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Photoelectric position measuring system using gratings having specified dimensions to suppress harmonics

  • US 5,576,537 A
  • Filed: 07/07/1994
  • Issued: 11/19/1996
  • Est. Priority Date: 07/15/1993
  • Status: Expired due to Fees
First Claim
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1. A photoelectric measuring system comprising:

  • a light source having a plurality of light emitting areas which are separated from each other by non-emitting areas in the measuring direction;

    a movable scale having a periodic graduation positioned to receive light emitted from the light-emitting areas of the light source; and

    a scanning plate used to scan the scale and generate at least one position-dependent scanning signal, the scanning plate having a plurality of light sensitive areas which are separated from each other by non-sensitive areas in the measuring direction,wherein the light-emitting areas of the light source are dimensioned to suppress predetermined orders of harmonics and the light sensitive areas of the scanning plate are dimensioned to suppress predetermined additional orders of harmonics wherein if the predetermined orders suppressed by the light source are even ordered then the predetermined orders suppressed by the scanning plate are odd ordered and if the predetermined orders suppressed by the light source are odd ordered, then the predetermined orders suppressed by the scanning plate are even ordered.

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