Automatic hand-supportable image-based bar code symbol reader having image-processing based bar code reading subsystem employing simple decode image processing operations applied in an outwardly-directed manner referenced from the center of a captured narrow-area digital image of an object bearing a 1D bar code symbol

• US 7,428,998 B2
• Filed: 07/27/2004
• Issued: 09/30/2008
• Est. Priority Date: 11/13/2003
• Status: Active Grant

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Knowles, C. Harry, Au, Ka Man, Liu, Yong, Liu, Liang, Schmidt, Mark, Ghosh, Sankar, Kotlarsky, Anatoly, Tao, Xi, Zhang, Wenhua, Amundsen, Thomas, Hou, Rui, Russell, Garrett, Byun, Sung, Yu, Hongpeng, Bonanno, John, Schnee, Michael, Spatafore, Pasqual
• Primary Examiner(s): Kim; Ahshik
• Application Number:
  US10/901,446
• Publication Number:
  US 20050103849A1
• Time in Patent Office: 1,526 Days
• Field of Search: 235/472.01, 235/462.01, 235/462.42, 235/462.24
• US Class Current: 235/472.01
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners

Abstract

A hand-supportable automatic digital imaging-based bar code symbol reading device comprises: an automatic object presence detection subsystem; an area-type image formation and detection subsystem having a narrow-area image-capture mode of operation; a LED-based illumination subsystem having narrow-area illumination mode of operation; an image capturing and buffering subsystem; and an image-processing bar code symbol reading subsystem. The automatic object presence detection subsystem automatically detects an object, and the LED-based illumination subsystem automatically illuminates the detected object in a field of narrow-area narrow-band illumination, while the area-type image formation and detection subsystem captures a narrow-area image thereof. The image-processing bar code symbol reading subsystem automatically and directly applies decode image processing operations on the captured image, in an outwardly-directed manner, referenced from the center of the captured narrow-area image, to automatically read a 1D bar code symbol on the detected object.

Claims

1. An automatic hand-supportable digital imaging-based bar code symbol reading device comprising:

a hand-supportable housing;

an area 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 image sensing array for detecting imaged light reflected off the object during illumination operations in a narrow-area image-capture mode in which a few central rows of pixels on said area image sensing array are enabled;

a LED-based illumination subsystem for producing a field of narrow-area narrow-band illumination within said FOV during said narrow-area image-capture mode;

an automatic object presence detection subsystem for automatically producing an object detection field within said FOV, for detecting an object having a 1D bar code symbol thereon;

an image capturing and buffering subsystem for capturing and buffering a narrow-area digital image of said detected object;

an image-processing based bar code symbol reading subsystem for automatically and directly processing said narrow-area digital image using decode image-processing based operations applied in an outwardly-directed manner on said narrow-area digital image, referenced from the center of said captured narrow-area digital image so as to attempt to read the 1D bar code symbol graphically represented within the narrow-area digital image of said object;

an input/output subsystem for outputting processed image data from said image-processing based bar code symbol reading subsystem, to an external host system or other information receiving or responding device; and

a system control subsystem for controlling and coordinating each said subsystem;

wherein said imaging-based bar code reading subsystem reads at least one 1D bar code symbol represented in said capture narrow-area digital image by processing said narrow-area digital image using a method that comprises the steps of;

(a) calculating the center pixel in said captured narrow-area digital image;

(b) starting from said calculated center point, virtually scanning said narrow-area digital image using a spot-size window of pixels, and then processing said narrow-area digital image to determine if a first border in a bar code symbol is found, and if so, storing the pixel data in an image buffer;

(c) if a first border is found during step (b), then, once again starting from said calculated center point, scanning said digital image using a spot-size window of pixels, and then processing said narrow-area digital image to determine if a second border in a bar code symbol is found, and if so, buffering the pixel data in said image buffer;

(d) if said first and second borders are found, during steps (b) and (c), then processing said captured digital image so as to read a bar code symbol within the scanned line of image data associated with captured narrow-area digital image, and after the bar code symbol is read, then terminate image processing;

(e) if a first border of a bar code symbol is not found during step (d), then determining if all possible scan lines within said captured narrow-area digital image have been processed;

(f) if all possible scan lines have been processed through said narrow-area digital image, then terminate processing;

(g) if all scan lines through said captured narrow-area image have not been processed at step (f), then advance to the next line of scan data in said captured narrow-area digital image and then scanning and processing the image data along the new scan line using a spot-size window of pixels;

(h) if the second border of a bar code symbol is not found at step (d), then determining whether all scan lines through said captured narrow-area digital image have been processed;

(i) if all scan lines through said captured narrow-area digital image have been processed, then terminate processing;

(j) if all scan lines have not been processed at this stage of processing, then advance to the next line of scan data within said captured narrow-area digital image, for processing;

(k) if a bar code symbol is not read within the current line of scan data being processed, then determine if all lines of scan data have been processed;

(l) if all lines of scan data have not been processed, then advance to the next line of scan data in said captured narrow-area digital image, and then resume scanning and processing along the new scan line using a spot-size window of pixels;

(m) if all lines of scan data have been processed, then terminate processing; and

(n) for every bar code symbol that is decoded, produce symbol character data and save the same.

2. The automatic hand-supportable digital imaging-based bar code symbol reading device of claim 1, wherein the 1D bar code symbol graphically represented in said captured narrow-area digital image contains portions which have a high likelihood of spatial location close to the center of said narrow-area digital image, and wherein said bar code symbol is oriented at about zero degrees relative to a horizontal axis passing through said narrow-area digital image.

3. The automatic hand-supportable digital imaging-based bar code symbol reading device of claim 2, wherein said image-processing based bar code symbol reading subsystem comprises:

(i) directly processing said narrow-area digital image, one line of scan data at a time, starting from the middle thereof,

(ii) examining the zero-crossings of said processed narrow-area digital image;

(iii) filtering said digital image at zero (0) degrees and 180 degrees relative to the horizontal axis, to generate bar-and-space-count data therefrom; and

(iv) decoding said bar and space patterns using conventional decoding algorithms to read said 1D bar code symbol represented in said captured narrow-area digital image.

4. The automatic hand-supportable digital imaging-based bar code symbol reading device of claim 3, wherein if a bar code symbol is not decoded in step (iv), then said imaging-based bar code reading subsystem automatically processes, at step (i) another line of scan data within said captured narrow-area digital image, starting from a pixel offset, which is computed assuming that the region of interest (ROI) has a constant maximum height equal to the pixel height of said captured narrow-area digital image.

5. The automatic hand-supportable digital imaging-based bar code symbol reading device of claim 1, which further comprises an automatic light exposure measurement and illumination control subsystem having light exposure measurement circuitry for measuring the light exposure incident upon a central portion of said FOV, and LED illumination driver circuitry for automatically controlling the operation of said LED illumination subsystem.

6. An automatic hand-supportable digital imaging-based bar code symbol reading device comprising:

a hand-supportable housing;

an area 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 image sensing array for detecting imaged light reflected off the object during illumination operations in a wide-area image-capture mode in which rows of pixels on said area image sensing array are enabled;

an automatic object presence detection subsystem for automatically producing an object detection field within said FOV, for detecting an object having a 1D bar code symbol thereon and generating a trigger signal;

a LED-based illumination subsystem having an LED illumination array for producing a field of narrow-band illumination within said FOV during said wide-area image-capture mode;

an automatic light exposure measurement and illumination control subsystem having (i) light exposure measurement circuitry for measuring the light exposure incident upon a portion of said FOV, and (ii) LED illumination driver circuitry, responsive to said light exposure measurement circuitry, for automatically controlling the operation of said LED illumination subsystem;

an image capturing and buffering subsystem for capturing and buffering a wide-area digital image of said detected object;

an image-processing based bar code symbol reading subsystem for automatically processing said wide-area digital image using decode image-processing based operations applied on said wide-area digital image so as to attempt to read the 1D bar code symbol graphically represented within the wide-area digital image of said object;

an input/output subsystem for outputting processed image data from said image-processing based bar code symbol reading subsystem, to an external host system or other information receiving or responding device; and

a system control subsystem, responsive to said trigger signal, for controlling and coordinating said subsystems.

7. The automatic hand-supportable digital imaging-based bar code symbol reading device of claim 6, wherein said LED illumination array comprises a plurality of visible light emitting diodes (LEDs).

8. The automatic hand-supportable digital imaging-based bar code symbol reading device of claim 6, wherein said area image sensing array comprises a 2D CMOS image sensing array.