Why do different barcode scanners behave differently? Even some scanners of the same brand and model behave differently. Why is this?

Barcode scanners, like other devices, are manufactured to a specification, and every specification has a tolerance or margin of acceptable performance error. This is why even otherwise “identical” scanners of the same make and model will differ, usually slightly. These subtle differences can be magnified over time, so an older version of a barcode scanner of a particular brand/model can behave significantly differently than a new version of the same barcode scanner make/model.

Within a barcode scanner manufacturer’s family of products, different models will have very different specifications. Some are engineered to scan barcodes at long range, such as shelf tags in a warehouse which are often scanned from the forklift. Some are engineered to scan extremely high density barcodes with extremely small X dimensions—often as small as 3mil. Some barcode scanners are designed to scan low density barcodes with large X dimensions at relatively close range.

Then there is the issue of light sources. The earliest barcode scanners were serial interface wands. This is such old technology it is largely and thankfully gone, but they were very prone to operator-induced performance variations.  Today one could encounter laser scanners, LED (CCD) scanners and camera-based imager-scanners; very different technology and performance between them.

Laser scanners capture barcode data by measuring the laser light reflected back from a barcode.  The reflected light receptor is a diode that converts the reflectance impulses into a digital signal. Because laser scanners have moving parts, their performance can vary according to how they are handled by the user, and how they might have been abused or damaged in use. Moving parts wear, and older laser scanners perform differently than newer laser scanners.

Unlike a laser scanner with a single laser light source, an LED or CCD scanners capture barcode data with a long row of many LED’s that illuminate the barcode.  It is important that they all produce   exactly the same light intensity and color, but this can vary from LED to LED and scanner to scanner.

Camera-imager scanners are yet different still. They are somewhat like CCD scanners except that camera based scanners have a 2D array of tiny lights and take a digital picture of the barcode or 2D symbol, which is then decoded and analyzed with software. Different makes/models use different qualities and focal length lenses–they are cameras after all. Different makes/models use receptors of different resolutions; some are better suited to low density barcodes with larger X dimensions, others to high density barcodes with smaller X dimensions.  Like with any camera, lenses that are dirty or scratched degrade the image quality and scanner performance.

Knowing this helps to understand why different barcode scanners behave differently and why it is a very bad idea to use a scanner as a barcode test device.  The performance of any particular scanner is a meaningless predictor of how that barcode will perform on another scanner—even one of the same make and model.

If you need to get a barcode tested, contact Barcode-Test for a quick and comprehensive test including the verification report and a plain-English explanation.