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Writer's pictureElectro Automation Industries

Fundamentals of Photoelectric Sensors

In the evolving world of automation and robotics, photoelectric sensors have proven to be vital components in numerous applications. Light-based sensors are widely used in industrial processes for object detection, making them a popular choice in various applications.



These sensors utilize light and electronic circuitry to detect changes in light properties, enabling reliable object detection. This introduction provides a basic understanding of photoelectric sensors, setting the stage for further exploration of their structure, mechanism, types, applications, and benefits.



Fundamentals of Photoelectric Sensors
Fundamentals of Photoelectric Sensors

Fundamentals of Photoelectric Sensors


In the evolving world of automation and robotics, photoelectric sensors have proven to be vital components in numerous applications. Light-based sensors are widely used in industrial processes for object detection, making them a popular choice in various applications.



These sensors utilize light and electronic circuitry to detect changes in light properties, enabling reliable object detection. This introduction provides a basic understanding of photoelectric sensors, setting the stage for further exploration of their structure, mechanism, types, applications, and benefits.



Fundamentals of Photoelectric Sensors
Fundamentals of Photoelectric Sensors


What is Photoelectric Switch?


A photoelectric switch is a type of sensor that uses light waves to detect the presence or absence of an object. It essentially operates on the principle of the photoelectric effect, where light is used to generate an electrical signal.


The switch includes an LED light source and a light-sensitive receiver, such as a photodiode or phototransistor. Object interruption or reflection of light triggers the receiver to open or close the electrical circuit.


Photoelectric switches are versatile tools used in industrial automation for object counting, presence detection, and safety systems. They are appreciated for their non-contact nature, quick response time, and ability to work over relatively long distances.


Background Suppression Sensors



Understanding Background Suppression in Photoelectric Sensors


Background suppression is a concept that is commonly employed in photoelectric sensors, particularly in the diffuse sensor type. Background suppression technology enables the sensor to focus on detecting objects within a specific range by ignoring the background.

The sensor sets a cutoff distance, beyond which no objects are detected, regardless of their size or reflectivity. It enables focusing on the desired object or area while ignoring background elements that could trigger the sensor.



The background suppression sensor uses the principle of triangulation to achieve this. The light emitted by the sensor is reflected back from the object into a receiver. Based on the angle of the returned light, the sensor can estimate the object’s distance.



How Background Suppression Works



Background suppression in a photoelectric sensor works by utilizing a unique optical arrangement and triangulation principle. When the sensor emits a light beam, it reflects off the object and returns to the sensor. The angle of this reflected light varies based on the distance of the object from the sensor.


Inside the sensor, a lens focuses this reflected light onto a position-sensitive detector (PSD). The PSD is an analog device that can measure the ‘position’ of the incoming light. If the object is close, the light hits one part of the detector, and if the object is farther away, it hits a different part.



Applications and Benefits of Background Suppression


Background suppression in photoelectric sensors is incredibly useful in several applications and comes with numerous benefits:


Packaging and Material Handling: Background suppression sensors accurately detect products in diverse product lines, regardless of color or background interference.

Automated Assembly Lines: These sensors effectively detect target parts amidst a dynamic environment, ignoring background distractions.


Robotic Arms and AGVs: Used in robotic arms and Automated Guided Vehicles (AGVs), these sensors help to avoid collision by distinguishing objects from the background.


As for the benefits, these sensors:

Improve Accuracy: They drastically improve the accuracy of object detection by ignoring the background.

Versatility: They can detect objects of varying colors, reflectivities, and surfaces.

Compact and Economical: As the emitter and receiver are housed in the same unit, the installation, and alignment become easier and cost-effective.

Reliability: They provide reliable detection in situations where the background can interfere with the sensing process.

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