In the late 1940s, a grocery chain from Philadelphia approached the Drexel Institute of Technology to develop custom automation that could store and read information about products during checkout. A teacher at the institute – Norman Joseph Woodland – took up the task, experimenting with various data collection methods. He eventually found one that worked, a technique that utilized Morse code to represent an assigned number for the product. Instead of the typical dots associated with Morse code, however, he extended these into lines to create a linear code.
Woodward adapted a tubelike mechanism from a movie sound system that was developed in the 1930s to help detect a movie projector’s light and convert it into sound. He adjusted it through precision automation, engineering it so that it instead converted light into numerical form. This custom automation device became the precursor for barcode scanners. Although he eventually patented the device in 1952, it wasn’t put to use until 1973, when an Ohio supermarket scanned its first item, a pack of gum.
What Exactly is a Barcode?
In essence, a barcode is simply a pattern applied to components, goods or packages that allows machines to read it. These barcodes contain information about the products, and are used for tracking purposes throughout an item’s lifecycle. To read the information from these barcodes, a special scanner that uses lenses and lights decodes the data that this pattern represents.
When used in manufacturing, automation transfers this information to a database, which helps log and track products throughout the manufacturing and distribution processes. Barcodes are now used to quickly identify products in nearly every industry, including to automate and simplify tracking of products through the supply chain
They can show:
- Where an item was produced
- Where a product was shipped
- To which retailer the merchandise was sold
- Time, data and price charged for the goods
While all this can be done manually, barcodes offer better accuracy, while also simplifying sorting and traceability. This custom automation can also be applied to reduce liability and heighten safety, as it allows defective products that reach store shelves to be quickly identified, accelerating safety recalls while also making data regarding quality control available throughout the supply chain.
How Barcode Readers Work
There isn’t just one type of barcode reader, so understanding how barcodes work differs depending on the method of automation. Engineering of barcode readers also varies based on the marking or printing methods involved in making these barcodes. To understand how barcodes work in both retail and manufacturing, automation between barcodes and readers must be appropriately synchronized.
Types of Barcodes
There are dozens of barcode formats, with thirty major ones, though they can be separated into two basic categories. Those made up of a row of lines is referred to as 1D – or one-dimensional – barcodes. Meanwhile, 2D – or two-dimensional – barcodes are made up of dots and squares. 2D codes invariably contain more data than 1D codes, which store data only horizontally, as their vertical patterns also hold information.
Using numeric or alphanumeric data, 1D barcodes were the first type utilized globally. These linear codes are usually read from left to right, storing information horizontally, with each character representing a different aspect of the merchandise in a database that defines each character’s meaning. The width of each space and bar relates directly to specific characters, with quiet zones – those white spaces to the right and left of the barcode – helping the reader locate the barcode. These zones generally occur at least seven times through the narrowest part of the barcode.
Bars in the code work according to the ratio between their width and that of the narrowest bar, with common ratios being 2:1. 2.5:1 and 3:1. These ratios describe the width of quiet zones compared to that of the black bars, basing these ratios from the starting point of the narrowest of the black bars in the code. Some barcodes include what’s called a guard pattern, which shows where the barcode begins and ends.
Commonly used 1D barcodes include:
- Codabar barcodes are used when serial numbers are required, including for blood banks and delivery services as well as for membership cards.
- Code 128 barcodes can encode 128 characters in numeric or alphanumeric formats, and they’re used for various medical applications, shipping labels and ID cards as well as by the United States Postal Service (USPS).
- Code 39 barcodes are used widely for military purposes, badges, industrial applications and inventory.
- EAN (European Article Number) barcodes are standard in the European Union, used to identify specific retail goods, along with how they’re packaged and their manufacturer.
- GS1 barcodes are used universally in the logistics industry to identify goods, pallets and places they’ve traveled along the supply chain.
- Interleaved barcodes use only a numeric format, employed for encoding number pairs into a high-density self-checking format.
- POSTNET barcodes are used by the USPS for direct mailing.
- UPC (Universal Product Code) barcodes are used for consumer and retail products.
Most 1D barcodes also include a check digit that’s used to verify that the code isn’t missing information or damaged, and that it’s complete.
With capabilities for coding information vertically as well as horizontally, 2D barcodes store far more data. Single 2D barcodes can contain 2335 alphanumeric characters or 3116 numeric characters, in comparison to 39 characters for the 1D barcode Code 39. Additionally, 2D barcodes have custom automation capabilities that allow them to correct errors and help eliminate misreading.
2D barcodes also have quiet zones similar to 1D codes, though these surround the entire code. These barcodes also feature finder and clocking patterns that identify where the code begins and where it ends. Finder patterns are L-shaped, located on the outside edge along two sides of the barcode, which ensures they’re properly oriented when being read. Clocking patterns are opposite of finder patterns, with alternating black and white cells in a series defining the size of single cells and the barcode being decoded.
Commonly used 2D barcodes include:
- Aztec barcodes are used by vehicle rental companies and ticket agencies.
- Data Matrix barcodes are used in the print media, defense and aerospace industries, as well as by the USPS.
- MaxiCode is used for logistics, with its code based on dots.
- QR (Quick Response) barcodes are used for commercial marketing applications and in the automotive industry.
2D barcodes tend also to have more redundancies, with Data Matrix codes typically having data encoded thrice, which considerably reduces the chance of an incorrect reading.
Types of Barcode Readers
Barcode readers – also known as barcode scanners – are devices with sensors, lights and lenses that decode the data within a barcode. The first 1D barcode scanners used lasers and oscillating mirrors (or prisms that rotated), with the laser beam scanning back and forth along the barcode. A photodiode measured light reflected from the barcode, creating an analog signal that was then converted into a digital signal.
All coding takes place by collecting information from a central database that includes manufacturing data, with the barcode then applied to a label on, or directly to, the object. These typically utilize thermal or inkjet printing methods, with codes placed via direct part marking (DPM). These include custom automation techniques such as chemical etching, dot peen or laser marking.
There are five basic types of barcode readers:
- Slot scanners: A stationary barcode reader, they require users to pull items by hand through a slot in the device. These readers are typically used for reading cards that require swiping, including ID cards.
- Pen wands: As the simplest and least expensive barcode reader, pen wands have no moving parts, so tend to last longer than other readers. Though durable, these readers require direct contact with the code, must be held at a certain angle to read data and read data only when it passes over the barcode at a certain speed.
- Laser scanners: Used either as stationary or handheld devices, they don’t need to be close to the barcodes they read, with typical models able to read from 24 inches (about 61 cm) away and longer-range models reading as far as 30 feet (about 9.1 m) away. Using lenses and mirrors, they read barcodes regardless of their orientation and in a single second can process up to 500 scans.
- Image scanners: Also referred to as camera readers, these readers feature small cameras that capture the barcode’s image. Featuring digital imaging processors, they can read barcodes from a distance of about 9 inches (about 23 cm).
- CCD (charge-couple device) scanners: Often used in retail, these readers use a gun-like interface. With better range than pen wands, these devices still need to be close to the items they’re reading, though they can only read barcodes as wide as their face.
EAM Custom Automation: Engineering Logistics Labelling
EAM Inc. designs, manufactures and installs a variety of packaging and logistical equipment and accessories. This includes the company’s EAM Cooper Feeder, which encodes barcodes and supports barcode readers.
Features of the EAM Cooper Feeder include:
- Adjusts easily to product widths
- Auxiliary handshaking and triggers available for barcode readers
- High-speed feeding system for cards
- Intuitive set-up through OIT (Operator Interface Terminal) touch screen for batches, counts, spacing and speeds
- Labor Ready! integrated encoder with trigger outputs
For more information on our Cooper Feeder or other custom automation products, contact us today.