Patent ID: 8836324

Claim:
An arrangement for scanning a linear or circular measuring rod made of ferromagnetic material having a tooth-shaped structured surface comprising: at least one magnetic field sensor provided on a carrier and at least one permanent magnet, wherein said measuring rod includes one, or a plurality of, parallel teeth structures periodic in the direction of motion, said magnetic field sensor comprises sensor elements on element faces spaced in the direction of motion on a sensor face of said carrier, wherein distances of center lines of the element faces are quarters of the period length of the tooth structure to be scanned, or pluralities thereof, a magnetic axis of said at least one permanent magnet is provided at a right angle to the pole faces (N; S) and is arranged in parallel relative to edges of the teeth structure and at the distance of an air gap relative to the surface of the teeth, and the sensor face of said carrier is arranged above said tooth structure and in front of at least one pole face (N; S), and wherein a distance of a face-near edge of the sensor face relative the surface of the teeth structure is not more than the distance of the air gap.