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 20070138291A1
• Filed: 11/21/2006
• Published: 06/21/2007
• 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, Liu, Yong, Liu, Liang, Kotlarsky, Anatoly, Tao, Xi, Zhang, Wenhua, Hou, Rui, Yu, Hongpeng, Au, Ka
• Granted Patent: US 7,503,498 B2
• Time in Patent Office: Days
• US Class Current: 235/462.450
• 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 an image capture mode in which a plurality of rows of sensor elements in the 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 the 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 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 and the like 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 with 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.

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 the 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.

4. The hand-supportable digital image capture and processing system of claim 3, wherein said automatic light exposure measurement subsystem comprises a spherical/parabolic light reflecting/collecting mirror and photodiode arranged within said hand-supportable housing, and

wherein incident illumination is collected from a selected portion of the center of said FOV using a spherical light collecting mirror, and then focused upon a 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 3, wherein illumination is collected from the center 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. The hand-supportable digital image capture and processing system of claim 1, wherein said area-type image sensing array is operated in a single frame shutter mode and employs an exposure control method which ensure that all rows of pixels in said area-type image sensing array have a common integration time, thereby enabling said image capturing and buffering subsystem to capture high quality images even when the object is in a state of motion.

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 the area-type imaging sensing array;

(b) using said automatic light exposure measurement subsystem 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 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 in whatever image capture mode it may be configured, 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 a common integration time.

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 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.