How to Verify 2-D Codes
ISO 15415 verifies 2-D label-based codes
2-D barcodes typically hold dozens of characters and more information than a 1-D barcode. With a higher amount of variable data, 2-D codes are more challenging to verify and exhibit higher failure rates. Typically, 2-D codes are verified against GS1 or ISO standards such as ISO 15415 or ISO TR 29158 (AIM DPM). It is important to remember that one cannot verify with software alone. A barcode verifier built specifically for verifying 2-D codes and which uses a camera rather than a laser to capture an image of the code is necessary. As with all barcode verification, 2-D codes should be tested at the time they are printed. To successfully verify a 2-D code, a barcode verifier must accommodate specific field of view, minimum x-dimension, lighting angle, format, and software requirements.
The 45-degree angle is the most common lighting angle because it is the standard for non-DPM (paper, or regular label) verification. All camera-based verifiers must include 45-degree lighting in order to grade these regular printed codes. 45-degree lighting is stipulated in all of the ISO barcode specifications for verifying barcodes printed on a flat surface. For 2-D barcodes that are directly marked, a verifier with 30- and 90-degree lighting options in addition to 45-degree will be able to properly illuminate a variety of different background surfaces. For example, 2-D codes printed on a reflective surface work best with a 90-degree lighting angle.
Field of View
How big is the largest barcode being printed? A barcode verifier needs a field of view that is large enough to fit a 2-D barcode and still leave enough space to meet the quiet zone requirements specific to that symbol type.
How small is the smallest module (space or cell) in your code? This measurement is the minimum x-dimension. A verifier must be able to accommodate a code’s minimum x-dimension; otherwise, the camera resolution will not be able to properly capture the image needed to perform the verification.
For 2D codes on products that vary in shape and size, a verifier with the ability to adjust the camera height to the proper focus is useful. An adjustable height is also ideal for 2-D codes that are printed on a recessed portion of a part. For large barcodes or labels with multiple barcodes that need to be verified at the same time, a desktop “box” style verifier with a field of view up to six inches wide is recommended.
When judging the software component of a barcode verifier, make sure it has the functionality to grade and diagnose issues within the barcode printing process. Things to consider include whether the user interface is easy to use, generates reports, grades against ISO 15415, and shows data formatting errors.