Detecting touchdowns and liftoffs of touch objects
View Patent ↗A system comprises a processing device and a capacitive sense array that includes a plurality of electrodes is disclosed. When a touchdown of a touch object is detected, the change in a touch area (e.g., an area where the touch object is in contact with the touch panel) caused by the touchdown may not be reported as a movement of the touch object. When a liftoff of the touch object is detected, the change in the touch area caused by the liftoff may not be reported as a movement of the touch object.
1. An apparatus comprising:
a sense array; and
a processing device, coupled to the sense array, the processing device to:
detect a presence of a touch object proximate to the sense array;
when the presence of the touch object comprises a touchdown of the touch object or a liftoff of the touch object, refrain from reporting a new position of the touch object when a change in the position of the touch object is less than a first movement threshold; and
when the presence of the touch object is not the touchdown of the touch object or the liftoff of the touch object, report the position of the touch object when the change in the position of the touch object is greater than a second movement threshold.
2. The apparatus of claim 1 , wherein the processing device is further to:
report the position of the touch object when the change in the position of the touch object is greater than the first movement threshold and when the presence of the touch object comprises the touchdown of the touch object or the liftoff of the touch object.
3. The apparatus of claim 1 , wherein the processing device is further to:
refrain from reporting the new position of the touch object when the change in the position of the touch object is less than the second movement threshold and when the presence of the touch object is not the touchdown of the touch object or the liftoff of the touch object.
4. The apparatus of claim 1 , wherein the processing device is further to:
detect that an increase in capacitance values within a touch area is greater than a touchdown threshold; and
determine that the presence of the touch object comprises the touchdown of the touch object based on the increase in capacitance values.
5. The apparatus of claim 1 , wherein the processing device is further to:
detect that a decrease in capacitance values within a touch area is greater than a liftoff threshold; and
determine that the presence of the touch object comprises the liftoff of the touch object based on the decrease in capacitance values.
6. The apparatus of claim 4 , wherein the processing device is further to:
determine that the presence of the touch object comprises the touchdown of the touch object and the movement of the touch object; and
report the position of the touch object when the change in the position of the touch object is greater than the first movement threshold.
7. The apparatus of claim 5 , wherein the processing device is further to:
determine that the presence of the touch object comprises the liftoff of the touch object and the movement of the touch object; and
report the position of the touch object when the change in the position of the touch object is greater than the first movement threshold.
8. The apparatus of claim 1 , wherein the processing device is further to:
detect that an increase in a size of a touch area is greater than a touchdown threshold; and
determine that the presence of the touch object comprises the touchdown of the touch object based on the increase in the size of the touch area.
9. The apparatus of claim 1 , wherein the processing device is further to:
detect that a decrease in a size of a touch area is greater than a touchdown threshold; and
determine that the presence of the touch object comprises the liftoff of the touch object based on the decrease in the size of the touch area.
10. The apparatus of claim 1 , wherein refraining from reporting the new position of the touch object comprises:
refraining from reporting any position of the touch object;
storing new position of the touch object.
11. The apparatus of claim 1 , wherein refraining from reporting the new position of the touch object comprises:
reporting a previous position of the touch object.
12. A method comprising:
detecting a presence of a touch object proximate to a sense array;
when the presence of the touch object comprises a touchdown of the touch object or a liftoff of the touch object, refraining from reporting a new position of the touch object when a change in the position of the touch object is less than a first movement threshold; and
when the presence of the touch object is not the touchdown of the touch object or the liftoff of the touch object, reporting the position of the touch object when the change in the position of the touch object is greater than a second movement threshold.
13. The method of claim 12 , further comprising:
reporting the position of the touch object when the change in the position of the touch object is greater than the first movement threshold and when the presence of the touch object comprises the touchdown of the touch object or the liftoff of the touch object.
14. The method of claim 12 , further comprising:
refraining from reporting the new position of the touch object when the change in the position of the touch object is less than the second movement threshold and when the presence of the touch object is not the touchdown of the touch object or the liftoff of the touch object.
15. The method of claim 12 , further comprising:
detecting that an increase in capacitance values within a touch area is greater than a touchdown threshold; and
determining that the presence of the touch object comprises the touchdown of the touch object based on the increase in capacitance values.
16. The method of claim 12 , further comprising:
detecting that a decrease in capacitance values within a touch area is greater than a liftoff threshold; and
determining that the presence of the touch object comprises the liftoff of the touch object based on the decrease in capacitance values.
17. The method of claim 15 , further comprising:
determining that the presence of the touch object comprises the touchdown of the touch object and the movement of the touch object; and
reporting the position of the touch object when the change in the position of the touch object is greater than the first movement threshold.
18. The method of claim 16 , further comprising:
determining that the presence of the touch object comprises the liftoff of the touch object and the movement of the touch object; and
reporting the position of the touch object when the change in the position of the touch object is greater than the first movement threshold.
19. The method of claim 12 , further comprising:
detecting that an increase in a size of a touch area is greater than a touchdown threshold; and
determining that the presence of the touch object comprises the touchdown of the touch object based on the increase in the size of the touch area.
20. The method of claim 12 , further comprising:
detecting that a decrease in a size of a touch area is greater than a touchdown threshold; and
determining that the presence of the touch object comprises the liftoff of the touch object based on the decrease in the size of the touch area.