Patent ID: 7128266
Filing Date: 2006-10-31
Classification: G06K

Abstract:
1. A hand-supportable digital imaging-based bar code symbol reading device supporting narrow-area and wide-area modes of illumination and image capture, said hand-supportable digital imaging-based bar code symbol reading device comprising: a hand-supportable housing having a light transmission aperture; a multi-mode image formation and detection subsystem, disposed in said hand-supportable housing, and 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 either (i) a narrow-area image capture mode in which a few central rows of pixels on said area-type image sensing array are enabled, or (ii) a wide-area image capture mode in which substantially all rows of said area-type image sensing array are enabled; a multi-mode LED-based illumination subsystem, disposed in said hand-supportable housing, including (i) a first LED-based illumination array for producing a narrow-area field of narrow-band visible illumination within the FOV of said multi-mode image formation and detection subsystem during said narrow-area image capture mode, and (ii) a second LED-based illumination array for producing a widearea field of narrow-band visible illumination within the FOV of said multi-mode image formation and detection subsystem during said wide-area image capture mode; an automatic light exposure measurement and illumination control subsystem, disposed in said hand-supportable housing, for supporting the following operations, (i) automatically driving the first LED-based illumination array when said system is operated in said narrow-area image capture mode, and the second LED-based illumination array when said device is operated in said wide-area image capture mode, so that objects within the FOV of said device are illuminated with said narrow-band visible illumination, (ii) automatically measuring the light exposure incident upon a central portion of said FOV using a photo-detector independent and separate from said area-type image sensing array, and (iii) automatically controlling said first and second LED-based illumination arrays so that objects within the FOV of said device are exposed to narrow-band visible illumination having an intensity and a duration sufficient for the formation and detection of high quality digital images at said area-type image sensing array; an image capturing and buffering subsystem, disposed in said hand-supportable housing, for capturing and buffering 2-D images detected by said multi-mode image formation and detection subsystem; a narrow-band optical filter subsystem realized by a high-pass filter element mounted at said light transmission aperture, and a low-pass filter element mounted either before said image sensing array or anywhere after said light transmission aperture, and permitting only said narrow-band visible illumination to be transmitted to said area-type image scnsing array, whereas all other components of ambient light collected by said image formation optics are substantially rejected prior to incidence at said area-type image sensing array; an image-processing based bar code symbol reading subsystem, disposed in said hand-supportable housing, for processing images captured and buffered by said image capturing and buffering subsystem and reading 1-D and 2-D bar code symbols represented in said processed images; an input/output subsystem, disposed in said hand-supportable housing, for outputting processed image data to an external host system or other information receiving or responding device; and a control subsystem, disposed in said hand-supportable housing, for controlling and coordinating said subsystems.