Photoelectric length measurement system - performs interpolation and derives control signals for interpolation by reference comparison (OE15.1.77)

摘要

A method for measuring length involves photoelectric scanning of an incremental scale to generate two antiphase approx. sinusoidal signals (a, c) of wavelength corresponding to the scale divisions. A number of reference signals equally spaced in phase are derived from the scale divisions, and from these digital control signals for counters and display units are derived. During the time of operation of each digital control signal the instantaneous absolute magnitude of an associated measuring signal as compared with a selected reference signal is used to control a supplementary interpolation indicator.