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Device for and method for detecting a relative movement between two machine parts which are movable relative to one another

  • US 6,920,699 B2
  • Filed: 01/13/2004
  • Issued: 07/26/2005
  • Est. Priority Date: 01/13/2003
  • Status: Expired due to Fees
First Claim
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1. A device for detecting a relative movement between two machine parts which are movable relative to one another, comprising a plurality of marking lines adapted to be arranged on one of the machine parts one after the other in a direction of the relative movement of the machine parts, said marking lines having increment markings for detecting a distance of a relative movement of the both machine parts;

  • two sensors provided for sensing of the marking lines and adapted to be arranged on the other of the machine parts at a predetermined distance in the direction of relative movement of the machine parts, said sensors sensing said increment markings and each providing a sensing signal, said marking lines being arranged so that distances between two neighboring ones of said marking lines being smaller than said predetermined distance between said sensors; and

    an evaluating unit operative for determining an absolute position of the corresponding sensor between two successive increment markings based on a phase position of the sensing signal of the sensors, wherein a preceding one of the sensors is considered in the direction of relative movement and is configured to detect a transition signal comprised in said sensing signal and indicative of a transition from one of the marking rulers to another marking ruler, so that said evaluating unit detects a phase deviation between a sensing signal of the subsequent one of the sensors located in a region of one of the marking rulers and the sensing signal of the preceding one of the sensors located in the region of the other marking ruler, and also taking into consideration a phase correction determined on the basis of the phase deviation when the subsequent sensor is located in the region of the other marking ruler, during the detecting of the relative movement of the both machine parts.

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