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Digital imaging-based bar code symbol reading system employing a multi-mode illumination subsystem with far-field and near field led-based illumination arrays

  • US 7,320,431 B2
  • Filed: 07/28/2004
  • Issued: 01/22/2008
  • Est. Priority Date: 11/13/2003
  • Status: Expired due to Term
First Claim
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1. A digital imaging-based bar code symbol reading system having a working range, and comprising:

  • an image formation and detection subsystem having image formation optics for producing a field of view (FOV) upon an object to be imaged and an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image-capture mode in which substantially all rows of said area-type image sensing array are enabled;

    a multi-mode LED-based illumination subsystem for automatically producing (i) narrow-band illumination within a near-portion of said FOV from a first LED illumination array in response to the generation of a first control activation signal during said image-capture mode, and (ii) narrow-band illumination within a far-portion of said FOV from a second LED illumination array in response to the generation of a second control activation signal during said image-capture mode;

    an automatic object presence and range detection subsystem for automatically producing an object detection field that spatially overlaps said FOV along a substantial portion of said working range, and automatically detecting the presence of the object within the near-portion of said FOV and generating said first control activation signal in response thereto, and automatically detecting the presence of said object within the far-portion of said FOV and generating said second control activation signal in response thereto;

    an automatic light exposure measurement and illumination control subsystem for automatically measuring the light exposure incident upon a central portion of said FOV, and controlling the operation of said first and second LED illumination arrays, so as to control the amount of narrow-band illumination delivered to said area-type image sensing array during object illumination and imaging operations;

    an image capturing and buffering subsystem for capturing and buffering a digital image detected by said image formation and detection subsystem;

    an image-processing based bar code symbol reading subsystem for processing said digital image captured and buffered by said image capturing and buffering subsystem, and reading 1D and 2D bar code symbols graphically represented therein;

    an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device;

    a system control subsystem for controlling and coordinating the operation of said subsystems; and

    a housing for containing said subsystems, and having a light transmission panel with an imaging window through which said FOV extends, said narrow-band illumination is projected, and narrow-band illumination reflected and scattered off said object is re-transmitted to said area-type image sensing array.

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