Capacitive sensor for detecting the movement of an object

摘要

A capacitive sensor for detecting the movement of an object, such as actuation of a key of an operating unit, includes first and second electrodes that are provided for connection or mechanical coupling to or arrangement on the object, the distance of which second electrode from the first electrode changes when the object moves. The electrodes form a first capacitor with a volume between the electrodes, the size of which changes when the object moves. An evaluation unit determines a change of capacitance between the two electrodes resulting from a change of their spacing and volume. A deformable, non-gaseous first dielectric is arranged between the electrodes and defines at least one gas volume that is filled by a gaseous second dielectric that can escape from the gas volume when the two electrodes approach one another.

主权项

1. A capacitive sensor for detecting the movement of an object, the capacitive sensor comprising:
a first electrode, a second electrode provided for connection or mechanical coupling to, or for arrangement on, the object, whereby the distance of the second electrode from the first electrode changes when the object moves, the two electrodes forming a first capacitor with a volume between the electrodes, the size of the volume changing when the distance between the first and second electrodes changes, and an evaluation unit connected to the two electrodes and operative to determine a change of capacitance between the two electrodes resulting from a change of their spacing and the volume, wherein the volume includes a first part occupied by a deformable, non-gaseous first dielectric arranged between the two electrodes, and a second part filled with a gaseous second dielectric, wherein the first dielectric is a shaped body made of a deformable material, the shaped body having two outer sides respectively facing toward the electrodes, the two outer sides defining a thickness of the first dielectric that decreases from a center of the first dielectric to an outer periphery of the first dielectric, and at least one of the outer sides defining with the respective electrode a first portion of the gas-filled second part of the volume, wherein the first portion decreases in size when the electrodes approach one another so that at least a part of the gaseous second dielectric is caused to escape from the first portion of the gas-filled second part of the volume, and, wherein when the two electrodes approach one another, the first dielectric occupies a greater percentage of the volume between the electrodes and the gaseous second dielectric-occupies smaller percentage of the volume between electrodes; and wherein the shaped body has the shape of a lens with at least one of the two outer sides being convex in shape for contacting the respective electrode at a progressively increasing contact area as the shaped body deforms when the spacing between the electrodes is decreased.