There are many types of sensors And there are several types of proximity switches, sensors are a general term, and proximity switches are a category within sensors. Sensor: "A device or apparatus that can sense a specified measured object and convert it into a usable signal according to a certain pattern, usually composed of sensitive elements and conversion elements.

A sensor is a detection device that can sense the measured information and convert it into electrical signals or other required forms of information output according to certain rules, in order to meet the requirements of information transmission, processing, storage, display, recording, and control. It is the primary step in achieving automatic detection and control. Classification of sensors: Currently, there is no unified classification method for sensors, but there are three commonly used types: 1. According to the physical quantity of the sensor, it can be classified into sensors such as displacement, force, velocity, temperature, flow rate, gas composition, etc. 2. According to the working principle of the sensor, it can be classified into sensors such as resistance, capacitance, inductance, voltage, Hall effect, photoelectric, grating, thermocouple, etc. 3. According to the nature of the sensor output signal, it can be classified into switch type sensors that output switch values ("1" and "0" or "on" and "off"); Output as analog sensor; A digital sensor that outputs pulses or codes. Classification of sensors: 1. Classified by measured physical quantities, such as force, pressure, displacement, temperature, angle sensors, etc; 2. According to the working principle of sensors, they can be classified into: strain sensors, piezoelectric sensors, piezoresistive sensors, inductive sensors, capacitive sensors, photoelectric sensors, etc; 3. According to the way sensors convert energy: (1) Energy conversion types: such as piezoelectric, thermocouple, photoelectric sensors, etc; (2) Energy control type: such as resistive, inductive, Hall sensors, as well as thermistors, photoresistors, humidity sensors, etc; 4. According to the working mechanism of sensors, they can be divided into: (1) structural types, such as inductive and capacitive sensors; (2) Physical properties: such as piezoelectric, photoelectric, various semiconductor sensors, etc; 5. According to the form of sensor output signal: (1) Analog formula: Sensor output is an analog voltage quantity; (2) Digital: The sensor output is a digital quantity, such as an encoder type sensor. Among various sensors, there is a component that has the ability to "perceive" objects approaching it: displacement sensor. This type of sensor does not require contact with the detected object. When an object moves towards the displacement sensor and approaches a certain distance, the displacement sensor has "perception", which is usually called the "detection distance". A switch made using the sensitive characteristics of displacement sensors for approaching objects is called a proximity switch.

Because displacement sensors can be made according to different principles and methods, and different displacement sensors have different "perception" methods for objects, there are several common types of proximity switches: 1. Eddy current proximity switch (inductive proximity switch), 2. Capacitive proximity switch, 3. Hall proximity switch, 4. Optoelectronic proximity switch, 5. Pyroelectric proximity switch, 6. Other types of proximity switches (ultrasonic proximity switch, microwave proximity switch, etc.).