Diffuse PEC Sensor (Diffuse Photoelectric Sensor)
A Diffuse PEC Sensor (Diffuse Photoelectric Sensor) works by emitting a beam of light directly toward the product on the conveyor. When the light hits the object, it reflects into the sensor, confirming that the item is present. The process is simple: the sensor sends out light, the light strikes the object, and the returning reflection allows the sensor to register detection.
One of the main advantages of diffuse PEC sensors is that they do not require a reflector, making installation easy on the sides of a conveyor. They are excellent for detecting parcels, boxes, totes, and general goods, especially within short-range applications. However, like any sensor type, they have some limitations. Reflective or shiny surfaces can occasionally interfere with accurate detection, and their sensing range is typically shorter than retro-reflective or through-beam alternatives.
We commonly use diffuse PEC sensors on driven roller conveyors where product presence needs to be monitored, on packing lines where operators manually remove items, and in shorter conveyor zones. They perform particularly well in light to medium industrial environments. Overall, diffuse sensors offer reliable detection and remain a cost-effective solution for the majority of standard conveyor systems.
Retro-Reflective PEC Sensors
A Retro-Reflective PEC Sensor (Reflector Type) operates by sending a beam of light toward a reflector positioned opposite the sensor. The beam returns consistently to the sensor, creating a stable signal. When a product passes between the sensor and the reflector, the beam is interrupted, and the sensor registers the detection.
The way it works is straightforward: the sensor emits a light beam, the reflector bounces that beam back, and the sensor continuously receives it until something blocks the path. As soon as the beam is broken, the system identifies that a product is present.
Retro-reflective PEC sensors offer several advantages. They provide a longer detection range, perform reliably in dusty or outdoor environments, and work well with dark or low-reflection surfaces that diffuse sensors might struggle with. They are also easy to align, requiring only a reflector rather than wiring on both sides of the conveyor. However, there are a few limitations to consider. Products can sometimes unintentionally reflect the light if they have highly reflective surfaces, and the reflector must be kept clean to maintain accuracy.
We typically use retro-reflective sensors on longer roller conveyor zones, high-speed driven roller conveyors, and in packaging, logistics, and warehouse operations. They are also ideal in areas where dust or debris might disrupt diffuse sensors and for detecting irregularly shaped goods. In our experience, retro-reflective PEC sensors are among the most dependable and versatile options for industrial conveyor systems.