EP2748369B1 - Domestic appliance having a touch-sensitive operating and display device - Google Patents

Description

The invention relates to a household appliance with a touch-sensitive operating and display device which has a display unit for displaying operating information and a light-permeable carrier part. At least one capacitive sensor electrode is arranged on the carrier part as part of a touch capacitor, which is arranged in overlap with the display unit on the one hand and in overlap with a touch-sensitive actuation surface of the operating and display device on the other hand.

In the present case, the interest is directed in particular to an LED display with an associated capacitive operating device. In such displays, light elements - LEDs - are used, by means of which function signs or display symbols can be backlit. Such an operating and display device is, for example, from the document DE 102 36 718 A1 known. This operating and display device contains an operating panel, which is a one-piece plastic injection-molded component made from ABS plastic. The control panel has a circular fluoroscopic area in which the material thickness of the panel material is reduced compared to the standard material thickness in such a way that the fluoroscopic area is translucent. This transillumination area forms an optical display device - display symbols or function signs are attached to the surface of the transillumination area and can be illuminated by means of a light-emitting element, such as a light-emitting diode. The light element is attached to a circuit board. Furthermore, a sensor electrode is attached to the rear of the control panel, which is part of a capacitive switch or part of a touch capacitor. The sensor electrode is electrically connected to the circuit board and thus to an evaluation unit via a coupling element or contact part.

From the pamphlet DE 28 24 973 A1 an operating and display device for a household appliance is known. On a circuit board, which is connected to the other controls of the household appliance via a ribbon cable, is a two-line, with Display with fonts and symbols applied. The display is covered by a control panel or control panel, which is provided with transparent, metallic surfaces. These metallic surfaces together with the surfaces underneath form a capacitive switching element that controls the command. The display is equipped, for example, with light elements in LED or LCD technology.

It is therefore already state of the art to use transparent sensor electrodes which are arranged above a display unit (display) or in an overlap with the display unit, for example from DE 103 26 684 A1 or DE 10 2009 011 678 A1 . With such a touch-sensitive operating and display device, the user can touch a touch-sensitive operating surface for operating the household appliance, which is also arranged in an overlap with the sensor electrodes and the display unit. The sensor electrodes are therefore located between the actuation surface on the one hand and the display unit on the other hand, the display unit being perceptible to the user due to the transparency of the sensor electrodes and not being covered by the sensor electrodes. In the prior art, so-called ITO layers (indium tin oxide) are used, through which the sensor electrodes are formed. Such layers are predominantly transparent to visible light. However, the ITO layers find their limits when they are applied to three-dimensional surfaces. They are only suitable to a limited extent for this. In particular, when the carrier part on which the sensor electrodes are arranged has a curved - for example convex or concave - surface, as can be the case with control panels of household appliances, the ITO layers can no longer be used satisfactorily. In addition, raw materials are relatively expensive compared to other electrically conductive materials.

The document US 2005/209392 A1 discloses nanotubes in a matrix of adhesive for a touch-sensitive operating and display device.

The object of the invention is to create a household appliance with an operating and display device in which the at least one sensor electrode can also be attached to the carrier part with little technical effort and at low cost, in particular if the carrier part has a three-dimensional - for example a curved - surface having.

According to the invention, this object is achieved by a household appliance having the features according to patent claim 1. Advantageous embodiments of the invention are the subject matter of the dependent claims, the description and the figures.

A household appliance according to the invention comprises a touch-sensitive operating and display device which has a display unit which is designed to display operating information. The operating and display device also has a translucent or transparent carrier part on which at least one capacitive, electrically conductive sensor electrode is arranged as part of a touch capacitor. The sensor electrode is arranged in an overlap with the display unit on the one hand and in an overlap with a touch-sensitive actuation surface of the operating and display device on the other hand. The operating surface can be touched or tapped by the user in order to operate the household appliance. According to the invention it is provided that the at least one sensor electrode is formed from a - at least for visible light - transparent and electrically conductive lacquer and / or adhesive which contains nanotubes made of carbon.

The effect according to the invention is thus achieved through the use of a special material for the sensor electrode, namely through the use of a translucent and electrically conductive adhesive and / or lacquer. It has been found that such materials are significantly better suited for application to three-dimensional surfaces than, for example, the so-called ITO layers, which consist of indium tin oxide. The household appliance according to the invention thus has the advantage that the at least one sensor electrode can be attached to the carrier part without much effort even if the same carrier part has three-dimensional, for example curved, surfaces. While the layers formed from indium tin oxide are only suitable to a limited extent for application to such surfaces, transparent and conductive lacquers and / or adhesives can also be applied to concave or convex surfaces without much effort. The operating and display device of the household appliance according to the invention can thus be shaped or configured as desired - it can have a wide variety of geometric shapes without its functionality having to be restricted due to the material of the sensor electrode. Compared to raw materials, transparent and electrically conductive paints or adhesives, which contain CNT are also relatively inexpensive, so that overall costs can be saved.

In the present case, a household appliance is understood to mean a device which is used for housekeeping. The household appliance is therefore a device which is designed for the treatment of household objects, for example items of laundry, dishes, food and the like. It can be a large household appliance, such as a washing machine, a tumble dryer, a dishwasher, a cooking appliance, an extractor hood, a refrigerator, a fridge-freezer or an air conditioner. However, it can also be a small household appliance, such as a fully automatic coffee machine or a food processor.

It proves to be particularly advantageous if the at least one sensor electrode is attached to the carrier part by screen printing. The at least one sensor electrode can therefore be applied to the carrier part in a screen printing process. In this way it is possible to apply differently designed or shaped sensor electrodes particularly effectively and without much effort to the carrier part. This is particularly advantageous when a large number of electrodes are used, which are arranged at a relatively small distance from one another. On the one hand, the screen printing process ensures extremely precise positioning of the sensor electrodes; on the other hand, it also prevents an unwanted short circuit between the sensor electrodes - for example due to inaccurate positioning.

According to the invention, the operating and display device has a plate-like, transparent and electrically non-conductive pane, the front side of which forms the touch-sensitive actuation surface that can be touched or tapped by the user to operate the household appliance. The pane thus represents a display window made of a translucent material. The pane can be inserted into a through opening of a control panel of the household appliance; it can be welded into the control panel, for example. The use of such a disk, which is arranged in an overlap with the at least one sensor electrode and in an overlap with the display unit and whose front side forms the touch-sensitive actuation surface, has the advantage that, on the one hand, the The display unit can be protected from external influences and, on the other hand, the outer surface of the operating and display device can also be designed in a visually appealing manner in a wide variety of ways, regardless of the display unit. For example, different device variants with different panes - for example with different colors - can be provided without the display unit having to be redesigned.

With regard to the choice of material, it has proven to be advantageous if the pane is made of transparent plastic. Such a material can namely be shaped in the most varied of ways, so that a three-dimensional configuration of the actuating surface is also made possible.

The pane can also be made from a material that is tinted, in particular in color. A (color) tinted design of the pane is based on the knowledge that the transparent and electrically conductive paints and / or adhesives used do not necessarily have 100% transparency, but the transparency can be between 80% and 100%. If a completely translucent pane were used, the user might also perceive the sensor electrode optically. To avoid this, the transparency of the pane can be adapted to the transparency of the conductive paints and / or adhesives. The design of the pane from a color-tinted material also ensures that any blocking pressure applied to the rear of the pane cannot be seen on the operating side or on the side of the actuating surface.

The carrier part on which the at least one sensor electrode is arranged can be formed by the pane itself. The at least one sensor electrode is arranged on a rear side of the pane - opposite the front side. The arrangement of the sensor electrode on the pane has the advantage that the use of a separate support part is unnecessary, and the pane takes on two different functions, namely on the one hand the function of covering the operating and display device and on the other hand also the function of carrying the at least one Sensor electrode. Components can thus be saved. The pane can be arranged resting on the display unit in such a way that the at least one sensor electrode rests on the rear side of the pane on the one hand and on a front side of the display unit facing the pane on the other hand. The at least one sensor electrode thus bridges the distance between the display unit on the one hand and the pane on the other hand or fills this distance. This has the advantage that no air gaps are formed between the actuation surface on the one hand and the sensor electrodes on the other, which could worsen the sensitivity of the capacitive operating and display device.

According to an alternative embodiment, it can be provided that the carrier part is designed as a transparent and flexible film, so that the at least one sensor electrode is arranged on the film. The film can be arranged on the display unit in such a way that the film rests on the one hand against a rear side of the pane and on the other hand against the display unit. The at least one sensor electrode can be arranged here either on a rear side of the film facing the display unit or on a front side of the film facing the pane. The film can be made of plastic. It can be a single or multi-layer film. It can be glued to the pane or back-injected directly using injection molding or injection compression molding processes (IML, IMD technology). With the printed, transparent film, there is no direct printing on the pane. This embodiment also has the advantage that the pane itself does not have to be geometrically adapted due to a screen printing on the back. This enables an even more flexible design of the operating and display device.

The display unit is preferably an LED display: it can have a light guide part or a light shaft which is designed to guide light and on which at least one function symbol is arranged as operating information in an overlap with the sensor electrode. The display unit can also have a lighting device - in particular with at least one light-emitting diode - which is used for backlighting or for optically highlighting the function sign when the user touches the touch-sensitive actuation surface in an overlapping area with the function sign. In this embodiment, the operating and display device thus represents a touch-sensitive LED display in which a function of the household appliance is selected by tapping the function symbol and the selection or the tapping of the function symbol is signaled by backlighting this symbol. The operating and display device is thus operated by touching the operating surface, specifically in an area of overlap with the sensor electrode and the function symbol. No mechanical movement of an operating button has to be carried out. This means in particular that control panels in which such control devices are used can be designed with a closed surface without an opening, which has the particular advantage in household appliances that no contamination can enter the interior of the device and the closed surface can also be cleaned particularly easily .

A thin film with the at least one function symbol can be attached to the light guide part. This can be a writing film or a light mask. The at least one functional symbol can thus be designed in the most varied of ways, regardless of the design of the light guide part. For different country variants or device variants, only different writing foils need to be used in each case, while the other components - in particular the light guide part itself - can be retained.

A plurality of capacitive sensor electrodes can also be arranged on the translucent or transparent carrier part in an overlap with the display unit and in an overlap with the touch-sensitive actuation surface, which are arranged at a distance from one another. By touching the actuation surface in an overlapping area with one of the sensor electrodes, a value of a parameter of the household appliance assigned to this sensor electrode can be selected. As a result, the most varied values of the parameter can be selected or a large number of parameters of the household appliance can be set with the aid of the touch-sensitive actuation surface.

In particular, each of the sensor electrodes is assigned at least one illuminable function symbol which is arranged on the light guide part in an overlap with the associated sensor electrode and which symbolizes the value of the parameter associated with the associated sensor electrode. The selection of a parameter value can thus be signaled with a function symbol. the A parameter value is thus selected by tapping one of the function symbols or the actuation area in an overlap area with one of the function symbols.

A wide variety of functional signs can therefore be attached to the light guide part, which can be backlit by means of the lighting device, namely through the light guide part. The function symbols each symbolize a different value of a parameter of the household appliance. In addition to a number or a digit - for example a temperature value or speed value - a value of the parameter can also be understood in the present case to mean designations or letter sequences, namely, for example, various operating programs of the household appliance and / or various additional functions. A parameter can, for example, also be an operating program for the household appliance - the name of the specific operating program is understood here as the parameter value. An additional function of the household appliance can also be set as a parameter, for example "easy-iron" or "prewash" in the case of a washing machine. The function symbols can generally include word symbols and / or numbers and / or symbols or symbols and / or combination symbols, such as word-symbol symbols.

The operating and display device can therefore be designed to set at least one of the following parameters of an operating process of the household appliance:
It can be designed as a parameter for setting an operating temperature. The display unit can have a large number of illuminated function symbols, each of which symbolizes a selectable value of the operating temperature. This embodiment proves to be particularly advantageous in a household appliance for caring for items of laundry - such as a washing machine or a tumble dryer - or in a dishwasher or in a household appliance for preparing food - such as an oven and / or a hob. The operator can tap the desired temperature value on the touch-sensitive actuation surface in order to set this temperature value.

In addition or as an alternative, the operating and display device can be designed to set a speed of movement of a component of the household appliance - for example a speed of rotation of a laundry drum. Here, the display unit can have a large number of illuminated function symbols, each of which symbolizes a selectable value of the speed of movement. This embodiment is particularly useful for household appliances that have a movable component, such as a laundry drum or the like.

In addition or as an alternative, the operating and display device can also be designed as a parameter to define an operating program. In this embodiment, the display unit can have a large number of illuminated function symbols, each of which symbolizes a different operating program. This applies accordingly to additional functions of the household appliance. Thus, each of the function symbols can identify a different additional function of the household appliance.

Further features of the invention emerge from the claims, the figures and the description of the figures. All of the features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination, but also in other combinations or on their own.

The invention will now be explained in more detail on the basis of individual preferred exemplary embodiments, as well as with reference to the accompanying drawings.

Fig. 1

in schematischer Darstellung eine Bedien- und Anzeigeeinrichtung eines Haushaltsgeräts gemäß einer ersten Ausführungsform der Erfindung; und

Fig. 2

in schematischer Darstellung eine Bedien- und Anzeigeeinrichtung eines Haushaltsgeräts gemäß einer zweiten Ausführungsform der Erfindung.

Show it:

Fig. 1

a schematic representation of an operating and display device of a household appliance according to a first embodiment of the invention; and

Fig. 2

a schematic representation of an operating and display device of a household appliance according to a second embodiment of the invention.

In Fig. 1 a control and display device 1 of a household appliance not shown in detail in the figures - namely in the exemplary embodiment of a washing machine - is shown in a schematic representation. The operating and display device 1 is a touch-sensitive LED display which has a large number of function symbols that can be backlit. The operating and display device 1 contains the following components: a light guide part 2 with function symbols attached to it, a disk 3 and a thin, flexible film 4.

The light guide part 2 represents a light shaft which is designed to guide light. A writing film 5, which can be a light mask, for example, is arranged on a front side of the light guide part 2. The writing film 5 has a large number of function characters, namely three columns of function characters in the exemplary embodiment, namely a first column of function characters 6, a second column of function characters 7 and a third column of function characters 8. The first column of function characters 6 symbolize each has a different value for an operating temperature of the washing machine. The function symbols 6 thus represent parameter values for the "operating temperature" parameter. The second column of function symbols 7 each symbolize a different value for a speed of the laundry drum for a spin mode of the washing machine. The function symbols 7 thus represent parameter values for the parameter “speed”. The third column of function symbols 8 contains a large number of different designations for additional functions of the washing machine. These are: "Quick", "Easy Iron", "Water plus", "Rinse plus", "Intensive" and "Prewash".

The function symbols 6, 7, 8 can be individually backlit independently of one another, namely with the aid of a lighting device (not shown). This lighting device can contain a plurality of light-emitting diodes which are arranged on a rear side of the light guide part 2, for example on a circuit board. A light-emitting diode can be assigned to each function symbol 6, 7, 8.

The disk 3 is a transparent or translucent disk, which can be made of transparent plastic, for example. It can be tinted in color. The disk 3 is a plate-like, flat and inherently rigid element. A front side 9 of the pane 3 simultaneously forms a touch-sensitive actuation surface 10, which can be touched by the user to select a parameter value. By touching the actuation surface 10, the user can set the parameters of the washing machine mentioned above or select the parameter values mentioned. This is done by simply tapping the function symbols 6, 7, 8.

The light guide part 2 with the function symbols 6, 7, 8 attached to it and possibly with other components, such as the lighting device mentioned, form a total of a display unit 11 which is used to display operating information, namely to display the respectively selected parameter values.

A large number of capacitive sensor electrodes 13, 14, each as part of a contact capacitor, which are formed from an electrically conductive and transparent material, are attached to a rear side 12 opposite the front side 9 of the pane 3. In the embodiment according to Fig. 1 three columns of sensor electrodes 13, 14 can also be provided, with FIG Fig. 1 for the sake of clarity, only two columns of sensor electrodes 13, 14 are shown. For example, each function symbol 6, 7, 8 is assigned a separate sensor electrode 13, 14, which is arranged in an overlap with the associated function symbol 6, 7, 8.

In the assembled state of the operating and display device 1, the rear side 12 of the pane 3 rests against the front side of the light guide part 2 or against the writing film 5. The sensor electrodes 13, 14 are then arranged in an overlap with the respective function symbols 6, 7, 8, so that by touching the actuating surface 10 in an overlapping area with one of the sensor electrodes 13, 14 or with one of the function symbols 6, 7, 8 of this function symbol 6, 7, 8 assigned parameter value can be selected, which is indicated by the backlighting of this function symbol 6, 7, 8.

On the right-hand side of the light guide part 2 there are also further symbols 15 which symbolize different phases of a washing process. These symbols 15 can be backlit by means of individual LEDs.

Below the symbols 15 there is a display area 16 with four seven-segment displays, which are used to display a period of time until the completion of a washing process. The remaining time of the washing process is thus displayed by means of the display area 16.

The individual sensor electrodes 13, 14 are electrically coupled to an evaluation unit or control device not shown in the figures, namely via respective conductor tracks 17. The conductor tracks 17 are also attached to the rear side 12 of the pane 3 and connect the respective sensor electrodes 13, 14 to the Evaluation unit. The conductor tracks 17 lead from the respective sensor electrode 13, 14 to the edge of the pane 3 and end at the edge of the pane 3. In order to then electrically connect these conductor tracks 17 to the evaluation unit, contact surfaces 18 are attached in the edge areas of the film 4. The film 4 is a centrally recessed, flexible plastic film. This means that it has a continuous recess 19. The contact surfaces 18 are attached to a front side 20 of the film 4 facing the pane 3 and can in principle be formed from any electrically conductive material. In particular, carbon and / or transparent and conductive lacquer and / or transparent and conductive adhesive is used here. The contact surfaces 18 are contacted with the evaluation unit via spring elements made of conductive material, which are located in plastic holders (so-called retainers).

Each sensor electrode is in itself part of a touch capacitor, the second capacitor plate of which is formed by the operator's finger. The sensor electrodes 13, 14 are namely arranged at a distance from the actuating surface 10 which is defined by the thickness of the disk 3. The operator can touch the actuation surface 10 in order to set the desired parameter value. Then the capacitance of the contact capacitor changes, which consists on the one hand of the operator's finger and on the other hand of the opposite sensor electrode 13, 14, as well as the dielectric in between (disk 3). This change in capacitance is then recorded and evaluated by the evaluation unit. Such a method is already in the document, for example DE 10 2005 041 113 A1 described.

The pane 3 made of transparent plastic is welded into a control panel of the washing machine. The application of the sensor electrodes 13, 14 to the pane 3 has its limits in the prior art if the pane 3 or its rear side 12 is designed three-dimensionally or if the pane 3 is concave or convex. In the prior art, a trade-off must be made here between the flexibility and configuration of the operating and display device 1 on the one hand and the technical possibility of applying the sensor electrodes 13, 14 on the other hand. In the prior art, so-called ITO layers (indium tin oxide) are used. This material cannot be applied to any surface, so that a new solution had to be found in order to be able to apply the sensor electrodes 13, 14 to panes 3 of any configuration.

The invention now goes the way of designing the sensor electrodes 13, 14 from a transparent and electrically conductive lacquer and / or a transparent and conductive adhesive. It has been found that such materials can be applied particularly easily to three-dimensional surfaces - for example to curved or arched panes 3 - without having to accept a restriction with regard to the shape of the operating and display device 1. On the one hand, the operating and display device 1 or the pane 3 can thus be shaped or configured as desired; on the other hand, an effective and reliable application of the sensor electrodes 13, 14 to the pane 3 is also made possible.

Furthermore, the selected materials for the sensor electrodes contain carbon nanotubes, the so-called "carbon nano tubes" (CNT). Such materials are transparent and conductive depending on the distribution and / or crosslinking of the nanoscale particles in the material. In this context, nanotubes are understood to be elongated carbon structures which, transversely to their longitudinal direction, have a size in the range of a few nanometers, in particular 1 to 2 nm.

Compared to raw materials, which are relatively expensive, conductive and transparent paints and adhesives that contain CNT are a significantly better and cheaper alternative.

Like the sensor electrodes 13, 14, the conductor tracks 17 can also be formed from electrically conductive and transparent lacquer and / or adhesive. Both the sensor electrodes 13, 14 and the conductor tracks 17 - that is to say the entire layout - are applied to the rear side 12 of the pane 3 in what is known as the screen printing process. This method makes it possible to apply any layout to the pane 3 with little technical effort. This method also prevents the sensor electrodes 13, 14 from touching one another and thus prevents a short circuit between the sensor electrodes 13, 14.

In Fig. 2 an operating and display device 1 'of a washing machine according to a second embodiment of the invention is shown. The operating and display device 1 'according to Fig. 2 essentially corresponds to that according to Fig. 1 so that only the differences between them are explained in more detail below:
In the embodiment according to Fig. 2 the sensor electrodes 13 ', 14', the conductor tracks 17 'and the contact surfaces 18' are attached to the flexible film 4 'made of plastic, which is now a film free of cutouts. It thus has in the exemplary embodiment according to Fig. 2 no continuous recess like the film 4 according to Fig. 1 on. The layout including the sensor electrodes 13 ', 14' and the conductor tracks 17 'as well as the contact surfaces 18' is preferably attached to a rear side of the film 4 'which faces the light guide part 2'. Thus, the contact surfaces 18 'can be electrically coupled to the evaluation unit without much effort.

The disk 3 'is therefore free of electrically conductive elements.

As in the embodiment according to Fig. 1 are also in the exemplary embodiment according to Fig. 2 the sensor electrodes 13 ', 14' and the conductor tracks 17 'and optionally the contact surfaces 18' are formed from an electrically conductive and transparent lacquer and / or adhesive. An advantage of the operating and display device according to Fig. 2 compared to according to Fig. 1 consists in the fact that the pane 3 'itself does not have to be geometrically adapted due to the screen printing on the rear side 12'. There is thus even greater flexibility in the geometric configuration and shape of the pane 3 'and of the entire operating and display device 1'.

List of reference symbols

1, 1 '

Control and display device

2, 2 '

Light guide part

3, 3 '

disc

4, 4 '

foil

5, 5 '

Writing foil

6, 6 '

first column of function characters

7, 7 '

second column of function characters

8, 8 '

third column of function characters

9, 9 '

Front

10, 10 '

touch-sensitive actuation surface

11, 11 '

Display unit

12, 12 '

back

13, 13 ', 14, 14'

Sensor electrodes

15, 15 '

Symbols

16, 16 '

Display area

17, 17 '

Conductor tracks

18, 18 '

Contact surfaces

19th

Recess

20, 20 '

Front

Claims (13)

1. Household appliance having a touch-sensitive operating and display device (1, 1') that has a display unit (11, 11') for displaying operating information and a transparent carrier part (3, 4') on which is arranged at least one capacitive sensor electrode (13, 14, 13', 14'), this forming part of a touch-sensitive capacitor and being so arranged as to overlap both the display unit (11, 11') and a touch-sensitive actuating surface (10, 10') of the operating and display device (1, 1'), wherein the at least one sensor electrode (13, 14, 13', 14') is formed from a transparent and electrically conductive coating and/or adhesive, characterised in that the coating and/or the adhesive contains carbon nanotubes, wherein the operating and display device (1, 1') comprises a panel-like, transparent and electrically non-conductive pane (3, 3'), the front side (9, 9') of which forms the touch-sensitive actuating surface (10, 10'), and wherein the at least one sensor electrode (13, 14, 13', 14') is arranged on a rear side (12, 12') of the pane (3, 3').
2. Household appliance according to claim 1, characterised in that the at least one sensor electrode (13, 14, 13', 14') is applied to the carrier part (3, 4') using a screen printing method.
3. Household appliance according to claim 2, characterised in that the pane (3, 3') is made of transparent plastic.
4. Household appliance according to claim 3, characterised in that the pane (3, 3') is made of a tinted material and in particular a colour-tinted material.
5. Household appliance according to claim 1, characterised in that the pane (3, 3') is so arranged as to fit closely against the display unit (11, 11'), such that the at least one sensor electrode (13, 14, 13', 14') fits closely against the rear side (12, 12') of the pane (3, 3') on one side and against a front side of the display unit (11, 11') on the other side.
6. Household appliance according to one of claims 1, 3 or 4, characterised in that the carrier part (3, 4') is designed as a transparent and flexible film (4, 4') and the at least one sensor electrode (13, 14, 13', 14') is attached to the film (4, 4'), wherein the film (4, 4') is so arranged on the display unit (11, 11') that the film (4, 4') fits closely against a rear side (12, 12') of the pane (3, 3') on one side and against the display unit (11, 11') on the other side.
7. Household appliance according to one of the preceding claims, characterised in that the display unit (11, 11') comprises:

   - a light conducting part (2, 2') for the purpose of conducting light and on which at least one function indicator (6, 7, 8, 6', 7', 8'), as operating information, is so arranged as to overlap the sensor electrode (13, 14, 13', 14'), and

   - a lighting device which allows the function indicator (6, 7, 8, 6', 7', 8') to be illuminated from behind when an operator touches the touch-sensitive actuating surface (10, 10') in an area which overlaps the function indicator (6, 7, 8, 6', 7', 8').
8. Household appliance according to claim 7, characterised in that a film (5, 5') comprising the at least one function indicator (6, 7, 8, 6', 7', 8') is attached to the light conducting part (2, 2').
9. Household appliance according to one of the preceding claims, characterised in that a multiplicity of capacitive sensor electrodes (13, 14, 13', 14') are so arranged on the light-permeable carrier part (3, 4') as to overlap both the display unit (11, 11') and the touch-sensitive actuating surface (10, 10'), and are discretely arranged, such that by touching the actuating surface (10, 10') in an overlap area containing one of the sensor electrodes (13, 14, 13', 14'), a value which is assigned to this sensor electrode (13, 14, 13', 14') in respect of a parameter of the household appliance can be selected.
10. Household appliance according to claim 7 or 8 and 9, characterised in that at least one illuminable function indicator (6, 7, 8, 6', 7', 8') is assigned to the sensor electrodes (13, 14, 13', 14') in each case, which function indicator is so arranged on the light conducting part (2, 2') as to overlap the associated sensor electrode (13, 14, 13', 14') and symbolises the parameter value which is assigned to the associated sensor electrode (13, 14, 13', 14').
11. Household appliance according to claim 9 or 10, characterised in that the operating and display device (1, 1') is designed for setting an operating temperature as a parameter, and the display unit (11, 11') has a multiplicity of illuminable function indicators (6, 7, 8, 6', 7', 8'), each of which symbolises a selectable value of the operating temperature.
12. Household appliance according to one of claims 9 to 11, characterised in that the operating and display device (1, 1') is designed for setting a speed of motion of a component of the household appliance as a parameter, and the display unit (11, 11') has a multiplicity of illuminable function indicators (6, 7, 8, 6', 7', 8'), each of which symbolises a selectable value of the speed of motion.
13. Household appliance according to one of claims 9 to 12, characterised in that the operating and display device (1, 1') is designed for defining an operating program as a parameter, and the display unit (11, 11') has a multiplicity of illuminable function indicators (6, 7, 8, 6', 7', 8'), each of which symbolises a different operating program.

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