Material Handling Automation (MHA) would be all but impossible without dependable and accurate data collection devices. While many of today’s material handling technologies have been around for some time, laser scanners have long been considered the cornerstone of barcode scanning. Whether the bar code labels are conventional 1D UPC (ITF-14) or standard serialized shipping container code (GS1-128), two-dimensional, or inconsistently placed on cartons, or often damaged, the capabilities of fixed-position laser scanners have clearly kept pace.

As a result, they continue to be an effective tool for scanning bar codes on cartons and other items moving on conveyor systems at speeds up to several hundred feet per minute. There is a huge array of laser scanners available that are suitable for a broad range of applications. They can accommodate:

• A range of bar code label placement on cartons and other items
• Less than perfect labels
• Conventional and two-dimensional bar codes.

Also worth noting are the compact fixed-position scanners that fit in cramped spaces making data collection possible at previously inaccessible locations.

Match Application Needs with Scanner Performance

While laser scanners will continue to play an important role, according to a 2009 article written by Cindy Zeiger, Product Manager for Accu-Sort Systems www.accusort.com, in recent years camera based scanners have become more cost competitive – especially for DC applications. In fact, Zeiger says that troubleshooting no-reads is a common use of camera images. For that reason, logistics managers who are looking to optimize their current laser scanning solutions may be wondering if switching to or adding cameras into their automated sorting system could lower operating costs even further.

For example – suppose a DC with a throughput of 50,000 packages per day has a relatively conservative no-read rate of 1.5%. Still that’s 750 packages per day that must be processes off-line. If each no-read takes a worker two minutes to handle at a cost of $20 an hour, that’s an annual cost of about $130,000.

While laser scanners have software that can decode less than perfect bar codes (smudged, torn, and otherwise damaged) and correctly fill in the gaps in the data, no-reads are bar codes that for whatever reason cannot be decoded by the software. According to Zeiger, this is where cameras have a huge advantage over lasers – the ability to capture an image of the whole label or scanning area. By viewing a snapshot, a worker can immediately see the reason for the no-read and address the issue on-line. The expense of manually processing no-reads off-line decreases while system throughput increases. In addition, the camera image data can be used for optical character recognition (OCR), further automating the process of resolving no-reads and increasing throughput.

Today, many manufactures are replacing cardboard cases with the lighter and cheaper plastic shrink wrap package. Zeiger says that cameras typically read barcodes under these types of reflective surfaces better than lasers. This is because a camera provides the full 2D image of the barcode (so it has full spatial information to work with). Therefore, if only part of the bar code is distorted or blocked by reflection, the camera may still be able to decode the data.

Finally, all other things being equal, a camera can read barcodes faster than any other type of bar code reader. This is important because conveyor speeds are increasing to speeds unheard of just a few years ago. At the same time new induction and sorting software is decreasing the gap (distance between cases), which in-turn can significantly increase the cases/minute rate of an existing systems.

Comparative Benefits

This does not necessarily mean a camera is the best choice for every application. Laser scanners have the advantage of being able to provide greater depth of focus for a given bar code density. This may be critical in applications that handle a wide range of pitch and skew with varying sizes of packages.

Zeiger points out that when compared side by side, most laser systems are simpler and easier to install than camera systems. Generally, cameras take longer to set up. And, if the application calls for image capture, then it must be integrated with an image server. On the other hand, new-generation camera systems equipped with an auto-configuration wizard, integrated decoding and illumination, can actually be installed faster and at a lower cost than lasers – the choice really depends on the application.

If you are interested in a comprehensive overview of technologies used in automated bar code systems you can download a White Paper titled “Auto ID in the Material Handling Industry” from the ACCU-SORT® Systems website (listed above) and click on downloads.

Final Thoughts

As one would expect the choice between laser and camera based scanners depends on the best fit between the needs of the operation and the scanner’s capability. In some MHA applications integration of both technologies may be required to produce the desired result. Automated scanning is a highly specialized area that offers real potential for improvement. With help from experienced MHA solution providers, logistics managers can increase the performance and efficiency of their system while lowering operating cost.

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