Hand-suportable imaging-based bar code symbol reader employing an automatic light exposure measurement and illumination control subsystem for measuring illumination exposure on CMOS image sensing array and controlling LED illumination array driver circuitry

• US 7,240,844 B2
• Filed: 07/28/2004
• Issued: 07/10/2007
• Est. Priority Date: 11/13/2003
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Knowles, C. Harry, Au, Ka Man, Liu, Yong, Liu, Liang, Schmidt, Mark, Ghosh, Sankar, Kotlarsky, Anatoly, Tao, Xi, Zhang, Wenhua, Amundsen, Thomas, Hou, Rui, Russell, Garrett, Byun, Sung, Yu, Hongpeng, Bonanno, John, Schnee, Michael, Spatafore, Pasqual
• Primary Examiner(s): Kim; Ahshik
• Application Number:
  US10/901,445
• Publication Number:
  US 20050116040A1
• Time in Patent Office: 1,077 Days
• Field of Search: 235/472.01, 235/462.01, 235/462.09, 235/462.22, 235/462.24, 235/462.25, 235/462.45, 235/462.42
• 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 imaging-based bar code symbol reading system comprises: an automatic object presence detection subsystem; an image formation and detection subsystem employing a CMOS area-type image detection array; an LED-based illumination subsystem employing a LED illumination array for generating a field of narrow-band LED illumination; an automatic light exposure measurement and illumination control subsystem employing LED illumination driver circuitry; an image capturing and buffering subsystem; an image-processing bar code symbol reading subsystem; an input/output subsystem; a narrow-band transmission-type optical filter subsystem; and a system control subsystem for controlling the subsystems. The time duration that the CMOS area-type image sensing array is exposed to narrow-band illumination, from the LED-based illumination array, is managed by controlling the time that the LED-based illumination array generates narrow-band illumination in response to first and second control activation signals generated by the CMOS image sensing array and the automatic object presence detection subsystem, respectively, aboard the system.

Claims

1. A digital imaging-based bar code symbol reading system having a working range comprising:

an image formation and detection subsystem having image formation optics for producing a field of view (FOV) upon an object to be imaged and a CMOS area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image-capture mode in which substantially all rows of the image sensing array are enabled, and when substantially all rows of pixels in said CMOS area-type image sensing array are in a state of integration operation and have a common integration time, automatically generating a first control activation signal;

an LED-based illumination subsystem for automatically producing a field of narrow-band illumination within said FOV from an LED illumination array during said image-capture mode, so that only narrow-band illumination (i) transmitted from said LED-based illumination subsystem, (ii) reflected/scattered from the illuminated object, and (iii) transmitted through a narrow-band transmission-type optical filter subsystem arranged before said CMOS area-type image sensing array, is detected by said CMOS area-type image sensing array while all other components of ambient light are substantially rejected;

an automatic object presence detection subsystem for automatically producing an object detection field that spatially encompasses said FOV along a substantial portion of said working range, and automatically detecting the presence of the object within said object detection field and generating said second control activation signal in response thereto;

an automatic light exposure measurement and illumination control subsystem for automatically measuring the light exposure incident upon a central portion of said FOV, and

controlling the operation of said LED illumination array during object illumination and imaging operations, so that said LED illumination array is driven in a precise manner that globally exposes said CMOS area-type image detection array with said narrow-band illumination only when substantially all rows of pixels in said CMOS area-type image detection array are in a state of integration operation and have a common integration time,

wherein the time duration that said CMOS area-type image sensing array is exposed to said narrow-band illumination is managed by said automatic light exposure measurement and illumination control subsystem controlling the time that said LED illumination array produces said field of narrow-band illumination in response to the generation of said first and second control activation signals;

an image capturing and buffering subsystem for capturing and buffering a digital image of the illuminated object formed and detected by said image formation and detection subsystem;

an image-processing based bar code symbol reading subsystem for processing said digital image captured and buffered by said image capturing and buffering subsystem, and reading 1D and 2D bar code symbols graphically represented therein;

a system control subsystem for controlling and coordinating the operation of said subsystems; and

a housing for containing said subsystems, and having a light transmission panel with an imaging window through which said FOV extends, said narrow-band illumination is projected,

and narrow-band illumination reflected and/or scattered off said object is re-transmitted toward said CMOS area-type image sensing array.

2. The digital imaging-based bar code symbol reading system of claim 1, wherein said LED illumination array includes two sets of flat-top LED light sources without any lenses, mounted on the top and bottom portions of said light transmission panel.

3. The digital imaging-based bar code symbol reading system of claim 2, wherein said LED illumination array further includes two sets of LED light sources provided with spherical lenses, mounted on the top and bottom portions of said light transmission panel.

4. The digital imaging-based bar code symbol reading system of claim 1, which further comprises an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding system.

5. The digital imaging-based bar code symbol reading system of claim 4, wherein said object detection field is an IR-based object detection field, and wherein said IR-based object detection field spatially overlaps said FOV along a substantial portion of the working range of said system.

6. The digital imaging-based bar code symbol reading system of claim 4, wherein said automatic object presence detection subsystem further comprises means for detecting the range of a detected object within a near-portion or a far-portion of said object detection field, and said second control activation signal comprises (i) a first-type second control activation signal indicative that a detected object is detected within said near-portion of said object detection field, and a (ii) second-type second control activation signal indicative that a detected object is detected within said far-portion of said object detection field.

7. The digital imaging-based bar code symbol reading system of claim 6, wherein said LED illumination array comprises a first LED illumination array for producing a field of narrow-band illumination over the near-portion of said object detection field, and a second LED illumination array for producing a field of narrow-band illumination over the far-portion of said object detection field;

and

wherein said automatic light exposure measurement and illumination control subsystem responds to said first control activation signal and said first and second types of second control activation signals to automatically drive either the first or second LED illumination array so that the time duration said the CMOS area-type image sensing array is exposed to narrow-band illumination from said first or second LED-based illumination array, is managed by controlling the time that the LED-based illumination array generates narrow-band illumination in response to said first and second control activation signals.

8. The digital imaging-based bar code symbol reading system of claim 1, wherein said housing has a hand-supportable form factor for using said system in hand-supported bar code reading applications.

9. The digital imaging-based bar code symbol reading system of claim 1, wherein said housing has a countertop-supportable form factor for using said system in presentation-type bar code symbol reading applications.