Touch-sensitive display with optical sensor and method

1. An electronic device comprising:

a touch-sensitive display having a top surface, a bottom surface, and a side reflective surface; and

an optical device positioned to emit an optical signal at the side reflective surface of the touch-sensitive display and configured to detect a reflection of the optical signal from the side reflective surface of the touch-sensitive display, and detect a force that results in depression of the top surface based on a change to the optical signal due to the reflection, wherein the optical signal and the reflection have a same wavelength when a force is applied to the top surface and when a force is not applied to the top surface, and a distance between the side reflective surface of the touch-sensitive display and the optical device is substantially equal to a multiple of the same wavelength when a force is not applied to the top surface.

2. The electronic device of claim 1 , wherein the optical device comprises an optical receiver and an optical emitter.

3. The electronic device of claim 1 , wherein the change comprises a change in the distance between the back surface of the touch-sensitive display and the optical device.

4. The electronic device of claim 1 , wherein the sensor comprises a plurality of optical receivers.

5. The electronic device of claim 1 , wherein the sensor detects a change in the reflection due to bending of the touch-sensitive display resulting from the force.

6. The electronic device of claim 1 , wherein the optical device comprises a first optical receiver that receives a first reflection from a first back surface of the touch-sensitive display and a second optical receiver that receives a second reflection from a second back surface of the touch-sensitive display.

7. The electronic device of claim 1 , wherein the touch-sensitive display is depressible.

8. The electronic device of claim 1 , wherein the optical device is disposed near a back surface of the touch-sensitive display.

9. The electronic device of claim 1 , wherein the reflection has a first characteristic when the force does not meet a threshold, and wherein the reflection has a second characteristic when the force meets the threshold.

10. The electronic device of claim 9 , wherein the first characteristic is a first amplitude and the second characteristic is a second amplitude that is less than the first amplitude.

11. The electronic device of claim 1 , wherein at least one of: (a) a reflective coating has been applied to the back surface to cause the optical signal to be reflected or (b) the back surface of the touch-sensitive display has been polished to cause the optical signal to be reflected.

12. An electronic device comprising:

a touch-sensitive display having a top surface, a bottom surface, and a side reflective surface;

a force sensor operable with the touch-sensitive display to detect a force exerted on the top surface and optical signals reflected from the side reflective surface of the touch-sensitive display, wherein the force sensor comprises an optical device that receives a reflection of an optical signal, wherein the reflection is affected by the force;

an optical emitter arranged to provide optical signals from which the reflection results; and

a processor configured to receive signals from the optical device and evaluate the signals to detect a variation in the optical signal after the reflection from the back surface of the touch-sensitive display, wherein the optical signal and the reflection have a same wavelength when a force is applied to the top surface and when a force is not applied to the top surface.

13. The electronic device of claim 12 , wherein the optical device and the optical emitter are integrated into a single component.

14. The electronic device of claim 12 , further configured to provide an indication of selection of a feature displayed on the touch-sensitive display when the variation meet a threshold.

15. A method comprising:

emitting an optical signal toward a side reflective surface of a touch-sensitive display, the touch-sensitive display having a top surface, a bottom surface, and the side reflective surface;

receiving a reflection of the optical signal reflected from the side reflective surface of the touch-sensitive display;

detecting a change in the optical signal due to the reflection, wherein the change is caused by a force exerted on the top surface that increases a distance between the touch-sensitive display and an optical detector, and the optical signal and the reflection have a same wavelength when a force is applied to the top surface and when a force is not applied to the top surface; and

providing an indication of the force when the change is detected.

16. The method of claim 15 , further comprising comparing the change in the optical signal to a threshold, wherein the indication is provided when the change exceeds the threshold.