Control unit for underwater use and method for its manufacture

Abstract

Operating unit (1) for underwater use, comprising a front plate (2) made of glass and electrical sensor elements (24) for evaluating an electrical capacitance, and a control unit, wherein a fired ceramic conductive paste is applied to the front plate (2) and / or an optionally present sensor plate (7), characterized in that the control unit is configured to detect touches and approaches of a person to the operating unit (1) and to trigger an action in response thereto when the operating unit (1) is underwater, wherein the operating unit (1) is a capacitive operating unit, wherein the electrical sensor element (24) is formed by an electrically conductive coating, and wherein the operating unit (1) comprises at least two electrical sensor elements (24) designed as a sensor button and / or slider, which are connected to a microcontroller,wherein the sensor button and / or slider react to a touch or approach by the person with a change in capacitance, and the control unit is designed to infer from the extent (sensor stroke) of the change in capacitance and its temporal change in at least two sensor elements (24) a touch or approach by the person and also to detect whether the capacitive operating unit (1) is in contact with water or outside of water.

Description

[0001] The invention relates to an operating unit for underwater use and a method for its production. In particular, the invention relates to an operating unit for underwater use, comprising a glass front panel and electrical sensor elements for evaluating electrical capacitance, which can be arranged on a sensor plate, and a control unit, wherein a fired ceramic conductive paste is applied to the front panel and / or the sensor plate, as well as a preferred method for its production.

[0002] Control units, especially so-called touchscreens, are being used more and more frequently in various areas, such as as control panels for household appliances, machines and systems, and for small electrical devices such as computers, telephones, and the like. In particular, control units using "projected capacitive touch" (PCT) technology have been increasingly used in recent years. This technology enables touch recognition through a protective screen in front of a display. Such PCT touchscreens can be weatherproof, making them particularly suitable for outdoor use. However, such control units have not yet been used underwater, as the evaluation of touches underwater was considered very difficult.Therefore, no control units for underwater operation are known which, for example, in a swimming pool, can trigger the execution of various actions via a person touching or approaching the control unit.

[0003] The publication "Touché: Enhancing Touch Interaction on Humans, Screens, Liquids, and Everyday Objects" by Munehiko Sato, Ivan Poupyrev, and Chris Harrison (see: https: / / www.disneyresearch.com / publication / touche-enhancing-touch-interaction-onhumans-screens-liquids-and-everyday-objects / ) deals with the detection of touches on an underwater control unit. The core of the technology described is a new "swept frequency capacitive sensing technique," which is based on sweeping a frequency spectrum. This should enable not only the detection of touch but also the recognition of complex configurations of the human hand and body. One or more sensor electrodes can be used. The article highlights that in a typical touch sensor, a conductive object is excited by an electrical signal of a fixed frequency, but this has disadvantages.Regarding water, this article only mentions that the sensor can be used to determine whether someone is touching or immersing themselves in water, for example. The section "Sensing Gestures in Liquids" emphasizes that interacting with water does not mean using touchscreens underwater, but rather touching the water itself.

[0004] Publication US 2012 / 0 256 867 A1 describes an underwater touchscreen system comprising an enclosure containing an internal space and a window surface; a digital device containing a capacitive touchscreen display disposed within the internal space of the enclosure, wherein the capacitive touchscreen display is adjacent to the window surface of the enclosure. An inner membrane and an outer membrane are also described. Furthermore, a fluid with a comparatively low dielectric constant is used to compensate for adverse effects of water for the evaluation of capacitive signals.

[0005] Publication DE 100 11 229 B4 describes a capacitive touch sensor that is particularly useful in the sanitary sector. It addresses the particular difficulties associated with using capacitive sensors in contact with water. According to the publication, such capacitive sensors are said to be highly susceptible to interference from electrostatic discharges, electromagnetic radiation, and extremely sensitive to changes in the dielectric constant in surrounding media, e.g., due to moisture, wetting, or water vapor. This is why they are said to be of limited use, particularly in the sanitary fittings sector, even when appropriately complex control electronics are provided. Furthermore, this publication details the precise electronic design of this touch sensor. This illustrates that a person skilled in the art would be discouraged from using capacitive sensors in underwater applications, for example.

[0006] The publication WO 2017 / 167818 A1 deals with the robustness of capacitive sensors in water and the detection of touches, whereby in particular the functionality of the processor used is described in some detail.

[0007] In control units, the sensor electrodes are typically located on a sensor substrate, such as a glass or plastic. A glass substrate's transparency not only allows it to be placed in front of a display, but its dielectric properties also meet all the requirements placed on printed circuit boards for electronic circuits with high integration density and ultra-high frequencies.

[0008] In addition, PCT control units in particular often contain separate sensor layers for detection along the X-axis and the Y-axis, allowing the touch position to be determined not only in small, predefined sensor fields, but across the entire area. This sensor layer is usually formed by an indium tin oxide (ITO) coating, which is structured accordingly in the X- or Y-direction. Depending on the layout, additional metallic conductive structures such as conductor tracks and resistors are also arranged.

[0009] EP 2 439 622 A1 discloses an operating and monitoring device with two touch-sensitive sensors, which can be configured such that two glass panes are connected to each other via spacers and coated with ITO on the facing surfaces. The glass pane facing the person with its non-ITO-coated side can, for example, be designed as a thin glass pane, with the ITO layer applied to the thin glass pane serving both as a sensor for the capacitive touch sensor and as a layer for the resistive touch sensor.

[0010] However, the disadvantage here is that the structuring of the metallic conductive structures using thin-film technology or photolithography usually requires a vacuum and is therefore complex and expensive.

[0011] Publication DE 10 2013 215 060 A1 describes a capacitive sensor device comprising, among other things, a glass front plate and an electrically conductively coated thin-glass sensor plate. A ceramic conductive structure made of a fired ceramic conductive paste is arranged on the sensor plate. The capacitive sensor device is intended to combine broad applicability with simple and cost-effective production and is intended to be used in many areas, for example, for sensor devices using PCT technology, for outdoor applications, or for other areas where robust designs are required. The use of a thin-glass plate as the sensor plate enables very thin sensor devices in the overall structure, which are also lightweight.At the same time, the use of a fired ceramic conductive paste to form the conductive structures should ensure excellent adhesion of the conductive structures to the thin glass substrate as well as high resistance to environmental influences, UV radiation and chemical influences.

[0012] The publication US 2016 / 0 334 935 A1 discloses an operating method for an electronic device, comprising: determining whether an environment of a touchscreen panel has changed from a first environment to a second environment; and if so, changing a reference voltage of the touchscreen panel from a first to a second value. In one embodiment, the first environment is an environment in air and the second environment is an environment in water. The operating method and electronic device are described, for example, in Fig. 7 and Fig. 9 of US 2016 / 0 334 935 A1.

[0013] The publication WO 2015 / 088453 A1 describes a touchscreen for underwater use, i.e. a transparent screen placed over an existing capacitive type touchscreen, wherein the touchscreen according to the invention is used for touch input under conditions of increased pressure, underwater or when using protective equipment such as gloves, and the touchscreen according to the invention does not have an electrical energy source, wherein the touchscreen is a capacitive touchscreen in the outward direction, consisting of at least: - a lower foil metallized with an electrically conductive and transparent material so that it forms fields, - a frame connecting a lower foil and an upper foil and containing a medium, - spacers between the bottom film and the top film, the spacers being glued to the underside of the top film or to the top side of the bottom film or to both, - an upper foil metallized with an electrically conductive and transparent material to form a grid.

[0014] Against this background, the object of the invention was to provide an operating unit for use under water, the design of which enables a high level of durability and thus a wide range of applications and which is at the same time simple and cost-effective to manufacture.

[0015] The object of the invention was also to provide a method for producing such an operating unit.

[0016] This object is achieved according to the invention by an operating unit and a method for its production having the features of the corresponding independent patent claims. Preferred embodiments of the operating unit according to the invention are listed in the corresponding dependent patent claims. Preferred embodiments of the operating unit according to the invention correspond to preferred embodiments of the method according to the invention, and vice versa, even if this is not explicitly stated herein.

[0017] The subject matter of the invention is therefore an operating unit for underwater use, comprising a front plate made of glass and electrical sensor elements for evaluating an electrical capacitance, and a control unit, wherein a fired ceramic conductive paste is applied to the front plate and / or an optionally present sensor plate, wherein the control unit is configured to detect touches and approaches of a person to the operating unit and to trigger an action in response thereto when the operating unit is underwater, the operating unit is a capacitive operating unit, wherein the electrical sensor element is formed by an electrically conductive coating, and wherein the operating unit comprises at least two electrical sensor elements which are designed as a sensor button and / or slider which are connected to a microcontroller,wherein the sensor button and / or slider react to a touch or approach by a person with a change in capacitance, and the control unit is designed to infer a touch or approach by a person from the extent (sensor stroke) of the change in capacitance as well as its temporal change in at least two sensor elements and also to detect whether the capacitive control unit is in contact with water or outside of water.

[0018] At this point it should be noted that the wording “for use under water” also means in particular that the invention also includes the use of the control unit described herein for use under water.

[0019] The term "detection of a person's touches and approaches to the control unit" is to be interpreted broadly herein. In particular, "approaches of a person" also include a simple approach or the execution of gestures by a person in front of the control unit, in particular at a distance of less than 50 cm, more preferably less than 20 cm, from the control unit, whereby different gestures can represent different inputs.

[0020] The term "underwater use" should be understood broadly. Examples of applications for the control unit include a swimming pool, whether indoor or outdoor, or a large aquarium in which divers or animal keepers also operate.

[0021] In a preferred embodiment of the operating unit, a structured, substantially transparent, electrically conductive layer is arranged on the front panel and / or a sensor plate.

[0022] Furthermore, according to the invention, an operating unit is preferred in which electrical sensor elements are placed on the front plate and / or a sensor plate, wherein a ceramic conductive structure made of a fired ceramic conductive paste is arranged on the front plate and / or the sensor plate on which sensor elements are placed.

[0023] Preferably, the baked ceramic conductive paste in the control unit contains at least 50 wt.% silver.

[0024] According to the invention, an operating unit is preferred in which at least one electrical sensor element is arranged on the front panel.

[0025] In a particularly preferred embodiment of the control unit according to the invention, the front panel is designed such that at least one of the locations on or behind the front panel where a sensor element is located differs haptically from the surroundings of this location. This location, for example in the form of a circle, an ellipse, or a bar, can be a depression or elevation, for example, or can have a specific coarser or finer surface structure.

[0026] The control unit has electrical sensor elements. Electrical sensor elements are generally based on the evaluation of changes in electrical resistance or capacitance. The present invention concerns changes in electrical capacitance. Electrical sensor elements can also be referred to as sensor electrodes.

[0027] In the present invention, the operating unit is a capacitive operating unit, with a sensor element formed by an electrically conductive coating. Herein, a capacitive operating unit generally refers to an operating unit in which an electrical signal caused by changes in electrical capacitance can be generated by the approach and / or contact of an object, such as a hand, a finger, a pen, or the like, to sensor electrodes. Generally, the front panel faces the person, so that the approach and / or contact occurs on the front panel.

[0028] The operating unit according to the invention comprises at least two electrical sensor elements which are designed as a sensor button and / or slider which are connected to a microcontroller, wherein the sensor button and / or slider react to a touch or approach by a person with a change in a capacitance and the control unit is designed to infer a touch or approach by a person from the extent (sensor stroke) of the change in the capacitance as well as its change over time in at least two sensor elements and also to detect whether the capacitive operating unit is in contact with water or outside of water.

[0029] According to the invention, the inputs on the keys of a capacitive operating device can be evaluated in such a way that, for example, a finger press, a palm resting on the key, or an approach with the back of the hand can be detected even underwater. In this case, one or more key surfaces (e.g., as a circuit board on glass) are connected to a microcontroller. These surfaces can have the same or different geometries. The microcontroller then measures the capacitance of the key surfaces, usually several times per second, and evaluates the measured signal to detect actuation.

[0030] Preferably, each sensor element (sensor button and each linear slider (at least 2, usually 5 or more segments)) represents an element of the control unit to be evaluated. These sensor elements are preferably evaluated sequentially. A single sampling frequency is advantageous. Evaluation criteria such as absolute signal strength, the relative signal strength of the elements to each other, and the temporal progression of the signals are generally used for evaluation. A design for different water types (tap water, bathing water with care additives, chlorinated water, salt water) is also possible.

[0031] Preferably, in a method for operating the capacitive operating unit according to the invention for detecting a finger underwater, not only the positive sensor displacement of the surface is evaluated, but also the temporal progression of the change in both the positive and negative directions. Preferably, the behavior of the sensor surfaces relative to one another is evaluated. This is advantageous because water behaves differently than air with regard to the propagation of the electric field.

[0032] The control units according to the invention can be designed for different water types, including tap water, bathing water with care additives, and chlorinated water. These differences can be taken into account, in particular, by adapted software stored in the control unit's control system.

[0033] To ensure that the control unit does not malfunction even under extreme conditions, the control unit or its control unit can preferably be designed in such a way that the control unit deactivates itself when it no longer detects water or re-parameterizes itself so that it can also be used above water.

[0034] According to the invention, at least one ceramic conductive structure is preferably arranged on each side of an optionally used sensor plate. Particularly preferably, the operating unit contains a sensor plate.

[0035] According to the invention, the front panel is made of glass. This has the advantage that the structure of the control unit can be located behind the front panel, as seen from a person, and the control unit can be designed to be visually appealing thanks to the front panel. Furthermore, glass offers good weather resistance and thus ensures the protection of the control unit. For this purpose, the front panel generally has a thickness of 1 to 10 mm, preferably 2 to 5 mm, and particularly preferably 3 to 4 mm. Furthermore, such a front panel can easily support the structure of the control unit and, if necessary, other components. Float glass is preferably used for the front panel.

[0036] Glass is also easy to clean, which allows it to be used in areas where frequent cleaning is necessary, particularly in areas where good hygiene is important. Furthermore, transparent and non-transparent areas can be created on glass, with transparent areas being particularly advantageous for enclosing the control unit with a display. For example, lighting devices such as light-emitting diodes can be attached to the front panel. Furthermore, the front panel can advantageously be anti-reflective and preferably have an ESD protective layer to prevent electrostatic discharge (ESD). The front panel preferably has a thickness in the range of 1 mm to 10 mm.

[0037] The front panel preferably has at least one transparent area, in particular a plurality of transparent and non-transparent areas. Particularly preferably, the sensor area of ​​an optionally provided sensor plate is arranged, as seen from a person, essentially behind the part of the front panel having transparent areas. Evaluation electronics for the electrical signals from the electrical sensor elements, e.g., sensor electrodes, are advantageously arranged behind a non-transparent area. Very particularly preferably, as seen from the person, a display is arranged behind the control unit in transparent areas of the front panel.

[0038] The evaluation electronics are preferably arranged or at least connected to a first surface of the front panel. Generally, the first surface of the front panel is the surface of the front panel facing away from the person. Thus, the evaluation electronics are preferably located on the side of the front panel facing away from the person.

[0039] The term “evaluation electronics” encompasses electronic components, conductor track structures, soldered connections, and possibly other components. The evaluation electronics can, for example, be arranged directly on the front panel, on a flex cable, or on a separate circuit board. If a separate circuit board is used, this can in turn be arranged on the first surface of the front panel. In this case, the circuit board has a first and a second side, with conductor track structures, soldered connections, electronic components, and possibly also other components, being arranged on the first side of the circuit board. The circuit board can also have two or more layers, preferably four layers. Advantageously, the second side, i.e. the side without the components mentioned, is attached to the front panel, in particular to its first side, in a suitable manner. The capacitive operating unit according to the invention preferably does not have a separate circuit board.

[0040] A sensor plate optionally used in the control unit is preferably made of glass with a thickness in the range of 0.2 to 2.0 mm, preferably in the range of 0.3 to 1.5 mm, particularly preferably in the range of 0.5 to 1.1 mm, and most preferably in the range of 0.7 to 1.1 mm. It is preferred that at least one spacer is arranged between the front plate and the sensor plate, and that a ceramic conductive structure of the sensor plate is contacted via at least one spring contact.

[0041] The thickness of the sensor plate is the thickness without any coating. The structure of the control unit according to the invention can thus be kept thin. Any possible parallax error, for example, in the presence of a display arranged behind the control unit, remains small. Furthermore, in embodiments in which the sensor plate has electrically conductive layers on both surfaces, it is advantageous for the distance between these electrical layers to be small. The sensor plate can also advantageously be anti-reflective.

[0042] Preferably, at least one ceramic conductive structure made of a fired ceramic conductive paste is arranged on the sensor plate. The term “conductive structure” is understood here to mean a structure or a pattern of electrically conductive elements, for example conductor tracks and resistors. The conductive structure preferably comprises, in particular, conductor tracks that have the lowest possible resistance, advantageously including pads, e.g. soldering pads and connection pads. A further layer can be present between the conductive structure and the sensor plate, for example an insulating layer or a layer that improves the melt connection. Preferably, however, the conductive structure is arranged at least partially directly on the sensor plate, i.e. without other materials being arranged between the conductive structure and the sensor plate. However, it is preferably not excluded that the conductive structure can also be arranged partially not directly on the sensor plate.Depending on the layout, crossings or tunnels may also occur.

[0043] The ceramic conductive structure is formed from a fired ceramic conductive paste. "Ceramic conductive structure" refers in particular to an inorganic conductive structure. Such a ceramic conductive structure, formed from a fired ceramic conductive paste, exhibits high durability and good adhesion to the front panel or sensor plate. Furthermore, a solder connection can be applied to it.

[0044] “Ceramic conductive paste” is understood to be a fireable paste that generally contains both a ceramic component and a metal component. Such pastes are known, for example, in the field of thick-film technology (also known as “thick-film technology”). In addition to the ceramic component and the metal component, such fireable pastes generally contain further additives such as a solvent, for example at least one alcohol such as terpineol, which influences the rheology of the paste. This is particularly important when the paste is applied using a printing process. In the fireable paste, the proportion of the ceramic component is preferably 10-30 wt.%, the proportion of metal particles, which preferably have a grain size of no more than 15 µm, in particular silver particles, is 60-90 wt.%, preferably 70-85 wt.%, and the proportion of solvent is 5-10 wt.%, in each case based on the total conductive paste.The ceramic conductive paste can be low-melting or high-melting. A low-melting paste is used here with a melting point of 500-600°C, preferably 500-540°C, and a high-melting paste is used here with a melting point of 600-700°C, preferably 650-680°C.

[0045] The ceramic component of the conductive paste ensures its adhesion to the glass substrate, i.e., the front and / or sensor plate. During firing, the ceramic portion of the ceramic conductive paste applied to the substrate can fuse with the surface of the thin glass sensor plate, creating a strong bond between the ceramic conductive paste and the front and / or sensor plate. This ensures particularly good adhesion to the glass substrate. It also enables high resistance to environmental influences such as UV radiation and, for example, adhesives used during further processing.

[0046] The ceramic component generally consists of inorganic, non-metallic materials, which are usually crystalline and contain metallic and non-metallic elements. The ceramic component is preferably glass frit. The expansion coefficient and melting range of the glass frit are advantageously adapted to the carrier substrate. Metal oxides, metal nitrides, metal carbides, or a mixture of these materials are generally particularly suitable as ceramic components. The ceramic component is usually in powder or dispersed form.

[0047] The metal component of the conductive paste ensures the highest possible conductivity. Accordingly, the conductive paste should contain highly conductive materials. Precious metals such as silver, gold, platinum and palladium are particularly preferred as metal components. Silver conductive paste is particularly preferred as a ceramic conductive paste. The precious metals mentioned can be used individually or in combination. Alloys of precious metals, for example gold or silver with platinum or palladium, can also be used. The advantage of precious metals as a metal component is that they do not have to be fired in a protective atmosphere. Furthermore, non-precious metals can also be used as metal components, as long as good conductivity and durability are guaranteed. These metals can also be used individually, in combination or as alloys, both with each other and with precious metals.For conductive pastes containing non-precious metals, those containing copper are preferred.

[0048] In ceramic conductive pastes, the average diameter of the metal particles is generally no more than 15 µm, preferably from 1 to 15 µm. The ceramic conductive paste particularly preferably contains silver particles. In the fired ceramic conductive paste, the metal particles are generally in contact with each other in such a way that a continuous electrically conductive structure is formed.

[0049] Generally, the width of the ceramic conductive structure made from a fired ceramic conductive paste is no more than 1 mm, preferably no more than 0.3 mm, and particularly preferably no more than 0.2 mm. The thickness (height) of the ceramic conductive structure made from a fired ceramic conductive paste is preferably no more than 30 µm, particularly preferably no more than 20 µm. In this way, a particularly thin control unit can be achieved.

[0050] The operating unit generally has sensor electrodes, as it is designed as a capacitive operating unit. According to the invention, these can be formed, in particular, like the ceramic conductive structure, from a fired ceramic conductive paste or consist of a substantially transparent, electrically conductive layer.

[0051] In a preferred embodiment of the operating unit, an essentially transparent, electrically conductive layer, which is preferably structured, is therefore additionally arranged on the front panel and / or the sensor plate.

[0052] "Substantially transparent" means that the electrically conductive layer is at least 80% transparent to electromagnetic waves, particularly in the visible light range. In particular, "substantially transparent" also means that the electrically conductive layer appears transparent to the viewer of the control unit. This can be achieved by selecting appropriate materials, such as indium tin oxide (ITO), or by suitable structuring, such as with silver nanowires, which are so thin that they are not perceptible to the viewer.

[0053] This can be, for example, floated or drawn glass. The use of such a sensor plate has the advantage that, thanks to the UV resistance of glass, the control unit according to the invention can also be used outdoors. In particular, this enables very thin control units that have a low overall weight and thickness.

[0054] The essentially transparent, electrically conductive layer is preferably structured, particularly if it is present as a uniform layer on a front panel or sensor plate, with the structuring being carried out, for example, via an etching or laser ablation step. The structuring is generally carried out according to the function of the electrically conductive layer, for example as a sensor electrode or as a conductor track for contacting, with a essentially transparent, electrically conductive layer structured as a sensor electrode being preferred. The sensor electrodes can have a variety of shapes, from simple geometric shapes such as circles, rectangles, etc., to complex irregular shapes. Lines of an electrically conductive material in the X and Y directions are preferred.The lines in the X direction can be separated from the lines in the Y direction in several electrically conductive layers, or they can be arranged together in a single electrically conductive layer, for example, in a grid-like arrangement. For example, an electrically conductive layer can be present on a first surface of the front panel or a sensor plate, and / or an electrically conductive layer can be present on a second surface of the sensor plate.

[0055] The substantially transparent, electrically conductive layer is generally a semiconductor oxide layer or printable electronics such as silver nanowires. A substantially transparent, electrically conductive semiconductor oxide layer preferably contains or consists of ITO, zinc oxide, antimony-doped tin(IV) oxide (ATO), aluminum-doped zinc oxide (AZO), or fluorine-doped tin(IV) oxide (FTO). Preferably, the substantially transparent, electrically conductive semiconductor oxide layer is structured, for example, to be used as a capacitive sensor electrode.

[0056] Generally, the essentially transparent, electrically conductive layer is created on the sensor plate by sputtering. Other manufacturing methods are possible. For example, a film of an electrically conductive material can be applied to the sensor plate using a suitable printing process, e.g., screen printing, and then fired. For example, thin glass plates with an ITO coating on one or both sides are also commercially available. For example, ITO-coated glass can be obtained directly from float glass production.

[0057] Particularly preferably, the substantially transparent, electrically conductive semiconductor oxide layer on the sensor plate comprises indium tin oxide (ITO). For example, an ITO coating is patterned according to the shape of the desired sensor electrodes using an etching or laser ablation step, for example, to obtain lines in the X and / or Y directions.

[0058] If present in the embodiment as a capacitive operating unit, the essentially transparent, electrically conductive layer is preferably electrically conductively connected to the ceramic conductive structure, so that electrical signals can be conducted from the essentially transparent, electrically conductive layer via the ceramic conductive structure and preferably via a further element, such as a flexible cable, a spring contact or a metal clamp, to the evaluation electronics. The corresponding electrical signals, for example from the X and Y lines of the sensor electrodes, are preferably conducted via the conductive structures made of fired ceramic conductive paste on the sensor plate to a connection on the sensor plate, e.g. to a flexible cable or a spring contact, via which they can be further conducted to the evaluation electronics, which are usually not located on the sensor plate.

[0059] Preferably, the at least one ceramic conductive structure and the substantially transparent, electrically conductive layer are arranged on a first surface of the optionally used sensor plate facing the front plate. This has the advantage that the distance between the second surface of the front plate, on which in particular a person makes contact, and the sensor electrodes is kept very small, thereby achieving a very precise representation of the contact. If more than one substantially transparent, electrically conductive layer and / or ceramic conductive structure made of a fired ceramic conductive paste is arranged on the first surface of the sensor plate facing the front plate, these can optionally be arranged separately from one another by applying suitable, generally insulating layers between the electrically conductive layers. Such layers are, for example,Those made of printed thick-film insulating pastes, silicon dioxide (SiO2)-containing layers, which are preferably sputtered on, or films made of a plastic or a ceramic, with SiO2 layers being preferred. However, preferably, exactly one substantially transparent, electrically conductive layer and / or ceramic conductive structure made of a fired ceramic conductive paste is arranged on the first surface of the sensor plate facing the front plate.

[0060] In a particularly preferred embodiment of the invention, the operating unit has a lighting unit which contains at least one light-emitting diode, for example. According to the invention, it is preferred that a housing is arranged on a first surface of the front panel which faces the interior of the operating unit and is at least partially coated with at least one opaque layer, the inner surface of which housing can at least partially reflect light rays; and at least one light-emitting means arranged in a space between the housing and the first surface of the front panel, wherein light rays generated by the light-emitting means can at least partially penetrate the front panel. Preferably, at least part of the inner surface comprises a diffusely reflecting surface.

[0061] In a preferred embodiment of the capacitive operating unit, at least one ceramic conductive structure is arranged on each side of the sensor plate. Preferably, at least one substantially transparent, electrically conductive layer is additionally arranged on each side of the sensor plate. The at least one ceramic conductive structure and optionally also the at least one electrically conductive layer on the first surface facing the front plate and the at least one further ceramic conductive structure and optionally also the at least one further electrically conductive layer on the second surface facing away from the front plate are separated from one another by the sensor plate.Preferably, a substantially transparent, electrically conductive layer on the first surface facing the front panel comprises lines of conductive material in the X-axis direction and a further substantially transparent, electrically conductive layer on the second surface facing away from the front panel comprises lines of conductive material in the Y-axis direction or vice versa.

[0062] Generally, the sensor plate is arranged facing the first surface of the front panel. This means that the sensor plate is generally arranged behind the front panel as seen from the person's perspective. Advantageously, the evaluation electronics are also arranged on the first surface of the front panel, so that any sensor plate used faces the side of the front panel with the evaluation electronics, enabling a favorable connection between the sensor plate and the evaluation electronics.

[0063] The optional sensor plate or front panel can be connected to the evaluation electronics in a variety of ways. For example, such a connection can be made via a spring contact or a flexible cable.

[0064] In a preferred embodiment, the capacitive operating unit as a preferred embodiment of the invention therefore has a front plate made of glass and a sensor plate made of thin glass, on which a ceramic conductive structure made of a fired ceramic conductive paste and a structured, essentially transparent, electrically conductive layer is arranged, (a) wherein the glass sensor plate faces a first surface of the front panel; (b) an evaluation electronics for the electrical signals is arranged directly or via a printed circuit board on the first surface of the front panel; and (c) the at least one electrically conductive layer is connected to the evaluation electronics via at least one spring contact.

[0065] Preferably, the spring contact is attached to the sensor plate via a clip connection. Generally, the spring contact can also be connected to the ceramic conductive structure by soldering, for example.

[0066] According to an even more preferred embodiment of the invention, the conductive structures on the sensor plate are contacted via a flex cable. The flex cable is typically a flat-flex cable, with "flat-flex cable" particularly including FFC (flat flex cable) and FPC (flexible printed circuit) types. The flat-flex cable is generally a multi-core cable in which the cores are not bundled in a circle, but rather run next to one another—usually parallel. The flex cable generally has several cores; preferably, the flex cable has at least 5 cores, particularly preferably at least 10 cores. The spacing between the cores is typically 0.5 to 2.54 mm, preferably 1.27 mm.

[0067] The flex cable can be connected to the sensor plate in various ways, for example, using an anisotropically conductive adhesive. The flex cable is preferably soldered to the optional sensor plate, in particular to the ceramic conductive structure on the sensor plate. In particular, the use of a ceramic conductive structure, unlike, for example, organic lacquers, enables a soldered connection. In this preferred embodiment, the flex cable is thus fixed to the sensor plate using a solidified solder paste. The soldering process can be performed in various ways, for example, as a hot-bar soldering process. However, a reflow soldering process is preferred. The large number of wires in the flex cable and their comparatively close spacing require a precise soldering process.Soldering connects the flex cable to the ceramic conductive structure on the sensor plate via a permanently stable solder joint, ensuring high durability and, in conjunction with the conductive structure made of ceramic conductive paste, optimally implemented via appropriate solder pads. Furthermore, the solder joint, in conjunction with the ceramic conductive structures, allows for a completely inorganic control unit.

[0068] Evaluation electronics for detecting a person's touch or proximity can be located directly on the front panel, on the flex cable, or on a separate circuit board. For example, the evaluation electronics can be located on the flex cable using chip-on-flex (COF) technology.

[0069] Particularly preferred is an embodiment which has at least one ceramic conductive structure on each side of the sensor plate, and wherein the ceramic conductive structures arranged on both sides of the sensor plate are contacted via a single flexible cable. Here, too, the flexible cable preferably connects the ceramic conductive structures of the sensor plate to the evaluation electronics. This makes it possible, for example, for the sensors arranged on one side of the sensor plate in the X direction and the sensors arranged on the other side of the sensor plate in the Y direction to be combined into a connection for a single flexible cable by the ceramic conductive structures, which are formed from a fired-in ceramic conductive paste. The low thickness of the thin-glass sensor plate is advantageous here. Using a single flexible cable saves material and enables faster assembly.

[0070] Furthermore, it is preferred that the operating unit comprises a plurality of electrically conductive sensor layers. Particularly preferably, the operating unit has two, three, four, or five electrically conductive sensor layers. This enables a multi-layer sensor in which additional functions such as proximity detection, gesture recognition, etc., can be implemented via additional sensor layers.

[0071] Such a multilayer sensor thus has several sensor layers and, depending on the function and corresponding design, can also comprise several passivation layers and / or lacquer layers. In particular, several layers, which comprise conductive structures and / or a substantially transparent, electrically conductive layer, are separated from one another by insulating layers, for example, made of silicon dioxide.

[0072] In a preferred embodiment, the optional sensor plate is glued to the front panel. An adhesive layer is arranged between the sensor and front panels. A special adhesive is preferably used, particularly preferably an OC adhesive. The sensor plate, which may have a conductive structure and / or layer, is preferably glued to the front panel over its entire surface. The thickness of the adhesive layer is preferably 0.2 to 0.5 mm.

[0073] In a further embodiment of the capacitive control unit, at least one spacer is arranged between the front panel and the optionally present sensor plate. This embodiment is particularly preferred when contacting the conductive structures on the sensor plate is made via spring contacts. In this embodiment, the sensor plate is separated from the front panel by a distance defined by the at least one spacer. Thus, the at least one spacer can achieve a constant distance between the front panel and the sensor plate.

[0074] The spacer can be designed in various ways. However, components that can be assembled, such as SMD components, for example, zero-ohm resistors or capacitors or copper blocks, are preferred. These components can, for example, be attached to the front panel and / or to a circuit board belonging to the evaluation electronics during the assembly process, so that no separate work step is necessary to attach the spacers. Other spacer designs are also possible, such as plastic blocks. The connection between the spacers and the sensor plate is advantageously elastic in order to maximize the aforementioned advantages. For example, the connection is made using a suitable adhesive material, preferably an epoxy resin adhesive, which ensures elasticity.

[0075] The arrangement of the spacers is preferably such that the spacers are not visible to the person, for example in a non-transparent area of ​​the front plate and in the edge area of ​​the sensor plate.

[0076] In particular, when using a spacer in the embodiment as a capacitive operating unit, it is preferred that the distance between the front panel and the sensor plate be ≤ 1 mm, preferably ≤ 0.5 mm, particularly preferably ≤ 0.4 mm. A greater distance may, under certain circumstances, lead to losses in the accuracy of the touch signal registration by the sensor electrodes, parallax errors when the display is arranged behind the operating unit, and / or an undesirably thick overall structure of the operating unit. The distance is particularly preferably in the range of 0.2 to 0.35 mm.

[0077] Furthermore, in the embodiment of the operating unit according to the invention comprising spacers, it is preferred that a filler material is located in the space defined by the spacers between the front panel and the sensor panel. Such a filler material can, for example, be a suitable adhesive, such as an epoxy resin or an OC adhesive. An OC adhesive is preferably used here. The filler material has the advantage that it seals the space formed by the distance between the front panel and the sensor panel, so that no dirt can penetrate. On the other hand, particularly in large touchscreens with thin sensor glass, it is possible that vibrations of the glass panel caused by the touch can lead to inaccurate representation of the touch. This can be avoided by using a suitable filler material.

[0078] Particularly preferably, in the embodiment of the control unit according to the invention comprising spacers, the evaluation electronics are mounted directly on an uncoated or coated first surface of the front panel. Here, "mounted directly on an uncoated or coated first surface of the front panel" means that the evaluation electronics are not mounted on a printed circuit board. Thus, the glass front panel serves as the carrier material for the electronics. This eliminates the printed circuit board, enabling an advantageously low installation height of the control unit. Furthermore, the step of attaching the printed circuit board to the front panel is eliminated.

[0079] In a preferred embodiment of the capacitive operating unit, the first surface of the front panel is at least partially coated with one or more fired ceramic inks. Furthermore, a coating with a fired ceramic ink can also be present on the sensor plate. The fireable ceramic ink preferably has a firing temperature that differs by no more than 20°C from the firing temperature of the fireable ceramic conductive paste. This enables advantageous firing of the ceramic ink and conductive paste in one step. A coating with ceramic ink can serve as a decorative coating and / or to provide a non-transparent area. The coating can be applied in various ways, for example by applying a coating film or by suitable printing processes. Applying the coating by screen printing is particularly preferred.Ceramic and UV-stable screen printing inks are particularly preferred for coating.

[0080] Furthermore, it is preferred according to the invention that the front panel of the control unit is made of tempered single-pane safety glass. This creates a scratch-resistant surface and high mechanical strength. This also serves to protect the control unit. This enables a variety of underwater applications that require, for example, a robust surface for the control unit. In particular, a combination with the embodiment in which the conductor track structures of the evaluation electronics are applied to the uncoated or coated first surface of the front panel is suitable here. If such conductor track structures and / or decorative layers are fired into the glass front panel, this can be done by selecting a suitable firing temperature such that the glass front panel is simultaneously hardened into single-pane safety glass, i.e., without an additional process step.

[0081] A capacitive operating unit is preferred in which the coated first surface of the front panel is obtainable by simultaneously firing the ceramic colors and / or conductor track structures, for example at a temperature in the range of 600 to 700°C.

[0082] The invention also relates to a method for producing an operating unit for underwater use, comprising a front plate made of glass and electrical sensor elements for evaluating an electrical capacitance, and a control unit, wherein a fired ceramic conductive paste is applied to the front plate and / or an optionally present sensor plate, and wherein the control unit is configured to detect touches and approaches of a person and to trigger an action in response thereto when the operating unit is underwater, the operating unit is a capacitive operating unit, wherein the electrical sensor element for evaluating an electrical capacitance is formed by an electrically conductive coating, and wherein the operating unit comprises at least two electrical sensor elements designed as a sensor button and / or slider, which are connected to a microcontroller,wherein the sensor button and / or slider react to a touch or approach by a person with a change in capacitance, and the control unit is designed to infer from the extent (sensor stroke) of the change in capacitance and its temporal change in at least two sensor elements a touch or approach by a person and also to detect whether the capacitive operating unit is in contact with water or outside of water, the method comprising the following steps: (ii) applying a burnable ceramic conductive paste to the front plate and / or the sensor plate and (iv) Firing the ceramic conductive paste.

[0083] In a preferred embodiment of this process, the baking temperature in step (iv) is in the range of 500 to 700 °C.

[0084] The method of applying the fireable ceramic conductive paste to the front panel and / or the sensor plate in step (ii) is not particularly restricted according to the invention. However, it is preferred that the application in step (ii) be carried out using screen printing or inkjet technology. This has the advantage that commercially available fireable ceramic conductive pastes can be used, which are generally tailored to these processes. Screen printing is particularly preferred because it is an efficient and cost-effective process, particularly with regard to the equipment technology and the ceramic conductive pastes tailored to screen printing. If a particularly high resolution is required, for example with structures below 50 µm, inkjet technology is preferred, which, unlike screen printing, does not require masks and offers even better resolution.The application in step (ii) can also be carried out by other techniques, for example by laser-assisted digital printing processes such as LIFT technology, which is a nozzle-free and contactless process.

[0085] When applying the fireable ceramic conductive paste, a desired structuring can already be carried out, which can then be fixed during the subsequent firing of the ceramic conductive paste.

[0086] Following the application of the fireable ceramic conductive paste (step (ii)) and prior to firing (step (iv)), a drying step (iii) is preferably performed. This step allows solvents to be evaporated from the paste. For example, the paste can be pre-dried at room temperature for a few minutes and then dried at a temperature of 80 to 150 °C for 5 to 15 minutes, whereby the exact temperatures and times depend particularly on the paste used. The drying step has the advantage of preventing spontaneous evaporation of the solvents at high firing temperatures, which could lead to blisters or cracks.

[0087] In step (iv), the ceramic conductive paste is baked, whereby the paste particles, in particular the glass frit particles, for example, fuse at least partially with the surface of the thin glass sensor plate. Subsequent cooling of the substrate solidifies the ceramic component, e.g., the glass frit, in the paste, thus forming a strong mechanical bond to the substrate. This enables the good adhesion properties of the conductive structures to the sensor plate.

[0088] The baking temperature is preferably between 500 - 700 °C, particularly preferably between 500 - 540 °C when using low-melting pastes or between 650 - 680 °C when using high-melting pastes.

[0089] The firing of the fireable ceramic conductive paste can be carried out under very different conditions. The conditions selected in the process will generally depend on the ceramic conductive paste and the desired planarity of the front plate and, in particular, the sensor plate during firing. For example, low-melting silver pastes with a melting range of 500 to 540 °C or IR-absorbing conductive pastes are advantageously used. At a preferred firing temperature in the range of 500 to 700 °C, the planarity should be essentially maintained. According to the invention, it has proven particularly advantageous if a planarity of ≤ 0.05 mm can be maintained during firing in step (iv).

[0090] For this purpose, the firing is generally carried out using special horizontal holders for continuous furnaces or special vertical holders for batch furnaces.

[0091] In addition, burning-in parameters such as temperature, heating time, oscillation speed, air pressure during cooling, cooling time and / or the choice of a suitable heat source, such as heating coil, IR emitter, laser beam device with high energy density for selective burning, are generally matched to the conductive paste and the front or sensor plate.

[0092] In a preferred embodiment, a structured, essentially transparent, electrically conductive layer, in particular a semiconductor oxide layer, is additionally arranged on the front plate, but in particular on an optional sensor plate. This is preferably located as a more or less coherent coating, e.g. made of ITO, directly on the sensor plate. Therefore, in the method according to the invention, a structuring of the electrically conductive metal oxide layer is generally carried out in a step (i) before carrying out steps (ii) and (iv). The structuring is generally carried out via an etching step or a laser ablation step. In an etching step, a suitable etching paste is generally applied to the parts of the semiconductor oxide layer to be removed. This can advantageously be done by screen printing. Suitable etching pastes are, in particular, etching pastes containing phosphoric acid.HF and chloride-free etching pastes suitable for screen printing are particularly preferred.

[0093] Alternatively or in addition, structuring of the semiconductor oxide layer can be achieved by exposure to suitable laser radiation. In a so-called laser ablation step, the semiconductor oxide is removed from an irradiated area by the laser radiation. The structuring of ITO coatings with laser radiation depends primarily on the glass thickness, its coating, in particular the coating thickness, and the desired resolution.

[0094] In this way, the desired sensor structures are obtained. Furthermore, especially in the case of prefabricated glass panes coated over their entire surface with an electrically conductive layer, regions can be obtained that are free of the essentially transparent, electrically conductive layer and on which the conductive structure can be applied in step (ii).

[0095] In a further preferred embodiment, after carrying out steps (ii) and (iv) and optionally steps (i) and / or (iii), the following steps are carried out: (iv) soldering of the ceramic conductive structure at the locations intended for connection to a flex cable and / or the flex cable; and (v) Soldering to connect the flex cable to the ceramic conductive structure on the front and / or sensor plate.

[0096] The method of soldering is not restricted according to the invention, although precision is required, particularly with regard to the close spacing between the multiple wires of the flex cable. For example, soldering can be carried out by bar soldering, thermode soldering or reflow soldering, with reflow soldering being preferred. In reflow soldering (also "reflow soldering"), the solder paste or the ceramic conductive structure is only heated to the required soldering temperature. The solder is applied independently of this, before the electronic components are fitted. In step (iv), preferably only the ceramic conductive structure of the sensor plate is soldered at the intended contact points, i.e. at the solder pads. The soldering, i.e. the application of solder, can be carried out in a variety of ways, e.g. with solder paste, solder preforms, soldering in an immersion or wave bath or electrochemical coating.Solder paste is preferred, as it has the advantage that the tacky flux generally contained in the solder paste allows the flexible cable to be fixed to the conductive structure until soldering. This allows even the smallest contact surfaces to be precisely soldered.

[0097] The invention has numerous advantages. The control unit according to the invention, particularly when designed as a capacitive control unit, combines the possibility of broad applicability with simple and cost-effective production. This control unit can be used particularly advantageously underwater, where even in the presence of water or an aqueous liquid such as a chlorinated aqueous liquid or salt water, in particular seawater, contact and / or approaches, in particular of a person or possibly another living being, e.g. a fish, can be detected. The use of a particularly thin sensor plate enables very thin control units in the overall structure, which are also lightweight.At the same time, the use of a fired ceramic conductive paste to form the conductive structures ensures excellent adhesion of the conductive structures to the glass substrate, whether the front panel or a sensor plate, as well as high resistance to environmental influences, UV radiation, and chemical influences, for example, even to adhesives used in subsequent process steps. This facilitates further processing and enables a wide range of applications.

[0098] The invention is illustrated below with reference to three non-limiting embodiments of an operating unit according to the invention, which is particularly well suited for use under water, e.g. in a wall or floor of a swimming pool. Reference is made to the Fig. 1 to 3.

[0099] Fig. 1 shows a cross section through a capacitive operating unit according to the invention, in which a ceramic conductive structure and a structured, essentially transparent, electrically conductive layer are arranged on both sides of a sensor plate present here, wherein the conductive structures and electrically conductive layers arranged on both sides are contacted via a single flexible cable.

[0100] In the Fig. Figure 1 shows a cross-section through a capacitive control unit 1 comprising a 3 mm thick glass front panel 2. Evaluation electronics 4 are arranged on a first surface 3 of the front panel 2. The front panel 2 has a substantially transparent area 5 and a non-transparent area 6.

[0101] The capacitive operating unit 1 also comprises a sensor plate 7 with a thickness of 1.1 mm. The first surface 8 of the sensor plate 7 is arranged facing the first surface 3 of the front plate 2. The sensor plate 7 thus has a first surface 8 facing the front plate 2 and a second surface 9 facing away from the front plate 2. On both sides of the sensor plate 7, i.e. on both surfaces 8 and 9, a ceramic conductive structure 10 and 11 is arranged directly, which is formed from a fired ceramic silver paste, e.g. with a silver conductive paste suitable for screen printing with a silver content of 60% or 80%, and comprises conductor tracks and solder pads. In addition, on both sides of the sensor plate 7, i.e. on both surfaces 8 and 9, a structured, essentially transparent, electrically conductive layer 12 and 13 is arranged, which is designed here as an ITO layer.The first ITO layer 12 is structured to form lines in the X direction, and the second ITO layer 13 is structured to form lines in the Y direction, so that the sensor is formed from both ITO layers 12 and 13. In the edge region of the sensor plate 7 (not visible here), the respective X and Y lines of the ITO layers 12 and 13 are contacted by the conductor track structures made of ceramic silver conductive paste 10 and 11. The conductor track structures 10 and 11 are in turn combined to form a connection point for a flex cable 14 with corresponding solder pads (not visible here), which is also located in the edge region of the sensor plate 7 and is concealed from view by the non-transparent area 6 of the front plate 2.

[0102] The electrical connection between the evaluation electronics 4 arranged on the front panel 2 and the conductive structures 10 and 11 of the sensor plate 7 is realized by a flexible cable 14, which alternately contacts both the conductive structures 10 on the first surface 8 of the sensor plate 7 facing the front panel 2 and the conductive structures 11 on the second surface 8 of the sensor plate 7 facing away from the front panel 2. The connection of the flexible cable 14 to the conductive structures 10 and 11 is realized by a soldered connection using a solidified solder paste (not visible here).

[0103] In this embodiment, an adhesive layer 15 is located between the front plate 2 and the sensor plate 7. This adhesive layer 15 consists of an OC adhesive (optically clear adhesive) and is formed over the entire surface, ie without interruptions or cavities.

[0104] To carry out the manufacturing method according to the invention, in the first embodiment shown here, the thin glass plate serving as sensor plate 7, which is fully coated with ITO, is first structured by etching to create sensor lines in the X (layer 12) and Y directions (layer 13) as well as ITO-free areas, particularly in the edge region of the sensor plate 7. The etching step is carried out on each side 8 and 9 of the sensor plate 7 by printing etching paste, for example an HF- and chloride-free, screen-printable etching paste, with the corresponding X or Y lines through a screen using a screen printing technique. The etching paste is then thermally activated, for example for 15 minutes at 150°C, and subsequently washed. In the ITO-free areas thus created, the ceramic silver conductive paste is then applied to the first surface 8 and subsequently to the second surface 9 of the sensor plate 7 using screen printing.The paste is then dried first at room temperature for 5 minutes and then at 120 to 150 °C for 5 to 10 minutes. The silver conductive paste is then baked at a temperature between 500 and 700 °C.

[0105] The front panel 2 is then fitted with the evaluation electronics 4 using SMD soldering. The solder pads provided on the conductive structures 10 for connecting the flexible cable 14 are then coated with solder paste having a melting range of 230–245°C, the flexible cable 14 is fixed to them, and soldered using a reflow soldering process. The solder pads provided on the conductive structures 11 for connecting the flexible cable 14 are then coated with solder paste having a melting range of approximately 170°C, the flexible cable 14 is also fixed to them, and soldered using a reflow soldering process. Following this, an OC adhesive is applied over the entire surface of the front panel 2 and / or the sensor plate 7 in the designated area. The sensor plate 7 is then attached to the front panel 2 by simply pressing it in place. The prepared adhesive layer 15 adheres the sensor plate 7 to the front plate 2.

[0106] 22 means water or, more generally, an aqueous liquid and 23 a container wall, e.g. of a swimming pool or an aquarium, into which the operating device is integrated.

[0107] Fig. Figure 2 shows a cross section through a capacitive operating unit 1 according to a second embodiment of the invention, in which a ceramic conductive structure 10, 11 and a structured, essentially transparent, electrically conductive layer 12, 13 are arranged on both sides 8 and 9 of the sensor plate 7. In contrast to the first embodiment of Fig. 1, spacers 16, 17 are located between the front panel 2 and the sensor plate 7, which in the embodiment shown here are bonded to the front panel 2 using an epoxy adhesive. The spacers 16 and 17 form a gap 18 between the front panel 2 and the sensor plate 7. The front panel 2 is fitted with the spacers 16, 17 in the same operation as the front panel 2 is fitted with the evaluation electronics 4. Furthermore, in this embodiment, the conductive structures 10, 11 arranged on both sides 8 and 9 as well as the electrically conductive layers 12, 13 are connected to the evaluation electronics 4 via two spring contacts 20 and 21, which are designed here as metal clips, and an electrical conductive structure 19 on the front panel 2. Otherwise, the same reference numerals have the same meaning as in Fig. 1.

[0108] Fig. Figure 3 shows a third embodiment of a capacitive control unit according to the invention. (a) is a plan view of the control unit, (b) is a side view of the control unit, and (c) is an exploded view of the control unit.

[0109] In Fig. Figure 3 (a) shows a schematic plan view of a capacitive operating unit 1 of a third embodiment. On a glass front panel 2, an elongated slider 28 and a round sensor button 29 are shown as exemplary operating elements. In the side view of the Fig. 3 (b) it can be seen that these operating elements protrude to varying degrees from the plane of the front panel 2. The sensor button 29 protrudes further from the plane of the front panel 2 than the slider 28. A person in the water can therefore easily determine by feeling the surface of the operating unit 1 whether they have the slider 28 or the sensor button 29 in front of them. This means that a person in the water can operate the operating unit 1 safely and conveniently even if the operating unit may be difficult to see visually. The operating elements can in principle have very different surface structures, which can be ground or - as shown here - raised. In addition, the operating elements can also have different surface roughnesses to distinguish them.

[0110] Fig. 3 (c) shows an exploded view of the control unit 1. On the front panel 2 made of glass, the slider 28 and the sensor button 29 made of Fig. 3 (a) and (b) respectively. Towards the interior of the control unit 1, a design print 27, a glaze print 26, and a blocking print 25 are shown in the specified order. Behind this is a so-called conductor print 24, which contains conductor tracks and capacitive sensor electrodes. 4 represents the evaluation electronics, which is illustrated here using individual small components. List of reference symbols 1 Capacitive control unit for underwater use 2 Glass front panel 3 First surface of the front panel 4 Evaluation electronics 5 Essentially transparent area of ​​the front panel 6 Non-transparent area of ​​the front panel 7 Sensor plate made of thin glass 8 First surface of the sensor plate, facing the front panel 9 Second surface of the sensor plate, facing away from the front plate 10,11 ceramic conductive structures made of fired ceramic conductive paste 12,13 structured essentially transparent, electrically conductive layer 14 flex cables 15 adhesive layer 16,17 spacers 18 gap 19 electrical wiring structure on front panel 20, 21 spring contacts 22 Water; aqueous liquid 23 Tank wall into which the control unit is integrated 24 conductor tracks, sensor electrodes; conductor track printing 25 locking pressure 26 Glaze print 27 Design printing 28 sliders 29 Sensor button

Claims

[1] Operating unit (1) for use under water, with a front plate (2) made of glass and electrical sensor elements (24) for evaluating an electrical capacity, and a control unit, wherein a fired ceramic conductive paste is applied to the front plate (2) and / or an optionally present sensor plate (7), characterized bythat the control unit is configured to detect touches and approaches of a person to the operating unit (1) and to trigger an action in response thereto when the operating unit (1) is underwater, wherein the operating unit (1) is a capacitive operating unit, wherein the electrical sensor element (24) is formed by an electrically conductive coating, and wherein the operating unit (1) comprises at least two electrical sensor elements (24) which are designed as a sensor button and / or slider which are connected to a microcontroller, wherein the sensor button and / or slider react to a touch or approach by the person with a change in a capacitance, and the control unit is configured to infer a touch or approach by the person from the extent (sensor stroke) of the change in the capacitance as well as its temporal change in at least two sensor elements (24) and also to detect,whether the capacitive control unit (1) is in contact with water or outside of water. [2] Control unit (1) according to claim 1, characterized by that a structured, substantially transparent, electrically conductive layer (12, 13) is arranged on the front plate (2) and / or the sensor plate (7). [3] Control unit (1) according to claim 1 or 2, characterized by that the sensor elements (24) are placed on the front plate (2) and / or the sensor plate (7), wherein a ceramic conductive structure (10, 11) made of the fired ceramic conductive paste is arranged on the front plate (2) and / or the sensor plate (7) on which the sensor elements (24) are placed. [4] Control unit (1) according to one of claims 1 to 3, characterized by that the fired ceramic conductive paste contains at least 50 wt.% silver. [5] Control unit (1) according to one of claims 1 to 4, characterized bythat at least one sensor element (24) is arranged on the front plate (2). [6] Control unit (1) according to one of claims 1 to 5, characterized by that the front panel (2) is designed such that at least one of the locations at which a sensor element (24) is located on or behind the front panel (2) differs haptically from the surroundings of this location. [7] Control unit (1) according to one of claims 1 to 6, characterized by that it contains a sensor plate (7) and at least one ceramic conductive structure (10, 11) is arranged on both sides of the sensor plate (7). [8] Control unit (1) according to one of claims 1 to 7, characterized by that the front panel (2) has a thickness in the range of 1 mm to 10 mm. [9] Control unit (1) according to one of claims 1 to 8, characterized by that the sensor plate (7) made of glass has a thickness in the range of 0.2 to 2.0 mm. [10] Control unit (1) according to claim 9, characterized by that at least one spacer (16, 17) is arranged between the front plate (2) and the sensor plate (7) and the ceramic conductive structure (10, 11) of the sensor plate (7) is contacted via at least one spring contact (20, 21). [11] Control unit (1) according to one of claims 1 to 10, characterized by that a housing is arranged on a first surface (3) of the front panel (2) facing the interior of the operating unit (1), which first surface is at least partially coated with at least one opaque layer, the inner surface of which can at least partially reflect light rays; and at least one illuminant arranged in a space between the housing and the first surface (3) of the front panel (2), wherein light rays generated by the illuminant can at least partially penetrate the front panel (2). [12] A method for producing an operating unit (1) for underwater use, comprising a front plate (2) made of glass and electrical sensor elements (24) for evaluating an electrical capacitance, and a control unit, wherein a fired ceramic conductive paste is applied to the front plate (2) and / or an optionally present sensor plate (7), and wherein the control unit is configured to detect touches and approaches of a person and to trigger an action in response thereto when the operating unit (1) is underwater, wherein the operating unit (1) is a capacitive operating unit, wherein the electrical sensor element (24) is formed by an electrically conductive coating, and wherein the operating unit (1) comprises at least two sensor elements (24) designed as a sensor button and / or slider, which are connected to a microcontroller,wherein the sensor button and / or slider react to a touch or approach by the person with a change in capacitance and the control unit is designed to infer a touch or approach by the person from the extent (sensor stroke) of the change in capacitance and its temporal change in at least two sensor elements (24) and also to detect whether the capacitive operating unit (1) is in contact with water or outside of water, the method comprising the following steps: (ii) applying a burnable ceramic conductive paste to the front plate (2) and / or the sensor plate (7) and (iv) Firing the ceramic conductive paste. [13] Method according to claim 12, characterized by that the baking temperature in step (iv) is in the range of 500 to 700°C.

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