Apparatus and method for recognizing a tap gesture on a touch sensing device

1. A method comprising:

determining a first velocity of a detected presence of a conductive object relative to movement of the conductive object in a direction towards a surface of the capacitive sensing device;

determining a second velocity of the detected presence relative to movement of the conductive object in a direction away from the surface of the capacitive sensing device;

detecting a first peak of the first velocity in the direction towards the surface at a first time;

detecting a second peak of the second velocity in the direction away from the surface at a second time; and

recognizing a gesture based on a difference between the first time and the second time.

2. The method of claim 1 , wherein the determining of the first and second velocity comprises:

determining a capacitance of the conductive object-through the capacitance sensing device; and

determining a rate of change of the capacitance, wherein the rate of change is representative of the first and second velocity of the detected presence, and wherein the recognizing of the gesture based on the relative difference between the first time and the second time comprises recognizing the gesture based on the rate of change of the capacitance.

3. The method of claim 2 , wherein determining the capacitance of the conductive object comprises:

determining a capacitance of each of a plurality of sensor elements of the capacitance sensing device; and

determining the capacitance of the conductive object as an average capacitance of the capacitance of each of the plurality of sensor elements, wherein recognizing the gesture is based on the average capacitance.

4. The method of claim 2 , wherein the recognizing of the gesture based on the rate of change of the capacitance comprises:

detecting a first peak of the rate of change at the first time;

detecting a second peak of the rate of change at the second time;

determining a difference between the first time and the second time; and

recognizing the gesture based on the difference between the first time and the second time being less than a time threshold, wherein the gesture includes a tap gesture.

5. The method of claim 4 , wherein the detecting of the first peak of the rate of change at the first time comprises detecting a rising edge of the capacitance in a positive direction, and wherein the detecting of the second peak of the rate of change at the second time comprises detecting a falling edge of the capacitance in a negative direction.

6. The method of claim 4 , wherein the recognizing of the tap gesture based on the rate of change of the capacitance comprises:

comparing a sharpness factor of the first peak of the rate of change to a sharpness threshold; and

comparing a sharpness factor of the second peak of the rate of change to the sharpness threshold, wherein the sharpness factor of the first peak of the rate of change is based on a height and a width of the first peak of the rate of change and the sharpness factor of the second peak of the rate of change is based on a height and a width of the second peak of the rate of change.

7. An apparatus comprising:

a sensing device having a plurality of capacitive sensor elements; and

a processing device coupled to the sensing device, wherein the processing device is configured to:

detect a presence of a conductive object relative to the sensing device through one or more of the plurality of capacitive sensor elements;

determine a first velocity of the detected presence relative to movement in a direction towards a surface of the sensing device;

determine a second velocity of the detected presence relative to movement in a direction away from the surface of the sensing device;

detect a first peak of the first velocity at a first time;

detect a second peak of the second velocity at a second time; and

recognize a gesture based on a difference between the first time and the second time.

8. The apparatus of claim 7 , wherein the processing device comprises a capacitance sensor coupled to the plurality of capacitive sensor elements, and wherein the capacitance sensor is configured to measure a capacitance of the conductive object through one or more of the plurality of capacitive sensor elements, wherein the processing device is configured to determine a rate of change of the capacitance and recognize the gesture based on the rate of change of the capacitance.

9. The apparatus of claim 8 , wherein the capacitance sensor comprises a relaxation oscillator coupled to the plurality of capacitive sensor elements, wherein the relaxation oscillator comprises:

a current source to provide a charge current to the plurality of capacitive sensor elements; and

a selection circuit coupled to the plurality of capacitive sensor elements and the current source, wherein the selection circuit is configured to sequentially select a capacitive sensor element of the plurality of capacitive sensor elements to provide the charge current and to measure the capacitance of each capacitive sensor element of the sensing device.

10. The apparatus of claim 9 , wherein the processing device is configured to determine the capacitance of the conductive object based on an average capacitance of the one or more of the plurality of capacitive sensor elements.

11. The apparatus of claim 8 , wherein the processing device is configured to:

detect a first peak of the rate of change at the first time;

detect a second peak of the rate of change at the second time;

determine a difference between the first time and the second time; and

recognize the gesture based on the difference between the first time and the second time being less that than a time threshold, wherein the gesture includes a tap gesture.

12. The apparatus of claim 11 , wherein the processing device is configured to detect a rising edge of the capacitance to detect the first peak of the rate of change at the first time and to detect a falling edge of the capacitance to detect the second peak of the rate of change at the second time.

13. The apparatus of claim 11 , wherein the processing device is configured to:

determine a sharpness factor of the first peak of the rate of change based on a height and width of the first peak of the rate of change; and

determine a sharpness factor of the second peak of the rate of change based on height and width of the second peak of the rate of change, wherein the processing device is configured to recognize the tap gesture based on a comparison between the sharpness factor of the first peak of the rate of change being and a sharpness threshold and a comparison between the sharpness factor of the second peak of the rate of change and the sharpness threshold.

14. The apparatus of claim 13 , wherein the processing device is configured to distinguish between the tap gesture and a non-tap gesture based on the sharpness factor of the first peak of the rate of change and the sharpness factor of the second peak of the rate of change.

15. The apparatus of claim 13 , wherein the sharpness factor of at least one of the first peak of the rate of change and the second peak of the rate of change is determined as the height of the at least one of the first peak of the rate of change and the second peak of the rate of change divided by the width of the at least one of the first peak of the rate of change and the second peak of the rate of change.

16. The apparatus of claim 11 , wherein a height of the at least one of the first peak of the rate of change and the second peak of the rate of change is a maximum of the rate of change.

17. The apparatus of claim 7 , wherein the conductive object is a finger.

18. The apparatus of claim 7 , wherein the sensing device comprises a single-dimension sensor array comprising the plurality of sensor element.

19. The apparatus of claim 7 , wherein the sensing device comprises a multi-dimension sensor array comprising the plurality of sensor elements.

20. The apparatus of claim 7 , wherein the sensing device is a touch-sensor pad.

21. The apparatus of claim 7 , wherein the sensing device is at least one of a touch-sensor pad or a touch sensor button.

22. The apparatus of claim 7 , wherein the sensing device is mounted on a mobile handset.

23. A system comprising:

a touch input surface including a plurality of capacitive sensor elements;

a processing device coupled to the touch input surface, the processing device configured to detect a presence of an input object relative to the touch input surface through one or more of the plurality of capacitive sensor elements; determine a first velocity of a detected presence in a direction towards the touch input surface and determine a second velocity of the detected presence in a direction away from the touch input surface; detect a first peak of the first velocity at a first time; detect a second peak of the second velocity at a second time; and recognize a gesture based on a difference between the first time and the second time; and

a host system coupled to the processing device, the host system configured use the recognized user gesture in an operation of the host system.

24. The system of claim 23 , wherein the processing device is configured to measure a signal of the input object through the one or more of the plurality of sensor elements and determine a rate of change of the signal, wherein the rate of change of the signal reflects the first and second velocity of the detected presence.

25. The system of claim 24 , wherein the processing device is configured to detect a first peak of the rate of change at the first time, detect a second peak of the rate of change at the second time, determine a difference between the first time and the second time, and recognize the user gesture based on a comparison between the determined difference and a time threshold, wherein the user gesture includes a tap gesture.