The sensor is a device that can convert physical quantities into electrical signals, which is an important part of modern industrial automation and informationization. The principle of the sensor is to use the basic principles of physics to convert the measured physical quantities into electrical signals, which are then processed by signal processing circuits to finally realize the monitoring and control of the measured physical quantities.
Classification of Sensors
Based on the different physical quantities measured, sensors can be divided into a variety of types, such as temperature sensors, pressure sensors, flow sensors, photoelectric sensors and so on. Among the most common sensors are temperature sensors and pressure sensors.
Principle of Temperature Sensor
Temperature sensor is a device that can measure the temperature of an object, which is based on the principle of converting the temperature of an object into an electrical signal by using the technology of thermistors, thermocouples or infrared rays.
Thermistor principle
Thermistor is a resistance element whose resistance value changes with temperature. When the temperature rises, the resistance value of the thermistor decreases; when the temperature decreases, the resistance value of the thermistor increases. Therefore, by measuring the change in resistance value of the thermistor, the temperature of the object to be measured can be determined.
Principle of thermocouple
Thermocouple is an electrode composed of two different metals, when the temperature of the two electrodes is different, it will produce thermal potential. By measuring the magnitude of the thermal potential, the temperature of the object being measured can be determined.
Infrared Principle
Infrared sensors are sensors that can determine the temperature of an object by measuring the infrared rays radiated from it. When the temperature of an object increases, more infrared rays are radiated, and by measuring the intensity of the infrared rays, the temperature of the object can be determined.
Principle of Pressure Sensor
A pressure sensor is a device capable of measuring the pressure of an object by converting the pressure of the object into an electrical signal using techniques such as resistive strain, piezoelectric effect or millimeter wave.
Principle of Resistive Strain
Resistive strain is a type of resistive element in which the resistance value varies with strain. When an object is subjected to pressure, strain occurs, which results in a change in the resistance value. By measuring the change in resistance value, the pressure on the object can be determined.
The principle of the piezoelectric effect
The piezoelectric effect is a phenomenon in which a substance, when subjected to pressure, produces a separation of electric charges. By measuring the magnitude of the charge, the pressure of an object can be determined.
Millimeter wave principle
The millimeter wave sensor is a sensor capable of determining the pressure of an object by measuring the reflected signal from its surface. When an object is pressurized, it causes the shape of its surface to change, which results in a change in the reflected signal. By measuring the change in the reflected signal, the pressure of the object can be determined.
Applications of Sensors
Sensors are used in a wide variety of fields, such as industrial automation, environmental monitoring, medical devices, transportation, and more. Here are a few common application scenarios.
Temperature Sensor Applications
Temperature sensors are widely used in various temperature control systems, such as air conditioners, refrigerators, ovens and other household appliances, as well as industrial heating equipment, heat treatment equipment and so on.
Pressure sensor applications
Pressure sensors are widely used in a variety of pressure control systems, such as automotive engine control, air compressor control, water pump control.
Photoelectric sensors
Photoelectric sensors are widely used in various automation control systems, such as automatic doors, vending machines, automated production lines.
Operating steps of sensors
The operating steps of sensors usually include the processes of installation, connection and calibration.
Installation
The installation location and mounting method of the sensor have a great impact on its measurement accuracy and service life. In general, the sensor should be installed on the surface of the object to be measured, avoiding contact with other objects, so as not to affect the measurement accuracy.
Connection
There are usually two ways to connect the sensor, one is directly connected to the control system, and the other is to connect through the signal converter. Regardless of the type of connection, it is necessary to ensure that the connection is stable and reliable.
Calibration
The calibration of the sensor is an important step to ensure its measurement accuracy. The method of calibration is usually to use a standard object for comparison and adjust the output signal of the sensor to achieve the purpose of accurate measurement.