Touch screen signal processing

• US 8,289,299 B2
• Filed: 10/16/2009
• Issued: 10/16/2012
• 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
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): Zhou, Hong
• Application Number:
  US12/580,409
• Publication Number:
  US 20100097353A1
• Time in Patent Office: 1,096 Days
• Field of Search: 345173-179, 178 1801- 1809, 178/18.11, 178/20.01
• 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;

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

at least two cameras located at the periphery of said screen, said at least two cameras located so as not to receive direct light from said plurality of light sources, each of said at least two cameras configured to generate an output by imaging said surface in front of said screen, said output including a mirrored image generated from each of said at least two cameras detecting light reflected from the surface of said screen; and

a processor configured to;

generate processed outputs by processing said outputs to detect a level of reflected light and a level of light from said minor image; and

employ triangulation techniques using said processed outputs to determine the presence of an object proximate to said screen and a 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 and the distance of said object from said screen.

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 processed output indicates that said object has touched said screen when said object and said presumed object coincide.

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

6. A touch display as claimed in claim 1 wherein said at least two 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.

7. A touch display as claimed in claim 1:

wherein the processor is further configured to;

cause said plurality of light sources to modulate said light to provide a frequency band within the imageable range of said at least two cameras; and

exclude image data outside said frequency band.

8. A touch display as claimed in claim 7 wherein the processor is further configured to exclude image data outside said frequency band and to exclude image data outside said frequency includes filtering.

9. A touch display as claimed in claim 8 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.

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

control circuitry configured to control said plurality of 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 processor is configured to subtract the ambient state from the lighted state before detecting the level of light.

25. A method of receiving user inputs in reference to an image as claimed in claim 2 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

11. A touch display comprising:

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

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

at least two cameras located at the periphery of said screen, said at least two cameras located so as not to receive direct light from said plurality of light sources, each of said at least two cameras configured to generate an output by imaging said surface in front of said screen, said output including a mirror image generated from each of said at least two cameras detecting light reflected from the surface of said screen; and

a processor configured to;

generate processed outputs by processing said outputs to detect a level of reflected light and a level of light from said minor image; and

employ triangulation techniques using said processed outputs to determine the presence of an object proximate to said screen and a location of said object.

12. A touch display as claimed in claim 11 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.

13. A touch display as claimed in claim 11 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

14. A touch display as claimed in claim 11 wherein said processed output indicates that said object has touched said screen when said object and said presumed object coincide.

15. A touch display as claimed in claim 11 wherein said processor determines the location of said object as a planar screen co-ordinate.

16. A touch display as claimed in claim 11 wherein said at least two 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.

17. A touch display as claimed in claim 11 wherein said plurality of 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 plurality of light sources across the surface of said screen.

18. A touch display as claimed in claim 11, wherein the processor is further configured to:

cause said plurality of light sources to modulate said light to provide a frequency band within the imageable range of said at least two cameras; and

exclude image data outside said frequency band.

19. A touch display as claimed in claim 18 wherein the processor is further configured to exclude image data outside said frequency band and to exclude image data outside said frequency includes filtering.

20. A touch display as claimed in claim 19 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.

21. A touch display as claimed in claim 11 further including:

control circuitry configured to control said plurality of light sources; and

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

wherein the processor is further configured to subtract the ambient state from the lighted state before detecting the level of light.

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

providing at least two cameras located at the periphery of said screen, said at least two cameras located so as not to receive direct light from said plurality of light sources, each of said at least two cameras configured to generate an output by imaging said surface in front of said screen, said output including a mirror image generated from each of said at least two cameras detecting light reflected from the surface of said screen;

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

processing the processed outputs of said at least two cameras by employing triangulation techniques using said processed outputs to determine the presence of an object proximate to said screen a location of said object.

23. A method of receiving user inputs in reference to an image as claimed in claim 22 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.

24. A method of receiving user inputs in reference to an image as claimed in claim 22 wherein said processed output indicates the relative bearing of a presumed object location relative to the centre of the lens of said camera.

26. A method of receiving user inputs in reference to an image as claimed in claim 22 wherein said processor determines location of said object as a planar screen co-ordinate.

27. A method of receiving user inputs in reference to an image as claimed in claim 22 wherein said at least two 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.

28. A touch display as claimed in claim 22 wherein said plurality of 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 plurality of light sources across the surface of said screen.

29. A method of receiving user inputs in reference to an image as claimed in claim 22 further including:

modulating said light from said plurality of light sources to provide a frequency band within the imageable range of said at least two cameras; and

excluding image data outside said frequency band.

30. A method of receiving user inputs in reference to an image as claimed in claim 29 wherein said processing said outputs includes excluding image data outside said frequency band and excluding image data outside said frequency includes filtering.

31. A method of receiving user inputs in reference to an image as claimed in claim 30 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.

32. A method of receiving user inputs in reference to an image as claimed in claim 22 further including:

controlling said plurality of light sources; and

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

wherein processing said outputs comprises subtracting the ambient state from the lighted state before detecting the level of light.