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Data symbol reader and method including data symbol position evaluation

  • US 5,945,661 A
  • Filed: 06/03/1996
  • Issued: 08/31/1999
  • Est. Priority Date: 06/02/1995
  • Status: Expired due to Term
First Claim
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1. A data symbol reader, comprising:

  • a reading unit, said reading unit including an image sensing device and an optical system, said optical system forming an image of a two-dimensional data symbol on said image sensing device when said two-dimensional data symbol is in a symbol reading area of said data symbol reading device;

    evaluating means for evaluating if an entirety of said two-dimensional data symbol is within said symbol reading area based on the output of said image sensing device, said evaluation means evaluates if the entirety of a two-dimensional data symbol is within the symbol reading area by processing image signals received from the reading unit, storing the processed image signals in a memory, and extracting an outline of the data symbol from the image signals stored in the memory, wherein, if the extracted outline of the two-dimensional data symbol is a closed loop, the symbol is determined to be within the symbol reading area, and if the extracted outline is not a closed loop, the two-dimensional data symbol is determined to protrude from the symbol reading area, wherein outline extraction starts from a predetermined element of the outline of the two dimensional data symbol, detects adjacent elements of the outline in a first predetermined direction, and determines that a closed loop outline of the data symbol has been detected when repeated detection of adjacent elements in the predetermined direction results in detection of said predetermined element;

    recognizing means for recognizing a direction in which said two-dimensional data symbol protrudes from said symbol reading area, when said two-dimensional data symbol protrudes outside said symbol reading area;

    a control system, said control system comprising said evaluating means and said recognizing means;

    an indicator, responsive to said evaluating means, for indicating whether the entirety of said two-dimensional data symbol is within said symbol reading area; and

    wherein a direction in which said two-dimensional data symbol protrudes from the symbol reading area is evaluated based on an intersection of an outline of the two-dimensional data symbol image formed on the image sensing device and an outer frame of an effective picture element area of the image sensing device.

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