Touch-sensitive device

• US 9,342,187 B2
• Filed: 01/12/2009
• Issued: 05/17/2016
• Est. Priority Date: 01/11/2008
• Status: Active Grant

• Current Assignee: O-Net WaveTouch Limited
• Original Assignee: O-Net WaveTouch Limited
• Inventors: Pedersen, Henrik Chresten, Jakobsen, Michael Linde, Hanson, Vagn Steen Gruner
• Primary Examiner(s): Simpson, Lixi C
• Assistant Examiner(s): Pham Lu, Ngan T
• Application Number:
  US12/812,538
• Publication Number:
  US 20110025620A1
• Time in Patent Office: 2,682 Days
• Field of Search: 345173-176
• US Class Current: 1/1
• 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 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

The present invention relates to an optical touch-sensitive device and a method of determining a position and determining a position change of an object contacting an optical touch sensitive device. In particular, the present invention relates to an optical touch pad and a method of determining a position and determining a position change of an object contacting an optical touch pad. A touch-sensitive device, according to the present invention may comprise a light source, a touch-sensitive waveguide, a detector array, and a first light redirecting member, wherein at least a part of the light propagating towards a specific point of the detector array is prevented from being incident upon the specific point of the detector array when an object contacts a touch-sensitive surface of the touch-sensitive waveguide at a corresponding specific contact point.

Claims

1. A touch-sensitive device, comprising:

a light source for emitting light into a touch-sensitive waveguide,

the touch-sensitive waveguide comprising side parts and a touch-sensitive surface extending between the side parts of the touch-sensitive waveguide, the touch-sensitive waveguide being configured for guiding light from the light source towards the touch-sensitive surface of the touch-sensitive waveguide in such a way that at least part of the guided light may be disturbed by an object at a contact point where the object contacts the touch-sensitive surface,

a detector array configured for detecting intensity distribution of light having propagated from the light source through the touch-sensitive waveguide for position encoding the contact point between the object and the touch-sensitive surface, and

a first light redirecting member included in at least one of the side parts of the touch-sensitive waveguide, the first light redirecting member being configured for

redirecting light having propagated from the light source through the touch-sensitive waveguide and to the first light redirecting member towards the detector array, such that the redirection of light involves changing the direction of propagation in a plane parallel to the touch-sensitive surface after having propagated under the touch-sensitive surface inside the touch-sensitive waveguide,

wherein at least a part of the light propagating towards a specific point of the detector array is prevented from being incident upon the specific point of the detector array when the object contacts the touch-sensitive surface at a corresponding specific contact point.

2. A touch-sensitive device according to claim 1, wherein the touch-sensitive waveguide is a planar waveguide.

3. A touch-sensitive device according to claim 1, wherein the touch-sensitive waveguide furthermore is configured for guiding light that has been redirected and converged towards the detector array by the first light redirecting member towards the detector array.

4. A touch-sensitive device according to claim 1, comprising a first transmitter waveguide configured for guiding light that has been redirected and converged towards the detector array by the first light redirecting member towards the detector array.

5. A touch-sensitive device according to claim 4, wherein the first transmitter waveguide is a planar waveguide.

6. A touch-sensitive device according to claim 4, wherein the touch-sensitive waveguide and the first transmitter waveguide are stacked.

7. A touch-sensitive device according to claim 1, comprising a second light redirecting member configured for redirecting incident light from the light source through the touch-sensitive waveguide which is configured for guiding at least a part of the redirected light towards the first light redirecting member which is configured for redirecting and converging at least a part of the incident light towards the detector array.

8. A touch-sensitive device according to claim 7, wherein the touch-sensitive waveguide furthermore is configured for guiding light from the light source towards the second light redirecting member which is configured for redirecting at least a part of the incident light back through the touch-sensitive waveguide which is configured for guiding at least a part of the redirected light towards the first light redirecting member which is configured for redirecting and converging at least a part of the incident light towards the detector array.

9. A touch-sensitive device according to claim 7, wherein the first transmitter waveguide furthermore is configured for guiding light from the light source towards the second light redirecting member which is configured for redirecting at least a part of the incident light through the touch-sensitive waveguide which is configured for guiding at least a part of the redirected light towards the first light redirecting member which is configured for redirecting and converging at least a part of the incident light towards the detector array.

10. A touch-sensitive device according to claim 7, comprising a second transmitter waveguide configured for guiding light from the light source towards the second light redirecting member which is configured for redirecting at least a part of the incident light through the touch-sensitive waveguide which is configured for guiding at least a part of the redirected light towards the first light redirecting member which is configured for redirecting and converging at least a part of the incident light towards the detector array.

11. A touch-sensitive device according to claim 10, wherein the second transmitter waveguide is a planar waveguide.

12. A touch-sensitive device according to claim 10, wherein the touch-sensitive waveguide and the second transmitter waveguide are stacked.

13. A touch-sensitive device according to claim 1, wherein light emitted by the light source is modulated.

14. A touch-sensitive device according to claim 1, comprising a signal processor adapted for position encoding the contact point between the object and the touch-sensitive waveguide.

15. A touch-sensitive device according to claim 14, wherein the signal processor furthermore is adapted for calculating a contact area between the object and the touch-sensitive waveguide.

16. A touch-sensitive device according to claim 14, wherein the signal processor furthermore is adapted for calculating a velocity between the object and the touch-sensitive waveguide.

17. A touch-sensitive device according to claim 14, wherein the signal processor furthermore is adapted for calculating an acceleration between the object and the touch-sensitive waveguide.

18. A touch-sensitive device according to claim 1, wherein at least a part of the touch-sensitive surface comprises an optical coating.

19. A touch-sensitive device according to claim 18, wherein the optical coating is an anti-reflective coating.

20. A touch-sensitive device according to claim 1, wherein light from the light source, which light is guided by the touch-sensitive waveguide, has an angle of incidence relative to the touch-sensitive surface, such that the light is not disturbed by water contacting the touch-sensitive surface.

21. A touch-sensitive device according to claim 1, wherein light from the light source, which light is guided by the touch-sensitive waveguide, has an angle of incidence relative to the touch-sensitive surface, such that the light is not disturbed by a material contacting the touch-sensitive surface which material has a lower refractive index than the object, such as approximately five percent lower.

22. A touch-sensitive device according to claim 1, wherein the first light redirecting member comprises at least one reflecting part.

23. A touch-sensitive device according to claim 1, wherein the first light redirecting member comprises at least one facetted element.

24. A touch-sensitive device according to claim 1, wherein the first light redirecting member comprises at least one concave element.

25. A touch-sensitive device according to claim 1, wherein the first light redirecting member comprises at least one bevelled element.

26. A touch-sensitive device according to claim 23, wherein the at least one element is a mirror.

27. A touch-sensitive device according to claim 1, wherein the first light redirecting member comprises at least one diffraction grating.

28. A touch-sensitive device according to claim 1, wherein a waveguide comprises a layer having a lower refractive index than a core of the waveguide.

29. A touch-sensitive device according to claim 28, wherein the layer comprises a fluoropolymer.

30. A touch-sensitive device according to claim 1, comprising at least one microstructure configured for redirecting light through the touch-sensitive surface for displaying information to a user.

31. A touch-sensitive device according to claim 30, wherein the at least one microstructure is embedded in a waveguide situated behind the touch-sensitive waveguide, where light redirected by the at least one microstructure is propagating through the touch-sensitive waveguide and through the touch-sensitive surface for displaying information to the user.

32. A touch-sensitive device according to claim 1, wherein the first light redirecting member comprises a reflective surface having an angle within 60°

-89°

relative to the touch-sensitive surface.

33. A touch-sensitive device according to claim 4, wherein the first transmitter waveguide includes a number of substantially one-dimensional cores for guiding light along a longitudinal extension of each of the one-dimensional cores.

34. A touch-sensitive device according to claim 1, wherein the touch-sensitive waveguide has a substantially planar geometry with embedded grooves or channels for guiding light.

35. A touch-sensitive device according to claim 34, wherein at least some of the embedded grooves or channels for guiding light are intersecting.

36. A touch-sensitive device according to claim 35, wherein the intersecting grooves or channels for guiding light are substantially orthogonal.

38. A touch-sensitive device according to claim 32, wherein the first light redirecting member comprises a reflective surface having an angle within 70°

-86°

relative to the touch-sensitive surface.

39. A touch-sensitive device according to claim 38, wherein the first light redirecting member comprises a reflective surface having an angle around 81°

relative to the touch-sensitive surface.

37. A method of position encoding an object contacting a touch-sensitive surface, the method comprising:

emitting light from a light source into a touch-sensitive waveguide comprising side parts and the touch-sensitive surface extending between the side parts of the touch-sensitive waveguide,

guiding light from the light source towards the touch-sensitive surface of the touch-sensitive waveguide, using the touch-sensitive waveguide, in such a way that at least part of the guided light may be disturbed by the object at a contact point where the object contacts the touch-sensitive surface,

detecting, using a detector array, intensity distribution of light having propagated from the light source through the touch-sensitive waveguide for position encoding the contact point between the object and the touch-sensitive surface, and

redirecting light having propagated from the light source through the touch-sensitive waveguide and to the first light redirecting member included in the at least one of the side parts of the touch-sensitive waveguide towards the detector array using the first light redirecting member, such that the redirected light changes the direction of propagation in a plane parallel to the touch-sensitive surface after having propagated under the touch-sensitive surface inside the touch-sensitive waveguide wherein

at least a part of the light propagating towards a specific point of the detector array is prevented from being incident upon the specific point of the detector array when the object contacts the touch-sensitive surface at a corresponding specific contact point and with a redirecting member configured so that at least part of the guided light after having been redirected by a redirecting member changes between being prevented from being disturbed and being disturbed by the object at a contact point.