Guarding and shielding routing traces in proximity sensors

摘要

A capacitive input device has a sensor electrode pattern disposed on a first side of a substrate. The sensor electrode pattern comprises a plurality of sensor electrode elements disposed on the first side of a first substrate. A plurality of routing traces is disposed along a first edge of the sensor electrode pattern on the first side of the substrate and configured to communicatively couple at least some of the sensor electrodes with a processing system. A pair of guard traces is disposed in the same layer as and brackets the plurality of routing traces. A guard overlaps the routing traces, is disposed proximate the routing traces on the first side of the substrate, and ohmically couples the pair of guard traces with one another. A second insulator is disposed between the routing traces and the guard. The second insulator and the first insulator are disposed in the same layer.

主权项

1. A capacitive input device comprising:
a processing system; a sensor electrode pattern disposed on a first side of a substrate and comprising:
a plurality of sensor electrode elements disposed on said first side of said substrate;a first subset of said plurality of sensor electrode elements ohmically coupled into groups to form a first array of sensor electrodes oriented along a first axis; anda second subset of said plurality of sensor electrode elements ohmically coupled into groups by a plurality of jumpers to form a second array of sensor electrodes oriented along a second axis which is different from said first axis, wherein a first insulator is disposed between each of said plurality of jumpers and said first subset of said plurality of sensor electrode elements; a plurality of routing traces disposed along a first edge of said sensor electrode pattern on said first side of said substrate and configured to communicatively couple at least some of said sensor electrodes with said processing system; a pair of guard traces disposed outside of said sensor electrode pattern, along said first edge, in the same layer as said plurality of routing traces such that said pair of guard traces brackets said plurality of routing traces; a guard overlapping said routing traces and disposed proximate said routing traces on said first side of said substrate, and wherein said guard ohmically couples said pair of guard traces with one another by extending over said routing traces between a first coupling to a first of said pair of guard traces and a second coupling to a second of said pair of guard traces; and a second insulator disposed between said routing traces and said guard, wherein said second insulator and said first insulator are disposed in the same layer, wherein a thickness of said second insulator creates a maximum gap of T between said routing traces and said guard, and wherein said guard is spaced a distance of at least T/2 from a closest edge of an active sensor area of said sensor electrode pattern; wherein said processing system is configured to:
during transcapacitive sensing with said sensor electrode pattern, hold said guard at a constant potential; andduring absolute capacitive sensing with said sensor electrode pattern, modulate said guard with a guard signal that is based on a sensing signal driven through a routing trace.