DE202021003982U1 - switching element and component - Google Patents

Abstract

Switching element (1) with a plastic body (4), the switching element (1) forming a touch surface, the switching element (1) having a metal coating (3) with which a surface of the plastic body (4) is coated, and the metal coating (3) is at least partially produced by electroplating, characterized in that the surface faces away from the touch surface of the switching element (1).

Description

The invention relates to a switching element with a plastic body, the switching element forming a touch surface, the switching element having a metal coating with which a surface of the plastic body is coated, and the metal coating being produced at least partially by electroplating. The invention also relates to a component that is equipped with the switching element described above.

Electroplated switching elements are known from the prior art. The pamphlet DE 20 2019 103 960 U describes a control element made of plastic with symbols that can be backlit. This has an electroplated metal coating on the front. Such operating elements can be used in motor vehicles, for example. Due to the galvanically applied metal coating, they have a pleasant feel and are also abrasion-resistant and corrosion-resistant. The metal coating can consist of one or more layers of metal. Metals can be deposited on surfaces physically, chemically or electrochemically. A galvanic deposition process is a coating process in which material is deposited electrochemically.

Furthermore, the prior art knows capacitive switches. With capacitive switches, a variable capacitance of a sensor element is evaluated. This is how the pamphlet shows EP 2 388 920 A a capacitive switch with a metal coating and a cover plate. The metal coating and the cover plate together form a capacitor. The cover plate is spaced from the metal coating by a spacer. By exerting a force on the cover plate, it can be deformed, resulting in a change in a capacitance field between the metal plate and the cover plate. This change can be detected by a circuit so that the switch can output a control signal.

In connection with touch panels, galvanized components have hitherto been known, for example, as frame elements, for example in the publication TW 200951546 A described. A touch screen is specified here, which is surrounded by a galvanized frame. The pamphlet DE 25 45 371 B1 describes a galvanized switch. With this switch, a switching operation is generated by a user touching two electroplated electrode parts, as a result of which a switching current can flow between the two electrode parts.

The invention is based on the object of providing a switching element which can be activated when touched and/or approached and which is particularly robust. In addition, the object of the invention is to provide a component that has a switching element that can be activated when touched and/or approached and that is particularly robust. The objects are achieved by providing a switching element according to claim 1 and a component according to claim 16. The subclaims relate to various independent, advantageous developments of the present invention, the features of which can be freely combined with one another by a person skilled in the art within the scope of what is technically reasonable.

According to a first aspect of the invention, a switching element with a plastic body is proposed, with the switching element forming a touch surface, with the switching element having a metal coating with which a surface of the plastic body is coated, and with the metal coating being produced at least partially by electroplating. According to the invention, the surface faces away from the touch surface of the switching element. A change in a capacitance that changes when a finger approaches can be determined by means of the metal coating. The switching element can thus be actuated by touching the touch surface or by just approaching a finger to the touch surface, for example.

Since the metal coating is arranged opposite to the touch surface and does not form the touch surface, the metal coating is not directly touched when the switching element is actuated. This avoids problems that can occur when touching due to electrostatic discharge. Furthermore, the potentially sensitive metal coating is not directly exposed to touch, so that the switching element is more robust. If the metal coating is not exposed to physical contact, it does not have to be particularly durable. For example, a protective top layer can be dispensed with, which simplifies the manufacture of the metal coating. The fact that the metal coating is at least partially produced by electroplating means that the metal coating is at least partially produced by means of a galvanic, i.e. electrochemical deposition process, and that if the metal coating is formed by several metal layers lying on top of one another, at least one of the metal layers is formed by means of a galvanic ie electrochemical deposition process is generated. For example, it is possible for the metal coating to have a copper layer and a nickel layer. According to possible embodiments of the invention, the plastic body can be made very thin, so it can according to the invention be formed, for example, by a plastic film of small diameter to which the metal coating is applied.

It is advantageous if the plastic body is formed from a material comprising an acrylonitrile-butadiene-styrene copolymer and/or a polycarbonate. The plastic body particularly advantageously consists exclusively of an acrylonitrile-butadiene-styrene copolymer and/or of a polycarbonate. Acrylonitrile-butadiene-styrene copolymers are plastics made from terpolymers and/or mixtures of polymers and copolymers made from acrylonitrile, butadiene and styrene. Acrylonitrile butadiene styrene copolymers are very robust and are well suited for electroplating. Polycarbonates are thermoplastics and are also very robust. A mixture of an acrylonitrile-butadiene-styrene copolymer and a polycarbonate is preferably used. Such a blend can exhibit the strength and temperature resistance of polycarbonates and the flexibility of acrylonitrile-butadiene-styrene copolymers.

The plastic body is preferably formed by a transparent or a semi-transparent plastic material. Transparency means very good light transmission. If, on the other hand, the plastic body is semi-transparent or translucent, it does let light through, but is not transparent to the eye. For example, a transparent or semi-transparent plastic material can be backlit so that the touch surface lights up. Suitable starting materials for the plastic body are, for example, polycarbonates which are transparent or semi-transparent. However, other suitable plastic materials can also be used.

It can be provided according to the invention that the touch surface is formed by a colored plastic cover plate, by a transparent plastic cover plate or by a lacquer coating. A clear lacquer is preferably used. In this way, the plastic body can be protected from direct contact and at the same time an optically and/or haptically appealing touch surface can be created. According to other embodiments of the invention, the touch surface is formed directly by the plastic body.

According to a particular embodiment of the invention, the metal coating on the plastic body forms a sensor function section which is electrically insulated from other sections of the metal coating, the sensor function section having an electrode surface and the switching element having a lead which is electrically conductively connected to the electrode surface. It goes without saying that the feed line is also electrically conductive. The sensor function section is electrically isolated from all other sections of the metal coating. The sensor function section forms, so to speak, an electrically isolated island within the metal coating. The electrode surface can serve as an electrode of a capacitive sensor.

The supply line, which is electrically conductively connected to the electrode surface, makes it possible to also detect an electrical potential of the electrode surface from a remote location. This is achieved through the plastic body, so that touching the touch surface or just a finger approaching the touch surface can be detected. The feed line is preferably formed by the sensor function section. In this case, the electrically conductive supply line, like the electrode surface, is electroplated onto the plastic body.

The sensor function section is preferably electrically insulated from the other sections of the metal coating by an insulating section on the surface of the plastic body. According to the invention, it is possible for the metal coating to be interrupted by the insulating section, ie the metal coating is not present in the insulating section. For example, linear or flat insulation sections can be present on the plastic body. According to the invention, the other sections of the metal coating can form further sensor function sections and/or form non-functional sections.

The electrode surface preferably has a surface area of at least 0.2 cm ² . This enables the electrode surface to function as part of a capacitive sensor. However, depending on a layer thickness of the metal coating and a structure of the metal coating, in particular depending on the materials used for this purpose, the electrode surface can also have a smaller surface area. The electrode surface can be designed relatively freely with regard to its length and its width as well as the course of its outer contour. On the other hand, if the plastic body has a comparatively large diameter, then it may be necessary to correspondingly increase the surface area of the electrode surface.

According to the invention, the feed line can be a strip conductor that is narrow in size relative to the electrode surface. According to the invention, this can have a width of 0.5 mm to 3 mm. According to advantageous embodiments of the invention, the width of the supply line is 0.01% to 100% of a maximum diameter of the sensor function section. A very special advantage The width of the lead is 0.02% to 0.1% of the maximum diameter of the sensor function section. However, the supply line can also be dimensioned differently. According to possible embodiments of the invention, several supply lines can also be provided, so that an electrical potential of the electrode surface can be tapped off in different areas. In addition, according to advantageous embodiments, the sensor function section can have a plurality of electrode surfaces, so that the sensor function section can be actuated in different areas.

It can also be provided according to the invention that the switching element has a marking in or on the touch surface, which is aligned with the electrode surface. In this way, it can be pointed out on the outside where the electrode surface is located. The marking is preferably an optical marking formed by an imprint on the touch surface, by a transparent or semi-transparent section of the touch surface and/or by a recess in the touch surface. For example, the optical marking can be designed as a symbol, a letter or the like. If the touch surface is formed by the plastic body itself, then this can, for example, be subsequently printed or processed in some other way. For example, recesses can be subsequently introduced into a lacquer coating forming the touch surface. If a semi-transparent plastic cover plate is placed in front of the plastic body, which forms the touch surface, then the plastic cover plate is preferably made transparent only in sections in order to indicate the position of the electrode surface. According to other embodiments of the invention, the marking can be a haptic marking, such as a bump on the touch surface.

It is preferred if the metal coating has at least one viewing window. According to the invention, the viewing window can be formed by a recess in the metal coating. Light can pass through these when the switching element is backlit, for example when using the switching element as part of a component, wherein the component can be, for example, an illuminated switch or an illuminated body part of a vehicle that can be configured by touch. In this case, the plastic body should preferably be transparent or semi-transparent. It is particularly preferred if the metal coating has at least one viewing window that is arranged in the electrode surface. In this way, when the component is backlit, it can be seen on the touch surface side where the electrode surface is located. This is particularly advantageous if the switching element has a number of sensor function sections with which different functions can be triggered.

According to a further aspect of the invention, a component is proposed, comprising the switching element described above, further comprising a switching device, wherein the switching device is coupled to the supply line of the switching element, and wherein the switching device is set up to determine a capacitance and, depending on the determined capacity to output control signals. Such a device lends itself as a persistent control that can be used to trigger switching functions by touching it, even just by touching it with a finger. The component can, for example, form a switch, part of a control element or part of a switchable lighting element. Many other areas of application are conceivable.

The fact that the switching device is coupled to the supply line of the component can be understood in particular to mean that the switching device is electrically conductively connected to the supply line, for example via one or more cables. However, other coupling variants are also conceivable.

By means of the control signals, a lighting device can be activated or deactivated, for example. According to embodiments of the invention, the switching device can be a computer unit, for example a microcontroller. Alternatively, the switching device can be a combination of an electrical circuit and a computer unit. According to other embodiments of the invention, the switching device can be formed by a plurality of distributed computer units and/or electrical circuits, which together implement the above-described functioning of the switching device. According to the invention, other tasks such as control, regulation and/or monitoring functions can also be assigned to the switching device or components of the switching device.

According to advantageous embodiments of the invention, the switching device is set up to determine an intrinsic capacitance of the electrode surface. The intrinsic capacity of the electrode surface is calculated as a function of an electrical voltage applied to the electrode surface and a quantity of charge carriers which the electrode surface absorbs when this voltage is applied. The self-capacitance of the electrode surface changes when, for example, a finger is moved close to it. The intrinsic capacity of the electrode surface can, for example be determined in that the switching device alternately applies a high and a low electrical voltage to the electrode surface. This causes the electrode to be alternately charged and discharged. This is done with a certain clock frequency. According to the invention, an output pin and an input pin can be provided on the switching device. The switching device applies the alternating voltage to the electrode surface via the output pin. The switching device uses the input pin to measure how quickly the electrode surface charges or discharges. The intrinsic capacity of the electrode surface can be determined from a charging or discharging speed of the electrode surface.

According to alternative embodiments of the invention, however, instead of the intrinsic capacitance, a capacitance of a capacitor can be determined by the switching device, which the electrode surface forms together with a flat additional electrode of the component, the flat additional electrode being spaced apart from the electrode surface and being electrically insulated from the electrode surface. So a capacitor capacitance is measured. The capacitance of the capacitor changes when a finger is moved near the electrode area. The capacitance is measured in a similar way to measuring the intrinsic capacitance of the electrode surface. According to the invention, the flat additional electrode of the component can be formed by a separate metal element.

The capacity or the intrinsic capacity is preferably determined over a number of charging and discharging cycles. Here it is possible to determine an average value from the measured capacitance values of several charging and discharging cycles. In this way, an error correction of the capacitance measurement can take place. The cycle frequency of the charging and discharging is preferably adapted to a typical activation duration of the electrode surface.

The component preferably electrically insulates the touch surface from the metal coating. In this way, it is possible to avoid electrostatic discharges occurring when the touch surface is touched. This can be achieved structurally, for example. For this purpose, according to the invention, the component can have a housing in which the switching element is enclosed, so that the metal coating is electrically isolated from the sensing area. The housing is preferably formed from a non-electrically conductive material such as a plastic. In this way, a structural separation between the touch surface and the metal coating can be effected. Electrostatic discharges from the touch surface to the metal coating can thus be prevented.

The component preferably has an illuminant. The light source can be, for example, one or more LED light sources or halogen light sources. The light source is preferably arranged on a side of the switching element that faces away from the touch surface of the switching element. The switching element of the component can thus be backlit. According to the invention, for example, the component can form a cavity in which the lighting means is arranged and which the metal coating faces.

It is advantageous if the switching device is coupled to the lighting means, with the switching device being set up to control the lighting means as a function of the capacitance determined. Activation by control elements remote from the component is therefore not necessary. For example, an illumination intensity of an illumination component of an automobile body can be changed by touching it. However, it is also possible for the switching device to be coupled to other functional units such as lighting means, actuators or the like, which can be controlled by means of the component.

The component preferably has at least one other lamp in addition to the lamp, the lamp and the at least one other lamp being positioned in different areas of the component, and the switching element having at least one other sensor function section in addition to the sensor function section. Thus, a device is provided that has a plurality of illuminants and a plurality of sensor function sections, and whose illumination pattern can be easily configured by touching the sensor function sections. Each sensor function section can be assigned to one or more light sources. When a sensor function section is actuated, the lamp or lamps assigned to the sensor function section is/are actuated, so that these lamps can be switched on or off, change their color or be dimmed, for example. In the present case, dimming is to be understood as changing the brightness of a lighting means. According to embodiments of the invention, it can also be provided that several sensor function sections have to be actuated simultaneously and/or for specific periods of time in order to activate specific lighting configurations of the lighting arrangement. In order to implement the functionality described above, the switching device can be coupled to the plurality of sensor function sections.

The switching device is preferably set up to switch on the lighting means when a finger enters a region close to the electrode surface. A variable control of the lamp is possible. This is preferably implemented in such a way that the switching device is set up to switch on the light source temporarily when the finger is moved close to the electrode surface and to switch on the light source permanently when the finger touches the touch surface. According to the invention, the near area is an area of predefined size in the vicinity of the electrode surface.

The switching device is preferably set up to switch off the lighting means when the finger leaves the vicinity of the electrode surface. According to some embodiments of the invention, the light source is switched on continuously when the touch surface is touched by the finger, so that it remains switched on even when the finger is removed. Furthermore, it can be provided according to the invention that the illuminant is only switched off again by touching the touch surface again.

According to preferred embodiments of the invention, the vicinity of the electrode surface is understood to be a region adjoining the electrode surface which has a maximum diameter of less than 5 cm, preferably a maximum diameter of less than 4 cm and particularly preferably a maximum diameter of less than 3 cm. A form of the near area depends on a dimensioning of the electrode surface and generally extends mainly directly in front and behind, but only to a small extent laterally from the electrode surface.

Depending on whether a finger is moved in the vicinity of the electrode surface and in particular is brought so close to the electrode surface that it touches the touch surface, however, other methods for controlling the illuminant are also possible according to the invention. The switching device can be configured such that the light source is dimmed and/or a color of the light source is changed by moving the finger in the close range and the light source is switched on or off when the finger touches the electrode surface. Conversely, it is possible for the light source to be switched on or off by moving the finger in the close range and for the light source to be dimmed when the finger touches the touch surface.

It is advantageous if the switching device is set up to activate a functional unit when a finger is moved so close to the electrode surface that it touches the touch surface. When the touch surface is touched, a functional unit such as an actuator or any other functional unit can consequently be controlled. The fact that the functional unit is activated means that it is activated, deactivated, for example, or is influenced by the activation in any other way. The functional unit can, but does not have to be part of the component. Of course, the lighting means can also be activated beforehand when the finger approaches, as explained above.

• 1 eine schematische Darstellung eines erfindungsgemäßen Schaltelements mit einem Sensorfunktionsabschnitt in einer Draufsicht,
• 2 eine schematische Darstellung des Schaltelements gemäß 1 in einer Seitenansicht,
• 3 eine schematische Darstellung eines erfindungsgemäßen Bauteils,
• 4 ein Zeit-Spannungs-Diagramm zur Erläuterung einer Funktionsweise des erfindungsgemäßen Bauteils und
• 5 ein Zustandsdiagramm des erfindungsgemäßen Bauteils.

Advantageous exemplary embodiments are illustrated in the drawings. It shows:

• 1 a schematic representation of a switching element according to the invention with a sensor function section in a plan view,
• 2 a schematic representation of the switching element according to FIG 1 in a side view,
• 3 a schematic representation of a component according to the invention,
• 4 a time-voltage diagram to explain how the component according to the invention works and
• 5 a state diagram of the component according to the invention.

1 shows a schematic representation of a switching element 1 according to the invention with a sensor function section 2 in a plan view. The sensor function section 2 is formed by a metal coating 3 . The metal coating 3 is applied flatly to a plastic body 4 of the component 1 . A surface of the plastic body 4 has an insulating section 5 . The insulating section 5 is not covered by the metal coating 3 . The sensor function section 2 is thus isolated from other sections of the metal coating 3 . The sensor function section 2 forms an electrode surface 6 and a supply line 7 which is electrically conductively connected to the electrode surface 6. The electrode surface 6 is suitable as a capacitive sensor. An electrical potential of the electrode surface 6 can be tapped off via the feed line 7 . The metal coating 3 has been applied to the plastic body 4 by electroplating.

2 shows a schematic representation of the switching element 1 according to FIG 1 in a side view. A colored plastic cover plate 8 is attached to the plastic body 4 of the switching element 1 and forms a decorative touch surface of the switching element 1 . The metal coating 3 is applied to the plastic body 4 opposite to the touch surface.

3 shows a schematic representation of a component 9 according to the invention. A switching element 1 of the component 9 has a plastic body 4 and a metal coating 3 . An outside touch surface of the switching element 1 is formed directly by the plastic body 4 . The plastic body 4 consists of a translucent plastic. The metal coating 3 arranged on the rear of the plastic body 4 creates an in 3 not visible sensor function section formed with an electrode surface. A light source 10 , which is an LED spotlight, is positioned facing the metal coating 3 .

A housing 11 of the component 9 carries both the switching element 1 and the lighting means 10. On the inside of the housing 11 there is also a switching device 12 which is connected to the sensor function section and to the lighting means 10 via lines (not shown). If a finger is moved from the outside in the direction of the touch surface formed by the plastic body 4, then the capacitance of the electrode surface changes. The switching device 12 detects this and then switches the light source 10 on. The component 9 shown can form part of a body of a vehicle, for example.

4 shows a time-voltage diagram 13 to explain how the component according to the invention works. The time-voltage diagram 13 has a voltage axis 14 and a time axis 15 . A switching device of the component applies a voltage to an electrode surface of a switching element of the component. A first voltage curve 16 represents this voltage in the time-voltage diagram 13. At the same time, the switching device carries out a voltage measurement on the electrode surface. A voltage measured in this way is represented by a second voltage curve 17 . A charging time 18 of the electrode surface can be read from the second voltage curve 17 . The charging time 18 depends on an inherent capacity of the electrode surface. The self-capacitance of the electrode surface changes when a finger approaches the electrode surface. The switching device can thus determine the intrinsic capacitance of the electrode surface, ie determine from a capacitance value and/or a change in the intrinsic capacitance whether and how the switching element is actuated. In response to this, the switching device can output control signals.

5 shows a state diagram of the component according to the invention. In an off state 19, the lighting means of the component is switched off. A user now approaches his finger to the touch surface. At a point in time at which the user's finger has not yet touched the touch surface, a change in capacitance is already detected by the switching device. A change is now made to an illumination state 20 in which the switching device activates the lighting means. The switching element is backlit. Due to a gap in the electrode surface, an area of the touch surface now lights up. The user can thus see that his finger is located over an area of the touch surface in which the switching element can be actuated. The user now moves his finger even closer to the touch surface and touches it. The capacitance changes even further, so that the switching device of the component controls an actuator that is connected to the component. The component is now in an activation state 21. Alternatively, in the lighting state 20, the user could decide to withdraw his finger again, so that the component returns to the off state 19 and the lighting means is deactivated again.

The present invention is not limited to the illustrated embodiments. Modifications within the scope of the protection claims are just as possible as a combination of the features, even if they are shown and described in different exemplary embodiments.

Reference List

1

switching element

2

sensor function section

3

metal coating

4

plastic body

5

insulation section

6

electrode area

7

supply line

8th

plastic cover plate

9

component

10

bulbs

11

Housing

12

switching device

13

Time-Voltage Diagram

14

tension axis

15

timeline

16

First tension curve

17

Second tension curve

18

charging time

19

off state

20

lighting condition

21

Activation State

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 202019103960 U [0002]
• EP 2388920 A [0003]
• TW 200951546 A [0004]
• DE 2545371 B1 [0004]

Claims (24)

Switching element (1) with a plastic body (4), the switching element (1) forming a touch surface, the switching element (1) having a metal coating (3) with which a surface of the plastic body (4) is coated, and the metal coating (3) is at least partially produced by electroplating, characterized in that the surface faces away from the touch surface of the switching element (1). Switching element (1) after claim 1 , characterized in that the plastic body (4) is formed from a material comprising an acrylonitrile-butadiene-styrene copolymer and/or a polycarbonate. Switching element (1) after claim 1 , characterized in that the plastic body (4) is formed by a transparent or a semi-transparent plastic material. Switching element (1) according to one of the preceding claims, characterized in that the touch surface is formed by a colored plastic cover plate (8), by a transparent plastic cover plate (8) or by a lacquer coating. Switching element (1) according to one of the preceding claims, characterized in that the metal coating (3) on the plastic body (4) forms a sensor function section (2) which is electrically insulated from other sections of the metal coating (3), the sensor function section (2 ) has an electrode surface (6), and wherein the switching element (1) has a lead (7) which is electrically conductively connected to the electrode surface (6). Switching element (1) after claim 5 , characterized in that the supply line (7) is formed by the sensor function section (2). Switching element (1) after claim 5 or 6 , characterized in that the sensor function section (2) is electrically insulated from the other sections of the metal coating (3) by an insulating section (5) of the surface of the plastic body (4). Switching element (1) according to one of Claims 5 until 7 , characterized in that the electrode surface (6) has a surface area of at least 0.2 cm ² . Switching element (1) according to one of Claims 5 until 8th , characterized in that the supply line (7) is a strip conductor with narrow dimensions relative to the electrode surface (6). Switching element (1) according to one of Claims 5 until 9 , characterized in that the lead (7) has a width of 0.5 mm to 3 mm. Switching element (1) according to one of Claims 5 until 10 , characterized in that the supply line (7) has a width which is 0.01% to 100% of a maximum diameter of the sensor function section (2). Switching element (1) after Claims 5 until 11 , characterized in that the switching element (1) has a marking in or on the touch surface, which is arranged in alignment with the electrode surface (6). Switching element (1) after claim 12 , characterized in that the marking is an optical marking which is formed by an imprint on the touch surface, by a transparent or semi-transparent section of the touch surface and/or by a recess in the touch surface. Switching element (1) according to one of the preceding claims, characterized in that the metal coating (3) has at least one viewing window. Switching element (1) according to one of Claims 5 until 13 , characterized in that the metal coating (3) has at least one viewing window which is arranged in the electrode surface (6). Component (9) comprising the switching element (1) according to one of Claims 5 until 13 or after claim 15 , further comprising a switching device (12), wherein the switching device (12) is coupled to the supply line (7) of the switching element (1), and wherein the switching device (12) is set up to determine a capacitance and depending on the determined Capacity to output control signals. Component (9) after Claim 16 , characterized in that the component (9) electrically insulates the touch surface from the metal coating (3). Component (9) after Claim 16 or 17 , characterized in that the component (9) has a housing (11) in which the switching element (1) is enclosed, so that the metal coating (3) is electrically insulated from the sensing area. Component (9) according to one of Claims 16 until 18 , characterized in that the component (9) has a lighting means (10). Component (9) after claim 19 , characterized in that the lighting means (10) is arranged on a side of the switching element (1) which faces away from the touch surface of the switching element (1). Component (9) according to one of claims 19 or 20 , characterized in that the switching device (12) is coupled to the lighting means (10), the switching device (12) being set up to control the lighting means (10) as a function of the capacitance determined. Component (9) after Claim 21 , characterized in that the switching device (12) is set up to turn on the lighting means (10) when a finger enters a region close to the electrode surface (6). Component (9) after Claim 22 , characterized in that the switching device (12) is set up to switch off the lighting means (10) when the finger leaves the vicinity of the electrode surface (6). Component (9) after Claim 21 , characterized in that the switching device (12) is set up to control a functional unit when a finger is moved so close to the electrode surface (6) that it touches the touch surface.

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