What's a Magnetic Sensor?
Zhejiang Innuovo Magnetics Co.,Ltd
NdFeB & SmCo , together with Ferrite magnet, they are widely used in Automotive, ,elevator, home Electronics, etc.
A magnetic sensor is a sensor that detects the magnitude of magnetism and geomagnetism generated by a magnet or current.?There are many different types of magnetic sensors.
This section explains the typical sensor types and their features.
Coiled
Coils are the simplest magnetic sensors that detect changes in magnetic flux density. As shown in Figure 1, the magnetic flux density in the coil increases as the magnet approaches the coil Δ B.
The induced EMF/induced current is then generated in the coil, which generates magnetic flux in the direction that prevents the magnetic flux density from increasing. Conversely, removing the magnet from the coil reduces the magnetic flux density in the coil, resulting in induced EMF and induced current in the coil to increase the magnetic flux density.
Reed?Switch
A reed switch is a sensor in which metal pieces (reed) extending from both the left and right sides are enclosed in a glass tube with a gap at the overlapping position of the reeds.?When a magnetic field is applied externally, these reeds are magnetized. When the reeds are magnetized, the overlapping parts attract each other and come into contact, then the switch turns on.
Hall?Elements
Hall elements are devices that utilize the Hall effect. "Hall" comes from the name of Dr. Hall, who discovered the Hall effect. It is based on the fact that the EMF occurs perpendicular to the current and the magnetic field when a magnetic field perpendicular to the current is applied to the object passing through it.
When current is applied to a thin film semiconductor, a voltage corresponding to the magnetic flux density and its direction is output through the Hall effect. Hall effect is used to detect magnetic fields.
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Hall elements can detect static magnetic fields with no change in magnetic flux, so they are used for a variety of applications, such as contactless switches used in conjunction with magnets, angle sensors, current sensors, etc. Geomagnetic sensors using Hall elements are widely used in smart phones and other fields.
Magnetoresistive Element
The reluctance element is made of a material which can change its own resistance value under the action of an applied magnetic field.
Magnetoresistance elements are divided into four types; AMR Anisotropic Magneto Resistive (AMR Anisotropic Magneto Resistive), GMR Giant Magneto Resistive (GMR Giant Magneto Resistive) and TMR Tunnel Magneto Resistive (TMR Tunnel Magneto Resistive), in addition to Semiconductor Magnetoresistor (SMR element).
Magnetic Sensor Applications
The advantages of magnetic sensing technology in robotics and plant automation are evident. Magnetic sensors are essential for motion control because of their higher reliability and precision in parts position and speed detection. This advantage also allows the machine arm and other components to move smoothly and accurately, ensuring high quality and safety in the manufacturing process.
In addition to automobiles, magnetic sensors are used extensively in household appliances such as washers and microwave ovens to detect whether a machine door is closed or open. Magnetic sensors are also used in medical devices. For example, when used in hearing aids, they detect whether the wearer is carrying a cell phone and then change to the appropriate mode to help the wearer hear the incoming call more clearly. They are also commonly used for floor detection in elevators for detecting whether handheld devices such as tablets or cell phones are on or off.
Magnetic sensors have a variety of functions, but two of them can be widely integrated into other circuits: Hall effect sensors and fluxgate sensors.
Hall-effect sensors are highly recommended and loved by manufacturers for their reliable operation in various electromagnetic environments. Common applications include oil gauges, which are mainly used to detect floats in oil tanks, as well as brushless motors to detect rotor positions and time currents. When magnetic sensors are integrated with other circuits, the manufacturing process eliminates the need for special materials or handling, helping to reduce design costs.
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