What Is a Proximity Sensor?

Proximity sensors are a general term for sensors that replace contact detection methods such as limit switches and detect objects without contacting the detection object. It can detect the movement information and presence information of the object and convert them into electrical signals. The detection methods switched to electrical signals include a method using eddy current generated in the metal body of the detection object caused by electromagnetic induction, a method of changing the capacity of the electrical signal due to the approach of the detection body, a method of sharpening and a guide switch .

Proximity sensors are devices that have the ability to sense the proximity of objects. It uses the sensitivity characteristics of displacement sensors to approach objects to identify the proximity of objects and outputs corresponding switching signals. Therefore, the proximity sensor is often referred to as a proximity switch. ^[1]

Detection principle of inductive proximity sensor

The magnetic loss caused by the eddy current generated on the surface of the conductor is detected by the influence of an external magnetic field. A method of detecting an impedance change caused by an eddy current generated by a metal body of a detection body by generating an alternating magnetic field in the detection coil.

In addition, as another method, an aluminum detection sensor that detects a frequency phase component and an all-metal sensor that detects only an impedance change component through a working coil are also included.

On the surface of the test object side and the sensor side,

Since it can be detected in a non-contact manner, it will not wear or damage the detection object.

Since the contactless output method is used, the lifetime is extended (except for the magnetic type). The semiconductor output is used, which has no effect on the contact life.

Unlike the light detection method, it is suitable for use in water and oil and other environments. The detection is hardly affected by stains, oil, and water. Also includes

Proximity sensors are mainly used to detect the displacement of objects and are widely used in aviation, aerospace technology and industrial production. It is used in daily life, such as automatic doors and automatic heat fans in hotels, restaurants, and garages. In terms of security and anti-theft, such as data archives, accounting, finance, museums, vaults, etc., anti-theft devices composed of various proximity switches are usually installed. In the measurement technology, the measurement of length and position; in the control technology, such as the measurement and control of displacement, speed, acceleration, there are also a large number of users close to the switch. ^[1]