Touch screen element
View Patent ↗A capacitive two-dimensional (2D) touch panel has three sets of interleaved electrodes. A first set of electrodes is spaced apart along the y-direction and these are galvanically connected to each other by a resistive strip connected at either end to a connection line. A second set of electrodes is also arrayed along the y-direction and these are galvanically connected to each other via a notionally non-resistive first connection. A third set of electrodes is also arrayed along the y-direction and these are galvanically connected to each other via a notionally non-resistive second connection. The second and third sets of electrodes are interleaved without galvanic cross-conduction to provide a gradient along the x-direction to resolve touch position in the x-direction. The first set of electrodes resolves touch position along the y-direction. Passive or active capacitive sensing techniques may be used to acquire the position information from the 2D touch panel.
1. A device comprising:
a plurality of first electrodes, each extending in a first direction;
a resistive voltage divider coupled to each of the plurality of electrodes to provide a stepwise progression in voltage reduction between a first one of the first electrodes and each succeeding electrode along a second direction to provide second direction touch position information, the second direction being substantially perpendicular to the first direction;
a plurality of co-extending pairs of second and third electrodes having complimentary varying area over their distance of co-extension, each pair being disposed between adjacent first electrodes, the second electrodes being electrically coupled to each other and the third electrodes being electrically coupled to each other to provide first direction touch position information;
a connector coupled to the first one of the first electrodes;
a connector coupled to a last one of the first electrodes; and
at least one additional connector coupled to a first electrode between the first and last of the first electrodes, wherein the connector coupled to the first one of the first electrodes, the connector coupled to the last one of the first electrodes, and the at least one additional connector coupled to the first electrode between the first and last of the first electrodes are each connected to sensing circuitry of the device as an individual sensing channel.
2. The device of claim 1 wherein the first electrodes are substantially parallel to each other.
3. The device of claim 1 , wherein the resistive voltage divider and the first electrodes are formed in a single layer of material.
4. The device of claim 1 and further comprising:
a drive circuit having an output connected to the first electrodes and operable to supply a common drive signal comprising voltage pulses to the first electrodes, wherein the resistive voltage divider provides a stepwise progression in voltage of the voltage pulses from electrode to electrode; and
first and second sensing circuits having respective inputs connected to the plurality of second and third electrodes, each sensing circuit comprising a sampling capacitor for accumulation of charge transferred from the electrodes and a measurement circuit arranged to detect charge accumulated on the sampling capacitor.
5. The device of claim 1 wherein the second electrodes are coupled to each other via a conductive trace on a first side and the third electrodes are coupled to each other via a conductive trace on a second side opposite the first side.
6. A device comprising:
a plurality of first substantially parallel electrodes, each extending along a first axis;
a resistive voltage divider coupled to each of the plurality of electrodes to provide a reduction in accumulated charge between a first one of the first electrodes and each succeeding electrode along a second axis substantially perpendicular to the first axis to provide second axis position information as a function of touch position along the second axis, the second axis being substantially perpendicular to the first axis;
a plurality of second electrodes, each being disposed between adjacent ones of the first electrodes, the second electrodes having first axis gradient field generating shaped electrodes and being coupled to each other by a conductive wiring trace;
a plurality of third electrodes, each being disposed between adjacent ones of the first electrodes, the third electrodes having first axis gradient field generating shaped electrodes and being coupled to each other by conductive wiring trace, wherein the second and third electrodes are arranged in co-extending pairs to provide ratiometric capacitive signals as a function of touch position along the first axis;
a connector coupled to the first one of the first electrodes;
a connector coupled to a last one of the first electrodes; and
at least one additional connector coupled to a first electrode between the first and last of the first electrodes, wherein the connector coupled to the first one of the first electrodes, the connector coupled to the last one of the first electrodes, and the at least one additional connector coupled to the first electrode between the first and last of the first electrodes are each connected to sensing circuitry of the device as an individual sensing channel.
7. The device of claim 6 and further comprising a connector coupled to the conductive wiring trace coupling the second electrodes and a connector coupled to the conductive wiring trace coupling the third electrodes, wherein the connectors are coupled to channels of a capacitive sensing device, the capacitive sensing device being configured to operate the electrodes in a phase-synchronous manner.
8. The device of claim 7 , further comprising charge-transfer sensing circuits configured to be switched substantially in unison.
9. The device of claim 6 , wherein succeeding first, second and third electrodes have repeat dimensions scaled to be equal to or smaller than a human finger touch.
10. The device of claim 6 , wherein the co-extending pairs of electrodes have complementary tapers over their distance of co-extension.
11. The device of claim 6 , wherein the co-extending pairs of electrodes have adjacent blocks of varying area over their distance of co-extension.
12. The device of claim 6 , wherein the resistive voltage divider and the first electrodes are formed in a single layer of material.
13. The device of claim 6 and further comprising:
a drive circuit having an output connected to the first electrodes and operable to supply a common drive signal comprising voltage pulses to the first electrodes, the resistive voltage divider providing a stepwise progression in voltage of the voltage pulses from electrode to electrode; and
first and second sensing circuits having respective inputs connected to the plurality of second and third electrodes, each sensing circuit comprising a sampling capacitor for accumulation of charge transferred from the electrodes and a measurement circuit arranged to detect charge accumulated on the sampling capacitor.
14. The device of claim 6 wherein each pair of co-extending electrodes is separated from another pair of co-extending electrodes by a single electrode from the first plurality of electrodes.
15. The device of claim 1 wherein the resistive voltage divider comprises a plurality of portions extending in the second direction that directly interconnect adjacent ones of the first electrodes at alternating ends of the first electrodes.
16. The device of claim 6 wherein the resistive voltage divider comprises a plurality of portions extending along the second axis that directly interconnect adjacent ones of the first electrodes at alternating ends of the first electrodes.