Elastic touch input surface
A device including an elastic layer that, when depressed by an object, causes a local indentation in the layer, the geometry of the local indentation being in accordance with a force of depression, light emitters, light detectors, a light guide between the emitters and the layer directing light beams from the emitters into the layer at an angle such that the light beams, after entering the layer, remain confined to the layer by total internal reflection, a light guide between the detectors and the layer that directs light beams exiting the layer onto the detectors, each detector having a reference output value corresponding to expected light detection when no object is touching the layer, and a processor determining the object's force of depression based on the geometry of the local indentation in the layer, as calibrated by a deviation between actual and reference output values for one of the detectors.
1. A touch input device, comprising: a housing; an elastic layer at which depression by an object causes a local indentation in the elastic layer, the geometry of the local indentation being in accordance with the object's force of depression; one or more light emitters mounted in said housing; one or more light detectors mounted in said housing; a light guide positioned between said emitters and said elastic layer, that directs light beams from said emitters into said elastic layer at an angle such that the light beams, after entering said elastic layer, remain confined to said elastic layer by total internal reflection; a light guide positioned between said detectors and said elastic layer, that directs light beams exiting said elastic layer onto said detectors, each detector having a reference output value corresponding to an expected amount of light detection when said emitters are activated and no object is touching said elastic layer; and a processor, mounted in said housing and connected to said light detectors, determining the object's force of depression based on the geometry of the local indentation in the elastic layer, as calibrated by a deviation between actual and reference output values for one of said detectors; wherein said processor further determines a depth of the local indentation.
2. The touch input device of claim 1 , wherein the deviation comprises an actual output value from a light detector that is less than the reference output value for that detector.
3. The touch input device of claim 1 , wherein the deviation comprises an actual output value from a light detector that is greater than the reference output value for that detector.
4. The touch input device of claim 1 , wherein said processor further determines a location of the local indentation.
5. The touch input device of claim 1 , wherein said elastic layer is transparent, further comprising a display mounted in said housing underneath said elastic layer.
6. The touch input device of claim 1 , wherein the deviation comprises an actual output value from a first of said light detectors that is less than the reference output value for that first detector, and an actual output value from a second of said light detectors that is greater than the reference output value for that second detector.
7. The touch input device of claim 1 , wherein said elastic layer comprises a semi-hard gel.
8. The touch input device of claim 1 , wherein said light guides are comprised of a different material than said elastic layer, and wherein said light guides and said elastic layer are manufactured by a single over-molding process.
9. A method for providing touch input to an electronic device, comprising: providing an elastic layer at which depression by an object causes a local indentation in the elastic layer, the geometry of the local indentation being in accordance with the object's force of depression; directing light beams into the elastic layer at one or more locations along edges of the elastic layer at an angle such that the light beams, after entering the elastic layer, remain confined to the elastic layer by total internal reflection, and exit the layer at exit locations along edges of the elastic layer; detecting light beams that exit the elastic layer at one or more exit locations, each exit location having a reference output value corresponding to an expected amount of light detection when no object is touching the elastic layer; and determining the object's force of depression based on the geometry of the local indentation in the elastic layer, as calibrated by a deviation between an actual detected amount of light and a corresponding reference amount of light at one of the exit locations; and determining a depth of the local indentation in the elastic layer.
10. The method of claim 9 , wherein the deviation comprises the actual detected amount of light that is less than the reference amount of light for one of the exit locations.
11. The method of claim 9 , wherein the deviation comprises the actual detected amount of light that is greater than the reference amount of light for one of the exit locations.
12. The method of claim 9 , further comprising determining a location of the local indentation in the elastic layer.
13. The method of claim 9 , wherein the elastic layer is transparent, further comprising providing a display presenting user interaction information underneath the elastic layer.
14. The method of claim 9 , wherein the deviation comprises the actual detected amount of light that is less than the reference amount of light at a first exit location, and the actual detected amount of light that is greater than the reference amount of light at a second exit location.
15. The method of claim 9 , wherein the elastic layer comprises a semi-hard gel.
16. The touch input device of claim 1 , further comprising a haptic driver, mounted in said housing and connected to said elastic layer and to said processor, generating haptic vibrations in said elastic layer at the location of the local indentation.
17. The method of claim 9 , further comprising generating haptic vibrations in the elastic layer at the location of the local indentation, in response to said determining.