Imaging engine employing planar light illumination and linear imaging

• US 7,077,319 B2
• Filed: 06/27/2002
• Issued: 07/18/2006
• Est. Priority Date: 11/24/2000
• 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, Schnee, Michael D.
• Primary Examiner(s): LE, THIEN MINH
• Application Number:
  US10/186,268
• Publication Number:
  US 20030091244A1
• Time in Patent Office: 1,482 Days
• Field of Search: 23546201-46247, 235/472.01, 235/472.02, 235/472.03, 235/454, 235/455, 235/494, 235/470
• US Class Current: 235/462.1
• CPC Class Codes: G06K 2207/1018 Source control
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10752 Exposure time control

Abstract

An imaging engine includes a plurality of linear imaging arrays, image formation optics, one or more illumination module and supporting circuitry that are embodied within a modular engine housing. The plurality of linear imaging arrays and image formation optics are mounted on an optical bench and provide field of views corresponding to the plurality of linear image arrays. The one illumination module produces planar light illumination that substantially overlaps the field of views corresponding to the plurality of linear imaging arrays. The imaging engine can compensate for aspect ratio distortions that result from variations in velocity of engine with respect to target object(s). The engine can adjust the optical power level and/or illumination time period for the illumination that overlaps one or more of the FOVs of the linear imaging arrays of the engine for speckle reduction/constant white levels. The engine also supports image velocity estimation, aspect ratio compensation, jitter estimation and compensation, bar code detection, OCR, and image lift operations.

Claims

1. A self-contained imaging engine comprising:

a plurality of linear imaging arrays and image formation optics that provide field of views corresponding to the plurality of linear image arrays;

at least one illumination module that produces planar light illumination that substantially overlaps the field of views corresponding to the plurality of linear imaging arrays; and

supporting circuitry that operably cooperates with said plurality of linear image arrays and said at least one illumination module during operation of the imaging engine,

wherein said plurality of linear imaging arrays, image formation optics, at least one illumination module, and supporting circuitry are embodied within a modular engine housing.

2. The self-contained imaging engine of claim 1, wherein said supporting circuitry includes timing signal generation circuitry that supplies timing signals to the linear imaging arrays in order to read out the row image data produced by such linear imaging arrays.

3. The self-contained imaging engine of claim 1, wherein said supporting circuitry includes illumination control circuitry that supplies current to illumination sources of the at least one illumination module.

4. The self-contained imaging engine of claim 1, wherein said supporting circuitry includes analog-to-digital conversion circuitry, which optionally filters row data image signal supplied thereto (to remove unwanted noise components) and converts the row image data supplied thereto into digital form.

5. The self-contained imaging engine of claim 1, wherein said supporting circuitry includes data buffering circuitry, for storing the digital row image data generated by the analog-to-digital conversion circuitry and communicating the row image data stored therein over a data communication bus.

6. The self-contained imaging engine of claim 1, wherein one linear imaging array has a variable line rate that is controlled by the timing signals supplied thereto such that the image capture operations performed by the one linear imaging array maintains a substantially constant aspect ratio, to thereby compensate for aspect ratio distortions that result from variations in velocity of engine with respect to target object(s).

7. The self-contained imaging engine of claim 6, wherein the he variable line rate is based upon velocity estimates derived from processing of the pixel data values of other linear imaging arrays disposed therein.

8. The self-contained imaging engine of claim 1, wherein said supporting circuitry includes a line rate adjustment module that is operably coupled to timing signal generation circuitry and adjusts the variable line rate of the one linear image device (e.g., linear imaging array C).

9. The self-contained imaging engine of claim 8, wherein said line rate adjustment module is realized as part of a programmed controller.

10. The self-contained imaging engine of claim 1, wherein said supporting circuitry includes an output illumination control module that is operably coupled to the illumination control circuitry and adjusts the optical power level and/or illumination time period for illumination that overlaps one or more of the FOVs of the linear imaging arrays of the engine, to thereby reduce speckle noise and/or provide constant white level.

11. The self-contained imaging engine of claim 10, wherein said output illumination control module is realized as part of a programmed controller.

12. The self-contained imaging engine of claim 1, wherein said supporting circuitry includes imaging processing circuitry, operably coupled to the data buffering circuitry over the data communication bus, that realizes portions of image-based mechanisms for at least one of:

image velocity estimation, aspect ratio compensation, jitter estimation and compensation, bar code detection, OCR, and image lift.

13. The self-contained imagine engine of claim 12, wherein said imaging processing circuitry comprises dedicated hardware selected from the group of:

one or more FPGAs, one or more CPLDs, one or more ASICs.

14. The self-contained imagine engine of claim 12, wherein said imaging processing circuitry comprises one or more digital signal processing engines and associated memory.

15. The self-contained imaging engine of claim 1, wherein said planar light illumination overfills said field of views over a range of working distances of the engine during sequential image capture operations.

16. The self-contained imaging engine of claim 1, wherein said planar light illumination is produced from at least one source of coherent illumination.

17. The self-contained imaging engine of claim 16, wherein said at least one source comprises at least one visible laser diode.

18. The self-contained imaging engine of claim 17, wherein said at least one source comprises a plurality of visible laser diodes.

19. The self-contained imaging engine of claim 1, wherein said planar light illumination is produced from at least one source of incoherent illumination.

20. The self-contained imaging engine of claim 19, wherein said at least one source comprises at least one light emitting diode.

21. The self-contained imaging engine of claim 20, wherein said at least one source comprises a plurality of light emitting diodes.

22. The self-contained imaging engine of claim 1, wherein said planar light illumination is produced by at least one planar light illumination module comprising an illumination source, at least one focusing lens element, and at least one cylindrical lens element integrated into a modular housing disposed within said engine housing.

23. The self-contained imaging engine of claim 22, wherein said illumination source comprises at least one source of coherent illumination.

24. The self-contained imaging engine of claim 23, wherein said at least one source comprises at least one visible laser diode.

25. The self-contained imaging engine of claim 24, wherein said at least one source comprises a plurality of visible laser diodes.

26. The self-contained imaging engine of claim 22, wherein said illumination source comprises at least one source of incoherent illumination.

27. The self-contained imaging engine of claim 26, wherein said at least one source comprises at least one light emitting diode.

28. The self-contained imaging engine of claim 27, wherein said at least one source comprises a plurality of light emitting diodes.

29. The self-contained imaging engine of claim 22, wherein said planar light illumination is produced by planar light illumination arrays disposed on opposite sides of said plurality of linear imaging arrays, each planar light illumination array comprising at least one planar light illumination module.

30. The self-contained imaging engine of claim 22, wherein said planar light illumination is produced by multiple planar light illumination modules that are spaced apart and oriented on an optical bench in a manner that produces a composite beam of planar light illumination with substantial uniform intensity distribution over a range of working distances of the imaging engine.

31. The self-contained imaging engine of claim 1, wherein said supporting circuitry is disposed on at least on printed circuit board integral to said engine housing.