Method of illuminating objects at a point of sale (POS) station by adaptively controlling the spectral composition of the wide-area illumination beam produced from an illumination subsystem within an automatic digital image capture and processing system

• US 7,614,560 B2
• Filed: 10/24/2007
• Issued: 11/10/2009
• Est. Priority Date: 11/24/2000
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Veksland, Michael, Ren, Jie, Knowles, C. Harry, Xian, Tao, Liu, Yong, Good, Timothy, Giordano, Patrick, Schmidt, Mark, Kotlarsky, Anatoly, Furlong, John, Tao, Xi, Liu, JiBin, Essinger, Steven, Gardner, John, Kearney, Sean, Ellis, Duane, Ciarlante, Nicholas, Hernandez, Mark, Zhuo, Ming
• Primary Examiner(s): Kim; Ahshik
• Application Number:
  US11/977,430
• Publication Number:
  US 20080110992A1
• Time in Patent Office: 748 Days
• Field of Search: 235/462.24, 235/462.42, 235/462.01, 235/462.09, 235/468
• US Class Current: 235/462.42
• CPC Class Codes: A47F 9/046 Arrangement of recording means in or on check-out counters record carriers or readers per se G06K
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G06K 2207/1012 Special detection of object
• CPC Class Codes: G06K 7/10544 by scanning of the records by radiation in the optical part of the electromagnetic spectrum
• CPC Class Codes: G06K 7/10564 Light sources
• CPC Class Codes: G06K 7/10574 Multiple sources
• CPC Class Codes: G06K 7/10613 by rotation, e.g. polygon
• CPC Class Codes: G06K 7/10623 Constructional details
• CPC Class Codes: G06K 7/10693 for omnidirectional scanning
• 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 7/10782 Slot readers
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• 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 7/10861 sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48
• CPC Class Codes: G06Q 20/208 Input by product or record sensing, e.g. weighing or scanner processing
• CPC Class Codes: G06Q 30/06 Buying, selling or leasing transactions
• CPC Class Codes: G06V 10/141 Control of illumination
• CPC Class Codes: G07G 1/0036 Checkout procedures
• CPC Class Codes: G07G 1/0045 : with a code reader for reading of an identifying code of the article to be registered, e.g. barcode reader or radio-frequency identity [RFID] reader
• CPC Class Codes: G07G 3/00 : Alarm indicators, e.g. bells
• CPC Class Codes: G07G 3/006 : False operation

Abstract

A method of illuminating objects using adaptively controlled mixing of spectral illumination energy to form and detect digital images of objects at a POS. The method comprises providing, at a POS environment, a digital image capture and processing system having a system housing with an imaging window, and an area-type illumination and imaging station disposed within said system housing, for projecting a coextensive area-type illumination and imaging field (i.e. zone) through said imaging window into a 3D imaging volume during object illumination and imaging operations. As the object is moved through the 3D imaging volume, its motion is automatically detected, and signals indicative of said detected object motion are generated. In response to the generated signals, a first field of visible illumination is produced from an array of visible LEDs, simultaneously with a second field of invisible illumination from a array of infrared (IR) LEDs. These first and second fields of illumination spatially overlap and intermix with each other to produce a composite wide-area illumination beam that is at least substantially coextensive with the FOV. During object illumination and imaging operations, the relative power ratio (VIS/IR) of these fields of visible illumination and invisible illumination is adaptively controlled as one or more digital images of the illuminated object are formed and detected, captured and buffered, and ultimately processed so as to read one or more 1D and/or 2D code symbols graphically represented in the digital images.

Claims

1. A method of illuminating objects by adaptively controlling the spectral composition of illumination energy during the formation and detection of digital images of objects at a a point of sale (POS) station, said method comprising the steps of:

(a) at said POS station, providing an automatic digital image capture and processing system having a system housing with an imaging window, and an area-type illumination and imaging station disposed within said system housing, for projecting a coextensive area-type illumination and imaging field through said imaging window into a 3D imaging volume during object illumination and imaging operations, wherein said area-type illumination and imaging station includes (i) an image formation and detection (IFD) subsystem having an image sensing array and optics providing a field of view (FOV) on said image sensing array and extending into said 3D imaging volume, (ii) an illumination subsystem having an array of visible LEDs and an array of infrared (IR) LEDs for illuminating an object within said 3D imaging volume, with visible and invisible illumination, (iii) an illumination control subsystem for controlling said illumination subsystem, (iv) an image capturing and buffering subsystem for capturing and buffering digital images of the illuminated object detected by said image sensing array, and (v) a digital image processing subsystem for processing said captured and buffered digital images, and (vi) an automatic object detection subsystem for automatically detecting the object within said 3D imaging volume;

(b) moving the object through said 3D imaging volume, and said automatic object detection subsystem automatically detecting said object, and generating signals indicative of said detected object;

(c) in response to said generated signals, said illumination subsystem automatically producing a first wide-area field of visible illumination from said array of visible LEDs, simultaneously with a second wide-area field of invisible illumination from said array of IR LEDs, whereby said first and second wide-area fields of illumination spatially overlap and intermix with each other and produce a composite wide-area illumination beam that is at least substantially coextensive with said FOV, as said illumination control subsystem adaptively controls the relative power ratio of said fields of visible illumination and invisible illumination (VIS/IR), and said image formation and detection subsystem forms and detects one or more digital images of said illuminated object, during said object illumination and imaging operations;

(d) said image sensing array detecting one or more digital images of the illuminated object during object illumination operations;

(e) said image capturing and buffering subsystem capturing and buffering digital images of the illuminated object, detected by said image sensing array; and

(f) said digital image processing subsystem automatically processing said buffered digital images so as to read one or more 1D and/or 2D code symbols graphically represented in said digital images.

2. The method of claim 1, wherein during said step (c), said relative power ratio of visible illumination to invisible illumination (VIS/IR) is adaptively controlled so as to optimize said relative power ratio in effort to achieve sufficient image contrast in captured digital images to ensure satisfactory image processing.

5. The method of claim 1, wherein said automatic object motion detection subsystem comprises an imaging-based object motion detection subsystem including an area-type image acquisition subsystem and a digital signal processing chip to support digital image capture and processing operations required for real-time object motion detection.

6. The method of claim 1, wherein said 1D and/or 2D code symbols are selected from the group consisting of 1D bar code symbols, 2D bar code symbols and 2D data matrix symbols.

7. The method of claim 6, wherein said capturing one or more digital images of the illuminated object and measuring image contrast quality is carried out within said digital image processing subsystem.

9. The method of claim 1, wherein said 1D and/or 2D code symbols are selected from the group consisting of 1D bar code symbols, 2D bar code symbols and 2D data matrix symbols.

3. A method of illuminating objects by adaptively controlling the spectral composition of illumination energy during the formation and detection of digital images of objects at a point of sale (POS) station, said method comprising the steps of:

(a) at said POS station, providing an automatic digital image capture and processing system having a system housing with an imaging window, and an area-type illumination and imaging station disposed within said system housing, for projecting a coextensive area-type illumination and imaging field through said imaging window into a 3D imaging volume during object illumination and imaging operations, wherein said area-type illumination and imaging station includes (i) an image formation and detection (IFD) subsystem having an image sensing array and optics providing a field of view (FOV) on said image sensing array and extending into said 3D imaging volume, (ii) an illumination subsystem having an array of visible LEDs and an array of infrared (IR) LEDs for illuminating an object within said 3D imaging volume with visible and invisible illumination, (iii) an illumination control subsystem for controlling said illumination subsystem, (iv) an image capturing and buffering subsystem for capturing and buffering digital images of the illuminated object detected by said image sensing array, and (v) a digital image processing subsystem for processing said captured and buffered digital images, and (vi) an automatic object detection subsystem for automatically detecting the object within said 3D imaging volume;

(b) moving the object through said 3D imaging volume, and said automatic object detection subsystem automatically detecting said object, and generating signals indicative of said detected objects;

(c) in response to said generated signals, said illumination subsystem automatically producing a first wide-area field of visible illumination from said array of visible LEDs, simultaneously with a second wide-area field of invisible illumination from said array of IR LEDs, whereby said first and second wide-area fields of illumination spatially overlap and intermix with each other and produce a composite wide-area illumination beam that is at least substantially coextensive with said FOV, as said illumination control subsystem adaptively controls the relative power ratio of visible illumination to invisible illumination, and said image formation and detection subsystem forms and detects one or more digital images of said illuminated object, during said object illumination and imaging operations;

(d) said image sensing array detecting digital images of the illuminated object during object illumination operations;

(e) said image capturing and buffering subsystem capturing and buffering digital images of the illuminated object, detected by said image sensing array; and

(f) said digital image processing subsystem automatically processing said buffered digital images so as to read one or more 1D and/or 2D code symbols graphically represented in said digital images,

wherein during step (c), said illumination control subsystem adaptively controls the relative power ratio of visible illumination and invisible illumination (VIS/IR) during system operation by controlling the current supplied to said visible LEDs and IR LEDs during object illumination and imaging operations.

4. The method of claim 3, wherein during step (c), said current supplied to said visible LEDs and IR LEDs is controlled, during object illumination and imaging operations, by the following process:

(i) driving the visible LEDs and IR LEDs with a predetermined/default values of drive currents so as to illuminate the object with a spectral mixture of visible and invisible illumination;

(ii) capturing one or more digital images of the illuminated object and measuring image contrast quality so as to generate feedback or control data; and

(iii) using this feedback or control data to dynamically generate the necessary values for adjusted drive currents that are used to drive the visible LEDs and IR LEDs and produce an optimal mixture of illumination during object illumination and imaging operations.

8. The method of claim 3, wherein said automatic object motion detection. subsystem comprises an imaging-based object motion detection subsystem including an area-type image acquisition subsystem and a digital signal processing chip to support digital image capture and processing operations required for real-time object motion detection.