How Image-based Barcode Readers Improve Package Sortation

Image-Based Barcode Reading
The new high-speed, area-array, image-based reader captures an entire image in a single snapshot, eliminating the need for precise encoder input or very bright, always-on illumination. Also, area scan technology is not susceptible to distortion or other undesirable image artifacts. Several recent advances in the technology now enable area scan readers to keep pace with the speeds required by package conveyors.

Also fundamental to this new generation of area scan image-based readers is new autofocus liquid lens technology. The automatic adjusting focus of the liquid lens provides the maximum depth of field for even the highest speed applications. Liquid lenses focus much more quickly and with greater range than the mechanical variety – with no moving parts. The liquid lens technology means that the size and position of a package on a conveyor need no longer compromise either throughput or read accuracy. Also, liquid lens technology simplifies installation, setup and maintenance by allowing focal-length adjustment without the need for anyone to touch the lens.

Image-based barcode reading systems begin with more information about the barcode. This advantage allows them to successfully read codes degraded by damage, orientation or distortion. To compensate for damage to the code or light reflections from the package, the analysis software can reconstruct the data of interest from any legible portion of the image.

Image-based systems can also store images for later retrieval and analysis. Archiving this information helps a distribution facility to determine the root cause for any unread barcodes and implement corrective actions, reducing the number of subsequent misreads and thereby improving process efficiency.

For example, consider a distribution facility that achieves read rates of only 98 percent. Reviewing images of unread packages might show that package handling issues caused a portion of the no-reads, and supervisors could then modify the operators’ procedures for loading packages onto the sorting conveyor to improve the read rate. If the read rate is improved to 99 percent, the reduction in the number of packages that needed to be re-read following a failure reduces the number of packages manually sorted by hundreds or even thousands per day.

Image-based systems offer setup advantages.  They display the scanner image on a monitor or industrial display in real time. As the user sets the system up, the display shows exactly what the scanner sees, ensuring that the images will be in focus and that the image will include all codes on any package that comes down the conveyor. Both initial setup and later adjustments to improve the scanner’s read rate require little specialized knowledge, minimizing setup and maintenance times.

As a result, image-based readers are easy to maintain.  And with easy review of “no-read” images, users can quickly and easily identify and rectify problems and support the systems themselves with little training. Or, they can provide most of the support themselves and call in the vendor only when absolutely necessary. The convenience of not needing to schedule, wait for and pay for vendor-supplied service can significantly reduce downtime and the accompanying costs.

Image-based readers also contain no moving parts, typically resulting in a useful life that is two to three times longer than that of laser scanners.

Power over Ethernet (PoE) technology can simplify wiring in the system. Originally invented for use in enterprise phone systems, PoE reduces cost by eliminating the need for a local DC power supply and individual 120V power drops at the scanning location.

Longer life of image-based systems makes them an attractive capital purchase

Another trend in the logistics industry is the introduction of two-dimensional (2D) codes like Data Matrix and QR. The pharmaceutical industry will be required to start using these codes for unit level serialization to combat drug counterfeiting. The amount of information 2D codes can store makes them very attractive for a wide range of other applications. Image-based scanners are required to read these codes.

Retail distribution centers require meticulous stock control, which includes careful management of purchasing, shipping and warehouse inventory. Capital equipment acquisitions that improve read rates, such as this new generation of high-speed area array image-based readers, enjoy short payback times that can be measured in months. As large retailers and Internet fulfillment centers consider capital equipment purchases to add capacity or increase throughput, raising barcode read rates by just 1 percent can significantly shorten payback schedules and increase return on investment.

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Jorge F. Schuster is director of ID sales, Americas, for Cognex Corporation. Visit www.cognex.com.