Proximity sensors
The inductive sensor
An inductive sensor can detect metal objects because they are electrically conductive. The inductive sensor has an oscillator. This oscillator creates an electromagnetic field. The field is specifically directed in a specific direction by the specific construction method. An evaluation unit observes the magnetic field closely and reacts to any change to it.
However, an inductive sensor can only react to metallic materials. This means that this form of sensors cannot be used in all areas. However, an inductive sensor also has an advantage: it is usually a bit cheaper than other sensor models. There are many uses in factory automation.
The capacitive sensor
A capacitive sensor has a much wider range of applications than the inductive. In principle, a capacitive proximity sensor works like a capacitor. If an object is inserted into an electric field, the capacity changes. The sensor responds to this change. This is how he recognizes the approach of the object.
It is also not important whether this object conducts electricity or not. Even liquids are detected by a capacitive proximity sensor, as are granular and powdered substances. These can be plastics, for example, but also wood or stone, oil, water and cement.
Sensor ultraschall
Unlike the ones already mentioned, ultrasonic sensors do not react to a specific material. This special form of the proximity sensor emits an ultrasonic signal and then captures objects based on the reflection of this signal. Ultrasound is a sound that has frequencies above the human hearing frequency range. These are frequencies from about 16 kilohertz.
light barrier
A light barrier is a system that detects the interruption of a light beam. Disposable light barriers consist of a light beam source that acts as a transmitter on one side. and from a sensor that receives the radiation at the other end. If the signal is interrupted, the sensor emits an electrical signal. In the case of a reflective light barrier, on the other hand, the transmitter and receiver are in the same housing.
With this sensor technology, automatic devices can detect moving objects without touching them. Such an approximation sensor can be attached to, for example, automatically closing doors. The sensor may detect obstacles when closing or opening the door. However, a light barrier can also detect unauthorized intruders and trigger an alarm.