Cobra Effect · Everyday machines
How the barcode got from the beach to the checkout
How a pattern drawn in beach sand became the code on almost everything you buy.
7 cards, read aloud in 2:41, with a test and sources.
In the late 1940s, a supermarket wanted a way to record groceries automatically at the till.
Two young graduates of the Drexel Institute in Philadelphia, Norman Joseph Woodland and Bernard Silver, took up the problem. They needed a code that a machine could read quickly and reliably.
Woodland later remembered the idea coming to him on a beach.
As a Boy Scout, he had learned Morse code, with its dots and dashes. Sitting on the sand, he pushed his fingers into it and pulled them toward him, making four lines. Wide and narrow lines, he realised, could stand for dots and dashes.
In 1952, Woodland and Silver were granted a patent for their code.
It showed codes made of straight lines, and also a round version made of rings, like a target. A round code could be read from any direction. But the lamps and electronics of the day made reading it impractical, and they sold the patent.
Lasers and cheaper electronics finally made scanning practical.
In 1972, a Kroger store in Cincinnati tested a round code developed by RCA. In 1973, the grocery industry chose a straight bar design led by George Laurer at IBM instead. Smudged rings could be misread, while smudged bars simply looked a little taller.
A scanner reads the pattern of light and dark.
A beam sweeps across the code. White spaces reflect a lot of light, and dark bars very little. A light sensor turns the flicker into a signal of long and short pulses. The widths are compared with each other, so it does not matter how fast the beam moves. A check digit catches most misreads.
In June 1974, the first product was scanned at a supermarket in Troy, Ohio.
It was a pack of Wrigley’s Juicy Fruit chewing gum. The code does not hold the price. It identifies the product, and the shop’s computer looks up the price. Woodland was awarded the US National Medal of Technology in 1992.
So when a simple idea waits decades, ask what other technology it was waiting for.
The code was invented around 1950. It took lasers, cheap electronics and an industry agreement to make it work. Now it is on almost everything you buy.
Sources
- A brief history of the bar code, Smithsonian Magazine. Woodland’s own memory of the beach, and the first scan.
- Classifying apparatus and method, Woodland and Silver, US patent, 1952. The original patent, with straight and round codes.
- The UPC, IBM. How the straight bar design was developed and chosen.
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