This section provides overview, applications, and principles of magnetic field sensors. Also, please take a look at the list of 1 magnetic field sensor manufacturers and their company rankings.
A magnetic field sensor is a sensor that detects the earth's magnetism (geomagnetism). It is also sometimes called an electronic compass.
There are two types of magnetic field sensors: a 2-axis type that can detect the XY axis and a 3-axis type that can detect the XYZ axis. The 2-axis type can be used on level ground, but only the 3-axis type can accurately detect the geomagnetic field when used on sloping ground.
Magnetic field sensors are generally used to detect direction. They are used as electronic compasses in GPS devices for mountain climbing and are also used in smartphones and car navigation systems to measure the orientation of the device on a map. The 2-axis type is used in automobiles to detect the XY axis, while the 3-axis type, which can detect the XYZ axis, should be used in aircraft and other vehicles capable of three-dimensional motion such as pitch and yaw.
There are three types of magnetic field sensors. Hall sensors, MR (Magneto Resistance), and MI (Magneto Impedance) are typical magnetic field sensors. The features of each type of sensor are listed below.
The magnetic flux, which is the perpendicular component of the magnetic field, gives an electromotive force to the Hall element, which senses it as geomagnetism. The Hall effect is used to measure the magnetic flux density, and after passing through an amplification circuit, the sensor outputs a voltage proportional to the magnetic flux density. They are characterized by their ease of use and are mainly used for non-contact switch applications, such as detecting the opening and closing of doors, notebook PCs, and other objects.
In MR sensors, the magnetic flux, which is the horizontal component of the magnetic field, ohms the MR element, which is then sensed as geomagnetism. The MR sensor differs from a Hall sensor in that it measures the magnitude of the geomagnetic field by utilizing the change in the electrical resistance of the MR element caused by the magnetic field.
Because of its higher sensitivity and lower power consumption compared to Hall sensors, it is used more frequently and is often used for geomagnetic sensing applications such as electronic compasses, as well as for motor rotation and position sensing applications.
MI sensors use wires made of a special material called amorphous wire, which does not have a crystalline state. When a pulse current is applied to the amorphous wire in the presence of a geomagnetic field, the MI effect is generated, and the geomagnetic field is detected using the change in magnetic impedance. The sensitivity is more than 10,000 times higher than that of a Hall sensor, so even minute changes in the geomagnetic field can be measured with high precision.
The sensor can also be used for applications that take advantage of its high sensitivity, such as direction detection (electronic compass) with ultra-low current consumption, indoor positioning, and detecting metallic foreign objects.
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