Patent ID: 9157770
Filing Date: 2015-10-13
Classification: G01D

Abstract:
1. An encoder for computing an intra-rotation position of a rotating body, the encoder comprising: a plurality of position-detection-signal generation systems for generating position detection signals related to the rotating body having different cycles, respectively, the position-detection signal generation systems including a position-detection-signal generation system that generates a position detection signal having one cycle with respect to one rotation of the rotating body; a first computing unit for calculating a first intra-rotation position based on the position detection signals generated by the position-detection-signal generation systems, respectively; a second computing unit for calculating a second intra-rotation position based on position detection signals generated by some of the plurality of the position-detection-signal generation systems and fewer than in the first computing unit; and a failure determination unit for determining whether its own encoder is defective based on a comparison between the first intra-rotation position and the second intra-rotation position, wherein the second computing unit calculates the second intra-rotation position based on the position detection signal generated by the position-detection-signal generation system that generates the position-detection signal having one cycle with respect to one rotation of the rotating body.