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Compact magnetic encoder

  • US 4,983,916 A
  • Filed: 01/25/1989
  • Issued: 01/08/1991
  • Est. Priority Date: 01/26/1988
  • Status: Expired due to Fees
First Claim
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1. An improved magnetic encoder, comprising:

  • a housing having an axial through-hole;

    a magnetic rotary spindle rotatably supported in said axial through-hole of said housing and provided with a magnetized pattern formed circularly on its one longitudinal end face along the periphery; and

    a magnetic sensor attached to said housing and facing said magnetized pattern on said one longitudinal end face of said rotary spindle with a prescribed clearance;

    said magnetized pattern being formed by use of a sine wave of a wavelength λ and

    having a constant pitch equal to said wavelength λ

    ;

    said magnetic sensor being made up of first and second magnetic resistor elements which (i) vary in inherent resistance depending on the intensity of an applied magnetic field and which (ii) are electrically separated from each other by an insulating layer;

    each said first magnetic resistor element being phased from an adjacent second magnetic resistor element by a distance equal to λ

    /4; and

    said first and second magnetic resistor elements being arranged in a circular disposition just corresponding to the circular arrangement of said magnetized pattern on said one longitudinal face of said rotary spindle;

    being circularly arranged side-by-side, each forming a hemicircle; and

    being concentrically arranged without superposition.

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