Thin couplers and reflectors for sensing waveguides
An optical touch-sensitive device is able to determine the locations of multiple simultaneous touch events. The optical touch-sensitive device can include an optical waveguide, an emitter, and an emitter coupler. The emitter produces optical beams, and the emitter coupler is on a surface of the waveguide and is configured to direct at least some of the optical beams to propagate via total internal reflection (TIR) through the waveguide as coupled optical beams. Touches on the top surface of the waveguide disturb the coupled optical beams, and the touch-sensitive device determines touch events based on the disturbances.
1. An optical touch-sensitive device comprising:
an optical waveguide;
one or more emitters emitting optical beams that propagate via total internal reflection (TIR) in the waveguide, wherein touches on a surface of the waveguide disturb the optical beams, the touch-sensitive device determining touch events based on the disturbances; and
an optical reflector on a surface of the waveguide, the optical reflector redirecting optical beams propagating in the waveguide, wherein incident optical beams propagate through the waveguide at an initial elevation angle and redirected optical beams propagate through the waveguide at a modified elevation angle, the optical reflector including reflective structures, a first one of the reflective structures comprising:
a first surface oriented to redirect optical beams incident at the initial elevation angle at the modified elevation angle as redirected optical beams; and
a second surface oriented to redirect a subset of the redirected optical beams at an intermediate elevation angle towards a second one of the reflective structures.
2. The optical touch-sensitive device of claim 1 , wherein the intermediate elevation angle is substantially equal to the negative of the initial elevation angle.
3. The optical touch-sensitive device of claim 1 , wherein the beams propagating at the intermediate elevation angle towards the second reflecting structure are redirected by a first surface of the second reflecting structure at the modified elevation angle.
4. The optical touch-sensitive device of claim 1 , wherein at least one of the reflective structures is metalized.
5. The optical touch-sensitive device of claim 1 , wherein the optical reflector is an integrated portion of the waveguide.
6. The optical touch-sensitive device of claim 1 , wherein the optical reflector is an integrated portion of a thin film attached to a surface of the waveguide.
7. The optical touch-sensitive device of claim 6 , wherein a thickness of the film is less than or equal to 500 micrometers.
8. The optical touch-sensitive device of claim 1 , wherein the optical reflector height is less than or equal to 500 micrometers.
9. The optical touch-sensitive device of claim 1 , wherein the modified elevation angle is substantially equal to the initial elevation angle.
10. The optical touch-sensitive device of claim 1 , wherein the modified elevation angle is smaller than the initial elevation angle.
11. The optical touch-sensitive device of claim 10 , wherein beams propagating at the modified elevation angle are less sensitive to touches than beams propagating at the initial elevation angle.
12. The optical touch-sensitive device of claim 1 , wherein the modified elevation angle is larger than the initial elevation angle.
13. The optical touch-sensitive device of claim 12 , wherein beams propagating at the modified elevation angle are more sensitive to touches than beams propagating at the initial elevation angle.
14. The optical touch-sensitive device of claim 1 , wherein the waveguide includes at least two layers, the layers having different indices of refraction.
15. The optical touch-sensitive device of claim 14 , wherein optical beams propagating at the initial elevation angle propagate through both layers and optical beams propagating at the modified elevation angle propagate through only one of the layers.
16. The optical touch-sensitive device of claim 14 , wherein optical beams propagating at the modified elevation angle propagate through both layers and optical beams propagating at the initial elevation angle propagate through only one of the layers.
17. The optical touch-sensitive device of claim 1 , wherein the optical reflector redirects some of the optical beams towards another optical reflector.
18. The optical touch-sensitive device of claim 1 , wherein the optical reflector redirects some of the optical beams towards one or more detectors or detector couplers receiving optical beams propagating in the waveguide.
19. The optical touch-sensitive device of claim 1 , wherein the optical reflector changes a beam footprint of the optical beams.
20. The optical touch-sensitive device of claim 1 , wherein the reflector is placed at a periphery of a surface of the waveguide.