การประดิษฐ์บาร์โค้ด: จากทรายชายหาดสู่สิทธิบัตร

The Invention of the Barcode: From Beach Sand to Global Standard

The barcode is one of the most consequential inventions of the twentieth century, yet its origin story spans decades of false starts, patent disputes, and near-misses before becoming the technology we know today.

The Drexel Beach Moment (1948-1949)

The barcode concept was born on a beach in Miami, Florida. Bernard Silver, a graduate student at Drexel Institute of Technology in Philadelphia, overheard a local food chain executive asking a dean to research a system for automatically reading product information at checkout.

Silver told his friend Norman Joseph Woodland about the conversation. Woodland became obsessed with the problem. In January 1949, while sitting on Miami Beach, he dragged his fingers through the sand and realized that Morse code could be extended into a visual pattern. He widened the dots and dashes into bars, creating a linear pattern that could be read optically.

The Bull's-Eye Patent (1952)

On October 7, 1952, Woodland and Silver received US Patent 2,612,994 for their "Classifying Apparatus and Method." Their design was not the linear barcode we know today but a circular bull's-eye pattern of concentric rings. They reasoned that a circular design could be read from any angle.

The patent described both the symbol and a reader using a 500-watt light and a photomultiplier tube. The technology worked in principle but was impractical with 1950s components.

The Railroad Experiment (1960s)

The first large-scale barcode deployment was by the Association of American Railroads. David Collins, working at Sylvania, developed KarTrak, a system using colored reflective stripes on the sides of railroad cars. An optical scanner trackside read the car identification as trains passed at speed.

KarTrak was installed across the US railroad network by 1970, but poor read rates in dirty conditions led to its abandonment by 1978.

The Grocery Industry Initiative (1969-1973)

The National Association of Food Chains (NAFC) formed an ad hoc committee in 1969 to investigate automated checkout. The committee established the US Supermarket Ad Hoc Committee on a Universal Product Code, which defined the requirements for a standard symbol.

Seven companies submitted symbol proposals in 1971-1973, including IBM, RCA, Singer, Litton, Pitney Bowes, and Dymo Industries. IBM's entry, designed by George Laurer with input from Woodland (who by then worked at IBM), was selected on April 3, 1973.

George Laurer and the UPC

George Laurer refined Woodland's concept into the practical Universal Product Code (UPC) symbol. Key design decisions:

• Linear bars instead of bull's-eye (easier to print on packaging)
• Binary encoding using bar and space widths
• Guard patterns for reliable scanning
• A check digit for error detection

The resulting UPC-A specification could be printed with existing packaging technology and read reliably at checkout speeds.

Legacy

Woodland and Silver's patent expired in 1969, before barcodes became commercially successful. Silver died in 1963, never seeing his invention adopted. Woodland lived to receive the National Medal of Technology in 1992 and was inducted into the National Inventors Hall of Fame in 2011. He died in 2012 at age 91.