Control device for a household appliance with a control knob having a light guide and an infrared transmitter / receiver

Abstract

Operating device (8) for a household appliance (1), comprising an operating element (9) which is held by magnetic force on an operating element receptacle (10) of the household appliance (1) controllable by the operating device (8) and is movable relative to the operating element receptacle (10) and can be removably positioned therefrom, and the operating element (9) has a light guide (22) which has a light coupling region (28) which is arranged further from a lateral edge of the operating element (9) than a light coupling region (29) of the light guide (22), characterized in that the operating device (8) has an infrared transceiver device (17) for selecting a functional subunit (3 to 7) of the household appliance (1), which is arranged with transceiver units (18) below the light guide (22) and is designed for detection through the light guide (22).

Description

[0001] The invention relates to an operating device for a household appliance, comprising an operating element which is held by magnetic force on an operating element receptacle of the household appliance controlled by the operating device and which is movable relative to the operating element receptacle and can be removably positioned therefrom. The operating element has a light guide which comprises a light coupling region which is arranged in the edge of the operating element further away than a light coupling region of the light guide. With such designs of removable operating elements, light guided via the light guide can be guided radially from the inside to the outside and thus also be emitted in the edge region of the operating element.

[0002] Such an operating device is known, for example, from DE 10 2011 083 460 A1. There, it is also provided that the rotational position of the operating element relative to the operating surface can be detected using adjustment magnets, and based on this, a desired operating condition setting of the household appliance is recognized and implemented. The adjustment magnets are arranged in the operating element below the light guide and interact with sensors located in the hob plate.

[0003] From the subsequently published DE 10 2012 200 292 A1, an operating device for a household appliance is known, which comprises an operating element that can be removably positioned on a control element holder of the household appliance. The operating element has a touch area, the contact of which is detected by means of reflected IR radiation.

[0004] DE 10 2012 213 693 A1, also subsequently published, describes an operating device for a household appliance with an operating element that is magnetically held on a control element holder of the household appliance. The operating element has a light guide that extends from a bottom to a top of the operating element.

[0005] DE 10 2006 062 071 B4 discloses an optoelectronic input device for a household appliance. This device comprises a light source, a light detector, and a light guide.

[0006] The object of the present invention is to provide an operating device in which a compact control element is improved with regard to visual information display and position determination. Furthermore, it is an object to provide and improve a household appliance with such an operating device.

[0007] This object is achieved by an operating device and a household appliance according to the independent claims.

[0008] An operating device according to the invention for a household appliance comprises an operating element which is held by magnetic force on an operating element receptacle of the household appliance controllable with the operating device and which is movable relative to the operating element receptacle and can be removably positioned therefrom. The operating element comprises at least one optical fiber which has a light coupling region. The light coupling region is arranged further from an edge of the operating element than a light coupling region of the optical fiber. The optical fiber is therefore arranged and oriented in the operating element such that it guides light from an area closer to a center of the operating element or a correspondingly closer location to a location further away from this center and emits it accordingly.

[0009] A key concept of the invention is that the operating device has an infrared transceiver for determining the position of the operating element. This infrared transceiver comprises transceiver units that are arranged beneath the light guide and, in a particularly advantageous embodiment, are designed for axial detection through the light guide. When viewed in the direction of the longitudinal axis, the light guide thus covers the infrared transceiver units virtually from above. Such a configuration enables a particularly compact design in a direction perpendicular to a longitudinal axis of the operating element, since the light guide and the receiver are positioned virtually one below the other. The infrared transceiver also creates a detection mechanism that operates with great precision.This combination of the spatial arrangement of the receiving device and the optical fiber on the one hand and the conceptual design of the transmitting-receiving device on the other hand, namely operating on the basis of infrared light, also creates a design in which the infrared radiation can be emitted upwards through the optical fiber without the light in the optical fiber being impaired, and in addition the detection of the infrared radiation from above through the optical fiber to the infrared transmitting-receiving device below is then also possible.

[0010] Preferably, the control element has a base through which the light guide is covered from below. In particular, a light coupling area of ​​the light guide is covered from below by the base. With such a design, the light guide is positioned so as to be protected from below, so that no damage, such as scratching or the like, can occur to the light guide when the control element is removed or put back on, or when the control element is moved relative to the control element holder. Furthermore, such a design also protects the light guide from contamination, particularly in the light coupling area. Functional reliability and the maximum possible light coupling are thus ensured. This can then also be maintained permanently.In addition, such a design also makes the operating element as such mechanically stable and robust, since a preferably completely closed base is designed, which preferably forms a housing for the operating element with a cover.

[0011] Preferably, the control element has a base that is permeable to light in the spectral range visible to humans and to the infrared radiation range, at least in the areas where the light can be coupled into the optical fiber and in the areas where the transmitting / receiving units detect through the optical fiber. This facilitates the aforementioned advantages with regard to both the mechanical and optical aspects.

[0012] Preferably, the base is made of a plastic, preferably PSU (polysulfone) or PESU (polyethersulfone). These are particularly advantageous plastics with regard to mechanical and optical properties and are also very robust against extremely fluctuating temperature influences, as is the case, for example, with a cooking appliance, such as a hob.

[0013] These plastic materials are extremely heat-resistant and also have the required transparency in the spectral range visible to humans and in the infrared radiation range.

[0014] Preferably, the light guide is designed as a ring-disk-shaped body, on the edge of which an upwardly raised ridge forms the light output region. This design of the light guide enables a very flat design of the light guide from the light input region to the ridge forming the light output region, which, thanks to the ring structure, is also very stable and rigid. The ridge as the light output region precisely defines the light output region geometrically and in terms of orientation, and in this context, it also permanently retains its position, so that the direction of light emission from the light output region is very precise.

[0015] In particular, the light guide is designed as a single piece.

[0016] The control element is preferably designed with a casing wall, which covers the light guide all the way around the sides and on which a cover of the control element sits. This design ensures that the light guide is also protected from unwanted influences such as scratches or contamination. This side wall thus also creates a support element for additional components of the control element, which then define a housing. This ensures the mechanically stable design of this housing.

[0017] In particular, if the side wall is opaque, undesirable optical effects and unwanted light leakage can be avoided.

[0018] Preferably, the transmitting / receiving units are each enclosed laterally to prevent stray light. This is a very advantageous design because it allows the largest possible amount of light emitted by the light source to be guided to the light coupling area of ​​the light guide in a very targeted and directed manner. On the other hand, it prevents other components of the control element from having their functionality impaired by this light. In particular, this also prevents unwanted heating of other components by the light from the light source. In particular, this also achieves separation from the transmitting / receiving units. In particular, a ring is provided as such an enclosure, which surrounds the light sources in the direction of rotation around the longitudinal axis of the control element.Preferably, this ring of the housing is arranged between the light sources and the transmitting-receiving units, viewed in the direction perpendicular to the longitudinal axis of the control element.

[0019] The light sources are preferably arranged very close to a center point of the operating element. For this purpose, it is preferably provided that a holding magnet is arranged centrally, which is preferably cylindrical. In the radial direction and thus in a direction perpendicular to the longitudinal axis of the operating element and thus also of the operating device, a plurality of light sources are then positioned directly adjacent to this holding magnet and circumferentially around it. It can also be provided that a thin partition wall, for example made of plastic, is arranged between the light sources and the holding magnet. As already explained, the ring then sits as a housing on the side opposite the light sources when viewed in the radial direction, so that the light sources are arranged in a ring-like recess or groove.This recess, or the height of these walls of the enclosure, is preferably dimensioned so that the light sources are completely recessed within them. This particularly emphasizes the aforementioned advantages regarding the prevention of stray light.

[0020] It can be provided that the inner sides of these partition walls or this annular web of the enclosure are partially reflective, so that the light emitted by the light sources is largely reflected back to the light coupling area of ​​the optical fiber, thus allowing a very high amount of emitted light to reach this optical fiber. The reflective design of these inner sides can be achieved by a film or a corresponding coating.

[0021] In particular, it is provided that this holding magnet external to the control element and / or a possibly present partition, as well as the light sources and the optionally present housing, are arranged outside the control element, in particular underneath it. The arrangement of the mentioned elements can be arranged underneath a household appliance panel having the control surface, in particular a hob panel, or at least partially within this household appliance panel. The transceiver units are also arranged underneath or at least partially within this household appliance panel. These mentioned components are preferably arranged on a circuit carrier or a circuit board that is positionally arranged underneath this household appliance panel.

[0022] Preferably, a cover of a housing of the control element is formed at least partially, in particular entirely, from a glass or glass-like material. The material is preferably designed such that light can pass through. In particular, the material of this cover is chemically tempered glass. Such a design particularly meets the requirements with regard to mechanical robustness, scratch protection, and sufficient transparency for the respective spectral ranges.

[0023] Preferably, a film or print that is permeable to infrared and light in the spectral range visible to humans is applied to the underside of this cover facing the light guide. Such a film or print is preferably formed in a surface area of ​​the underside formed by an outer surface ring.

[0024] Such a design allows the light emitted relatively far outward from the light output area to be emitted unhindered through the cover from the control element. Visual information regarding operating condition settings and the like can thus be presented to the user in a very comprehensive and easily understandable manner. Accordingly, the processing of infrared rays via this surface area of ​​the cover is also facilitated.

[0025] Preferably, the cover is opaque in the areas that, when viewed vertically, are located above a light coupling area. This can prevent unwanted light leakage and thus undesirable optical effects or even misinterpretable optical information from being transmitted to a user via the cover of the control element. Preferably, when viewed radially, this area, which is opaque to light, directly borders the surface ring, which is transparent to light in the visible spectral range and to infrared rays.

[0026] Preferably, the surface area of ​​the underside of the cover that is opaque to light has rotation detection markings by means of which the direction of rotation of the operating element relative to the operating surface can be detected. Depending on such detection of the direction of rotation and a corresponding length of this rotational movement, the setting of a desired operating parameter value can be detected.

[0027] In this context, such a rotation of the control element can, for example, be used to set a cooking level of a cooking zone of a cooking appliance.

[0028] Preferably, these markings are spaced and equidistant from one another in the circumferential direction around the longitudinal axis of the control element. For example, these markings can be designed as white prints or varnishes.

[0029] In a preferred embodiment, it is provided that the cover is opaque in the areas which, when viewed vertically and thus when viewed in the direction of the longitudinal axis of the operating element, are arranged above a light coupling area.

[0030] In particular, it is provided that light sources are arranged in a straight line below a light coupling area of ​​the optical fiber when viewed in the direction of the longitudinal axis of the operating device. This prevents extensive light deflection and routing to the light coupling area, and the shortest possible path between the light source and the light coupling area is achieved.

[0031] It is preferably provided that the light sources are arranged in an annular channel, the walls of which, which preferably represent a partition wall and a wall of the housing, are formed with heights which are greater than the light source heights.

[0032] The light sources may preferably be light-emitting diodes.

[0033] A holding magnet is also positioned centrally in the control element, which interacts with the holding magnet external to the control element to hold the control element on the operating surface. This holding magnet internal to the control element is preferably arranged in a receptacle, which can, for example, also be designed integrally with the base. The light guide, in particular with its light coupling region, is arranged radially adjacent to this holding magnet, in particular adjacent to the outer side of the receptacle for the holding magnet. It then preferably extends radially to the inner side of the aforementioned casing wall. This enables maximum radial light conduction.

[0034] Furthermore, it can also be provided that the operating element has a closing ring which surrounds the casing wall and the outer edge of the lid all the way around, preferably with a wrap-around area or a collar which lies on the top or outside of the lid and contacts the lid accordingly, enclosing it and sitting thereon.

[0035] This end ring can be made of stainless steel or plastic, for example, so that in addition to its holding function, it is also designed to be wear-resistant and also takes design aspects into account.

[0036] Due to the specific arrangement of the light guide and the infrared transmitting and receiving device, the infrared signal for selecting a sub-area or sub-unit of the household appliance, in particular a cooking zone of a hob, can be guided axially through the light guide and then correspondingly evaluated on the circuit board on which the transmitting and receiving units are arranged. In this context, if a user touches, for example with a finger, preferably on the top side of the cover of the control element, the selection of a desired sub-unit, in particular a cooking zone, is recognized at specific points. This selection can then be visually indicated by a locally specified light guide from one or more light sources to the light guide, so that the user is also shown the selection of this sub-unit locally and visually on the control element itself.The optical display via the light sources and the light guide can be used in addition to or instead of other operating condition settings of the household appliance.

[0037] Further features of the invention emerge from the claims, the figures, and the description of the figures. 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 respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also to be considered encompassed and disclosed by the invention that are not explicitly shown and explained in the figures, but which emerge and can be produced by separate combinations of features from the explained embodiments.

[0038] Embodiments of the invention are explained in more detail below with reference to schematic drawings. They show: Fig. 1 a perspective view of an embodiment of a household appliance according to the invention; Fig. 2 a perspective sectional view of the household appliance according to Fig. 1; Fig. 3 a sectional view of the design in Fig. 2; Fig. 4 a plan view of subcomponents of the operating device according to Fig. 1 and Fig. 2, as installed in the household appliance; and Fig. 5 a view of an underside of a cover of the operating element of the operating device according to Fig. 2 and Fig. 3.

[0039] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0040] In Fig. Figure 1 shows a schematic representation of a household appliance configured as a hob 1. The hob 1 comprises a hob plate 2 configured as a household appliance plate, which can be made of glass or glass ceramic. On an upper side 2a of the hob plate 2, four cooking zones 3, 4, 5, 6, and 7 are shown, merely by way of example, in terms of number, position, and shape.

[0041] Under the hob plate 2 are Fig. 1, heating units (not shown) are arranged to heat the surface areas of cooking zones 3 to 7, whereby preparation vessels with food for preparation can be placed on cooking zones 3 to 7. In this context, heating units are to be understood as, for example, both radiant heaters and inductors, in which energy is introduced to heat the food in preparation vessels. With inductors, as is known, cooking zones 3 to 7 in the form of the material of the hob plate are not heated directly, but only the preparation vessel is heated directly through electromagnetic interaction.

[0042] The hob 1 further comprises an operating device 8, which in the exemplary embodiment is arranged in the front area of ​​the hob plate 2. The operating device 8 comprises an operating element receptacle 9, which in the exemplary embodiment is arranged in the hob plate 2. A operating element 10 can be positioned in the operating element receptacle 9. In the exemplary embodiment, the operating element 10 is disc-shaped or disk-shaped and can be non-destructively removed and reattached to the hob plate 2, in particular the operating element receptacle 9.

[0043] In Fig. 2 shows a sectional view along the section line II-II of the hob 1 in the area of ​​the operating device 8. For the sake of clarity and to also identify the components arranged under the hob plate 2, the hob plate 2 is shown in Fig. 2 not shown.

[0044] The operating device 8 comprises a circuit carrier 11 beneath the hob plate 2, on which a holding magnet 12 is arranged. The holding magnet 12 is arranged in a receptacle 13, which, as a partition 13, extends at least partially around an axis A, which represents the longitudinal axis of the operating device and thus also of the operating element 9. In a direction perpendicular to the axis A and thus in the radial direction, a plurality of light sources 14 are positioned directly adjacent to the holding magnet 12 and the partition 13. The light sources 14 are spaced apart in the circumferential direction around the axis A and arranged equidistant from one another. The light sources 14 are preferably light-emitting diodes.

[0045] Again radially outwardly adjoining the light sources 14 is a further wall 15 which is assigned to a housing for specific components. The inner receptacle 13 with the wall shown also belongs to this housing. In the exemplary embodiment, the wall 15 is part of a circumferential ring 16. The wall 15 or the ring 16 provides a shield against scattered light, so that the light from the light sources 14 does not radiate outwards in an undesirable manner. The operating device 8 further comprises an infrared transceiver 17 which has a plurality of transceiver units 18, five in the exemplary embodiment. The number of transceiver units 18 corresponds to the number of cooking zones 3 to 7. The transceiver units 18 are each enclosed by housings 19 ( Fig. 2) are also surrounded laterally accordingly, so that the detection is improved and no scattered light effects or the like can have an effect here either.

[0046] In addition, the operating device 8 also comprises detectors 20 ( Fig. 5) and 21, by means of which a rotation detection of the operating element 9 about the rotation axis or longitudinal axis A relative to the upper side 2a and thus also to the operating element receptacle 10 can be detected.

[0047] As can be seen from the illustration in Fig. 2, the transmitting / receiving units 18 are arranged within the dimensions of the operating element 9 and are positioned in particular under a light guide 22, viewed in the vertical direction and thus in the direction of the axis A.

[0048] The light guide 22 is arranged inside the control element, wherein a housing of the control element 9 is formed by a cover 23 and a base 24 as well as a casing wall 25. The casing wall 25 is in particular formed integrally with the base 24. On the inside of the base 25, a receptacle 26 for a holding magnet 27, which is arranged in the control element 9, is also formed. The holding magnet 27 is also arranged centrally in the control element 9 and is designed to interact with the holding magnet 12. The circuit carrier 11 with its elements arranged thereon, as shown in Fig. 2, is arranged below the hob plate 2, whereas the control element 9 can be attached to the control element holder 10 via the upper side 2a.

[0049] The light guide 22 comprises a light coupling region 28, which is arranged closer to the axis A than a light coupling region 29. The light guide 22 is designed as an annular disc, with an upwardly extending raised web 30 formed at its radially outer end facing away from the axis A, which then forms the light coupling region 29 at its end. The light sources 14 are formed in a straight line below the light coupling region 28, viewed in the direction of the axis A.

[0050] The base 24 is formed over its entire surface and thus completely covers the light guide 22 from below. The light from the light sources 14 is thus first emitted through the base 24 and then to the light coupling area 28. The base 24 is preferably made of a material that is permeable to light in the spectral range visible to humans as well as to infrared rays. In particular, the base 24 is made of a plastic, preferably PSU or PESU.

[0051] By means of the infrared transceiver device 17 and thus also the transceiver units 18, which operate on the basis of the detection of infrared rays, an embodiment is formed which is designed to detect a selection of a functional subunit of the hob 1. In particular, this device 17 is designed to detect the selection of a cooking zone 3 to 7. For this purpose, each of the infrared transceiver units 18 is linked to one of the cooking zones 3 to 7 with regard to the desired selection, which is then recognized and evaluated by a control unit (not shown), and the heating unit assigned to the respective cooking zone 3 to 7 is then activated. In this context, it is provided that a user, for example, locally grasps a top side 31 of the lid 23 with a finger or places the finger accordingly, so that this is locally recognized via the infrared transceiver units 18.If, for example, the cooking zone 4 is to be selected, the user places a finger on the top side 31 at the locally specified and provided surface on the top side 31, which is located vertically above the associated infrared transmitting / receiving unit 18. For example, this can be done in the context according to the top view of the circuit carrier 11 in . Fig. 4 the lower left infrared transmitter-receiver unit 18. The direction of rotation around the axis A, which is Fig. 4 runs perpendicular to the plane of the figure, the following infrared transmitting-receiving unit 18 is then assigned to the cooking zone 5, wherein the infrared transmitting-receiving unit 18 which then follows in the direction of rotation of the axis A is assigned to the cooking zone 3, the then following infrared transmitting-receiving unit 18 is assigned to the cooking zone 6 and which finally in the direction of rotation of the axis A in Fig. 4 infrared transmitter-receiver unit 18 arranged to the right, front and bottom is assigned to the cooking zone 7.

[0052] In the exemplary embodiment, the cover 23 is made of chemically hardened glass and is locally opaque and, at other local surface areas, permeable to light in the spectral range visible to humans and to infrared rays.

[0053] Furthermore, the operating element 9 comprises an annular end element 32, which circumferentially surrounds the operating element 9 and thus also the casing wall 25 and also engages around a side edge 33 of the cover 23. Furthermore, this end element 32 comprises an upper flange or a support web 34, which rests on the upper side 31. This end element 32 is preferably made of stainless steel or plastic.

[0054] The light guide 22 is completely covered by the cover 23 with its coupling-out region 29, wherein the partial surface of the cover 23 which is arranged vertically above the light coupling-out region 29 is permeable to light in the visible spectral range and also to infrared rays.

[0055] For the design of the respective partial surfaces of a bottom side 34 of the cover 23, as shown in Fig. 5, which shows a view of the underside 34 of the lid 23, a ring-shaped print or a film 35 is provided which is permeable to light in the visible spectral range and to infrared rays. Radially inwardly adjoining this film 35, which forms the surface of the underside 34 as an outer circumferential ring, is a printed area 36 or area provided with a film which is opaque to infrared rays and light in the visible spectral range. In this surface area, a plurality of markings 37 are arranged adjacent to and spaced from one another in the direction of rotation around the axis A, which markings are particularly white. By means of these markings 37, the direction of rotation around the axis A is determined by means of the detectors 20 and 21, and from this the desired setting of an operating parameter of the selected functional sub-unit in the form of the cooking zones 3 to 7 is set.In particular, this direction and range of rotation sets the cooking level of the selected cooking zone 3 to 7.

[0056] The markings 37 are radially positioned such that when the control element 9 is rotated about the axis A, they pass over the detectors 20 and 21, thus allowing the direction of rotation and the desired value of the cooking level to be recognized and set more quickly. This depends in particular on how many such markings 37 pass over or past at least one detector 20, 21.

[0057] In Fig. 3 is a sectional view of the Fig. 2, where the hob plate 2 is shown with the control element 9 attached. The relative positional arrangements of the individual components of the control element 9 and the components external to the control element can be seen both in the direction of axis A and in the perpendicular direction thereto. List of reference symbols 1 household appliance 2 hob plates 2a top 3 cooking zones 4 cooking zones 5 cooking zones 6 cooking zones 7 cooking zones 8 Control device 9 Control element holder 10 Control element 11 circuit carriers 12 Holding magnet 13 Partition wall 14 Light source 15 Wall 16 rings 17 Transceiver 18 transmitter-receiver units 19 enclosures 20 detector 21 Detector 22 light guides 23 lids 24 Floor 25 shell wall 26 recording 27 Holding magnet 28 Light coupling area 29 Light output area 30 jetty 31 Top 32 End element 33 margin 34 Bottom 35 slides 36 Area 37 markings A axis II-II section line

Claims

[1] Operating device (8) for a household appliance (1), comprising an operating element (9) which is held by magnetic force on an operating element receptacle (10) of the household appliance (1) controllable by the operating device (8) and is movable relative to the operating element receptacle (10) and removably positionable therefrom, and the operating element (9) comprises a light guide (22) which has a light coupling region (28) which is arranged further from a lateral edge of the operating element (9) than a light coupling region (29) of the light guide (22), characterized by that the operating device (8) has an infrared transmitting / receiving device (17) for selecting a functional sub-unit (3 to 7) of the household appliance (1), which is arranged with transmitting / receiving units (18) under the light guide (22) and is designed for detection through the light guide (22). [2] Operating device (8) according to claim 1, characterized bythat the operating element (9) has a base (24) through which the light guide (22), in particular the light coupling area (28), is covered from below. [3] Operating device (8) according to claim 1 or 2, characterized by that the operating element (9) has a base (24) which is permeable to light in the spectral range visible to humans and to the infrared range at least in the areas where the light can be coupled in for the light guide (22) and in the areas where the transmitting-receiving units (18) detect through the light guide (22). [4] Operating device (8) according to claim 2 or 3, characterized by that the base (24) is made of a plastic, in particular PSU or PESU. [5] Operating device (8) according to one of the preceding claims, characterized bythat the light guide (22) is designed as an annular disc-shaped body, on the outer edge of which an upwardly raised web (30) is designed as a light decoupling area (29). [6] Operating device (8) according to one of the preceding claims, characterized by that the operating element (9) has a casing wall (25) by which the light guide (22) is covered laterally and on which a cover (23) of the operating element (9) sits and / or the casing wall (25) is designed to be light-impermeable. [7] Operating device (8) according to claim 6, characterized by that the transmitting / receiving units (18) are each enclosed laterally to prevent scattered light. [8] Operating device (8) according to one of the preceding claims, characterized by that the operating element (9) has a cover (23) which is made of a glass, in particular chemically hardened glass. [9] Operating device (8) according to claim 8, characterized by that a film (35) or a print is applied to an underside (34) of the cover (23) facing the light guide (22), which film is permeable to infrared and light in the spectral range visible to humans. [10] Operating device (8) according to claim 8 or 9, characterized by that the cover (23) is designed to be light-impermeable in the areas which, when viewed in the direction of the longitudinal axis (A), are arranged above a light coupling area (28). [11] Operating device (8) according to one of the preceding claims, characterized by that light sources (14) are arranged in a straight line extension below a light coupling region (28) of the light guide (22) when viewed in the direction of the longitudinal axis (A). [12] Operating device (8) according to claim 11, characterized by that the light sources (14) are arranged in an annular channel whose walls (13, 15) are formed with heights which are greater than the light source heights. [13] Operating device (8) according to claim 12, characterized by that the walls (13, 15) are designed to be reflective on the inner sides facing the light sources (14), in particular a reflective film or a reflective coating is formed. [14] Operating device (8) according to one of the preceding claims, characterized by that light sources (14), the light of which is coupled into the light guide (22), are arranged around the holding magnet (12) in an annular channel directly adjoining a holding magnet (12) external to the operating element. [15] Household appliance, in particular a hob (1), with an operating device (8) according to one of the preceding claims.

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