Photoelectric sensors and their uses

The market for photoelectric sensors is expected to grow to more than US$2 billion by 2025, driven in part by the rise of the Internet of Things (IoT). They are used in many different applications, often in manufacturing and packaging, and have some significant advantages over other sensors. In this article we’ll explain how they work, and compare the different types, then list seven typical uses.

How photoelectric sensors work

In basic terms, the sensor detects visible or infrared light emitted from a transmitter. By sensing how much light is received, and hence how much has been reflected or blocked, it can determine useful information, such as the presence or absence of an object – for example, on a production line.

Compared to other types of sensors, photoelectric sensors can detect objects a relatively long distance away, up to several metres, and provide fast, accurate results. They also do not require any contact with objects, improving reliability, and can detect almost any kind of item, whatever it is made from.

There are three main types of photoelectric sensors in common use:

A light beam is sent towards the object of interest, and the sensor detects reflected light.

Light is sent towards a reflector, and the sensor detects the reflected light – an object being detected may block the transmitted or reflected light.

Light is sent to a separate receiver, and the object of interest blocks the transmitted beam.

Within these main types, there are various different kinds of sensor with specialized uses. For example, some sensors can suppress the background, making it easier to detect an object close to reflective surroundings.

Applications for photoelectric sensors

There are too many applications to list in one article, but here are seven good examples:

Checking objects on production lines or conveyors: photoelectric sensors can detect items’ sizes to spot any errors, or simply spot their absence, as well as picking up problems like misaligned caps on bottles. They are widely used in the food and pharmaceutical industries, and in packaging plants.

Counting small objects: in some production environments, small items will fall from a vibrating conveyor belt into a packaging system or bag – and a photoelectric sensor can count them.

Detecting colours: by scanning independently in red, green and blue light, with applications in multiple processes in the printing and packaging sectors.

Monitoring bigger areas for objects with light grids: instead of using multiple sensors, a ‘light grid’ uses parallel beams of light to cover a two-dimensional area.

Measuring distance: with multiple sensors, a triangulation process compares reflected laser beams, and can be used to accurately determine position and distance, for example to check the location of manufacturing systems, or in automated transport applications.

Logistics and materials handling: automated warehouses with robotic pickers or trucks rely on position and object sensing to operate efficiently and safely.

Automatic doors: in buildings or public transport, photoelectric sensors detect when someone is standing by a door.

Reliable sensing

There are many, many more applications for photoelectric sensors, but it can be seen that a lot of them are in industrial or manufacturing settings – where the environment can be harsh, and components must be rugged and reliable.

To meet these demands, Bulgin's slim line photoelectric sensor range provides a cost-effective and flexible solution, with high levels of mechanical and electrical stability.

Photoelectric Sensor

A simple and secure design enables a watertight and dustproof seal to any standard M5 interface. The sensors are made with a robust Stainless Steel 316 case, sealed to IP67, making them well-suited to manufacturing and industrial automation operations.

Product codes: SLLP3002M5, SLDP3002M5, SLLN3002M5, SLDN3002M5, SLLP4002M5, SLDP4002M5, SLLN4002M5, SLDN4002M5, SLLP3002CL, SLDP3002CL, SLLN3002CL, SLDN3002CL, SLLP4002CL, SLDP4002CL, SLLN4002CL, SLDN4002CL

For more information, visit https://www.bulgin.com/en/products/range/sensors.html.