Patent 2,612,994 PDF - Original Barcode Invention
US Patent 2,612,994, filed by Norman Joseph Woodland and Bernard Silver on October 20, 1949, and granted on October 7, 1952, represents the first barcode system ever patented. This foundational document describes a “Classifying Apparatus and Method” using concentric circular patterns to encode information—a design radically different from today’s linear barcodes, but embodying the same core principle of machine-readable data. The patent drawings show a bull’s-eye pattern read by photomultiplier tubes, establishing the technical framework that would eventually evolve into modern UPC and EAN standards.
Full Text of Original Barcode Patent
Patent 2,612,994 opens with a straightforward problem statement: the need for automatic classification and sorting of items without human intervention. Woodland and Silver describe their invention as “apparatus for classifying objects and articles of various kinds according to identifying indicia placed thereon.” The specification runs 14 pages, detailing a system where coded markings would be applied to merchandise, then scanned by a photoelectric reader connected to classification circuitry.
The inventors explicitly cite railroad car identification as their primary application—they envisioned solving the problem of tracking freight cars automatically as they moved through rail yards. The document states: “The present invention contemplates the provision of coded indicia which may be rapidly and accurately read by relatively simple apparatus.” This sentence captures the essential barcode promise: speed, accuracy, and mechanical simplicity.
What makes this patent historically significant isn’t just priority—it’s the completeness of vision. Woodland and Silver didn’t merely propose marking objects with lines. They detailed the complete system: marking methodology, optical scanning hardware, signal amplification circuits, and decoding logic. The patent describes using ultraviolet-fluorescent ink to improve contrast, a technique that predates modern barcode printing by decades.
Technical Drawings and Diagrams
The patent includes seven figures, with Figure 1 showing the iconic concentric circle design. Unlike modern linear barcodes, this bull’s-eye pattern could be scanned from any angle—a significant advantage Woodland recognized from his background in Morse code. The circles varied in width to encode different characters, with ten distinct circle combinations representing digits 0-9.
Figure 4 depicts the scanning apparatus: a 500-watt incandescent lamp illuminating the code, with reflected light captured by a photomultiplier tube. The optical path included filters and a lens system focusing light onto the detector. This wasn’t theoretical speculation—Woodland built a working prototype on his father’s property in Florida, using a movie soundtrack optical reader and parts salvaged from other equipment.
The circuit diagrams in Figures 5-7 show remarkable sophistication for 1949. The system used vacuum tube amplifiers (transistors weren’t commercially available yet), discriminator circuits to distinguish wide bars from narrow ones, and relay logic to decode the signal patterns. According to IEEE’s historical documentation, Woodland’s prototype successfully demonstrated automated reading, though the technology wouldn’t become commercially viable for another two decades.
Classification Apparatus Methodology
The patent describes a two-stage process: encoding and decoding. For encoding, the inventors specified that “the classification markings consist of a plurality of concentric circles of different widths and spacings.” Each coded element represented either data or control information. The outermost circle served as a timing reference, while inner circles encoded the actual classification data.
Decoding methodology relied on measuring relative widths as the scanner moved radially across the pattern. The system generated electrical pulses proportional to bar widths, then compared these pulses against threshold values to determine whether each element was “wide” or “narrow.” This binary width modulation—the foundation of most modern barcode symbologies—appears here fully formed in 1949.
The patent claims an accuracy mechanism that remains relevant today: redundancy through multiple readings. By scanning across different radii of the circular pattern, the system could verify data integrity through comparison. If readings disagreed, the system would signal an error rather than pass incorrect data downstream. This error detection philosophy underpins every modern barcode standard from Code 39 to QR codes.
Patent Claims and Specifications
The patent includes 13 numbered claims, progressing from broad to specific. Claim 1 establishes the fundamental concept: “In combination with an article, indicia affixed to said article for identifying and classifying said article, said indicia comprising a plurality of concentrically arranged elements, the pattern of said elements being unique to said article.” This sweeping claim covers any concentric pattern encoding system.
Subsequent claims narrow the scope, specifying the optical reading apparatus, the amplification circuitry, and the decoding logic. Claim 7 describes “a source of radiant energy directed at said indicia, a photoelectric cell positioned to receive radiant energy reflected from said indicia.” Claim 11 details “means responsive to the output of said photoelectric means for comparing the relative widths of said elements.”
The specifications section provides dimensional guidance: element widths ranging from 0.125 to 0.5 inches, with minimum spacing between elements of 0.05 inches. These numbers reflect practical limitations of 1949 optical systems—modern barcodes achieve far higher densities. The patent also specifies reading speeds “up to 100 articles per minute,” ambitious for vacuum tube electronics but trivial by today’s standards.
Woodland and Silver assigned their patent to Philco Corporation, receiving $15,000 for rights that would eventually enable a trillion-dollar global industry. The patent expired in 1969, just as barcode technology began commercial deployment, allowing the subsequent UPC standard to develop without licensing constraints.
Historical Document from October 1952
When Patent 2,612,994 issued on October 7, 1952, it arrived into a world unprepared to implement it. The technology gap was brutal: Woodland’s system needed computing power that wouldn’t exist affordably until the 1970s. The patent sat largely dormant for fifteen years while laser technology, integrated circuits, and digital computing matured enough to make automated scanning economically viable.
The October 1952 patent office examiner’s approval stamped this document as officially “useful, novel, and non-obvious”—the three requirements for US patents. Reading it today, the novelty and non-obviousness are obvious. The usefulness would take two decades to prove. RCA attempted to commercialize Woodland’s bull’s-eye design in the early 1970s for supermarket scanning, but the pattern’s complexity and printing requirements led the industry to adopt the simpler linear UPC format instead.
This patent represents a peculiar historical artifact: a technically correct solution superseded by simpler implementations. Woodland’s concentric circles solved the omnidirectional scanning problem elegantly, but required circular printing precision that 1970s label manufacturers couldn’t deliver consistently. The linear barcode standards that eventually dominated were technologically inferior in some ways—requiring aligned scanning—but vastly easier to print and verify.
The document itself, preserved in USPTO archives and available through Google Patents, uses language and drafting conventions of mid-century patent practice. The formal “whereas” clauses, the elaborate dependent claim structures, and the absence of computer terminology (because general-purpose computers barely existed) mark it as distinctly pre-digital. Yet the core concepts—machine-readable data, error detection, automated classification—remain foundational to every barcode system deployed today.
Frequently Asked Questions
Q: Where can I access the complete Patent 2,612,994 PDF document?
The full patent document is available through the USPTO patent database and Google Patents. BarCode 1 maintains a local copy of the original patent for historical reference. The PDF contains all 14 pages including the complete specification, claims, and technical drawings. Most patent databases provide free access to expired patents, and 2,612,994 entered the public domain when it expired in 1969, making it freely available without licensing restrictions.
Q: Why did Woodland and Silver use concentric circles instead of parallel lines?
Woodland specifically designed the bull’s-eye pattern to solve the alignment problem—concentric circles can be scanned from any angle, while parallel lines require precise scanner orientation. He drew inspiration from Morse code, which he’d learned as a Boy Scout, recognizing that varying element widths could encode information. The circular design eliminated the need for careful positioning during scanning, a crucial advantage given the mechanical limitations of 1950s automation. Ironically, this sophisticated solution proved too difficult to print reliably, and the industry eventually adopted simpler linear codes with fixed scanning orientation.
Q: Did Woodland and Silver profit from inventing the barcode?
Not substantially. They sold their patent to Philco Corporation for $15,000 in the early 1950s—roughly $175,000 in today’s dollars, but a trivial sum compared to the technology’s eventual economic impact. Woodland later worked for IBM, contributing to the development of UPC standards in the 1970s, but as a salaried employee rather than as a patent holder collecting royalties. By the time barcodes became commercially successful, Patent 2,612,994 had expired, allowing the industry to develop without paying licensing fees. Both inventors received recognition late in life, with Woodland inducted into the National Inventors Hall of Fame in 2011.