional (1D), can be scanned by a special optical scanner, called a barcode reader. Then, two-dimensional (2D) variants were developed, using rectangles, points, hexagons and other geometric patterns, called matrix codes or 2D barcodes, even though they did not use such bars. 2D barcodes can be read or deconstructed using application software on mobile devices with a built-in camera, such as a smartphone.
The barcode was discovered by Norman Joseph Woodland and Bernard Silver and was patented in the US in 1951. This discovery was based on the Morse code which expanded into thin and thick rods. However, it took more than twenty years before this discovery became commercially successful. The initial use of one type of barcode in an industrial context was sponsored by the Association of American Railroads in the late 1960s. Developed by General Telephone and Electronics (GTE) and called KarTrak ACI (Automatic Car Identification), this scheme involves placing colored lines in various combinations on steel plates affixed to the sides of the railroad tracks. Two plates are used per car, one on each side, with arrangement of colored lines that encode information such as ownership, type of equipment, and identification number. The plate is read by the scanner on the side, which is located for example, at the entrance to the classification page, while the car is moving past it. This project was abandoned after around ten years because the system proved unreliable after long-term use.
Barcodes became commercially successful when they were used to automate supermarket checkout systems, a task that became almost universal. The Grocery Uniform Product Code Board had chosen, in 1973, the barcode design developed by George Laurer. Barcode Laurer, with vertical bars, is printed better than the round barcodes developed by Woodland and Silver. Its use has spread to many other tasks commonly referred to as automatic identification and data retrieval (AIDC). The first scan of the ubiquitous Universal Product Code (UPC) barcode is on a packet of Wrigley Company that chewed gum in June 1974 at the Marsh supermarket in Troy, Ohio. QR codes, specific 2D barcode types, have recently become very popular.
Other systems have made inroads in the AIDC market, but simplicity, universality and the low cost of barcodes have limited the role of these other systems, especially before technologies such as radio frequency identification (RFID) became available after 1995.
What is the barcode used for?
Various grocery products line up to show their UPC barcodes
If you run a busy shop, you need to keep track of everything you sell so you can make sure what your customers want to buy is always in stock. The simplest way to do that is to walk around the shelf looking for empty space and refill where you need to. Or, you can write down what people buy at the cashier, compile a list of all purchases, and then use it to reorder your stock. That’s great for a small shop, but what if you run a giant Wal-Mart branch with thousands of items for sale? There are many difficulties running the store smoothly. If you mark all your items with their prices, and you need to change prices before you sell items, you must repeat everything. And what about shoplifting? If you see a lot of whiskey bottles gone off the shelf, can you really be sure to sell them all? How do you know if something has been stolen?
Using barcode technology in stores can help solve all these problems. This allows you to keep records centrally on a computer system that keeps track of products, prices, and stock levels. You can change prices as often as possible, without having to put a new price tag on all your bottles and boxes. You can immediately see when the stock level of certain items starts to thin out and re-ordered. Because barcode technology is very accurate, you can be sure that any items that are lost (and apparently not sold) might have been stolen – and maybe move them to a safer part of your store or protect them with RFID tags.
Barcode-based stock systems like these have three main parts. First, there is a central computer that runs a database (recording system) that keeps a count of all the products you sell, who makes it, how much each costs, and how much you have in inventory. Second, there are barcodes printed on all products. Finally, there are one or more checkout scanners that can read barcodes.
How barcodes represent numbers from 0-9
Barcodes are a very simple idea: Give each item you want to classify its own unique number, and just type the number on the item so that the electronic scanning device can read it. We can only print the numbers themselves, but the problem with decimal numbers is that they are easily confused (eight that is printed wrong can look like three on a computer, while six is identical to nine if you reverse it – which can cause havoc in the box if you scan your cornflakes the wrong way). What we really need is a completely reliable way to print numbers so they can be read very accurately at high speeds. That’s the problem that is solved by barcodes.
Illustration showing differences in barcode strips representing numbers from 0 to 9
If you see a barcode, you might not be able to make a head or a tail: You don’t know where one number ends and the other begins. But it is real. Each digit in the product number gets the same amount of horizontal space: exactly 7 units. To represent any number from zero to nine, we can simply color these seven units with different black and white line patterns. So, number one is represented by coloring in two white lines, two black lines, two white lines and one black line, while number two is represented by two white lines, one black line, two white lines, and two final black lines.
You might notice that barcodes can be very long, and that’s because they have to represent three different types of information. The first part of the barcode tells the country where the code was issued. The next section reveals the product manufacturers. The last part of the barcode identifies the product itself. The same basic types of products (for example, four Coca-Cola bottles and six Coca-Cola cans) have a completely different barcode number.
Most products have a simple barcode called UPC (universal product code) – vertical lines with a series of numbers printed underneath (so anyone can manually enter the product number if the barcode is printed incorrectly or is damaged in the store and does not scan through the bar code reader). There are other types of barcodes that are becoming increasingly common and stores store more information. This is called a 2D (two-dimensional) barcode) and you can sometimes see it on things like self-printed stamps.
How does a barcode scanner work?
It wouldn’t be good to have barcodes if we didn’t have the technology to read them. Barcode scanners must be able to read the black and white zebra lines on products extremely quickly and add this information to a computer or checkout terminal, which can immediately identify them using a product database. That’s how they do it.
For the sake of this simple example, let’s assume that barcodes are simple on-off, binary patterns with each black line corresponding to one and each white line a zero. (We’ve seen that real barcodes are more sophisticated than this, but let’s keep things simple.)
A simple numbered diagram showing the parts of a UPC barcode scanning system and how they work.
Scan head lights LED or laser light on the bar code.
Light is reflected from behind the bar code in a light-detecting electronic component called a photoelectric cell. White areas of the bar code reflect most light; black areas reflect the least.
As the scanner moves past the barcode, the cell generates a pattern of on-off pulses that correspond to the black and white stripes. So for the code shown here (“black black black white black white black black”), the cell would be “off and on and off.”
An electronic circuit attached to the scanner converts these on-off pulses into binary digits (zeros and ones).
The binary digits are sent to a computer attached to the scanner which registers the code as 11101011.
In some scanners, there is a single photoelectric cell, and as you move the scanner head past the product (or the product past the scanner head), the cell detects each part of the black and white bar code in turn. In more sophisticated scanners, there is a whole line of photoelectric cells and the entire code is recorded at once.
In reality, scanners do not record zeros and numbers and produce binary numbers as their output: they record sequences of black and white stripes that we have shown here, but convert them directly to decimal numbers, giving a decimal number as their output.