Capacitive sensor for detecting the movement of an object

Abstract

The capacitive sensor for detecting the movement of an object, particularly for detecting the actuation of a key of an operating unit, is furnished with a first electrode (30; 32) and a second electrode (34; 36) which is provided for connection or mechanical coupling to or arrangement on the object, the distance of which second electrode from the first electrode changes (30; 32) when the object moves. The two electrodes (30, 34; 32, 36) form a first capacitor (26; 28) with a volume (40) between the electrodes (30, 34; 32, 36), the size of which changes when the object moves. An evaluation unit (38), which is connected to the two electrodes (30, 34; 32, 36) and determines a change of capacitance between the two electrodes (30, 34; 32, 36) resulting from a change of their spacing and volume, is further provided. A deformable, non-gaseous first dielectric (42) is arranged between the two electrodes (30, 34; 32, 36). The first dielectric (42) defines at least one gas volume (44) or, together with at least one of the two electrodes (30, 34; 32, 36) defines a gas volume (44) that is filled by a gaseous second dielectric, wherein at least a part of the second dielectric escapes from the gas volume (44) and from the volume (40) between the two electrodes when the two electrodes (30, 34; 32, 36) approach one another, and, when the two electrodes (30, 34; 32, 36) approach one another, the portion of the volume (40) between the two electrodes (30, 34; 32, 36) occupied by the first dielectric (42) increases and the portion of the volume (40) between the two electrodes (30, 34; 32, 36) occupied by the second dielectric decreases. (Figure 1)

Description

technical field [0001] The invention relates to a capacitive sensor for detecting the movement of an object, which is especially intended for vehicle components, such as climate control devices, infotainment devices, navigation devices, radios or generally human The keys for manual operation of the operating unit of the computer interaction interface. Background technique [0002] In most cases the motion detection of the object in the form of a manually operated key which is detected to be operated will be accomplished by a mechanical switch comprising a switching device mechanically coupled to said key. Thus, when the key is operated, the switching device will be operated and in turn the switching device will establish a switch contact to signal the operation of the key. As an alternative to such mechanical methods, there are also capacitive systems in which the movement of an object is detected based on a change in capacitive capacity. Thus, regarding the example of a b...

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Problems solved by technology

However, in this respect, it is disadvantageous that air, or gas, generally only has a relatively low dielectric constant, so that the change in capacitance caused by a change in the distance between the two electrodes is only Will produce small signal changes

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