Subdivision technique of absolute angular encoder using array detector

To solve the contradiction between the size and resolution, a new subdivision technique based on array detector are proposed for absolute angular encoder. The proposed technique can well improve the angular resolution without changing the coded disc and is convenient for installing and adjusting. The coded disk is firstly lighted by the collimated beam and then magnified by the image lens. The magnified image of coded disc is finally received by the detector. Then the binary code is obtained by image processing and the minimum code unit is subdivided by the detector's pixels, respectively, which are both contributed to the angular position. The encoder system was set up according to the proposed coding principle and the feasibility of subdivision technique was experimentally testified. Additionally, some factors to influence the angular measurement precision were also analyzed, the result proved that the illumination and focus are two main influential factors. The angel resolution can be improved from 13 bit to 18 bit in the experiment.