ABSOLUTE POSITION MEASURING METHOD, ABSOLUTE POSITION MEASURING APPARATUS, AND BINARY SCALE

摘要

In an absolute position measuring method prepared by the present invention, a data cell expressing one bit of an absolute position binary cord (APBC) includes a data section, a neutral section, and a clock section at a relatively fixed position. The method comprises as follows: a step where each section includes one or more segments, the data cell is subdivided by segments at regular intervals, and a binary scale composed of the APBC is provided; a step of acquiring the image of the binary scale; and a step of calculating an absolute position by processing the image. In the magnification of an optical system, the width of an image corresponding to one segment is integer times of a pixel width of a photo sensor array. [Reference numerals] (S102) Obtain binary scale intensity profile or image;(S112) Trace clock pixel;(S114) Set clock pixel index;(S122) Obtain absolute code pixel index;(S124) Determine binary sate of pixel sub-set by using the intensity of absolute code pixels corresponding to absolute code pixel index;(S126) Convert binary code of pixel sub-sets in which binary state is determined into absolute location through rockup table;(S130) Fine data pixel corresponding to the location of data section with maximum intensity in each pixel sub-set;(S142) Calculate relative phase of the data section by using pixel vales around the data pixels;(S144) Take -2� when the relative phase is over zero;(S150) Calculate absolute position by using absolute position code, absolute code pixel index and relative phase