Method And Apparatus For Determining A Stray Magnetic Field In The Vicinity Of A Sensor

摘要

An apparatus (10) for determining a stray magnetic field in the vicinity of a sensor is described. The apparatus (10) has a multipole permanent magnet (60) with four or more poles and an axis of rotation (70). The multipole permanent magnet (60) produces a magnetic field (65) with magnetic field vectors (67). Two vertical Hall sensors (40a and 40) are so arranged in two positions on a circular path (50) about the axis of rotation, such that the sum of the magnet field vectors (67) measured at the two positions is substantially zero.