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Magnetic length or angle measuring system having improved magnetic sensor arrangement

  • US 4,612,502 A
  • Filed: 04/04/1983
  • Issued: 09/16/1986
  • Est. Priority Date: 04/21/1982
  • Status: Expired due to Fees
First Claim
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1. In a magnetic measuring system for measuring the relative position of a first object with respect to a second object in a measuring direction, said system comprising means for defining a measuring division of alternating magnetically conducting and magnetically non-conducting zones, a scanning unit mounted to scan the division, and means for evaluating measuring signals to determine the position of the scanning unit with respect to the measuring division, the improvement comprising:

  • at least one magnet mounted to the scanning unit and oriented such that induction generated by the magnet in the measuring division extends only in planes perpendicular to the measuring direction and an air gap is created between the magnet and the measuring division;

    at least one magnetic field sensitive element firmly secured adjacent the magnet to scan the measuring division, each of which elements generates a position dependent output signal as a function of measured magnetic induction in the air gap; and

    means for supplying the output signals to the evaluating means;

    wherein the measuring division defines a division period t;

    wherein the at least one magnetic field sensitive element comprises first, second and third magnetic field sensitive elements;

    wherein the length of the first and third elements in the measuring direction is less than t/2;

    wherein the separation between the first and third elements is equal to (n+1/4)·

    t (n=1, 2, 3, . . . );

    wherein the length of the second element in the measuring direction is equal to n·

    t (n=1, 2, 3 . . . );

    wherein the supplying means operates to supply a first measuring signal, proportional to the difference between the signal of the first element and half the signal of the second element, and a second measuring signal, proportional to the difference between the signal of the third element and half the signal of the second element, to the evaluating means.

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