ABSOLUTE ENCODER INCLUDING REDUNDANCY SPATIAL PHASE SIGNAL

摘要

PROBLEM TO BE SOLVED: To provide an absolute encoder that is robust against a measurement error.SOLUTION: The first scale track 102a of a scale extends along the direction of a measurement axis MA and includes four scale elements 173a-173d. Regarding its signal guiding function, a signal modulation scale pattern 170 includes a cyclic pattern element and a gradual pattern change element. The cyclic pattern element is provided by the cyclic array along the direction of the measurement axis MA of the four scale elements 173a-173d separated an equal distance by a space wavelength λ. The gradual pattern change element is provided by gradually changing the effective width dimension W(i) of scale elements 173a-173d over an absolute signal range along the first scale track 102a. Each of the cyclic pattern element and the gradual pattern change element generates a signal in a detector 164.SELECTED DRAWING: Figure 4