This article is about printing the QR Code–not the management of the data, the compatibility of the symbol with the smartphone OS, whether or not there is web accessibility where the QR Code is displayed, or any of the myriad other post-print factors that can cause the QR Code to fail.

This article discussed QR Code failure due to imaging or printing problems–not data management or web connectivity

The Ten Reasons are listed in no particular order, but module size is  probably the most frequent cause of QR Code failure.

Here they are:

  • The modules are too small or the density is too high. Reduce the amount of data or enlarge the module (and symbol) size. The modules are the dark and light squares that comprise the symbol. In digital and thermal or thermal transfer printing, each module is usually comprised of at least two pixels and sometimes more.
  • The quiet zones are violated. Yes QR Code does have quiet zones—that blank space around the symbol, and so do other 2D symbologies. The quiet zone must be at least two modules wide on all four sides of the symbol—four modules is recommended. It performs a critical function and it must be there.
  • QR Code is designed to be square, not rectangular. Square  makes it scannable from any angle.
  • Reverse printing (a light image in a dark field) is technically allowed by the ISO specification, but not universally supported by the scanning devices (smartphones). Therefore a dark image in a light field is highly recommended.
  • Colors are also allowed in the specification, but again, not all colors are supported by all scanning devices (smartphones).  What works on one smartphone may not work on another. Black on white is recommended. Yes, the ISO specification can lead you astray.

QR Code failure can occur even when the symbol is compliant to the ISO specification

  • The squareness of the QR Code is important. All modules must fall on design grid lines and must not be distorted.
  • Fixed pattern damage. While the QR Code does a remarkable job of “forgiving” printing errors and pattern damage, if the fixed pattern damaged, the symbol fails. The fixed pattern is comprised of a finder pattern and a timing pattern, basically those three square patterns in the corners of the QR Code.
  • QR Code can allow some printing distortion, but it cannot exceed module size tolerances and the modules must be uniform in both width and height.  QR Code, like all 2D or matrix symbols, is sensitive to “rogue” or “widow” modules that are very different in size than the other modules.

QR Code failure occurs when module size is non-uniform

  • When printing QR Code on a thermal or thermal transfer printer such as a Zebra® make sure the head temperature is properly adjusted so the pixels blend together to form closed modules—but not so high they encroach on the unprinted areas (clear or light reflectance modules).
  • Verify! A very least scan your QR Code with as wide a variety of smartphones as you can get your hands on—not just The press operator’s iPhone®! Use an Android® and a Windows® Mobile phone and a RIM Blackberry® and a Nokia Symbian® and…..and if you possibly can, use a real ISO-compliant verifier. Get a third party test lab to do it for you or if you’re going to use QR Code a lot, by an ISO compliant verifier.

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3db Barcode Testimonial

Our company (an advanced software company) recently worked with Barcode Test to source a barcode verifier.  Not long ago, we were awarded a contract requiring products to be marked with IUIDs in accordance with MIL-STD-130.  For that standard, marking labels must pass a verification test that evaluates many variables (contrast, size, clarity, syntax, modularity, and more).  After a thorough search, we reduced our options to a select few.

In our search for a verifier, the Axicon line caught our attention.  Barcode Test is our regional reseller for this product.   From the beginning, they were very prompt with their responses.  We ended up having a quick call with John Nachtrieb to go over our needs.  John was extremely easy to work with and provided a lot of great information.  He was very knowledgeable on the matter and was quick to offer up a demo unit (free of charge).

Upon receiving the demo verifier and testing it, a few questions arose.  John joined a call with us and answered all our questions.  Ultimately, the Axicon verifier wasn’t the best fit for us, so we shipped the demo back.  John was completely understanding.  A few weeks later, Barcode Test reached back out with another possible verifier for us to try.  While they didn’t sell that brand, they just wanted to help us find the best option that met our needs. They even offered to send us the unit that they have in-house to see if it worked to our liking. 

Barcode Test is truly a great company to work with.  Their service and willingness to help the customer are far beyond what you typically get from other companies.  They are experts in barcode quality assurance and seem willing to help in any way they can (even if that means not getting a sale and recommending another option that better fits the customer’s needs).  If anyone is in the market for barcode verification/scanning services or products, I would highly recommend giving Barcode Test a call.

Regards,

Production Manager