Arrangement for scanning a linear or circular measuring rod made of ferromagnetic material

US8836324B2 · kind B2 · utility

Assignee

• Sensitec GmbH · DE

Inventors

• Uwe Loreit · Wetzlar, DE
• Joerg Traute · Marburg, DE
• Jochen Schmitt · Ludwigshütte, DE

Key dates

• Filing date: May 20, 2008
• Grant date: Sep 16, 2014
• Expiry date: Jun 16, 2030

Classification

• Technology area (CPC G): Physics
• CPC primary: G01D5/2451
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Disclosed is an arrangement for high-resolution determination of positions on linear or circular ferromagnetic measuring rods (3) that have a teeth structure, said arrangement providing reliable results in an environment affected by magnetic interference. For this purpose, a magnetic field sensor (1) is placed at the point where the field of a permanent magnet (4) is at a maximum and is mounted across from the measuring rod (3) in such a way that the soft magnetic material of the measuring rod causes the field to strengthen further. The obtained field strength is sufficient to be able to use multilayer GMR sensors in which the resistance changes by more than 40 percent, thus allowing a high signal amplitude to be used for greater position resolution.