Active avoidance of display noise in simultaneous touch and display
Embodiments described herein include a method for avoiding display noise in a capacitive touch sensing device that includes sensing a touch input in a sensing region of an input device at a first touch sensing frequency. The method also includes analyzing incoming display data for display data noise at the first touch sensing frequency and at a second touch sensing frequency. If the display data noise at the first touch sensing frequency is higher than a threshold, touch sensing frequency is adjusted to the second touch sensing frequency where the display data noise is lower than the threshold. If the display data noise at the first touch sensing frequency is lower than the threshold, sensing is continued at the first touch frequency.
1. A method for avoiding display noise in a capacitive touch sensing device, comprising:
sensing a touch input in a sensing region of an input device at a first touch sensing frequency while, simultaneously updating, at least in part, a display of the input device;
analyzing incoming display data for display data noise at the first touch sensing frequency and at a second touch sensing frequency;
if the display data noise at the first touch sensing frequency is higher than a threshold, adjusting touch sensing frequency to the second touch sensing frequency where the display data noise is lower than the threshold; and
if the display data noise at the first touch sensing frequency is lower than the threshold, continuing sensing at the first touch sensing frequency, wherein the first touch sensing frequency and the second touch sensing frequency are parking frequencies of a display update frequency of the input device.
2. The method of claim 1 , where the incoming display data is analyzed for display data noise at the first touch sensing frequency and at the second touch sensing frequency using a Goertzel algorithm.
3. The method of claim 1 , where the incoming display data is analyzed for display data noise at a third touch sensing frequency, and:
if the display data noise at the first touch sensing frequency and the second touch sensing frequency are each higher than the threshold, adjusting the touch sensing frequency to the third touch sensing frequency where the display data noise is lower than the threshold.
4. The method of claim 1 , wherein analyzing incoming display data comprises analyzing display data stored in a buffer before the display data is transmitted to a display.
5. The method of claim 1 , further comprising:
while sensing at the first touch sensing frequency, detecting external noise that is higher than the threshold at the first touch sensing frequency; and
in response to detecting the external noise, adjusting the touch sensing frequency to the second touch sensing frequency where the display data noise is lower than the threshold.
6. The method of claim 1 , wherein the display data noise is generated by coupling impedance between sub-pixel routing and touch pixel routing.
7. An input device for capacitive touch sensing, comprising:
a capacitive touch sensor configured to:
sense a touch input in a sensing region at a first touch sensing frequency, while, the input device simultaneously updates, at least in part, a display; and
a processing system configured to:
analyze incoming display data for display data noise at the first touch sensing frequency and at a second touch sensing frequency;
if the display data noise at the first touch sensing frequency is higher than a threshold, adjust touch sensing frequency to the second touch sensing frequency where the display data noise is lower than the threshold; and
if the display data noise at the first touch sensing frequency is lower than the threshold, continue sensing at the first touch sensing frequency,
wherein the first touch sensing frequency and the second touch sensing frequency are parking frequencies of a display update frequency of the input device.
8. The input device of claim 7 , where the processing system is further configured to analyze incoming display data for display data noise at the first touch sensing frequency and at the second touch sensing frequency using a Goertzel algorithm.
9. The input device of claim 7 , where the processing system is further configured to:
analyze incoming display data for display data noise at a third touch sensing frequency; and
if the display data noise at the first touch sensing frequency and the second touch sensing frequency are each higher than the threshold, adjust the touch sensing frequency to the third touch sensing frequency where the display data noise is lower than the threshold.
10. The input device of claim 7 , further comprising a driver module that updates a display with incoming display data while the capacitive touch sensor simultaneously senses touch inputs.
11. The input device of claim 7 , wherein the processing system is further configured to analyze incoming display data stored in a buffer before the display data is transmitted to a display.
12. The input device of claim 7 , wherein the processing system is further configured to:
while sensing at the first touch sensing frequency, detect external noise that is higher than the threshold at the first touch sensing frequency; and
in response to detecting the external noise, adjust the touch sensing frequency to the second touch sensing frequency where the display data noise is lower than the threshold.
13. The input device of claim 7 , wherein display data noise is generated by coupling impedance between sub-pixel routing and touch pixel routing.
14. A processing system for avoiding display noise in a capacitive touch sensing device, the processing system comprising:
a receiver module configured to:
sense a touch input in a sensing region at a first touch sensing frequency while, simultaneously updating, at least in part, a display of the input device; and
processing circuitry configured to:
analyze incoming display data for display data noise at the first touch sensing frequency and at a second touch sensing frequency;
if the display data noise at the first touch sensing frequency is higher than a threshold, adjust touch sensing frequency to the second touch sensing frequency where the display data noise is lower than the threshold; and
if the display data noise at the first touch sensing frequency is lower than the threshold, continue sensing at the first touch sensing frequency,
wherein the first touch sensing frequency and the second touch sensing frequency are parking frequencies of a display update frequency of the input device.
15. The processing system of claim 14 , where the processing circuitry is further configured to analyze incoming display data for display data noise at the first touch sensing frequency and at the second touch sensing frequency using a Goertzel algorithm.
16. The processing system of claim 14 , where the processing circuitry is further configured to:
analyze incoming display data for display data noise at a third touch sensing frequency; and
if the display data noise at the first touch sensing frequency and the second touch sensing frequency are each higher than the threshold, adjust the touch sensing frequency to the third touch sensing frequency where the display data noise is lower than the threshold.
17. The processing system of claim 14 , further comprising a driver module that updates a display with incoming display data while the receiver module simultaneously senses touch inputs.
18. The processing system of claim 14 , wherein the processing circuitry is further configured to analyze incoming display data stored in a buffer before the display data is transmitted to a display.
19. The processing system of claim 14 , wherein the processing circuitry is further configured to:
while sensing at the first touch sensing frequency, detect external noise at the first touch sensing frequency; and
in response to detecting the external noise, adjust the touch sensing frequency to the second touch sensing frequency where the display data noise is lower than the threshold.