Patent ID: 7346837

Claim:
A relative position and/or posture measuring system comprising: a magnetic field generator including a plurality of transmission coils arrayed orthogonal to each other for generating a magnetic field from each transmission coil; a magnetic field detector for receiving the magnetic field generated in each transmission coil as a magnetic field detection value for each transmission coil; and a computing unit for computing a distance between and relative postures of the magnetic field generator and the magnetic field detector based on the magnetic field detection value for each transmission coil received by the magnetic field detector, wherein the magnetic field generator comprises a clock generator for generating a clock signal with a 50% duty cycle; a plurality of M-sequential code generators for generating code sequences different from each other from the clock signal given by the clock generator; a plurality of spread code generators each for converting each code sequence to spread code by computing an exclusive logical sum of a code sequence generated by each M-sequential code generator and a clock signal generated by the clock generator; a plurality of integrators each for generating a waveform obtained by integrating each spread code generated by each spread code generator; and a voltage to current converter for converting a waveform generated by each integrator to a voltage waveform and providing a driving current to each transmission coil by means of voltage to current conversion, and the computing unit computes the distance between the relative postures of the magnetic field generator and the magnetic field detector based on an amplitude of a magnetic field detection value obtained by reverse spreading of the spread code corresponding to the detected magnetic field detection value for each transmission coil.