Hand-supportable imaging-based bar code symbol reader employing a tri-mode led-based illumination subsystem

• US 20050103858A1
• Filed: 07/20/2004
• Published: 05/19/2005
• 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, 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
• Granted Patent: US 7,225,988 B2
• Time in Patent Office: Days
• US Class Current: 235/462.220
• 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 ir-based object presence and range 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; and a system control subsystem. The LED-based multi-mode illumination subsystem produces three different fields of LED-based illumination in automatic response to the detection of different conditions within the FOV, by the automatic object presence and range detection subsystem.

Claims

1-56. -56. (canceled)

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

a hand-supportable housing;

a multi-mode 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-type 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;

an automatic object presence and range detection subsystem for producing an object detection field spatially encompassing said FOV, detecting the presence of an object within a near or far portion of said FOV, and generating a first control signal upon detection of an object to be imaged within the near-field portion of said FOV, and generating a second control signal upon detection of an object to be imaged within the far-field portion of said FOV;

a multi-mode LED-based illumination subsystem for producing fields of narrow-band illumination from LED-based illumination arrays,

wherein said multi-mode LED-based illumination subsystem produces a field of narrow-area narrow-band illumination within said FOV when said multi-mode image formation and detection subsystem is operated in said narrow-area image capture mode, and said automatic object presence and range detection subsystem detects an object within said FOV;

wherein said multi-mode LED-based illumination subsystem produces a field of wide-area narrow-band illumination within the near-field portion of said FOV when said multi-mode image formation and detection subsystem is operated in said wide-area image capture mode, and said automatic object presence and range detection subsystem detects an object within said near-field portion of said FOV;

wherein said multi-mode LED-based illumination subsystem produces a field of wide-area narrow-band illumination within the far-field portion of said FOV when said multi-mode image formation and detection subsystem is operated in said wide-area image capture mode, and aid automatic object presence and range detection subsystem detects an object within said far-field portion of said FOV;

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-based multi-mode illumination subsystem;

an image capturing and buffering subsystem for capturing and buffering 2-D digital images detected by the image formation and detection subsystem;

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

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 controlling the operation of said subsystems during system operation.

58. The hand-supportable digital imaging-based bar code symbol reading device of claim 57, wherein said hand-supportable housing further comprises a front panel having a light transmission window, and said LED-based multi-mode illumination subsystem comprises:

a first LED array for producing said field of narrow-area narrow-band illumination within said FOV;

a second LED array for producing said field of wide-area narrow-band illumination within the near-field portion of said FOV; and

a third LED array for producing said field of wide-area narrow-band illumination within the far-field portion of said FOV.

59. The hand-supportable digital imaging-based bar code symbol reading device of claim 58, wherein said first LED array comprises two pairs of LED light sources provided with cylindrical lenses, and mounted on left and right portions of said light transmission window.

60. The hand-supportable digital imaging-based bar code symbol reading device of claim 59, wherein during said narrow-area image capture mode, said first LED array produces said field of narrow-area narrow-band illumination within said FOV.

61. The hand-supportable digital imaging-based bar code symbol reading device of claim 60, wherein said field of narrow-area narrow-band illumination has a height less than 10 mm at far field, creating the appearance of substantially linear or rather planar illumination field.

62. The hand-supportable digital imaging-based bar code symbol reading device of claim 58, wherein said second LED array includes two sets of (flattop) LED light sources without any lenses mounted on the top and bottom portions of said light transmission window panel.

63. The hand-supportable digital imaging-based bar code symbol reading device of claim 62, wherein during said wide-area image capture mode, said second LED array produces said field of wide-area narrow-band illumination within the near-field portion of said FOV.

64. The hand-supportable digital imaging-based bar code symbol reading device of claim 63, wherein said third LED array includes two sets of LED light sources provided with spherical (i.e. plano-convex) lenses, mounted on the top and bottom portions of said light transmission window panel.

65. The hand-supportable digital imaging-based bar code symbol reading device of claim 64, wherein during said wide-area image capture mode, said third LED array produces said field of wide-area narrow-band illumination within the far-field portion of said FOV.

66. The hand-supportable digital imaging-based bar code symbol reading device of claim 65, wherein said field of narrow-area narrow-band illumination extends from about 30 mm to about 200 mm within the working range of the system, and covers both said near and far portions of said FOV.

67. The hand-supportable digital imaging-based bar code symbol reading device of claim 63, wherein said field of wide-area narrow-band illumination within the near-field portion of said FOV extends from about 0 mm to about 100 mm within the working range of the device.

68. The hand-supportable digital imaging-based bar code symbol reading device of claim 63, wherein said field of wide-area narrow-band illumination within the far-field portion of said FOV extends from about 100 mm to about 200 mm within the working range of the device.

69. The hand-supportable digital imaging-based bar code symbol reading device of claim 58, wherein said first LED array is designed to illuminate a thin area at the center of said FOV, measured from the boundary of the left side of said FOV to the boundary of the right side thereof.

70. The hand-supportable digital imaging-based bar code symbol reading device of claim of 57, wherein the object detection field is an IR-based object detection field, and said FOV and said IR-based object detection field are spatially co-extensive and said IR-based object detection field spatially overlaps said FOV along the entire working distance of said device.

71. The hand-supportable digital imaging-based bar code symbol reading device of claim 58, wherein said field of narrow-area narrow-band illumination, produced in response to the detection of an object, serves a dual purpose:

(1) it provides a visual indication to an operator about the location of said FOV of said device, and thus, serves as a field of view aiming instrument; and

(2) during the narrow-area image capture mode, the narrow-area field of narrow-band illumination is used to illuminate a thin area of said FOV within which an object resides, and a narrow 2-D image of the object can be rapidly captured (by a small number of rows of pixels in said image sensing array), buffered and processed in order to read any linear bar code symbols that may be represented therewithin.

72. The hand-supportable digital imaging-based bar code symbol reading device of claim 71, wherein the near field of wide-area narrow-band illumination with said near-field portion of said FOV is automatically generated by said second LED array in response to:

(1) the detection of any object within said near-field portion of said FOV by said automatic object presence and range detection subsystem; and

(2) one or more of following events, including, for example;

(i) failure of said image-processing based bar code symbol reader to successfully decode process a 1D bar code symbol during said narrow-area illumination mode;

(ii) detection of code elements such as control words associated with a 2-D bar code symbol; and

/or

(iii) detection of pixel data in the image which indicates that object was captured in a state of focus.

73. The hand-supportable digital imaging-based bar code symbol reading device of claim 72, wherein said near field of wide-area narrow-band illumination within said near-field portion of said FOV, produced in response to said one or more of the events, illuminates a wide area over a near-field portion of said FOV, within which an object resides, and a 2-D image of the object can be rapidly captured (by substantially all rows of said image sensing array), and buffered and decode-processed in order to read any 1D or 2-D bar code symbols that may be represented therewithin, at any orientation, and of virtually any bar code symbology.

74. The hand-supportable digital imaging-based bar code symbol reading device of claim 73, wherein the intensity of said field of wide-area narrow-band illumination within the near-field portion of said FOV is determined by how the LEDs associated with said second LED array are electrically driven by said LED-based multi-mode illumination subsystem.

75. The hand-supportable digital imaging-based bar code symbol reading device of claim 74, wherein the degree to which the LEDs are driven is determined by the intensity of reflected light measured near the image formation plane by said automatic light exposure measurement and control subsystem.

76. The hand-supportable digital imaging-based bar code symbol reading device of claim 77, wherein if the intensity of reflected light measured by said automatic light exposure measurement and illumination control subsystem is weak, indicative that the object exhibits low light reflectivity characteristics and a more intense amount of illumination will need to be produced by the LEDs to ensure sufficient light exposure on said image sensing array, then said automatic light exposure measurement and illumination control subsystem will drive the LEDs more intensely (e.g. at higher operating currents).

77. The hand-supportable digital imaging-based bar code symbol reading device of claim 72, wherein said field of wide-area arrow-band illumination within the far-field portion of said FOV is automatically generated by said third LED array in response to:

(1) the detection of any object within the near-field portion of said FOV by said automatic object presence and range detection subsystem; and

(2) one or more of following events, including, for example;

(i) failure of the image processor to successfully decode process a linear bar code symbol during the narrow-area illumination mode;

(ii) detection of code elements such as control words associated with a 2-D bar code symbol; and

/or

(iii) detection of pixel data in the image which indicates that object was captured in a state of focus.

78. The hand-supportable digital imaging-based bar code symbol reading device of claim 77, wherein the field of wide-area narrow-band illumination within the far-field portion of said FOV, produced in response to said one or more of the events, illuminates a wide area over a far-field portion of said FOV, within which an object resides, and a 2-D image of the object can be rapidly captured (by all rows of the image sensing array), buffered and processed in order to read any 1D or 2-D bar code symbols that may be represented therewithin, at any orientation, and of virtually any bar code symbology.

79. The hand-supportable digital imaging-based bar code symbol reading device of claim 78, wherein the intensity of said field of wide-area narrow-band illumination within the far-field portion of said FOV is determined by how the LEDs associated with said third LED array are electrically driven by said LED-based multi-mode illumination subsystem.

80. The hand-supportable digital imaging-based bar code symbol reading device of claim 79, wherein the degree to which the LEDs are driven (i.e. measured in terms of junction current) is determined by the intensity of reflected light measured near the image formation plane by said automatic light exposure measurement and illumination control subsystem.

81. The hand-supportable digital imaging-based bar code symbol reading device of claim 80, wherein if the intensity of reflected light detected by said automatic light exposure measurement and illumination control subsystem is weak, indicative that the object exhibits low light reflectivity characteristics and a more intense amount of illumination will need to be produced by the LEDs to ensure sufficient light exposure on said image sensing array, then said automatic light exposure measurement and illumination control subsystem will drive the LEDs more intensely (e.g. at higher operating currents).

82. The hand-supportable digital imaging-based bar code symbol reading device of claim 58, wherein during both near and far field wide-area illumination modes of operation, said automatic light exposure measurement and illumination control subsystem measures and controls the time duration which said LED-based multi-mode illumination subsystem exposes said image sensing array to narrow-band illumination (e.g. 633 nanometers, with approximately 15 nm bandwidth) during the image capturing/acquisition process, and automatically terminates the generation of such illumination when such computed time duration expires.

83. The hand-supportable digital imaging-based bar code symbol reading device of claim 58, wherein said field of wide-area narrow-band illumination within said far-field portion of said FOV is aimed by angling the plano-convex lenses before the LEDs in said third LED array.