Hand-supportable multi-mode digital imaging-based bar code symbol reader employing an automatic illumination and exposure control subsystem that automatically controls the operation of a multi-mode led-based illumination subsystem so that detected objects are sufficiently illuminated and good quality digital images thereof are formed and detected

• US 7,216,810 B2
• Filed: 07/20/2004
• Issued: 05/15/2007
• 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, 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:
  US10/895,271
• Publication Number:
  US 20050103857A1
• Time in Patent Office: 1,029 Days
• Field of Search: 235/462.22, 235/462.08, 235/462.41, 235/462.42, 235/462.11
• US Class Current: 235/462.22
• 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 device comprises: an automatic object presence detection subsystem; a multi-mode area-type image formation and detection subsystem having a field of view (FOV), and narrow-area and wide area image capture modes of operation; a multi-mode LED-based illumination subsystem having narrow-area and wide area illumination modes of operation; an automatic light exposure measurement and illumination control subsystem; an image capturing and buffering subsystem; an image-processing bar code symbol reading subsystem; an input/output subsystem; and a system control subsystem. In the digital imaging-based bar code reading device of the present invention, the automatic illumination and exposure control subsystem continuously measures the light exposure incident upon a central portion of the FOV, and automatically controls the operation of the LED-based multi-mode illumination subsystem so that the detected object is sufficiently illuminated and the multi-mode image formation and detection subsystem enabled to form and detect good quality digital images of the automatically detected object during illumination and imaging operations.

Claims

1. A hand-supportable digital imaging-based bar code symbol reading device comprising:

a hand-supportable housing;

a multi-mode area image formation and detection subsystem having image formation optics for producing a field of view (FOV) upon an object to be imaged and an area image sensing array for detecting imaged light reflected off the object during illumination operations in either (i) a narrow-area image capture mode in which a few central rows of pixels on the image sensing array are enabled, or (ii) a wide-area image capture mode in which substantially all rows of the image sensing array are enabled;

a multi-mode LED-based illumination subsystem for producing narrow and wide area fields of narrow-band illumination within said FOV during narrow-area and wide-area image capture modes, respectively;

an automatic object presence detection subsystem for producing an object detection field within said FOV and detecting objects present in said object detection field;

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 multi-mode LED-based illumination subsystem;

an image capturing and buffering subsystem for capturing and buffering 2-D images detected by said multi-mode image formation and detection subsystem;

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

an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device, and

a system control subsystem for automatically controlling the operation of each said subsystem;

wherein said automatic light exposure measurement and illumination control subsystem has a light collecting mirror and a photodiode arranged within said hand-supportable housing, wherein incident illumination is collected from a selected portion of the center of said FOV using said light collecting mirror, and then focused upon said photodiode for detection of the intensity of incident illumination and subsequent processing by said automatic light exposure measurement and illumination control subsystem, and

wherein said automatic object presence detection subsystem automatically detects the presence of an object within said object detection field, and in response thereto, said system control subsystem enables said automatic light exposure measurement and illumination control subsystem to continuously measure the light exposure within said selected portion of the center of said FOV and automatically control the illumination produced by said multi-mode LED-based illumination subsystem so that the detected object is sufficiently illuminated and said multi-mode image formation and detection subsystem forms and detects good quality digital images of illuminated objects.

2. The hand-supportable digital imaging-based bar code reading device of claim 1, wherein said multi-mode LED-based illumination subsystem comprises a first LED array for producing said narrow-area field of narrow-band illumination and also a second LED array for producing said wide-area field of narrow-band illumination.

3. The hand-supportable digital imaging-based bar code reading device of claim 1, wherein illumination is collected from the selected portion of the center of said FOV and automatically detected so as to generate a control signal for driving, at the proper intensity, said first LED array as well as said second LED array, so that said area image sensing array produces good quality digital images of illuminated objects.

4. The hand-supportable digital imaging-based bar code reading device of claim 1, wherein said automatic light exposure measurement and illumination control subsystem has two primary functions, namely:

(1) to measure, in real-time, the power density of light collected by said area image sensing array, and generate control signals indicating the amount of illumination required for good quality digital images; and

(2) in combination with an illumination array selection control signal produced by said system control subsystem, to automatically drive and control the output power of a selected one of said first and second LED arrays, so that objects within said FOV are optimally exposed to narrow-band illumination and good quality digital images are formed and detected at said area image sensing array.

5. The hand-supportable digital imaging-based bar code reading device of claim 1, wherein said automatic object presence detection subsystem produces an IR-based object detection field within said FOV for detecting objects present therein.