Automatically-triggered digital video imaging based code symbol reading system employing illumination and imaging subsystems controlled in response to real-time image quality analysis

• US 7,654,461 B2
• Filed: 06/06/2007
• Issued: 02/02/2010
• 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, Au, Ka Man, Good, Timothy, Kotlarsky, Anatoly, Hou, Richard, Veksland, Mikhail, Meagher, Mark, Hu, Daniel
• Primary Examiner(s): Kim; Ahshik
• Application Number:
  US11/810,450
• Publication Number:
  US 20080048038A1
• Time in Patent Office: 972 Days
• Field of Search: 235/462.42, 235/462.01, 235/462.09, 235/462.24, 235/462.25
• US Class Current: 235/462.42
• CPC Class Codes: G06K 7/10683 Arrangement of fixed elements
• CPC Class Codes: G06K 7/10712 Fixed beam scanning
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10801 Multidistance reading
• CPC Class Codes: G06K 7/10831 Arrangement of optical elements, e.g. lenses, mirrors, prisms optical elements per se G02B
• 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

Abstract

An automatic automatically-triggered digital video imaging based code symbol reading system for use in point of sale (POS) environments, employing an adaptive control process involving the real-time analysis of the exposure quality of captured frames of digital image data and the real-time reconfiguration of system control parameters (SCPs) based on the results of such exposure quality analysis. By virtue of the present invention, the system enables the reliable reading of code symbols graphically represented in digital images, under demanding point-of-sale lighting conditions and other challenging environments.

Claims

1. An automatically-triggered digital video imaging based code symbol reading system for reading code symbols on objects presented at point of sale (POS) environments, said automatic automatically-triggered digital video imaging based code symbol reading system comprising:

a housing having an imaging window;

a digital image formation and detection subsystem, disposed within said housing, and having 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 illuminated and imaged during object illumination and video-imaging operations, and said area-type image detection array detecting frames of digital video image data of the object during said object illumination and video-imaging operations, and wherein said digital image formation and detection subsystem is characterized by one or more system control parameters (SCPs) selected from a first group of system control parameters (SCPs);

an illumination subsystem, disposed within said housing, and having an illumination array for producing and projecting a field of illumination within said FOV during said object illumination and video-imaging operations, and wherein said illumination subsystem is characterized by one or more system control parameters selected from a second group of system control parameters (SCPs);

an automatic object detection subsystem, disposed in said housing, for automatically detecting the presence of an object in said FOV, and automatically generating a triggering signal indicative of the object present in said FOV;

an automatic illumination control subsystem, disposed within said housing, for automatically controlling said illumination array during said object illumination and video-imaging operations;

a digital video frame capturing and buffering subsystem, disposed within said housing, for capturing and buffering said frames of digital video data in memory, during said object illumination and video-imaging operations;

a digital video image processing subsystem, disposed in said housing, for processing said frames of digital video image data and (i) measuring the exposure quality of said digital images, and (ii) reading one or more 1D and/or 2D code symbols graphically represented in said frames of digital video image data, and producing symbol character data representative of said read one or more 1D and/or 2D code symbols;

an input/output subsystem, disposed in said housing, for transmitting said symbol character data to an external host system or other information receiving or responding device;

a system control subsystem for managing, in memory, said first and second sets of SCPs and also exposure quality threshold (EQTs) parameters, and controlling or coordinating the operation of said subsystems;

wherein during object illumination and imaging operations, said digital video image processing subsystem automatically processes said frames of digital image data so as to measure and analyze the exposure quality of said frames of digital image data in relation to said EQT parameters, and automatically reconfigure said first and/or second set of SCPs based on the results of said exposure quality analysis.

2. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said first group of SCPs are selected from the group consisting of (i) a shutter mode parameter, (ii) an electronic gain parameter, (iii) a programmable exposure time parameter, for each block of pixels detected in said image detection array, and (iv) an image capture mode parameter.

3. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said second group of SCPs are selected from the group consisting of:

(i) an illumination mode parameter, (ii) an automatic illumination control parameter, and (iii) an illumination field type parameter.

4. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said measured exposure quality of each said frame of digital video image data is a quantitative measure selected from the group consisting of brightness quality or level, and image saturation of said frame of digital video image data.

5. The automatically-triggered digital video imaging based code symbol reading system of claim 4, wherein if the measured exposure quality does not satisfy said EQT parameters, then new system control parameters (SCPs) are calculated and flags are set to indicate that said automatically-triggered digital video imaging based code symbol reading system should be reconfigured prior to acquiring a frame of digital video image data during the next acquisition cycle;

otherwise, the current system control parameters (SCPs) are maintained.

6. The automatically-triggered digital video imaging based code symbol reading system of claim 4, wherein when the computed exposure quality is relatively low, then said system control parameters are dynamically re-evaluated and set to the proper values.

7. The automatically-triggered digital video imaging based code symbol reading system of claim 2, wherein said image capture mode parameter includes a narrow-area image capture parameter and a wide-area image capture parameter.

8. The automatically-triggered digital video imaging based code symbol reading system of claim 3, wherein said illumination mode parameter includes off, continuous and strobe/flash values.

9. The automatically-triggered digital video imaging based code symbol reading system of claim 3, wherein said automatic illumination control parameter includes ON and OFF values.

10. The automatically-triggered digital video imaging based code symbol reading system of claim 3, wherein said illumination field type parameter includes a narrow-area near-field illumination parameter, a wide-area far-field illumination parameter, a narrow-area field of illumination parameter, and a wide-area field of illumination parameter.

11. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said automatic object detection subsystem further comprises an infrared (IR)-based object presence detection subsystem.

12. The automatically-triggered digital video imaging based code symbol reading system of claim 11, wherein said IR-based object presence detection subsystem further comprises an IR-based light emitting diode (LED) and an IR-based photo-receiving diode.

13. The automatically-triggered digital video imaging based code symbol reading system of claim 1, 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 automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said image formation optics comprises a lens barrel assembly for supporting a plurality of lenses.

15. The automatically-triggered digital video imaging based code symbol reading system of claim 1, which further comprises:

an automatic exposure measurement subsystem for measuring the intensity of illumination reflected and/or scattered ef off the illuminated object, and producing an electrical signal representative of said measured intensity; and

wherein said automatic illumination control subsystem further comprises digital circuitry for controlling drive signals provided to said illumination array, in response to said electrical signal produced by said automatic exposure measurement subsystem.

16. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said illumination subsystem comprises:

(i) an illumination board supported by having a central aperture through which said FOV passes during object illumination and imaging operations, and on which said illumination array is mounted; and

(ii) an assembly of lenses for focusing and/or shaping illumination emanating from said illumination array so as to produce said field of illumination within said FOV.

17. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said field of illumination comprises narrow-band illumination produced from said illumination array.

18. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said illumination array comprises a plurality of light emitting diodes (LEDs).

19. The automatically-triggered digital video imaging based code symbol reading system of claim 18, wherein said narrow-band illumination is visible to the human vision system.

20. The automatically-triggered digital video imaging based code symbol reading system of claim 1, which further comprises a computing platform for implementing said digital video image processing subsystem, said input/output subsystem and said system control subsystem.

21. The automatically-triggered digital video imaging based code symbol reading system of claim 20, wherein said computing platform includes (i) a multi-tier modular software architecture characterized by an Operating System (OS) layer and an Application layer, and (ii) a microprocessor for running one or more applications stored in one or more software libraries maintained in said Application layer.

22. The automatically-triggered digital video imaging based code symbol reading system of claim 21, wherein said multi-tier modular software architecture further comprises a System CORE (SCORE) layer positioned between said OS layer and said Application layer.

23. The automatically-triggered digital video imaging based code symbol reading system of claim 21, wherein said OS layer comprises one or more software modules selected from the group consisting of an OS kernal module, an OS file system module, and device driver modules.

24. The automatically-triggered digital video imaging based code symbol reading system of claim 22, wherein said SCORE layer includes one or more of software modules selected from the group consisting of a tasks manager module, an events dispatcher module, an input/output manager module, a user commands manager module, the timer subsystem module, an input/output subsystem module and a memory control subsystem module.

25. The automatically-triggered digital video imaging based code symbol reading system of claim 21, wherein said Application layer includes one or more software modules selected from the group consisting of a code symbol decoding module, a function programming module, an application events manager module, a user commands table module, and a command handler module.

26. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said housing is supportable on a countertop surface at a point-of-sale (POS) station or other work environment.

27. The automatically-triggered digital video imaging based code symbol reading system of claim 1, wherein said housing is hand-supportable.