for National Geographic News
Now used to track just about anything bought and sold in many countries, the standard bar code system was patented in the United States on October 7, 1952, but took about 20 years to go mainstream.
U.S. inventors Norman Woodland and Bernard Silver had devised a way to encode data in a bull's-eye pattern.
Their idea didn't immediately take off because the technology to read bar codes wasn't available. That's because at least two required components—lasers and digital-image sensors called charged-coupled devices, or CCDs—hadn't been invented yet. (Coincidentally, the 2009 Nobel Prize in physics was awarded to the inventors of the CCD just yesterday.)
(Also see: "DNA Bar Code Scanners to ID Species Instantly?)
Bar Code Bull's-Eye
The bar code finally made its big time debut in 1974 at an Ohio supermarket, when a pack of chewing gum became the first item to be given the now familiar swipe.
By then the bar code's bull's-eye pattern had been replaced by the black and white vertical lines still used today in the U.S. and Canada—the universal product code, or UPC.
The familiar bar code stripes had been devised to accommodate the archaic printing technology of the day, which dated back to World War I, explained George Laurer, the retired IBM engineer who invented the UPC.
Ten digits were required to fit in an area of less than 1.5 square inches (9.7 square centimeters), Laurer said.
"There was no way you could do that with a bull's-eye, because you would get smearing in the direction of the presses. You had to use something linear."
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Bar Codes: Saving Money—And Lives?
A UPC bar code's lines encode 12 digits, which contains a manufacturer identification code and a unique item code.
When an item is scanned by a bar code reader, the UPC bar code is checked against a store's database to obtain the price.
Bar codes save stores money by reducing cashier training time, enabling more efficient inventory management, and making it harder for shoplifters to swap tags, among other things. Those savings, at least in theory, are passed on to consumers.
Bar codes also help make foods safer by making it easier to trace products back to their origins—a contaminated factory, for example—said Steve Arens of GS1 US, a nonprofit organization that develops standards for UPC bar codes.
(Related blog post: "Bar Code Used to Track Field Samples in Worldwide Genetics Study.")
In the future, stores may widely adapt more sophisticated bar code systems that allow room for additional information, such as the expiration date of a product, Arens said.
Or bar codes may be replaced altogether by newer technologies, such as radio-frequency identification, or RFID.
Scanners using radio waves can read RFID tags up to several yards away and provide detailed tracking or inventory information. The technology is already in limited use, for example, to register the finish times of marathoners with RFID tags in their shoes.
But the UPC bar code is far from finished, Laurer, its inventor, said. For one thing, stores have been slow to adopt more sophisticated codes.
"The infrastructure of scanners in stores is so large that I don't think the UPC is going to be replaced for another decade," Laurer said. "It works, and it works well."
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