Method of illuminating objects during digital image capture operations by mixing visible and invisible spectral illumination energy at poing of sale (POS) environments

• US 20080169348A1
• Filed: 10/29/2007
• Published: 07/17/2008
• Est. Priority Date: 11/24/2000
• Status: Active Grant

• 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, Tao, Xi, Liu, JiBin, Essinger, Steven, Gardner, John, Kearney, Sean, Ellis, Duane, Ciarlante, Nicholas, Hernandez, Mark, Zhuo, Ming, Furlong, John A.
• Granted Patent: US 7,575,170 B2
• Time in Patent Office: Days
• 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 POS environments with sufficiently high image contrast and quality. The method comprises providing, at a POS environment, a digital image capture and processing system having a system housing with an imaging window, and a coplanar illumination and imaging station disposed within said system housing, for projecting a coplanar illumination and imaging plane through the imaging window into an imaging volume during object illumination and imaging operations. As the object is moved through the imaging volume, its motion is automatically detected, and signals indicative of said detected object are generated. In response to the generated signals, a first field of visible illumination is produced from an array of visible laser diodes (VLDs), simultaneously with a second field of invisible illumination from a array of infrared (IR) laser diodes (LDs). These first and second fields of illumination spatially overlap and intermix with each other and produce a composite planar illumination beam that is 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 are controlled as one or more linear 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. In an illustrative embodiment, during object illumination and imaging operations operation, the relative power ratio (VIS/IR) is adaptively controlled to form and detect digital images of objects at POS environments with sufficiently high image contrast and quality.

Claims

1. A method of illuminating objects during digital image capture operations by mixing visible and invisible spectral illumination energy at POS environments to form and detect digital images of objects at POS environments with sufficiently high image contrast and quality, said method comprising the steps of:

(a) at POS environment, providing a digital image capture and processing system having a system housing with an imaging window, and a coplanar illumination and imaging station disposed within said system housing, for projecting a coplanar illumination and imaging plane through said imaging window into an imaging volume during object illumination and imaging operations, wherein said coplanar illumination and imaging station includes (i) an image formation and detection (IFD) subsystem having a linear image sensing array and optics providing a field of view (FOV) on said linear image sensing array and extending into said imaging volume, (ii) an illumination subsystem having an array of visible laser diodes (VLDs) and an array of infrared (IR) laser diodes (LDs), (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 objects within said 3D imaging volume;

(b) moving the object through said imaging volume, and said automatic object motion 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 field of visible illumination from said array of VLDs, simultaneously with a second field of invisible illumination from said array of IR-LDs, whereby said first and second fields of illumination spatially overlap and intermix with each other a produce a composite planar laser illumination beam which is substantially coplanar with said FOV, as said illumination control subsystem controls the relative power ratio (VIS/IR) of said fields of visible illumination and invisible illumination, and said image formation and detection subsystem forms and detects one or more linear digital images of said illuminated object, during said object illumination and imaging operation;

(d) said image sensing array detecting linear 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 step (c), said illumination control subsystem controls the relative power ratio (VIS/IR) of visible illumination and invisible illumination during system operation by controlling the current supplied to said VLDs and IR-LDs during object illumination and imaging operations.

3. The method of claim 2, wherein during step (c), said current supplied to said VLDs and IR-LDs is controlled, during object illumination and imaging operations, by the following process:

(i) driving the VLDs and IR-LDs with a predetermined/default values of drive currents so as to illuminate the object with a spectral mixture of 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 the adjusted VLD and/or IR-LD current control signals that are used to drive the diodes and produce an optimal mixture of illumination during object illumination and imaging operations.

4. The method of claim 1, wherein said automatic object detection subsystem comprises an imaging-based object 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.

5. 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.

6. The method of claim 1, 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.

7. 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.