Patent ID: 7181857

Claim:
A geomagnetic sensor for auto-calibration of a deviation of a magnetic field, comprising: a geomagnetic detector which includes X-axis and Y-axis fluxgates orthogonal to each other and receives a drive signal to detect an electromotive force corresponding to a geomagnetism; a signal processor which converts the electromotive force output from the geomagnetic detector into X-axis and Y-axis output values and outputs the X-axis and Y-axis output values; and a drive signal generator which applies the drive signal to the geomagnetic detector, wherein each of the X-axis and Y-axis fluxgates of the geomagnetic detector comprises: cores; a solenoid type exciting coil which receives the drive signal to excite the cores; and at least two detection coils which wind around the cores in a solenoid form so as to detect the electromotive force induced by the cores and the exciting coil and which have different numbers of turns.