Lighting Controllers in Machine Vision: Key to Accurate Industrial Inspection

Lighting Controllers in Machine Vision: The Smart Directors Behind Industrial Inspection

In industrial machine vision, cameras and algorithms often take the spotlight. However, behind every sharp and consistent image is a carefully controlled lighting setup. One component that plays a central role in this process, yet is frequently overlooked, is the lighting controller. It is the core element that brings stability, precision, and flexibility to any vision system.

Whether the application involves a simple on-off light configuration or a high-speed inspection that relies on precise overstrobe control, the success of the system depends heavily on how effectively the illumination is managed. This becomes especially important in industries such as semiconductor manufacturing or packaging, where speed, contrast, and surface detail must be captured with high accuracy. In such environments, selecting the right lighting controller is just as critical as choosing the right camera or lens.

Understanding the Role of Lighting Controllers

Lighting controllers manage how and when the light source operates. They control brightness, pulse duration, and, in multi-light systems, the order in which lights are triggered. These factors determine how an object is illuminated at the exact moment the image is captured. The controller works in close coordination with the vision system’s camera or trigger sensors, ensuring that lighting and image acquisition are perfectly synchronized.

For applications with low speed or limited contrast requirements, continuous lighting is often sufficient. In this case, the LEDs stay on throughout the process, delivering stable illumination. However, as production speeds increase or when capturing fine detail becomes more difficult, more advanced lighting modes are required.

In trigger mode, the controller activates the light in response to an external signal, such as from a photoelectric sensor or rotary encoder. This ensures that lighting is only applied during the precise moment of inspection, saving energy and reducing unnecessary heat generation.

Overstrobe mode is designed for high-speed applications. In this mode, the light source is driven with significantly higher current for very short durations, typically measured in microseconds. This provides an intense light burst that enables sharp imaging of fast-moving objects without motion blur. To ensure safety and performance, both the lighting hardware and the controller must be designed to support these short, high-power pulses.

Using Four-Channel Controllers for Shape from Shading

Alongside timing and brightness, the direction of light also plays an essential role in surface inspection. Shape from Shading is a technique that uses directional illumination to detect surface texture. In this method, four separate lights are positioned around the object, usually at 45-degree angles. The lights are triggered one at a time, and the camera captures an image after each light is activated. Software then analyzes the shading differences in these images to reconstruct a detailed surface profile.

This technique is highly effective for detecting dents, scratches, embossing, and other subtle features on smooth or reflective surfaces like foil, plastic films, or metal parts. A four-channel lighting controller is required to activate each light independently with precise control over the timing and intensity. By combining the resulting images, the system can create a three-dimensional representation using a standard two-dimensional camera.

TMS Lite offers robust and compact four-channel controllers that are compatible with various lighting types, including bar lights, ring lights, and dome lights. These controllers support both analog and digital signals and can easily be integrated into modern vision systems.

DCM Sistemes and I-BlueDrive: Integrated Control and Flexible Sequencing

For engineers who require compactness and simplified wiring without sacrificing functionality, DCM Sistemes has developed the I-BlueDrive solution. This technology integrates the controller directly into the LED lighting unit. With I-BlueDrive, only a single power and control cable is required, reducing installation time and eliminating the need for a separate controller box.

One of the key strengths of I-BlueDrive is its support for high-precision overstrobe lighting, which is essential for fast production environments. In addition, I-BlueDrive allows multiple lights to be triggered in sequence, making it a powerful option for Shape from Shading and other multi-angle illumination techniques. Using DCM Sistemes’ DCMi configuration software, users can set pulse durations, trigger delays, current levels, and lighting order with ease.

Thanks to this flexibility, I-BlueDrive is a perfect fit for applications such as printed circuit board inspection, label verification, and high-speed surface defect detection on blister packaging or transparent films.

System Integration and Synchronization

Lighting controllers must integrate seamlessly with the rest of the automation system, including cameras, programmable logic controllers, and inspection software. Modern controllers support common industrial communication protocols such as TTL, 24V I/O, RS232, Modbus TCP, and Ethernet/IP. This allows for accurate timing, remote configuration, and reliable synchronization.

By aligning the light pulses precisely with the camera’s exposure window, engineers can prevent motion blur, enhance image contrast, and ensure repeatable results in challenging production environments.

Practical Applications in Industry

In pharmaceutical production, Shape from Shading is used to verify Braille printing on cartons. A four-channel controller activates four directional lights in succession, and the camera captures individual images for each lighting angle. These are then combined to generate a surface height profile.

In the beverage industry, overstrobe lighting is used to freeze motion in bottle inspection, delivering sharp images even at high line speeds. In electronics manufacturing, I-BlueDrive ensures that lighting is perfectly timed with the open shutter of high-speed cameras, enabling the detection of small defects during rapid part movement.

Conclusion

Lighting controllers are the brain behind the light in any machine vision system. They provide the precision and reliability needed to capture clear, consistent images that support accurate inspection and decision-making. Whether your application requires simple triggering or complex multi-directional lighting control, the right controller makes the difference between a basic setup and a high-performance solution.

With the advanced technologies from TMS Lite and DCM Sistemes, engineers can choose from a wide range of lighting control solutions tailored to their specific needs. From simple bar light control to overstrobe and multi-light sequencing, these tools help extract the most from your machine vision investment.

Need Help Choosing the Right Controller?

If you would like help selecting the best lighting controller for your application, I would be happy to provide advice, product recommendations, or integration support. Feel free to get in touch directly or leave a message.