Classification of common sensors and their functions

What is a sensor? Sensor is a device or device that can feel the specified measured signal and convert it into usable output signal according to a certain rule. In modern industrial production especially in the process of automatic production, to use a variety of sensors to monitor and control the various parameters in the production process, make the equipment work in the normal state or the best state, and make the product to achieve the best quality. Therefore, it can be said that without many good sensors, modern production will lose the foundation. There are many kinds of sensors, the last article I give you a summary of the main characteristics of the sensor, the following I put the common types of sensors summed up to bring you, in order to provide reference for your future application.

1, resistance sensor

Resistance sensor is to be measured, such as displacement, deformation, force, acceleration, humidity, temperature and other physical quantities into resistance value such a device. There are mainly resistance strain type, piezoresistive type, thermal resistance, thermal sensitive, gas sensitive, humidity sensitive resistance sensor parts.

2, frequency conversion power sensor

The frequency conversion power sensor carries out AC sampling of the input voltage and current signal, and then connects the sampled value to the digital input secondary instrument through the transmission system such as cable and optical fiber. The digital input secondary instrument calculates the sampled value of voltage and current. Parameters such as voltage RMS, current RMS, fundamental voltage, fundamental current, harmonic voltage, harmonic current, active power, fundamental power, and harmonic power can be obtained.

3, weighing sensor

Weighing sensor is a force to electricity conversion device which can convert gravity into electric signal. It is a key component of electronic weighing apparatus. There are many kinds of sensors that can realize the force to electricity conversion. The common ones are resistance strain type, electromagnetic force type and capacitance type. Electromagnetic force type is mainly used for electronic balance, capacitive type is used for part of electronic crane scale, and the vast majority of weighing products use resistance strain type weighing sensor. The resistance strain type weighing sensor has the advantages of simple structure, high accuracy, wide application, and can be used in relatively poor environment.

4, resistance strain sensor

The resistance strain gauge in the sensor has the strain effect of metal, that is, the mechanical deformation occurs under the action of external force, so that the resistance value changes correspondingly. Resistance strain gauges are mainly metal and semiconductor two types, metal strain gauges have wire type, foil type, film type. The semiconductor strain gauge has the advantages of high sensitivity (usually tens of times of the wire type, foil type), small transverse effect and so on.

5, piezoresistive sensor

Piezoresistive sensor is based on the piezoresistive effect of semiconductor material on the semiconductor material substrate by diffusion resistance device. The substrate can be directly used as a measuring sensor, and the diffusion resistance is connected into a bridge form in the substrate. When the substrate is deformed by external force, the resistance values will change, and the bridge will produce corresponding unbalanced output. The substrate (or diaphragm) materials used as piezoresistive sensors are mainly silicon and germanium. Silicon piezoresistive sensors made of silicon as sensitive materials are paid more and more attention by people, especially the solid piezoresistive sensors used to measure pressure and speed are the most common

6, thermal resistance sensor

Thermal resistance temperature measurement is based on the property that the resistance value of metal conductor increases with the increase of temperature. Most thermal resistors are made of pure metal materials. Platinum and copper are the most commonly used materials at present. In addition, materials such as nickel, manganese and rhodium have been used to make thermal resistors. It is mainly used to measure temperature and temperature-related parameters by the characteristic that resistance value changes with temperature. This kind of sensor is suitable for high temperature detection accuracy.

7, laser sensor

A sensor that uses laser technology to make measurements. It consists of laser, laser detector and measuring circuit. Laser sensor is a new type of measuring instrument, it has the advantages of non-contact remote measurement, fast speed, high precision, large range, anti light, electric interference ability. When the laser sensor works, the laser pulse is first fired by the laser emitting diode aiming at the target. After the laser is reflected by the target, the laser is scattered in all directions, and part of the scattered light returns to the sensor receiver, which is received by the optical system and imaged to the avalanche photodiode.

8. Hall sensor

Hall sensor is a kind of magnetic field sensor based on Hall effect, widely used in industrial automation technology, detection technology and information processing. Hall effect is a basic method to study the properties of semiconductor materials. Hall coefficient measured by Hall effect experiment can be used to judge the conductivity type, carrier concentration and carrier mobility of semiconductor materials.

9. Temperature sensor

The temperature sensor is mainly based on the principle that the resistance value and the potential of the thermocouple change regularly with different temperatures. We can get the temperature value we need to measure. Temperature sensor is not only a wide variety, and the combination of various forms, should be selected according to different places suitable products.

10, wireless temperature sensor

The wireless temperature sensor changes the temperature parameters of the control object into electrical signals, and sends wireless signals to the receiving terminal to detect, regulate and control the system. It can be directly installed in the junction box of general industrial thermal resistance and thermocouple, and constitute an integrated structure with field sensing elements. Usually and wireless relay, receiving terminal, communication serial port, electronic computer and other supporting use, so not only save the compensation wire and cable, but also reduce the signal transmission distortion and interference, so as to obtain high precision measurement results.

11, smart sensor

The function of intelligent sensor is proposed by simulating the coordinated movements of human senses and brain, combined with the research and practical experience of testing technology for a long time. Is a relatively independent intelligent unit, its appearance on the original hardware performance harsh requirements to reduce, and rely on software help can make the performance of the sensor greatly improved.

12, light sensor

Photosensitive sensor is one of the most common sensors, it has a wide variety, mainly: photocell, photomultiplier tube, photoresistor, photosensitive transistor, solar cell, infrared sensor, ultraviolet sensor, optical fiber photoelectric sensor, color sensor, CCD and CMOS image sensor. It is sensitive to wavelengths around visible light, including infrared and ultraviolet wavelengths. Light sensor is not only limited to the detection of light, it can also be used as a detection component of other sensors to detect many non-electric quantity, as long as these non-electric quantity into the change of optical signal can be. Optical sensor is one of the sensors with the largest output and the most widely used at present. It plays a very important role in automatic control and non-electric measurement technology.

13. Visual sensor

A visual sensor is one that has the ability to capture light from an entire image in thousands of pixels. The sharpness and delicacy of the image is often measured by resolution and expressed as the number of pixels. Vision sensors have thousands of pixels that capture light from an entire image, and the sharpness and delicacy of the image is usually measured by resolution, expressed as the number of pixels.

14. Displacement sensor

Displacement sensor is also called linear sensor, which converts displacement into electric quantity sensor. Displacement sensor is a linear device belonging to metal induction, the role of the sensor is to convert a variety of measured physical quantity into electricity. It is divided into inductive displacement sensor, capacitive displacement sensor, photoelectric displacement sensor, ultrasonic displacement sensor, Hall displacement sensor.

15. Grating sensor

Measuring grating is usually used in digital detection system to detect high precision linear displacement and angular displacement. It is a kind of detection device widely used in CNC machine tools. The spatial resolution of the grating sensor can generally reach about 1μm, the length of a single grating can reach more than 600mm, the main grating can be splicing, and the measuring range can reach more than a few meters.

16, infrared sensor

Infrared sensor is a sensor that uses the principle of thermocouple to detect infrared radiation by the physical effect presented by the interaction between infrared radiation and substances. In most cases, it uses the electrical effect presented by this interaction. Measuring the difference between the target and the sensor or the object and the environment temperature, the principle of the thermocouple is that two different metal A and B constitute a closed loop, when the temperature of the two contact ends are different (T>To), the loop generates thermoelectric potential Eab, where T is called the hot end, working end or measuring end, To is called the cold end, free end or reference end. A and B are called thermal electrodes. The size of the thermoelectric potential is determined by the contact potential (also known as the Bertie potential) and the thermoelectric potential (also known as the Thomson potential).

17, vacuum sensor

The vacuum degree sensor is produced by advanced silicon micromachining technology. The absolute pressure transmitter is made of integrated silicon pressure resistance sensor as the core component of the sensor. Due to the vacuum reference pressure chamber formed by silicon-silicon direct bonding or silicon-Pyrex glass electrostatic bonding, and a series of stress-free packaging technology and precision temperature compensation technology, Therefore, it has the outstanding advantages of excellent stability and high precision, and is suitable for the measurement and control of absolute pressure under various circumstances.

18. Pressure sensor

Pressure sensor is one of the most commonly used sensors in industrial practice, which is widely used in various industrial automatic control environment, involving water conservancy and hydropower, railway traffic, intelligent buildings, production automatic control, aerospace, military, petrochemical, oil Wells, electric power, ships, machine tools, pipelines and other industries.

19, ultrasonic distance sensor

Ultrasonic distance sensor using ultrasonic echo ranging principle, the use of accurate time difference measurement technology, detect the distance between the sensor and the target, the use of small Angle, small blind area ultrasonic sensor, with accurate measurement, no contact, waterproof, anti-corrosion, low cost and other advantages, can be used in liquid level, level detection, unique liquid level, material level detection method, It can guarantee a stable output in the case of foam or large shaking at the liquid level and difficult to detect echoes.

20. Capacitive level sensor

Capacitive level sensor is composed of capacitive sensor and electronic module circuit. It is based on two-wire 4~20mA constant current output. After conversion, it can be output by three-wire or four-wire, and the output signal forms standard signals such as 1~5V, 0~5V, 0~10mA. The capacitance sensor consists of an insulated electrode and a cylindrical metal container containing a measuring medium. When the material level rises, because the dielectric constant of non-conductive material is obviously less than the dielectric constant of air, so the capacitance changes with the height of the material.

21. Antimony electrode acidity sensor

Antimony electrode acidity sensor is an industrial online analysis instrument which integrates PH detection, automatic cleaning and electrical signal conversion. It is a PH measuring system composed of antimony electrode and reference electrode. In the tested acidic solution, the potential difference between the metal antimony surface and antimony trioxide will be formed due to the formation of antimony oxide layer on the surface of the antimony electrode. The magnitude of the potential difference depends on the concentration of the three antimony oxide, which corresponds to the moderation of hydrogen ions in the acidic solution under test.

22, conductance sensor

It is a flow meter (integrated sensor) that indirectly measures the ion concentration by measuring the conductivity value of the solution. It can continuously detect the conductivity of the aqueous solution in the industrial process online. Because the electrolyte solution is as good a conductor of electricity as the metal conductor, the current flowing through the electrolyte solution must have resistance and conform to Ohm's law. However, the resistance temperature characteristic of liquid is negative, which is opposite to that of metal conductor. To distinguish it from metallic conductors, the conductivity of electrolyte solutions is expressed in terms of conductance (reciprocal of resistance) or conductivity (reciprocal of resistivity). When two mutually insulated electrodes form a conductance pool, if the solution to be tested is placed between them, and the constant voltage alternating current is applied, a current loop is formed. If the voltage and electrode size are fixed, there is a certain functional relationship between the circuit current and the conductivity.