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Angle detecting apparatus and angle detecting method

  • US 8,106,649 B2
  • Filed: 07/10/2009
  • Issued: 01/31/2012
  • Est. Priority Date: 07/14/2008
  • Status: Expired due to Fees
First Claim
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1. An angle detecting apparatus comprising:

  • a rotor fixed to a rotating shaft, the rotor being such that a distance between two points where a straight line passing through a center of rotation of the rotor crosses an outer periphery of the rotor is constant;

    a first magnetic sensor and a second magnetic sensor arranged opposite each other and close to the outer periphery of the rotor, the first magnetic sensor detecting a change in a magnetic field corresponding to a change in a first distance between the outer periphery of the rotor and the first magnetic sensor which distance varies periodically in conjunction with rotation of the rotor, thereby outputting a first detection signal, the second magnetic sensor detecting a change in a magnetic field corresponding to a change in a second distance between the outer periphery of the rotor and the second magnetic sensor which distance varies complementarily in conjunction with the variation in the first distance, thereby outputting a second detection signal;

    differential operation means for performing differential operation on the first detection signal and the second detection signal; and

    angle calculating means for calculating an angle of rotation of the rotating shaft based on a result of the differential operation by the differential operation means.

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