ENCODER FOR DETECTING BATTERYLESS ABSOLUTE POSITION

摘要

Provided is an encoder for detecting a batteryless absolute position capable of judging the accuracy of absolute position information outputted from the encoder for detecting the batteryless absolute position at power-on and outputting an alarm signal when there is a problem. The encoder is provided with an absolute position calculation unit (6), an absolute position storage unit (7) and a judgment unit (8). The absolute position calculation unit (6) calculates an absolute position including the number of rotations of a rotating shaft to be detected on the basis of detection signals outputted from four reluctance resolvers (RS0-RS3). The absolute position storage unit (7) is provided with a nonvolatile memory for storing an absolute position at power-down which is outputted from the absolute position calculation unit (6) at power-down. The judgment unit (8) compares the absolute position which is outputted from the absolute position calculation unit (6) at power-on and the absolute position at power-down stored in the nonvolatile memory, and outputs the alarm signal when the difference therebetween is larger than a predetermined value.