Patent ID: 8981282
Filing Date: 2015-03-17
Classification: G01D

Abstract:
1. A displacement detecting device comprising: a scale having a scale pattern with a certain arrangement pitch; an optical system configured to form an optical image of the scale pattern; a light-receiving element array having a plurality of light-receiving elements which is configured so as to be movable relative to the scale and which is configured to detect the image of the scale pattern and to output a light/dark signal obtained from the scale pattern image; a distortion compensation circuit configured to correct the light/dark signal which is output from the light-receiving element array by eliminating distortion caused by the optical system by changing positions of the respective light-receiving elements virtually on the basis of pieces of position information of the respective light-receiving elements and a distortion table obtained from distortion information of the optical system; and a position analyzing circuit configured to analyze a position of the scale using the corrected light/dark signal.