SENSOR MAGNETS
Precise sensor magnets
Sensor magnets are compact, highly sensitive, durable, and capable of withstanding harsh environments while delivering reliable performance. They are widely used in the automotive, robotics, and electronics industries and can be easily integrated into various systems.
Sensor Magnet Working Principle
The core of the magnetic sensor is a combination of magnetoresistive elements with a biased magnetic field, which is generally developed to sense and measure external magnetic field changes. Changes in the magnetic field are reflected as subtler changes in the resistance of magnetoresistive elements. These are readable by the sensor chip and could easily be converted into electrical signals, enabling precise measurement of magnetic field strength, direction, and variation.
Four types of magnetic sensors
According to technology, the global magnetic sensor market is divided into four main categories: Hall Effect sensors, AMR sensors, GMR sensors, and TMR sensors. Hall Effect sensors were the earliest type of magnetic sensors to be developed. With the growing demand for high precision, shares of AMR, GMR, and TMR sensors are gradually gaining momentum in the market.
- Linear Hall Effect Sensors: These sensors consist of a Hall element, linear amplifier, and emitter follower. The output signal is analogue. The magnetic field of measurement is large, and the sensor can detect the polarity of magnetism. Typical applications include electric locomotives, subways, trolleybuses, railways, and current and displacement measurements.
- Switching Hall Effect Sensors: These include a voltage regulator, Hall element, differential amplifier, Schmitt trigger, and output stage and provide digital signals as output. They are used to sense the presence or absence of a magnetic field. The most common applications are speed sensors in ABS systems, automotive speedometers and odometers, locomotive automatic door switches, car ignition systems, access control, and security alarm systems.
- Magnetometers: These sensors use the Hall effect to generate a potential difference that measures the magnitude and polarity of an external magnetic field. They are widely used in smartphones, tablets, and navigation devices and can also be employed in geophysical exploration, aerospace, and high-precision measurement systems.
GMR sensor: This sensor offers super-high sensitivity and is made from multilayer films, granular films, nanoparticle alloy films, and many other types of materials. It is widely used in consumer electronics, industries, defence, military, and medical biology. Most importantly, the GMR sensor plays a very important role in hard disk drives and magnetic storage devices.
TMR Sensors: These sensors use the tunnel magnetoresistance effect to detect magnetic fields and offer even higher sensitivity than GMR sensors. They find broad applications in hard disk heads and hold high potential for high-precision magnetic sensing, sensor arrays, and biomedical applications.
Sensor Magnet Features & Characteristics
- What are sensor magnets? Sensor magnets detect changes in magnetic fields and are used in various sensors to measure field strength and direction.
- How do sensor magnets work? They generate a magnetic field interacting with sensor components, converting field changes into electrical signals for measurement.
- Where are sensor magnets used? They are used in automotive, consumer electronics, industrial automation, medical devices, and aerospace applications.
- What are the benefits of sensor magnets? They offer high precision, durability, compact size, and low power consumption.
- Can sensor magnets be customized? Yes, sensor magnets can be tailored in size, strength, and materials for specific needs.
- How do I choose the right sensor magnet? Consider factors like magnetic field strength, size, environmental conditions, accuracy, and power consumption.
- Can sensor magnets operate in extreme conditions? Many sensor magnets are designed for harsh environments, including extreme temperatures and moisture.
- Can sensor magnets enable contactless sensing? They can detect magnetic fields without direct contact, making them ideal for proximity and position sensing.
- How long do sensor magnets last? With proper handling, sensor magnets last for many years, though factors like temperature and impact can affect performance.
Magnetic Field Distribution
The magnetic field distribution on the surface of the sensor magnet assumes typical dipole characteristics, whereby conventionally, the magnetic field emerges from the north pole and returns to the south pole after crossing the space. The magnetic field is strongest at the surface of the magnet, especially around the poles. There might be some non-uniformity in the field distribution, depending on the shape and material of the magnet. In particular, for permanent magnets, the distribution of the magnetic field on the surface is closely related to the magnet’s geometry.
