Introduction to How Photoelectric Sensors Work and Their Applications

Introduction to Photoelectric Control

Photoelectric control, or photoelectric sensors, utilize a beam of light to detect the presence or absence of objects. They allow industrial automation systems, processes, and machinery to reliably detect items, parts, or other physical matter by interrupting the transmission of light to a receiving photo sensor.

How Photoelectric Controls Work

A basic photoelectric control consists of an emitter that produces a light beam (typically infrared) aimed at a receiver. When an object passes through the light beam, it prevents the receiver from detecting the light signal, which triggers the sensor and associated control system to take action.

There are two main types of photoelectric controls:

• Through Beam - The emitter and receiver are separate, with the light beam running between them. Any obstruction breaks the beam.
• Reflective - The emitter and receiver are housed in the same unit. The beam bounces off a reflector, with an obstruction preventing the reflected light from returning to the sensor.

Applications and Benefits

Photoelectric controls provide fast, accurate object detection critical for:

FAQs

What is the detection range of photoelectric sensors?

Most photoelectric sensors have a detection range of anywhere from a few millimeters up to around 10 meters. Long range photoelectric sensors using lasers can detect objects up to 100 meters away or more.

How fast can a photoelectric sensor respond?

Photoelectric sensors are very fast with response times as quick as 500 μs or 0.5 ms. High speed units can detect objects in microseconds, while longer range models may be in the few milliseconds range.

Will photoelectric sensors work with transparent objects?

Standard photoelectric sensors may struggle with transparent objects that do not fully obstruct the beam. However, specialized transparent sensors use precise timings and light refraction to reliably detect clear glass, plastic, liquids, and other transparent items.

Can a single photoelectric sensor have both emitter and receiver?

Yes, reflective type photoelectric sensors house both the emitter and receiver in a single unified housing. The emitted beam bounces off a reflector, with an obstruction detected when the reflected light does not return to the sensor.