[introduction] magnetometer is the equipment that can measure magnetic field size or way. They are in electronic product almost nowhere is absent. They may be used like your smartphone detect whether it is erect simple in that way, use those who measure Martian magnetic field possibly also like NASA complex in that way.

Magnetometer is the equipment that can measure magnetic field size or way. They are in electronic product almost nowhere is absent. They may be used like your smartphone detect whether it is erect simple in that way, use those who measure Martian magnetic field possibly also like NASA complex in that way.

Here, we reach the fundamental that knows magnetometer our to apply. In the following article, we will study the magnetometer of specific type carefully.

How does magnetometer work?

Magnetometer measures so called magnetic moment through indirect method normally. The magnetic moment of the closed circuit that has area A and voltaic I is a vector, its size is equal to I to multiply with A. This annulus road is equal to magnetic moment to multiply via the torque of all previous with magnetic field.

On maths, magnetic moment expresses as follows:

τ = torqueM = magnetic moment
B = exterior magnetic field

As vector, the direction of magnetic field and its amplitude are euqally important. The way that a few magnetometer can measure magnetic field and size (vector magnetometer) , and other magnetometer can measure its extent only (scalar quantity magnetometer) .

About the unit, international system (SI) unit is Am 2. However, it expresses with a lot of other units normally, for example $$frac{erg}{G}$$ , among them Erg is an energy unit, be equivalent to 10 -7 joule, g is a gauss.

Magnetometer and magnetic hysteresis curve

When magnetic field of magnetic material immerge is medium, its character can produce change. Be in according to these material bring to bear on after be being mixed before magnetic field, be opposite the reaction means of magnetic field, their cent is paramagnetic, diamagnetism or ferromagnetism data group. Besides, still have non-magnetic material, they have weak magnetism.

The tool that shows magnetism performance is magnetic hysteresis curve. It expresses the concern of B of magnetic flux density and H of magnetic field intensity.

Graph 1.  Lag curve give typical examples. The picture is offerred by NDT resource center

The side that magnetic material is showing is, although we move,remove the force that brings to bear on, they still hold magnetization position (namely, they are shown maintain a gender) . Next, return initiative dot to make material is returned, need brings to bear on intensity of negative magnetic field (H) makes its degauss (Jiao Wan force) .

Because the characteristic of magnetic material reachs its wide application, the ability that measures its performance with favorable resolution brought the revolution of physics and material domain.

Gao Lingmin spends an electron to measure

Like a lot of other sensor, magnetic sensor is accompanying system of a group of electrons, so that process small report signal,make small controller, processor or mankind’s readable input. The design of these systems and compose are built is a challenge, because be below most circumstance, signal is very small and very sensitive to noise. Accordingly, design personnel needs to acquire a balance between capacity of circuit complexity, sensor and cost.

A few often is use and relatively simple component, for example filter or amplifier, but also have other more complex package, for example modulation demodulation catenary or lock decide amplifier.

As the progress of miniaturization, recuperate circuit via often can discovering partial imitate the integrated circuit in signal catenary (the implementation inside IC) , because be compared with schism solution photograph, it makes mistake more not easily and more compact.

Graph 2.  Suddenly Er sensor the interior spare parts of IC. The picture is offerred by Allegro

On the other hand, the flexibility of compositive solution may be inferior. When the job in specific or original application, design personnel may prefer schism type options, the adjustment with need because they are likely new development catenary.

Magnetometer application

Magnetometer is used extensively in daily application. Normally, complex sensor is withheld for the lab that changes highly, for example material physics of Sitelasibao and chemistry. This kind of magnetometer can include oscillatory example magnetometer, SQUID magnetometer and AGFM (replace gradient field magnetometer) etc.

Sensor of suddenly Er effect is used extensively at application of strong magnetic field. Their application is electric machinery the motion in drive application detects and control.

Graph 3.  Suddenly Er sensor IC. The picture is offerred by Microchip

Connect regular meeting to place a few sensor, it is normally two or 3, distributing on the space it is all round electric machinery axis, spark the metallic component of sensor is located in before them. Every time before sensor of metallic component course when, they can generate square wave or sine signal, use at computational speed or position.

MEMS magnetometer is found very easily also in the market. They are inertial motion unit normally (the one part of IMU) , use at measuring acceleration, angular velocity and magnetic field. The model such as the ECompasses of STMicroelectronics is OK and compositive in PCB, receive the other part such as filter or small controller repeatedly next. The motion that you may discover to these magnetometer are used in smartphone screen detects wait for application, can show the information of screen according to its level or perpendicular direction self-correcting.

Avoid duty statement: The article is reprint an article, reprint this article purpose to depend on passing more information, the person that copyright puts in original work ‘s charge is all. If involve work copyright issue,article place uses video, picture, written language, contact please small make up undertake handling.