Optical coordinate input apparatus and position indicator thereof

• US 5,148,016 A
• Filed: 10/02/1990
• Issued: 09/15/1992
• Est. Priority Date: 10/26/1988
• Status: Expired due to Term

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Saito, Norio, Murakami, Azuma
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): LE, QUE TAN
• Application Number:
  US07/591,516
• Time in Patent Office: 714 Days
• Field of Search: 250/201.6, 250/221, 356/1, 356/4, 340/709, 340/710, 359/727, 359/728, 359/732
• US Class Current: 250/221
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G06F 3/0423 using sweeping light beams, e.g. using rotating or vibrating mirror

Abstract

The position of an object including a retroreflector is determined by scanning first and second optical beams toward an axis on a planar surface from spaced sites on opposite sides of the axis. The scanned beams are incident on and reflected from the retroreflector along coincident first and second paths between the sites and the retroreflector. Indications are derived of first and second angles between a baseline between the sites and the first and second paths extending between the sites and the retroreflector. In response to the known distance between the sites and the derived indications of the first and second angles a two-coordinate direction indication of the retroreflector position is derived. The retroreflector refracts and reflects the scanned optical beams incident thereon and refracts the beams reflected thereby.

Claims

1. An optical coordinate input apparatus comprising:

a position indicator having a mirror portion with mirrored surfaces in planes perpendicular to plane XY over which the position indicator is movable, the mirrored surfaces being substantially equidistant from a central axis extending perpendicular to the plane XY;

a light source for emitting laser beams;

a first rotary mirror having a rotational axis perpendicular to the plane XY;

a second rotary mirror disposed at a position removed from said first rotary mirror by a known distance and having a rotational axis perpendicular to the plane XY;

an optical system for directing said laser beams emitted from said light source to be incident on said first rotary mirror and said second rotary mirror;

a first photosensor for detecting said laser beam which is (a) incident on said first rotary mirror, (b) reflected by said first rotary mirror and a mirrored surface of said position indicator to traverse the same optical path as one of the laser beams incident on said mirrored surface, and (c) incident on said first rotary mirror before being reflected so as to be thus detected;

a second photosensor for detecting said laser beam which is (a) incident on said second rotary mirror, (b) reflected by said second rotary mirror and a mirrored surface of said position indicator to traverse the same optical path as another of the laser beams incident on said mirrored surface, and (c) incident on said second rotary mirror before being reflected so as to be thus detected;

angle detection means for detecting the rotational angles of said first rotary mirror and said second rotary mirror; and

coordinate calculating means for calculating a coordinate of a central position of said mirrored surface of said position indicator in accordance with an output signal from said first photosensor, an output signal from said second photosensor, and in response to the detected angles and the known distance.

3. An optical coordinate input apparatus according to claim 1, wherein said optical system comprises polarizing beam splitters each of which is disposed between said light source and said rotary mirrors and quarter wavelength plates each of which is disposed between said polarizing beam splitters and said rotary mirrors.

4. An optical coordinate input apparatus according to claim 1, wherein the optical path includes a cylindrical lens for causing a laser beam emitted from said light source to be in the form of a band, said lens being located in an optical path between said light source and said rotary mirror.

5. An optical coordinate input apparatus according to claim 1, wherein the optical path includes means for focusing said laser beam, said focusing means being located between said light source and said rotary mirror.

6. An optical coordinate input apparatus according to claim 1, wherein said coordinate calculating means includes a coordinate calculation instruction signal generating circuit for generating a signal for instructing calculation of the coordinates, said coordinate calculation means calculating the coordinates in response to an output signal from said coordinate calculation instruction signal generating circuit.

2. An optical coordinate input apparatus comprising:

a position indicator having a mirror portion with mirrored surfaces in planes perpendicular to plane XY over which the position indicator is movable, the mirrored surfaces being substantially equidistant from a central axis extending perpendicular to the plane XY;

a first rotary mirror having a rotational axis perpendicular to the plane XY;

a second rotary mirror disposed at a position removed from said first rotary mirror by a known distance and having a rotational axis perpendicular to the plane XY;

a light source for emitting laser beams;

an optical system for directing said laser beams emitted from said light source to be incident on each of said first rotary mirror and said second rotary mirror from a plurality of directions;

a first group of plural photosensors positioned to correspond to angles of said plurality of directions for detecting one of said plural laser beams which is (a) incident on said first rotary mirror, (b) reflected by said first rotary mirror and a mirrored surface of said position indicator to traverse the same optical path as one of the laser beams incident on said mirrored surface and (c) incident on said first rotary mirror before being reflected so as to be thus detected;

a second group of plural photosensors positioned to correspond to angles of said plurality of directions for detecting one of said plural laser beams which is (a) incident on said second rotary mirror, (b) reflected by said second rotary mirror and a mirrored surface of said position indicator to traverse the same optical path as another of the laser beams incident on said mirrored surface, and (c) incident on said second rotary mirror before being reflected so as to be thus detected;

angle detection means for detecting the rotational angles of said first rotary mirror and said second rotary mirror; and

coordinate calculating means for calculating a coordinate of a central position of said mirrored surface of said position indicator in accordance with an output signal from said first photosensor group, an output signal from said second photosensor group, and in response to the detected angles as well as the known distance.

7. A position indicator comprising a mirror portion with mirrored surfaces in planes perpendicular to plane XY over which the position indicator is movable, the mirrored surfaces being substantially equidistant from a central axis extending perpendicular to the plane XY and being on a body having a base with a planar surface that is movable over the plane XY, the central axis and the mirrored surfaces being at right angles to the planar surface of the base.

8. A position indicator according to claim 7, wherein said mirrored surface includes a sector of cylinder having an axis coincident with said central axis.

9. A position indicator according to claim 7, wherein said mirrored surface is convex.

10. A position indicator according to claim 7, wherein said mirrored surface is concave.

11. A position indicator according to claim 7 further comprising a pair of cross hairs having an intersection coincident with the central axis.

69. The position indicator of claim 8 wherein said sector has an extent of at least 180°

.

12. A position indicator for enabling the position of the indicator relative to a planar surface over which the indicator is moved to be optically determined comprising:

an annular optically transparent lens member having concentric inner and outer surfaces, said inner surface being a cylinder formed by rotating a straight line extending parallel to a concentric axis of the inner and outer surfaces about said concentric axis, said outer surface being a surface of revolution formed by rotating a convex line extending parallel to the concentric axis about said axis, said convex surface of revolution having a predetermined curvature to form a lens surface having an optical axis which extends along the radial direction of said annular shape, said lens having its focal point on said inner surface;

a reflection layer disposed on said inner surface of said annular lens member for reflecting light incident on a plane including said concentric axis and said radial optical axis, said reflected light being parallel to said incident light;

a support member for supporting said annular lens member and for enabling the lens member to be moved over said coordinate plane with said concentric axis retained perpendicular to a given coordinate plane; and

a collimating member for enabling a central point through which said concentric axis of said annular lens member passes to be optically aligned with a specific point on said coordinate plane.

13. A position indicator according to claim 12, wherein said annular lens member has a ground surface and includes high refracting factor glass.

14. A position indicator according to claim 12, wherein said reflection layer includes a thin metal layer.

15. A position indicator according to claim 12, wherein said support member comprises a bottom portion which is slidably positioned with respect to said coordinate plane and a portion for fixing said annular lens member in such a manner that said concentric axis is perpendicular to said bottom portion.

16. A position indicator according to claim 12, wherein said collimating member comprises:

(a) a fiber optic plate fastened to the inner portion of said annular lens member, and (b) a bottom portion slidably positioned with respect to said coordinate plane, an upper surface parallel to said bottom portion, and a parallel bundle of optical fibers for connecting said bottom portion and said upper surface.

17. Apparatus for determining the position of an object on a region of a planar surface, the region having an axis displaced from the periphery of the region, comprising:

means for deriving first and second scanned optical beams directed toward the axis from opposite sides thereof, the scanned beams being derived from first and second sites displaced from each other by a known distance along a base line,

a retroreflector on the object, the scanned optical beams being incident on and reflected from the retroreflector so that the first and second beams are respectively reflected from the retroreflector along first and second paths that are coincident with paths from the sites from the retroreflector,

optical detecting means responsive to optical energy reflected from the retroreflector and propagating along the first and second paths for deriving indications of first and second angles between the baseline and the first and second paths extending between the first and second sites and the retroreflector, and

means responsive to the known distance and the derived indications of the first and second angles for deriving a two-coordinate direction indication of the retroreflector position.

18. The apparatus of claim 17 wherein the retroreflector includes means for refracting and reflecting the scanned optical beams incident thereon and for refracting the beams reflected thereby.

19. The apparatus of claim 18 the means for refracting and reflecting includes multiple refracting elements and a reflector element positioned behind the elements, the configuration and positioning of the elements being such that the optical beam refracted by the refracting elements is focused on the reflector element to be reflected back to the detecting means via the refracting elements.

20. The apparatus of claim 19 wherein the reflector element includes plural concave surfaces, one of said surfaces being provided for each of the refracting elements.

21. The apparatus of claim 19 wherein the refracting elements include spherical globules.

22. The apparatus of claim 17 wherein the means for refracting and reflecting includes multiple refracting elements configured so that the beams incident thereon are focused on a back surface of each element to be reflected from the back surface.

24. The apparatus of claim 22 wherein the elements include a fiber optic cable wound on a cylindrical surface.

25. The apparatus of claim 17 wherein the optical detecting means is responsive only to approximately the peak amplitude of the optical energy reflected from the retroreflector.

26. The apparatus of claim 17 wherein the retroreflector includes an arcuate reflecting surface coaxial with an axis substantially at right angles to the planar surface.

27. The apparatus of claim 26 wherein the arcuate surface is concave in planes substantially at right angles to the planar surface.

28. The apparatus of claim 26 wherein the arcuate surface is convex in planes substantially at right angles to the planar surface.

29. The apparatus of claim 26 wherein the arcuate surface is straight in planes .substantially at right angles to the planar surface.

30. The apparatus of claim 29 wherein the reflecting surface is surrounded by a structure forming a lens for focusing optical energy in the paths on the reflecting surface.

31. The apparatus of claim 30 wherein the lens is a transparent structure having a relatively high index of refraction.

32. The apparatus of claim 26 wherein the object includes a pair of cross hair lines in a plane parallel to the planar surface and surrounded by the reflecting surface, the cross hair lines intersecting on the axis coaxial with the arcuate reflecting surface.

33. The apparatus of claim 17 wherein the optical detecting means includes first and second detectors respectively responsive to optical energy propagating away from the retroreflector along the first and second paths.

34. The apparatus of claim 17 further including means for varying the displacement of the sites relative to each other and for deriving a signal indicative of the distance between the sites along the baseline so that the signal has a value indicative of the known distance, the means for deriving a two-coordinate direction indication being responsive to the signal so that the derived position indication is controlled by the signal value indicative of the known distance.

35. The apparatus of claim 17 wherein the means for deriving the first and second scanned beams includes first and second reflectors, the first and second reflectors being turned on first and second axes extending at right angles to the planar surface at the first and second sites, respectively.

36. The apparatus of claim 35 wherein the means for deriving the first and second scanned beams includes means for directing plural optical beams toward the reflector at the first site from plural directions and for directing plural optical beams toward the reflector at the second site from plural directions, the reflectors at the first and second sites and the plural directions of the plural beams directed toward the first and second reflectors being arranged so that the first scanned beam is derived in response to only one of the plural beams directed toward the reflector at the first site and the second scanned beam is derived in response to only one of the plural beams directed toward the reflector at the second site.

37. The apparatus of claim 36 wherein the plural beams directed toward the first reflector propagate at right angles to each other and the plural beams directed toward the second reflector propagate along paths at right angles to each other.

38. The apparatus of claim 36 wherein four beams are directed from a source means for the beams toward the first reflector to propagate along paths at right angles to each other, and four beams are directed from a source means for the beams toward the second reflector to propagate along paths at right angles to each other.

39. The apparatus of claim 36 wherein the optical detecting means includes (a) plural detectors responsive to optical energy propagating away from the retroreflector via the first path and away from the first reflector via plural paths, one of which is associated with each of the plural optical beams directed toward the reflector at the first site, and (b) multiple detectors responsive to optical energy propagating away from the retroreflector via the second path and away from the second reflector via plural paths, one of which is associated with each of the plural optical beams directed toward the reflector at the second site.

40. The apparatus of claim 39 wherein the angle indication deriving means derives the indication for the first angle in response to the optical energy incident on only one of the plural detectors at a time and derives the indication for the second angle in response to the optical energy incident on only one of the multiple detectors at a time.

41. The apparatus of claim 35 wherein the optical detecting means includes (a) a first detector responsive to optical energy propagating away from the retroreflector along the first path and away from the first reflector, and (b) a second detector responsive to optical energy propagating away from the retroreflector along the second path and away from the second reflector.

42. The apparatus of claim 35 wherein the indications of the first and second angles are derived by detecting the relative time positions during rotation cycles of the first and second reflectors when optical energy reflected back to the first and second reflectors from the retroreflector has an amplitude in excess of a predetermined value.

43. The apparatus of claim 17 wherein the means for deriving the first beam includes a first polarizing beam splitter in a beam path between a source of the optical energy and a first reflector at the first site, the optical detecting means including a first detector in another beam path including the first beam splitter and first reflector, and the means for deriving the second beam includes a second polarizing beam splitter in a beam path between a source of the optical energy and a second reflector at the second site, the optical detecting means including a second detector in a further beam path including the second beam splitter and second reflector.

44. The apparatus of claim 43 further including first and second quarter wave length plates respectively in the beam paths between the first and second beam splitters and the first and second reflectors.

23. The apparatus of claim wherein the elements include spherical globules.

45. Apparatus for determining the position of an object on a region of a planar surface, the region having an axis displaced from the periphery of the region, comprising:

means for deriving first and second scanned optical beams directed toward the axis from opposite sides thereof, the scanned beams being derived from first and second sites displaced from each other by a known distance along a base line,

the scanned optical beams being incident on and reflected from the object so that the first and second beams are respectively reflected from the object along first and second paths that are coincident with paths from the sites toward the object,

optical detecting means responsive to optical energy reflected from the object and propagating along the first and second paths for deriving indications of first and second angles between the base line and the first and second paths extending between the first and second sites and the object,

means responsive to the known distance and the derived indications of the first and second angles for deriving a two-coordinate direction indication of the object position, and

means for varying the displacement of the sites relative to each other and for deriving a signal indicative of the distance between the sites along the baseline so that the signal has a value indicative of the known distance, the means for deriving a two-coordinate direction indication being responsive to the signal so that the derived position indication is controlled by the signal value indicative of the known distance.

46. The apparatus of claim 45 wherein the object includes a retroreflector on which the scanned optical beams are incident.

47. The apparatus of claim 45 wherein the means for deriving the first and second scanned beams includes first and second reflectors, the first and second reflectors being turned on first and second axes extending at right angles to the planar surface at the first and second sites, respectively.

48. The apparatus of claim 47 wherein the optical detecting means includes (a) a first detector responsive to optical energy propagating away from the retroreflector along the first path and away from the first reflector, and (b) a second detector responsive to optical energy propagating away from the retroreflector along the second path and away from the second reflector.

49. The apparatus of claim 47 wherein the indications of the first and second angles- are derived by detecting the relative time positions during rotation cycles of the first and second reflectors when optical energy reflected back to the first and second reflectors from the retroreflector has an amplitude in excess of a predetermined value.

50. Apparatus for determining the position of an object on a region of a planar surface, the region having an axis displaced from the periphery of the region, comprising:

means for deriving first and second scanned optical beams directed toward the axis from opposite sides thereof, the scanned beams being derived from first and second sites displaced from each other by a known distance along a base line,

the scanned optical beams being incident on and reflected from the object so that the first and second beams are respectively reflected from the object along first and second paths that are coincident with paths from the sites toward the object,

optical detecting means responsive to optical energy reflected from the object and propagating along the first and second paths for deriving indications of first and second angles between the base line and the first and second paths extending between the first and second sites and the object,

means responsive to the known distance and the derived indications of the first and second angles for deriving a two-coordinate direction indication of the object position,

the means for deriving the first and second scanned beams including first and second reflectors, the first and second reflectors being turned on first and second axes extending at right angles to the planar surface at the first and second sites, respectively, and

means for directing plural optical beams toward the reflector at the first site from plural directions and for directing plural optical beams toward the reflector at the second site from plural directions, the reflectors at the first and second sites and the plural directions of the plural beams directed toward the first and second reflectors being arranged so that the first scanned beam is derived in response to only one of the plural beams directed toward the reflector at the first site and the second scanned beam is derived in response to only one of the plural beams directed toward the reflector at the second site.

51. The apparatus of claim 50 wherein the plural beams directed toward the first reflector propagate along paths at right angles to each other and the plural beams directed toward the second reflector propagate along paths at right angles to each other.

52. The apparatus of claim 51 wherein four beams are directed from a source means for the beams toward the first reflector to propagate along paths at right angles to each other, and four beams are directed from a source means for the beams toward the second reflector to propagate along paths at right angles to each other.

53. The apparatus of claim 51 wherein the optical detecting means includes (a) plural detectors responsive to optical energy propagating away from the retroreflector via the first path and away from the first reflector via plural paths, one of which is associated with each of the plural optical beams directed toward the reflector at the first site, and (b) multiple detectors responsive to optical energy propagating away from the retroreflector via the second path and away from the second reflector via plural paths, one of which is associated with each of the plural optical beams directed toward the reflector at the second site.

54. The apparatus of claim 53 wherein the angle indication deriving means derives the indication for the first angle in response to the optical energy incident on only one of the plural detectors at a time and derives the indication for the second angle in response to the optical energy incident on only one of the multiple detectors at a time.

55. The apparatus of claim 50 wherein the object includes a retroreflector on which the scanned optical beams are incident.

56. The apparatus of claim 50 wherein the indications of the first and second angles are derived by detecting the relative time positions during rotation cycles of the first and second reflectors when optical energy reflected back to the first and second reflectors from the retroreflector has an amplitude in excess of a predetermined value.

57. Apparatus for determining the position of an object on a region of a planar surface, the region having an axis displaced from the periphery of the region, comprising:

means for deriving first and second scanned optical beams directed toward the axis from opposite sides thereof, the scanned beams being derived from first and second sites displaced from each other by a known distance along a base line,

the scanned optical beams being incident on and reflected from the object so that the first and second beams are respectively reflected from the object along first and second paths that are coincident with paths from the sites toward the object,

optical detecting means responsive to optical energy reflected from the object and propagating along the first and second paths for deriving indications of first and second angles between the base line and the first and second paths extending between the first and second sites and the object,

means responsive to the known distance and the derived indications of the first and second angles for deriving a two-coordinate direction indication of the object position,

the means for deriving the first beam including a first polarizing beam splitter in a beam path between a source of the optical energy and a first reflector at the first site,

the optical detecting means including a first detector in another beam path including the first beam splitter and first reflector,

the means for deriving the second beam including a second polarizing beam splitter in a beam path between a source of the optical energy and a second reflector at the second site, and

the optical detecting means includes a second detector in a further beam path including the second beam splitter and second reflector.

58. The apparatus of claim 57 further including first and second quarter wave length plates respectively in the beam paths between the first and second beam splitters and the first and second reflectors.

59. The apparatus of claim 57 wherein the object includes a retroreflector on which the scanned optical beams are incident.

60. The apparatus of claim 57 wherein the means for deriving the first and second scanned beams includes first and second reflectors, the first and second reflectors being turned on first and second axes extending at right angles to the planar surface at the first and second sites, respectively.

61. The apparatus of claim 60 wherein the indications of the first and second angles are derived by detecting the relative time positions during rotation cycles of the first and second reflectors when optical energy reflected back to the first and second reflectors from the retroreflector has an amplitude in excess of a predetermined value.

62. An implement movable over a planar surface and including structure for enabling the position of the implement to be determined optically in response to optical energy beams propagating parallel to the planar surface, the implement having an axis substantially perpendicular to the plane while the implement is moved over the plane, the implement comprising a planar face movable over the plane, an arcuate reflecting surface that moves with the planar face and is coaxial with and extends in the direction of the axis so that the propagating optical energy beams are incident thereon, and a structure forming a lens surrounding the arcuate reflecting surface forming a lens for focusing the optical energy beams propagating parallel to the planar surface on the reflecting surface.

63. The implement of claim 62 wherein the structure includes an exterior wall concentric with and extending in the direction of the axis, the optical energy beams being incident on the exterior wall prior to propagating to the reflecting surface.

64. The implement of claim 63 wherein the wall has a convex shape for focusing the optical energy propagating in the beams on the reflecting surface.

65. The implement of claim 64 wherein the lens has an index of refraction substantially in excess of unity.

66. The implement of claim 64 wherein the exterior wall and the reflecting surfaces are, in cross sections at right angles to the axis, sectors of circles having coincident centers on the axis.

67. The implement of claim 62 further including a reticle having a center coincident with the axis.

68. The implement of claim 67 further including a bundle of fiber optic elements extending in the direction of the axis between a top and bottom face of the implement and inside of the reflecting surface, the fiber optic elements optically coupling an image of the reticle to the top face so the image can be viewed by a user of the implement.

70. Apparatus for determining the position of an object on a region of a planar surface, the region having an axis displaced from the periphery of the region, comprising:

means for deriving first and second scanned optical beams directed toward the axis from opposite sides thereof, the scanned beams being derived from first and second sites displaced from each other by a known distance along a base line, the scanned optical beams being incident on and reflected from the object so that the first and second beams are respectively reflected from the object along first and second paths that are coincident with paths from the sites toward the object,

optical detecting means responsive only to approximately the peak amplitude optical energy reflected from the object and propagating along the first and second paths for deriving indications of first and second angles between the baseline and the first and second paths extending between the first and second sites and the object, and

means responsive to the known distance and the derived indications of the first and second angles for deriving a two-coordinate direction indication of the object position.

71. An optical coordinate input apparatus comprising

means forming a first planar surface on which the position of an object is to be optically detected;

the object including;

a base having a second planar surface that is movable over the first planar surface, mirrored surfaces substantially at right angles to the second planar surfaces and substantially equidistant from a central axis extending at right angles to the second planar surface;

an optical source for directing optical energy at the mirrored surfaces;

and means responsive to optical energy of the source incident on and reflected from the mirrored surfaces for indicating the location of the object on the first planar surface.

72. The apparatus of claim 71 wherein said mirrored surface includes a sector of a cylinder having an axis coincident with said central axis.

73. The apparatus of claim 71 wherein said mirrored surface is convex.

74. The apparatus of claim 71 wherein said mirrored surface is concave.

75. The apparatus of claim 71 wherein the object includes a pair of cross hairs having an intersection coincident with the central axis.