Touch screen signal processing

• US 20050190162A1
• Filed: 01/11/2005
• Published: 09/01/2005
• Est. Priority Date: 02/14/2003
• Status: Active Grant

• Current Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Next Holdings Ltd. (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Newton, John David
• Granted Patent: US 7,629,967 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A touch screen which uses light sources at one or more edges of the screen which directs light across the surface of the screen and at least two cameras having electronic outputs located at the periphery of the screen to receive light from said light sources. A processor receives the outputs of said cameras and employs triangulation techniques to determine the location of an object proximate to said screen. Detecting the presence of an object includes detecting at the cameras the presence or absence of direct light due to the object, using a screen surface as a mirror and detecting at the cameras the presence or absence of reflected light due to an object. The light sources may be modulated to provide a frequency band in the output of the cameras.

Claims

1. A touch display comprising:

a screen for a user to touch and view an image on or through;

light sources at one or more edges of said screen, said light sources directing light across the surface of said screen;

means for modulating said light from said light sources at a frequency within an imageable range of said cameras;

at least two cameras having outputs, each said camera located at the periphery of said screen to image the space in front of said screen, said output including a scanned image;

means for processing said outputs to detect the level of light, said light including;

direct light from said light sources, and/or

reflected light from said light sources;

means for excluding image data outside said modulation frequency;

a processor receiving the processed outputs of said cameras, said processor employing triangulation techniques and said processed outputs to determine whether the processed outputs indicate the presence of an object proximate to said screen and if so the location of said object.

2. A touch display as claimed in claim 1 wherein said processed output indicates the relative bearing of a presumed object location relative to said camera.

3. A touch display as claimed in claim 1 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

4. A touch display as claimed in claim 1 wherein said processor determines the location of said object as a planar screen co-ordinate.

5. A touch display as claimed in claim 1 wherein said light sources are behind said screen arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen.

6. A touch display as claimed in claim 1 wherein said cameras are line scan cameras, said camera output including information on line scanned and said processor using said information in determining the location of said object.

7. A touch display as claimed in claim 1 wherein said means for processing said outputs includes said means for excluding image data outside said frequency band and said means for excluding image data outside said frequency includes filtering.

8. A touch display as claimed in claim 7 wherein filtering includes applying a filter selected from the group consisting of:

a comb filter;

a high pass filter;

a notch filter; and

a band pass filter.

9. A touch display as claimed in claim 1 further including:

means for controlling said light sources; and

means for taking and processing an image taken in a non lighted ambient light state and in a lighted state;

wherein said means for processing said outputs subtracts the ambient state from the lighted state before detecting the level of light.

25. A touch display as claimed in claim 1 wherein said cameras are area scan cameras, said camera output including information on area scanned and said processor using said information in determining the location of said object.

10. A touch display comprising:

a screen for a user to touch and view an image on or through;

light sources at one or more edges in front of said screen, said light sources directing light across the surface of said screen;

at least two cameras having outputs located at the periphery of said screen, said cameras located so as not to receive direct light from said light sources, each said camera imaging said surface in front of said screen, said output including a mirrored image;

means for processing said outputs to detect level of reflected light and the level of light from said mirror image; and

a processor receiving the processed outputs of said cameras, said processor employing triangulation techniques and said processed outputs to determine whether the processed outputs indicate the presence of an object proximate to said screen and if so the location of said object.

11. A touch display as claimed in claim 10 wherein said processed output indicates the relative bearing of a presumed object location relative to said camera and the distance of said object from said screen.

12. A touch display as claimed in claim 10 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

13. A touch display as claimed in claim 10 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

14. A touch display as claimed in claim 10 wherein said processor determines the location of said object as a planar screen co-ordinate.

15. A touch display as claimed in claim 10 wherein said cameras are area scan cameras, said camera output including information on area scanned and said processor using said information in determining the location of said object.

16. A touch display as claimed in claim 10 further including:

means for modulating said light from said light sources to provide a frequency band within the imageable range of said cameras; and

means for excluding image data outside said frequency band.

17. A touch display as claimed in claim 16 wherein said means for processing said outputs includes said means for excluding image data outside said frequency band and said means for excluding image data outside said frequency includes filtering.

18. A touch display as claimed in claim 17 wherein filtering includes applying a filter selected from the group consisting of:

a comb filter;

a high pass filter;

a notch filter; and

a band pass filter.

19. A touch display as claimed in claim 10 further including:

means for controlling said light sources; and

means for taking and processing an image taken in a non lighted ambient light state and in a lighted state;

wherein said means for processing said outputs subtracts the ambient state from the lighted state before detecting the level of light.

20. A touch display comprising:

a screen for a user to touch and view an image on or through;

light sources at one or more edges behind said screen, said light sources directing light across the surface of said screen;

at least two cameras having outputs located at the periphery of said screen, said cameras located so as not to receive direct light from said light sources, each said camera imaging said surface in front of said screen, said output including a mirror image;

means for processing said outputs to detect level of reflected light and the level of light from said mirror image; and

a processor receiving the processed outputs of said cameras, said processor employing triangulation techniques and said processed outputs to determine whether the processed outputs indicate the presence of an object proximate to said screen and if so the location of said object.

21. A touch display as claimed in claim 20 wherein said processed output indicates the relative bearing of a presumed object location relative to said camera and the distance of said object from said screen.

22. A touch display as claimed in claim 20 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

23. A touch display as claimed in claim 20 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

24. A touch display as claimed in claim 20 wherein said processor determines the location of said object as a planar screen co-ordinate.

26. A touch display as claimed in claim 20 wherein said light sources are behind said screen arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen.

27. A touch display as claimed in claim 20 further including:

means for modulating said light from said light sources to provide a frequency band within the imageable range of said cameras; and

means for excluding image data outside said frequency band.

28. A touch display as claimed in claim 27 wherein said means for processing said outputs includes said means for excluding image data outside said frequency band and said means for excluding image data outside said frequency includes filtering.

29. A touch display as claimed in claim 28 wherein filtering includes applying a filter selected from the group consisting of:

a comb filter;

a high pass filter;

a notch filter; and

a band pass filter.

30. A touch display as claimed in claim 20 further including:

means for controlling said light sources; and

means for taking and processing an image taken in a non lighted ambient light state and in a lighted state;

wherein said means for processing said outputs subtracts the ambient state from the lighted state before detecting the level of light.

31. A touch display comprising:

a screen for a user to touch and view an image on or through;

light sources at one or more edges of said screen, said light sources directing light across the surface of said screen;

means for controlling the operation of sections of said light sources independent of other sections of said light sources;

at least two cameras having outputs, each said camera located at the periphery of said screen to image the space in front of said screen, said output including a scanned image;

means for processing said outputs to detect the level of light, said light including;

direct light from said light sources, and/or

reflected light from said light sources;

a processor receiving the processed outputs of said cameras, said processor employing triangulation techniques and said processed outputs to determine whether the processed outputs indicate the presence of an object proximate to said screen and if so the location of said object.

32. A touch display as claimed in claim 31 wherein said processed output indicates the relative bearing of a presumed object location relative to said camera and the distance of said object from said screen.

33. A touch display as claimed in claim 31 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

34. A touch display as claimed in claim 31 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

35. A touch display as claimed in claim 31 wherein said cameras are line scan cameras, said camera output including information on line scanned and said processor using said information in determining the location of said object.

36. A touch display as claimed in claim 31 wherein said processor determines the location of said object as a planar screen co-ordinate.

37. A touch display as claimed in claim 31 wherein said light sources are behind said screen arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen.

38. A touch display as claimed in claim 31 wherein said light sources are Light Emitting Diodes (LEDs).

40. A touch display as claimed in claim 38 wherein the means for controlling sections of said light source comprises wiring said sections in antiphase and driving using a bridge drive.

41. A touch display as claimed in claim 38 wherein the means for controlling sections of said light source comprises using a diagonal bridge drive.

42. A touch display as claimed in claim 38 wherein the means for controlling sections of said light source comprises using a shift register for each section to be controlled.

43. A touch display as claimed in claim 38 wherein said means for taking and processing images includes controlling sections of said light sources and each said camera and said means for processing said outputs includes processing information on whether a said section is lighted or not.

44. A touch display as claimed in claim 43 wherein some sections are lighted and others are not when an image is taken.

39. A touch display as claimed in 38 wherein means for controlling the operation of sections of said light source includes means for independently controlling the effective intensity of said light source.

45. A method of receiving user inputs in reference to an image including the steps of:

providing a screen for a user to touch and view an image on or through;

providing light sources at one or more edges of said screen, said light sources directing light across the surface of said screen;

modulating said light from said light sources at a frequency within an imageable range of said cameras;

providing at least two cameras having outputs, each said camera located at the periphery of said screen to image the space in front of said screen, said output including a scanned image;

processing said outputs to detect the level of light, said light including;

direct light from said light sources, and/or

reflected light from said light sources;

processing said outputs to exclude image data outside said modulation frequency;

processing the processed outputs of said cameras, using triangulation techniques to obtain the location of said object.

46. A method of receiving user inputs in reference to an image as claimed in claim 45 wherein said processed output indicates the relative bearing of a presumed object location relative to a said camera.

47. A method of receiving user inputs in reference to an image as claimed in claim 45 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

48. A method of receiving user inputs in reference to an image as claimed in claim 45 wherein said location is a planar screen co-ordinate.

49. A method of receiving user inputs in reference to an image as claimed in claim 45 wherein said light sources are behind said screen and arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen.

50. A method of receiving user inputs in reference to an image as claimed in claim 45 wherein said cameras are line scan cameras, said camera output including information on line scanned and said processor using said information in determining the location of said object.

51. A method of receiving user inputs in reference to an image as claimed in claim 45 wherein the step of processing said outputs includes the steps of excluding image data outside said frequency band and said step of excluding image data outside said frequency includes filtering.

52. A method of receiving user inputs in reference to an image as claimed in claim 51 wherein filtering includes the step of applying a filter selected from the group consisting of:

a comb filter;

a high pass filter;

a notch filter; and

a band pass filter.

53. A method of receiving user inputs in reference to an image as claimed in claim 45 further including the steps of:

controlling said light sources; and

taking and processing an image taken in a non lighted ambient light state and in a lighted state;

wherein said step of processing said outputs subtracts the ambient state from the lighted state before detecting the level of light.

54. A method of receiving user inputs in reference to an image including the steps of:

providing a screen for a user to touch and view an image on or through;

providing light sources at one or more edges behind said screen, said light sources directing light across the surface of said screen;

controlling the operation of sections of said light sources independent of other sections of said light sources;

providing at least two cameras having outputs, each said camera located at the periphery of said screen to image the space in front of said screen, said output including a scanned image;

processing said outputs to detect the level of light, said light including;

direct light from said light sources, and/or

reflected light from said light sources;

processing the processed outputs of said cameras, using triangulation techniques to obtain the location of said object.

55. A method of receiving user inputs in reference to an image as claimed in claim 54 wherein said processed output indicates the relative bearing of a presumed object location relative to a said camera.

56. A method of receiving user inputs in reference to an image as claimed in claim 54 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

57. A method of receiving user inputs in reference to an image as claimed in claim 54 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

58. A method of receiving user inputs in reference to an image as claimed in claim 54 wherein said cameras are line scan cameras, said camera output including information on line scanned and said processor using said information in determining location of said object.

59. A method of receiving user inputs in reference to an image as claimed in claim 54 wherein said location is a planar screen co-ordinate.

60. A method of receiving user inputs in reference to an image as claimed in claim 54 wherein said light sources are behind said screen and arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen.

61. A method of receiving user inputs in reference to an image as claimed in claim 54 wherein said light sources are LEDs and said touch display includes means for controlling the operation of sections of said light source independent of other sections of said light source.

62. A method of receiving user inputs in reference to an image as claimed in claim 61 wherein the step of controlling the operation of sections of said light source includes independently controlling the effective intensity of said light source.

63. A method of receiving user inputs in reference to an image as claimed in claim 61 wherein the step of controlling sections of said light source comprises wiring said sections in antiphase and driving using a bridge drive.

64. A method of receiving user inputs in reference to an image as claimed in claim 61 wherein the step of controlling sections of said light source comprises using a diagonal bridge drive.

65. A method of receiving user inputs in reference to an image as claimed in claim 61 wherein the step of controlling sections of said light source comprises using a shift register for each section to be controlled.

66. A method of receiving user inputs in reference to an image as claimed in claim 61 wherein the step of taking and processing images includes controlling sections of said light sources and each said camera and said step of processing said outputs includes processing information on whether a said section is lighted or not.

67. A method of receiving user inputs in reference to an image as claimed in claim 66 wherein some sections are lighted and others are not when an image is taken.

68. A method of receiving user inputs in reference to an image including the steps of:

providing a screen for a user to touch and view an image on or through;

providing light sources at one or more edges behind said screen, said light sources directing light across the surface of said screen;

providing at least two cameras having outputs located at the periphery of said screen, said cameras located so as not to receive direct light from said light sources, each said camera imaging said surface in front of said screen, said output including a mirror image;

processing said outputs to detect the level of reflected light and the level of light from said mirror image; and

processing the processed outputs of said cameras, employing triangulation techniques and said processed outputs to determine whether the processed outputs indicate the presence of an object proximate to said screen and if so the location of said object.

69. A method of receiving user inputs in reference to an image as claimed in claim 68 wherein said processed output indicates the relative bearing of a presumed object location relative to said camera and the distance of said object from said screen.

70. A method of receiving user inputs in reference to an image as claimed in claim 68 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

71. A method of receiving user inputs in reference to an image as claimed in claim 68 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

72. A method of receiving user inputs in reference to an image as claimed in claim 68 wherein said processor determines location of said object as a planar screen co-ordinate.

73. A method of receiving user inputs in reference to an image as claimed in claim 68 wherein said cameras are area scan cameras, said camera output including information on area scanned and said processor using said information in determining the location of said object.

74. A touch display as claimed in claim 68 wherein said light sources are behind said screen arranged to project light through said screen and said display includes at each edge having a light source, light deflectors in front of said screen, directing light emitted from said light sources across the surface of said screen.

75. A method of receiving user inputs in reference to an image as claimed in claim 68 further including:

means for modulating said light from said light sources to provide a frequency band within the imageable range of said cameras; and

means for excluding image data outside said frequency band.

76. A method of receiving user inputs in reference to an image as claimed in claim 75 wherein said means for processing said outputs includes said means for excluding image data outside said frequency band and said means for excluding image data outside said frequency includes filtering.

77. A method of receiving user inputs in reference to an image as claimed in claim 76 wherein filtering includes applying a filter selected from the group consisting of:

a comb filter;

a high pass filter;

a notch filter; and

a band pass filter.

78. A method of receiving user inputs in reference to an image as claimed in claim 68 further including:

means for controlling said light sources; and

means for taking and processing an image taken in a non lighted ambient light state and in a lighted state;

wherein said means for processing said outputs subtracts the ambient state from the lighted state before detecting the level of light.

79. A method of receiving user inputs in reference to an image including the steps of:

providing a screen for a user to touch and view an image on or through;

providing light sources at one or more edges in front of said screen, said light sources directing light across the surface of said screen;

providing at least two cameras having outputs, said cameras located so as not to receive direct light from said light sources, each said camera imaging said surface in front of said screen, said output including a mirror image;

means for processing outputs to detect the level of reflected light and the level of light from said mirror image; and

processing the processed outputs of said cameras, using triangulation techniques to obtain the location of said object.

80. A method of receiving user inputs in reference to an image as claimed in claim 79 wherein said processed output indicates the relative bearing of a presumed object location relative to said camera and the distance of said object from said screen.

81. A method of receiving user inputs in reference to an image as claimed in claim 79 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

82. A method of receiving user inputs in reference to an image as claimed in claim 79 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

83. A method of receiving user inputs in reference to an image as claimed in claim 79 wherein said processor determines the location of said object as a planar screen co-ordinate.

84. A method of receiving user inputs in reference to an image as claimed in claim 79 wherein said cameras are area scan cameras, said camera output including information on area scanned and said processor using said information in determining the location of said object.

85. A method of receiving user inputs in reference to an image as claimed in claim 79 further including:

means for modulating said light from said light sources to provide a frequency band within the imageable range of said cameras; and

means for excluding image data outside said frequency band.

86. A method of receiving user inputs in reference to an image as claimed in claim 85 wherein said means for processing said outputs includes said means for excluding image data outside said frequency band and said means for excluding image data outside said frequency includes filtering.

87. A method of receiving user inputs in reference to an image as claimed in claim 86 wherein filtering includes applying a filter selected from the group consisting of:

a comb filter;

a high pass filter;

a notch filter; and

a band pass filter.

88. A method of receiving user inputs in reference to an image as claimed in claim 79 further including:

means for controlling said light sources; and

means for taking and processing an image taken in a non lighted ambient light state and in a lighted state;

wherein said means for processing said outputs subtracts the ambient state from the lighted state before detecting the level of light.