SYSTEMS AND METHODS FOR FORMING A COMPOSITE IMAGE OF MULTIPLE PORTIONS OF AN OBJECT FROM MULTIPLE PERSPECTIVES

• US 20090206161A1
• Filed: 02/12/2009
• Published: 08/20/2009
• Est. Priority Date: 02/12/2008
• Status: Active Grant

• Current Assignee: Datalogic Adc, Inc. (Datalogic S.p.A.)
• Original Assignee: Datalogic Scanning Incorporated (Datalogic S.p.A.)
• Inventors: Olmstead, Bryan L.
• Granted Patent: US 8,353,457 B2
• Time in Patent Office: Days
• US Class Current: 235/462.410
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• 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

Abstract

Various improved imager-based optical code readers and associated methods are disclosed herein. According to one embodiment, an imager-based method reads an optical code (which may be, for example, a linear optical code such as a bar code) on an object in a viewing volume. The method comprises dividing an image plane into a plurality of strip-shaped sections, viewing the object in the viewing volume from a plurality of perspectives, forming a plurality of strip-shaped images corresponding to the plurality of perspectives, respectively, thereby creating a composite image containing data from a plurality of perspectives, and processing at least a portion of the composite image so as to ascertain the information encoded in the optical code on the object in the viewing volume. Certain embodiments can mimic the performance of a laser-based scanner without a laser or moving parts but instead utilizing an electronic imaging device such as an imager.

Claims

1. A imager-based method for reading an optical code on an object in a viewing volume, the method comprising:

dividing an image plane into a plurality of strip-shaped sections;

viewing the object in the viewing volume from a plurality of perspectives;

forming a plurality of strip-shaped images corresponding to the plurality of perspectives, respectively, wherein the strip-shaped images are in the strip-shaped sections of the image plane, thereby creating a composite image containing data from the plurality of perspectives; and

processing at least a portion of the composite image so as to ascertain the information encoded in the optical code on the object in the viewing volume.

2. A method according to claim 1, wherein the optical code is a linear optical code, and the method further comprises:

processing a virtual scan line across at least one of the strips to decode the linear optical code.

3. A method according to claim 1, wherein the composite image comprises a rectangular array of pixels arranged as horizontal rows, wherein the imager is a row-wise rolling-reset imager, and wherein the strip-shaped sections are sets of N contiguous rows, wherein N is a positive integer.

4. A method according to claim 3, wherein the imager is a rolling-reset imager characterized by a frame rate, and wherein the step of forming a plurality of strip-shaped images corresponding to the plurality of perspectives, respectively, comprises:

sequentially forming the strip-shaped images on successive sets of N contiguous rows; and

repeating the step of forming a plurality of strip-shaped images corresponding to the plurality of perspectives, respectively, a whole number of times per frame of the rolling-reset imager.

5. A method according to claim 1, the method further comprising:

illuminating the object in the viewing volume from said plurality of perspectives in respective synchronicity with forming said plurality of strip-shaped images.

6. An imaging system for forming image data from an object bearing an optical code in a viewing volume, the imaging system comprising:

a camera comprising an imager and a lens, wherein the imager comprises a set of pixel imaging elements arranged in a two-dimensional imaging plane, and wherein the lens is positioned in front of the imager so as to focus a field of view onto substantially all of the pixel imaging elements of the imager;

a first set of a plurality of fixed mirrors placed in the field of view, wherein the mirrors in the first set split the field of view into plural portions and redirect said portions in different directions away from first set of mirrors;

a second set of at least one fixed mirror placed in a portion of the field of view as redirected by one of the first set of mirrors and positioned to redirect said potion of the field of view into the viewing volume from one or more perspectives, to thereby provide an image of at least a portion of the object from said perspectives on a portion of the pixel imaging elements of the imager; and

a decoder interfaced to the camera and configured to decode the optical code imaged by the imager.

7. An imaging system according to claim 6, wherein the imager is a rolling-reset imager.

8. An imaging system according to claim 6, wherein the mirrors in the first set of mirrors split the field of view into plural portions that comprise parallel strips across the imaging plane.

9. An imaging system according to claim 6, further comprising:

a plurality of sets of at least one fixed mirror placed in a portion of the field of view as redirected by one of the first set of mirrors, respectively, and positioned to redirect respective portion of the field of view into the viewing volume from one or more perspectives, to thereby provide an image of at least a portion of the object from a plurality of said perspectives on a respective portions of the pixel imaging elements of the imager.

10. An imaging system according to claim 6, further comprising:

an illumination source configured to shine light into the viewing volume by way of reflection via at least one mirror in the first set of mirrors and at least one mirror in the second set of mirrors.

11. An imaging system for forming image data from an object bearing an optical code in a viewing volume, the imaging system comprising:

an imager comprising a set of pixel imaging elements arranged in a two-dimensional imaging plane; and

a set of non-moving mirrors arranged to collect N views of the viewing volume from different perspectives and to reflect the N views onto N distinct portions of the imaging plane, wherein N>

8.

12. An imaging system according to claim 11, wherein the imager is a rolling-reset imager characterized by the set of pixel imaging elements being arranged in a rectangular array having rows and columns.

13. An imaging system according to claim 11, wherein each view of the viewing volume reflects off two different mirrors before reaching the imaging plane.

14. An imaging system according to claim 11, wherein the set of non-moving mirrors comprises:

a first set of mirrors configured to collect the N views of the viewing volume; and

a second set of mirrors oriented to reflect the N views from the first set of mirrors to the imaging plane.

15. An imaging system according to claim 11, further comprising:

a lens positioned in front of the imager.

16. An imaging system according to claim 11, further comprising:

an illumination source.

17. An imaging system according to claim 11, further comprising:

a signal processing unit operatively connected to the imager to receive image data.

18. An imaging system according to claim 11, wherein at least three of the N distinct portions are oriented in a common direction across the imaging plane regardless of a perspective from which a corresponding view is taken.

19. An imaging system according to claim 11, wherein said different perspectives are comparable to a set of perspectives of scan lines in a laser-based optical code scanner.

20. An imaging system according to claim 11, wherein at least one of the non-moving mirrors comprises a Fresnel prism.

21. A method for generating useful image data for an optical code on an object in a viewing volume using an imager and one or more fixed mirrors, the method comprising:

projecting onto a first portion of the imager via a first set of fixed mirrors a first partial view of the object from a first perspective into the viewing volume;

projecting onto a second portion of the imager via a second set of fixed mirrors a second partial view of the object from a second perspective into the viewing volume, wherein the second perspective is different from the first perspective in at least one of viewing position and viewing angle, and wherein the second portion of the imager is different from the first portion of the imager;

projecting onto a third portion of the imager a third via a third set of fixed mirrors partial view of the object from a third perspective into the viewing volume, wherein the third perspective is different from both the first perspective and the second perspective in at least one of viewing position and viewing angle, and wherein the third portion of the imager is different from both the first portion and the second portion of the imager, wherein the first, second and third portions of the imager are substantially aligned in a common direction across the imager.

22. A method according to claim 21, wherein the optical code is a one-dimensional optical code.

23. A method according to claim 22, further comprising:

attempting to decode the one-dimensional optical code along a virtual scan line traversing the first portion of the imager;

attempting to decode the one-dimensional optical code along a virtual scan line traversing the second portion of the imager; and

attempting to decode the one-dimensional optical code along a virtual scan line traversing the third portion of the imager.

24. A method according to claim 21, wherein each projecting step comprises reflecting the partial image off at least two mirrors and onto the imager.

25. A method according to claim 21, further comprising:

focusing each partial image onto the imager.

26. A method according to claim 21, further comprising:

illuminating the object in the viewing volume.

27. A method according to claim 26, wherein illuminating the object in the viewing volume comprises:

illuminating the area where the first portion of the object is at approximately the same time when the first portion of the imager is exposed for imaging;

illuminating the area where the second portion of the object is at approximately the same time when the second portion of the imager is exposed for imaging; and

illuminating the area where the third portion of the object is at approximately the same time when the third portion of the imager is exposed for imaging.

28. A method according to claim 27, wherein illuminating the area where the first portion of the object is comprises directing light at the object from the first perspective, illuminating the area where the second portion of the object is comprises directing light at the object from the second perspective, and illuminating the area where the third portion of the object is comprises directing light at the object from the third perspective.

29. A method according to claim 21, further comprising:

resetting the imager.

30. A system for generating useful image data for an optical code on an object in a viewing volume using an imager and one or more fixed mirrors, the system comprising:

a means for projecting onto a first portion of the imager via a first set of fixed mirrors a first partial view of the object from a first perspective into the viewing volume;

a means for projecting onto a second portion of the imager via a second set of fixed mirrors a second partial view of the object from a second perspective into the viewing volume, wherein the second perspective is different from the first perspective in at least one of viewing position and viewing angle, and wherein the second portion of the imager is different from the first portion of the imager;

a means for projecting onto a third portion of the imager via a third set of fixed mirrors a third partial view of the object from a third perspective into the viewing volume, wherein the third perspective is different from both the first perspective and the second perspective in at least one of viewing position and viewing angle, and wherein the third portion of the imager is different from both the first portion and the second portion of the imager, wherein the first, second and third portions of the imager are substantially aligned in a common direction across the imager.

31. A imager-based system for reading an optical code on an object in a viewing volume, the system comprising:

a means for viewing the object in the viewing volume from a plurality of perspectives;

a means for forming a plurality of strip-shaped images corresponding to the plurality of perspectives, respectively;

a means for creating a composite image by dividing an image into a plurality of strip-shaped sections, wherein the strip-shaped images are in the strip-shaped sections; and

a means for ascertaining the information encoded in the optical code on the object in the viewing volume.

32. An illumination method for use with a solid state imager comprising a surface having many closely spaced pixel imaging elements that together form a two-dimensional image of a field of view that spans a viewing area at a given distance from the imager, the method comprising:

providing illumination;

directing said illumination to less than all of the viewing area; and

forming a partial image, by use of the imager, of no more than the portion of the viewing area to which said illumination is directed.

33. An imager-based reader having illumination capability for machine vision of an object in a viewing volume, the reader comprising:

a solid state imager comprising a surface having many closely spaced pixel imaging elements that together form a two-dimensional image of a field of view;

a set of fixed mirrors positioned in the imager'"'"'s field of view and arranged to divide the imager'"'"'s field of view into multiple pieces and to direct the multiple pieces to portions of the viewing volume; and

an illumination source configured to shine light into the viewing volume by way of reflection via at least one mirror in the set of fixed mirrors.