Device for the contactless detection of the speed and / or position of a sensor part with an encoder

Device for the contactless detection of the rotational speed and / or position of a rotatable about an axis of the sensor part with a permanent magnet encoder in a ring shape with alternately arranged in the circumferential direction of North and South poles and at least two different pole widths as well as with a sensing head with a difference-Hall sensor, the encoder and double track encoder (1) is formed with opposite magnetization and that a respective sensor element (9, 10) of the differential Hall sensor (8) of the encoder tracks (4, 5) is assigned.