Method and apparatus for capturing an image of a moving object

• US 20070272841A1
• Filed: 05/25/2006
• Published: 11/29/2007
• Est. Priority Date: 05/25/2006
• Status: Active Grant

• Current Assignee: Microvision, Inc.
• Original Assignee: Microvision, Inc.
• Inventors: Wiklof, Christopher A.
• Granted Patent: US 7,501,616 B2
• Time in Patent Office: Days
• US Class Current: 250/234
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G06V 10/10 Image acquisition document image scanning and transmission H04N1/00; control of digital cameras H04N23/60

Abstract

A scanned beam imager or laser scanner is operable to scan an object moving through its field-of-view. The system may include means for detecting direction and/or speed of the object. The velocity detection means may include sensors, an interface for receiving velocity information from other system elements, or image analysis that examines the skew, stretch, or compression in images. Responsive to object movement direction and speed, the scanned beam imager may alter its pixel capture rate and/or its scan rate to compensate. Alternatively or in combination, the imager may perform software-based image motion compensation. In some embodiments, the system may allow the image capture region to pace objects moving rapidly through its field-of-view.

Claims

1. A laser scanner, comprising;

a beam director for scanning a beam of light across a field-of-view,

a light detector for detecting light from the beam scattered by the field-of-view, and

a controller that modifies at least one parameter of said beam director responsive to the motion of objects in the field-of-view.

2. The laser scanner of claim 1, further comprising;

a motion detector coupled to said controller for measuring the motion of objects in the field-of-view.

3. The laser scanner of claim 2, wherein said motion detector includes an interface for receiving motion information.

4. The laser scanner of claim 2, wherein said motion detector includes software for analyzing the apparent motion in captured images.

5. The laser scanner of claim 4, wherein said software for analyzing the apparent motion in captured images includes software for examining the skew of a machine readable symbol.

6. The laser scanner of claim 4, wherein said software for analyzing the apparent motion in captured images includes software for examining the elongation or compression of a machine readable symbol.

7. The laser scanner of claim 2, wherein said motion detector includes a velocimeter.

8. The laser scanner of claim 1, wherein the at least one beam director parameter includes scan rate.

9. The laser scanner of claim 6, wherein the beam director parameters may be adjusted to allow the scanning beam to pace objects in the field-of-view.

10. The laser scanner of claim 9, wherein the pacing of objects includes allowing the object to travel faster than the vertical scan.

11. The laser scanner of claim 9, wherein the pacing of objects includes moving the vertical scan faster than the object speed.

12. The laser scanner of claim 1, wherein said beam director directs the beam in two dimensions across the field-of-view.

13. The laser scanner of claim 1, wherein said beam director further comprises;

a laser diode for emitting a non-scanning beam, and

a moving mirror for dynamically deflecting the non-scanning beam across the field-of-view.

14. The laser scanner of claim 13, wherein said moving mirror includes a MEMS scanner.

15. The laser scanner of claim 1, wherein said controller further modifies at least one parameter of said light detector responsive to the motion of objects in the field-of-view.

16. The laser scanner of claim 15, wherein the at least one parameter of said light detector includes a frequency pass band.

17. The laser scanner of claim 15, wherein the at least one parameter of said light detector includes a pixel phase offset.

18. The laser scanner of claim 1, wherein said controller further generates a two-dimensional image of the field-of-view.

19. The laser scanner of claim 1, wherein said controller further includes a bar code decoder and the controller further decodes bar codes in the field-of-view.

20. A scanned beam imager, comprising;

a beam director for scanning a beam of light across a field-of-view,

a light detector for detecting light from the beam scattered by the field-of-view, and

a controller that modifies the phase of pixels captured by said light detector responsive to the motion of objects in the field-of-view.

21. The scanned beam imager of claim 20, further comprising a motion detector coupled to said controller for measuring the motion of objects in the field-of-view.

22. The scanned beam imager of claim 21, wherein said motion detector includes an interface for receiving motion information.

23. The scanned beam imager of claim 21, wherein said motion detector includes software for analyzing the apparent motion in captured images.

24. The scanned beam imager of claim 23, wherein said software for analyzing the apparent motion in captured images includes software for examining the skew of a machine readable symbol.

25. The scanned beam imager of claim 23, wherein said software for analyzing the apparent motion in captured images includes software for examining the elongation or compression of a machine readable symbol.

26. The scanned beam imager of claim 21, wherein said motion detector includes a velocimeter.

27. The scanned beam imager of claim 20, wherein said beam director directs the beam in two dimensions across the field-of-view.

28. The scanned beam imager of claim 20, wherein said beam director further comprises;

a laser diode for emitting a non-scanning beam, and

a scanning mirror for deflecting the non-scanning beam across the field-of-view.

29. A method for capturing an image from a moving object, comprising the steps of;

receiving motion information about an object in a field-of-view,

selecting at least one scanning parameter responsive to the received object motion information,

scanning a beam of light across the field-of-view using the selected at least one scanning parameter, and

detecting light scattered by the field-of-view.

30. The method for capturing an image from a moving object of claim 29, wherein said step of receiving motion information includes receiving data through an interface.

31. The method for capturing an image from a moving object of claim 29, wherein said step of receiving motion information includes receiving data from a velocimeter.

32. The method for capturing an image from a moving object of claim 29, wherein said step of receiving motion information includes analyzing the apparent motion in captured images.

33. The method for capturing an image from a moving object of claim 32, wherein said analyzing the apparent motion in captured images includes examining, in a machine readable symbol, at least one of the parameters consisting of skew, elongation, and compression.

34. The method for capturing an image from a moving object of claim 29, wherein said at least one scanning parameter includes vertical scan direction.

35. The method for capturing an image from a moving object of claim 29, wherein said at least one scanning parameter includes vertical scan rate.

36. The method for capturing an image from a moving object of claim 29, wherein said at least one scanning parameter includes horizontal scan amplitude.

37. The method for capturing an image from a moving object of claim 29, wherein said at least one scanning parameter includes pixel phase.

38. The method for capturing an image from a moving object of claim 29, wherein said step of selecting at least one scanning parameter responsive to the received object motion information, includes selecting a scan rate to pace the moving object.

39. The method for capturing an image from a moving object of claim 38, wherein said image comprises a series of one-dimensional lines.

40. The method for capturing an image from a moving object of claim 29, wherein said image comprises a two-dimensional image.