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Method for detecting velocity or displacement of an object over a surface by analyzing images of the surface

  • US 6,697,501 B2
  • Filed: 11/30/2000
  • Issued: 02/24/2004
  • Est. Priority Date: 11/30/2000
  • Status: Expired due to Term
First Claim
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1. A method for detecting relative displacement between an object and an illuminated surface comprising:

  • providing an array of detecting elements each arranged to receive light from a portion of a field of view and to provide an output responsive thereto;

    locating the array adjacent the surface during said displacement such that the field of view is moved across the surface by the displacement;

    repeatedly acquiring the output signals of the detecting elements to generate a plurality of sequential signals each corresponding to a respective image of the surface with each successive image being displaced from the previous image by a distance proportional to an amount of said displacement;

    selecting one of the sequential signals as a reference signal;

    processing the sequential signals to effect a comparison of said reference signal with at least two subsequent sequential signals to generate for each subsequent sequential signal a value indicative of displacement between the image corresponding to the reference signal and the subsequent images corresponding to said at least two subsequent sequential signals;

    and analyzing the values to determine a final value indicative of the displacement.

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