DE102011081332A1 - Household appliance with a touch-sensitive operating and display device - Google Patents

Abstract

The invention relates to a domestic appliance having a touch-sensitive operating and display device (1, 1 ') which has a display unit (11, 11') for displaying operating information and a transparent carrier part (3, 16) on which a capacitive sensor electrode (13 13 ') is arranged as part of a contact capacitor (18) which overlaps with the display unit (11, 11') and in overlap with a touch-sensitive actuating surface (10, 10 ') of the operating and display device (1, 1'). is arranged, wherein the sensor electrode (13, 13 ') is formed of a transparent and electrically conductive paint and / or adhesive. According to a second aspect of the invention, the sensor electrode (13, 13 ') extends over an at least predominant extent of the display unit (11, 11'), wherein the operating and display device (1, 1 ') voltage limiting means for applying an electrical voltage (V ) on the sensor electrode (13, 13 '), Abgriffsmittel for tapping each of an electrical current at at least two Abgriffsstellen (20 to 23) of the sensor electrode (13, 13'), as well as an evaluation device (24), which in dependence on the tapped currents determined a contact point at which an operator touches the actuating surface (10, 10 ').

Description

The invention relates to a household appliance having a touch-sensitive operating and display device which has a display unit (display) for displaying operating information and a translucent or transparent carrier part, on which a capacitive sensor electrode is arranged as part of a contact capacitor. The capacitive sensor electrode is arranged in overlap with the display unit on the one hand and in overlap with a touch-sensitive actuating surface or contact surface of the control and display device on the other hand. The sensor electrode may be formed of a transparent and electrically conductive material.

In the present case, the interest is directed in particular to an LED display with an associated capacitive operating device. In such displays lighting elements - LEDs - are used by means of which function symbols 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 includes a control panel, which is a one-piece plastic injection-molded component, which is made of ABS plastic. The control panel has a circular transillumination region, in which the material thickness of the diaphragm material is reduced compared to the standard material thickness in such a way that the transillumination region is translucent. This transillumination area forms an optical display device - on the surface of the transillumination area display symbols or function symbols are attached, which can be illuminated by means of a luminous element - such as a light emitting diode. The light-emitting element is mounted on a printed circuit board. Furthermore, a sensor electrode is attached to a rear side of the control panel, which is part of a capacitive switch or component of a contact capacitor. The sensor electrode is electrically connected via a coupling element or contact part to the printed circuit board and thus to an evaluation unit.

From the publication DE 28 24 973 A1 an operating and display device for a household appliance is known. On a circuit board, which is connected via a ribbon cable with the other controls of the household appliance, a two-line, provided with fonts and symbols display is placed. The display is covered by a control panel or control plate, which is provided with transparent, metallic surfaces. These metallic surfaces form with underlying surfaces a capacitive switching element, which causes the command control. 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 overlap with the display unit. In such a touch-sensitive operating and display device, the user can touch a touch-sensitive actuating surface for operating the household appliance, which is likewise arranged in overlap with the sensor electrodes and the display unit. The sensor electrodes are thus located between the actuating surface on the one hand and the display unit on the other hand, wherein the display unit can be perceived by the user due to the transparency of the sensor electrodes and is not visually obscured 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 the visible light. However, the ITO layers find their limits when applied to three-dimensional surfaces. For this they are only partially suitable. In particular, when the carrier part, on which the sensor electrodes are arranged, has a convex-approximately convex or concave-surface, as may 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 ITO layers are not suitable for use in capacitive control and display devices of household appliances if the sensor electrode is to be applied to three-dimensional surfaces. In the prior art, the provision of a flexible in their shape control and display device is thus not possible. The flexibility of the known control and display devices finds its limits due to the materials used. Another limitation on the shape of the touch-sensitive actuating surface is caused by the plurality of capacitive sensing electrodes used in the prior art. Namely, in the prior art, a plurality of such sensor electrodes are used, which are spaced from each other behind the actuating surface - between the display unit on the one hand and the actuating surface on the other hand - are arranged. The user can only touch the actuating surface in those areas which are in overlap with the sensor electrodes. This also restricts the flexibility of the operating and display device with regard to their design or shaping.

It is an object of the invention to provide a household appliance with a control and display device, in which a flexibility in terms of the execution or shaping of the actuating surface is made possible.

This object is achieved by a household appliance with the features according to claim 1 on the one hand and by a household appliance with the features according to claim 3 on the other hand. Advantageous embodiments of the invention are the subject of the dependent claims, the description and the figures.

A household appliance according to a first aspect of the invention comprises a touch-sensitive operating and display device which has a display unit (display) which is designed to display operating information. The operating and display device also has a translucent or transparent carrier part, on which a capacitive, electrically conductive sensor electrode is arranged as part of a contact capacitor (the second capacitor plate is formed by the user's finger). The sensor electrode is arranged in overlap with the display unit on the one hand and in overlap with a touch-sensitive actuating surface of the operating and display device on the other hand. Thus, the sensor electrode between the display unit on the one hand and the touch-sensitive actuating surface on the other hand is arranged. The actuating surface can be touched or tapped to operate the household appliance by the user. According to the invention, it is provided that the sensor electrode is formed from a transparent and electrically conductive lacquer and / or adhesive, at least for visible light.

In particular, the paint and / or the adhesive contain carbon nanotubes, the so-called "carbon nanotubes" (CNT).

The effect of the invention is thus achieved by the use of a special material for the sensor electrode, through the use of a transparent and electrically conductive adhesive and / or paint. It has been found that such materials are much 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 also be attached to the carrier part without much effort if the same carrier part has three-dimensional - approximately curved - surfaces. While the layers formed from indium-tin oxide are only of limited suitability for application to such surfaces, transparent and conductive coatings 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 arbitrarily shaped or configured - it can have a wide variety of geometric shapes, without their functionality must be limited due to the material of the sensor electrode. Compared to raw materials, transparent and electrically conductive lacquers or adhesives are also relatively inexpensive, so that overall costs can be saved.

The above object is further achieved by a household appliance according to a second aspect of the invention, which comprises a touch-sensitive operating and display device having a display unit for displaying operating information and a transparent carrier part, on which a capacitive sensor electrode as part of a contact capacitor is arranged, which is arranged in overlap with the display unit on the one hand and in overlap with a touch-sensitive actuating surface of the control and display device on the other. The sensor electrode is formed of a transparent and electrically conductive material. The - in particular single - sensor electrode extends over an at least predominantly, in particular entire, extension region of the display unit. The operating and display device comprises voltage generating means, which are designed to apply an electrical voltage to the sensor electrode. The operating and display device also has tap means, which are designed to pick up respectively one electrical current at at least two tap locations of the sensor electrode. An evaluation device determines, depending on the tapped currents, a point of contact at which an operator touches the actuating surface above the sensor electrode.

Also, the household appliance according to the second aspect of the invention has the advantage that a flexible or diverse design of the operating and display device is made possible with regard to their shaping. Namely, this shape is not limited by a plurality of sensor electrodes each used in the prior art for setting a parameter of the household appliance. The operating and display device of the household appliance according to the invention is not limited to individual, predefined contact surfaces or buttons. The continuously running sensor electrode, which extends over the at least predominant extent of the display unit, thus also allows a diverse design of the entire operating and display device. This also has the advantage that within an operating sequence - for example, when setting parameters of an operating process of the household appliance - Actuating surfaces of different sizes can be provided, which is particularly user-friendly. The operating and display device can thus adapt to the respective given operating options or to the respectively available operating options. The continuous design of the sensor electrode and the inventive possibility of detecting the actuating point also ensure that a control or operation of the household appliance by means of gestures or finger movements is made possible on the actuating surface. Thus, a variety of different functions of the home appliance can be triggered in a user friendly manner.

The household appliance according to the first aspect of the invention and the household appliance according to the second aspect of the invention can also be combined with each other. The embodiments described below are applicable to both the household appliance according to the first aspect and the household appliance according to the second aspect of the invention.

In the present case, a household appliance is understood to be a device which is used for household management. The household appliance is thus a device which is designed for the treatment of household objects, such as laundry, crockery, food and the like. It may 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. But it can also be a small household appliance, such as a coffee machine or a food processor.

The sensor electrode is applied to the support member by, for example, a spray method or pad printing method or a screen printing method or a free-form surface geometry method or other suitable painting method.

Preferably, the operating and display device has a plate-like, transparent and electrically non-conductive disc whose front side forms the touch-sensitive actuating surface, which can be touched or tapped by the user for operating the household appliance. The disk thus constitutes a display window formed of a transparent material. The disk can be inserted into a passage opening of a control panel of the household appliance; it can be welded into the control panel. The use of such a disk, which is arranged in overlap with the sensor electrode and in overlap with the display unit and the front side forms the touch-sensitive actuating surface, has the advantage that on the one hand, the display unit can be protected from external influences and on the other hand, the outer surface the control and display device can be visually appealing in various ways, regardless of the display unit. Thus, for example, different device variants, each with different panes - for example, with different colors - can be provided without the display unit having to be redesigned.

With regard to the selection of materials, it proves to be advantageous if the disc is made of transparent plastic. Namely, such a material can be formed in various ways, so that a three-dimensional configuration of the actuating surface is made possible.

The disc can also be formed from a - in particular colored - toned material. A (color) tinted design of the disc is based on the finding 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 one would now use a completely translucent disc, the user would under certain circumstances also perceive the sensor electrode optically. In order to avoid this, the transparency of the pane can be adapted to the transparency of the conductive lacquers and / or adhesives. The design of the disc of a color-toned material also ensures that an optionally attached to the back of this disc locking pressure on the operating side or on the side of the actuating surface is not visible.

The carrier part, on which the sensor electrode is arranged, may be formed by the disk itself. In this embodiment, the sensor electrode may be arranged on a rear side of the pane opposite the front side. The arrangement of the sensor electrode on the disc has the advantage that the use of a separate support member is unnecessary, and the disc quasi two different functions takes on, on the one hand the function of covering the control and display device and on the other hand, the function of supporting the sensor electrode. It can thus be saved components.

The disk may be disposed on the display unit in such a manner that the sensor electrode rests on the back side of the disk on the one hand and on a front side of the display unit facing the disk on the other hand. Thus, the at least one sensor electrode bridges the distance between the display unit on the one hand and the disc on the other hand or fills this distance. This has the advantage that no air gaps between the actuating surface on the one hand and the sensor electrode on the other hand are formed, which could fundamentally worsen the sensitivity of the capacitive control and display device.

According to an alternative embodiment it can be provided that the carrier part is formed as a transparent and flexible film, so that the sensor electrode is attached to the film. The film may be arranged on the display unit such that the film rests on the one hand on a rear side of the pane and on the other hand on the display unit. The sensor electrode can be arranged here either on a rear side of the film facing the display unit or else on a front side of the film facing the window. The film may be formed of plastic. It can be a single or multi-layered film. It can be glued to the pane or injected directly back using injection molding or injection molding processes (IML, IMD technology). The printed, transparent film eliminates the direct printing of the disc. This embodiment also has the advantage that the disc itself does not have to be geometrically adapted due to a screen printing on the back. This allows an even more flexible shaping of the operating and display device.

The tapping means can be designed such that in each case an electric current is tapped at four different tapping points of the sensor electrode. Then, the evaluation device, depending on the tapped currents determine the point of contact at which the operator touches the actuating surface. It proves to be particularly advantageous if the respective currents are tapped at all four corners of the rectangular sensor electrode. In this way, it is possible to determine the point of contact with particularly great accuracy. In fact, a total of two coordinates of the contact point can be determined from the currents tapped at four different tapping points, on the one hand in the longitudinal direction and on the other hand in the transverse direction of the actuating surface. The determination of the point of contact is thus not limited to a single direction, so that a variety of possible functions of the household appliance can be triggered by touching the actuating surface.

The tapping points of the sensor electrode can each be electrically coupled to a capacitor, so that the respective electrical current is detected as a charge displacement on the capacitor caused by contact with the actuating surface. Thus, the currents can be measured reliably and effectively; namely, the initially charged capacitors are at least partially discharged when touching the actuating surface, so that electric current flows through the capacitors. These electrical currents can be detected separately from each other and used to determine the point of contact. The flow of current through the capacitors is based on the fact that when touching the actuating surface, a contact capacitor is formed which on the one hand has the sensor electrode and on the other hand the finger of the operator, which carries the electrical potential of the earth (ground). By this contact capacitor then also flows electric current, so that a charge shift takes place in the capacitors at the Abgriffsstellen the sensor electrode.

In principle, arbitrary methods can be used as detection method for detecting and evaluating the currents or changing the respective capacitances of the capacitors, namely in particular the following methods: charge transfer or successive approximation or sigma-delta or mutual capacitance measurement.

The evaluation device can determine the point of contact as a function of a ratio of the tapped currents. This is particularly easy to implement, so that the point of contact can be determined with little technical effort.

The voltage supply means are preferably designed for applying in each case an electrical voltage to at least two different locations of the sensor electrode. Preferably, in each case an electrical voltage is applied to four different locations of the sensor electrode. It proves to be particularly advantageous if in each case an electrical voltage is applied to all four corners of the rectangular sensor electrode. This embodiment also ensures that the contact point can be determined with great accuracy both in the longitudinal direction and in the transverse direction of the sensor electrode or two coordinates of the contact point can be calculated. By applying the electrical voltages at all four corners of the sensor electrode, the capacitors connected to the corners are charged, so that a charge displacement when touching the actuating surface is made possible.

The electrical voltages can be direct voltages or alternating voltages - such as square-wave voltages.

If alternating voltages are applied to the sensor electrode, these alternating voltages can each have a different frequency. The electrical voltages on At least two locations of the sensor electrode are applied, thus differ in their frequencies with each other. This makes it possible to determine the point of contact in a very specific manner: The tapped currents can be filtered in this embodiment so that different signal components, each having different frequencies, are obtained and analyzed. The amplitudes of these different signal components can then be put into proportion, and depending on this ratio, the point of contact can be determined. In this way, a particularly precise determination of the contact point is ensured.

In principle, the display unit can be any display, such as a TFT display or an LCD display. In one embodiment, however, it is provided that the display unit is an LED display and has a light guide part or a light shaft, which is designed for guiding light, and at which at least one function symbol as operating information in overlap with the sensor electrode - behind the sensor electrode - is arranged. The display unit can also have a lighting device-in particular with at least one light-emitting diode-which serves for backlighting or for optical highlighting of the function symbol when the operator touches the touch-sensitive actuating surface in an overlapping region with the function symbol. In this embodiment, the operating and display device thus represents a touch-sensitive LED display, in which a function of the household appliance selected by tapping the function character and the selection or tapping the function character is signaled by backlighting of this sign. The operating of the operating and display device thus takes place by touching the actuating surface, in an overlapping region with the sensor electrode and the function symbol. There must be no mechanical movement of a control knob performed. This means in particular that control panels, in which such controls are used without breakthrough can be formed with a closed surface, which has the particular advantage of home appliances that no impurities can enter the device interior and also the closed surface can be cleaned very easily ,

A thin foil 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 function character can thus be configured in various ways, regardless of the configuration of the light guide part. For different country variants or device variants thus only need to be used in each case different writing films, while the other components - in particular the light guide part itself - can be maintained.

At the light guide part and a plurality of function signs in overlap with the common sensor electrode - namely behind the sensor electrode - may be arranged. By touching the actuating surface in an overlapping region with one of the function symbols, the same function symbol can be visually highlighted by means of the lighting device, namely in each case in relation to other function symbols. This may, for example, be such that by touching the actuating surface in an overlapping region with one of the function symbols, a value of a parameter of the household appliance assigned to this function symbol is selected. In this way, a wide variety of values of the parameter can be selected or even a multiplicity of parameters of the household appliance can be set by means of the touch-sensitive actuating surface and by means of the common, single sensor electrode.

Thus, the sensor electrode may be associated with a plurality of separately illuminable function symbols, which are arranged on the light guide part in overlap with the common sensor electrode - namely behind the sensor electrode - and which each symbolize a value of the parameter of the household appliance. The selection of a parameter value can thus be signaled in each case with a function symbol. The selection of a parameter value is effected by tapping one of the function characters or the actuating surface in an overlap region with this function symbol. Which of the function signs was tapped is determined by means of the evaluation device on the basis of the tapped currents - as stated above. For this purpose, the point of contact is determined at which the operator touches the actuating surface.

Accordingly, a wide variety of functional signs can 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 number - such as temperature value or speed value - under a value of the parameter present terms or letter sequences are understood, namely, for example, different operating programs of the household appliance and / or various additional functions. A parameter may, for example, also be an operating program of the household appliance - the parameter value here being the name of the specific operating program Understood. Likewise, an additional function of the household appliance can be set as a parameter, in a washing machine about "easy to iron" or "prewash". The function characters may generally include word characters and / or numbers and / or icons, and / or combination symbols, such as word-image characters.

The operating and display device can be designed to set at least one of the following parameters of an operating process of the household appliance:

It can be designed to set an operating temperature as a parameter. The display unit can have a multiplicity of illuminable function symbols which each symbolize a selectable value of the operating temperature. This embodiment proves particularly in a household appliance for the care of laundry - such as a washing machine or a tumble dryer - or in a dishwasher or in a household appliance for food preparation - such as an oven and / or a hob - particularly advantageous. The operator can tap the desired temperature value on the touch-sensitive actuating surface to set this temperature value.

Additionally or alternatively, the operating and display device for adjusting a movement speed of a component of the household appliance - such as a speed of a laundry drum - be formed. Here, the display unit may have a multiplicity of illuminable function symbols which each symbolize a selectable value of the movement speed. This embodiment is particularly useful in such home appliances that have a movable component, such as a laundry drum or the like.

Additionally or alternatively, the operating and display device can also be designed to define an operating program as a parameter. In this embodiment, the display unit may have a plurality of illuminable function symbols, each symbolizing a different operating program. This applies accordingly for additional functions of the household appliance. Thus, each of the function characters can each identify a different additional function of the household appliance.

Further features of the invention will become apparent from the claims, the figures and the description of the figures. All the features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively indicated combination but also in other combinations or alone.

The invention will now be described with reference to individual preferred embodiments, as well as with reference to the accompanying drawings.

Show it:

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

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

3 a schematic schematic representation, based on which the manner of determining a point of contact is explained in detail.

In 1 is a schematic representation of an operating and display device 1 a household appliance not shown in the figures - namely in the embodiment of a washing machine - shown. The operating and display device 1 illustrates a touch-sensitive LED display having a plurality of function signs that can be backlit. The operating and display device 1 includes the following components: a fiber optic part 2 with attached function symbols, as well as a disc 3 ,

The light guide part 2 represents a light well, which is designed to conduct light. At a front 4 of the optical fiber part 2 which of the disc 3 is facing, is a writing film 5 arranged, which is for example a light mask. The writing foil 5 has a plurality of function characters, in the exemplary embodiment three columns of function characters, namely a first column of function characters 6 , a second column of function characters 7 , as well as a third column of function characters 8th , The first column of function characters 6 each symbolize a different value for an operating temperature of the washing machine. The function characters 6 thus represent parameter values for the parameter "operating temperature". The second column of function characters 7 each symbolize a different value for a speed of the laundry drum for a spin operation of the washing machine. The function characters 7 thus represent parameter values for the parameter "Speed". The third column of function characters 8th includes a variety of different names for additional functions of the washing machine. These are: "Fast", "Easy Iron", "Water Plus", "Rinse Plus", "Intensive" and "Prewash".

The function characters 6 . 7 . 8th can independently be backlit individually, namely by means of a lighting device (not shown). This lighting device may include a plurality of light-emitting diodes, which on a rear side of the optical fiber part 2 are arranged, such as on a circuit board. Each function character 6 . 7 . 8th can be assigned in each case a light emitting diode.

The disc 3 is a transparent or translucent disc, which may be formed for example of transparent plastic. It can be colored toned. The disc 3 is a plate-like, flat and intrinsically rigid element. A front 9 the disc 3 simultaneously forms a touch-sensitive actuating surface 10 which can be touched by the user to select a parameter value. By touching the actuating surface 10 The user can set the above-mentioned parameters of the washing machine or select the mentioned parameter values. This is done by simply tapping the function symbols 6 . 7 . 8th ,

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

At one of the front 9 the disc 3 opposite back 12 is a single, the entire back 12 the disc 3 covering, electrically conductive and transparent sensor electrode 13 attached as part of a touch capacitor. In the exemplary embodiment, the sensor electrode thus extends 13 over the entire surface of the back 12 and thus also over the entire extent of the display unit 11 , The sensor electrode 13 lies in the assembled state on the one hand on the back of the disc 3 and then on the front 4 of the optical fiber part 2 at. The sensor electrode 13 thus bridges the distance between the disc 3 on the one hand and the light guide part 2 on the other hand.

The sensor electrode 13 is thus in overlap with the function characters 6 . 7 . 8th arranged. In other words, the sensor electrode is located 13 over the function character 6 . 7 . 8th , so by touching the actuating surface 10 in an overlap area with one of the function characters 6 . 7 . 8th the function character 6 . 7 . 8th assigned parameter value can be selected, for example, by backlighting this selected function character 6 . 7 . 8th is signaled. To detect the point of contact at which the operator the actuating surface 10 touched, one is in 1 Evaluation device not shown provided.

On the right side of the fiber optic part 2 are also more symbols 14 present, which symbolize different phases of a washing process. These symbols 14 can be backlit by means of individual LEDs.

Below the symbols 14 there is a display area 15 with four seven-segment ads that indicate a time period until completion of a washing process. By means of the display area 15 So the remaining time of the washing process is displayed.

The disc 3 made of transparent plastic is welded into a control panel of the washing machine. The application of the sensor electrode 13 on the disc 3 finds its limits in the prior art when the disc 3 or her back 12 is designed three-dimensionally or if the disc 3 is concave or convex. In the prior art must be a tradeoff between the flexibility and design of the control and display device 1 on the one hand and the technical possibility of applying the sensor electrode 13 on the other hand. Namely, so-called ITO layers (indium tin oxide) are used in the prior art. This material can not be applied to any surface, so a new solution had to be found around the sensor electrode 13 also on arbitrarily designed discs 3 to be able to raise.

In the exemplary embodiment, the sensor electrode 13 formed from a transparent and electrically conductive lacquer and / or a transparent and conductive adhesive. It has been found that such materials are particularly easy on three-dimensional surfaces - such as curved or curved discs 3 - Can be applied without any restriction with regard to the shape of the operating and display device 1 must be accepted. On the one hand, therefore, the operating and display device 1 or the disc 3 are arbitrarily shaped or configured; On the other hand, it is also an effective and reliable application of the sensor electrode 13 on the disc 3 allows.

Such materials - namely conductive and transparent lacquers - preferably contain nanotubes made of carbon, the so-called "carbon nanotubes" (CNT). Such materials are transparent and dependent on the distribution and / or crosslinking of the nanoscale particles in the material conductive. In this context, nanotubes are understood as meaning elongate carbon structures which have a size in the range of a few nanometers, in particular 1 to 2 nm, transversely to their longitudinal direction.

Compared to the raw materials, which are relatively expensive, conductive and transparent paints and adhesives, especially those with CNT, a much better and cheaper alternative.

Increasing the flexibility of the design of the operating and display device 1 is also achieved in that, unlike in the prior art - there are a variety of smaller, juxtaposed sensor electrodes used - a single, large sensor electrode 13 is used, which extends substantially over the entire surface of the display unit 11 extends. Unlike in the prior art is with such a sensor electrode 13 the danger no longer exists that a short circuit between two adjacent sensor electrodes - for example, due to a complicated shape of the disc 3 - arises. In the present case, simply the entire back 12 with an electrically conductive layer (sensor electrode 13 ) without the shaping of the disc 3 is limited due to a plurality of sensor electrodes.

In 2 is an operating and display device 1' a washing machine according to a second embodiment of the invention shown. The operating and display device 1' essentially corresponds to the operating and display device 1 according to 1 so that only the differences between them are explained in more detail below:

In the embodiment according to 2 is the sensor electrode 13 ' on a flexible and made of plastic film 16 attached, which may be a single or multi-layer film. The foil 16 is - like the disc 3 ' - Made of a transparent material. The sensor electrode 13 ' may, for example, over the entire surface of the film 16 extend. The sensor electrode 13 ' is preferably on a back side of the film 16 attached, which the light guide part 2 ' is facing. Thus, the sensor electrode 13 ' be electrically coupled with the aforementioned evaluation without much effort.

When assembled, the film is lying 16 on the one hand at the back 12 ' the disc 3 ' and then on the front 4 ' of the optical fiber part 2 ' at.

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

As in the embodiment according to 1 is also in the embodiment according to 2 the sensor electrode 13 ' formed of an electrically conductive and transparent lacquer and / or adhesive.

As already stated, the evaluation device can determine a point of contact at which the operator controls the actuating surface 10 . 10 ' is touched to select a parameter value from the mentioned parameter values. A schematic diagram for explaining the determination of the contact point is in 3 shown. Shown is the sensor electrode 13 . 13 ' which has some ohmic resistance, as indicated by resistance symbols 17 is indicated. Will the actuating surface 10 . 10 ' touched by the operator, then becomes a touch capacitor 18 formed, which on the one hand by the sensor electrode 13 . 13 ' and on the other hand by a finger 19 the operator is formed. The rectangular sensor electrode 13 . 13 ' has four corners 20 . 21 . 22 . 23 on. Every corner 20 to 23 is with an evaluation device 24 electrically coupled, which with ground 25 (Earth) is electrically connected. The operator also carries the electrical potential of the earth.

The evaluation device also includes voltage generating means and tap means 26 , which for applying an electrical voltage to the sensor electrode 13 . 13 ' and for picking up electrical currents at the sensor electrode 13 . 13 ' are formed. And that is on every corner 20 to 23 in each case an electrical voltage V with respect to the ground 25 created. These electrical voltages may be equal voltages or voltages, each with a different amplitude. The voltages V may be DC voltages or AC voltages. Every corner 20 to 23 is also each with a capacitor 27 . 28 . 29 . 30 connected. On the other hand, the capacitors 27 to 30 with the crowd 25 be connected.

Due to the ohmic resistance of the sensor electrode 13 . 13 ' If necessary, the use of additional resistors in series with the capacitors is unnecessary 27 to 30 ,

The evaluation device 24 thus captures the electrical currents at the corners 20 to 23 the sensor electrode 13 . 13 ' , Depending on these currents - for example, depending on a ratio of these currents - the evaluation device 24 determine the point of contact. When the actuating surface 10 . 10 ' is not touched flows over the sensor electrode 13 . 13 ' no electricity, and the capacitors 27 to 30 are charged. Will now the actuating surface 10 . 10 ' touched, then the contact capacitor 18 educated. There are currents flowing from the capacitors 27 to 30 towards the contact capacitor 18 and then on to the mass 25 . namely over the finger 19 , These currents or the charge transfer in the capacitors 27 to 30 are now from the evaluation 24 recorded, for example according to the so-called charge transfer technique. If these currents are detected, the evaluation device 24 - for example, using a table or a formula - determine the point of contact. This can be defined for example by two coordinates, in the longitudinal direction and in the transverse direction of the sensor electrode 13 . 13 ' ,

Become to the corners 20 to 23 AC voltages applied, it can also be provided that these voltages each have a different frequency. The detected currents then have different signal components, each with different frequencies. These currents can then be subjected to frequency filtering, so that the amplitude of each signal component or frequency component is determined. The contact point can then be determined as a function of a ratio of the amplitudes of different frequency components.

LIST OF REFERENCE NUMBERS

1, 1 '

 Operating and display device

2, 2 '

 Light guide part

3, 3 '

 disc

4, 4 '

 front

5, 5 '

 Scripture film

6, 7, 8, 6 ', 7', 8 '

 function characters

9, 9 '

 front

10, 10 '

 actuating surface

11, 11 '

 display unit

12, 12 '

 back

13, 13 '

 sensor electrode

14, 14 '

 symbols

15, 15 '

 display area

16

 foil

17

 resistance symbols

18

 contact condenser

19

 finger

20 to 23

 corners

24

 evaluation

25

 Dimensions

26

 Voltage generating means, tap means

27 to 30

 capacitors

V

 tensions

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 10236718 A1 [0002]
• DE 2824973 A1 [0003]

Claims (15)

Household appliance with a touch-sensitive operating and display device ( 1 . 1' ), which is a display unit ( 11 . 11 ' ) for displaying operating information and a transparent carrier part ( 3 . 16 ), on which a capacitive sensor electrode ( 13 . 13 ' ) as part of a touch capacitor ( 18 ) which overlaps with the display unit ( 11 . 11 ' ) and in overlap with a touch-sensitive actuating surface ( 10 . 10 ' ) of the operating and display device ( 1 . 1' ), characterized in that the sensor electrode ( 13 . 13 ' ) is formed of a transparent and electrically conductive lacquer and / or adhesive, which in particular includes nanotubes made of carbon. Domestic appliance according to claim 1, characterized in that the sensor electrode ( 13 . 13 ' ) over an at least predominant, in particular entire, extension range of the display unit ( 11 . 11 ' ) and the operating and display device ( 1 . 1' ) comprises: - voltage generating means ( 26 ) for applying an electrical voltage to the sensor electrode ( 13 . 13 ' ), - tap means ( 26 ) for tapping each of an electric current at at least two tapping points ( 20 to 23 ) of the sensor electrode ( 13 . 13 ' ) and - an evaluation device ( 24 ), which is designed to determine, depending on the tapped currents, a contact point at which an operator controls the actuating surface ( 10 . 10 ' ) above the sensor electrode ( 13 . 13 ' ) touched. Household appliance with a touch-sensitive operating and display device ( 1 . 1' ), which is a display unit ( 11 . 11 ' ) for displaying operating information and a transparent carrier part ( 3 . 16 ), on which a capacitive sensor electrode ( 13 . 13 ' ) as part of a touch capacitor ( 18 ) which overlaps with the display unit ( 11 . 11 ' ) and in overlap with a touch-sensitive actuating surface ( 10 . 10 ' ) of the operating and display device ( 1 . 1' ), wherein the sensor electrode ( 13 . 13 ' ) is formed of a transparent and electrically conductive material, characterized in that the sensor electrode ( 13 . 13 ' ) over an at least predominant, in particular entire, extension range of the display unit ( 11 . 11 ' ) and the operating and display device ( 1 . 1' ) comprises: - voltage generating means ( 26 ) for applying an electrical voltage to the sensor electrode ( 13 . 13 ' ), - tap means ( 26 ) for tapping each of an electric current at at least two tapping points ( 20 to 23 ) of the sensor electrode ( 13 . 13 ' ) and - an evaluation device ( 24 ), which is designed to determine, depending on the tapped currents, a contact point at which an operator controls the actuating surface ( 10 . 10 ' ) above the sensor electrode ( 13 . 13 ' ) touched. Domestic appliance according to claim 3, characterized in that the sensor electrode ( 13 . 13 ' ) is formed of a transparent and electrically conductive lacquer and / or adhesive, which in particular includes nanotubes made of carbon. Domestic appliance according to one of the preceding claims, characterized in that the operating and display device ( 1 . 1' ) a plate-like, transparent and electrically non-conductive disc ( 3 . 3 ' ) whose front side ( 9 . 9 ' ) the touch-sensitive actuating surface ( 10 . 10 ' ). Domestic appliance according to claim 5, characterized in that the carrier part ( 3 . 16 ) the disc ( 3 ), and the sensor electrode ( 13 . 13 ' ) on a back side ( 12 . 12 ' ) of the disc ( 3 . 3 ' ) is arranged, wherein the disc ( 3 . 3 ' ) with respect to the display unit ( 11 . 11 ' ) is arranged, that the sensor electrode ( 13 . 13 ' ) on the back ( 12 . 12 ' ) of the disc ( 3 . 3 ' ) on the one hand and on a front side ( 4 . 4 ' ) of the display unit ( 11 . 11 ' ) on the other hand. Domestic appliance according to claim 5, characterized in that the carrier part ( 3 . 16 ) as a transparent and flexible film ( 16 ) is formed and the sensor electrode ( 13 . 13 ' ) on the film ( 16 ), the film ( 16 ) on the display unit ( 11 . 11 ' ) is arranged such that the film ( 16 ) on a back side ( 12 . 12 ' ) of the disc ( 3 . 3 ' ) on the one hand and on the display unit ( 11 . 11 ' ) on the other hand. Domestic appliance according to one of claims 2 to 7, characterized in that the tap means ( 26 ) for picking up each of an electric current at four different tapping points ( 20 to 23 ) of the sensor electrode ( 13 . 13 ' ), especially at all corners ( 20 to 23 ) of the rectangular sensor electrode ( 13 . 13 ' ), and the evaluation device ( 24 ) is designed to determine the point of contact in dependence on the tapped currents. Domestic appliance according to one of claims 2 to 8, characterized in that the tapping points ( 20 to 23 ) of the sensor electrode ( 13 . 13 ' ) each with a capacitor ( 27 to 30 ) are electrically coupled and the respective electrical current as a charge transfer to the capacitor ( 27 to 30 ) due to touching the actuating surface ( 10 . 10 ' ) is detectable. Domestic appliance according to one of claims 2 to 9, characterized in that the evaluation device ( 24 ) is designed to determine the point of contact in dependence on a ratio of the tapped currents. Domestic appliance according to one of claims 2 to 10, characterized in that the voltage generating means ( 26 ) for applying in each case an electrical voltage (V) to at least two, in particular to four, different locations of the sensor electrode ( 13 . 13 ' ) are formed. Domestic appliance according to claim 11, characterized in that the electrical voltages (V) are DC voltages. Domestic appliance according to claim 11, characterized in that the electrical voltages AC voltages (V), in particular each having a different frequency, are. Domestic appliance according to one of the preceding claims, characterized in that the display unit ( 11 . 11 ' ) comprises: - a light guide part ( 2 . 2 ' ) for guiding light, on which at least one function symbol ( 6 . 7 . 8th . 6 ' . 7 ' . 8th' ) as operating information in overlap with the sensor electrode ( 13 . 13 ' ) is arranged, and - a lighting device for backlighting the function character ( 6 . 7 . 8th . 6 ' . 7 ' . 8th' ) when an operator activates the touch-sensitive actuating surface ( 10 . 10 ' ) in an overlapping area with the function symbol ( 6 . 7 . 8th . 6 ' . 7 ' . 8th' ) touched. Domestic appliance according to claim 14, characterized in that on the light guide part ( 2 . 2 ' ) a plurality of function signs ( 6 . 7 . 8th . 6 ' . 7 ' . 8th' ) in overlap with the common sensor electrode ( 13 . 13 ' ) are arranged and by touching the actuating surface ( 10 . 10 ' ) in an overlapping area with one of the function signs ( 6 . 7 . 8th . 6 ' . 7 ' . 8th' ) same function character ( 6 . 7 . 8th . 6 ' . 7 ' . 8th' ) is optically highlighted by means of the lighting device.

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