Planar light illumination and imaging (PLIIM) system employing LED-based planar light illumination arrays (PLIAS) and an area-type image detection array

• US 7,104,455 B2
• Filed: 05/24/2002
• Issued: 09/12/2006
• Est. Priority Date: 06/07/1999
• Status: Expired due to Fees

• Current Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Original Assignee: Metrologic Instruments Incorporated (Honeywell International Inc.)
• Inventors: Zhu, Xiaoxun, Good, Timothy A., Knowles, C. Harry, Amundsen, Thomas, Schnee, Michael D., Tsikos, Constantine J.
• Primary Examiner(s): Kim, Ahshik
• Application Number:
  US10/156,744
• Publication Number:
  US 20030150917A1
• Time in Patent Office: 1,572 Days
• Field of Search: 235/462.01, 235/462.11, 235/462.22, 235/462.32, 235/462.43
• US Class Current: 235/462.32
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 19/0066 in the form of an LED array
• CPC Class Codes: G02B 19/009 for use with infrared radiation
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G02B 26/105 with one or more pivoting mirrors or galvano-mirrors G02B26/101 takes precedence
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: G02B 27/0966 Cylindrical lenses cylindrical lenses per se G02B3/06
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G06K 7/10554 Moving beam scanning
• CPC Class Codes: G06K 7/10683 Arrangement of fixed elements
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10861 sensing of data fields affixed to objects or articles, e.g. coded labels postal sorting B07C3/14, conveying articles B65G47/48
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

Methods of and systems for illuminating objects using planar light illumination beams having substantially-planar spatial distribution characteristics that extend through the field of view (FOV) of image formation and detection modules employed in such systems. Each planar light illumination beam is produced from a planar light illumination beam array (PLIA) comprising an plurality of planar light illumination modules (PLIMs). Each PLIM comprises a visible light emitting diode (LED), a focusing lens, and a cylindrical optical element arranged therewith. The individual planar light illumination beam components produced from each PLIM are optically combined to produce a composite substantially planar light illumination beam having substantially uniform power density characteristics over the entire spatial extend thereof and thus the working range of the system. Preferably, each planar light illumination beam component is focused so that the minimum beam width thereof occurs at a point or plane which is the farthest or maximum object distance at which the system is designed to acquire images, thereby compensating for decreases in the power density of the incident planar light illumination beam due to the fact that the width of the planar light illumination beam increases in length for increasing object distances away from the imaging optics. By virtue of the present invention, it is now possible to use both LEDs and high-speed CCD-type image detectors in conveyor, hand-held and hold-under type scanning applications alike, enjoying the advantages and benefits that each such technology has to offer, while avoiding the shortcomings and drawbacks hitherto associated therewith.

Claims

1. A planar light illumination and imaging (PLIIM) based system comprising:

a system housing having first, second and third light transmission apertures linearly aligned with and optically isolated from each other, and said third light transmission aperture being disposed between said first and second light transmission apertures;

an area-type image formation and detection module disposed in system housing, and having image forming optics with a field of view projectable through said third light transmission aperture and within a 3-D scanning region in which an object is present during object illumination and imaging operations;

a pair of planar light illumination arrays (PLIAs) disposed in said system housing, each said PLIA including a plurality of light emitting diodes (LEDs) arranged together in a linear manner and said PLIAs being arranged in relation to said area-type image formation and detection module, and for producing a pair of planar light illumination beams (PLIBs); and

a pair of planar light beam folding/sweeping mirrors for folding and sweeping said pair of PLIBs so that the optical paths of said PLIBs are oriented in an imaging direction that is coplanar with a section of said field of view of said area-type image formation and detection module as said PLIBs are swept through the 3-D scanning region during object illumination and imaging operations so that thee object can be simultaneously illuminated by said PLIBs and imaged within said field of view of said area-type image formation and detection module,

whereby a series of linear images of said object are sequentially detected by said area-type image formation and detection module over the photo-integration time period thereof so as to construct a two-dimensional image of said object.

2. The PLIIM based system of claim 1, which further comprises:

an image frame grabber for grabbing images formed and detected by said area-type image formation and detection module,

an image data buffer for buffering said grabbed images;

an image processing computer operably associated with said image data buffer, for processing said buffered images; and

a camera control computer for controlling said area-type image formation and said detection module, and said pair of PLIAs.

3. The PLIIM-based system of claim 2, which further comprises:

an image processing computer, operably connected to said image data buffer, for receiving and buffering said 2-D image, and for carrying out image processing algorithms and operators on said two-dimensional digital images.

4. The PLIIM-based t of claim 1, wherein said image forming optics have a fixed focal distance and a fixed focal length providing a fixed field of view.

5. The PLIIM-based system of claim 1, wherein said image forming optics have a variable focal distance and a fixed focal length providing a fixed field of view.

6. The PLIIM-based system of claim 1, wherein said image forming optics have a variable focal distance and a variable focal length providing a variable field of view.

7. The PLIIM-based system of claim 1, wherein said area-type image formation and detection module further comprises a 2-D array of photo-electronic detectors realized,

wherein each said PLIA comprises an array of planar light illumination modules (PLIMs), and

wherein each said PLIM comprises a visible light emitting diode (LED) source and optics for producing a planar light illumination beam (PLIB) component.

8. The PLIIM-based system of claim 1, wherein said system housing has a unitary construction.

9. A hand supportable bar code symbol reading system embodying the PLIIM-based system of claim 1.

10. A planar light illumination and imaging (PLIIM) based system comprising:

a system housing having first, second and third light transmission apertures linearly aligned with and optically isolated from each other, and said third light transmission aperture being disposed between said first and second light transmission apertures;

an area-type image formation and detection module disposed in system housing, and having image forming optics with a field of view projectable through said third light transmission aperture and within a 3-D scanning region in which an object is present during object illumination and imaging operations;

a stationary field of view folding mirror, disposed in said system housing, for folding the field of view of said area-type image formation and detection module in a predetermined direction with respect to said third light transmission aperture;

a pair of planar light illumination arrays (PLIAs) disposed in said system housing, each said planar light array (PLIA) including a plurality of light emitting diodes (LEDs) arranged together in a linear manner and said PLIAs being arranged in relation to said area-type image formation and detection module, and for producing a pair of planar light illumination beams (PLIBs); and

a pair of planar light beam folding/sweeping mirrors for folding and sweeping said pair of PLIBs so that the optical paths of said PLIBs are oriented in an imaging direction that is coplanar with a section of said field of view of said area-type image formation and detection module as said PLIBs are swept through the 3-D scanning region during object illumination and imaging operations so that the object can be simultaneously illuminated by said PLIBs and imaged within said field of view of said area-type image formation and detection module

whereby a series of linear images of said object are sequentially detected by said area-type image formation and detection module over the photo-integration time period thereof so as to construct a two-dimensional image of said object.

11. The PLIIM-based system of claim 10 which further comprises:

an image frame grabber for grabbing images formed and detected by said area-type image formation and detection module,

an image data buffer for buffering said grabbed images;

an image processing computer operably associated with said image data buffer, for processing said buffered images; and

a camera control computer for controlling said area-type image formation and said detection module, and said pair of PLIAs.

12. The PLIIM-based system of claim 11 which further comprises:

an image processing computer, operably connected to said image data buffer, for receiving and buffering said 2-D image, and for carrying out image processing algorithms and operators on said two-dimensional digital images.

13. The PLIIM-based system of claim 10, wherein said image forming optics have a fixed focal distance and a fixed focal length providing a fixed field of view.

14. The PLIIM-based system of claim 10, wherein said image forming optics have a variable focal distance and a fixed focal length providing a fixed field of view.

15. The PLIIM-based system of claim 10, wherein said image forming optics have a variable focal distance and a variable focal length providing a variable field of view.

16. The PLIIM-based system of claim 10, wherein said system housing has a unitary construction.

17. A hand-supportable bar code symbol reading system embodying the PLIIM-based system of claim 10.

18. A planar light illumination and imaging (PLIIM) based system comprising:

a system housing having first, second and third light transmission apertures linearly aligned with and optically isolated from each other, and said third light transmission aperture being disposed between said first and second light transmission apertures;

an area-type image formation and detection module disposed in system housing, and having image forming optics with a field of view projectable through said third light transmission aperture and within a 3-D scanning region in which an object is present during object illumination and imaging operations;

a planar light illumination array (PLIA) disposed in said system housing, each said planar light array (PLIA) including a plurality of light emitting diodes (LEDs) arranged together in a linear manner and said PLIAs being arranged in relation to said area-type image formation and detection module, and for producing a planar light illumination beam (PLIB); and

a planar light beam folding/sweeping mirror for folding and sweeping said PLIB so that the optical path of said PLIB is oriented in an imaging direction that is coplanar with a section of said field of view of said area-type image formation and detection module as said PLIB is swept through the 3-D scanning region during object illumination and imaging operations so that the object is simultaneously illuminated by said PLIB and imaged within said field of view of said area-type image formation and detection module,

whereby a series of linear images of said object are sequentially detected by said area-type image formation and detection module over the photo-integration time period thereof so as to construct a two-dimensional image of said object.

19. The PLIIM-based system of claim 18, which further comprises:

an image frame grabber for grabbing images formed and detected by said area-type image formation and detection module,

an image data buffer for buffering said grabbed images;

an image processing computer operably associated with said image data buffer, for processing said buffered images; and

a camera control computer for controlling said area-type image formation and said detection module, and said pair of PLIAs.

20. The PLIIM-based system of claim 18, which further comprises:

an image processing computer, operably connected to said image data buffer, for receiving and buffering said 2-D image, and for carrying out image processing algorithms and operators on said two-dimensional digital images.

21. The PLIIM-based system of claim 18, wherein said image forming optics have a fixed focal distance and a fixed focal length providing a fixed field of view.

22. The PLIIM-based system of claim 18, wherein said image forming optics have a variable focal distance and a fixed focal length providing a fixed field of view.

23. The PLIIM-based system of claim 18, wherein said image forming optics have a variable focal distance and a variable focal length providing a variable field of view.

24. The PLIIM-based system of claim 18, wherein said system housing has a unitary construction.

25. A hand-supportable bar code symbol reading system embodying the PLIIM-based system of claim 18.

26. The PLIIM-based system of claim 18, wherein said area-type image formation and detection module further comprises a 2-D array of photo-electronic detectors,

wherein each said PLIA comprises an array of planar light illumination modules (PLIMs), and

wherein each said PLIM comprises a visible light emitting diode (LED) source and optic for producing a planar light illumination beam (PLIB) component.