Optical elements for waveguide-based optical touch screens

1. A data input apparatus having at least one transmit element, at least one receive element and a detection device in optical communication with said receive element and adapted to detect interruption of signal light extending from said transmit element to said receive element, said interruption being associated with an input to said apparatus wherein at least one of said transmit element and said receive element includes at least one waveguide, each waveguide having a light transmitting core portion for transmission of said signal light and a non-core portion, and a discontinuance added to said non-core portion and adapted to substantially reduce the amount of stray light within said non-core portion reaching said detection device, said discontinuance being free of contact with said core portion.

2. A data input apparatus as claimed in claim 1 wherein said transmit element is coupled to a source of said signal light.

3. A data input apparatus as claimed in claim 1 wherein said discontinuance is adapted to scatter said stray light.

4. A data input apparatus as claimed in claim 3 wherein said discontinuance includes a plurality of light scattering grooves in said non-core portion.

5. A data input apparatus as claimed in claim 4 wherein said discontinuance is formed in at least a substrate of said waveguide.

6. A data input apparatus as claimed in claim 3 wherein said discontinuance includes particles and/or voids embedded in said non-core portion.

7. A data input apparatus as claimed in claim 6 wherein said discontinuance is formed in at least a substrate of said waveguide.

8. A data input apparatus as claimed in claim 1 wherein said discontinuance is adapted to absorb said stray light.

9. A data input apparatus as claimed in claim 1 wherein said discontinuance is adapted to divert said stray light.

10. A data input apparatus as claimed in claim 1 wherein said discontinuance is adapted to block said stray light from entering or leaving said non-core portion.

11. A data input apparatus as claimed in claim 10 wherein said discontinuance includes an opaque shield applied to said non-core portion.

12. A data input apparatus as claimed in claim 1 wherein said discontinuance includes a coating applied to said non-core portion.

13. A data input apparatus as claimed in claim 12 wherein said coating has a refractive index slightly higher than that of said non-core portion.

14. A data input apparatus as claimed in claim 13 wherein said coating includes a substance highly absorbing at a wavelength of said signal light.

15. A data input apparatus as claimed in claim 12 wherein said coating includes a substance highly absorbing at a wavelength of said signal light.

16. A data input apparatus as claimed in claim 1 wherein said discontinuance includes a substance with broadband absorption in the UV, visible and infrared regions of the spectrum.

17. A data input apparatus as claimed in claim 1 wherein said discontinuance includes a polymer doped with a light absorbing dye.

18. A data input apparatus as claimed in claim 1 wherein said discontinuance includes a material deposited along an edge of said waveguide.

19. A data input apparatus as claimed in claim 1 wherein said non-core portion includes at least one of an upper cladding, a lower cladding and a substrate.

20. A data input apparatus as claimed in claim 19 wherein said discontinuance is provided between a substrate and a lower cladding of said waveguide.

21. A data input apparatus as claimed in claim 1 wherein said discontinuance includes a substrate on which respective transmit/receive elements are formed, said substrate including a material that is highly absorbing at least at a wavelength of said signal light.

22. A data input apparatus as claimed in claim 21 wherein said substrate includes material that has broadband absorption in the UV, visible and IR regions of the spectrum.

23. A data input apparatus as claimed in claim 22 wherein said substrate has a refractive index slightly higher than that of said transmit/receive elements.

24. A data input apparatus as claimed in claim 21 wherein said substrate has a refractive index slightly higher than that of said transmit/receive elements.

25. A data input apparatus as claimed in claim 1 wherein said discontinuance includes a common base on which respective transmit/receive elements are mounted, said common base including a material or being coated with material that is highly absorbing at least at a wavelength of said signal light.

26. A data input apparatus as claimed in claim 25 wherein said common base includes material that has broadband absorption in the UV, visible and IR regions of the spectrum.

27. A data input apparatus as claimed in claim 26 wherein said common base has a refractive index higher than that of said non-core portion.

28. A data input apparatus as claimed in claim 25 wherein said common base has a refractive index higher than that of said non-core portion.

29. A data input apparatus as claimed in claim 1 wherein a respective transmit or receive element includes a plurality of discontinuances.

30. A method for reducing the transmission of stray light in a data input apparatus, said data input apparatus including at least one transmit element, at least one receive element and a detection device in optical communication with said receive element and adapted to detect interruption of signal light extending from said transmit element to said receive element, said interruption being associated with an input to said apparatus, wherein at least one of said transmit element and said receive element includes at least one waveguide, each waveguide having a light transmitting core portion for transmission of said signal light and a non-core portion, and wherein said method includes adding to said non-core portion a discontinuance adapted to substantially reduce the amount of stray light within said non-core portion reaching said detection device, said discontinuance being free of contact with said core portion.

31. A method as claimed in claim 30 wherein said transmit element is coupled to a source of said signal light.

32. A method as claimed in claim 30 wherein said discontinuance is adapted to scatter said stray light.

33. A method as claimed in claim 32 wherein said discontinuance includes one or more light scattering grooves in said non-core portion.

34. A method as claimed in claim 33 wherein said discontinuance is formed in at least a substrate of said waveguide.

35. A method as claimed in claim 32 wherein said discontinuance includes particles and/or voids embedded in said non-core portion.

36. A method as claimed in claim 35 wherein said discontinuance is formed in at least a substrate of said waveguide.

37. A method as claimed in claim 30 wherein said discontinuance is adapted to absorb said stray light.

38. A method as claimed in claim 30 wherein said discontinuance is adapted to divert said stray light.

39. A method as claimed in claim 30 wherein said discontinuance is adapted to block said stray light from entering or leaving said non-core portion.

40. A method as claimed in claim 39 wherein said discontinuance is provided as an opaque shield applied to said non-core portion.

41. A method as claimed in claim 30 wherein said discontinuance includes a coating applied to said non-core portion.

42. A method as claimed in claim 41 wherein said coating has a refractive index slightly higher than that of said non-core portion.

43. A method as claimed in claim 42 wherein said coating includes a substance highly absorbing at a wavelength of said signal light.

44. A method as claimed in claim 41 wherein said coating includes a substance highly absorbing at a wavelength of said signal light.

45. A method as claimed in claim 30 wherein said discontinuance includes a substance with broadband absorption in the UV, visible and IR regions of the spectrum.

46. A method as claimed in claim 30 wherein said discontinuance includes a polymer doped with a light absorbing dye.

47. A method as claimed in claim 30 wherein said discontinuance is provided along an edge of said waveguide.

48. A method as claimed in claim 30 wherein said non-core portion includes at least one of an upper cladding, a lower cladding and a substrate.

49. A method as claimed in claim 48 wherein said discontinuance is provided between a substrate and a lower cladding of said waveguide.

50. A method as claimed in claim 30 wherein said discontinuance includes a substrate on which respective transmit/receive elements are formed, said substrate including a material that is highly absorbing at least at a wavelength of said signal light.

51. A method as claimed in claim 50 wherein said substrate includes material that has broadband absorption in the UV, visible and IR regions of the spectrum.

52. A method as claimed in claim 51 wherein said substrate has a refractive index slightly higher than that of said transmit/receive elements.

53. A method as claimed in claim 50 wherein said substrate has a refractive index slightly higher than that of said transmit/receive elements.

54. A method as claimed in claim 30 wherein said discontinuance is provided as a common base on which the respective transmit/receive elements are mounted, said common base including a material or being coated with material that is highly absorbing at least at a wavelength of said signal light.

55. A method as claimed in claim 54 wherein said common base includes material that has broadband absorption in the UV, visible and IR regions of the spectrum.

56. A method as claimed in claim 55 wherein said common base has a refractive index higher than that of said non-core portion.

57. A method as claimed in claim 54 wherein said common base has a refractive index higher than that of said non-core portion.

58. A method as claimed in claim 30 wherein a respective transmit or receive element includes a plurality of discontinuances.