Position detecting circuit and apparatus using the same

A position detecting circuit comprising:

• a plurality of magnetic field detecting devices discretely disposed for outputting a signal corresponding to a magnetic field strength produced by an oppositely disposed magnetic field generation means;
• and
• a signal processing circuit having a plurality of input terminals electrically connected to the plurality of magnetic field detecting devices,
• wherein the signal processing circuit comprising:
• a correction parameter arithmetic section for computing correction parameters for bringing to a predetermined constant value a sum of an output from one of said magnetic field detecting devices and an output from another of said magnetic field detecting devices;
• and
• a position arithmetic section for computing and outputting a relative position between said magnetic field generation means and said magnetic field detecting devices based on an output difference between the output from said one magnetic field detecting device and the output from said another magnetic field detecting device and said correction parameters, and
• wherein the position arithmetic section comprises a first gain regulator and a second gain regulator whose gains are controlled by said correction parameters.