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Capacitive linear encoder

  • US 10,132,653 B2
  • Filed: 12/03/2015
  • Issued: 11/20/2018
  • Est. Priority Date: 12/04/2014
  • Status: Active Grant
First Claim
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1. A capacitive linear encoder for determining positions along a feed direction comprising:

  • a read head having a multiplicity of first coupling electrodes arranged along the feed direction,a scale having a multiplicity of second coupling electrodes arranged along the feed direction, anda control and evaluation unit, wherein;

    read head and scale are displaceable relative to one another in the feed direction,the width of the first coupling electrodes and the width of the second coupling electrodes are coordinated with one another,the first coupling electrodes have at least three coupling signal phases offset with respect to one another, wherein the sequence of the coupling signal phases is defined by a phase permutation, such that in each case a series of adjacent first coupling electrodes form a P-interval,upon control by the control and evaluation unit temporally changing coupling signals are exchanged by capacitive coupling between the first and second coupling electrodes,the positions are determinable by the control and evaluation unit by a signal evaluation of the coupling signals exchanged between the first and second coupling electrodes, wherein the second coupling electrodes are divided into at least two mutually reciprocal types for a differential evaluation of the coupling signals, andthe scaleis passive, for which purpose the linear encoder comprises capacitive, signal transfer means for transferring the coupling signals between scale and read head, andhas at least one position reference marker which is formed by means of the signal transfer means, for which purpose signal transfer means are modified at a location of the scale that defines a position reference,for position reference marker identification the position reference marker is identifiable by means of identification signals controlled by the control and evaluation unit.

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