The Hall effect got its name thanks to the scientist E.G. Hall, who discovered it in 1879 when working with thin gold plates. The effect is the appearance of voltage when a conductive plate is placed in a magnetic field. This tension was called Hall voltage. The industrial application of this effect became possible only 75 years after the discovery, when semiconductor films with certain properties began to be produced. So there was a Hall sensor, the principle of which is based on the effect of the same name. This sensor is a device for measuring magnetic field strength. Many other devices are also created on its basis: sensors of angular and linear displacement, magnetic field, current, flow rate, etc. The Hall sensor has a number of advantages, due to which it has become widespread. Firstly, contactless operation eliminates mechanical wear. Secondly, it is easy to use at a fairly low cost. Thirdly, the device has a small size. Fourth, a change in the response frequency does not lead to a shift in the measurement moment itself. Fifth, the electrical signal of the sensor does not have a burst character, and when turned on, it immediately gains a constant value. Its other advantages: signal transmission without distortion, the non-contact nature of the signal transmission itself, an almost unlimited service life, a large frequency range, etc. However, it also has its drawbacks, the main of which are sensitivity to electromagnetic interference in the power circuit and temperature changes.
The principle of operation of the Hall sensor. The Hall sensor is a slot design with a semiconductor on one side and a permanent magnet on the other. When a current flows in a
magnetic field , a force acts on the electrons, the vector of which is perpendicular to both the current and the field. In this case, a potential difference appears on the sides of the plate. In the gap of the sensor is a screen through which the power lines are closed. It prevents the formation of potential differences on the plate. If there is no screen in the gap, then under the influence of a magnetic field, the potential difference will be removed from the semiconductor plate. When the screen (rotor blade) passes through the gap, the induction on the integrated circuit will be zero, and the voltage will appear at the output.
The Hall sensor and devices based on it are very widely used in the aviation, automotive, instrument-making and many other industries. They are produced by such well-known companies as Siemens, Micronas Intermetall, Honeywell, Melexis, Analog Device and many others.
The most common so-called key Hall sensor output
which changes the logical state if the magnetic field exceeds a certain value. These sensors are especially widely used in
brushless electric motors as rotor
position sensors (DPR). Logic Hall sensors are used in synchronization devices, ignition systems,
magnetic card readers, keys, proximity switches, etc. Integral linear sensors are widely used, which are used to measure linear or angular displacement and electric current.