LEDs & Machine Vision Systems: A Perfect Match

Machine vision systems often require bright and consistent lighting, so features of interest are easier to identify and process. Barcode scanners are the most common example of machine vision, and many more affordable scanners employ red LEDs instead of lasers. Computer optical mice offer another example of LEDs usage in machine vision, as they are used to provide a surface-level light source for the miniature camera within the mouse. LEDs work extremely well considering the unique illumination demands of machine vision systems, and their employment within will likely remain one of LEDs chief applications.

LEDs emit a nearly ideal light source for machine vision systems for several reasons:

• The illuminated field requirements for machine vision systems are typically smaller and often quite expensive, so the cost of the light source is a minor concern comparatively. Conversely, the ease and frequency in which a broken light source is replaced is a major concern, when located within complex machinery. LED’s long life (50,000 hours or better on average) and efficiency are certainly beneficial in this case.
• LED elements tend to be small (some as minute as a pepper flake) and can be placed in high density over flat or shaped substrates (PCBs etc.), so that bright and homogeneous sources can direct light from tightly controlled directions onto inspected parts. This effect can often be attained with small, low-cost lenses and diffusers, helping to achieve high light densities with a high level of control. LED sources can also be shaped into several formations (spot lights for reflective illumination; ring lights for coaxial illumination; back lights for contour illumination; linear assemblies; flat, large format panels; dome sources for diffused, omni-directional illumination).
• High-powered LEDs are available that can easily produce a strobe effect (in the microsecond range and below), which make for well-lit images even with very short light pulses. When synchronized perfectly with imaging, LEDs can generate crisp and sharp "still" images, despite quickly moving parts.
• LEDs come in several different colors and wavelengths, which allow one to pick-and-chose which LED best fits their application. When a machine works to identify features of interest on a label or product, different colors may provide better results than others, separating informative bandwidth from disturbing effects of ambient light.
• LEDs typically function at comparatively low working temperatures, simplifying heat management and dissipation. This allows for the use of plastic lenses, filters, and diffusers. Waterproof units can also easily be designed, allowing use in harsh or wet environments (food, beverage, oil industries).

For more information, please contact Norlux at 630-784-7500 or visit us at www.norluxcorp.com.