FREQUENCY SHIFTING TECHNIQUES FOR CONCURRENT DISPLAY DRIVING AND TOUCH SENSING
Techniques for adjusting a sensing frequency of a sensing signal are provided. The techniques include performing sensing and display updates with frequencies that have an integer ratio. The techniques include detecting a noise signal with a frequency similar to the sensing frequency. The techniques also include varying the integer ratio to achieve a desired sensing signal frequency.
1 . A method for driving display updates and performing sensing, the method comprising:
driving a first plurality of display source lines for a first plurality of display line updates, wherein a first amount of time between a beginning of two consecutive display line updates of the first plurality of display line updates comprises a first display line time;
driving a plurality of capacitive sensor electrodes to perform a first number of sensing cycles during each of the first plurality of display line updates;
driving a second plurality of display source lines for a second plurality of display line updates, wherein a second amount of time between a beginning of two consecutive display line updates of the second plurality of display line updates comprises a second display line time; and
driving the plurality of capacitive sensor electrodes to perform a second number of sensing cycles during each of the second plurality of display line updates, wherein the second number of sensing cycles is different from the first number of sensing cycles.
2 . The method of claim 1 , wherein the first display line time is the same as the second display line time.
3 . The method of claim 1 , wherein the first display line time is different from the second display line time.
4 . The method of claim 3 , wherein a first ratio of the first display line time to the second display line time is different than a second ratio of the first number of sensing cycles to the second number of sensing cycles.
5 . The method of claim 1 , wherein driving the plurality of capacitive sensor electrodes with the second number of sensing cycles is performed responsive to detecting interference at a sensing frequency corresponding to the first number of sensing cycles.
6 . The method of claim 1 , wherein a beginning of a first sensing cycle of the first number of sensing cycles coincides with a beginning of the first display line time.
7 . The method of claim 1 , wherein an integration period of a first sensing cycle of the first number of sensing cycles is delayed from a beginning of the first sensing cycle.
8 . The method of claim 1 , wherein a number of sensing cycles that occurs in a display frame is an integer multiple of a number of display line times that occurs in the display frame.
9 . The method of claim 8 , wherein, during the display frame, each display line is updated.
10 . A processing system for driving display updates and performing sensing, the processing system comprising:
a display driver configured to:
drive a first plurality of display source lines for a first plurality of display line updates, wherein a first amount of time between a beginning of two consecutive display line updates of the first plurality of display line updates comprises a first display line time, and
drive a second plurality of display source lines for a second plurality of display line updates, wherein a second amount of time between a beginning of two consecutive display line updates of the second plurality of display line updates comprises a second display line time; and
sensor circuitry configured to:
drive a plurality of capacitive sensor electrodes to perform a first number of sensing cycles during each of the first plurality of display line updates, and
drive the plurality of capacitive sensor electrodes to perform a second number of sensing cycles during each of the second plurality of display line updates, wherein the second number of sensing cycles is different from the first number of sensing cycles.
11 . The processing system of claim 10 , wherein the first display line time is the same as the second display line time.
12 . The processing system of claim 10 , wherein the first display line time is different from the second display line time.
13 . The processing system of claim 12 , wherein a first ratio of the first display line time to the second display line time is different than a second ratio of the first number of sensing cycles to the second number of sensing cycles.
14 . The processing system of claim 10 , wherein driving the plurality of capacitive sensor electrodes with the second number of sensing cycles is performed responsive to detecting interference at a sensing frequency corresponding to the first number of sensing cycles.
15 . The processing system of claim 10 , wherein a beginning of a first sensing cycle of the first number of sensing cycles coincides with a beginning of the first display line time.
16 . The processing system of claim 10 , wherein an integration period of a first sensing cycle of the first number of sensing cycles is delayed from a beginning of the first sensing cycle.
17 . The processing system of claim 10 , wherein a number of sensing cycles that occurs in a display frame is an integer multiple of a number of display line times that occurs in the display frame.
18 . The method of claim 17 , wherein, during the display frame, each display line is updated.
19 . An input device for performing display updates and performing sensing, the input device comprising:
display source lines coupled to display elements, the display source lines including a first plurality of display source lines and a second plurality of display source lines;
a plurality of capacitive sensor electrodes; and
a processing system, comprising:
a display driver configured to:
drive the first plurality of display source lines for a first plurality of display line updates, wherein a first amount of time between a beginning of two consecutive display line updates of the first plurality of display line updates comprises a first display line time, and
drive the second plurality of display source lines for a second plurality of display line updates, wherein a second amount of time between a beginning of two consecutive display line updates of the second plurality of display line updates comprises a second display line time; and
sensor circuitry configured to:
drive the plurality of capacitive sensor electrodes to perform a first number of sensing cycles during each of the first plurality of display line updates, and
drive the plurality of capacitive sensor electrodes to perform a second number of sensing cycles during each of the second plurality of display line updates, wherein the second number of sensing cycles is different from the first number of sensing cycles.
20 . The input device of claim 19 , wherein a first ratio of the first display line time to the second display line time is different than a second ratio of the first number of sensing cycles to the second number of sensing cycles.