Photonic touch screen apparatus and method of use

• US 20060227120A1
• Filed: 03/28/2006
• Published: 10/12/2006
• Est. Priority Date: 03/28/2005
• Status: Active Grant

• Current Assignee: Adam Eikman
• Original Assignee: Adam Eikman
• Inventors: Eikman, Adam
• Granted Patent: US 7,705,835 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386

Abstract

A method and an apparatus are disclosed for determining the position of a stimulus in two axes on a surface. The apparatus includes: a transparent waveguide panel with parallel top and a bottom surfaces and at least one edge that is perpendicular to the top and bottom surfaces; a light source that is directed to the edge of the waveguide to produce light that is contained within the waveguide by Total Internal Reflection and a light detector for producing an electrical signal that is representative of an image of the light emitted by the waveguide. The light detector is positioned to receive light emitted by Frustrated Total Internal Reflection from the transparent wave guide when a physical stimulus is placed in contact with the top surface of the transparent waveguide.

Claims

1. An apparatus for determining position of a stimulus in two axes on a surface, comprising:

A transparent waveguide panel having a top and a bottom surface, which surfaces are parallel to each other, and at least one edge, which is perpendicular to said top and bottom surfaces;

a light source directed to said at least one edge wherein said light source is configured to produce light that is contained within said waveguide by Total Internal Reflection; and

a light detector for producing an electrical signal representative of an image of light received;

wherein said light detector is positioned to receive light emitted by Frustrated Total Internal Reflection from said transparent waveguide when a physical stimulus is placed in contact with said top surface of said transparent wave guide.

5. The apparatus of claim 1 wherein said light source is modulated and said light detector is tuned to receive light only of the same modulation as said light source.

6. The apparatus of claim 1 further comprising a first edge on said transparent waveguide panel having a first edge length, which first edge is perpendicular to said top and bottom surfaces;

a second edge having a second edge length, which second edge is perpendicular to said top and bottom surfaces and which is at an angle to said first edge;

wherein said light source is directed to said first edge to produce a plurality of discrete light rays that are contained within said waveguide by Total Internal Reflection and wherein each of said discrete light rays has an emission location which is along the first edge length of said first edge; and

wherein said light detector is comprised of a plurality of discrete light detecting elements distributed along the second edge length of said second edge, said light detecting elements configured to produce an electrical signal representative of light intensity emitted by Frustrated Total Internal Reflection at said second edge when a physical stimulus is placed in contact with said top surface of said transparent wave guide, each light ray detector having a light ray detection location.

7. The apparatus of claim 6 further comprising:

signal processing circuitry for associating at least one of said light ray emission locations with at least one of said light ray detection locations.

8. The apparatus of claim 7 wherein said light source is selected from the group consisting of a plurality of light emitting diodes (LEDs) and a laser.

9. The apparatus of claim 6 further comprising:

a flat panel display having a viewing side and a back side wherein

said flat panel display is directly below said bottom surface of said transparent waveguide panel, with said viewing side facing said transparent waveguide panel.

10. The apparatus of claim 6 wherein said light source is modulated with a signature, and said signature is different for each of said plurality of discrete light rays, said apparatus further comprising:

signal processing circuitry coupled to said plurality of discrete light detecting elements for demodulating said signature and determining which of said discrete light rays caused said light intensity emitted from said waveguide by Frustrated Total Internal Reflection.

11. The apparatus of claim 1, further comprising:

a first edge, having a first edge length, on said transparent waveguide panel, which first edge is perpendicular to said top and bottom surfaces;

a second edge, having a second edge length on said transparent waveguide panel, which second edge is perpendicular to said top and bottom surfaces and which is at an angle to said first edge;

wherein said light source is directed to said first edge to produce a plurality of discrete first edge light rays that are contained within said waveguide by Total Internal Reflection and wherein each of said discrete first edge light rays has a first edge emission location which is along the first edge length of said first edge;

wherein said light source is further directed to said second edge to produce a plurality of discrete second edge light rays that are contained within said waveguide by Total Internal Reflection and wherein each of said discrete second edge light rays has a second edge emission location which is along the second edge length of said second edge; and

wherein said light detector is configured to produce an electrical signal representative of light intensity emitted from said waveguide panel by Frustrated Total Internal Reflection when a physical stimulus is placed in contact with said top surface of said transparent wave guide.

12. The apparatus of claim 11, further comprising:

signal processing circuitry for determining which of said first light source rays and which of said second light source rays caused said light intensity emitted from said waveguide by Frustrated Total Internal Reflection.

13. The apparatus of claim 11 wherein said light source is selected from the group consisting of a plurality of light emitting diodes (LEDs) and a laser.

14. The apparatus of claim 11 further comprising:

a flat panel display having a viewing side and a back side wherein

said flat panel display is directly below said bottom surface of said transparent waveguide panel, with said viewing side facing said transparent waveguide panel.

15. The apparatus of claim 11 wherein:

when said light source is directed to said first edge it is modulated with a plurality of first edge signatures, and each of said first edge signatures is different for each of said plurality of discrete first edge light rays; and

when said light source directed to said second edge it is modulated with a plurality of second edge signatures, and each of said second edge signatures is different for each of said plurality of discrete second edge light rays,

said apparatus further comprising;

signal processing circuitry coupled to said light detector for demodulating said signatures and determining which of said discrete first edge and second edge light rays caused said light intensity emitted from said waveguide by Frustrated Total Internal Reflection.

2. The apparatus of claim I wherein said light detector produces a signal representative of a two dimensional image of said light emitted and wherein said light detector is positioned such that said two dimensional image is representative of either said top surface or said bottom surface.

3. The apparatus of claim 2 wherein said light detector is selected from the group consisting of a camera and a Charge Coupled Device.

4. The apparatus of claim 2 further comprising:

a flat panel display having a viewing side and a back side; and

a pressure transferring medium;

wherein

said pressure transferring medium is on top of said top surface;

said flat panel display is on top of said pressure transferring medium with said back side facing said pressure transferring medium; and

said physical stimulus is transferred through said flat panel display and said pressure transferring medium to said transparent waveguide panel.

16. A method for determining position of a stimulus in two axes on a surface of a transparent waveguide having top and bottom surfaces that are parallel to each other and a first edge that is perpendicular to said top and bottom surfaces , comprising:

directing a first light source to said first edge to produce light that is contained within said waveguide by Total Internal Reflection; and

detecting light emitted by Frustrated Total Internal Reflection (FTIR) from said transparent wave guide when a physical stimulus is placed in contact with said top surface of said transparent wave guide at a specific location on said top surface.

17. The method of claim 16, further comprising:

producing at least one signal representative of where on said waveguide said light is emitted by FTIR.

18. The method of claim 17, wherein said signal represents a two dimensional location of where on said waveguide said light is emitted by FTIR.

19. The method of claim 16 further comprising:

directing a second light source to a second edge on said transparent waveguide, which is at an angle to said first edge, wherein said first light source and said second light source produce discrete first edge light rays distributed along the length of said first edge and discrete second edge light rays distributed along the length of said second edge respectively; and

determining which discrete first edge light ray and which discrete second edge light ray caused said light emitted by FTIR.

20. A method for determining a position of a stimulus in two axes on a surface of a transparent waveguide having top and bottom surfaces that are parallel to each other and a first edge that is perpendicular to said top and bottom surfaces and a second edge that is at an angle to said first edge and that is perpendicular to said top and bottom surfaces, comprising:

directing a light source producing discrete light rays to specific emission locations along said first edge to produce discrete light rays that are contained within said waveguide by Total Internal Reflection; and

detecting, at at least one specific detection location along said second edge, light emitted by Frustrated Total Internal Reflection (FTIR) from said transparent wave guide when a physical stimulus is placed in contact with said top surface of said transparent wave guide at a specific stimulus location on said top surface;

associating a specific emission location with a specific detection location when there is a detection of light emitted by FTIR at said specific detection location to determine said specific stimulus location.