Hybrid capacitive touch system design and method
In one embodiment, a system includes first lines of conductive material and a touch sensor comprising second and third lines of conductive material inside and outside the touch sensor. The first lines of conductive material are outside the touch sensor and disposed between second lines of conductive material outside the touch sensor and the third lines of conductive material outside the touch sensor. The system further includes logic that is configured when executed to apply a ground signal to the first lines of conductive material and sense touch inputs at the touch sensor using mutual-capacitive touch sensing in response to determining to operate in a mutual-capacitive mode of operation, and apply a voltage signal to the first lines of conductive material and sense touch inputs at the touch sensor using self-capacitive touch sensing in response to determining to operate in a self-capacitive mode of operation.
1. A system, comprising:
a first set of lines of conductive material;
a touch sensor comprising a second set of lines of conductive material and a third set of lines of conductive material, wherein:
the second set and third set of lines of conductive material are disposed inside the touch sensor and outside the touch sensor; and
the first set of lines of conductive material is disposed outside the touch sensor and between the second set of lines of conductive material disposed outside the touch sensor and the third set of lines of conductive material disposed outside the touch sensor; and
one or more non-transitory computer-readable storage media coupled to the touch sensor and embodying logic that is configured when executed by a processor to perform operations comprising:
determining whether to operate the touch sensor in a mutual-capacitive mode of operation or a self-capacitive mode of operation;
in response to determining to operate in a mutual-capacitive mode of operation, applying a ground signal to the first set of lines of conductive material and sensing touch inputs at the touch sensor using mutual-capacitive touch sensing; and
in response to determining to operate in a self-capacitive mode of operation, applying a voltage signal to the first set of lines of conductive material and sensing touch inputs at the touch sensor using self-capacitive touch sensing.
2. The system of claim 1 , wherein sensing touch inputs at the touch sensor using mutual-capacitive touch sensing comprises:
applying a drive signal to the second set of lines of conductive material; and
sensing signals on the third set of lines of conductive material.
3. The system of claim 2 , wherein the drive signal applied to the second set of lines of conductive material comprises a waveform signal.
4. The system of claim 1 , wherein sensing touch inputs at the touch sensor using self-capacitive touch sensing comprises:
applying a drive signal to the second set of lines of conductive material; and
applying a ground signal to the third set of lines of conductive material.
5. The system of claim 4 , wherein the voltage signal applied to the first set of lines of conductive material is the same as the drive signal applied to the second set of lines of conductive material.
6. The system of claim 1 , wherein determining whether to operate the touch sensor in a mutual-capacitive mode of operation or a self-capacitive mode of operation is based on sensed touch inputs at the touch sensor.
7. The system of claim 1 , wherein the logic is further operable to, in response to determining to operate in a self-capacitive mode of operation, sense touch inputs based on detected changes in the voltage signal on the first set of lines of conductive material.
8. A method, comprising:
determining to operate a touch sensor in a mutual-capacitive mode of operation;
in response to determining to operate in a mutual-capacitive mode of operation, applying a ground signal to a first set of lines of conductive material and sensing touch inputs at the touch sensor using mutual-capacitive touch sensing;
determining to operate the touch sensor in a self-capacitive mode of operation; and
in response to determining to operate in a self-capacitive mode of operation, applying a voltage signal to the first set of lines of conductive material and sensing touch inputs at the touch sensor using self-capacitive touch sensing.
9. The method of claim 8 , wherein the touch sensor comprises a second set of lines of conductive material and a third set of lines of conductive material, and sensing touch inputs at the touch sensor using mutual-capacitive touch sensing comprises:
applying a drive signal to the second set of lines of conductive material; and
sensing signals on the third set of lines of conductive material.
10. The method of claim 9 , wherein the drive signal applied to the second set of lines of conductive material comprises a waveform signal.
11. The method of claim 8 , wherein the touch sensor comprises a second set of lines of conductive material and a third set of lines of conductive material, and sensing touch inputs at the touch sensor using self-capacitive touch sensing comprises:
applying a drive signal to the second set of lines of conductive material; and
applying a ground signal to the third set of lines of conductive material.
12. The method of claim 11 , wherein the voltage signal applied to the first set of lines of conductive material is the same as the drive signal applied to the second set of lines of conductive material.
13. The method of claim 8 , wherein determining to operate the touch sensor in a mutual-capacitive mode of operation is based on sensed touch inputs at the touch sensor.
14. The method of claim 8 , wherein determining to operate the touch sensor in a self-capacitive mode of operation is based on sensed touch inputs at the touch sensor.
15. A non-transitory computer-readable medium embodying instructions that are configured when executed by the processor to perform operations comprising:
determining to operate a touch sensor in a mutual-capacitive mode of operation;
in response to determining to operate in a mutual-capacitive mode of operation, applying a ground signal to a first set of lines of conductive material and sensing touch inputs at the touch sensor using mutual-capacitive touch sensing;
determining to operate the touch sensor in a self-capacitive mode of operation; and
in response to determining to operate in a self-capacitive mode of operation, applying a voltage signal to the first set of lines of conductive material and sensing touch inputs at the touch sensor using self-capacitive touch sensing.
16. The non-transitory computer-readable medium of claim 15 , wherein the touch sensor comprises a second set of lines of conductive material and a third set of lines of conductive material, and the instructions are configured to sense touch inputs at the touch sensor using mutual-capacitive touch sensing by:
applying a drive signal to the second set of lines of conductive material; and
sensing signals on the third set of lines of conductive material.
17. The non-transitory computer-readable medium of claim 16 , wherein the drive signal applied to the second set of lines of conductive material comprises a waveform signal.
18. The non-transitory computer-readable medium of claim 15 , wherein the touch sensor comprises a second set of lines of conductive material and a third set of lines of conductive material, and the instructions are configured to sense touch inputs at the touch sensor using self-capacitive touch sensing by:
applying a drive signal to the second set of lines of conductive material; and
applying a ground signal to the third set of lines of conductive material.
19. The non-transitory computer-readable medium of claim 18 , wherein the voltage signal applied to the first set of lines of conductive material is the same as the drive signal applied to the second set of lines of conductive material.
20. The non-transitory computer-readable medium of claim 15 , wherein the instructions configured to determine to operate the touch sensor in a mutual-capacitive mode of operation are configured to determine to operate the touch sensor in a mutual-capacitive mode based on sensed touch inputs at the touch sensor.
21. The non-transitory computer-readable medium of claim 15 , wherein the instructions configured to determine to operate the touch sensor in a self-capacitive mode of operation are configured to determine to operate the touch sensor in a self-capacitive mode based on sensed touch inputs at the touch sensor.