Hall element andhall sensor The production of is the largest.It is mainly used forBrushless DC motor(Hall motor), this motor is used for tape recorders, video recorders, XY recorders, printers, record players and ventilation fans in instruments.In addition, Hall elements and Hall sensors are also used to measure speed, flow, flow rate and to make Gauss meters, galvanometers, power meters and other instruments.
Magnetic sensor is an important part of sensor products. With the development of magnetic sensor technology in China, its product category and quality will be further developed and improved. The large and wide range application fields such as automobiles and civil instruments will be made in China,current sensor Gauss meters and other products have begun to enter the international market, and the gap with foreign products is rapidly narrowing.
Chinese name
Magnetic sensor
Role
Sense the existence or magnetic strength of magnetic objects (within the effective range)
Purpose
For brushless DC motor (Hall motor)
On behalf of manufacturer
Asahi Kasei, Toshiba, Institute of Semiconductor, Chinese Academy of Sciences, Shenyang Institute of Instrument Science, Nanjing Zhongxu Microelectronics Co., Ltd
As the name implies, it is to perceive the existence of magnetic objects or magnetic strength (within the effective range)magnetic material In addition to permanent magnets, it also includes paramagnetic materials (iron, cobalt, nickel and other alloys), which of course can also include sensing the magnetic field around energized (DC, AC) wire bundles or wires.
1、 In the traditional magnetic detection, the inductance coil is first used as the sensing element.The characteristic is that it does not need to be electrified in the coil, and it is generally only sensitive to the moving permanent magnet or current carrier.Later, it developed into an oscillating slot circuit composed of coils.Such as mine detector, metal foreign object detector, magnetic flux meter for measuring magnetic flux, etc. (magnetic flux gate, vibrating sample magnetometer).
2、 Hall sensor
hall sensor
Device made according to Hall effect.
Hall effect: when the electrified carrier is subjected to the external magnetic field perpendicular to the carrier plane, the carrier is subject to the Lorentz force and tends to gather towards both sides. Because of the accumulation of free electrons (more at one side and less at the same time), the potential difference is formed, and this effect is more significant in semiconductor materials prepared by special processes.Thus a Hall element is formed.The early Hall effect material Insb.In order to enhance the sensitivity to magnetic field, semiconductor IIIV element group has been applied in materials.In recent years, in addition to Insb, there are silicon substrates as well as gallium arsenide.Hall devices are made into full bridge devices due to their working mechanism, and their internal resistance is about 150 Ω~500 Ω.yesLinear sensorThe working current is about 2~10mA, and the constant current power supply method is generally adopted.
The typical working current of Insb and silicon substrate Hall devices is 10mA.Gallium arsenide typically operates at 2 mA.As a low and weak magnetic field measurement, we hope that the lower the working current required by the sensor itself, the better.Because there is a magnetic field around the power supply, errors are introduced to varying degrees.In addition, the sensor is very sensitive to temperature and has a self heating problem due to the large current.(Temperature rise) will cause zero drift of the sensor.In addition to the compensation circuit attached to these aspects, the materials are also constantly improved.
hall sensor There are mainly two categories, one is switch type device, the other is linear Hall device. The former is greater than the latter in terms of structure (variety), consumption and output.The response speed of Hall device is about 1us.
3、 Magnetoresistive sensor
Magnetoresistive sensor,Magnetic diodeIt is another kind of magnetic sensor derived from Hall sensor.The semiconductor materials used are roughly the same as Hall's.However, the mechanism of this kind of sensor to the magnetic field is different. The direction of carrier movement in the sensor is in the same plane with the detected magnetic field.By the way, Hall effect and magnetoresistance effect coexist.When manufacturing Hall devices, efforts should be made to reduce the influence of magnetoresistive effect, while when manufacturing magnetoresistive devices, efforts should be made to avoid Hall effect (in the calculation formula, they are mutually nonlinear terms).In the application of magnetoresistive devices, the control of temperature drift is also the main contradiction. In the preparation of devices, magnetoresistive devices are different from Hall, so the early products are single magnetoresistance.Due to the large temperature drift, single arm (two magnetoresistors in series) is mainly made to compensate for temperature drift.There are also full bridge products, but the usage (purpose) is slightly different from Hall devices.It is reported that the response speed of the magnetoresistive device is the same as that of Hall 1 uS.
Because the working mechanism of the magnetoresistive sensor is different from Hall, the power supply is also different. Instead, it uses a constant voltage source (but also requires a certain current) to supply power.When the following circuits are different, the requirements for the stability of power supply and internal noise are different.
4、 Problems in the application of magnetic sensors
Volume problem of magnetic sensor (unit):
The magnetic sensor is designed and manufactured to detect the magnetic field. The general concept of detection is to measure the magnetism of a point in the magnetic field.The definition as a point is infinitesimal in geometry.In magnetic field detection, because the area, volume and gap size of the magnetic field are limited, we hope that the smaller the area of the magnetic sensor is compared with the measured magnetic field area, the more accurate it will be.In magnetic field imaging technology, the smaller the component volume, the more pixels will be collected in the same area.The higher the resolution and definition.In the surface magnetic field measurement and the detection of multistage magnets, in the magnetic grid ruler, there must be such a requirement.From the working mechanism of the magnetic sensor, in order to improve the sensitivity, there are corresponding requirements for the geometric size of the geometric shape in the magnetic field, which is contradictory to the requirements of "point".According to the technical exchange with foreign experts, in 1999, Russian experts said that they had made a probe with a volume of 0.6mm (which was jointly made by several research institutes).There are also corresponding products in the United States, which sell for about $70 each.There is no other report on whether it is the highest level.
Product features
Announce
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1. The application of integrated circuit technology, the silicon integrated circuit technology is applied to the magnetic sensor to make an integrated magnetic sensor.
2. The successful development of InSb thin film technology has led to a sharp increase in the capacity of Hall devices and a sharp decrease in the cost.
3. The strong magnet alloy films have been widely used, and various magnetoresistance devices have emerged, which have a wide range of applications.
4. The research and development of giant magnetoresistance multilayer films and the high sensitivity and high stability of new devices have attracted great attention of the scientific and technological personnel who develop the readout head of high-density recording disks.
5、Amorphous alloyThe application of materials, together with the application of basic devices, has greatly improvedMagnetic sensorPerformance.
6. The development and application of Ⅲ - V semiconductor heterostructure materials can form heterostructures through epitaxy technology and improve the performance of magnetic sensitive devices.[1]
Development status
Announce
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Current situation of magnetic sensors abroad
1. The common types of foreign magnetic sensors In terms of market share, the main types of foreign magnetic sensors are still Hall elements, magnetoresistive elements, and the recent giant magnetoresistive elements also have good development space.
2. The biggest characteristic of magnetic sensor application is non-contact measurement.
Hall element: magnetic field measurement, as the detection probe of Gauss meter (Tesla meter), current detection, as the primary element of current sensor/transmitter,DC brushless motor, used to detect the rotor position and provide excitation signals, and to measure the speed/revolution of integrated switch type Hall devices.
Strong magnet film magnetoresistance device: displacement sensor, mainly including linear long-distance displacement measurement of magnetic ruler,Angular displacement sensor, mainly used to measure the rotation angle, which is widely used in the automobile manufacturing industry.
Pulse transmitter is mainly used for flow detection and speed/revolution measurement, such as transmitter of electronic water meter and flowmeter.
Semiconductor magnetoresistive device: mainly used for weak magnetic field detection of InSb magnetoresistive device, mainly used for counterfeit money recognition pulse measurement, mainly used for speed/revolution measurement
Current situation of domestic magnetic sensors
1. The common types and characteristics of domestic magnetic sensors After more than 30 years of development, domestic magnetic sensors, in terms of the research and development of basic devices, except for the gap during the period of giant magnetoresistance, commonly used other magnetic sensors such as Hall elements,The type of domestic magnetic sensing devices used in the market, such as magnetoresistive elements, is also the same as that of foreign products. They are still Hall elements and magnetoresistive elements.
2. Representative manufacturer of domestic magnetic sensor components Hall element: Institute of Semiconductor, Chinese Academy of Sciences,Shenyang Instrument Science Research InstituteNanjing Zhongxu Microelectronics Co., Ltd., magnetoresistive device: Shenyang Institute of Instrument Science (Huibosi Binnis Co., Ltd.)
3. Application of magnetic sensors in China Current sensors: Twenty or thirty enterprises of different sizes in China, including Shenyang Institute of Instrument Science (Sibinnis), Southwest Institute of Automation, are producing and selling current sensors/transmitters, and their market competition has become fiercer.This field is the earliest, most popular and most mature field in the application of magnetic sensors in China. In the field of DC brushless motor, InSb Hall components are mainly used to detect the rotor position of DC brushless motor, and provide the excitation signal of stator coil current commutation. The annual demand is several hundred million, and the price is only about 0.3 yuan,This field is the field with the largest use of magnetic sensors, but there is no industrial production in China. Flow measurement field: low-power thin film magnetoresistive devices used for electronic water meters, electronic gas meters, flow meters and other flow signal sensors.Recently, this product was produced by Huibos Binnis Sensing Technology Co., Ltd. of Shenyang Institute of Instrument Science, with considerable market space. This field is the most promising emerging application field of magnetic sensors in China. It is in the growth stage of the market. Special measuring instrument: Gauss meter, used for magnetic field detection, has a large amount of use in the production and application of magnetic materials,In China, several companies, such as Shenyang Instrument Institute Sibinnis Co., Ltd. and Beijing Normal University, produce Gauss meters. Sibinnis Gauss meters have been exported to the United States in batches. In addition, domestic magnetic sensors are also used in rotational speed/revolution measurement, counterfeit note recognition and other fields, but have not formed a scale.Professor Sun Rentao mentioned that it is a great pity that domestic magnetic sensors have not entered the field of automobile production.
