BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a capacitive proximity switch. Furthermore, the invention relates to an interior and/or exterior component for a motor vehicle which includes at least one capacitive proximity switch.

Producing vehicle components from fiber composite material, which can comprise carbon fibers, for example, which are embedded in a plastic matrix, is known in the prior art. The carbon fibers act as reinforcing fibers of the component, and the reinforcements can be laid out along the force flow lines. Components made of carbon-fiber-reinforced plastic are distinguished by having a low mass and high rigidity at the same time.

In addition to these properties, vehicle components made of fiber composite material conventionally do not have further functions.

Various solutions are known from the prior art for the contactless proximity detection of an object at a capacitive proximity sensor, which differ in the manner of the signal generation and the measurement.

A first principle known from the prior art for capacitive proximity detection provides the use of a capacitive proximity sensor having a single electrode. In this measurement principle, the capacitance of the electrode is detected in relation to the ground potential of the measurement electronics of the capacitive proximity sensor and analyzed. This measurement principle is also referred to as a “loading method”. If an object, such as a user, approaches the sensor electrode, the capacitance at the sensor electrode then changes, which can accordingly be detected and analyzed.

A further measurement principle known from the prior art provides a capacitive proximity sensor having two sensor electrodes. One sensor electrode is operated in this case as an emitting electrode and the other sensor electrode as a receiving electrode. The electrical alternating field emitted at the emitting electrode is coupled into the receiving electrode and measured via an electrical signal tapped at the receiving electrode. This method is also referred to as a “transmission method”, since it measures the transmission between an emitter and a receiver. If a user approaches the sensor electrodes, the electrical alternating field formed between the emitting electrode and the receiving electrode changes, which can be measured and analyzed accordingly.

Capacitive proximity switches are often produced as printed conductor tracks on films and then applied to components. The printed conductor tracks are normally visible. If they are not supposed to be visible, the film has to be applied behind the component, wherein the material of the component cannot influence the switch, however.

One object to be achieved of at least some embodiments is to provide a capacitive proximity switch in which the printing of conductor tracks can be omitted. A further object is to provide an interior and/or exterior component for a motor vehicle having such a capacitive proximity switch.

A capacitive proximity switch described here comprises, according to at least one embodiment, a fiber composite body which comprises an electrically nonconductive matrix and a plurality of fibers embedded in the matrix. The matrix can be, for example, a plastic matrix, which can comprise, for example, a thermoplastic or a thermosetting plastic or can consist thereof, respectively. Alternatively, the matrix can comprise a ceramic material or can consist thereof.

The terms “proximity switch” and “proximity sensor” here and hereafter are to include both contactlessly functioning sensors, in particular contactless capacitive sensors, and also contacting sensors, i.e., sensors which react to contact, for example, tactile capacitive sensors.

Furthermore, the capacitive proximity switch comprises at least one first capacitive proximity sensor, which comprises at least one sensor electrode, and at least one second capacitive proximity sensor, which comprises at least one further sensor electrode. The sensor electrode of the first capacitive proximity sensor and the further sensor electrode of the second capacitive proximity sensor each comprise at least one electrically conductive fiber, which are each embedded in the matrix. Furthermore, the sensor electrode and the further sensor electrode can each consist of an electrically conductive fiber.

The sensor electrode and the further sensor electrode are preferably each electrically conductively connected to a sensor analysis device. The sensor analysis device can be, for example, an analysis circuit. Alternatively, the sensor electrode can be connected to a first analysis circuit and the further sensor electrode can be connected to a second analysis circuit. The first capacitive proximity sensor and the second capacitive proximity sensor can each comprise, for example, a separate circuit. The individual capacitive proximity sensors are preferably configured in such a way that they can function independently of one another as proximity switches.

Because of the plurality of the capacitive proximity sensors, which can each comprise an electrically conductive fiber as a sensor electrode, a contactless touchpad can be implemented within the fiber composite body, by means of which, for example, a two-dimensional or three-dimensional user interface can be enabled as in the case of a sensor matrix. In particular, not only can a proximity of an object be detected, but rather an accurate position detection can be performed, so that, for example, a volume control or a light intensity control can be performed by means of the capacitive proximity switch.

According to a further embodiment, the sensor electrode and/or the further sensor electrode comprise one or more of the carbon fibers or consist of one or more carbon fibers.

According to a further embodiment, the sensor electrode and/or the further sensor electrode comprise one or more metallic fibers or consist of one or more metallic fibers.

According to a further embodiment, the capacitive proximity switch comprises a plurality of nonconductive fibers, which are arranged and/or embedded in the fiber composite body. The nonconductive fibers can be, for example, glass fibers. A separation of the electrically conductive fibers in the textile production process can be facilitated, for example, by means of the nonconductive fibers.

According to a further embodiment, the first capacitive proximity sensor and the second capacitive proximity sensor function on the principle of the loading method. The capacitive proximity sensors then do not comprise additional sensor electrodes, for example, in addition to the sensor electrode and/or further sensor electrode. Alternatively, the first capacitive proximity sensor the second capacitive proximity sensor can also function on the principle of the transmission method and can comprise additional sensor electrodes, which can also be implemented, for example, as electrically conductive fibers embedded in the matrix. For example, the capacitive proximity sensors can each comprise one or more reference electrodes, coupling electrodes, or shielding electrodes, which can be formed, for example, as fibers embedded in the matrix.

According to a further embodiment, the electrically conductive fibers of the sensor electrode and electrically conductive fibers of the further sensor electrode extend substantially in the same main propagation direction. For example, the electrically conductive fibers can extend substantially in parallel within the matrix.

According to a further embodiment, the electrically conductive fibers of the sensor electrode and electrically conductive fibers of the further sensor electrode extend in different main propagation directions. The electrically conductive fibers can extend, for example, substantially perpendicularly to one another.

According to a further embodiment, the electrically conductive fibers of the sensor electrode and electrically conductive fibers of the further sensor electrode have an essentially equal distance to a surface of the fiber composite body. For example, the electrically conductive fibers can have the same distance to a visible surface of the fiber composite body and/or to a visible surface of a component containing the fiber composite body.

According to a further embodiment, electrically conductive fibers of the sensor electrode and electrically conductive fibers of the further sensor electrode extend in different planes within the fiber composite body. The electrically conductive fibers can have, for example, different distances to a visible surface of the fiber composite body.

According to a further embodiment, the electrically conductive fibers of the sensor electrode and/or the electrically conductive fibers of the further sensor electrode are formed as unidirectional fibers and/or as endless fibers. Furthermore, the electrically conductive fibers of the sensor electrode and/or the electrically conductive fibers of the further sensor electrode can each be part of a fiber bundle.

According to a further embodiment, the fiber composite body furthermore comprises a plurality of electrically nonconductive fibers. The electrically nonconductive fibers can be, for example, glass fibers.

According to a further embodiment, the fibers of the fiber composite body are embodied as a fiber scrim, fiber woven fabric, fiber mesh, and/or as a fiber embroidery. The electrically conductive fibers of the sensor electrode and/or the electrically conductive fibers of the further sensor electrode can each be part of the fiber scrim and/or fiber woven fabric and/or fiber mesh or the fiber embroidery.

According to a further embodiment, the capacitive proximity switch comprises one or more further capacitive proximity sensors, which each comprise at least one sensor electrode, which respectively comprises at least one electrically conductive fiber which is embedded in the matrix.

Furthermore, an interior and/or exterior component for a motor vehicle is specified. The interior and/or exterior component comprises at least one capacitive proximity switch according to one of the above-mentioned embodiments.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

