Capacitive Proximity Sensor
Capacitive Proximity Sensor introduction
The capacitive sensor, also known as a capacitive displacement sensor, is capable of detecting a wide range of different materials, regardless of whether the target object is conductive or non-conductive, without making physical contact. Lorentzzi® excels in producing high-quality capacitive sensors of all types. In terms of output options, we offer 2-wire AC output, 3-wire and 4-wire NPN output, 3-wire and 4-wire PNP capacitive sensors, as well as analog output sensors. In terms of shape, we provide M8, M18, M30 cylindrical, and flat sensors.
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Frequently asked questions
A capacitive sensor consists of dielectric plate, oscillator, trigger circuit and output circuit 4 parts. It is a non-contact switch that can detect not only metallic objects but also non-metallic objects. The working principle is that it uses an electrostatic field to detect the target object. When an object is within its sensing range, it will see the object as another conducting plate. At the same time, the capacitance of an oscillator inside the sensor will change, when this change reaches a level, the trigger circuit will activate the output circuit, making it from NO to NC or NC to NO.
A capacitive sensor composition is as following:
Capacitive sensors of different models and shapes have varying sensing ranges. Typically, the sensing distance ranges from a minimum of 2.0mm to a maximum of 25.0mm. As the housing of the sensor increases in size, the sensing distance also extends.
According to the working principle of capacitive sensors, there are three types: variable pole distance (d) type (also known as variable gap type), variable area (A) type, and variable dielectric constant (ε) type. The first type is used to measure displacement. The second type can measure dimensions, angles, and displacement. The third type can be utilized to measure liquid level, material thickness, and more.
As capacitive sensors utilize capacitance changes to detect objects, they are capable of detecting various types of materials without any issues. Therefore, capacitive sensors can be used for applications such as plastic detection, water level measurement, liquid level measurement, distance measurement, and more.
There are 4 differences between capacitive sensor and inductive sensor.
The working principles are different: inductive proximity sensors use eddy effects in the magnetic field for detection, while capacitive sensors use changes in oscillator capacitance to identify if an object is approaching or not.
The detection capabilities for different materials are also different: capacitive sensors can detect any object, whether it is conductive or non-conductive. On the other hand, inductive sensors can only detect conductive objects. As a result, capacitive sensors have a wider range of applications. However, if the intention is to solely detect metal objects, an inductive sensor is a suitable choice.
The detection distances also differ: inductive sensors are suitable for smaller detection ranges, typically ranging from a few millimeters to a few centimeters. In contrast, capacitive sensors can detect larger ranges, extending up to several meters.
In terms of cost, capacitive sensors are generally priced higher than inductive sensors. This is because producing capacitive sensors requires a more complex manufacturing process and involves more components than inductive sensors.
Please see the below electronic symbols for all the sensors: