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

1. A method comprising:

using a capacitive sensor, determining capacitance associated with a conductive object through a capacitive sensing surface, during a period of time, to detect a presence of the conductive object;

determining a first velocity of the detected presence in a first direction relative to the capacitive sensing surface;

determining a second velocity of the detected presence in a second direction relative to the capacitive sensing surface;

detecting a change in the first velocity in the first direction at a first time;

detecting a change in the second velocity in the second direction at a second time; and

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

2. The method of claim 1 , wherein the first direction is towards the capacitive sensing surface and the second direction is away from the capacitive sensing surface.

3. The method of claim 1 , wherein the detecting of the change in the first velocity in the first direction includes detecting a peak in the first velocity in the first direction and the detecting of the change in the second velocity in the second direction includes detecting a peak in the second velocity in the second direction.

4. The method of claim 3 , wherein detecting the peak in the first velocity in the first direction and detecting the peak in the second velocity in the second direction comprises:

determining a first sharpness factor of the change in the first velocity in the first direction based on a height and width associated with the change in the first velocity in the first direction;

determining a second sharpness factor of the change in the second velocity in the second direction based on a height and width associated with the change in the second velocity in the second direction;

detecting the peak in the first velocity in the first direction based on comparing the first sharpness factor to a sharpness threshold; and

detecting the peak in the second velocity in the second direction based on comparing the second sharpness factor to the sharpness threshold.

5. The method of claim 1 , wherein the recognizing of the user command based on the difference between the first time and the second time includes recognizing the user command based on comparing the difference between the first time and the second time to a threshold.

6. The method of claim 1 , wherein determining the first velocity and the second velocity of the detected presence comprises determining rate of change of the capacitance, during the period of time, wherein the rate of change is representative of the first velocity and the second velocity of the detected presence.

7. The method of claim 6 , wherein detecting the change in the first velocity in the first direction at the first time comprises detecting a first peak of the rate of change of the capacitance at the first time, and detecting the change in the second velocity in the second direction comprises detecting a second peak of the rate of change of the capacitance at the second time.

8. The method of claim 7 , wherein the detecting of the first peak of the rate of change at the first time indicates a rising edge of the determined capacitance and the detecting of the second peak of the rate of change at the second time indicates a falling edge of the determined capacitance.

9. An apparatus comprising:

a plurality of capacitive sensor elements; and

a processing device coupled to the plurality of capacitive sensing elements, wherein the processing device is configured to:

determine capacitance associated with a conductive object through the plurality of capacitive sensor elements, during a period of time to detect presence of the conductive object relative to the plurality of capacitive sensing elements;

determine first velocity of the detected presence in a first direction relative to the plurality of capacitive sensor elements;

determine second velocity of the detected presence in a second direction relative to the capacitive sensor elements;

detect a change in the first velocity in the first direction at a first time;

detect a change in the second velocity in the second direction at a second time; and

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

10. The apparatus of claim 9 , wherein the first direction is towards the capacitive sensing surface and the second direction is away from the capacitive sensing surface.

11. The apparatus of claim 9 , wherein the change in the first velocity in the first direction includes a peak in the first velocity in the first direction and the change in the second velocity in the second direction includes a peak in the second velocity in the second direction.

12. The apparatus of claim 11 , wherein the processing device is configured to determine a first sharpness factor of the change in the first velocity in the first direction based on a height and width associated with the change in the first velocity in the first direction, determine a second sharpness factor of the change in the second velocity in the second direction based on a height and width associated with the change in second velocity in the second direction, detect the peak in the first velocity in the first direction based on comparing the first sharpness factor to a sharpness threshold, and detect the peak in the second velocity in the second direction based on comparing the second sharpness factor to the sharpness threshold.

13. The apparatus of claim 9 , wherein the processing device is configured to recognize the user command based on comparing the difference between the first time and the second time to a threshold.

14. The apparatus of claim 9 , wherein the processing device is configured to determine rate of change of the capacitance wherein the rate of change is representative of the first velocity and the second velocity of the detected presence.

15. The apparatus of claim 14 , wherein the processing device is configured to detect the change in the first velocity in the first direction at the first time as a first peak of the rate of change of the capacitance at the first time, and detect the change in the second velocity in the second direction as a second peak of the rate of change of the capacitance at the second time.

16. The apparatus of claim 15 , wherein the first peak of the rate of change at the first time indicates a rising edge of the determined capacitance and the second peak of the rate of change at the second time indicates a falling edge of the determined capacitance.

17. A system comprising:

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

a processing device coupled to the touch input surface, wherein the processing device is configured to detect presence of an input object relative to the touch input surface, determine first velocity of the detected presence in a first direction relative to the touch input surface, determine second velocity of the detected presence in a second direction relative to the touch input surface, detect a change in the first velocity in the first direction at a first time, detect a change in the second velocity in the second direction at a second time, and recognize a user command 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 command in an operation of the host system.

18. The system of claim 17 , wherein the processing device is configured to measure a capacitance associated with the input object through the one or more of the plurality of capacitive sensor elements and determine a rate of change of the capacitance signal, wherein the rate of change of the capacitance reflects the first velocity and the second velocity of the detected presence.

19. The system of claim 18 , 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 threshold, wherein the user command includes a touch gesture.

20. The apparatus of claim 17 , wherein the first direction is towards the capacitive sensing surface and the second direction is away from the capacitive sensing surface.