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Multi-resolution bar code reader

  • US 5,278,397 A
  • Filed: 07/25/1991
  • Issued: 01/11/1994
  • Est. Priority Date: 07/25/1991
  • Status: Expired due to Term
First Claim
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1. A method of increasing a range of a working angle of a wand type reader during reading of optically encoded information, wherein the working angle is defined as the angle between a major axis of the wand type reader and a line normal to a surface on which the optically encoded information appears, said method comprising the steps of:

  • (a) arranging light emitting and detecting elements in the wand to(i) optically sense light reflected from a first effective sensing spot of a first diameter, and simultaneously(ii) optically sense light reflected from a second effective sensing spot of a second diameter which is different from the first diameter;

    (b) passing the first and second effective sensing spots over the optically encoded information for simultaneously;

    (i) sensing the optically encoded information as it passes through the first effective sensing spot and in response thereto producing a sensing signal, and(ii) sensing the optically encoded information as it passes through the second effective sensing spot and in response thereto producing another sensing signal,wherein the diameters of the first and second effective sensing spots increase in proportion to increases in the working angle; and

    (c) deriving a single decoded representation of the optically encoded information from the two sensing signals , wherein for different working angles at least one of the effective sensing spots will be of appropriate size to produce a valid reading of the optically encoded information.

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