Single layer touchscreen with ground insertion

1. A sensor array, comprising:

a plurality of first electrodes and a plurality of second electrodes, wherein each first electrode is coupled with at least one of the second electrodes via a mutual capacitance when the sensor array is in mutual capacitance mode; and

a plurality of third electrodes disposed between the first electrodes and the second electrodes, wherein at least one first electrode includes at least one opening formed therein and one third electrode of the plurality of third electrodes is at least partially disposed within each opening,

wherein the first electrodes, the second electrodes and the third electrodes are interleaved without intersecting one another and formed from a single layer of conductive material, and

wherein a surface area of the sensor array is divisible into a grid of N×M unit cells, wherein N and M are positive integers, wherein each of the N×M unit cells contains one first electrode, k second electrodes, and at least one third electrode, wherein the number of unit cells is greater than or equal to 2, and wherein k is greater than or equal to 2.

2. The sensor array of claim 1 , wherein each mutual capacitance between the first electrodes and the second electrodes includes a mutual capacitance measurement, wherein the third electrodes are configured to reduce an asymmetry of the mutual capacitance measurements between the first electrodes and the second electrodes.

3. The sensor array of claim 2 , wherein at least one third electrode is configured to be electrically coupled to a ground node when the sensor array is in mutual capacitance mode.

4. The sensor array of claim 1 , wherein at least one third electrode is configured to be electrically coupled to a sensor driver when the sensor array is in self capacitance mode.

5. The sensor array of claim 1 , wherein at least one third electrode is configured to be electrically coupled to a shield signal.

6. The sensor array of claim 1 , wherein at least one third electrode is coupled to a sensor controller configured to selectively and electrically couple the at least one third electrode to a transmit (TX) driver or a receive (RX) sense circuit.

7. The sensor array of claim 1 , wherein each of the first electrodes is wider than any of the second electrodes.

8. The sensor array of claim 1 , wherein each of the third electrodes disposed at least partially within the openings is substantially identical and rectangular.

9. The sensor array of claim 1 , wherein each of the third electrodes disposed at least partially within the openings is different at least in one of size, shape or orientation.

10. The sensor array of claim 1 , wherein each of the second electrodes is connected electrically to a different second electrode via a plurality of electrical traces, wherein at least one electrical trace is disposed between the first electrodes and the second electrodes and contributing to the asymmetry of the mutual capacitance measurements between the first electrodes and the second electrodes, wherein at least one third electrode is disposed between the at least one electrical trace and the first electrodes.

11. A capacitive sensor array, comprising:

a first set of sensor electrodes each comprising one or more large subelements;

a second set of sensor electrodes each comprising one or more small subelements, wherein each of the small subelements is smaller than any of the large subelements; and

a third set of sensor electrodes each comprising one or more insertion subelements, wherein the insertion subelements are disposed between the large subelements and the small subelements,

wherein the first set of sensor electrodes, the second set of sensor electrodes and the third set of sensor electrodes are interleaved without intersecting one another and formed from a single layer of conductive material, and

wherein a surface area of the capacitive sensor array is divisible into a grid of N×M unit cells, wherein N and M are positive integers, wherein each of the N×M unit cells contains one of the large subelements, k of the small subelements, and at least one of the insertion elements, wherein the number of unit cells is greater than or equal to 2, and wherein k is greater than or equal to 2.

12. The capacitive sensor array of claim 11 , wherein at least one of the unit cells includes a first region of greatest capacitive coupling between the large subelement and a first small subelement and a second region of greatest capacitive coupling between the large subelement and a second small subelement, wherein the first small subelement and the second small subelement are arranged along an axis parallel to a longitudinal axis of the large subelement and electrically isolated from each other, and wherein the at least one of the insertion subelements is disposed at least partially within the first region and the second region to reduce an asymmetry of capacitance measurements between the large subelement and the first and second small subelements.

13. The capacitive sensor array of claim 11 , wherein the insertion subelements are electrically coupled to a ground node in at least one operation mode.

14. The capacitive sensor array of claim 11 , wherein the insertion subelements are selectively and electrically coupled to a ground node, a TX driver, a RX sense circuit or a shield signal.

15. The capacitive sensor array of claim 11 , wherein at least one of the insertion subelements is electrically coupled to a sensor driver configured to drive the at least one of the insertion subelements in self capacitance mode.

16. The capacitive sensor array of claim 11 , wherein the surface area of the capacitive sensor array is divisible into M columns of the unit cells, wherein at least one of the insertion subelements is disposed between two of the M columns of the unit cells.

17. The capacitive sensor array of claim 11 , wherein the one large subelement in at least one unit cell defines a hollow shape, wherein the at least one of the insertion subelements is disposed at least partially within the hollow shape.

18. A system, comprising:

a capacitance sensor; and

a sensor array includes:

a plurality of first electrodes and a plurality of second electrodes, wherein each first electrode is capacitively coupled with at least one of the second electrodes, generating a mutual capacitance measurement, and

a plurality of third electrodes disposed between the first electrodes and the second electrodes, wherein the third electrodes are configured to reduce an asymmetry of the mutual capacitance measurements between the first electrodes and the second electrodes and wherein the first electrodes, the second electrodes and the third electrodes are interleaved without intersecting one another and formed from a single layer of conductive material,

wherein a surface area of the sensor array is divisible into a grid of N×M unit cells, wherein N and M are positive integers, wherein each of the N×M unit cells contains one first electrode, k second electrodes, and at least one third electrode, wherein the number of unit cells is greater than or equal to 2, and wherein k is greater than or equal to 2, and

wherein the capacitance sensor is configured to:

selectively operate the sensor array in mutual capacitance mode or self capacitance mode, and

selectively couple at least one third electrode to at least one of a ground node when the sensor array is in mutual capacitance mode, a sensor driver when the sensor array is in self capacitance mode, a shield signal, a RX sense circuit, or a TX signal driver.

19. The system of claim 18 , wherein at least one third electrode is inserted at least partially within the first electrodes.