Patent ID: 6539329
Filing Date: 2003-03-25
Classification: B62D,G01D

Abstract:
A rotational angle detecting apparatus comprising:a rotor connected to a rotating member; a rotation detector for successively detecting, as the rotor rotates, a first detection signal and a second detection signal that are each sinusoidal and have a predetermined amplitude, the same cycle, and a phase difference of substantially a quarter wavelength; a memory for storing the first detection signal and the second detection signal; and a control unit, wherein the control unit changes a weighting of the first detection signal and the second detection signal according to an area of the rotational angle of the rotating member in detecting a fine rotational angle of the rotating member on the basis of amplitudes of the first detection signal and the second detection signal, the weighting being changed such that a weighting coefficient of a detection signal having a higher degree of linearity between the first detection signal and the second detection signal is set to be larger than a weighting coefficient of a detection signal having a lower degree of linearity, wherein a first area preceding and following a point at which one of the first detection signal and the second detection signal reaches its mid amplitude is defined, a second area of the one detection signal outside the first area is defined, and a third area of the one detection signal outside the second area is defined, and wherein the rotational angle of the rotating member is detected on the basis of the amplitude of the one detection signal when the one detection signal is present in the first area, or the amplitude is obtained by averaging the amplitude of the one detection signal and the amplitude of the other detection signal at a first ratio when the one detection signal is present in the second area, or the amplitude is obtained by averaging the amplitude of the one detection signal and the amplitude of the other detection signal at a second ratio when the one detection signal is present in the third area.