Capacitive position sensor

摘要

A capacitive position sensor has a two-layer electrode structure. Drive electrodes extending in a first direction on a first plane on one side of a substrate. Sense electrodes extend in a second direction on a second plane on the other side of the substrate so that the sense electrodes cross the drive electrodes at a plurality of intersections which collectively form a position sensing array. The sense electrodes are provided with branches extending in the first direction part of the way towards each adjacent sense electrode so that end portions of the branches of adjacent sense electrodes co-extend with each other in the first direction separated by a distance sufficiently small that capacitive coupling to the drive electrode adjacent to the co-extending portion is reduced. Providing sense electrode branches allow a sensor to be made which has a greater extent in the first direction for a given number of sense channels, since the co-extending portions provide an interpolating effect. The number of sense electrode branches per drive electrode can be increased which allows a sensor to be made which has ever greater extent in the first direction without having to increase the number of sense channels.

主权项

1. A capacitive position sensor comprising:
a plurality of drive electrodes extending along a first axis on a first plane; a plurality of sense electrodes extending along a second axis on a second plane offset from the first plane so that, in plan view, the sense electrodes cross the drive electrodes at a plurality of intersections which collectively form a position sensing array; wherein the sense electrodes have branches extending in opposite directions along the first axis without crossing any adjacent sense electrode; wherein end portions of the branches of adjacent sense electrodes extend beyond one another in a direction toward each one's respective adjacent sense electrode along the first axis to define a coextensive portion of the branches, and are separated along the second axis by a distance sufficiently small that capacitive coupling to the drive electrode adjacent to the coextensive portion is reduced.