Imaging engine employing planar light illumination and linear imaging

• US 7,743,990 B2
• Filed: 07/12/2006
• Issued: 06/29/2010
• Est. Priority Date: 11/24/2000
• 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, Schnee, Michael D.
• Primary Examiner(s): LE, THIEN MINH
• Application Number:
  US11/485,179
• Publication Number:
  US 20070090191A1
• Time in Patent Office: 1,448 Days
• Field of Search: 23546201-46245, 235/472.01, 235/472.02, 235/472.03, 235/454, 235/455
• US Class Current: 235/462.01
• 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, at least one 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 (which is integral to the engine housing) and provide field of views corresponding to the plurality of linear image arrays. The at least one illumination module produces planar light illumination that substantially overlaps the field of views corresponding to the plurality of linear imaging arrays. The 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 arrays and converts the row image data supplied thereto into digital form.

Claims

1. An 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 one linear imaging array has a variable line rate that is controlled by 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 the imaging engine with respect to target object(s).

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

4. The 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 convert the row image data supplied thereto into digital form.

5. The 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 imaging engine of claim 1, wherein the variable line rate is based upon velocity estimates derived from processing of pixel data values obtained from other linear imaging arrays disposed in the imaging engine.

7. The 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 imaging array.

8. The imaging engine of claim 7, wherein said line rate adjustment module is realized as part of a programmed controller.

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

10. The imaging engine of claim 1, wherein said output illumination control module is realized as part of a programmed controller.

11. The imaging engine of claim 1, wherein said supporting circuitry includes image processing circuitry, operably coupled to 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.

12. The imagine engine of claim 11, wherein said image processing circuitry comprises dedicated hardware selected from the group of:

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

13. The imagine engine of claim 11, wherein said image processing circuitry comprises one or more digital signal processing engines and associated memory.

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

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

16. The imaging engine of claim 15, wherein said at least one source of coherent illumination comprises at least one visible laser diode.

17. The imaging engine of claim 16, wherein said at least one source of coherent illumination comprises a plurality of visible laser diodes.

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

19. The imaging engine of claim 18, wherein said at least one source of incoherent illumination comprises at least one light emitting diode.

20. The imaging engine of claim 19, wherein said at least one source of incoherent illumination comprises a plurality of light emitting diodes.

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

22. An imaging engine comprising:

an engine housing;

a plurality of linear imaging arrays and image formation optics dispersed in said engine housing that provide field of views corresponding to the plurality of linear image arrays;

at least one illumination module dispersed in said engine housing, that produces planar light illumination that substantially overlaps the field of views corresponding to the plurality of linear imaging arrays; and

supporting circuitry disposed in said engine housing, 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 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; and

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.

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

24. The imaging engine of claim 23, wherein said at least one source of coherent illumination comprises at least one visible laser diode.

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

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

27. The imaging engine of claim 26, wherein said at least one source of incoherent illumination comprises at least one light emitting diode.

28. The imaging engine of claim 22, wherein said at least one source of incoherent illumination comprises a plurality of light emitting diodes.

29. The 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.