Principles and Differences of Capacitive and Inductive Proximity Sensors
Traditional detection method: contact limit switch
In the past, contact type limit switches were commonly used as detection methods for products. The limit switch is purely mechanical and achieves control effect by breaking the contacts through mechanical collision, without the need for power supply.
The birth of proximity sensors
Classification of proximity sensors
There are a wide variety of types of proximity sensors, including cylindrical, square, flat, ring, etc. However, based on the detection principle, they are generally divided into two types:
1、Inductive proximity sensor:
Based on the principle of electromagnetic induction, inductive proximity sensors have a fast response speed and can detect magnetic objects (such as iron), but the detection distance for non-magnetic objects (such as copper, aluminum, etc.) will be greatly reduced.
2、Capacitive proximity sensor:
The casing is generally made of polyethylene, and capacitive proximity switches can detect any material in a contact or non-contact manner. Some brands of capacitive proximity sensors can even adjust the detection distance by adjusting the sensitivity potentiometer, and are widely used in industries including wood, paper, glass, plastic, food, chemicals, and semiconductors.
Working principle of capacitive proximity sensor
A capacitor usually contains two electrode plates inside. When powered on, the two electrode plates directly generate voltage, forming a capacitor. At this time, any object entering the voltage range will change the capacitance between the electrode plates.
There is also a case where there is only a single electrode plate, in which case the other electrode plate is the ground. Capacitive proximity sensors commonly use unipolar capacitive plates. When an object is within the detection range, the capacitance changes and the signal is processed by an internal circuit to output an IO signal.
Working principle of inductive proximity sensor
Inductive proximity sensors operate based on the principle of electromagnetic induction. It consists of a core with coils and two electrodes mounted on the core. When a metal object or target approaches the sensor, it will change the magnetic field, causing a change in current between the electrodes, thereby driving the output signal.
Inductive proximity sensors are sensitive to metallic objects, but cannot effectively detect non-metallic objects.
During installation and use, sensors should be avoided from being exposed to strong magnetic fields or high temperatures to avoid affecting their performance.
When choosing sensors, appropriate models and parameters should be selected based on specific application scenarios and requirements.
In the past, contact type limit switches were commonly used as detection methods for products. The limit switch is purely mechanical and achieves control effect by breaking the contacts through mechanical collision, without the need for power supply.
The birth of proximity sensors
In 1958, Walter Pepperl and Ludwig Fuchs, the founders of Beckhoff, invented the world's first proximity switch in a laboratory. This innovation marks a new era of electronic proximity sensors.
Classification of proximity sensors
There are a wide variety of types of proximity sensors, including cylindrical, square, flat, ring, etc. However, based on the detection principle, they are generally divided into two types:
1、Inductive proximity sensor:
Based on the principle of electromagnetic induction, inductive proximity sensors have a fast response speed and can detect magnetic objects (such as iron), but the detection distance for non-magnetic objects (such as copper, aluminum, etc.) will be greatly reduced.
2、Capacitive proximity sensor:
The casing is generally made of polyethylene, and capacitive proximity switches can detect any material in a contact or non-contact manner. Some brands of capacitive proximity sensors can even adjust the detection distance by adjusting the sensitivity potentiometer, and are widely used in industries including wood, paper, glass, plastic, food, chemicals, and semiconductors.
Working principle of capacitive proximity sensor
A capacitor usually contains two electrode plates inside. When powered on, the two electrode plates directly generate voltage, forming a capacitor. At this time, any object entering the voltage range will change the capacitance between the electrode plates.
There is also a case where there is only a single electrode plate, in which case the other electrode plate is the ground. Capacitive proximity sensors commonly use unipolar capacitive plates. When an object is within the detection range, the capacitance changes and the signal is processed by an internal circuit to output an IO signal.
Working principle of inductive proximity sensor
Inductive proximity sensors operate based on the principle of electromagnetic induction. It consists of a core with coils and two electrodes mounted on the core. When a metal object or target approaches the sensor, it will change the magnetic field, causing a change in current between the electrodes, thereby driving the output signal.
Inductive proximity sensors are sensitive to metallic objects, but cannot effectively detect non-metallic objects.
During installation and use, sensors should be avoided from being exposed to strong magnetic fields or high temperatures to avoid affecting their performance.
When choosing sensors, appropriate models and parameters should be selected based on specific application scenarios and requirements.
