Hand-supportable digital image capturing and processing system employing an area-type image sensing array exposed to illumination from an LED-based illumination array only when all sensor elements in said image-sensing array are activated and in a state of integration

• US 7,503,498 B2
• Filed: 11/21/2006
• Issued: 03/17/2009
• Est. Priority Date: 11/13/2003
• Status: Expired due to Term

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Au, Ka Man, Liu, Yong, Liu, Liang, Kotlarsky, Anatoly, Tao, Xi, Zhang, Wenhua, Hou, Rui, Yu, Hongpeng
• Primary Examiner(s): Kim; Ahshik
• Application Number:
  US11/603,272
• Publication Number:
  US 20070138291A1
• Time in Patent Office: 847 Days
• Field of Search: 235/472.01, 235/462.41, 235/462.42, 235/462.45, 235/462.46
• 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 digital image capture and processing system comprises: an area-type image formation and detection subsystem having an area-type image detection array; an LED-based illumination subsystem having a LED-based illumination array; an automatic light exposure measurement and illumination control subsystem; an image capturing and buffering subsystem; and an image-processing subsystem. The LED array is automatically driven in a precise manner to globally expose the area-type image detection array with LED-based illumination only when substantially all of its rows of pixels are in a state of integration and have a common integration time, thereby enabling the capture of high quality images independent of the relative motion between the object and the hand-supportable digital image capture and processing system.

Claims

1. A hand-supportable digital image capture and processing system comprising:

a hand-supportable housing;

an image formation and detection subsystem, disposed in said hand-supportable housing, and having image formation optics for producing a field of view (FOV) upon an object to be imaged and an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in a single image frame capture mode in which a plurality of rows of sensor elements in said area-type image sensing array are enabled so as to detect a 2D digital image of the object on said area-type image sensing array;

an LED-based illumination subsystem, disposed in said hand-supportable housing, and having an LED-based illumination array for producing a field of LED-based illumination within the FOV of said image formation and detection subsystem during said single image frame capture mode;

an automatic illumination control subsystem disposed in said hand-supportable housing, for automatically controlling the operation of said LED-based illumination subsystem;

an image capturing and buffering subsystem disposed in said hand-supportable housing, for capturing and buffering 2-D digital images detected by said image formation and detection subsystem;

an image processing subsystem disposed in said hand-supportable housing, for processing 2-D digital images captured and buffered by said image capturing and buffering subsystem and producing processed image data; and

an input/output subsystem disposed in said hand-supportable housing, for outputting processed image data to an external host system or other information receiving or responding device;

a system control subsystem disposed in said hand-supportable housing, for activating and controlling said subsystem components described above;

wherein according to a global exposure control method carried out under said system control subsystem, when (i) said area-type image sensing array is activated during said single image frame capture mode, and (ii) said plurality of rows of sensor elements in said area-type image sensing array are in a state of integration and have a common integration time, then said automatic illumination control subsystem automatically drives said LED-based illumination array so that said plurality of rows of sensor elements in said area-type image sensing array are simultaneously exposed to LED-based illumination reflected and/or scattered off an object within said FOV, and thereby enabling said area-type image sensing array to detect a high quality digital image of the illuminated object, independent of the relative motion between said object and hand-supportable housing during said single image frame capture mode of operation.

2. The hand-supportable digital image capture and processing system of claim 1, which further comprises:

an automatic object presence detection subsystem for producing an object detection field within the FOV of said image formation and detection subsystem.

3. The hand-supportable digital image capture and processing system of claim 1, which further comprises:

an automatic light exposure measurement subsystem for automatically measuring the light exposure incident upon a central portion of said FOV, and in cooperation with said automatic illumination control subsystem, controlling the operation of said LED-based illumination subsystem.

8. The hand-supportable digital image capture and processing system of claim 1, wherein said area-type image sensing array comprises a CMOS image sensing array.

9. The hand-supportable digital image capture and processing system of claim 1, wherein said LED-based illumination comprises narrow-band LED-based illumination.

10. The hand-supportable digital image capture and processing system of claim 1, wherein said object bears a code symbol, and said image processing subsystem processes said 2-D digital images so as to read the code symbol and producing symbol character data representative of said read code symbol.

11. The hand-supportable digital image capture and processing system of claim 10, wherein 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.

4. A hand-supportable digital image capture and processing system comprising:

a hand-supportable housing;

an image formation and detection subsystem, disposed in said hand-supportable housing, and having image formation optics for producing a field of view (FOV) upon an object to be imaged and an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image frame capture mode in which a plurality of rows of sensor elements in said area-type image sensing array are enabled so as to detect a 2D digital image of the object on said area-type image sensing array;

an LED-based illumination subsystem, disposed in said hand-supportable housing, and having an LED-based illumination array for producing a field of LED-based illumination within the FOV of the image formation and detection subsystem during said image frame capture mode;

an automatic illumination control subsystem disposed in said hand-supportable housing, for automatically controlling the operation of said LED-based illumination subsystem;

an automatic light exposure measurement subsystem for automatically measuring the light exposure incident upon a central portion of said FOV, and in cooperation with said automatic illumination control subsystem, controlling the operation of said LED-based illumination subsystem;

an image capturing and buffering subsystem disposed in said hand-supportable housing, for capturing and buffering 2-D digital images detected by said image formation and detection subsystem;

an image processing subsystem disposed in said hand-supportable housing, for processing 2-D digital images captured and buffered by said image capturing and buffering subsystem and producing processed image data; and

an input/output subsystem disposed in said hand-supportable housing, for outputting processed image data to an external host system or other information receiving or responding device;

a system control subsystem disposed in said hand-supportable housing, for activating and controlling said subsystem components described above;

wherein when said area-type image sensing array is activated by said system control subsystem, and said plurality of rows of sensor elements in said area-type image sensing array are in a state of integration, then said automatic illumination control subsystem automatically drives said LED-based illumination array so that said area-type image sensing array is exposed to said LED-based illumination, and thereby enabling said area-type image sensing array to detect a high quality digital image of the object, independent of the relative motion between said object and hand-supportable housing;

wherein said automatic light exposure measurement subsystem comprises a light collecting mirror and photodiode arranged within said hand-supportable housing; and

wherein incident illumination is collected from a selected portion of said FOV using said light collecting mirror, and then focused upon said photodiode for detection of the intensity of reflected illumination and subsequent processing by said automatic light exposure measurement subsystem, and in cooperation with said automatic illumination control subsystem to control the illumination produced by said LED-based illumination subsystem.

5. The hand-supportable digital image capture and processing system of claim 4, wherein illumination is collected from the center portion of said FOV and automatically detected so as to generate a control signal for driving, at the proper intensity, said LED-based illumination array, so that the area-type image sensing array produces digital images of illuminated objects of sufficient brightness.

6. A hand-supportable digital image capture and processing system comprising:

a hand-supportable housing;

an image formation and detection subsystem, disposed in said hand-supportable housing, and having image formation optics for producing a field of view (FOV) upon an object to be imaged and an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in a single image frame capture mode in which a plurality of rows of sensor elements in said area-type image sensing array are enabled so as to detect a 2D digital image of the object on said area-type image sensing array;

an LED-based illumination subsystem, disposed in said hand-supportable housing, and having an LED-based illumination array for producing a field of LED-based illumination within the FOV of said image formation and detection subsystem during said single frame image capture mode;

an automatic illumination control subsystem disposed in said hand-supportable housing, for automatically controlling the operation of said LED-based illumination subsystem;

an image capturing and buffering subsystem disposed in said hand-supportable housing, for capturing and buffering 2-D digital images detected by said image formation and detection subsystem;

an image processing subsystem disposed in said hand-supportable housing, for processing 2-D digital images captured and buffered by said image capturing and buffering subsystem and producing processed image data; and

an input/output subsystem disposed in said hand-supportable housing, for outputting processed image data to an external host system or other information receiving or responding device;

a system control subsystem disposed in said hand-supportable housing, for activating and controlling said subsystem components described above;

wherein according to a global exposure control method, said area-type image sensing array is activated and said plurality of rows of sensor elements are in a state of integration and have a common integration time, before said automatic illumination control subsystem automatically drives said LED-based illumination array so that all rows of said area-type image sensing array are simultaneously exposed to LED-based illumination which reflects and/or scatters off the object within said FOV, and thereby enabling said area-type image sensing array to detect a high quality 2-D digital image of the object formed therein, and independent of the relative motion between said object and hand-supportable housing.

7. The hand-supportable digital image capture and processing system of claim 6, wherein said global exposure control method comprises:

(a) selecting the single frame shutter mode of operation for said area-type imaging sensing array;

(b) using an automatic light exposure measurement subsystem in said hand-supportable housing to continuously collect illumination from a portion of the FOV, detect the intensity of the collected illumination, and generate an electrical analog signal corresponding to the detected intensity, for subsequent processing;

(c) activating said area-type image sensing array so that its rows of pixels begin to integrate photonically-generated electrical charge in response to the formation of an optical image onto said area-type image sensing array by said image formation optics;

(d) using said area-type image sensing array to automatically (i) generate an electronic rolling shutter (ERS) digital pulse signal when all rows of pixels in the image sensing array are operated in a state of integration, and (ii) provide the ERS pulse signal to said automatic light exposure measurement subsystem so as to activate light exposure measurement and illumination control functions/operations therewithin;

(e) upon activation of light exposure measurement and illumination control functions within said automatic light exposure measurement subsystem, (i) processing the electrical analog signal being continuously generated therewithin, (ii) measuring the light exposure level within a central portion of the FOV, and (iii) generating an auto-exposure control signal for controlling the generation of visible illumination from said LED-based illumination array; and

(f) using the auto-exposure control signal to drive said LED-based illumination array and illuminate the field of view of said area-type image sensing array precisely when substantially all rows of pixels in said area-type image sensing array are in a state of integration, thereby ensuring that substantially all rows of pixels in said area-type image sensing array have said common integration time.