Hand-supportable digital image capturing and processing system, wherein only when all sensor elements in the image-sensing sensing array are activated and in state of integration, then narrow-band illumination is produced for illuminating objects in the field of view (FOV) of the system and simultaneously detected by a photodetector for measuring light exposure within the FOV, and also by an area-type image sensing array for detecting a digital image of said illuminated object

• US 20070131775A1
• Filed: 11/27/2006
• Published: 06/14/2007
• 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 7,503,499 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 portable digital image capturing and processing system comprising: an image formation and detection subsystem; a narrow-band illumination subsystem; a narrow-band transmission-type optical filter subsystem; an automatic light exposure measurement subsystem; and an automatic illumination control subsystem. The image formation and detection subsystem has an area-type image sensing array for detecting digital images of objects formed thereon by image formation optics providing a field of view (FOV) for the system. Within the FOV of the image formation and detection subsystem, the narrow-band illumination subsystem produces a field of narrow-band illumination consisting essentially of a narrow band of wavelengths of visible illumination. The narrow-band transmission-type optical filter subsystem transmits substantially only the narrow band of wavelengths of visible illumination produced from the narrow-band illumination subsystem, and rejects all other optical wavelengths outside the narrow band however generated by ambient illumination sources. The automatic light exposure measurement subsystem employs a photo-detector operated independently from the area-type image sensing array, for automatically measuring the light exposure incident upon a selected portion of the FOV, and producing an electrical signal representative of the light exposure measurement. Only when all sensor elements in the image-sensing sensing array are activated and in state of integration, then narrow-band illumination is produced for illuminating objects in FOV of the system and simultaneously detected by a photo-detector for measuring light exposure within the FOV, and also by an area-type image sensing array for detecting a digital image of said illuminated object.

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 rows of sensor elements in said area-type image sensing array are enabled so as to detect a 2D digital image of the object formed on said area-type image sensing array;

a narrow-band illumination subsystem, disposed in said hand-supportable housing, and having an narrow-band illumination array for producing a field of narrow-band illumination within the FOV of said image formation and detection subsystem during the image capture mode, wherein said field of narrow-band illumination consisting essentially of a narrow band of wavelengths of visible illumination produced from said narrow-band illumination subsystem;

a narrow-band optical filter subsystem, disposed in said hand-supportable housing, for transmitting substantially only the narrow band of wavelengths of visible illumination produced from said narrow-band illumination subsystem, and rejecting all other optical wavelengths outside said narrow band however generated by ambient illumination sources;

an automatic light exposure measurement subsystem disposed in said hand-supportable housing, employing a photo-detector operated independently from said area-type image sensing array, for automatically measuring the light exposure incident upon a selected portion of said FOV, and producing an electrical signal representative of said light exposure measurement;

an automatic illumination control subsystem disposed in said hand-supportable housing, for automatically controlling the operation of said narrow-band illumination subsystem,

wherein said automatic illumination control subsystem responds to said electrical signal and controls the duration of narrow-band illumination produced from said narrow-band illumination subsystem during said image capture mode;

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

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

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; and

a system control subsystem disposed in said hand-supportable housing, for controlling and/or coordinating the operation of the subsystem components described above;

wherein only when said plurality of rows of sensor elements in said area-type image sensing array are activated and in a state of integration, then said automatic illumination control subsystem automatically drives said narrow-band illumination array so that narrow-band illumination is produced from said narrow-band illumination subsystem, transmitted through said narrow-band transmission-type filter subsystem, reflects off said object, and simultaneously detected;

(i) by said photo-detector for measuring light exposure within the selected portion of said FOV, and

(ii) by said area-type image sensing array for producing 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 said image formation and detection subsystem, and automatically detecting the presence of an object in said FOV and generating a control activation signal in response to said object detection.

3. The hand-supportable digital image capture and processing system of claim 1, wherein said selected portion of said FOV is a central portion of said FOV.

4. The hand-supportable digital image capture and processing system of claim 1, wherein said narrow-band illumination comprises narrow-band illumination produced from an array of light emitting diodes (LEDs).

5. The hand-supportable digital image capture and processing system of claim 1, wherein said automatic light exposure measurement subsystem comprises a light collecting optical component arranged within said hand-supportable housing,

wherein incident narrow-band illumination is collected from the selected portion of said FOV using said light collecting optical component, and then focused upon said photodiode for detection of the intensity of collected narrow-band illumination and generation of an electrical signal corresponding to the detected intensity and for subsequent processing by said automatic light exposure measurement subsystem, so as to control the illumination produced by said narrow-band illumination subsystem and light exposure received by said area-type image sensing array.

6. The hand-supportable digital image capture and processing system of claim 1, wherein said narrow-band illumination is reflected off the object and collected from the selected portion of said FOV to produce said electrical signal, which in turn, is used to control the driving of said narrow-band illumination array at a predetermined intensity level so that said area-type image sensing array detects a digital image of the illuminated object having high image quality.

7. The hand-supportable digital image capture and processing system of claim 6, wherein said light collecting optical component comprises a light collecting mirror for focusing narrow-band illumination in the selected portion of said FOV, onto said photo-detector.

8. The hand-supportable digital image capture and processing system of claim 7, wherein said light collecting mirror comprises a parabolic mirror.

9. 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.

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.

12. The hand-supportable digital image capture and processing system of claim 1, wherein said narrow-band optical filter subsystem comprises first and second optical filter elements which cooperate to form said narrow-band optical filter subsystem and transmitting said narrow-band of wavelengths of visible illumination into said FOV, and rejecting all other optical wavelengths outside said narrow band however generated by ambient illumination sources.

13. The hand-supportable digital image capture and processing system of claim 12, wherein said hand-supportable housing has a light transmission aperture, said first optical filter is integrated with said light transmission aperture, and said second optical filter is disposed before said area-type image sensing array.

14. 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.