Article: Solving Barcode Reading Challenges on Curved and Reflective Surfaces

August 26, 2015 - Barcode Decoding, Barcode Scanner, Direct Part Mark Readers, Embedded Machine Vision, Fixed Mount Barcode Scanners, Fixed Mount Machine Vision, Industry News, JADAK News, Machine Vision, Machine Vision, Machine Vision Services, Machine Vision Software, News

By Scott Baker, Systems Engineer

The engineering team at JADAK has the opportunity to see and solve some of the most difficult data collection challenges in the medical industry today. Our customers come to us when off-the-shelf data collection devices simply aren’t up to the challenge they’re facing and they don’t have the technology expertise and engineering resources to implement the solution in-house.

A common problem our customers face is reading barcodes on curved and reflective surfaces. This is especially prevalent in embedded applications where the requirement is to read barcodes on high contrast, non-flat surfaces in a small enclosed environment like a clinical blood analyzer. In this paper, I’ll talk specifically about the challenges of reading barcodes on challenging media and our approach to solving these issues for optimal performance.

The Challenges of Data Collection in the Clinical and Medical Setting

 There are various off-the-shelf barcode readers and suppliers to choose from. Depending on your application, many of them are adequately equipped to handle routine scanning applications.  Generally speaking, standard 1D/2D barcode readers have little difficulty reading good quality barcodes on relatively flat surfaces in a hand held application with speed and accuracy. This is sort of a ‘perfect world’ scenario, which certainly does exist in many industries and applications; retail as an example.

On the other hand, fixed mount embedded data collection in a clinical or medical environment is far more complex. Medical devices performing analysis, diagnostics, critical care functions, patient monitoring and drug dispensing have unique challenges that, more often than not, require a solution optimized for that specific use case.

Medical device form factors, especially in the clinical chemistry environment, vary greatly. Even devices that perform essentially the same function can have a seemingly endless variety of unique needs and requirements. When embedding scan engines, smart cameras or fixed mount readers, we’re generally dealing in low-light environments, near-field read ranges and very limited space to work in.

DSC_0059

JADAK fixed mount barcode scanner embedded in a clinical blood analyzer.

To complicate matters, barcodes in the clinical and medical environment come in a multitude of shapes, sizes and qualities and they’re found on surfaces that cause problems for standard barcode readers. Curved surfaces, such as pill bottles, sample vials or test tubes and highly-reflective packaging like reagent packs or pharmaceutical blister packs are just a few examples. Typically we find these situations in devices that perform sample tracking, blood analysis and automated medication dispensing, to name a few.

However, space constraints within a given device, reflective or curved read surfaces and barcode integrity are only part of the challenge. The barcode reader itself can often be the biggest hurdle to overcome. Camera-based barcode readers literally snap a picture of the target and decode the image to produce a result. As with any standard camera, these readers produce a flash.  LED’s inherent in all 2D barcode readers are designed to be the primary light source but inadvertently can cause reflections and glare. This ultimately obscures the barcode or image you’re trying to capture. Barcodes on curved and reflective surfaces greatly increase the possibility for read delays or even misreads. Therefore, the strategic placement of the reader is of foremost concern.

We see our best results when our team works closely with the customer’s design group to carefully engineer the space around the target or barcode within the device to optimize performance. Examples include:

  • The location and angle of the camera relative to the barcode surface
  • The selection of materials, surface textures, and colors of the areas surrounding the barcode and the camera
    • The strategic placement of features in the optical path of the camera and the LED’s
    • The use of strategically placed external illumination
    • The use of external illumination with a specific wavelength in combination with filters
    • Various other methods of manipulating the incoming LED illumination

Accuracy Testing

Typically, the most time intensive part of an implementation is in the testing. The vast majority of our customers demand either 99.999% or 99.9999% read accuracy. Achieving this requires an intensely methodical approach and sometimes several million scan cycles over long periods of time in order to verify such precise read accuracies. Accuracy Testing TimeframesIt’s during this time that the scan engine is put through its paces. Because each situation is unique, the engines must be specifically tuned to that particular use-case. Throughout this testing phase, our engineers continuously monitor scan engine effectiveness and will modify image capture parameters on-the-fly to ensure optimal performance.

In the end, we’re able to deliver a product that is optimized to meet a device manufacturer’s specification requirements and the end-customer’s demand for increased throughput and reduced errors. Without proper expertise and experience, tackling projects like this in-house can be a time and cost intensive endeavor.  That’s why the world’s top medical device manufacturers trust JADAK to solve their toughest medical data collection challenges.

To learn more about JADAK and our full-line of products and solutions, contact us at (315) 701-0678 or email me at scott.baker@jadaktech.com.

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