| 摘要 |
PURPOSE: To perform highly accurate detection by finding a ratio of a plurality of sine waveforms having specific angle dislocations, obtaining a triangular waveform which linearly changes for the change of the position of a moving member, and interpolating the position of the moving member on the basis of a composed triangular wave. CONSTITUTION: Signals A1, B1 which A/D-convert two analog signals Va, Vb mutually having the dislocation of a 90 deg. phase are prepared from an MR element output amplification part 8. In a control part 11, an A/D conversion value of each analog signal is converted into a difference from the intermediate level, ratios of signals themselves is calculated, and K1 and K2 are obtained. A triangular wave of a large amplitude is obtained by connecting K1 and K2 at the intersection thereof in the control part 11, and interpolation calculation is performed. In the interpolation calculation, the values of K1 are divided into four cases, and a minute distanceΔd between pulses is calculated. And a final moved distance D is calculated by an approximately moved distance d and the minute moved distanceΔd.
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