The proximity sensor is a device with the ability to perceive the proximity of an object. It uses the displacement sensor to recognize the proximity of the object by using the sensitive characteristic of the approaching object, and outputs the corresponding switch signal.
Therefore, the proximity sensor is usually called a proximity switch. It is a general term for sensors that replace the contact detection method and do not need to touch the detected object. It can detect the movement and existence of the object and convert it into an electrical signal.
The proximity sensor can detect in a non-contact manner, and will not wear and damage the detection object;
The proximity sensor adopts a non-contact output mode, which prolongs the service life of the sensor (except the magnetic type), and adopts a semiconductor output, which has no effect on the service life of the contact;
Different from the light detection method, the proximity sensor can be used in an environment with water and oil, and it is hardly affected by the dirt, oil, water, etc. of the detection object during detection;
Compared with contact switches, proximity sensors can achieve high-speed response;
The proximity sensor can be used in a wide temperature range;
The proximity sensor is not affected by the color of the detected object. Because the proximity sensor detects changes in the physical properties of the detected object, it is hardly affected by the surface color.
For detection bodies of different materials and different detection distances, different types of proximity switches should be selected to make it cost-effective in the system. For this reason, the following principles should be followed in the selection:
When the detection body is made of metal materials, a high-frequency oscillation type proximity switch should be used. This type of proximity switch is the most sensitive to the detection of iron-nickel and A3 steel detection bodies.
When the detection body is non-metallic materials, such as wood, paper, plastic, glass and water, etc., capacitive proximity switches should be used.
When long-distance detection and control are required, photoelectric proximity switches or ultrasonic proximity switches should be used.
When the detection body is metal and the detection sensitivity is not high, low-cost magnetic proximity switches or Hall-type proximity switches can be used.
Proximity sensors are mainly used to detect the displacement of objects, and are widely used in aviation, aerospace technology and industrial production:
In daily life, such as hotels, restaurants, garages, automatic doors, automatic hot air blowers have applications.
In terms of security and anti-theft, such important places as data archives, museums, and vaults are usually equipped with anti-theft devices composed of various proximity switches.
In measurement technology, proximity switches can be used to measure length and position;
In control technology, such as displacement, velocity, acceleration measurement and control, a large number of proximity switches are also used