Patent ID: 6424147
Filing Date: 2002-07-23
Classification: B62D,G01D

Abstract:
A rotation angle detection apparatus comprising:a rotor connected to a rotating body; a rotation angle detection unit for generating a first angle detection signal and a second angle detection signal of the sine waveform having a constant maximum amplitude and a same period and having approximately 1/4 wavelength phase difference concomitantly with a rotation of the rotor; a memory unit for storing the first angle detection signal and the second angle detection signal; and a control unit, wherein the control unit continuously detects amplitude absolute values of the first angle detection signal and the second angle detection signal, compares the detected amplitude absolute value of the first angle detection signal and amplitude absolute value of the second angle detection signal to determine if the amplitude absolute value of the first angle detection signal or the amplitude absolute value of the second angle detection signal is a smaller amplitude absolute value or a larger amplitude absolute value, determines an arctangent angle of a quotient value obtained by dividing the smaller amplitude absolute value by the larger amplitude absolute value to calculate the basic rotation angle of the rotating body, sets a plurality of angle processing cases based on the amplitude value of the first angle detection signal and/or the amplitude value of the second angle detection signal that have been calculated, and converts a detected basic rotation angle to a different angle value according to a predetermined conversion equation for each of the plurality of angle processing cases that have been set as described hereinabove, and the rotation angle of the rotating body is thereby detected.