Hand-supportable digital imaging-based bar code symbol reading system employing a method of intelligently illuminating an object so as to generate a digital image thereof which is substantially free of noise caused by specular-type reflection

• US 7,281,661 B2
• Filed: 07/29/2004
• Issued: 10/16/2007
• 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:
  US10/902,710
• Publication Number:
  US 20050103864A1
• Time in Patent Office: 1,174 Days
• Field of Search: 235/462.22, 235/462.23, 235/462.24, 235/462.41, 235/462.42, 235/462.01, 235/462.09, 235/462.25
• US Class Current: 235/462.22
• 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 digital imaging-based bar code symbol reader comprises: an automatic object presence detection subsystem; a multi-mode area-type image formation and detection subsystem having narrow-area and wide-area image-capture modes of operation; a multi-mode LED-based illumination subsystem having independently controllable LED illumination arrays; an automatic light exposure measurement and illumination control subsystem; an image capturing and buffering subsystem; an image-processing bar code symbol reading subsystem; an input/output subsystem; and a system control subsystem for controlling the subsystems. The hand-supportable imaging-based bar code reader employs a method of intelligently illuminating objects during image capture, wherein the LED illumination arrays are independently controlled during particular moments of object illumination to generate digital images of objects which, through digital image analysis, are determined to be substantially free of noise (i.e. intense spatial intensity variations) caused by specular-type reflection of illumination off objects during illumination and imaging operations.

Claims

1. A hand-supportable digital imaging-based bar code symbol reading system comprising:

a hand-supportable housing having a front housing panel with a light transmission window formed therein;

an image formation and detection subsystem having (i) image formation optics for producing a field of view (FOV) through said light transmission window and upon an object to be imaged, and (ii) 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 the area-type image sensing array are enabled;

an LED-based illumination subsystem for automatically producing narrow-band illumination within said FOV from either (i) a first LED illumination subarray arranged on a first spatial location on said front housing panel, or (ii) a second LED illumination subarray arranged on a second spatial location on said front housing panel;

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 subarrays;

an image capturing and buffering subsystem for capturing and buffering digital images of the illuminated object during said image-capture mode;

an image-processing based bar code symbol reading subsystem for processing digital images captured and buffered by said image capturing and buffering subsystem, so as to rapidly determine the spatial-intensity of pixel data contained in said captured digital images, and also read at least one 1D or 2D bar code symbol graphically represented therein; and

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

(a) upon receipt of a control activation signal, said LED-based illumination subsystem produces a first field of narrow-band illumination within said FOV from said first LED illumination subarray, said image formation and detection subsystem forming and detecting a first digital image of the object, said image capturing and buffering subsystem capturing said first digital image, and said image-processing based bar code symbol reading subsystem analyzing the pixel data in said captured first digital image, and determining whether a specular-type reflection condition is detected in said captured first digital image;

(b) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is not detected in said captured first digital image, then said image-processing based bar code symbol reading subsystem automatically processes said first digital image so as to read at least one bar code symbol graphically represented in said captured first digital image;

(c) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is detected in said captured first digital image, then said automatic light exposure measurement and illumination control subsystem drives only said second LED illumination subarray, said image formation and detection subsystem forms and detects a second digital image, said image capturing and buffering subsystem captures said second digital image, and said image-processing based bar code symbol reading subsystem analyzes the pixel data in said captured second digital image and determines whether a specular-type reflection condition is detected in said captured second digital image;

(d) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is not detected in said captured second digital image, then said image-processing based bar code symbol reading subsystem automatically processes said second digital image so as to read at least one bar code symbol graphically represented therein; and

(e) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is detected in said captured second digital image, then said system control subsystem controls and coordinates said subsystems through steps (a), (b), (c) and (d) for at least one more cycle of operation, in effort to read at least one 1D or 2D bar code symbol graphically represented in a captured digital image, substantially free of noise caused by specular-type reflection of illumination off the object during object illumination and imaging operations.

2. The hand-supportable digital imaging-based bar code symbol reading system of claim 1, wherein said first LED illumination subarray is arranged above said light transmission window and said second LED illumination subarray is arranged below said light transmission window.

3. The hand-supportable digital imaging-based bar code symbol reading system of claim 2, wherein said first LED illumination subarray includes a plurality of LED light sources, and each said LED light source is provided with a spherical lens.

4. The hand-supportable digital imaging-based bar code symbol reading device of claim 3, wherein said second LED illumination subarray includes a plurality of LED light sources, and each said LED light source is provided with a spherical lens.

5. A method of illuminating objects without specular-type reflection, comprising the steps of:

(a) providing a hand-supportable digital imaging-based bar code symbol reading device including

a hand-supportable housing having a front housing panel with a light transmission window;

(1) an image formation and detection subsystem having (i) image formation optics for producing a field of view (FOV) through said light transmission window and upon an object to be imaged, and (ii) 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 the area-type image sensing array are enabled;

(2) an LED-based illumination subsystem for automatically producing narrow-band illumination within said FOV from either (i) a first LED illumination subarray arranged on a first spatial location on said front housing panel, or (ii) a second LED illumination subarray arranged on a second spatial location on said front housing panel;

(3) 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 subarrays,

(4) an image capturing and buffering subsystem for capturing and buffering digital images of the illuminated object during said image-capture mode;

(5) an image-processing based bar code symbol reading subsystem for processing digital images captured and buffered by said image capturing and buffering subsystem, so as to rapidly determine the spatial-intensity of pixel data contained in said captured digital images, and also read at least one 1D or 2D bar code symbol graphically represented therein; and

(6) a system control subsystem for controlling and coordinating the operation of said subsystems as follows;

(b) upon receiving a control activation signal, said LED-based illumination subsystem producing a first field of narrow-band illumination within said FOV from said first LED illumination subarray, and said image formation and detection subsystem forming and detecting a first digital image of the object, said image capturing and buffering subsystem capturing said first digital image, and said image-processing based bar code symbol reading subsystem analyzing the pixel data in said captured first digital image, and determining whether a specular-type reflection condition is detected in said captured first digital image;

(c) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is not detected in said captured first digital image, then said image-processing based bar code symbol reading subsystem automatically processes said first digital image so as to read at least one bar code symbol graphically represented in said captured first digital image;

(d) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is detected in said captured first digital image, then said automatic light exposure measurement and illumination control subsystem drives only said second LED illumination subarray, said image formation and detection subsystem forms and detects a second digital image, said image capturing and buffering subsystem captures said second digital image, and said image-processing based bar code symbol reading subsystem analyzes the pixel data in said captured second digital image data and determines whether a specular-type reflection condition is detected in said captured second digital image;

(e) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is not detected in said captured second digital image, then said image-processing based bar code symbol reading subsystem automatically processes said second digital image so as to read at least one bar code symbol graphically represented therein; and

(f) if said image-processing based bar code symbol reading subsystem determines that a specular-type reflection condition is detected in said captured second digital image, then said system control subsystem controls and coordinates said subsystems through steps (b), (c), (d) and (e) for at least one more cycle of operation, in effort to read at least one 1D or 2D bar code symbol graphically represented in a captured digital image, substantially free of noise caused by specular-type reflection of illumination off the object during object illumination and imaging operations.

6. A hand-supportable digital imaging-based code symbol reading system comprising:

a hand-supportable housing having a light transmission window formed therein;

an image formation and detection subsystem, embodied within said hand-supportable housing, and having (i) image formation optics for projecting a field of view (FOV) from an area-type image detection array, and upon an object to be imaged during object illumination and imaging operations, and (ii) said area-type image detection array detecting one or more digital images of the object in an image-capture mode during object illumination and imaging operations;

an LED-based illumination subsystem, disposed in said hand-supportable housing, for automatically producing illumination within said FOV from either (i) a first LED illumination subarray arranged at a first spatial location about said light transmission window, or (ii) a second LED illumination subarray arranged at a second spatial location about said light transmission window;

an image capturing and buffering subsystem for capturing and buffering digital images of the illuminated object during said image-capture mode;

an image processing subsystem for processing digital images captured and buffered by said image capturing and buffering subsystem, so as to rapidly determine the spatial-intensity of pixel data contained in said captured digital images, and also to read at least one or more 1D and/or 2D code symbols graphically represented in said digital images; and

a system control subsystem for controlling and/or coordinating the operation of said subsystems as follows;

(a) upon receipt of a control activation signal, said LED-based illumination subsystem produces a first field of illumination within said FOV from said first LED illumination subarray, said image formation and detection subsystem forming and detecting a first digital image of the object, said image capturing and buffering subsystem capturing and buffering said first digital image, and said image processing subsystem analyzing the pixel data in said first digital image, and determining whether a specular-type reflection condition is detected in said first digital image;

(b) if said image processing subsystem determines that a specular-type reflection condition is not detected in said first digital image, then said image processing subsystem automatically processes said first digital image so as to read one or more 1D and/or 2D code symbols graphically represented in said captured first digital image;

(c) if said image processing subsystem determines that a specular-type reflection condition is detected in said captured first digital image, then said LED-based illumination subsystem produces a second field of illumination within said FOV from said second LED illumination subarray, said image formation and detection subsystem forms and detects a second digital image, said image capturing and buffering subsystem captures said second digital image, and said image processing subsystem analyzes the pixel data in said second digital image and determines whether a specular-type reflection condition is detected in said second digital image;

(d) if said image processing subsystem determines that a specular-type reflection condition is not detected in said second digital image, then said image processing subsystem automatically processes said second digital image so as to read one or more 1D and/or 2D code symbols graphically represented in said second digital image.

7. The hand-supportable digital imaging-based code symbol reading system of claim 6, which further comprises:

(e) if said image processing subsystem determines that a specular-type reflection condition is detected in said second digital image, then said system control subsystem controls and coordinates said subsystems through steps (a), (b), (c) and (d) for at least one more cycle of operation, in effort to read one or more 1D and/or 2D code symbols graphically represented in a digital image, with a significant reduction in noise caused by specular-type reflection of illumination off the object during object illumination and imaging operations.

8. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein said first LED illumination subarray is arranged above said light transmission window and said second LED illumination subarray is arranged below said light transmission window.

9. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein said first LED illumination subarray includes a plurality of LED light sources, and each said LED light source is provided with a spherical lens.

10. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein said second LED illumination subarray includes a plurality of LED light sources, and each said LED light source is provided with a spherical lens.

11. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein said illumination is narrow-band illumination.

12. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein said illumination is visible illumination.

13. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein each said code symbol is a bar code symbol selected from the group consisting of a 1D bar code symbol, a 2D bar code symbol, and a data matrix type code symbol structure.

14. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein said control activation signal is generated by an automatic object detection subsystem disposed within said hand-supportable housing.

15. The hand-supportable digital imaging-based code symbol reading system of claim 6, wherein said control activation signal is generated by a manually-actuated trigger switch integrated with said hand-supportable housing.

16. A method of illuminating and imaging objects while reducing the effects of specular-type reflection, said comprising the steps of:

(a) providing a hand-supportable digital imaging-based code symbol reading device including

(1) a hand-supportable housing having an imaging window;

(2) an image formation and detection subsystem, embodied within said engine housing, and having (i) image formation optics for projecting a field of view (FOV) from an area-type image detection array, through said imaging window and upon an object to be imaged during object illumination and imaging operations, and (ii) said area-type image detection array detecting one or more digital images of the object during object illumination and imaging operations;

(2) an LED-based illumination subsystem for automatically producing illumination within said FOV from either (i) a first LED illumination subarray arranged at a first spatial location about said imaging window, or (ii) a second LED illumination subarray arranged at a second spatial location about said imaging window;

(3) an image capturing and buffering subsystem for capturing and buffering digital images of the illuminated object during said object illumination and imaging operations;

(5) an image processing subsystem for processing digital images captured and buffered by said image capturing and buffering subsystem, so as to rapidly determine the spatial-intensity of pixel data contained in said captured digital images, and also read one or more 1D and/or 2D code symbols graphically represented therein; and

(6) a system control subsystem for controlling and/or coordinating the operation of said subsystems as follows;

(1) upon receipt of a control activation signal, said LED-based illumination subsystem produces a first field of illumination within said FOV from said first LED illumination subarray, said image formation and detection subsystem forming and detecting a first digital image of the object, said image capturing and buffering subsystem capturing and buffering said first digital image, and said image processing subsystem analyzing the pixel data in said first digital image, and determining whether a specular-type reflection condition is detected in said first digital image;

(2) if said image processing subsystem determines that a specular-type reflection condition is not detected in said first digital image, then said image processing subsystem automatically processes said first digital image so as to read one or more 1D and/or 2D code symbols graphically represented in said captured first digital image;

(3) if said image processing subsystem determines that a specular-type reflection condition is detected in said captured first digital image, then said LED-based illumination subsystem produces a second field of illumination within said FOV from said second LED illumination subarray, said image formation and detection subsystem forms and detects a second digital image, said image capturing and buffering subsystem captures said second digital image, and said image processing subsystem analyzes the pixel data in said second digital image and determines whether a specular-type reflection condition is detected in said second digital image;

(4) if said image processing subsystem determines that a specular-type reflection condition is not detected in said second digital image, then said image processing subsystem automatically processes said second digital image so as to read one or more 1D and/or 2D code symbols graphically represented in said second digital image.

17. The method of claim 16, which further comprises:

(e) if said image processing subsystem determines that a specular-type reflection condition is detected in said second digital image, then said system control subsystem controls and coordinates said subsystems through steps 6(1), 6(2), 6(3) and 6(4) for at least one more cycle of operation, in effort to read one or more 1D and/o 2D code symbol graphically represented in a digital image, with a significant reduction in noise caused by specular-type reflection of illumination off the object during object illumination and imaging operations.

18. The method of claim 16, wherein said first LED illumination subarray is arranged above said light transmission window and said second LED illumination subarray is arranged below said light transmission window.

19. The method of claim 16, wherein said first LED illumination subarray includes a plurality of LED light sources, and each said LED light source is provided with a spherical lens.

20. The method of claim 16, wherein said second LED illumination subarray includes a plurality of LED light sources, and each said LED light source is provided with a spherical lens.

21. The method of claim 16, wherein said illumination is narrow-band illumination.

22. The method of claim 21, wherein said narrow-band illumination is visible illumination.

23. The method of claim 16, wherein each said code symbol is a bar code symbol selected from the group consisting of a 1D bar code symbol, a 2D bar code symbol, and a data matrix type code symbol structure.

24. The method of claim 16, wherein said control activation signal is generated by an automatic object detection subsystem disposed within said hand-supportable housing.

25. The method of claim 16, wherein said control activation signal is generated by a manually-actuated trigger switch integrated with said hand-supportable housing.