Patent ID: 8140145

Claim:
A position detection apparatus comprising: a circuit provided inside an object to be detected, the circuit including at least one embedded coil; a first magnetic-field generating unit for generating a first magnetic field; a magnetic-field detecting unit for detecting an induced magnetic field generated at the embedded coil based on the first magnetic field; and a second magnetic-field generating unit for generating a second magnetic field having a phase substantially opposite to the phase of the first magnetic field, wherein the second magnetic-field generating unit includes a mutually-induced-magnetic-field generating coil for generating a mutually induced magnetic field based on the first magnetic field and a second magnetic-field generating coil for generating the second magnetic field, wherein the mutually-induced-magnetic-field generating coil is positioned in the vicinity of the first magnetic-field generating unit and the second magnetic-field generating coil is positioned in the vicinity of the magnetic-field detecting unit, and wherein the mutually-induced-magnetic-field generating coil and the second magnetic-field generating coil are electrically connected in series.