Patent ID: 8159214

Claim:
A position detecting system comprising: a magnetic field generator configured to generate a magnetic field in a three-dimensional space; a detecting body configured to be introduced into the three-dimensional space, the detecting body comprising: a resonance circuit configured to resonate with the magnetic field of the magnetic field generator to generate a resonance magnetic field, a current bypass circuit connected in parallel to the resonance circuit to form an alternative path of a current in the resonance circuit, and a resonance control circuit configured to control a current flow through the current bypass circuit to switch a resonant state and a non-resonant state of the resonance circuit; a magnetic field detector configured to detect: an environmental magnetic field to thereby generate detection data of the environmental magnetic field, the environmental magnetic field being a magnetic field in the three-dimensional space excluding the resonance magnetic field, and including at least a magnetic field of the magnetic field generator when the resonance control circuit switches the resonance circuit to the non-resonant state, and a spatial magnetic field in the three-dimensional space to thereby generate detection data of the spatial magnetic field, the spatial magnetic field including the environmental magnetic field and the resonance magnetic field when the resonance control circuit switches the resonance circuit to the resonant state; a position/direction calculating unit configured to perform position/direction calculating processing for calculating a position and a direction of the detecting body based on a detection data of the resonance magnetic field obtained by subtracting the detection data of the environmental magnetic field from the detection data of the spatial magnetic field; and a control unit configured to acquire the detection data of the environmental magnetic field to perform update processing on the detection data of the environmental magnetic field if the resonance circuit is in the non-resonant state, to acquire the detection data of the spatial magnetic field if the resonance circuit is in the resonant state, and to cause the position/direction calculating unit to execute the position/direction calculating processing using the detection data of the spatial magnetic field thus acquired and the detection data of the environmental magnetic field which is subjected to the update processing.