Weighing sensor
Weighing sensor is a kind of to gravity into electrical signals and electrical switching device, the force is a key component of the electronic weighing apparatus.
Force can be implemented to electricity conversion there are many types of sensors, common resistance strain type, the electromagnetic type and condenser, etc. The electromagnetic type is mainly used for electronic balance, capacitor used in some electronic crane scale, and most of the instruments or resistance strain type weighing sensor is used for the product. Resistance strain type weighing sensor structure is simple, high accuracy, widely applicable, and can be used in a relatively poor environment. So the resistance strain type weighing sensor has been widely used in instruments.
The resistance strain sensor
Sensor of resistance strain slice with the strain effect of metal, which produces mechanical deformation under the action of external force, so that the resulting resistance value corresponding to change. Resistance strain gauge mainly has two types of metal and semiconductor, metal, metal wire and foil strain gauge type, diaphragm. Semiconductor strain gauge with high sensitivity (typically, wire, foil type of dozens of times), and the advantages of small transverse effect.
Piezoresistive sensor
Piezoresistive sensor is based on the piezoresistive effect of semiconductor materials in the semiconductor substrate device made by diffusion resistance. The substrate can be directly as a measuring sensors, diffusion resistance in substrate inscribed into bridge forms. When the substrate caused by external force and deformation, the resistance value will change, will produce corresponding unbalanced output bridge.
Is used as the substrate piezoresistive sensor (or diaphragm) materials mainly for silicon and germanium, silicon wafers for sensitive materials made of silicon piezoresistive sensors become more and more get the attention of the people, especially to measure the pressure and velocity of the most common solid piezoresistive sensor applications.
Thermal resistance sensors
Thermal resistance temperature measurement is based on the metal conductor resistance value increases with the increase of the temperature of the properties for temperature measurement. Thermal resistance are mostly made of pure metal materials, application at present most is platinum and copper, in addition, have begun to use the materials such as nickel, manganese and rhodium manufacturing thermal resistance.
Thermal resistance sensor resistance changes over temperature was mainly used this feature to measure temperature and parameters related to the temperature. In place of temperature detection accuracy is higher, this kind of sensor is more applicable. More extensive thermal resistance materials such as platinum, copper, nickel, and they have the temperature coefficient of resistance, good linear, stable performance, use temperature scope width, easy processing, etc. Used to measure - 200 ℃ ~ + 500 ℃ temperature.
Thermal resistance sensors classification:
1, NTC thermal resistor sensor:
This kind of sensor for negative temperature coefficient of the sensor, the sensor resistance decreases with the increase of temperature.
2, PTC thermal resistance sensors:
This kind of sensor for positive temperature coefficient of the sensor, the sensor resistance increases with the rise of temperature.
Laser sensor
Using laser technology measurement sensors. It consists of laser, laser detector and the measurement circuit. Laser sensor is a new type of measuring instrument, its advantage is that can realize non-contact distance measurement, fast speed, high precision, large range, optical, electrical interference resistance ability, etc.
Laser sensor is working, first by the laser diode laser pulse on target launch. After the target reflection laser scattering in all directions. Part of the scattered light to return to the sensor receiver, by the optical system imaging to the avalanche photodiode after receiving. Avalanche photodiode is a internal amplification function of optical sensors, so it is extremely weak light signal can be detected, and translate them into corresponding electrical signals.
Using a laser of high directivity and high monochromaticity, and high brightness characteristics of non-contact distance measurement can be realized. Laser sensor is often used in length (the ZLS (central authority - Px), distance (LDM4x), vibration (ZLDS10X), speed (LDM30x), azimuth measurements of physical properties, can also be used for detection and monitoring of atmospheric pollutants.
Hall sensor
Hall sensor based on hall effect produced a kind of magnetic field sensors, widely used in industrial automation technology, testing technology and information processing, etc. Hall effect is the basic method of research semiconductor material performance. By measuring hall coefficient of hall effect experiment, can judge the semiconductor material conduction type, carrier concentration and carrier mobility and other important parameters.
Hall sensor type can be divided into linear hall sensor and switch type two hall sensors.
Type 1, linear hall sensor is composed of hall element, linear amplifier and an emitter follower, it outputs analog.
2 hall sensor, switch mode by the voltage regulator, hall element, difference amplifier, schmidt triggers and output stage, the digital output.
Hall voltage changes along with the change of magnetic field intensity, the stronger the magnetic field, the higher the voltage, the weaker magnetic field, the lower the voltage. Hall voltage value is very small, usually only a few millivolts, but by the amplifier amplification in the integrated circuit, can make the output voltage amplification enough strong signal. If make the hall integrated circuit sensor role, need to use mechanical methods to change the magnetic field strength. Shown below method is to use a rotating impeller as a switch to control the magnetic flux, when the impeller vane in the air gap between the magnet and hall integrated circuit, the magnetic field deviates from the integration, the hall voltage disappears. In this way, the output voltage of the hall integrated circuit changes, can show the impeller drive shaft of a certain position, using the principle of work, can be the hall integrated circuit with function ignition timing sensor. The hall effect sensors are passive sensors, it must have a plus the power to work, this characteristic makes it can detect low speed operation.
The temperature sensor
1, at room temperature sensor: room temperature sensor is used to measure the environment of indoor and outdoor temperature, the tube temperature sensor is used to measure the tube wall temperature of evaporator and condenser. Room temperature sensor and the shape of the tube temperature sensor is different, but the temperature characteristic are basically identical. Use room temperature according to the temperature characteristic, divided into beauty pipe temperature sensor has two types: 1. The constant value of 4100 k B + / - 3%, benchmark resistance corresponding resistance is 25 ℃ and 10 k Ω plus or minus 3%. At 0 ℃ and 55 ℃ resistance tolerance about + / - 7%; Above and below 0 ℃ and 55 ℃, for different suppliers, the resistance tolerance will have certain difference. The higher the temperature, the smaller the resistance; The lower the temperature, the greater the resistance. The farther from 25 ℃, corresponding to the greater the resistance tolerance range.
2, exhaust temperature sensor: exhaust temperature sensors used to measure the top of the compressor exhaust temperature, constant value of 3950 k B + / - 3%, corresponding resistance at 90 ℃ for 5 k benchmark resistance Ω plus or minus 3%.
3, modules, temperature sensor, temperature sensor for measuring the frequency conversion module (IGBT or IPM) temperature, with the thermal model of the head is 602 f - 3500 - f, benchmark resistance corresponding resistance is 25 ℃ 6 k Ω plus or minus 1%. Several typical temperature corresponding resistance are: - 10 ℃ - (─) K Ω; 0 ℃ - > (─) K Ω; 50 ℃ - > (─) K Ω; 90 ℃ - > K Ω (─).
There are many kinds of temperature sensor, often use a thermal resistance: PT100, PT1000, Cu50, Cu100; Thermocouple: B, E, J, K, S, etc. Temperature sensor not only sort is various, and combination of various forms, should choose suitable products according to different places.
Temperature measuring principle: according to different resistance resistance, electric potential with the temperature of thermocouple regular changes in principle, we can get the need to measure the temperature.
Wireless temperature sensor
Wireless temperature sensor to control the temperature of the object parameters into electrical signals, and the receiving terminal sends wireless signals, to carry on testing, adjusting and control system. Can be directly installed in the general industrial thermal resistance, thermocouple junction box, and field sensors integration structure. And wireless relay, receiving terminal, usually use serial communications, electronic computer and accessories, this not only saves compensating wire and cable, and to reduce the signal distortion and interference, thus for the precision measurement results.
Wireless temperature sensor is widely used in chemical industry, metallurgy, petroleum, electric power, water treatment, pharmaceutical, food and other industries automation. For example: the temperature on the high voltage cable collection; Underwater environment such as temperature acquisition; The temperature on the moving object acquisition; Not easy attachment through space sensor data transmission; To reduce the wiring cost alone choose data acquisition scheme; No ac power data measurement of the workplace; Portable without a fixed site measurements.
Smart sensors
The function of intelligent sensor is action in coordination with the simulation of the human senses and the brain, the combination of testing technology for a long time study and practical experience. Is a relatively independent intelligent unit, it appeared on the original hardware performance required relief, and rely on software can help to greatly improve the performance of the sensor.
1, information storage and transmission, as the rapid development of intelligent distributed control system (SmartDistributedSystem), requirements for intelligent units have communication function, with two-way communication in the form of digital communication network, which is a key symbol of smart sensors. Smart sensors through test data transmitted or received instructions to achieve various functions. Gain Settings, compensation parameter setting, internal checking parameters Settings, test data output, etc.
2, since the compensation function and calculation -- for many years engaged in sensor engineering technical personnel has been developed for the sensor temperature drift and output nonlinear large compensation work, but have not fundamentally solve the problem. And since compensation and calculation function of intelligent sensor for the sensor and the nonlinear compensation of temperature drift opened up a new path. So, relax sensor processing precision requirements, as long as you can guarantee the repeatability of the sensor, microprocessor was used to test the signal is calculated by the software, several times with fitting and difference value to compensate the drift and nonlinear calculation method, which can obtain more accurate measurement results of pressure sensor.
3, self-test, self-calibration, self diagnosis function, ordinary requires periodic inspection and calibration of sensor and to ensure the accuracy of it enough in normal use, these jobs usually require that the sensor removed from using the site to the laboratory or inspection department. For on-line measuring sensor abnormal is not timely diagnosis. Using intelligent sensor is improved, the first since the diagnostic function is introspected when power on, diagnostic test to determine the component is trouble-free. Secondly according to the use of time can be online for correction, the microprocessor using the metrological characteristics within an EPROM data comparing to proofread.
4, sensitive composite function, observing the natural phenomenon, common audio signal, optical, electrical, thermal, mechanical, chemical, etc. Sensor measurement generally in two ways: direct and indirect measurement. And smart sensors with composite function, and can simultaneously measure the amount of a variety of physical and chemical, can comprehensively reflect the law of motion of the material information is given.
Photosensitive sensor
Photosensitive sensor is one of the most common sensor, its sort is various, mainly include: photocell, photomultiplier tubes, photosensitive resistance, light activated triode, solar cells, infrared sensors, ultraviolet sensors, optical fiber photoelectric sensor, colour sensor, CCD and CMOS image sensor, etc. The sensitive wavelengths in the visible light wavelength near, including infrared wavelength and ultraviolet wavelengths. Light sensor is not limited to light detection, it also can be used as a probe of other sensors and to test the many non-electricity, as long as these non-electricity converted to the change of the optical signals. Light sensor is the most current production, one of the most widely used sensors, it is in automatic control and non-electricity electric logging technology occupies very important position. The simplest photosensitive sensor [2] is photosensitive resistance, when photons hit joint, creates an electric current.
biosensor
The concept of biological sensors
Biosensor is to use biological activity material (enzymes, proteins, DNA, antibody and antigen, biological membrane, etc.) and the organic combination of physical and chemical transducer a cross discipline, is a kind of advanced biotechnology development essential detection method and monitoring method, also is rapid, trace analysis method of material at the molecular level. All kinds of biosensor has the following common structure: including one or several related biological activity material (biofilm) and are able to express biologically active signal is converted to electrical signals in the physical or chemical transducer (sensor), the two together, with the modern microelectronics and automation instrument technology and biological signal processing, constitute a variety of can use biosensors analysis device, instrument and system.
The principle of biosensors
Material by diffusion into the biological activity material under test, the molecular recognition and biological reaction, the information and then by the corresponding physical or chemical transducer into quantitative and can handle the electrical signals, then through secondary instrument amplifier and the output, can know the concentration in the object under test.
The classification of the biosensor
According to the sensors used in the life of the material classification, can be divided into: microbial sensors, sensor, sensor, cell sensor, enzyme sensor, DNA sensor and so on.
Classified according to the principle of the sensor device detection, can be divided into: thermal biosensor, field effect tube biosensor, piezoelectric biosensors, optical biosensors, acoustic wave biosensor, enzyme biosensor electrodes, copula biosensor, etc.
According to the biological material sensitive type of interaction between classification, can be classified as affinity and metabolic type two kinds.
Vision sensors
Working principle:
Visual sensor is to point to: from a whole image capture the light of several thousands of pixels, image clear and delicate degree of resolution is commonly used to measure, expressed as a number of pixels.
Visual sensor has a whole image capture the light from the thousands of pixels. Image clarity and delicate degree is usually measured by resolution, expressed as a number of pixels.
After image capture, vision sensors with the memory stored in the reference image comparison, to make analysis. For example, if a visual sensor is set to distinguish correctly inserted with eight of the bolt machine parts, the sensors know only seven of the bolt components should be rejected, bolts or misalignment of the components. In addition, whether the machine parts which position in the field of view, at no matter whether the part within the scope of the 360 - degree rotation, vision sensors can make judgments.
Areas of application:
The low cost and ease of use of visual sensor has attracted machine designers and process engineers integrate it into all kinds of used to rely on artificial, multiple photoelectric sensor, or no inspection application. Visual sensors, industrial applications including inspection, measuring, measurement, directional, flaw detection and sorting. Here is some application examples:
In car assembly plant, daub inspection by robot to the door frame plastic bead is continuous, if there is a correct width;
In the bottlers, check cap is properly sealed, filling level is correct, and no foreign bodies fall into the bottle before block;
In packaging production line, ensure that in the right place to paste the correct packing label;
The drugs packaging production line, inspection of aspirin tablets in blister packaging type to see if there is any breakage or missing tablets;
In metal stamping company, inspection at a speed of more than 150 pieces per minute stamping parts, more than 13 times faster than manual inspection.
Displacement sensor
Displacement sensor is also known as linear sensor, displacement sensor is converted to electricity. Displacement sensor is a device that belongs to the metal induction linear sensor is used to convert various measured quantities to power it is divided into inductive displacement sensor, capacitive displacement sensor, photoelectric displacement sensor, ultrasonic displacement sensor and hall displacement sensor.
In the conversion process, there are many physical quantities (such as pressure, flow rate, acceleration, etc.) often need to transform as the displacement, then the displacement transform into electricity. So the displacement sensor is a kind of important basic sensor. In the process of production, displacement measurement generally divided into two physical dimensions and mechanical displacement measurement. Mechanical displacement including linear displacement and angular displacement. According to the measured variable transformation, different kind of displacement sensor can be divided into analog and digital two kinds. Analog type can be divided into physical properties (such as spontaneous electric) and structured two kinds. Displacement sensor is commonly used in the majority with analog structured, including the potentiometer displacement sensor, inductive displacement sensor, selsyn, capacitive displacement sensor and electric eddy current displacement sensor and hall displacement sensor, etc. An important advantage of digital displacement sensor is to facilitate the signal directly into a computer system. This kind of sensor has been developing rapidly, the application is becoming more and more widely.
Pressure sensor
Pressure sensor led is the most commonly used in industrial practice of a sensor, its widely used in various industrial control environment, involved in water conservancy and hydropower, railway transportation, intelligent buildings, production control, aerospace, military industry, petrochemical, oil, electric power, ships, machine tools, pipe, and many other industries.
