LOGISTICS is a dynamic and fast-paced sector where multiple systems operate simultaneously at high speeds to keep items moving smoothly through each stage. To maintain efficiency, these systems must be both fast and reliable, with minimal disruption. Modern logistics environments depend on consistency and flexibility, and scan tunnels have emerged as effective machine vision solutions, offering fully automated inspection for a wide range of items and enabling accurate, high-speed sorting.
HOW DOES A SCAN TUNNEL WORK?
Scan tunnels are widely used in high-speed environments where efficiency and accuracy are critical. They enable dynamic logistics operations by delivering reliable barcode and label reading. Mounted within a fixed frame above a conveyor in a tunnel-like configuration, scan tunnels inspect items as they pass through. The system integrates machine vision cameras, advanced lighting, and, in some cases, additional sensors into a robust structure to create an optimal imaging setup.
As objects move through the tunnel, high-intensity lighting briefly illuminates each item while cameras capture high-resolution images. These images are then processed by connected software to detect defects, dents, or missing components with precision.
Why is Lighting Importan in Scan Tunnel Systems?
Objects travel along conveyors at exceptionally high speeds, requiring vision systems that can keep pace while still capturing high-quality images. At these speeds, it becomes increasingly challenging for machine vision cameras to acquire clear images without blur.
Relying on cameras alone often leads to missed defects, reduced inspection efficiency, and images that are difficult to interpret. Variations in ambient light can further reduce reliability, making it harder to consistently detect barcodes, labels, or surface defects.
To overcome these challenges, controlled, high-performance illumination is essential. Powerful lighting enables cameras to operate at extremely short shutter speeds, effectively freezing motion and significantly reducing blur in high-speed applications. Just as importantly, it provides consistent, uniform illumination, ensuring reliable image capture and repeatable inspection results regardless of environmental conditions.
Where to Position Lighting on Scan Tunnels
LIGHTING is most effective when positioned at the top and sides of the scan tunnel frame, as shown in the diagram, ensuring consistent illumination as items pass through and are captured from all angles. This configuration ensures that all surfaces of the object are properly illuminated, enabling more reliable and high-quality imaging results.
LIGHTING CHALLENGES FOR SCAN TUNNELS
Challenge 1: Eliminating Motion Blur in High-speed Imaging
The manufacturing and logistics industry operates at high speed, handling large volumes of parcels every day. In scan tunnel applications, lighting must be precisely synchronised with camera exposure to ensure sufficient light is delivered at the exact moment of capture, enabling sharp and accurate images.
Challenge 2: Achieving Uniform Illumination Across Moving Objects
Scan tunnels require consistent, high-intensity illumination to ensure objects are evenly lit as they pass through the system. Without stable and uniform lighting, variations in brightness can reduce image quality and impact inspection reliability.
Challenge 3: Maintaining High Performance Within Compact Conveyor Environments
High-speed conveyor systems demand lighting solutions that deliver strong output from a compact footprint. Often, many fixtures are used along the inspection axis in order to provide full coverage, taking up space and compromising inspection performance.
Challenge 4: Difficulty Illuminating Large Field of View (FoV)
During some scan tunnel inspections, systems often suffer from hot spots in the middle. This can cause issues in pick and place and large FoV applications. Capturing uniform lighting is essential for accurate inspection and faster production.
High-Performance Lighting Solutions for Scan Tunnels
Solution 1:
Fast Illumination Rise Time to Prevent Motion Blur
Using high-intensity lighting with an ultra-fast rise time is key to eliminating motion blur in high-speed applications. TPL Vision’s High Power Strobe Bar (HPS) Light features a rise time of less than 800 ns, enabling machine vision cameras to operate at extremely short shutter speeds while maintaining image clarity. This allows vision systems to achieve minimal exposure times without sacrificing depth of field, resulting in sharper, more detailed images even in demanding environments.
Solution 2:
High-Intensity Lighting for Perfect Homogeneity
With high-intensity illumination and precise positioning, users can achieve exceptional homogeneity across the field of view. The HPS Bar can deliver up to 2.5 million lux at a 200 mm working distance, providing the intensity required for demanding machine vision applications. By configuring three bar lights around the scan tunnel frame, highly uniform lighting can be achieved for scanned objects.
Solution 3:
Optimising Space for Complex System Setups
High-intensity lighting reduces the number of light sources needed within the scan tunnel. The HPS Bar provides sufficient illumination that typically only one unit per side is required, freeing up valuable space for cameras, optics, and other vision system components. This streamlined setup also allows for a wider field of view, making it easier to accommodate larger objects without compromising inspection quality.
Solution 4:
Varying Illumination Intensity to Eliminate Hotspots
By adjusting the beam angle, it is possible to reduce the hotspot commonly seen in scan tunnel applications. Users can simply attach TPL Vision’s Angle Changers to the front of the HPS Bar to create a curved intensity profile. Through reducing the intensity of the illumination in the centre of the HPS Bar light with a wider Angle Changer, this will achieve a much more uniform image while retaining high brightness.
Scan Tunnels are essential in modern logisitics...
to ensure fast and accurate automated inspection in high-speed environments. Lighting is crucial in applications to prevent motion blur, inconsistent illumination, space constraints, and uneven light distribution. High-performance lighting solutions like TPL Vision’s HPS Bar, combined with optical accessories such as Angle Changers, help address these issues by delivering fast, uniform, and adaptable illumination. This ensures clearer imaging, improved inspection reliability, and more efficient system design, supporting the demands of high-throughput logistics operations.
