Consideration of magnetization and detection on magnetic rotary encoder using finite element method

This article shows the results of a feasibility study of a high resolution magnetic rotary encoder. The magnetization and the detection processes of a magnetic rotary encoder were simulated using the finite element method. In addition, experimental considerations have been given to the numerical effect of the parameters on a magneto-resistive (MR) output by a method of double interpolation. The optimum condition of a Z phase (i.e., original point of the rotation) signal obtained for the magneto-resistive output was a magnetization gap 0 /spl mu/m and a magnetization current of 400 mA (i.e., the magnetized state for saturation of the medium). It was analytically determined that an increase in magnetization current or a detection gap reduction saturated the magneto-resistive output voltage. The magneto-resistive output obtained using FEM showed good numerical agreement with experimental results, given conditions when the magnetization current was 200 mA or less. It was an advantage therefore, in the case of the minimum MR element being used with a double interpolation method, to achieve a wider usable detection gap range.