Data input device for tracking and detecting lift-off from a tracking surface by a reflected laser speckle pattern

• US 20050035947A1
• Filed: 08/15/2003
• Published: 02/17/2005
• Est. Priority Date: 08/15/2003
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Lutian, John Michael
• Granted Patent: US 7,227,531 B2
• Time in Patent Office: Days
• US Class Current: 345/166
• CPC Class Codes: G06F 2203/0338 Fingerprint track pad, i.e. fingerprint sensor used as pointing device tracking the fingertip image
• CPC Class Codes: G06F 3/0304 Detection arrangements using opto-electronic means constructional details of pointing devices not related to the detection arrangement using opto-electronic means G06F3/033; optical digitisers G06F3/042
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

A data input device for use with an optically rough tracking surface comprising a coherent light source projecting a coherent light beam and an optic positioned in the coherent light beam. The optic alters a wavefront profile of the coherent light beam so that the coherent light beam has a substantially constant phase relative to a plane perpendicular to the beam at a tracking distance from the optic. The coherent light beam is projected onto the tracking surface to reflect a substantially stable speckle pattern. A controller responsive to a detector correlates the substantially stable speckle pattern to track relative movement between the coherent light beam and the tracking surface. The controller suspends tracking of relative movement between the coherent light beam and the tracking surface when the detector detects a boiling speckle pattern.

Claims

1. A data input device for use with a tracking surface, said tracking surface being optically rough, said device comprising:

a coherent light source for projecting a coherent light beam onto said tracking surface to reflect a speckle pattern from the coherent light beam striking said tracking surface; and

an optic positioned in the coherent light beam for altering a wavefront profile of the coherent light beam so that the coherent light beam has a substantially constant phase relative to a plane perpendicular to said beam at a tracking distance from said optic, said tracking distance being different than a focal length of the optic, whereby said tracking surface reflects a substantially stable speckle pattern from the altered coherent light beam when the coherent light source and tracking surface are separated by about said tracking distance.

2. A device as set forth in claim 1 wherein said optic has a focal length greater than said tracking distance.

3. A device as set forth in claim 2 wherein said tracking distance is about the distance from the tracking surface to the optic when the device is at least one of contacting the tracking surface and nearly contacting the tracking surface.

4. A device as set forth in claim 3 wherein said tracking distance is between about 35% and about 90% of said focal length.

5. A device as set forth in claim 4 wherein said tracking distance is between about 50% and about 80% of said focal length.

6. A device as set forth in claim 5 wherein said tracking distance is between about 50% and about 75% of said focal length.

7. A device as set forth in claim 6 wherein said tracking distance is between about 60% and about 75% of said focal length.

8. A device as set forth in claim 7 wherein said tracking distance is between about 70% and about 75% of said focal length.

9. A device as set forth in claim 8 wherein said tracking distance is about 75% of said focal length.

10. A device as set forth in claim 3 wherein said focal length is between about 8 millimeters (0.31 inch) and about 30 millimeters (1.18 inches).

11. A device as set forth in claim 10 wherein said tracking distance is between about 4 millimeters (0.16 inch) and about 15 millimeters (0.59 inch).

12. A device as set forth in claim 10 wherein said focal length is between about 18 millimeters (0.79 inch) and about 25 millimeters (0.98 inch).

13. A device as set forth in claim 12 wherein said tracking distance is between about 9 millimeters (0.35 inch) and about 15 millimeters (0.59 inch).

14. A device as set forth in claim 13 wherein said focal length is about 25 millimeters (0.98 inch) and said tracking distance is about 12.5 millimeters (0.492 inch).

15. A device as set forth in claim 13 wherein said focal length is about 20 millimeters (0.79 inch) and said tracking distance is about 15 millimeters (0.59 inch).

16. A device as set forth in claim 13 wherein said focal length is about 18 millimeters (0.71 inch) and said tracking distance is about 13.5 millimeters (0.531 inch).

17. A device as set forth in claim 1 wherein said optic is a converging optic for focusing the coherent light beam as the coherent light beam strikes the tracking surface.

18. A device as set forth in claim 1 further comprising a detector associated with the coherent light source for detecting said speckle pattern reflected by the tracking surface and for imaging the detected speckle pattern.

19. A device as set forth in claim 18 further comprising a controller responsive to the detector for correlating the speckle pattern to track relative movement between the coherent light beam and the tracking surface when the speckle pattern is substantially stable.

20. A device as set forth in claim 1 wherein said optic alters the wavefront profile of said coherent light beam so that the coherent light beam is substantially out-of-phase across the coherent light beam within a plane perpendicular to said beam at a out-of-phase distance from said optic, such that locating the tracking surface at about said out-of-phase distance from said optic creates a boiling speckle pattern.

21. A device as set forth in claim 20 wherein said out-of-phase distance is about equal to the focal length of the optic.

22. A device as set forth in claim 21 wherein the speckle pattern comprises speckle grains, such that locating the tracking surface at about said focal point of said optic creates speckle grains that are on average too large to track relative to an illumination area of the coherent laser beam.

23. A device as set forth in claim 22 wherein said speckle grains too large to track have an average width of at least about 250 microns (9.8 mils (milliinches)).

24. A device as set forth in claim 20 further comprising a controller responsive to the detector for correlating the speckle pattern either to track relative movement between the coherent light beam and the tracking surface when the detector detects said substantially stable speckle pattern or to suspend tracking of relative movement between the coherent light beam and the tracking surface when the detector detects said boiling speckle pattern.

25. A. device as set forth in claim 24 wherein said controller indicates a lift-off condition when suspending tracking due to said boiling speckle pattern.

26. A device as set forth in claim 1 further comprising a housing, said coherent light source and said optic mounted on said housing.

27. A device as set forth in claim 26 wherein said housing is adapted to contact said tracking surface.

28. A device as set forth in claim 27 wherein said housing includes a support surface sized and shaped for contacting said tracking surface.

29. A device as set forth in claim 28 wherein said support surface is substantially continuous.

30. A device as set forth in claim 29 wherein said support surface is substantially planar.

31. A device as set forth in claim 1 wherein said optic includes at least one lens.

32. A device as set forth in claim 31 wherein said at least one lens is convex.

33. A device as set forth in claim 32 wherein said at least one lens is aspherical.

34. A device as set forth in claim 32 wherein said at least one lens is at least one of bi-convex and plano convex.

35. A device as set forth in claim 1 wherein the coherent light source draws less than about 1.0 mW (1.3 μ

horsepower).

36. A device as set forth in claim 1 wherein said coherent light source is a laser.

37. A device as set forth in claim 36 wherein said laser is a vertical cavity surface emitting laser (VCSEL).

38. A device as set forth in claim 1 wherein said coherent light beam has an illumination diameter of less than about 3.0 millimeters (120 mils (milliinches) at said tracking distance from said optic.

39. A device as set forth in claim 38 wherein said coherent light beam has an illumination diameter of less than about 2.0 millimeters (79 mils (milliinches)) at said tracking distance from said optic.

40. A device as set forth in claim 39 wherein said coherent light beam has an illumination diameter of less than about 1.0 millimeter (39 mils (milliinches)) at said tracking distance from said optic.

41. A device a set forth in claim 1 wherein said tracking surface is human skin for reflecting a speckle pattern from the coherent light beam striking the human skin.

42. A data input device for use with a tracking surface, said tracking surface being optically rough, said device comprising:

a coherent light source for projecting a coherent light beam onto said tracking surface to reflect a speckle pattern from said coherent light beam striking said tracking surface; and

an optic positioned in the coherent light beam for altering a wavefront profile of said coherent light beam to create a detection zone between about 35% and about 90% of the focal length of the optic, wherein relative movement within the detection zone between said coherent light beam and said tracking surface is detected based on the reflected speckle pattern, and a lift-off zone beyond about 90% of the focal length of the optic, wherein relative movement within the lift-off zone between said coherent light beam and said tracking surface is not detected.

43. A device as set forth in claim 42 wherein said tracking surface is not detected due to boiling of the reflected speckle pattern.

44. A device as set forth in claim 42 wherein said tracking surface is not detected due to increased speckle grain size.

45. A device as set forth in claim 42 wherein said detection zone is between about 50% and about 80% of said focal length.

46. A device as set forth in claim 45 wherein said detection zone is between about 50% and about 75% of said focal length.

47. A device as set forth in claim 42 wherein said optic is a converging optic for focusing the coherent light beam as the coherent light beam strikes the tracking surface.

48. A device as set forth in claim 42 wherein the speckle pattern comprises speckle grains, such that locating the tracking surface at about said focal length of said optic creates speckle grains that are on average too large to track relative to an illumination area of the coherent laser beam.

49. A device as set forth in claim 48 wherein said speckle grains too large to track have an average width of at least about 250 microns (9.8 mils (milliinches)).

50. A device as set forth in claim 42 further comprising a housing, said coherent light source and said optic mounted on said housing.

51. A device as set forth in claim 42 wherein said coherent light source is a laser.

52. A data input device for suspending tracking of movement comprising:

a source projecting a coherent light beam onto an optically rough tracking surface,

an optic focusing the coherent light beam,

a detector detecting out-of-phase coherent light reflected from the tracking surface as a speckle pattern, and

a controller determining if said data input device is spatially separated from said tracking surface by at least a lift-off detection distance as a function of the detected speckle pattern, said controller suspending tracking of relative movement between said data input device and said tracking surface when said data input device is spatially separated from said tracking surface by at least the lift-off detection distance.

53. A device as set forth in claim 52 wherein said optic alters the wavefront profile of said coherent light beam so that the coherent light beam has a substantially constant phase across at least one plane perpendicular to the coherent light beam.

54. A device as set forth in claim 52 wherein said controller maintains tracking of relative movement between said data input device and said tracking surface when said data input device is spatially separated from said tracking surface by less than said lift-off detection distance.

55. A device as set forth in claim 52 wherein said function of the detected speckle pattern is whether the speckle pattern is boiling.

56. A device as set forth in claim 52 wherein said function of the detected speckle pattern is whether the average width of the speckle grains of the speckle pattern are too large to track.

57. A method comprising:

projecting a coherent light beam from a data input device onto an optically rough tracking surface,

focusing the coherent light beam,

detecting out-of-phase coherent light reflected from the tracking surface as a speckle pattern,

determining if said data input device is spatially separated from said tracking surface by at least a lift-off detection distance as a function of the detected speckle pattern, and

suspending tracking of relative movement between said data input device and said tracking surface when said data input device is spatially separated from said tracking surface by at least the lift-off detection distance.