WO2008080493A1

WO2008080493A1 - Operating arrangement for a household appliance

Info

Publication number: WO2008080493A1
Application number: PCT/EP2007/010546
Authority: WO
Inventors: Michael Jasch; Ralf Ehrlich
Original assignee: Prettl Home Appliance Solutions Gmbh
Priority date: 2006-12-21
Filing date: 2007-12-05
Publication date: 2008-07-10
Also published as: DE102006062393A1; DE102006062393B4

Abstract

The invention proposes an operating arrangement (20) for operating an electric device (10), particularly a household appliance (10), having a panel (22) made of an electrically insulating material, which comprises an inside (I) and an operating side (B), and having a sensor arrangement (30) for detecting an object (36) on the operating side (B), wherein the sensor arrangement (30) has a printed circuit board (24) and a sensor element (32) that are electrically connected to each other on the inside (I) of the panel (32) by means of a contact arrangement (34), wherein the sensor element (32) is made of an electrically conductive material, and is connected to the panel (22). For this purpose, the sensor element (32) is configured as a plane element that extends across a length (L) that is at least twice as long as the thickness of a human finger (36).

Description

Operating arrangement for a household appliance

The present invention relates to an operating arrangement for operating an electrical device, in particular a household appliance, with a diaphragm made of an electrically insulating material which has an inner side and an operating side, and with a sensor arrangement for detecting an object on the operating side, wherein the sensor arrangement comprises a printed circuit board and a sensor element disposed on the inside of the diaphragm, which are electrically connected to each other by means of a contact arrangement, wherein the sensor element is made of an electrically conductive material and connected to the diaphragm. Such an operating arrangement is known, for example, from WO 2006/034993 A1. In this known operating arrangement, a spring element is arranged between a printed circuit board and the inside of an insulating plate (diaphragm). The spring element is designed as a helical compression spring and has at the end facing the diaphragm to a spirally wound portion which bears against the inside of the diaphragm. By this operating arrangement, a capacitive proximity and / or touch switch is realized.

Capacitive touch switches have long been known. For the realization of control surfaces of glass ceramic cooktops, it is known, for example, from DE 80 33 570 U1 to provide a large capacitor area on the upper surface and two smaller capacitor surfaces on the rear side of the glass ceramic plate. In a smaller capacitor area, an alternating current is fed. An alternating current is taken from the other small capacitor area. By a finger arranged on the operating side of the capacitive arrangement is detuned, which can be evaluated by a suitable evaluation and recognized as "operation" of the capacitive touch switch.

A further embodiment of a capacitive touch switch is known from document EP 1 416 636 A2, in which a foam body has electrically conductive regions with a sensor element surface and insulating regions which are provided alternately in the direction of extension of a glass ceramic plate. This creates a kind of "strand material" from which adjacent capacitive touch switches can be made.

It is also known from EP 0 859 467 B1 to provide a capacitive touch switch with a sensor key forming one pole of a capacitor, wherein the sensor key consists of a flexible, spatially extended, raumformveränderli- and electrically conductive material which is mounted on a circuit board is applied and bridged the distance between a cover plate and the board, wherein a compressive stress is maintained. From the document DE 10 2004 038 872 Al a touch switch for an operating device of an electrical appliance such as, for example, a hob is also known. The switch has a sensor element with two sensor surfaces, each having one or more triangular faces. The sensor surfaces are controlled by drive signals and experience a contact with a finger a coupling corresponding to a part of the covered area. The remaining signal strength is compared in a microcontroller to determine the location of the touch as a function of the ratio of the remaining signal strengths and covered areas to each other.

Against the above background, it is the object of the invention to provide an improved operating arrangement that can be produced inexpensively and efficiently, even in large quantities.

This object is achieved in the aforementioned operating arrangement in that the sensor element is formed as a planar element which extends over a length which is at least twice as long as the thickness of a human finger.

Such a sensor element can be produced inexpensively and connect structurally favorable with the aperture. Furthermore, it is possible by the relatively large extension in the length direction to realize not only a switch function by means of the sensor element, but a plurality of switch functions and / or a kind of slider (potentiometer).

The task is thus completely solved.

It is particularly advantageous if the contact arrangement has at least one contact section which connects the sensor element at one end to the printed circuit board. In this way it is possible to pick off electrical signals at the ends of the sensor element which represent a measure of the position at which an object such as a finger is located with respect to the sensor element. Preferably, in each case at least one contact section connects the two ends of the sensor element to the printed circuit board.

It is particularly advantageous if the at least one contact section is formed integrally with the sensor element.

This allows cost-effective installation and reduces storage costs.

According to a further preferred embodiment, the sensor element has at least one impedance variation section over its length, by means of which the impedance of the sensor element is influenced in such a way that surfaces associated with the impedance variation section can be distinguished from one another as discrete control surfaces.

In other words, by means of an impedance changing section, a kind of resistance jump is locally realized in the sensor element, which in turn serves to better distinguish between discrete operating surfaces. This is useful in the evaluation of signals that are tapped from the ends of the sensor element. That is, the impedance changing section causes a signal jump if an object (finger) is moved over the length of the sensor element and over such an impedance varying section.

According to a preferred embodiment, the impedance changing section is formed by changing the width of the sensor element.

A constriction of the sensor element (that is, a narrow portion) increases the capacitive resistance at the operating side, thus facilitating in the evaluation of signals that a distinction is made between discrete operating surfaces. According to a further embodiment, the impedance changing section is formed by a step section, in which the sensor element has a step emerging from the surface.

Such a step leads to an increase of the capacitive resistance. A step section can also be combined with a variation of the width of the sensor element.

Overall, it is also advantageous if the circuit board is held by holding means at a predetermined distance from the inside of the diaphragm, wherein the contact arrangement has at least one contact portion which is formed elastically in the direction of the distance, and / or wherein the circuit board is resiliently biased or of the holding means is held elastically.

This measure ensures that the electrical resistance at the transition from the sensor element to the contact section and / or from the contact section to the circuit board is kept as low as possible. As a result, a signal corruption can be avoided. In particular, it can be achieved that no air gap arises between the sensor element and the contact section or between the contact section and the printed circuit board, which would considerably increase the capacitance and considerably complicate the evaluation of signals.

It is particularly advantageous if the contact section has an elastic element such as a spring.

In this embodiment, the contact portion is formed either as a separate element from the sensor element or an elastic E element (such as a spring, a foam element, a TPE element, etc.) is integrally formed on the sensor element and integrally formed therewith. Namely, according to a further embodiment, the material of the sensor element and a contact portion integrally connected thereto are elastically deformable.

The contact portion does not necessarily have a spring shape, but may also be solid or formed as a hollow portion.

Overall, it is also preferred if the sensor element lies flat against the inside of the panel. In this way it can be achieved that a dielectric in the form of the material of the diaphragm is realized between the sensor element and the operating side of the diaphragm, which forms a part of the capacitor between the sensor element and a finger touching the operating side.

It is particularly preferred if no air gap is present between the planar sensor element and the inside of the diaphragm. In this way, for example, it can be safely distinguished between a state in which the finger is spaced from the operating side (in which case there is an air gap with a relatively low dielectric constant between the finger and the diaphragm), and a state in which the Finger touches the operating side of the diaphragm (in which case between the finger and the sensor element only acting as a dielectric diaphragm of the electrically insulating material is present, which preferably has a clearly higher dielectric constant).

According to a further alternative embodiment, the sensor element is integrated as a conductive portion in the diaphragm.

This makes it possible for the outside of the sensor element to be directly accessible in the region of the diaphragm or from its operating side. This may possibly lead to improved detection sensitivity and / or evaluability. It is conceivable that the sensor element and the diaphragm are integrated with each other such that a substantially continuous or flush operating side is formed. It is also preferable if the integration is such that the interface between the Sensor element and the diaphragm is impermeable to liquids and / or gases. It is generally conceivable that the sensor element is made of the same basic material as the diaphragm, and is designed only as a sensor element in the "sensor region", for example by adding electrically conductive materials, However, it is also possible to use the sensor element and the sensor element Aperture separately form and then integrate with each other.

According to a further preferred embodiment, the sensor element is made of a conductive plastic.

In this way, the sensor element can be produced inexpensively for a. On the other hand, an integration in the panel and / or attachment to the panel is comparatively easy to implement. Because it is particularly preferred if the sensor element and the diaphragm are made in 2K injection molding.

In this embodiment, both the sensor element and the diaphragm each consist of a plastic material and are produced in the so-called 2K injection molding process, that is, essentially in one step, but of different materials. It is understood that the sensor element and the diaphragm after the manufacturing step are usually inextricably linked, so that assembly and storage costs are minimized.

Furthermore, it is preferred if a planar section of the sensor element and at least one contact section connected thereto are produced by 2K injection molding.

In this embodiment, it is possible that the planar portion and the contact portion of the sensor element are made of different plastics. In the 2K injection molding process, these different materials are processed in such a way that subsequently a single sensor element is made of two different materials. Before the above background, it is also understood that it is also conceivable that the planar portion of the sensor element, the contact portion connected thereto and the diaphragm are produced by 2K injection molding or, when using different materials for all three components, in 3K injection molding ,

According to a particularly preferred embodiment, the planar sensor element is U-shaped in the surface, wherein the contact portions are arranged adjacent to each other at the ends of the U-legs.

Overall, this leads to a simplified contacting between the sensor element and the printed circuit board and also allows the sensor element to define discrete operating sections which are arranged in the manner of a matrix. In other words, such a sensor element is not limited to a row (row) of discrete operating surfaces. In a further embodiment, it is also possible to form the sensor element overall meander-shaped, so that it consists of several U-shaped individual segments.

According to a further preferred embodiment, this contact arrangement has four contact sections, two of which are each connected to the two ends of the sensor element.

In this embodiment, the contact arrangement allows the use of the so-called Mehrleitermesstechnik. Although in principle two conductors for measuring the position of a finger with respect to the sensor element are possible at each end, the additional conductors at the ends make it possible to eliminate errors in the measurements (in particular systematic errors).

Overall, it is further understood that the sensor element can be realized in high-impedance design. A high-resistance conductive material may be, for example, a plastic, to which conductive material (eg carbon black) is attached. With the operating arrangement according to the invention can be realized capacitive and / or resistive sensor arrangements or control modules. The associated technology for detecting capacitive and / or resistive changes is well known and therefore not described in detail herein. Reference is hereby made to the content of the application filed by the same Applicant on the same day as the present application entitled "Apparatus and Method for Positioning with Reference to a Surface." Accordingly, the content of this copending application is intended to be exhaustive.

Generally, such an operating arrangement is based on the detection of the presence or absence of an object, such as a human finger, by field-electrical interaction effects. Decisive here is an electrical property of the human body, wherein the human body against mass in particular a not inconsiderable capacity of typically 120 pF to 150 pF forms.

The sensor element can be connected to the diaphragm by any desired method. For example. For example, the sensor element can be glued to the inside of the panel. The sensor element may also be a foil with a corresponding coating.

Furthermore, it is conceivable that the sensor element is injected behind the diaphragm. Furthermore, it is conceivable that the sensor element is realized via printing process with conductive printing materials on the inside of the diaphragm. Hot embossing with conductive materials is also possible. Another possibility of implementation is by laser structuring on the inside of a suitable diaphragm, wherein a conditionally conductive zone is generated. This zone can then possibly be galvanically reinforced.

According to a second aspect of the present invention, a sensor arrangement with a non-electrically conductive carrier foil, a flat sensor element, made of a conductive material, fixed to the carrier film and formed as a sheet-like element which extends over a length which is at least twice as long as the thickness of a human finger, wherein on the opposite side of the sensor element of the support film defined a metal foil is.

In this embodiment, the sensor arrangement may be designed as a keyboard foil, with a number of several keys, which are distributed over the length of the sensor element, and preferably only two electrical connections (in contrast, piezo membrane keyboards generally require one connection per key). ,

Through the metal foil, the optics of the sensor arrangement can be used and can be applied to any support materials.

If the carrier film is designed to be elastic, a flexible region for connection to a printed circuit board can be provided via the carrier film. Furthermore, it is conceivable, by pressing the metal foil at one point of the sensor surface, to short-circuit this area to ground (capacitance) so that the same effect occurs as if the sensor element were directly based.

It is advantageous here if the sensor arrangement has an adhesive film layer in order to attach the sensor arrangement, for example, to a panel of an electrical device.

Although the sensor arrangements according to the invention are preferably used to operate electrical appliances, it should be understood that the invention is not intended to be limited to this application. It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:

Figure 1 is a schematic sectional view through a household electric machine in the form of a washing machine with an operating arrangement according to the invention according to an embodiment of the present invention.

2 shows an operating arrangement according to a further alternative embodiment of the invention;

Fig. 3 is a plan view of a sensor arrangement of the operating arrangement of

Fig. 2;

4 shows a schematic perspective view of a further embodiment of an operating arrangement according to the invention;

Fig. 5 is a side view in the longitudinal direction of the operating arrangement of Fig. 4;

Fig. 6 is a sectional view taken along the line VI-VI in Fig. 5;

Fig. 7 is a sectional view taken along the line VII-VII in Fig. 6;

8 shows a perspective view, comparable to FIG. 4, of a further alternative embodiment of an operating arrangement according to the invention; FIG. 9 is a view corresponding to FIG. 6 of the operating arrangement of FIG. 8; FIG.

FIG. 10 shows a schematic perspective view corresponding to FIG. 4 of a further embodiment of an operating arrangement according to the invention; FIG.

FIG. 11 shows a sectional view corresponding to FIG. 6 through the operating arrangement of FIG. 10; FIG.

12 shows a schematic partial view in perspective representation of a further alternative embodiment of an operating arrangement according to the invention;

13 shows a schematic perspective partial view of a further embodiment of an operating arrangement according to the invention;

14 shows a perspective sectional view through a further embodiment of an operating arrangement according to the invention; and

15 shows a schematic perspective illustration of a sensor arrangement based on an electrically non-conductive carrier foil;

Fig. 16 is a bottom view of the sensor assembly of Fig. 15 (without adhesive film); and

17 shows an alternative embodiment of a sensor arrangement, each having two contact sections at the ends of a sensor element for implementing the multi-conductor measuring technique.

In Fig. 1, an exemplary electrical device in the form of a washing machine is generally designated 10. The washing machine 10 has a housing 12, inside half of which a washing drum 14 and an electric motor 16 are mounted for driving the washing drum 14.

Furthermore, the washing machine 10 has an operating arrangement 20.

The control assembly 20 includes a bezel 22 made of an electrically non-conductive material. The aperture 22 usually forms part of the housing or is integrated in the housing 12. Furthermore, the operating arrangement 20 includes a printed circuit board 24 which is mounted within the housing 12 of the washing machine 10. An operating side of the shutter 22 (that is, an outer side) is designated B, an opposite inner side with I.

The circuit board 24 is mounted in a preferred embodiment of the diaphragm 22, by means of schematically indicated holding means 26 on the inner side I of the diaphragm 22nd

The operating arrangement 20 further includes a sensor arrangement 30. The sensor arrangement 30 has a planar sensor element 32 which is fixedly connected to the panel 22. More specifically, the sensor element 32 is preferably connected flat to the inside I of the diaphragm 22 without forming an air gap.

Between the inside I of the diaphragm 22 and an opposite surface of the circuit board 22, a distance A is set by the holding means 26.

The thickness of the sensor element 32 is generally much smaller than the distance A. For the electrical connection of the sensor element 32 to the circuit board 24, a contact arrangement 34 is provided.

The circuit board 24 further includes evaluation electronics and the like in a conventional manner, so that the sensor assembly 30 is capable of at least one, preferably to detect a plurality of positions of an object 36, such as a human finger, on the outside of the bezel 22.

Preferably, the detection by the finger 36, the operating side B of the diaphragm 22 touches, so that between the finger 36 and the sensor element 32, only the material of the diaphragm 22 is present, which is formed, for example, of a plastic having a dielectric constant greater than 1 ,

In this case, the sensor element 32 extends over a certain length L (shown in vertical arrangement in FIG. 1) which is greater than twice the thickness of a human finger 36. Accordingly, it is preferably possible to use the sensor arrangement 30 for at least two different positions of the finger 36 with respect to the longitudinal extent of the sensor element 32 to detect.

The contact arrangement 34 is designed such that a substantially air-gap-free electrical connection is established between the sensor element 32 and the printed circuit board 24 (more precisely contact pads on the printed circuit board 24). This can be achieved in particular by giving the elements involved a certain elasticity. For example. For example, contact portions between the sensor element 32 and the circuit board 24 may be formed of an elastic material. It is also possible to configure the holding means 26 in such a way that the printed circuit board 24 is pressed elastically in the direction of the aperture 22. In general, it is also conceivable that the circuit board 24 itself has certain elastic properties.

FIGS. 2 to 14 show alternative embodiments of operating arrangements 20 and sensor arrangements 30 according to the present invention. The embodiments explained below correspond in terms of structure and with regard to the mode of operation of the embodiment explained above to an operating arrangement 20 according to the invention. Therefore, only differences will be explained below. Identical or mutually corresponding elements are provided with the same reference numerals. In Figures 2 and 3, an operating arrangement 20 is shown, in which the sensor element 32 is U-shaped in the surface, wherein ends of U-legs 44, 46 of the sensor element 32 via integrally molded contact portions 40 and 42 with the circuit board 24th are connected.

In this embodiment, the contact portions 40, 42 may be arranged relatively close to each other, which facilitates the contact with the circuit board 24.

FIGS. 4 to 7 show a further embodiment of a control arrangement according to the invention. The holding means 26 are formed in this Ausruhrungsform by four locking tongues 50, which extend perpendicularly from the inside I of the panel 22 and engage around the circuit board 24 latching. The contact portions 40, 42 are dimensioned and formed from such a material that the printed circuit board 24 is pressed into the locking tongues 50 with a certain compressive force due to the elastic properties, so that overall a stable mounting of the printed circuit board 24 is achieved.

On the inside of the diaphragm 22, a plurality of locking lugs 52 is further provided, which receive the elongated sensor element 32 between them. In other words, in the present embodiment, the sensor element 32 can be clipped onto the inside I of the diaphragm 22. It is understood that in addition a compensation layer, an adhesive layer or the like between the sensor element 32 and the inner side I of the diaphragm 22 may be provided.

Finally, the sensor element 32 is formed in the longitudinal extent with a plurality of narrow portions 53, each having a relatively small width 54, and a plurality of wide portions 55, each having a relatively large width 56. The narrow portions 53 represent impedance changing sections in the present case, since a resistance jump is established by them. In particular, the capacitive resistance to the finger in the region of the narrow sections 53 may increase. Consequently, when evaluating sensor signals derived in the region of the two contact sections 40, 42, it is better possible to distinguish between discrete operating surfaces 58 which are respectively formed around one of the wide sections 55.

Of course, the other way around, the wide sections 55 can also be understood as impedance changing sections. Also, the discrete control surfaces 58 may be assigned to the narrow sections 53 instead of the wide sections 55.

FIGS. 8 and 9 show a further embodiment of an operating arrangement 20 according to the invention. The operating arrangement 20 of FIGS. 8 and 9 corresponds in many respects to the operating arrangement of FIGS. 4 to 7. In the following, only the differences are explained.

Thus, in the operating arrangement 20 of FIGS. 8 and 9, a plurality of impedance changing sections in the form of step sections 60 are formed. In other words, the on-surface sensor element 32 is provided with steps 62 which emerge from the surface of the sensor element 32. The steps point towards the printed circuit board 24 and are formed on transverse struts 64 which, for example, can be formed in one piece with the diaphragm 22. It is thereby achieved that the sensor element 32 is also connected to the diaphragm 22 in the area of the step sections 60 in an air-free manner.

It can also be seen in FIG. 9 that limit stops 66 can be provided on the operating side B of the diaphragm 22, which serve to distinguish discrete operating surfaces 58 which are delimited from one another for a user.

Although not shown in FIG. 9, the constraints 66 may be approximately square, rectangular, or round in shape. FIGS. 10 and 11 show a further embodiment of an operating arrangement 20 according to the invention.

The operating arrangement 20 of FIGS. 10 and 11 combines features of the sensor arrangements 20 of FIGS. 4 to 7 and 8, 9, so that only differences will be explained below.

In the operating arrangement 20 of FIGS. 10 and 11, impedance changing sections include both narrow sections 53 between wide sections 55 and step sections 60. In this case, the step sections 60 are approximately triangular or trapezoidal in cross section.

Furthermore, instead of the integrally provided with the sensor element 32 contact portions 40, 42 is provided that the sensor element 32 with the circuit board 24 via contact portions 40, 42 in the form of springs, in particular coil springs, contacted or connected.

For this purpose, as shown, a spring receptacle 68 may be provided on the inside of the panel 22.

FIG. 12 shows a further alternative embodiment of an operating arrangement 20, wherein integrally spring sections 40 for forming contact sections are integrally formed on a sensor element 32. In the case of Fig. 12, the spring portion 40 is formed as a helical spring. In Fig. 13, an alternative embodiment is shown in which the contact portions 40, 42 are formed as corrugated springs.

Finally, FIG. 14 shows a further alternative embodiment of an operating arrangement according to the invention, wherein a sensor element 32 is integrated as a conductive section in the panel 22 so that an outside of the sensor element 32 is flush with an operating side B of the panel 22. It is understood that the interface between the sensor element 32 and the diaphragm 22 should be made watertight.

FIGS. 15 and 16 show an alternative embodiment of a sensor arrangement 30 'according to a further aspect of the present invention.

The sensor arrangement 30 'has an electrically non-conductive carrier foil 70, which may be made of an elastic material. Furthermore, the sensor arrangement 30 'has a planar sensor element 76, which is made of a conductive material, fixed to the carrier film 70 and formed as a planar element which extends over a length which is at least twice as long as the thickness of a human finger ,

The sensor element 76 may generally correspond in shape and characteristics to the sensor element 32 of the previously described embodiments.

The sensor arrangement 30 'furthermore has a metal foil on the side of the carrier foil opposite the sensor element.

The metal foil can on the one hand serve for optical improvement (metal optics). Furthermore, if the carrier film is designed to be very elastic, the metal foil can also be used to short-circuit this region to ground (capacitance) by pressing in the metal foil 72 in the region of a sensor surface. The same effect occurs as if one would touch the sensor element 76 directly.

In general, in this embodiment, it is possible to realize a membrane keyboard with a number of more than one key and only two electrical connections.

The optic is changeable by the metal foil, instead of a metal foil also other cover foils are possible. Preferably, the film sensor assembly 30 'is glued by means of an adhesive film 78 on a control panel. The adhesive film 78 is preferably fixed on the underside, that is to say on the rear side of the sensor element 76.

In Fig. 16, the adhesive sheet 78 is omitted for the purpose of illustration.

In Fig. 17, an alternative operating arrangement 20 is shown, which may correspond in structure and function, for example, the operating arrangement shown in Fig. 1.

Here, too, a planar, elongated sensor element 32 is fixed in the region of a diaphragm 22. At the ends of the sensor element 32, an additional contact portion 40a and 42a are provided in each case in addition to the two contact portions 40, 42.

This operating arrangement 20 is suitable for the use of the so-called multi-wire metrology, in which signals are tapped not only at the contact portions 40, 42 but also at the contact portions 40a, 42a in order to calculate any errors therefrom can. In particular, the systematic error that is caused by the use of the contact sections 40, 42 can be eliminated by the additional contact sections 40a, 42a.

In general, the shape of the sensor elements can be arbitrary. It is also possible to arrange a plurality of sensor elements serially one behind the other, which are each connected to one another via a conductor track. It is also conceivable to arrange two sensor elements at an angle to one another on a surface, for example at an angle of 90 °.

By this measure, an xy-coordinate system is clamped by means of the sensor elements, which makes it possible to detect the presence of a finger at any position of the plane defined by the sensor elements surface (of the xy-quadrant). Consequently, in this embodiment, a sensor surface can be realized in a simple manner with a plurality of sensor keys arranged at any desired location on it.

Claims

claims

First operating arrangement (20) for operating an electrical device (10), in particular a household appliance (10), with a diaphragm (22) made of an electrically insulating material having an inner side (I) and an operating side (B), and with a sensor arrangement (30) for detecting an object (36) on the operating side (B), the sensor arrangement (30) having a printed circuit board (24) and a sensor element (32) arranged on the inner side (I) of the diaphragm (32), which are electrically connected to one another by means of a contact arrangement (34), wherein the sensor element (32) is made of an electrically conductive material and connected to the panel (22),

characterized in that

the sensor element (32) is formed as a planar element which extends over a length (L) which is at least twice as long as the thickness of a human finger (36).

2. Control arrangement according to claim 1, characterized in that the contact arrangement (34) has at least one contact section (40, 42) which connects the sensor element (32) at one end to the printed circuit board (24).

3. Operating arrangement according to claim 2, characterized in that the at least one contact portion (40, 42) is formed integrally with the sensor element (32).

4. Operating arrangement according to one of claims 1-3, characterized in that the sensor element (32) over the length (L) at least one impedance change section (53, 55, 60), by means of which the impedance of the sensor element (32) is influenced in such a way in that the impedance change Section (53, 55, 60) associated surfaces as discrete control surfaces (58) are distinguishable from each other.

5. Operating arrangement according to claim 4, characterized in that the impedance change section (53, 55) by a change in the width (54, 56) of the sensor element (32) is formed.

6. Operating arrangement according to claim 4 or 5, characterized in that the impedance changing portion (60) by a step portion (60) is formed, wherein the sensor element (32) has a step out of the surface step (62).

7. Operating arrangement according to one of claims 1-6, characterized in that the circuit board (24) by holding means (26) at a predetermined distance (A) to the inside (I) of the diaphragm (22) is held, wherein the contact arrangement ( 34) has at least one contact portion (40, 42) which is formed elastically in the direction of the distance (A), and / or wherein the circuit board (24) is elastically biased or elastically held by the holding means (26).

8. Operating arrangement according to claim 7, characterized in that the contact portion (40, 42) has an elastic element.

9. Operating arrangement according to claim 7 or 8, characterized in that the material of the sensor element (32) and an integrally connected thereto contact portion (40, 42) is elastically deformable.

10. Operating arrangement according to one of claims 1 - 9, characterized in that the sensor element (32) flat against the inside (I) of the diaphragm (22).

11. Operating arrangement according to one of claims 1 - 10, characterized in that the sensor element (32) is integrated as a conductive portion in the diaphragm (22).

12. Operating arrangement according to one of claims 1 - 11, characterized in that the sensor element (32) is made of a conductive plastic.

13. Operating arrangement according to one of claims 1 - 12, characterized in that the sensor element (32) and the diaphragm (22) are produced by 2K injection molding.

14. Operating arrangement according to one of claims 1-13, characterized in that a planar portion of the sensor element (32) and at least one contact portion (40, 42) connected thereto are produced by 2K injection molding.

15. Operating arrangement according to one of claims 2-14, characterized in that the planar sensor element (32) is U-shaped in the surface, wherein the contact portions (40, 42) at the ends of the U-legs (44, 46). are arranged adjacent to each other.

16. Operating arrangement according to one of claims 1-15, characterized in that the contact arrangement (34) has four contact portions (40, 42, 40a, 42a), of which two are each connected to the two ends of the sensor element (32).

17. Sensor arrangement (30 ') with a non-electrically conductive carrier film (70), a flat sensor element (76), which is made of a conductive material, fixed to the carrier film and formed as a planar element extending over a length (L) extending at least twice as long as the thickness of a human finger (36), wherein on the sensor element (76) opposite side of the carrier film (70) a metal foil (72) is set fetsge-.

18. Sensor arrangement according to claim 17, with an adhesive film layer to attach the sensor assembly to a diaphragm of an electrical device (10).