Patent ID: 7177779

Claim:
An azimuth measuring device comprising: earth magnetism detection means with 2 or 3 axes for detecting earth magnetism; output data acquisition means for acquiring 2-axis output data when the orientation of said earth magnetism detection means changes while keeping the detection directions of said two axes on a predetermined plane or 3-axis output data when the orientation of said earth magnetism detection means changes in a three-dimensional space repeatedly a predetermined number of times or more; reference point estimation means for defining a reference point on a two-dimensional coordinate system whose coordinate values correspond to said 2-axis output data or on a three-dimensional coordinate system whose coordinate values correspond to said 3-axis output data and estimating the coordinates of reference point using a statistical technique so that a variation in the distance from the 2-axis or 3-axis output data group acquired by said output data acquisition means to the reference point becomes a minimum; and offset information calculation means for calculating offset information with respect to the output data of said earth magnetism detection means based on said coordinates of reference point.