초록 ▼

Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by s

Two A.C. output signals amplitude-modulated in accordance with two function values (sine and cosine) differing from each other in correspondence to a position-to-be-detected are received from a position sensor such as a resolver. By performing an addition or subtraction between a signal derived by shifting the electric phase of one of the received A.C. output signals by a predetermined angle, and the other received signal, two electric A.C. signals (sin(.omega.t .+-.d.+-..theta.), sin(.omega.t.+-.d-.theta.)) are electrically synthesized which have electric phase angles (.theta.) corresponding to the position-to-be-detected and are phase-shifted in opposite directions. ".+-.d" here represents phase variation error caused by factors, other than the position-to-be-detected, such as temperature change. In the synthesized two signals, the phase variation errors (.+-.d) appear in the same direction, while the phase differences (.theta.) corresponding to the position are shifted in opposite, positive and negative, directions. Thus, by measuring the respective phase shift amounts (.+-.d.+-..theta., .+-.d-.theta.) and performing appropriate operation, it is allowed to cancel out or extract the error (.+-.d) so that an accurate phase difference (.theta.) can be detected.

대표청구항 ▼

[ What is claimed is:] [7.] A method of detecting a position by use of an inductive position detector, said position detector being excited by a predetermined reference signal to generate a first output signal having been amplitude-modulated using, as an amplitude coefficient, a first function value

[ What is claimed is:] [7.] A method of detecting a position by use of an inductive position detector, said position detector being excited by a predetermined reference signal to generate a first output signal having been amplitude-modulated using, as an amplitude coefficient, a first function value corresponding to a position-to- be-detected and generate a second output signal having been amplitude-modulated using, as an amplitude coefficient, a second function value corresponding to the position-to-be-detected, said method comprising the steps of:receiving said first and second output signals from said position detector;forming first and second data signals by combining said received first and second output signals, said first data signal having an electric phase angle shifted in a positive direction in relation to the position-to-be-detected, said second data signal having an electric phase angle shifted in a negative direction in relation to the position-to-be-detected;measuring an electric phase difference between said predetermined reference signal and said first data signal to obtain first phase data;measuring an electric phase difference between said predetermined reference signal and said second data signal to obtain second phase data; andcalculating position detection data corresponding to the position-to-be-detected on the basis of said first and second phase data.