GMR / Multiturn

In many applications, it is necessary to measure angles greater than 360°. While there is a wide range of revolution counters that can be used in conjunction with a 360° sensor, However, the operating principles commonly used to date have characteristics that can sometimes have a negative impact: They either require a continuous power supply, rely on mechanical and therefore wear-prone components such as gears, or are Application range complex for the Application range and thus cost-intensive.

These problems can be solved by an innovative, patented operating principle that utilizes the Giant Magnetoresistance (GMR) effect. With this technology, revolutions are detected and stored without the need for power, using a micromagnetic basis. The effect causes the electrical resistance of a GMR sensor’s layered structure to depend on the relative orientation of the magnetization of the individual layers. Thus, the GMR effect opens up exciting possibilities for multiturn angle sensors. A magnet is attached to the sensor’s rotating shaft; as it rotates, it alters the magnetization within the structure of a specially designed GMR sensor element. Each magnetization state is evaluated resistively and assigned to a unique rotational position using a suitable algorithm. Combined with a 360° measuring sensor, this allows the absolute angular position to be measured over multiple revolutions.