This article talks about all the things to consider when choosing the right barcode verifier, what to look for and how to decide on which one will fit your needs.
Several things need to be taken into consideration when choosing the right barcode verifier. You need to figure out what field of view, minimum x-dimension, lighting angle, format, and software capabilities you need for the products that you are verifying. Here is a look into each of these specific features to gather a better understanding of their importance.
Field of view
How big is the largest barcode your printing? You want to select a barcode verifier with a field of view that is large enough to fit your barcode and still leave enough space to meet the quiet zone requirements specific to that symbol type.
How small is the smallest element in your code? Meaning the size of the smallest bar or cell. That measurement is your minimum x-dimension. You want to purchase a verifier that lists an x-dimension that either matches that figure or is smaller; otherwise, the cameras in the verifier will not be able to properly capture the image needed to perform the verification.
There are several different lighting angles called out in the different ISO specs. You want a verifier with the correct lighting angle listed in the spec you are grading against. The right lighting angle is imperative in order to get proper illumination of the code to decode it.
|Lighting Angle||Ideal Barcode Type|
|45-degree||Called out in all of the ISO/IEC barcode specs as the lighting angle used for verifying barcodes printed on a flat surface, but can also be used for DPM barcodes|
|30-degree or Dome||Best for DPM barcodes printed on curved or textured parts|
|90-degree||Best for codes printed or marked on highly reflective surfaces or dot peen symbols|
The right light makes all the difference when it comes to scanning and verifying 2D barcodes. Verifiers use several different lighting angles. 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. DPM (direct part mark) verifiers have the additional lighting options of 30 and 90-degree lighting that makes illuminating symbols on the most challenging of surfaces possible. These lighting options were introduced to the verification process in the “AIM DPM” grading standard in 2006, which is now also an ISO document (ISO/IEC 29158).
Here is an example of how the same barcode looks completely different when viewed using different lighting. The image on the far left shows a symbol laser etched into metal illuminated by 45-degree lighting. The background is dark because the shiny surface reflects the incoming light away, and not up, towards the camera. The marked area is not shiny and is scattering some light, some of which does go up into the camera. On the right, the 90-degree light, which is coming straight down, is reflected back up into the camera; therefore, the shiny background appears light. However, the marked area of the code is not very reflective and therefore looks dark. Note that the image on the left is how this code would look as a non-DPM symbol, and has low contrast. The image on the right, on the other hand, appears much brighter and has higher contrast. This was one of the main drivers behind the development of the AIM DPM grading method.
When working with codes that are directly printed onto the surface of a part or onto a curved surface the addition of 30-degree lighting makes a big difference. The DPM verifier series offer 30Q, 30T, 30S and 90 in addition to 45-degree lighting options. 30Q refers to all four sides illuminated by lights at a 30-degree angle. 30T is lighting from two sides and has two options; it can be light from the top and bottom or light from the left and the right. 30S is light from a single side and as you can imagine, there are four different lighting options.
Two-sided light or 30T, is ideal for curved and/or textured surfaces. The images to the right are an example of an object with a brushed surface texture. The image on the left shows light shown from the left and the right. On the left, we see the effect of the brushed surface, which reflects some of the light from the left and right lights from “tangential” point on the brush strokes. The image on the right shows light from the top and the bottom. To get the best image the light should be oriented parallel to the brush stroke. When it is parallel, the light reflects away, as it does on a shiny flat surface. The ability to use lighting from two, and not four, sides was another driving factor behind the development of the AIM DPM grading method.
Different verifier styles work better than others on different codes depending on how they are printed and where they are on the products. If you are attempting to verify multiple products that vary in shape and size, then you need to get a verifier that has the ability to adjust the camera height to the proper focus. An adjustable height is also ideal for 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 that have a field of view up to six inches wide is recommended.
When judging the software component of a barcode verifier you will want to ask about the capabilities offered and to make sure it has the functionality you need to grade and diagnose issues within your barcode printing process. Things to consider are if the user interface is easy to use, does it generate reports, does it grade against GS1 and HIBCC specs, does it show data formatting errors?
Once you know the answer to all of these questions, you can begin shopping for a verifier.