Active acoustic touch location for electronic devices

1. A method of determining the location of a user touch on a display of an electronic device, the method comprising:

generating standing waves to propagate through a display on an electronic device responsive to detecting a user touch on the display;

detecting a sound of the standing waves affected by the user touch;

converting an amplitude of the detected sound into digitized signals;

computing an acoustic signature for the amplitude based on the digitized signals; and

determining a location of the user touch on the display based on the computed acoustic signature.

2. The method of claim 1 wherein generating the standing waves comprises activating first and second haptic transducers on the display to generate the standing waves.

3. The method of claim 1 wherein generating standing waves to propagate through the display comprises configuring first and second haptic transducers disposed on the display to alternate between operating in a driver mode to generate the standing waves, and a sensor mode to detect variations in the standing waves caused by the user touch.

4. The method of claim 3 wherein configuring the first and second haptic transducers to switch between operating in the driver mode and the sensor mode comprises:

configuring the first haptic transducer to operate in the driver mode to generate the standing waves;

configuring the second haptic transducer to operate in the sensor mode; and

detecting, at the second haptic transducer, the variations in the generated standing waves caused by the user touch.

5. The method of claim 4 further comprising:

configuring the first haptic transducer to operate in the sensor mode;

configuring the second haptic transducer to operate in the driver mode to generate the standing waves; and

detecting, at the first haptic transducer, the variations in the generated standing waves caused by the user touch.

6. The method of claim 3 wherein determining the location of the user touch comprises:

receiving signals from each of the first and second haptic transducers indicating an amplitude of the variations in the standing waves caused by the user's touch;

computing a power spectrum value for the variations based on the amplitude; and

analyzing the computed power spectrum value to determine the location of the user touch on the display.

7. The method of claim 1 further comprising:

measuring a propagation time of a transient wave at one or more sensors disposed on the display; and

determining the location of the user's touch based on variations in the transient wave caused by the user touch.

8. The method of claim 2 wherein the first and second haptic transducers are disposed on perpendicular sides of the display.

9. The method of claim 8 wherein activating the first and second haptic transducers comprises configuring the first and second haptic transducers to vibrate the display at different frequencies.

10. The method of claim 1 wherein detecting a sound of the standing waves affected by the user touch comprises detecting the sound of the variations in the standing wave using first and second microphones.

11. An electronic device comprising:

a display;

first and second haptic transducers connected to the display; and

a controller configured to:

control the first and second haptic transducers to generate standing waves that propagate through the display responsive to detecting a user touch on the display;

detect a sound of the standing waves affected by the user touch;

convert an amplitude of the detected sound into digitized signals;

compute an acoustic signature for the amplitude based on the digitized signals; and

determine a location of the user touch on the display based on the computed acoustic signature.

12. The device of claim 11 further comprising first and second microphones connected to the display to detect the sound of the standing waves affected by the user touch.

13. The device of claim 11 wherein the controller is further configured to alternately operate the first and second haptic transducers in a driver mode to generate the standing waves, and a sensor mode to detect variations in the standing waves caused by the user touch.

14. The device of claim 13 wherein the controller is further configured to:

configure the first haptic transducer to operate in the driver mode to generate the standing waves in the display;

configure the second haptic transducer to operate in the sensor mode; and

detect, at the second haptic transducer, the variations in the standing waves caused by the user touch.

15. The device of claim 13 wherein the controller is further configured to:

configure the first haptic transducer to operate in the sensor mode;

configure the second haptic transducer to operate in the driver mode to generate the standing waves in the display; and

detect, at the first haptic transducer, the variations in the standing waves caused by the user touch.

16. The device of claim 15 wherein the controller is further configured to:

receive signals from each of the first and second haptic transducers indicating an amplitude of the variations in the standing waves caused by the user touch;

compute a power spectrum value for the variations in the standing waves based on the amplitude of the variations in the standing waves; and

analyze the computed power spectrum to determine the location of the user's touch on the display.

17. The device of claim 11 wherein the controller is further configured to:

measure a propagation time of a transient wave propagating through the display at one or more sensors disposed on the display; and

determine the location of the user's touch based on variations in the transient wave propagating through the display and on the measured propagation time.

18. The device of claim 11 wherein the first and second haptic transducers are disposed on perpendicular sides of the display, and are configured to generate the standing waves in a surface material of the display and further comprising:

first and second sensors disposed on the display opposite the first and second haptic transducers, respectively, the first and second sensors configured to detect variations in the standing waves caused by the user's touch.