LED backlight systems are becoming increasingly widespread and popular in machine vision applications.
Thanks to them low cost, high energy efficiency and long life, they are the ideal choice for many applications where an area needs to be illuminated evenly.
In particular, the use of LED backlights is now the preferred choice for analyze the shape and size of objects in a variety of applications.
LED backlighting is a method of lighting where the light source is behind an object, rather than in front of it as with front lighting. This type of lighting is particularly useful in the field of machine vision for analyzing size and shape of objects.
The use of LED backlights allows you to obtain high resolution images of the objects, thanks to the reduction of the effects of shadows and reflections.
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Backlighting in vision systems
In the field of industrial automation and quality control, machine vision systems play an increasingly central role in ensuring precision, reliability and traceability. A fundamental element for the correct functioning of these systems is lighting. In particular, LED backlighting represents an effective technical solution in many applications that require high-contrast images and well-defined contours. This article delves into the characteristics of LED backlighting, the advantages it offers in the industrial field and its main technical applications.
What is LED Backlighting?
The backlight, or backlight, consists of a light source placed behind the object to be inspected, with the camera positioned on the opposite side to the source. In this way, a shadow projection of the object, which allows you to highlight its profile and precisely detect its contours.
LED-based backlighting systems use a matrix of homogeneously arranged light-emitting diodes, often combined with an optical diffuser, to ensure uniform illumination across the entire area of interest. LEDs offer a long operating life, low maintenance and the ability to be electronically controlled with great precision, even in strobe mode.
Technical advantages of LED backlighting
The use of LEDs as a source for backlighting has numerous technical advantages:
- Luminous uniformity: the combination of high-quality LEDs and optimized diffusers allows for a gradient-free illumination field, essential for metrological measurement or dimensional verification applications.
- High contrast: The backlight produces binary (black/white) images with sharp edges, ideal for recognizing shapes, measuring diameters or checking presence/absence.
- Reduction of shadows and reflections: since the object is observed in silhouette, the influence of surface reflection is eliminated, particularly useful in the case of shiny or translucent materials.
- Operational flexibility: LED systems can be controlled in DC or pulsed mode, synchronizing them with the vision system for high-speed applications.
- Energy efficiency and durability: Compared to other lighting technologies, LEDs consume less energy and have a longer lifespan, reducing maintenance costs.
Design considerations
The selection and integration of an LED backlighting system requires some design considerations:
- Size of the area to be illuminated: the backlight surface must be correctly sized with respect to the object to be analyzed and the camera's field of view.
- Color of light: Typically red or white light is used, but in some applications infrared light or other wavelengths may be useful to improve contrast.
- Synchronization: In high-speed systems or environments with variable lighting, it is often necessary to synchronize the backlight with the acquisition system to ensure consistency and repeatability.
- Heat dissipation: LEDs generate heat, and proper thermal management (with heat sinks or forced ventilation) is essential to ensure stability and longevity.
Industrial applications
LED backlighting is particularly suitable for applications where the shape or edges of an object need to be accurately detected. Some examples include:
- Dimensional control: verification of diameters, thicknesses, lengths or complex geometries using optical measuring systems.
- Defect detection: identification of burrs, non-compliant holes, breaks or missing parts through profile analysis.
- Presence/absence control: checking the correct insertion of components during assembly.
- Inspection of translucent objects: analysis of plastic or glass materials which, if illuminated from the front, would show unwanted reflections.
- Packaging and pharmaceutical sector: checking the correct filling or positioning of labels and caps.
Conclusions
LED backlighting is a consolidated and extremely useful technology in the field of industrial machine vision. Thanks to its technical characteristics, it allows for precise, repeatable inspections that can be easily integrated into automation processes. Choosing the most suitable lighting system remains a crucial step in designing a vision system, and backlighting finds a wide range of applications in contexts where the profile and geometry of the object to be analyzed are crucial for quality control.
Products used in this application
DL1 Series LED Matrix Illuminators
DL5 Series High Intensity LED Matrix Illuminators
DL2 Series LED Matrix Illuminators
BL4 Series LED Backlight Illuminators
FD2 series flat dome LED illuminators
DC7 Series LED Ring Lights
DC3 Series High Intensity LED Ring Lights
DC2 Series Low Angle LED Ring Lights
More information and contacts
Systems and Sensor Integration Division: www.roder.it
Artificial Vision Division Partners: www.rodervision.com
Standard Tools Division Partners: www.innovacheck.com
More information about RODER SRL: who we are
Contact for general information: info@roder.it
The information on this website is provided for information purposes only. Although it has been prepared with the utmost care, it does not constitute a contractual offer or a binding commitment to supply. It may contain transcription, translation or typographical errors. For precise and up-to-date information, please contact our company directly.
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