MULTI-TURN ABSOLUTE ENCODER, METHOD FOR DETECTING ROTATION NUMBER BY MULTI-TURN ABSOLUTE ENCODER, AND COMPUTER RECORDING MEDIUM RECORDING SAME

摘要

The present invention provides a multi-turn absolute encoder and a method for detecting the rotation number by a multi-turn absolute encoder. A multi-turn absolute encoder according to the present invention comprises: a gear comprising a main shaft and at least sub-shaft having teeth meshing with teeth of the main shaft; at least one magnetic sensor for sensing a change in magnetic force from at least one bipolar magnet provided on each of the main shaft and the at least one sub-shaft; a database storing a lookup table displaying the relation between the rotation number of the main shaft and the rotation number of the at least one sub-shaft as an index within the range of the least common multiple of the number of teeth of the main shaft and the number of teeth of the at least one sub-shaft; an angle detection portion for calculating the absolute angle of each shaft as a triangle wave using the change in magnetic force sensed by the least one magnetic sensor as each shaft rotates; a sub-shaft rotation number detection portion for detecting the rotation number of the at least one sub-shaft using the change in magnetic force sensed by the at least one magnetic sensor; and a main shaft rotation number calculation portion for detecting the absolute angle of each shaft at a specific timepoint from the triangle wave, for detecting the relative rotation number of the main shaft from the relation with each sub-shaft using the absolute angle of each shaft at a specific timepoint and the number of teeth of each shaft, and for detecting the absolute rotation number of the main shaft from the lookup table using the detected relative rotation number of the main shaft as an index. According to the present invention, the relative rotation angle of the main shaft is calculated in a stepwise manner, thereby facilitating acquisition of the relative rotation number of the main shaft, such that the index of the lookup table and the absolute rotation number of the main shaft can be easily calculated.