Ever wondered how barcodes work? Quality spoke to John Keating, Senior Marketing Manager, Factory Automation at Cognex in Natick, MA about emerging trends in barcode technology, and how the use of barcodes has transformed manufacturing.

Quality: What are the newest trends in barcode technology?

John Keating: The most significant trends are in the transition from lasers to imagers, both in high speed, high depth of field applications, as well as in the lower end, replacing single line and raster scanners.  As imaging solutions now have the speed and resolution to replace existing technology, customers are migrating towards solid state solutions.

On the symbology side, more industries are adopting the data matrix symbology for true traceability.  Many are looking at QR Codes, but that symbology tends to be used more for consumers.

How has the use of barcodes transformed manufacturing?

It is really the datamatrix code that has transformed manufacturing. Using 2-D codes allows the manufacturer to not only trace products, and components (labels, covers for example), but also ensure that product is error-proofed, ensuring the 2-D codes match prior to packaging food. 

For industries like electronics, automotive and medical devices, barcoding  (2-D) at the component, sub assembly and assembly levels allow for true traceability, real time inventory tracking, and long term quality checking as a full assembly is traced to the component level.

How has the technology, application and use, attributed to the advancement of barcode readers?

The advances in DSP technology and speed of CMOS imagers have enabled image based barcode readers to be able to perform the high speed 1-D barcode reading for logistics applications, which previously required lasers, or expensive line scan technology.

These same technologies, DSP and CMOS have also allowed readers to be low cost enough to replace the single line laser scanners, still with high performance.

For Direct part mark, variable focus technology like liquid lens, and lower cost, high intensity LEDs have made it easier to rapidly deploy readers that can auto focus and auto tune lights.  DPM can be challenging to illuminate properly, so an intelligent tuning function can remove the guesswork to maximize read rates.

How does barcode technology relate or influence the quality sector of manufacturing?

As mentioned above, the 2-d codes are useful for quality control in process, checking the codes to ensure only the correct part, or label is used prior to moving to the next manufacturing step.  For long term quality assurance, full traceability allows manufactures to understand where defective components were used, ensuring a rapid response for the end customer when there is a quality issue.

What are the benefits and the challenges of 1-D and 2-D based codes?

2-D, particularly data matrix, has significant advantages over 1-D codes, including data redundancy (being able to read the code, even when part is missing), a smaller footprint, and the ability to uniquely mark individual parts with many characters, which is not really possible with 1-D. 1-D codes still have a large use in industry for retail uses, however, and for logistics tracking. These two are truly complimentary symbology types.

How does one determine if a laser scanner or an imaging system will best suit their decoding needs?

There is no substitute for getting an experienced sales person or applications engineer to evaluate an application.  The applications that require lasers are fewer and fewer, and typically are for very long range reading. The thing to evaluate is which type of image based reader will be most cost effective for the application.

When decoding, how does the size of the code, alignment of the reader, distance from code to camera, and contrast affect the reading?  What are the other key factors that will affect the reading?

With an imager, all of these items can be resolved with optics. There are recommended module sizes for the imager to ensure fastest speeds for 1-D or 2-D codes, and bigger is not always better.  Often times, lower resolution is beneficial for imagers that can process those smaller pixels faster. 

Algorithms are optimized for reading at extreme angles as well. The good news is that most barcode reading vendors have quick calculators to determine the field of view (image size) and optimal barcode size. The better news it that it typically only takes a short time to set up and test an image based barcode reader to get the real answer.

How have imager-based code readers changed over the years in terms of size, cost, user-friendly, life expectancy and other key factors?

There have been quantum leaps in most areas listed here. The DSPs and LED technology has allowed image based readers to get extremely small, smaller than most single line lasers. The same technologies have also seen a big benefit to the end customer in cost, where previously, a vision system or line scan would have been needed. The cost to the customer has decreased significantly while the performance has increased at an even greater rate. 

Ease of use also has seen quantum leaps. In connectivity, readers, fixed mount and handheld, are able to use industrial protocols to directly talk to PLCs on the factory network.

For ease of setup, modular illumination, liquid lens technology and advanced algorithms all work together to get a single-button setup for previously challenging applications. 

In a manufacturing environment, what information is typically housed in a barcode?

Typically, the barcode reader just passes the information on to the factory network. The readers are capable of storing and tracking a lot of information on read rate, quality metrics and others, but that is not the typical use case.

In layman’s terms, how does barcode technology work?

There are really three stages to barcode reading:

  • Finding the code – the reader looks in the image for things that “look” like barcodes.
  • Signal extraction – the reader looks at the data area in the found “candidate” and tries to
  • Decoding – the readers looks at the area within that code and decodes it based on the symbology rules (with for 1-d codes, grid information for 2-d).

For more information on Cognax ID systems, visit www.cognex.com.