For those of us familiar with verifying 1D barcodes like UPC and Code 128, migrating into 2D symbols like QR Code or Data Matrix seems very complicated. Why is that? With 1D barcodes it was a Data Matrix 4 Segmentfairly straightforward process, starting with the Uniform Code Council’s Universal Product Code Symbol Specification and UPC Verification Manuals (1970’s). Soon the American National Standards Institute got interested and in 1982 began studying bar code quality. Nine years later in 1990 ANSI X3-182 was published. Recognizing the importance of barcoding technology, the emergence of a global marketplace and the need for standards, the European organization CEN and the ISO soon created their own documents. In 1995 ISO/IEC published EN 1635 “Bar Code Print Quality Test Specification” and in 2000, ISO/IEC published ISO 15416. Each of these adapts and develops the specification in response to a growing and evolving set of needs and applications. This is a very organic process.

The history of the development of 2D symbol printed quality standards has been equally evolutionary, but there have been more steps in a shorter period of time. Many of the evolutionary steps have included imaging (of Data Matrix Codes) with dots—such as dot peen.  Other alternative marking technologies include laser marking, electro-chemical etch and ink jet.

Qr-code-ver-10SAE AS9132 (2002) was developed by the Society of Automotive Engineers and is an aerospace standard (AS). It specifies six print quality and technical parameters for Data Matrix symbols that are direct part marked—specifically dot peen marking. Those parameters are:

  • Quiet Zone: an unmarked perimeter of at least one element wide
  •  Symbol Contrast: the reflective difference of light and dark areas
  •  Cell Fill: akin to press or dot gain
  • Dot Center Offset: element placement error or inaccuracy
  • Dot Ovality: degree of non-roundness
  • Angle of Distortion: an early version of Grid Non Uniformity

AS9132 failed to specify a methodology—much like Traditional Verification did in the early days of 1D barcodes. Also it imposed tolerances too stringent for laser etch imaging and does not test for other attributes that could cause the symbol of fail. Because of its focus on dot peen marking, AS9132 has become a Unique Item Identifier coding standard for dot peen marking.

ISO 16022 (2006) covers Data Matrix Code only, and defines print or marking method, code structure and decode algorithms. ISO 16022 was never intended to be a verification specification.

AIM DPM (2006) addresses the special and specific needs of direct part mark (DPM) of Data Matrix Codes onto a surface in such a way as to produce a sufficient reflectance difference as to Chem_Etch_on_Metalproduce a legible symbol. This was the first attempt at producing a complete quality system for DPM imaging. It differs from all other 2D specifications by addressing the very unique challenges of obtaining the image by optimizing the camera and lighting positioning as well as varying the type of lighting to include diffuse 90 degree lighting.

ISO 15415 (2011) expands upon ISO 16022. It uses the same grading parameters and adds Modulation, Grid Non Uniformity and Fixed Pattern Damage. But it does not provide for the special imaging requirements of DPM, causing good symbols to fail. Furthermore ISO 15415 does not accommodate codes created from dots and requires a 5 scan average to produce a grade.

Dot Peen DM Code ISO 15415 assumes the symbol is always marked in black over a white background, and requires white reflectance calibration of the verifier. It allows for only  one lighting arrangement and does not accommodate the numerous marking methods, materials and non-white reflectance conditions in which Data Matrix  Codes are often used. In short, ISO 15415 is too simplistic to encompass the wide (and widening) ways in which Data Matrix Code is used.

To summarize, verifying 2D symbols is much more complicated than verifying 1D barcodes because the methods of marking and reflective differences of the  mark and its substrate are so widely varied and in some cases so minimal. As with 1D barcodes, the specifications for 2D symbols have evolved based on the  needs of the industries and applications where they are used.

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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