A Hall element generally has four lead-out terminals, two of which are the input terminals of the bias current IC of the Hall element, and the other two are the output terminals of the Hall voltage. If the two output terminals form an outer loop, Hall current will be generated. Generally speaking, the setting of the bias current is usually given by an external reference voltage source; if the accuracy requirements are high, the reference voltage source is replaced by a constant current source. In order to achieve high sensitivity, Hall sensors are equipped with high-permeability permalloy on the sensor surface; this type of sensor has a large Hall potential but saturates around 0.05T and is only suitable for low-level applications. For use on a small scale.
In recent years, due to the rapid development of semiconductor technology, various types of new integrated Hall elements have emerged. Such components can be divided into two major categories. One is a linear component and the other is a switching component.
Zero-dissipation magnetic sensors, including housings, functional alloy wires, and skeletons. The outer shell is wrapped around the skeleton. The functional alloy wire is placed in the skeleton. It also includes an axial direction that can generate a preset magnetic field and the magnetic field lines are aligned with the functional alloy wire. Magnets. The magnet is fixed inside or outside the housing. Magnets are encapsulated and fixed by glue or potting material. The functional alloy wire is in a preset magnetic field and can work under the action of a single magnet without having to work under a rotating magnetic field, thus greatly expanding the workable field of the zero-power magnetic sensor, and greatly improving the reliability; and The direction of movement can be judged from the positive and negative of the output voltage, and the direction of motion can be detected.
The principle of zero-power magnetic sensor
Zero-power magnetic sensors use the Wiegand effect principle and use Weigente to create magnetic sensors with unique properties.
Wiegand effect: Wiegand is a new type of functional alloy wire 234 made of permalloy or vicat, with a diameter of 0.3 mm. After special processing, it becomes a two-layer structure consisting of a shell and an inner core. The outer shell and the inner core have different coercive forces, and the outer shell needs a magnetic field that is much higher than the inner core to change the magnetic polarity direction.
In order to generate a pulse, two magnets of equal magnitude but opposite polarity are used to form a working magnetic field. The magnet first arranges the shell and inner core of Wiegands in the same direction. In this process, first of all, the direction of the polarity of the core changes, and then the direction of the polarity of the housing changes. This action produces a one-directional voltage pulse output in the detection coil. Next, rotate the magnetic field 180 degrees. Wiegentes will go into reverse bias. At first, the polarity of the inner core changes, and the polarity of the outer shell then changes to the initial direction. This process in turn produces a voltage pulse in the opposite direction. As long as the magnet rotates continuously, the sensor can emit a pair, a positive and a negative pulse signal.
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