Encoder interpolation circuit which corrects an interpolation angle between a received sine-wave encoder signal and a cosine-wave encoder signal

An encoder interpolation circuit comprising:

• an interpolative computation unit receiving two encoder signals of difference phases, carrying out interpolative computation for these signals and outputting interpolation angle data;
• a correction data forming unit obtaining and outputting correction data corresponding to a combination of a detected deviation of the two encoder signals from a normal waveform and the interpolation angle data outputted from said interpolative computation unit;
• and
• a corrective computation unit correcting the interpolation angle data outputted from said interpolative computation unit with the correction data outputted from said correction data forming unit and outputting corrected interpolation angle data,
• wherein said correction data forming unit is previously stored with the value of correction data for a combination of the output of said interpolative computation unit and the output of said correction data forming unit, and said correction data forming unit receives the output of the interpolative computation unit and the output of the correction data forming unit and outputs the previously stored value of the correction data corresponding to the combination of these outputs.

An encoder interpolation circuit comprising:

• an interpolative computation unit receiving two encoder signals of difference phases, carrying out interpolative computation for these signals and outputting interpolation angle data;
• a correction data forming unit obtaining and outputting correction data corresponding to a combination of a detected deviation of the two encoder signals from a normal waveform and the interpolation angle data outputted from said interpolative computation unit;
• and
• a corrective computation unit correcting the interpolation angle data outputted from said interpolative computation unit with the correction data outputted from said correction data forming unit and outputting corrected interpolation angle data,
• wherein said deviation of the two encoder signals is the ratio of the amplitude of one sine-wave encoder signal to the amplitude of the other sine-wave encoder signal.