Capacitive control unit with self-capacitance sensor and at least partially electrically conductive control element

Abstract

Capacitive control unit (1) for a motor vehicle with a capacitive sensor element (31) designed as a self-capacitance sensor, which is designed to generate an electric field and to detect a change in the generated electric field, with a switching arrangement (10) which is designed to effect a change in the electric field when actuated by an operator (70), as well as with a cover element (20) having a visible side (21) and a back side (23), wherein the switching arrangement (10) is arranged on the visible side of the cover element (20) and the capacitive sensor element (31) is arranged on the rear or visible side of the cover element (20), wherein the switching arrangement (10) comprises an operating element (50) that is at least partially electrically conductive for actuation by the operator (70), a coupling electrode (11) coupled to the electric field, a sensor electrode (12) and at least two switching elements (40, 111 - 116) which can be actuated by a force applied to the operating element (50) by the operator (70), wherein the coupling electrode (11) is electrically connected to the switching elements (40, 111 - 116) and these to the sensor electrode (12), which is capacitively coupled to a counter electrode (32) for stabilizing a reference potential and which is electrically connected to the control element (50), such that when the operator (70) approaches the control element (50) and / or when the operator (70) touches the control element (50), a coupling with the reference potential can be established via the operator (70) and / or a respective change in the electric field detectable by the sensor element (31) can be effected, wherein each of the switching elements (40, 111 - 116) is assigned a predetermined capacitance (13, 14, 101 - 106), so that when the respective switching element (40, 111 - 116) is actuated by the coupling electrode (11) a change in the electric field which depends on the respective assigned capacitance (13, 14, 101 - 106) and which can be detected by the sensor element (31) can be effected.

Description

[0001] The invention relates to a capacitive control unit for a motor vehicle, and in particular for a seat of a motor vehicle, comprising a capacitive sensor element designed as a self-capacitance sensor. The capacitive control unit can be designed as a rocker switch, a slide switch, a rocker and slide button, or a combination of rocker and slide buttons or switches.

[0002] Various operating units, including those based on capacitive sensing, are known from the state of the art.

[0003] For example, DE 20 2022 103 370 U1 proposes a capacitive control unit in which a control element is separated from a sensor for detecting an operating input introduced via the control element, so that the sensor element can be provided as completely independent of the control element and not visible to the operator.

[0004] In this control unit, the operating element that can be moved by the operator must be made of an electrically conductive material or at least contain an electrically conductive contact. This results in a comparatively high manufacturing cost for the operating element and also imposes design limitations, as the operating element itself must not be directly touched by the operator in some areas.

[0005] To overcome this problem, DE 20 2024 101 391 U1 proposes to construct the operating element from an electrically non-conductive material and to provide the switching function via switching elements which, when actuated, connect a coupling electrode to a sensor electrode. Thus, each switching element is assigned a sensor electrode, and an electric field generated by a capacitive sensor element is altered in the area of ​​the respective sensor electrode. By sensing the position of the change in the electric field using the sensor element, it can be determined which switching element has been actuated and therefore which switching function should be triggered.

[0006] However, this approach also has some disadvantages. In particular, it should be emphasized that a separate sensor electrode is required for each switching element and thus for each switching function, resulting in a correspondingly large installation space requirement. It is also of particular importance that interference can erroneously cause a local change in the electric field, which can be incorrectly detected as the activation of a switching element.

[0007] Utility model DE 20 2024 105 266 U1 further discloses a capacitive control unit for motor vehicles which addresses the aforementioned problems. The solution known from the aforementioned utility model is to be further improved by the present invention, particularly with regard to reliability and interference immunity in the detection of changes in the electric field, as well as with a view to increased EMC robustness. The aim is to provide a capacitive control unit that ensures stable and error-free detection even under demanding environmental conditions and in the presence of electromagnetic interference.

[0008] The invention is therefore based on the objective of overcoming the aforementioned disadvantages and providing a capacitive control unit that is easy and inexpensive to manufacture, in which changes in the electric field can be detected in a disturbance-free manner, especially when the range of functions is simultaneously expanded, and which is insensitive to interference.

[0009] This problem is solved by the combination of features according to claim 1.

[0010] According to the invention, a capacitive control unit for a motor vehicle is proposed, comprising a capacitive sensor element, a switching arrangement, and a cover element having a visible side and a rear side, wherein the cover element preferably serves to separate the sensor element from the switching arrangement without contact. The switching arrangement is located on the visible side of the cover element, and the capacitive sensor element is preferably located on the rear side of the cover element, but alternatively also on the visible side of the cover element. In the case of a visible-side arrangement, a protective layer may additionally be provided between the sensor element and the switching arrangement to separate the sensor element from the switching arrangement without contact.In this context, "non-contact" means that the sensor element and the switching arrangement do not directly touch each other, but only indirectly via the cover element located between the switching arrangement and the sensor element. Optionally, further components, such as a decorative layer, a protective layer, or additional electronic components, may be arranged between the sensor element and the switching arrangement. The sensor element is a self-capacitance sensor and is thus designed to generate an electric field at one electrode of the sensor element and to detect a change in the generated electric field. The fundamental operating principle of the self-capacitance sensor is based on the detection of a change in capacitance between a single electrode and a reference potential, in particular ground (GND), whereby the change in capacitance is caused by the switching arrangement.In contrast, mutual capacitance sensors are based on measuring the change in capacitance between two crossed electrodes, and ITO films typically employ large-area electrodes similar to those used for mutual capacitance. Furthermore, the switching arrangement is designed to cause a change in the electric field when activated by an operator. It should be emphasized that the sensor element and the switching arrangement are connected to each other exclusively via the electric field or a change in the electric field, enabling data and information exchange. Therefore, activation of the switching arrangement is transmitted to the sensor element solely through a change in the electric field.For this purpose, the switching arrangement comprises a coupling electrode coupled to the electric field, preferably exactly one coupling electrode, at least two switching elements, and in particular exactly one sensor electrode. The sensor electrode is electrically connected to the switching elements, and the switching elements are connected to the coupling electrode, for example, via electrical conductors. The sensor electrode of the switching arrangement is not capacitively coupled to the sensor element or to the electrode of the sensor element, but rather capacitively coupled to a counter electrode to stabilize a reference potential. This counter electrode can be electrically connected to the reference potential, in particular ground (GND), and can also simultaneously correspond to the reference potential of the evaluation unit mentioned below.Furthermore, each switching element is assigned a predetermined capacitance, which can also be described as coding capacitances, wherein the capacitances preferably differ from each other, so that, in particular, exactly one coupling electrode can effect a change in the electric field when the respective switching element is actuated, which depends on the respective assigned capacitance and can be detected by the sensor element.

[0011] According to the invention, the switching arrangement further comprises an operating element that is at least partially electrically conductive for actuation by an operator. Accordingly, the at least two switching elements can be actuated by a force applied to the operating element by the operator, or in particular, mechanically actuated. For example, the operating element can be movably mounted and, when the operator applies force, transmit the force directly or via an intervening mechanism to the switching elements, thereby actuating them. Based on this, it is provided that the sensor electrode is electrically connected to the operating element, so that when the operator, and in particular their finger, approaches the operating element and / or touches the operating element, the sensor electrode is activated.whose finger can be coupled to the reference potential via the operator, thereby increasing the change in the electric field or the signal amplitude of the change when one of the switching elements is actuated, compared to a solution without coupling via the operator. Additionally or alternatively, it can be provided that approach and / or touch can cause a change in the electric field detectable by the sensor element, so that approach and / or touch can be detected by the sensor element and a distinction can be made between approach and touch.

[0012] To clarify, the electrical connection of the sensor electrode with the control element or its aforementioned conductive structure or its outer surface is not merely accidental or indeterminate, but, in addition to any necessary electrical conductors and contact pads, can be realized at least sectionally by a designated element, which is further described as a compensating element, so that the sensor electrode and the control element or its outer surface are always electrically connected as intended.

[0013] Such advanced training offers several advantages and positive effects. First, it should be noted that the electrical connection between the sensor electrode and the control element directly integrates the operator, or rather their finger, and thus the reference potential present at the operator, into the sensor circuit formed by the switching arrangement and its coupling electrode and sensor element. This means that the operator's approach to and / or contact with the control element directly influences changes in the electric field, and especially when the switching elements are actuated, resulting in a greater change in the electric field and a stronger signal amplitude detectable by the sensor element.

[0014] This leads to improved signal quality and enables more robust evaluation, as the signal-to-noise ratio is increased and interference, such as from electromagnetic fields or environmental influences, has less impact on the detection of the change by the sensor element.

[0015] Another advantageous aspect is the extended functionality. The capacitive control unit can not only detect the actual actuation via the switching elements, but optionally also the approach of the operator or their finger to the control element (proximity function) as well as, optionally, a touch of the control element by the operator or their finger (touch function).

[0016] This allows, in addition to the mechanical actuation of the switching elements, the detection of proximity and / or touch, which can be used to control additional functionalities as well as for safety checks.

[0017] Furthermore, the response time to user input can be significantly reduced by the early detection of proximity or touch, which increases user-friendliness.

[0018] Based on this, an advantageous embodiment of the invention provides that an outer surface, and in particular only an outer surface, of the control element is electrically conductive. Additionally or alternatively, the control element may have a conductive structure, which is preferably integral with a body that determines the shape of the control element. The conductive structure may, for example, form an outer surface, an inner surface, or an intermediate layer between these surfaces. Furthermore, the electrical structure may be formed, for example, by a continuous layer or a grid-like structure. Alternatively, the control element may be made of a solid, electrically conductive material.Regardless of the specific design of the control element, it is essential that it is designed to transmit the finger potential and enable coupling.

[0019] For example, the control element, or at least its outer surface, can be formed, at least partially, by a solid metallic body, a metallic foil, a metallic and / or conductive coating, or an electrically conductive plastic, such that these preferably enclose the control element on the outside. Alternatively, the control element can merely be defined by these variants, such that the control element may, for example, have a protective layer sealing the outer surface, which itself is not necessarily electrically conductive.

[0020] As already explained, it is advantageous if the electrical connection between the sensor electrode and the control element is permanent and reliable. Therefore, it is preferably provided that the electrical connection between the sensor electrode and the control element is formed, at least in sections, by an electrically conductive, flexible compensating element, which can compensate for relative movement between the sensor electrode, or, for example, a base plate on which the sensor electrode is mounted, and the control element. In a simple case, such a flexible compensating element can be a flexible conductor, a flexible circuit board, or an electrically conductive spring, each designed to compensate for relative movement between the sensor electrode and the control element and to establish a permanent electrical connection between them.In addition to other electrical conductors, such as conductor tracks on the PCB-based base plate, other elements, such as a contact pad, can also be provided for this purpose, against which the spring or, more generally, the flexible compensating element is supported.

[0021] Since the capacitance associated with a switching element and the resulting change in the electric field are predetermined and therefore known, the corresponding switching element can be directly assigned to the change in the electric field detected by the sensor element, so that it is possible to determine which switching element was actuated from the change, i.e., its course and magnitude or strength, or from the absolute values ​​of the electric field resulting from the change.

[0022] Compared to previously known control units, this not only saves installation space, since only a single coupling electrode is required for each switching element instead of multiple coupling electrodes, but also reduces susceptibility to interference, as the change in the electric field remains essentially unchanged even under interference. Assuming the installation space requirement remains the same compared to a solution with multiple coupling electrodes, the coupling electrode can be made larger or have a larger sensor area, thereby improving the signal strength and allowing for a thicker cover element.

[0023] The targeted referencing of the sensor element or each electrode of the sensor element against the reference potential enables stable and repeatable detection of actuations, even under difficult environmental conditions, thus increasing EMC robustness in particular.

[0024] Capacitors, and especially ceramic capacitors, can be used as capacitances or coding capacitances.

[0025] The miniaturization of the switching arrangement's footprint on the cover element, made possible by the invention, and the simultaneous increase in signal strength or detectable changes in the electric field, allows a switching arrangement, such as a seat adjustment switch, to be sensed through cover element thicknesses of, for example, 10 mm, which was previously impossible. This opens up novel design options, such as the possibility of a floating effect when the cover element is made of a transparent material. Furthermore, the sensor element can also be positioned below other components, such as LEDs or lighting modules, so that these are also located between the sensor element and the switching arrangement.

[0026] Regardless of whether the capacitive control unit is used as a seat adjustment switch or generally as a control unit for other functions, the switching arrangement can be designed as a rocker and / or slide button and alternatively or additionally as a rocker and / or slide switch. A button is preferably understood to be one that returns to a neutral center position, particularly spring-returned, from at least one of its actuated positions in which a switching element is mechanically actuated. Furthermore, a switch is preferably understood to be designed to remain in at least one of its actuated positions in which a switching element is mechanically actuated until manually reset and, in particular, to latch in a releasable manner.

[0027] If such a button or its operating element is spring-returned to a neutral center position, a spring provided for this purpose can integrally represent the flexible compensating element.

[0028] It is advantageous if the capacitive sensor element designed as a self-capacitance sensor and the counter electrode are positioned adjacent to each other on a common substrate, which can be, for example, a carrier film.

[0029] This enables a particularly compact and easy-to-install design. The immediate proximity of the sensor element and counter electrode ensures a defined reference potential for each sensor surface. This results in improved signal strength and increased robustness against electromagnetic interference and environmental influences.

[0030] Particularly when the sensor element has multiple electrodes, these and the counter electrode(s), if applicable, can be designed as segmented surfaces on the common substrate. This allows for the targeted placement of the sensor surfaces formed by the electrodes of the sensor element and the reference potential surfaces formed by the counter electrodes, thus reducing parasitic coupling and crosstalk between the channels formed by the electrodes. The segmented arrangement increases design flexibility and allows adaptation to various installation situations and geometries.

[0031] If the counter electrode and the sensor element are not on a common carrier but are designed independently of each other, the counter electrode can be arranged independently of the sensor electrode on the back or on the visible side of the cover element.

[0032] It can be provided that the sensor element has exactly one electrode coupled to each coupling electrode. Since it is an intrinsic capacitance sensor, the electrode is preferably designed both for generating the electric field and for detecting changes in the electric field, and the aforementioned evaluation unit can also be connected to the electrode for controlling the electrode and for evaluating changes in the electric field.

[0033] This establishes a clear assignment between the coupling electrode and the sensor electrode. This enables clearly defined signal routing and reduces crosstalk between adjacent channels. Signal acquisition becomes more robust and the distinguishability of individual actuations is improved.

[0034] Furthermore, the capacitive control unit can have several switching arrangements, which are, for example, arranged adjacent to each other on the cover element. The coupling electrodes of the switching arrangements are each coupled to a corresponding electrode of the sensor element.

[0035] The functionality of the control unit can be flexibly expanded by using multiple switching arrangements. Assigning each coupling electrode to its own electrode of the sensor element enables a modular design and reliable multi-channel acquisition.

[0036] It is advantageous if the sensor electrodes of the switching arrangements are each coupled to a respective counter electrode, or several sensor electrodes of the switching arrangements are coupled to exactly one counter electrode, or all sensor electrodes of the switching arrangements are coupled to exactly one counter electrode.

[0037] These coupling options allow the control unit to be optimally adapted to various installation situations and requirements. The targeted arrangement of the counter electrodes contributes to further stabilizing the reference potential and thus to increasing signal quality and robustness.

[0038] It may also be provided that the electrode of the sensor element and the associated coupling electrode overlap perfectly in a view from the viewing side and are therefore essentially identical with regard to their respective size or area, so that the electrode of the sensor element is not, or need not be, a large-area sensor or a large-area ITO film.

[0039] Such an overlap and correspondence of the surfaces maximizes the capacitive coupling between the electrodes while minimizing the area required for each individual electrode. This leads to optimized utilization of the available area, as smaller surfaces exhibit lower coupling but reduce parasitic influences on the coupling. Furthermore, this arrangement helps to minimize interference and increase the operational reliability of the control unit.

[0040] An advantageous embodiment of the invention provides that the switching arrangement has a base plate fixed on the visible side of the cover element and preferably on the visible side of the cover element, on which the coupling electrode and / or the sensor electrode are arranged.

[0041] Based on this, it can further be provided that the coupling electrode or the sensor electrode is designed as an electrically conductive frame surrounding the base plate on the cover element. Alternatively, the coupling electrode or the sensor electrode can be arranged on a frame surrounding the base plate on the cover element.

[0042] If a base plate is provided, the coupling electrode or the sensor electrode, or both, are designed, for example, as thin contact surfaces on the base plate, and in particular on a side of the base plate facing the sensor element. If both the coupling electrode and the sensor electrode are provided on the base plate, one of the electrodes, and in particular the coupling electrode, can surround the other in a frame-like manner. If only the coupling electrode or the sensor electrode is provided on the base plate, the other electrode can be arranged as the conductive frame or on the frame that surrounds the base plate.

[0043] An adhesive layer can be arranged between the base plate and the cover element to fix the base plate to the cover element. However, other types of adhesive layers are also possible for fixing the base plate to the cover element. For example, the base plate could be snapped or screwed to the cover element. Additionally or alternatively, a frame-shaped shield can be arranged between the base plate and the cover element. This shield is designed to protect the electric field between the capacitive sensor element and the coupling electrode from interference or to isolate the capacitive coupling between the sensor electrode and the counter electrode.

[0044] If an adhesive layer and preferably a liquid adhesive used during processing until it hardens are provided as the bonding layer for the production of the adhesive or bonding layer, the frame-shaped shield can also serve as an integral boundary for the adhesive, which is initially liquid, and be designed accordingly.

[0045] Furthermore, the capacitive control unit can include an evaluation unit connected to the sensor element, enabling signal exchange. The evaluation unit is designed to determine, from the change in the electric field detected by the sensor element, the switching element whose actuation led to the change in the electric field.

[0046] In this regard, it is important to first establish that the evaluation unit, for example, analyzes the temporal progression of the change, so that a switching of a sensor element is only detected if the change follows a predetermined, particularly steep, profile. The signal detected by the sensor element, for instance, exhibits a steep edge. If the change does not occur suddenly, i.e., if it does not have a steep edge, it may be caused by external disturbances.

[0047] If the evaluation unit detects an actuation of a switching element – ​​for example, through steep edges in the signal measured by the sensor element – ​​the magnitude or delta of the change can be evaluated and assigned to a capacitance or encoding capacitance, thus directly identifying the switching element to which the capacitance is assigned. Based on this, a function assigned to the switching element can be triggered.

[0048] Starting from such an evaluation unit, it can also be provided that the evaluation unit is further designed to determine, in the case of a change in the electric field caused by the operator approaching the control element or its outside, that the operator is approaching the control element (proximity function).

[0049] Additionally or alternatively, the evaluation unit can also be designed to determine, based on the change in the electric field caused by the operator touching the control element or its outer surface, that the operator is touching the outer surface or the control element (touch function).

[0050] In both cases, approach or contact does not necessarily lead to a change in the electric field via the coupling electrode, since a change in the electric field acting via the sensor electrode and / or, for example, a contact pad and / or, for example, via the control element itself can also be detected by the sensor element or its electrode.

[0051] Based on this, the evaluation unit can be designed to assign a function to the detected proximity and / or touch, and thus trigger a function. For example, actuators can be activated as soon as proximity is detected, which are then controlled by functions assigned to the switching elements, thereby improving the overall system's reaction time.

[0052] Alternatively or additionally, the evaluation unit can be configured to use the detected proximity and / or touch as a safety check for triggering a function assigned to the switching elements. For example, if a change in the electric field is detected and assigned to a switching element, the function assigned to the switching element is only triggered if a touch of the control element is detected at the same time.

[0053] It is often designed so that only one switching element can be actuated at a time, using appropriate guide elements and stops. In this case, it is sufficient if the coding capacitances differ, so that the switching element that can be actuated can be determined from the change in the electric field corresponding to the coding capacitance.

[0054] Depending on the application, and for example in seat adjustment switches, it may also be possible to operate several switching elements simultaneously. If the electric field changes due to the simultaneous operation of several switching elements, the changes caused by the individual coding capacitances are superimposed. In such a case, it is preferred that the capacitances have predetermined values ​​by which the actuated switching elements can be determined when several are actuated simultaneously. For this purpose, the capacitances are preferably selected according to a geometric sequence of numbers, so that the actuated switching elements can be determined when several are actuated simultaneously.If the four capacitances of four switching elements are chosen, for example corresponding to the number sequence 1, 2, 4 and 8, it is possible to read from a change in the electric field which combination of switching elements is actuated, since both the actuation of a single switching element and each combination of actuated switching elements leads to a specific capacitive change.

[0055] The switching elements each preferably have an electrically conductive contact body for establishing the electrical connection between the coupling electrode and the sensor electrode and / or a housing on which action can be applied to actuate the respective switching element.

[0056] According to one variant in which the operating unit or its switching arrangement is designed as a slide button or slide switch, the switching arrangement preferably has a central support extending orthogonally to the cover element, on which the switching elements are held operable along a switching path running parallel to the visible side of the cover element.

[0057] Preferably, the switching arrangement has at least one group of two switching elements, wherein the two switching elements of the group are arranged in pairs and can be actuated in opposite directions.

[0058] Furthermore, the switching arrangement can have an electrically non-conductive operating element that can be actuated by the operator and is designed to have a direct switching effect on at least one of the switching elements when actuated.

[0059] The operating element can be configured to actuate at least one of the switching elements during a translational movement that is preferably essentially parallel to a visible surface of the cover element.

[0060] Furthermore, the control element can be formed in one piece and / or be spring-returned to a neutral center position and / or have a gripping surface on an outer side facing away from the switching elements for interaction with the operator.

[0061] An alternative variant, in which the control unit or its switching arrangement is designed as a rocker switch or push button, provides that the switching elements are arranged on an intermediate support extending parallel to the cover element, which can also be the base plate itself. The switching elements can be actuated in a direction orthogonal to the cover element, so that the control unit can be tilted between the switching elements and thus be designed as a rocker, and depending on its tilt, at least one of the switching elements is actuated.

[0062] On its visible side, the cover element can directly form a visible surface, whereas alternatively, it can be provided that a decorative layer is provided between the cover element and the switching arrangement and, for example, on the visible side of the cover element, preferably covering the cover element substantially completely.

[0063] If the cover element is transparent, it may also be provided that, in order to create a depth effect, the cover element has a decorative layer on its reverse side, and in particular on its back, which preferably covers the cover element essentially completely.

[0064] The features disclosed above can be combined in any way, provided that this is technically possible and they do not contradict each other.

[0065] Other advantageous embodiments of the invention are characterized in the dependent claims or are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. The figures show: Fig. 1 a first variant of a control unit with a control element in a neutral center position; Fig. 2 the capacitive control element according to Fig. 1 in an activated position; Fig. 3 a second variant of a control unit; Fig. 4 a third variant of a control unit; Fig. 5 an alternative design of a switching arrangement; Fig. 6 an equivalent circuit diagram of a fourth variant of an operating unit; Fig. 7 a signal waveform for the fourth variant of the control unit; Fig. 8 a replacement circuit diagram of a fifth variant of an operating unit; Fig. 9 a signal curve for the fifth variant of the control unit.

[0066] The figures are schematic examples. Identical reference symbols in the figures indicate identical functional and / or structural features.

[0067] According to the in the Fig. In the variants shown in Figures 1 to 4, the capacitive control unit 1 essentially comprises a capacitive sensor element 31 designed as a self-capacitance sensor, a switching arrangement 10 and a cover element 20 separating these from one another, wherein the sensor element 31 has exactly one electrode which is arranged and fixed on a rear side 23 or a rear surface of the cover element 20 and the switching arrangement 10 on a visible side 21 or a visible surface of the cover element 20.

[0068] The cover element 20 completely separates the switching arrangement 10 and the sensor element 31 from each other and makes them independent, so that apart from the indirect mechanical connection via the cover element 20, there is only an operative connection via an electric field. For this purpose, the sensor element 31 is designed to generate an electric field at its electrode and to detect any change, or its course and magnitude, at this electrode.

[0069] The switching arrangement 10 is designed to cause a change in the electric field when actuated by an operator, which can be detected accordingly by the sensor element 31.

[0070] For this purpose, the switching arrangement 10 has a coupling electrode 11 coupled to the electric field and in this case exactly one coupling electrode 11, in this case two switching elements 40, whereby more switching elements 40 can also be provided, and regardless of the number of switching elements 40, in this case exactly one sensor electrode 12, wherein a capacitor 13, 14 is arranged in each electrical path leading over a switching element 40, so that each switching element 40 is assigned a predetermined capacitor 13, 14, through which a predetermined change in the electric field occurs when the switching element 40 is actuated.

[0071] To stabilize the reference potential, the sensor electrode 12 is capacitively coupled to a counter electrode 32, which is connected to a reference potential, for example ground (GND).

[0072] In the present case, the electrode of the sensor element 31 and the counter electrode 32 are realized adjacent to each other on a common carrier 30 designed as a carrier film.

[0073] Since the capacitances 13, 14 and thus the resulting change in the electric field are known in advance, it is possible to deduce which switching element 40 was actuated from the change in the electric field detected by the sensor element 31.

[0074] According to the invention, the sensor electrode 12 is electrically connected to an operating element 50 that is at least partially conductive. When the operator or their finger 70 approaches or touches the operating element 50, the approach or at least the touch changes the electric field in such a way that this change can be detected by the sensor element 31.

[0075] Specifically, the coupling electrode 11 is provided for in the present case to be connected to the switching elements 40 via first electrical lines 71, and these switching elements 40 are connected to the sensor electrode 12 via second electrical lines 72. The capacitors 13 and 14, which can also be referred to as coding capacitors, are connected upstream of the switching elements 40 via the first electrical lines 71, although they can also be connected downstream of the switching elements 40. Furthermore, the sensor electrode 12 is also connected via the second electrical line 72 to an electrically conductive flexible compensating element 54, which, according to the Fig. 1 to 4 are exemplary examples of flexible ladders, but also in the variants according to the Fig. 1 to 4 can be designed as a spring, as is the case in Fig. 5 is shown.

[0076] The electrical connection of the sensor electrode 12 via the flexible compensating element 54 to the control element 50 compensates for any relative movement between the control element 50 and the sensor electrode 12 or the base plate 16 on which the sensor electrode 12 is arranged, as can also be seen from the comparison of the Fig. 1 and Fig. 2 is clearly evident.

[0077] According to the Fig. 1 to 4 the operating unit 1 or its switching arrangement 10 is designed as a sliding button, so that the actuation takes place along a direction parallel to the surface of the cover element 20.

[0078] If the control element 50 is moved from the neutral center position according to Fig. 1 by a force K applied by the operator or by his finger 70 along the first actuation path X or in a first actuation direction into a first actuated position according to Fig. When the control element 50 is deflected, a first switching element 40 is actuated by the control element 50, and at the same time the reference potential of the operator 70 is included via the electrical connection of the control element 50 with the sensor electrode 12, causing a change in the electric field. This is stabilized by the reference potential coupled in via the sensor electrode 12, generating a capacitance that changes the electric field. The capacitance corresponds in magnitude to the capacitance 14 assigned to the actuated switching element 40, but due to the inclusion of the reference potential of the operator 70, it exhibits a larger signal amplitude than a change in the electric field without the inclusion of the reference potential of the operator 70. Therefore, the signal amplitude, and thus the change, can be detected reliably.The change caused by the capacitance is detected by the sensor element 31, whereby the evaluation unit 60 can determine which of the switching elements 40 has been actuated from the change in the electric field corresponding to the capacitance 14.

[0079] When a deflection occurs in the direction opposite to the actuation path X due to a correspondingly opposite force, the operating element 50 actuates a second, opposite switching element 40, so that, via the associated capacitance 13, a change in the electric field corresponding to the capacitance 13 also occurs, which in turn can be detected by the sensor element 31, so that the evaluation unit 60 can determine from the change in the electric field which switching element 40 has been actuated.

[0080] As already mentioned, the control element 50 must be electrically conductive at least in sections, whereby in the variant according to Fig. 1 and Fig. 2 it is provided that the entire control element 50 is formed from a solid metallic material, so that the outer surface 51 is also electrically conductive.

[0081] However, since it is sufficient if at least the outer surface 51 is electrically conductive, it can also be provided that an electrically conductive film or coating 55 is provided on the outer surface 51 of a carrier body of the control element 50 which is not necessarily electrically conductive itself, as in the variant according to Fig. 3. Such a film or coating 55 need not be provided on the entire outer surface 51, but can – as shown – be limited to the grip surfaces of the operating element 50 intended for operation.

[0082] Additionally and as in Fig. As shown in Figure 4, the conductive film or coating 55 does not necessarily have to form the outer surface 51, but can merely define it and be covered by a non-conductive protective layer 56, which is preferably selected in such a way that the coupling of the control element 50 with the operator 70 is not significantly affected.

[0083] Regarding the one in the Fig. The mechanical structure shown in Figures 1 to 4, which is independent of the functional principle proposed according to the invention, shows that the switching arrangement 10 has a base plate 16 which is fixed to the visible surface of the cover element 20 by a bonding or adhesive layer 24. The sensor electrode 12 and, optionally, the coupling electrode 11 are arranged on the base plate 16 or between the base plate 16 and the visible side 21 of the cover element 20.

[0084] A central support 18 extends orthogonally from the base plate 16 to the visible surface of the cover element 20, and the two switching elements 40 are held on this support on two opposite sides. Furthermore, the operating element 50, whose outer surface 51 serves directly as a gripping surface for the operator, is spring-loaded to a neutral central position by spring elements 19.

[0085] The switching elements 40 have a movable, electrically conductive contact body 41 for the switchable connection of the coupling electrode 11 with the sensor electrode 12. This contact body is encased in a preferably non-conductive housing 42, so that projections 52, optionally provided on an inner side of the operating element 50, can act on the housing 42 to establish the electrical connection. However, the use of electrically conductive housings 42, particularly when using snap discs, is not excluded.

[0086] Regarding the spring return of the control element 50 to the neutral center position, it can alternatively be provided that the two switching elements 40 are spring-returned to an open, i.e., unactuated or unactuated, home position, with the control element 50, for example, in its neutral center position, resting directly against the switching elements 40 via the projections 52. If one of the switching elements 40 is spring-returned from an actuated position to its unactuated home position, the control element 50 is spring-returned simultaneously.

[0087] As in Fig. As shown in Figure 3, and particularly advantageous when using a liquid adhesive for the bonding layer 24, a shield 25 is provided on the base plate 16 which surrounds the bonding layer 24 in a frame-like manner, which on the one hand shields the electric field from interference and on the other hand can serve as a mechanical boundary for the liquid adhesive until it has hardened.

[0088] Furthermore, in Fig. 3 An independent and exemplary variant is shown, in which the cover element 20 is transparent and has a decorative layer 22 on the back, so that an optically appealing depth effect can be achieved by means of the transparent cover element 20, which is made of glass, for example.

[0089] The variant according to Fig. In addition to the base plate 16, figure 4 provides a surrounding frame 17, which in this case is metallic and integrally designed as a sensor electrode 12, thereby also integrally providing a shield for the coupling electrode 11.

[0090] Although this also applies to the other variants, in Fig. Figure 4 shows that the coupling electrode 11 has a large surface area, which improves the signal strength of the electric field detectable by the sensor element 31, so that the distance of the sensor element 31 from the coupling electrode 11 can also be increased.

[0091] This allows an additional functional layer 61 with further electrical components and in particular lighting elements, such as LEDs, to be arranged between the cover element 20 and the sensor element 31.

[0092] Furthermore, in Fig. 4 provided, but also possible in the other variants shown, that the spring elements 19 provided for the spring return of the operating element 50 serve integrally as the flexible compensating element 54.

[0093] In the Fig. Figure 5 shows an alternative embodiment of a switching arrangement 10, in which it is designed as a rocker switch. Instead of a slide switch, as used in the Fig. 1 to 4 is provided for, in the variants according to the Fig. 1 to 4 also a switching arrangement 10 designed as a rocker switch according to, for example, the Fig. 5 can be used.

[0094] Due to the design of the switching arrangement 10 as a rocker switch, the actuation does not occur along a direction parallel to the visible side, but along a direction orthogonal to the surface of the cover element 20. Thus, if an operator applies a force K to the rocker switch or to the outer surface 51 of the operating element 50, it pivots about the pivot axis R with one of its respective projections 52 against a respective switching element 40 and actuates it.

[0095] Instead of a central support 18, the switching arrangement 10 looks like this Fig. Figure 5 provides an orthogonally extending intermediate support, which is integrally formed with the base plate 16. Accordingly, the switching elements 40 as well as the capacitors or coding capacitors 13, 14 are arranged on the base plate 16 and electrically contacted with each other.

[0096] Furthermore, a pivoting or rocking mechanism 53 is provided on the base plate 16, by which the operating element 50 is held pivotable or rockable about the axis of rotation R. A spring return may be provided and, for example, may also be integrally formed by the switching elements 40, but is not shown here.

[0097] Furthermore, the flexible compensating element 54 is particularly advantageously designed as a single spring for use as a rocker switch, which, due to its central arrangement, only needs to deform minimally. For this purpose, the spring can also be housed in a guide body (not shown). To establish the electrical connection, the spring 54 is also supported on a contact pad 57.

[0098] Deviating from a schematic mechanical setup according to the Fig. 1 to 5 show the Fig. Figures 6 to 9 show an equivalent circuit diagram and associated signal waveforms of two different configurations of capacitive control units according to the invention. 1. Although the components shown in the Fig. 6 and Fig. The 8 equivalent circuit diagrams shown each represent an equivalent circuit diagram of a variant according to the Fig. The number 1 to 5 can be traded, as shown by the Fig. 6 and Fig. 8 preferably an equivalent circuit diagram of a capacitive control unit 1 designed as a seat adjustment switch. For clarification, it should be emphasized that the seat adjustment switch can also be a rocker and / or slide button / switch and that the equivalent circuit diagrams can also correspond to another capacitive control unit 1 which is not used as a seat adjustment switch.

[0099] The seat adjustment switch has six switching elements 111 to 116, which can be actuated alternately in pairs or completely independently of each other. Each switching element 111 to 116 is also assigned a predetermined capacitance or coding capacitance 101 to 106. The strands, each consisting of a switching element 111 to 116 and a coding capacitance 101 to 106, connect the coupling electrode 11 to the sensor electrode 12.

[0100] Both in the variant according to Fig. 6 as well as according to Fig. 8. It is true that the coding capacities 101 to 106 differ from each other.

[0101] Furthermore, according to the invention, the sensor electrode 12 is electrically connected to the outer surface 54 via the flexible compensating element 54, so that the reference potential, here ground (GND), of the operator 70 is directly involved and acts upon mechanical actuation of one of the switching elements 111-116. Additionally, when the operator approaches or touches the outer surface 51, the capacitance changes so significantly that this change is detectable by the sensor element 31, thus enabling the approach or touch to be detected.

[0102] Starting from a predetermined capacity in farads (F), according to the in Fig. In variant 6 shown, it is provided that capacities 101 to 106 differ by an identical delta each.

[0103] Constant interference can be taken into account directly due to the base signal or does not interfere with the detection of the change, since the changes determined by the coding capacities 101 to 106 are detected relative to the known base signal.

[0104] In Fig. Figure 7 shows time t plotted along the abscissa, where the unit is irrelevant for the representation, for example.

[0105] From t = 1, the switching element 111 is actuated, causing a change in the electric field E corresponding to the capacitance 101 belonging to the switching element 111. This predetermined change can be directly detected or measured by the sensor element 31 and subsequently by the Fig. 6 and Fig. 8 evaluation units not shown, 60 can be evaluated.

[0106] As can be seen from t = 7 onwards, fluctuations in the base signal can also occur due to disturbances, which can cause the base signal to change by, for example, 1×ΔF even without any actuation of the switching elements 111 to 116. However, by evaluating the course of the signal change, the evaluation unit 60 can recognize that the change does not follow a step-like curve predetermined by the closing of any of the switching elements 111 to 116, so that it is a change in the electric field caused by disturbances and no switching element 111 to 116 has been actuated.

[0107] Problematic in the Fig. 6 and Fig. The variant shown in Figure 7 requires that it be mechanically ensured that only one switching element 111 to 116 can be actuated at a time, since, for example, it is not possible to distinguish whether switching elements 111 and 112 or only switching element 113 have been actuated.

[0108] To overcome this problem, in the Fig. 8 and Fig. Figure 9 shows an otherwise identical variant in which the coding capacities 101 to 106 correspond to a geometric sequence of numbers and in this case according to the geometric sequence a n =a1·q n-1 with a1 (starting value) = 1 and q (fixed quotient) = 2 chosen, such that, starting from a predetermined delta for the capacity, the values ​​1×ΔF, 2×ΔF, 4××F, 8×ΔF, 16×ΔF and 32×ΔF result for the coding capacities 101 to 106.

[0109] Will be according to Fig. 9, for example, if a change in the electric field corresponding to 3×ΔF is detected, this can only be the case if the switching elements 111 and 112 are actuated, so that the simultaneous actuation of several switching elements 111 to 116 can also be detected and recognized. Reference symbol list: 1 Capacitive control unit 10 Switching arrangement 11 Coupling electrode 12 Sensor electrode 13, 14, 101-106 Capacities / Coding Capacities 16 Base plate 17 frames 18 middle supports 19 spring elements 20 cover element 21 Viewing side 22 decorative layer 23 Back 24 Bonding layer / adhesive layer 25 Shielding 30 carriers 31 Capacitive sensor element 32 Counter electrode 40, 111-116 Switching elements 41 contact bodies 42 cases 50 Control element 51 Outer surface / Grip surface 52 protrusions 53 Swivel or rocking mechanism 54 flexible compensating element 55 conductive coating 56 Protective layer 57 contact pads 60 evaluation units 61 Functional layer 70 operators / operator's fingers 71, 72 electrical lines QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2022 103 370 U1

[0003] DE 20 2024 101 391 U1

[0005] DE 20 2024 105 266 U1

[0007]

Claims

[1] Capacitive control unit (1) for a motor vehicle with a capacitive sensor element (31) designed as a self-capacitance sensor, which is designed to generate an electric field and to detect a change in the generated electric field, with a switching arrangement (10) which is designed to effect a change in the electric field when actuated by an operator (70), as well as with a cover element (20) having a visible side (21) and a back side (23), wherein the switching arrangement (10) is arranged on the visible side of the cover element (20) and the capacitive sensor element (31) is arranged on the rear or visible side of the cover element (20), wherein the switching arrangement (10) comprises an operating element (50) that is at least partially electrically conductive for actuation by the operator (70), a coupling electrode (11) coupled to the electric field, a sensor electrode (12) and at least two switching elements (40, 111 - 116) which can be actuated by a force applied to the operating element (50) by the operator (70), wherein the coupling electrode (11) is electrically connected to the switching elements (40, 111 - 116) and these to the sensor electrode (12), which is capacitively coupled to a counter electrode (32) for stabilizing a reference potential and which is electrically connected to the control element (50), such that when the operator (70) approaches the control element (50) and / or when the operator (70) touches the control element (50), a coupling with the reference potential can be established via the operator (70) and / or a respective change in the electric field detectable by the sensor element (31) can be effected, wherein each of the switching elements (40, 111 - 116) is assigned a predetermined capacitance (13, 14, 101 - 106), so that when the respective switching element (40, 111 - 116) is actuated by the coupling electrode (11) a change in the electric field which depends on the respective assigned capacitance (13, 14, 101 - 106) and which can be detected by the sensor element (31) can be effected. [2] Capacitive control unit according to claim 1, wherein an outer surface (51) of the control element (50) is electrically conductive and / or wherein the control element (50) has a conductive structure and / or wherein the control element (50) is formed from an electrically conductive solid material. [3] Capacitive control unit according to claim 1 or 2, wherein the control element (50) or at least its outer surface (51) is formed or defined at least section by a solid metallic body, a metallic foil, a metallic and / or conductive coating (55) or an electrically conductive plastic. [4] Capacitive control unit according to one of the preceding claims, wherein the electrical connection between the sensor electrode (12) and the control element (50) is formed at least section by an electrically conductive, flexible compensating element (54). [5] Capacitive control unit according to one of the preceding claims, wherein the capacitive sensor element (31) designed as an intrinsic capacitance sensor and the counter electrode (32) are formed adjacent to each other on a common carrier (30). [6] Capacitive control unit according to one of the preceding claims, wherein the sensor element (31) has exactly one electrode coupled to the respective coupling electrode (11) for each coupling electrode (11). [7] Capacitive control unit according to one of the preceding claims, comprising several switching arrangements (10) whose coupling electrodes (11) are each coupled to a respective electrode of the sensor element (31). [8] Capacitive control unit according to the preceding claim, wherein the sensor electrodes (12) of the switching arrangements (10) are each coupled to a respective counter electrode (32) or several sensor electrodes (12) of the switching arrangements (10) are coupled to exactly one counter electrode (32) or all sensor electrodes (12) of the switching arrangements (10) are coupled to exactly one counter electrode (32). [9] Capacitive control unit according to one of the preceding claims, further comprising an evaluation unit (60) connected to the sensor element (31) enabling signal exchange, which is configured to determine from the change in the electric field detected by the sensor element (31) the switching element (40, 111 - 116) whose actuation has led to the change in the electric field. [10] Capacitive control unit according to the preceding claim, wherein the evaluation unit (60) is further configured to determine, in the event of a change in the electric field caused by the approach to the control element (50) by the operator (70), that the operator (70) is approaching the control element (50), and / or in the event of a change in the electric field caused by the touching of the control element (50) by the operator (70), that the operator (70) is touching the control element (50).

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