Method and apparatus for adapting operation of a device to touch-sensor malfunctions
An apparatus ( 12 ) and method ( 400 ) disclosed herein embody techniques for adapting read operations with respect to a touch sensor ( 14 ), to avoid or mitigate touch-detection problems arising from inoperative sensing lines ( 60 ) used to detect touch inputs to a touch surface ( 16 ) of the touch sensor ( 14 ). A particular advantage is that the avoidance or mitigation techniques address instances of touch sensor malfunctioning that involve isolated instances of sensing-line malfunctions. A further advantage is that the technique allows for continued “normal” organization, sizing, and placement of user-interface elements displayed on the touch surface ( 16 )—e.g., a touchscreen display surface—because the technique provides for touch detection in regions of the touch surface ( 16 ) affected by inoperative sensing lines ( 60 ), at least in cases where an inoperative sensing line ( 60 ) is bounded by operative sensing lines ( 60 ).
1. A method of operation by an apparatus interfaced with a touch sensor, the method comprising:
determining that a sensing line of the touch sensor is not operative and that respective sensing lines running adjacent to the inoperative sensing line are operative, the touch sensor having a plurality of sensing lines arranged for detecting touch inputs to a touch surface of the touch sensor;
adjusting a touch-detection sensitivity used for evaluating sensing signals output from the adjacent sensing lines, to provide touch detection within a region of the touch surface that corresponds to the inoperative sensing line and is bounded by the adjacent sensing lines;
adjusting one or both of an excitation frequency or an excitation voltage used to produce the sensing signals, in conjunction with adjusting the touch-detection sensitivity; and
evaluating the sensing signals for touch-detection according to the adjusted touch-detection sensitivity.
2. The method of claim 1 , wherein the method further comprises adjusting both the excitation frequency and the excitation voltage used to produce the sensing signals, in conjunction with adjusting the touch-detection sensitivity.
3. The method of claim 1 , wherein adjusting the touch-detection sensitivity comprises using a non-linear touch-detection threshold for evaluating an amplitude of the sensing signals, and wherein the non-linear touch-detection threshold is dependent upon the adjusted excitation voltage.
4. The method of claim 1 , further comprising adjusting a touch-detection sensitivity used for reading secondary adjacent sensing lines to account for the adjusted excitation voltage used with respect to the adjacent sensing lines, each secondary adjacent sensing line running adjacent to a respective one of the adjacent sensing lines.
5. The method of claim 1 , wherein adjusting the touch-detection sensitivity comprises using a non-linear touch-detection threshold for evaluating an amplitude of the sensing signals.
6. The method of claim 1 , further comprising at least one of:
skipping energization of the inoperative sensing line when reading the touch sensor for detection of touch inputs; or
skipping evaluation of a sensing signal output from the inoperative sensing line when reading the touch sensor for detection of touch inputs.
7. The method of claim 1 , further comprising ignoring any sensing signal output from the inoperative sensing line and calculating a location of a touch input detected in the region of the touch surface that corresponds to the inoperative sensing line as a function of the sensing signal output from one of the adjacent sensing lines in relation to the sensing signal output from the other one of the adjacent sensing lines.
8. The method of claim 1 , wherein the plurality of sensing lines comprises first and second pluralities of sensing lines with the sensing lines in one plurality running crisscross with the sensing lines in the other plurality, and wherein the method comprises:
detecting bounded sensing lines in either plurality, wherein any particular sensing line is a bounded sensing line if the particular sensing line is inoperative and the adjacent sensing lines are operative;
adjusting the touch-detection sensitivity used for evaluating sensing signals output from each pair of adjacent sensing lines; and
evaluating the sensing signals from each pair of adjacent sensing lines for touch-detection according to the adjusted touch-detection sensitivity.
9. The method of claim 1 , further comprising sending signaling to a host processor of an electronic device that includes the apparatus and the touch sensor, to thereby enable software-based mitigation with respect to the inoperative sensing line affecting use of the touch sensor as an input to one or more software applications executing on the host processor.
10. The method of claim 1 , wherein the plurality of sensing lines comprises capacitive lines configured for capacitance-based detection of touch inputs to the touch surface of the touch sensor.
11. An apparatus comprising:
read circuitry configured to interface with a touch sensor, the touch sensor having a plurality of sensing lines arranged for detecting touch inputs to a touch surface of the touch sensor; and
processing circuitry configured to:
control the read circuitry to excite respective sensing lines of the touch sensor and read corresponding sensing signals output from the touch sensor;
determine that a sensing line of the touch sensor is not operative and that respective sensing lines running adjacent to the inoperative sensing line are operative;
adjust a touch-detection sensitivity used for evaluating sensing signals output from the adjacent sensing lines, to provide touch detection within a region of the touch surface that corresponds to the inoperative sensing line and is bounded by the adjacent sensing lines;
adjust one or both of an excitation frequency or an excitation voltage used to produce the sensing signals, in conjunction with adjusting the touch-detection sensitivity; and
evaluate the sensing signals for touch-detection according to the adjusted touch-detection sensitivity.
12. The apparatus of claim 11 , wherein the plurality of sensing lines comprises first and second pluralities of sensing lines with the sensing lines in one plurality running crisscross with the sensing lines in the other plurality, and wherein the processing circuitry is configured to:
detect bounded sensing lines in either plurality, wherein any particular sensing line is a bounded sensing line if the particular sensing line is inoperative and the adjacent sensing lines are operative;
adjust the touch-detection sensitivity used for evaluating sensing signals output from each pair of adjacent sensing lines; and
evaluate the sensing signals from each pair of adjacent sensing lines for touch-detection according to the adjusted touch-detection sensitivity.
13. The apparatus of claim 11 , wherein the processing circuitry is configured to send signaling to a host processor of an electronic device that includes the apparatus and the touch sensor, to thereby enable software-based mitigation with respect to the inoperative sensing line affecting use of the touch sensor as an input to one or more software applications executing on the host processor.
14. The apparatus of claim 11 , wherein the plurality of sensing lines comprises capacitive lines configured for capacitance-based detection of touch inputs to the touch surface of the touch sensor.
15. The apparatus of claim 11 , wherein the processing circuitry is configured to perform at least one of:
skip energization of the inoperative sensing line when reading the touch sensor for detection of touch inputs; or
skip evaluation of a sensing signal output from the inoperative sensing line when reading the touch sensor for detection of touch inputs.
16. An electronic device comprising a touch sensor and the apparatus according to claim 11 .