EP2587166B1 - Cooking apparatus and method for visual display of a temperature on a cooking appliance - Google Patents

Description

Field of application and state of the art

The invention relates to a cooking device with optical temperature display and method for optical temperature display on a cooking device.

From the DE 102005025896 A1 It is known to provide a thermochromic paint on and / or under a cooktop panel. This is above a heater in the form of a radiant heater. In operation of the radiant heater, the thermochromic ink is heated, and at a choice of 40 ° C to 80 ° C for a color change or as a turnover temperature after switching off the radiant heater, the color change as long as the temperature of the cooktop plate and thus the thermochromic color about it lies. However, to do this, the cooktop panel itself is to be coated with the thermochromic paint.

From the DE 102005031392 A1 It is known to arrange a layer of thermochromic paint on the interior of a pot bottom. Thus, by a defined color change, a calibration to certain temperatures on the cooking vessel bottom can be made.

From the DE 102006011901 A1 it is known to provide thermochromic material as an indicator. However, here the thermochromic material is provided on a lamp under the hob plate, for example as a kind of coating over the lamp or as a coating on the glass bulb or lamp body. This lamp is located at a distance from the bottom of the hob plate.

From the JP 1047691 A , of the US 2004/112887 A1 and the DD 258511 A1 It is also known to provide thermochromic material on top of the top of a hob plate. Thus, a color change is optimally visible, just as a temperature indicator or as a warning.

Task and solution

The invention has for its object to provide a cooking device mentioned above and methods for displaying temperature on such a cooking device with which problems of the prior art can be achieved and in particular an advantageous way to display optical temperature or residual heat indicator on a cooking device, in particular on a Hob, can be created.

This object is achieved by a cooking device with the features of claim 1 and by a method having the features of claim 8. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features mentioned below are described only for the cooking device or only for the process. However, they should be able to apply independently for both the cooking device as well as for the process independently. The wording of the claims is incorporated herein by express reference.

It is envisaged that the cooking device comprises a hob plate with a heater underneath for heating a cooking vessel placed above it on the hob plate. Further, an optical display device for a temperature below the cooking plate and provided close to the heater. A distance may be in the range of a few cm, for example 1 cm to 5 cm, it being also possible that the display device is directly adjacent to the heater or even disposed therebetween and the hob plate. Furthermore, the display device has thermochromic ink or thermochromic material, which is provided for the hob plate or is visible through the hob plate.

According to the invention, the thermochromic ink or the thermochromic material is not directly or not permanently attached to the hob plate and not directly or not insoluble applied as a coating on this, but on a separate carrier. In this case, this carrier is applied or pressed with the thermochromic material against the underside of the hob plate, but the actual application of the thermochromic material takes place just on a separate carrier. There, the thermochromic material may also be applied insoluble. The thermochromic material, which is advantageously in powder form, can be mixed in a paint or in a coating, which in turn can then be applied or applied by a suitable method. The optical properties of the material or the coating after completion are largely determined by the admixed thermochromic material, so that in this regard, the color can be considered equated with the thermochromic material.

With the invention considerable effort can be saved in the manufacture of the display device and in particular during the coating step. Usually, such hob plates are in fact very large and thus not easy to handle in coating systems.

In a further embodiment of the invention, the thermochromic material may be such that it turns with a color change at a temperature increase over a Umschlagtemperatur of colored towards transparent or at least very bright or translucent and not strong or opaque changes. Thus, it is possible that certain display symbols under the thermochromic material are covered by it and are invisible, for example a warning of too high cooktop temperature. If this high temperature is above the aforementioned turnover temperature, the thermochromic material becomes transparent and the warning becomes visible. If the temperature drops again after a cooking process, when the temperature drops below the reversal temperature, a reverse color change takes place and the warning is again hidden. Alternatively, another color change can be used or achieved by a suitable choice of material, for example, from transparent or an inconspicuous, dark color to a conspicuous Color when exceeding a turnover temperature. Thus, a warning is visible as long as the temperature is above the Umschlagtemperatur, and disappears again when falling below.

In a further embodiment of the invention, it is possible that a plurality of layers of thermochromic material are provided one above the other. These can each have different Umschlagtemperaturen and should have at least partially different colors. Thus, at different Umschlagemperaturen a gradual optical temperature display can be created, which is not only a kind of Berührsicherung or Berührwarnung, but also can display more information about the temperature. Furthermore, an even stronger visual effect can be achieved as a display by means of different colors, so that, for example, multi-colored warnings of thermochromic materials become visible.

In an alternative embodiment of the invention, it is possible to provide several layers of at least one thermochromic material and at least one non-thermochromic material one above the other. Advantageously, the thermochromic material covers or covers the other layer.

An advantageous conversion temperature may be about 50 ° C to 90 ° C. In any case, the turnover temperature should be selected so that the color change takes place at temperatures on the top of the cooktop panel in the range of 50 ° C to 70 ° C, which are considered as usual values or limit temperature for a hot indication or residual heat indicator, since from these temperatures and above it a risk of burns when touching the hob plate called limit temperature can be selected for the touch safety. If some space is provided, then it can be assumed that there is a significant temperature gradient of more than 10 ° C or even more than 20 ° C and the limit temperature at the top of the hob then about 70 ° C to 90 ° C on the display device for the Color change as turnover temperature corresponds.

In the invention, the thermochromic material is applied to an electrical insulator. This should be advantageous over a large area and the insulator can then be arranged approximately parallel to the hob plate. On the one hand, it is possible to arrange it laterally next to a heating device, which means good visibility of the temperature indicator even when the cooking vessel is set up. When using a radiant heater as a heater, this is recommended, since an arrangement of the temperature display or the thermochromic material would adversely affect both its heating effect and would most likely lead to damage or destruction.

More advantageous than in a radiant heater, the invention is realized with a so-called holding heater, which acts as a contact heater and has electrical resistance heating elements and is applied to the underside of the hob plate. Such holding heater or their electrical resistance heating achieve by far not as high temperatures as radiant heaters. Thermochromic material can then be applied to its upper side, which may be a cover or a support for the resistance heating element, towards the hob plate, as otherwise described, for example as a direct coating or as a sticker. The support for the resistance heating element may be ceramic, for example alumina or the like, or consist of metal with an insulating layer. or as a sticker. The support for the resistance heating element may be ceramic, for example alumina or the like, or consist of metal with an insulating layer.

In a further alternative embodiment of the invention, the heating device is an induction heater with an induction coil, as used in cooktops, and then an arrangement of the temperature display is also possible directly above the heater. Such induction coils are usually disc-like, so that the arrangement of the temperature display is well possible. Finally, this has the advantage that usually a residual heat indicator is only needed when the cooking vessel has been removed, and in this case, a display located above the heater is basically visible. Furthermore, even with an induction heating device, a temperature display is advantageously large-area, so that it is clearly visible. Advantageously, it is thus possible to arrange the temperature display between the aforementioned induction heater and the hob plate.

In the event that the heating device is a holding heater or Kontaktheizkörper or an induction heater and having an overlying insulator disc, which may consist of micanite or ceramic, the top or this insulator disc can serve as a carrier for the thermochromic material of the temperature display. The thermochromic material is thus applied to an already existing component in the form of the insulator disk, for example by a conventional and suitable for a color and the insulator disk method. In this case, the thermochromic material to the hob plate and can be particularly advantageous even pressed against this. This has on the one hand the aforementioned advantage of better temperature coupling and avoids the above-described features of the cost of coating the hob plate itself with the thermochromic material. It is possible, for example, as described above, that the thermochromic material has a color change from colored to transparent when a reversal temperature is exceeded, wherein a warning due to overheating is visible through the transparent thermochromic material.

It is possible that the insulator disk has a strong color, for example red. In addition, a thermochromic material may be applied, preferably with a prescribed dark color, which may be, for example, blue, black or green. In the above-described color change from colored to transparent when exceeding a Umschlagtemperatur the thermochromic material disappears, so to speak, through the cooking plate through not visible dark thermochromic color and the strong color of the insulator disc is visible as an optical temperature display and especially as a warning. This type of exploitation of the color change of the thermochromic material such that it is present as a color below the turnover temperature itself, but because of the dark color design virtually invisible and yet opaque, and becomes invisible only after exceeding the Umschlagtemperatur, has the advantage that it is better for thermochromic material with a dark color to cover an underlying, conspicuous, normal color, which is then ultimately very visible, rather than providing a reversed thermochromic color even with appropriate luminosity or visibility. Thus, a thermochromic material with a dark hue can almost better hide a striking hue and then make it visible than it itself by means of a thermochromic material represent.

In general, mixtures of colors and combinations of thermochromic and non-thermochromic colors or materials are possible. One manufacturer is the company TMC Ltd. from UK with a CHROMAZONE pigment, see also the alternative EP 1888004 B1 , As a possible example, a sticker or adhesive film may be provided on the one hand with the strong color and on the other hand with the thermochromic material over it. Alternatively, the sticker itself can be kept in the strong color. Such a sticker or such a film can be applied or glued on top of the induction heater, in particular on an aforementioned insulator disk. Thus, it is possible that a standard induction heater can be provided later with a thermochromic sticker and thus only minimal constructive change or additional expense incurred. A film for the adhesive film or the label with appropriate temperature resistance for use directly on induction heating is also known in the art, for example as a Kapton film.

In a further embodiment of the invention, it is possible that the cooktop panel is not only translucent, so that a color must be quite strong or glaring to be perceived through them, but even almost or completely transparent. Such cooktop panels are also made of glass ceramic, such as Eurokera or Schott. Then signal colors directly from thermochromic color are also well usable and well visible through the hob plate for a very versatile temperature display, which also has many possibilities in the optical design.

In general, not only a colored surface can be displayed as a temperature display, but various symbols, words or even company logos or the like.

The application of the thermochromic material to a support can be effected, for example, by dyeing an aforementioned insulator disk by a dipping process, detached from the respective material. Likewise, a correspondingly colored ceramic as aforementioned insulator disc can be used, which is so colored with thermochromic material. Finally, it is also possible to use colored stickers which are either provided with a thermochromic material as a coating on a corresponding film layer or which have a film which has been dyed correspondingly with thermochromic material. Further possibilities for application are spraying and printing processes, in particular screen printing and pad printing.

For the method of displaying the temperature on a cooking device described above, according to a first possibility, it may be provided that the thermochromic material of the display is heated directly by the heating device, so that it passes through the turnover temperature. Then either the thermochromic material itself serves as a temperature indicator directly or, as it were, releases an underlying, more noticeable color as a temperature indicator.

Alternatively, in one of these methods, a thermochromic material may be indirectly heated, via the cooktop panel itself heated by the heater. This has the advantage that a temperature of changeover for the thermochromic material will be closer to the limit temperature prevailing for contacting the surface of the cooktop panel can. This also requires a less temperature-resistant thermochromic material. The latter method can be used in particular together with induction heaters, while the aforementioned method is more suitable for radiant heaters or for the holding heater or contact heater.

These and other features are apparent from the claims and from the description and drawings, wherein the individual features in each case alone or in the form of sub-combinations be realized in other areas. However, the scope of protection is defined by claims 1-8.

Brief description of the drawings

Fig. 1

eine seitliche Schnittdarstellung durch eine erste erfindungsgemäße Kochvorrichtung mit einer ringförmigen optischen Anzeigevorrichtung mit thermochromem Material um die Heizeinrichtung herum,

Fig. 2

eine zweite erfindungsgemäße Kochvorrichtung mit einer Induktionsspule als Heizeinrichtung und einer flächig darauf aufgeklebten optischen Anzeigevorrichtung,

Fig. 3

eine im heißen Zustand der Kochfeldplatte bzw. der optischen Anzeigevorrichtung entsprechend Fig. 2 darunter dargestellten Anzeige,

Fig.4

eine starke vergrößerte Schnittdarstellung durch die Anzeigevorrichtung gemäß Fig. 2,

Fig. 5

eine erweiterte zweistufige Anzeige aufbauend auf Fig. 3,

Fig. 6

eine nochmals erweiterte Anzeige ähnlich Fig. 3 und

Fig. 7

eine weitere Anzeige.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

Fig. 1

3 a side sectional view through a first cooking device according to the invention with an annular optical display device with thermochromic material around the heating device,

Fig. 2

a second cooking device according to the invention with an induction coil as a heating device and a surface-mounted thereon optical display device,

Fig. 3

one in the hot state of the hob plate or the optical display device accordingly Fig. 2 display shown below,

Figure 4

a strong enlarged sectional view through the display device according to Fig. 2 .

Fig. 5

an advanced two-tier ad based on Fig. 3 .

Fig. 6

an enlarged display similar Fig. 3 and

Fig. 7

another ad.

Detailed description of the embodiments

In Fig. 1 is a cooking device in the form of a hob 11 shown in lateral section with hob plate 13, under which a heater 18 is arranged. The hob plate 13 may be a usual glass ceramic hob plate with bottom 14 and top 15. It can be colored, for example, colored red-brown. Alternatively, the hob plate 13 may also be colored milky white. Advantageously, it is substantially transparent or transparent, at least above the display device or the thermochromic material. So it is particularly easy to recognize. Around transparent areas, the hob plate can be colored or coated with paint or provided as a kind of masking known per se. This can also be provided on a separate cover under the hob plate.

In principle, the heating device 18 can be a radiant heater used for cooktops 11 or a heat-retaining radiator or contact radiator on the one hand or an induction coil for induction heating on the other hand. In the present case, this plays for the embodiment of Fig.1 only for the expected or to be set temperatures a role.

The heater 18 is advantageously pressed from below to the bottom 14 of the hob plate 13, although not directly attached thereto. However, a defined position can be achieved in this way.

Around the heater 18, a display device 20 is arranged in a ring shape. It runs relatively close to the heating device 18 and can either have a small distance from the underside 14 of the hob plate 13 or rest or be pressed against it. An actual attachment of the display device 20, however, via separate fastening means. On the one hand, here, as in Fig. 1 is shown on the left, a retaining projection 22 may be provided, on which the display device 20 is mounted, for example glued or clamped. The retaining projection 22 may be provided on the side of the heating device 18 or protrude from this, For example, as a sheet metal tab or the like. be bent out. Alternatively, it may be clamped on it as a circumferential ring or the like.

An alternative embodiment of a holding projection 22 'is in Fig.1 shown on the right. This retaining projection 22 'is not provided directly on the heater 18, but either on a separate holding device, which possibly also holds the heater 18 and other heaters of the hob. Alternatively, the retaining projection 22 'may also be permanently glued to the underside 14 of the hob plate 13 and then, for example, by clamping or snapping, the display device 20 hold. Important here is just the one the arrangement of the display device 20 around the heater 18 and very close to it. On the other hand, the display device 20 may indeed be pressed against the underside 14 of the hob plate 13, this may even be advantageous. In any case, the display device 20 is not permanently attached to the hob plate 13, so not by, for example, gluing or direct coating. In this way, with the invention, the structure or the production of the hob plate 13 can be kept simpler.

In the operation of the heating device 8 is to distinguish between a radiant heater or a holding heater or contact heater on the one hand and an induction coil on the other. In the case of a radiant heater, this radiates, for example, with glowing heating elements in the manner of spirals or the like., Up through the cooktops 13 with their heating power, which is then coupled via an underside of a raised pot in this or in the food therein. In this case, the hob plate 13 is heated directly by the radiation power and indirectly on the bottom of the pot. This then leads to the end of the cooking process to the problem with the high temperature of the hob plates 13 and its top 15 in this area, which is why a hot display or Residual heat indicator is necessary to protect an operator from accidental contact. Similarly, it is in the holding heater or contact heater, the hob plate 13 even only directly heated by it rests against her. The heated hob plate 13 in turn radiates down to the display device 20 or gives their heat on and then there at a certain envelope temperature cause the color change mentioned above.

Assuming an aforementioned critical temperature of 50 ° C to 70 ° C for the cooktop from above a residual heat indicator should be activated, it can be chosen even lower, given the heat transfer from the cooktop plate 13 to the display device 20 this Umschlagtemperatur. In operation of the heater 18 in the form of a radiant heater, although the display device 20 is heated to a considerably higher temperature, in practice at 150 ° C to 250 ° C. But this does not bother, because then the Umschlag temperature is exceeded and the color change takes place on the thermochromic material. Essentially, this is also about the falling below the Umschlagtemperatur with the result that then a visual display disappears again or they should just until reaching the Umschlagtemperatur, ie at higher temperatures, should be present. Therefore, for example, a Umschlagtemperatur of 35 ° C to 60 ° C be sufficient, especially in the case that the display device 20 is applied directly to the bottom 14 of the hob plate 13 and thus a very good heat transfer is given with very similar temperatures. Of course, when selecting the temperature of the turnover of the thermochromic material, it must also be taken into consideration that in the central area above the heating device 18, the cooktop panel 13 is very likely to be even warmer than in the peripheral areas near the display device 20.

The display device 20 consists of a carrier 23, for example made of temperature-resistant plastic or other materials such as micanite or ceramic. Applied to it is thermochromic material 24 as a color or as a coating. Depending on the chosen mechanism described above, at a temperature on the display device 20 above the temperature of change for the thermochromic material 24, either this itself can turn from an unobtrusive color, such as a dark color such as blue, to a conspicuous side such as red, which will serves as an indicator or residual heat indicator. Thus, the color change at temperatures above the Umschlagtemperatur the optical residual heat indicator is formed by the folded thermochromic material itself.

Alternatively, a strong and eye-catching color, for example red, may be provided on the upper side of the support 23, which is covered by the thermochromic material 24 as a color with a dark hue below the turnover temperature. Above the turnover temperature, this thermochromic material 24 is then substantially or completely transparent so that the previously masked and invisible display color becomes visible and serves as an optical residual heat indicator.

In the case of an induction heater as a heater 18, this can heat the display device 20 only to a small extent directly, for example due to coil losses. An inductive heating of a correspondingly heatable support 23 of the display device 20 is to be rejected, in particular also because it is then in turn independent of the temperature of the hob plate 13 itself. In this case, in this case, the display device 20 with the thermochromic material 24 only, as previously described actually, heated by the heat recovery of the cooktop plate 13 itself. In this case, the induction heater does not heat the hob plate 13 directly, it is only by the heat of the directly heated bottom of the pot warm and thus less strong or less quickly. An alternative embodiment of a hob 111 according to Fig. 2 has a heating device 118 as an induction heater. This induction heating device 118 is provided on its upper side with a display device 120 and pressed with this on an underside 114 of a hob plate 113. A pressing of the induction heating 118 can be done in a conventional manner, for example by them and other induction heaters of the hob 111 is mounted on a conventional, not shown support plate and this in turn mounted on outside edge mounted brackets on the hob plate 113. As an alternative to an induction heating device, it may also generally be an aforementioned holding heater or contact heater, which is also usually pressed against the underside of the hob 111. It may comprise a support on which, possibly with an insulating layer between them in a metallic support made of sheet metal or the like., An electrical resistance heating element is provided, wherein the carrier in Fig. 4 is above and pressed directly to the bottom 114 of the hob 111 for heat transfer. A display device 120 would then be arranged on the upper side of the carrier, while the resistance heating element is provided on its underside.

The large-area display device 120 on the top of the induction heater 118 is thus pressed directly to the bottom 114 of the hob plate 113, but again not directly attached thereto or glued or otherwise releasably secured. The exact structure of the display device 120 is off Fig. 4 to see. A carrier film 123 has on its underside an adhesive layer 126, by means of which it is adhesively bonded to the upper side of the induction heater 118. The backing film 123 may be, for example, a so-called Kapton film or any other insulating or insulating, as they usually on the tops of Induction heaters are placed to press against the underside of hob plates.

On top of the carrier film 123 is a color layer 128, for example, a previously described strong color, preferably in red. It can either be provided over a large area, substantially as large as the display device 120, or else only have a symbol shape, for example the letters according to FIG Fig. 3 "HOT".

The color layer 128, in turn, is covered by the thermochromic material 124, which in this case has such properties that it is dark below a turnup temperature, for example, dark blue or dark green, and thus the color layer 128 can not be seen through the cooktop plate 113 as such. Above the turnover temperature, the thermochromic ink 124 then becomes substantially transparent, so that the ink layer 128, possibly in the form of the symbol or the font according to FIG Fig. 3 , becomes visible and serves as a residual heat indicator.

The advantage of the arrangement according to Fig. 2 The display device 120 directly on top of the heating device 118 is that usually such induction heating with induction coils anyway have an insulating film on the top, for example, an aforementioned Kapton film, alternatively an insulating. So no other components are needed, but just something different trained. These then have in the example of the insulating film or insulating on a print or a sticker, depending on the customer and application or series.

Another advantage is that then a large-area residual heat display can be achieved, which with the annular design in the Fig. 1 less possible.

Finally, it can be assumed that the maximum residual heat at the hob plate 113 is present in the central region in the middle above the heating device, and thus an optical residual heat indicator should also take this into consideration. On the one hand, this can be done by per se known temperature profiles both in terms of time and in terms of space from this central region to the outer edge region over the outer edge of the heater 118. Nevertheless, a residual heat indicator directly detecting this middle area is more accurate. This also speaks in favor of this embodiment.

As an alternative to the specific embodiment of the display device 120 with ink layer 128 and thermochromic material 124 or corresponding color or coating over it, two thermochromic colors can be provided with different Umschlagtemperaturen. One of them has its color change at a higher temperature, for example, corresponding to a temperature at the top of the hob plate of well over 100 ° C, so if a touch is still very dangerous. The other color change can be made at a temperature which corresponds to a temperature at the cooktop panel of about 50 ° C to 70 ° C, ie the usual value for residual heat indicators, below which a touch of the cooktop panel no longer means the risk of burns. These two thermochromic materials may then either be provided directly one above the other and undergo their color change one by one to indicate different underlying symbols. Alternatively, they may be provided side by side over a bold color. Under the thermochromic material with the lower turnover temperature, a coating of strong color could be used accordingly Fig. 3 be provided with "HOT". Under the thermochromic material with the high turnover temperature, it could be in strong color according to "VERY". If the hotplate is very hot, then "VERYHOT" will be displayed by the display device 120 as shown in FIG Fig. 5 shows, and at slightly lower temperatures, but still above the threshold temperature of 50 ° C to 70 ° C, only "HOT" accordingly Fig. 3 ,

Fig. 6 shows that instead of writing a logo can be displayed. In Fig. 6 above is shown in the cold state, as the thermochromic layer has a certain hue, such as blue. In the heated above the limit temperature of 50 ° C to 70 ° C state, the color changes in the representation below and is white, for example. This can be used both as a temperature display for warning purposes as well as a temperature-dependent operation indicator, so that when warmed up the logo appears, for example, the device manufacturer.

In the Fig. 7 is shown as in a previously described two-layer structure of the colors in the cold state in the upper display only a circle can be seen. When heated below, for example above a limit temperature of 70 ° C, the illustration below can be seen with the number "70".

Here, the number "70" in a color on a support or the like. applied, for example in red. This can be a normal temperature resistant paint. It is completely covered by a thermochromic material or a paint or coating, which has a dark color shade when cold up, for example blue as described above. Exceeding the stated limit temperature of 70 ° C for the thermochromic material this has its color change, for example, too transparent or white, so that the number "70" of the lower color can shine through and becomes visible.

Claims (8)

1. Cooking appliance (11, 111) having an optical temperature indicator, wherein said cooking appliance includes a cooktop plate (13, 113) having a heating device (18, 118) arranged underneath for heating a cooking vessel being positioned above on said cooktop plate, wherein an optical indicator device (20, 120) for temperature is provided below said cooktop plate and close to the heating device (18, 118), wherein said indicator device includes thermochrome material (24, 124) towards the cooktop plate (13, 113), wherein said thermochrome material (24, 124) is applied on an electric insulator, which is a separate carrier (23, 123), characterized in that the separate carrier with the thermochrome material is detachably placed or pressed against the bottom side (14, 114) of the cooktop plate (13, 113).
2. Cooking appliance according to claim 1, characterized in that said thermochrome material (24, 124) exhibits a color change upon a temperature increase above a changeover temperature from coloured to transparent.
3. Cooking appliance according to claim 1 or 2, characterized in that a plurality of superimposed layers of thermochrome material (24, 124) are provided, said layers preferably having different changeover temperatures and/or different shades of colour.
4. Cooking appliance according to any of the preceding claims, characterized in that a plurality of superimposed layers of thermochrome material (124) and of non-thermochrome material (128) are provided.
5. Cooking appliance according to any of the preceding claims, characterized in that the changeover temperature is in a range of approximately 50 °C to 90 °C.
6. Cooking appliance according to any of the preceding claims, characterized in that said thermochrome material (24, 124) is applied to the electric insulator as a carrier (23, 123) on a large area and in parallel to the cooktop plate (13, 113), in particular laterally adjacent to a heating device (18, 118).
7. Cooking appliance according to any of the preceding claims, characterized in that said cooktop plate (13) is transparent, in particular is made of transparent glass ceramics.
8. Method for visual temperature display on a cooking appliance (11, 111) according to any of claims 1 to 7, characterized in that said thermochrome material (24, 124) is heated indirectly by means of the cooktop plate (13, 113) heated up by the heating device (18, 118), wherein then the cooktop plate in turn heats up the temperature indicator including the thermochrome material (24, 124) to exceed the changeover temperature thereof for visual temperature display.

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