Innovations in Photoelectric Sensors

Photoelectric sensors have been part of modern life for decades, and they remain one of the most frequently used sensor types. The science behind this technology goes back to Albert Einstein’s theory of the “photoelectric effect” in 1905. He proposed that light energy travels through space in concentrated bundles (photons), which release electrons when they collide with metal surfaces. Therefore, light energy can be converted into electrical energy and used to create electrical current. His groundbreaking theory was proven in experiments by R. A. Millikan in 1914 and 1916, and by the late 1940s, engineers had developed photoconductive cells for use in light-sensing circuits.

A photoelectric sensor works by receiving or not receiving a directed beam of light. If the beam is uninterrupted, the photocells receive photons, but if it is interrupted, they do not. The sensor detects whenever this change occurs. While this binary “on-or-off” behavior may be simple, the practical applications for this detection method are nearly unlimited.

Outfitting factories with photoelectric sensors helps make automation possible because the sensors detect the presence or absence of physical objects (such as products being built and packaged) and send electrical signals to machines that perform specific functions at regular intervals. Photoelectric sensors are still incredibly popular, and numerous innovations in recent years have made them exceptionally reliable, compact, powerful, and cost-effective for a wide variety of applications.

Some of Banner’s recent advances in photoelectric sensors include improvements to the manufacturing process that improve detection ranges, extend capabilities, and lower costs. For example, many sensors now use injection-molded plastic lenses rather than glass ones. This improves cost competitiveness but provides the same level of optical accuracy. Plastic lenses provide some additional benefits in that they weigh less than glass ones and, in some cases, even increase the detection range.

Adding new features to a sensor once required adding new layers of internal circuit boards with more physical components. But design philosophies have evolved, and many features can now be enhanced digitally. Engineers have improved photoelectric sensors over time with updatable ASIC chips, which enable better performance, faster speeds, better ambient light immunity, and other upgrades.

Improvements in electronic engineering and design have made it possible to create sensors with stronger, brighter light (measured as excess gain), even in miniature devices like those in the Banner Q2X Series. Some sensor receivers record the angle of a reflected light beam, and this can be used for background suppression, triangulating the location of a target contrasted with the surface behind it, even if they are both the same color.

Another big innovation for automated production is IO-Link, an open communications protocol that allows users to get extra value out of their sensors. Connecting to a sensor with IO-link allows you to capture more data than you can from a legacy sensor. That means that the sensors can contribute to data analytics, providing insights to make performance improvements throughout a factory, boost productivity, provide a basis for predictive maintenance, and prevent unexpected downtime. This is a core philosophy of Banner’s Snap Signal product line.  For example, IO-Link sensors can be connected directly to IO-link ports on the DXMR90-4K IO-link Master/Controller. Then, that signal data can be transferred to a cloud-based online dashboard for real-time condition monitoring. The data can also be sent to a PLC, HMI or SCADA system.