BE1030254A1 - Cooking appliance with a cooking chamber and at least one viewing window - Google Patents

Abstract

The present invention relates to a cooking appliance (1) with a housing and a cooking chamber (3) arranged in the housing, the cooking chamber (3) being delimited by cooking chamber walls (4.1, 4.2, 4.3, 4.4), with the A camera (15) for observing the cooking chamber (3) is arranged in the cooking chamber (3), with a first viewing window (9.1, 9.2) in a first region of the cooking chamber walls (4.1, 4.2, 4.3, 4.4), in particular between the camera (15 ) and the cooking chamber (3), wherein the first viewing window (9.1, 9.2) is formed by a transparent substrate (20) and a hydrophilic ceramic layer (21) applied to the substrate (20) on the cooking chamber side, the ceramic layer (21 ) is formed in a transparent layer thickness (d), and wherein the ceramic layer (21) has in particular a lipophobic property. The invention also relates to a viewing window (9.1, 9.2) for such a cooking appliance (1).

Description

1 BE2022/5079

Cooking appliance with a cooking space and at least one viewing window

Technical area

The present invention relates to a cooking appliance with a housing and a cooking space arranged in the housing, the cooking space being through

Cooking chamber walls are limited, and in a first area the

A first viewing window is embedded in the cooking chamber walls. In particular, a camera for observing the cooking space is arranged in the housing outside the cooking space, the first viewing window being embedded in a first area of the cooking space walls between the camera and the cooking space. Such a cooking appliance is preferred as a steamer or oven with one

Steam cooking function trained. The invention further relates to a viewing window for such a cooking appliance.

Background of the invention

Cooking appliances such as ovens in which the cooking chamber walls

Viewing windows are already known. On the one hand, it is well known that such cooking appliances have viewing windows in a mostly vertical position

Front, especially in a cooking chamber door, are provided through which one

The person using the cooking appliance can see through it, for example around the

Observe or check the cooking process of a food. It is also known that viewing windows are arranged in the cooking chamber walls between the cooking chamber and a camera, for example in a horizontal cooking chamber wall that delimits the cooking chamber at the top. Such a camera serves, for example, as a sensor for controlling the cooking device, such as an automatic switch-off depending on the degree of doneness of a food to be cooked or an automatic browning of the food to be cooked and/or allows a person using it to observe the cooking chamber from a distance via a terminal device.

2 BE2022/5079

The problem with the aforementioned cooking appliances is that during a...

During the cooking process, the vapors in the cooking chamber condense out on the viewing windows and form a fog there, so that the view through the

Viewing window for a person using it and/or a camera is degraded or prevented entirely. The vapor usually consists of:

Essentially from air, water vapor and fats dissolved in the food being cooked

Oil. In particular, the problem mentioned exists with cooking appliances with a

Steam cooking function, in which the vapors are particularly high

Has moisture content. There is also the problem with viewing windows on a vertical cooking chamber door that excessive fogging occurs

Drops form that run down the viewing window and a lower one

The edge of the cooking compartment door can allow steam to escape to the outside of the cooking appliance due to non-liquid-tight seals. This problem exists particularly in pyrolysis-capable cooking appliances, in which the selection of sealing materials is limited due to the high temperatures of up to 500 ° C that occur during pyrolysis and a liquid seal is not possible or only possible with uneconomical design effort.

From WO 2017/013011 A1 it is for household appliances such as dishwashers,

Washing machines or dryers are known to reduce condensation on walls of closed interior spaces using a superhydrophilic PDA coating.

From US 2018/0073741 A1 an oven is known in which

Cooking chamber walls have a coating with hydrophilic and/or lipophilic

Properties are applied to remove impurities in the area

Coatings accumulate and reduce in other areas of the oven. Cleaning the oven can then focus on the areas of the

Coatings can be reduced.

3 BE2022/5079

Description of the invention

Based on the background of the invention, it is an object of the present invention to provide an improved cooking appliance

Ensure visibility through a viewing window.

The object of the invention is achieved by the features of the independent

Main claims resolved. Advantageous refinements are in the

Subclaims specified. If technically possible, the teachings of the

Subclaims can be combined as desired with the teachings of the main and subclaims.

In particular, the task is solved by a cooking appliance with a

Housing and a cooking space arranged in the housing, the

Cooking space is delimited by cooking space walls, with a first viewing window being embedded in a first area of the cooking space walls, the first

Viewing window is formed by a transparent substrate and a hydrophilic ceramic layer applied to the substrate on the cooking chamber side, the

Ceramic layer is formed in a transparent layer thickness, and wherein the ceramic layer has a lipophobic property.

Advantageous aspects of the claimed invention are explained below and preferred modified embodiments of the invention are explained below

Invention described. Explanations, especially regarding advantages and

Definitions of characteristics are essentially descriptive and preferred, but not limiting, examples. If an explanation is limiting, this will be expressly mentioned.

As far as elements are designated using a number, for example “first component”, “second component” and “third component”, this is the case

Numbering is intended purely for differentiation in the designation and does not represent a dependency of the elements on each other or a mandatory one

Sequence of the elements. This means in particular that a device does not have to have a “first component” in order to have a “second component”.

4 BE2022/5079 can. The device can also have a “first component” and a “third

Component” include, but without necessarily having a “second component”.

There can also be multiple units of a single element

Numbering must be provided, for example several “first components”.

A cooking appliance is designed in particular as an oven, in which the

Preparation of a food, for example, temperatures of around 100-250 ° C are provided in the cooking space. Such an oven also particularly preferably has a steam cooking function, in which the steam opens into the cooking space

Steam openings allow water vapor to be led into the cooking chamber

Cook food in an environment saturated with water. The cooking appliance also preferably has a pyrolysis function, in which the temperature in the

Cooking chamber can be increased to up to 500°C, so that

Organic contaminants located on the cooking chamber walls are decomposed and released from the cooking chamber walls. Organic contamination occurs when cooking food, particularly through fats and oils that come off the food and settle on the walls of the cooking chamber. The cooking appliance can also be designed with an integrated microwave.

The cooking space of the cooking appliance is preferably as a cavity insulated from an outer wall of the cooking appliance by means of thermal insulation

Housing formed. The cooking space can preferably have an opening

Food can be filled with food or such food can be removed via the opening

removed from the cooking space. In or on the cooking space there are preferably means for heating the air in the cooking space and means for

Circulation of the air in the cooking space is provided. In particular, there are also air lines and/or in the cooking space or in the cooking space walls

Air baffles are provided, the geometry of which influences the air flow in the oven. The term air is also used here in the sense of vapor and vice versa, with air containing more or less substances dissolved in it and/or depending on the operating state and time of operation in the cooking chamber

Steam components are present. For example, something in the cooking space emits

Substances and steam corresponding to the food being cooked into the air, but only when a

The cooking process begins after heating up. You can also use it in the cooking space

Means for radiating heat may be provided.

A viewing window is at least vapor-tightly sealed, in particular with respect to the cooking chamber wall in which it is embedded and/or with respect to other cooking chamber walls to which it 5 adjoins. There can then be no steam on it

Viewing window, for example to the components of the device arranged behind it

cooking device or in the area surrounding the cooking device. The viewing window is particularly preferably sealed in a liquid-tight manner. For liquid tightness

However, depending on the maximum temperature in the cooking chamber, only a limited selection of sealants is available. For example, a silicone with good sealing properties cannot be used in cooking appliances with a pyrolysis function, or can only be used with great design effort, since it would be damaged by the temperatures used for pyrolysis. In pyrolysis-capable cooking appliances, non-liquid-tight glass fiber seals are used, which meet the high requirements

Can withstand temperatures, but not sufficiently

Seal liquid.

The above solution to the problem now includes the teaching that the first

Viewing window has a hydrophilic ceramic layer. Through such a layer, water that precipitates on the first viewing window forms a particularly small contact angle with the first viewing window. The water does not form drops on the first viewing window, which would strongly refract the light falling through the viewing window and thus act as a fog obstructing the view, but rather a layer of water which forms an almost parallel surface to the surface of the first viewing window. Due to these almost parallel surfaces, light falling through the first viewing window is refracted significantly less than by fine drops in the usual fogging. The ceramic layer is formed with a transparent layer thickness and therefore, particularly advantageously, has no relevant influence on the view through the first viewing window.

Such a transparent layer thickness can vary depending on the ceramic layer

6 BE2022/5079 material or materials used can be selected. One

A layer thickness at which the layer produces a sufficient hydrophilic effect and at the same time remains transparent can be achieved particularly advantageously with ceramic oxide. In particular, a ceramic oxide also has sufficient

Temperature resistance for the present application in a cooking appliance, in particular for the temperatures prevailing in the cooking space during pyrolysis cleaning.

Furthermore, the solution described above includes the teaching that

Ceramic layer has a lipophobic property. The ceramic layer therefore forms a large contact angle with oils and/or fats, so that such

Substances cannot fall on the first viewing window. This advantageously ensures that there are no organic substances on the viewing window

Deposit contaminants that would impair the view through the viewing window. The first viewing window thus remains free of dirt and fog, so that overall there is a significantly improved view through it

Viewing window is possible.

A lipophobic property of the ceramic layer can be achieved, for example, by combining different ceramics in the ceramic layer and in this way forming a combined layer. Ceramic particles can also be embedded in another material or materials, for example in a matrix made of another material or materials, whereby a combined layer is also created.

Furthermore, a lipophobic property can also be achieved, for example, through additional structuring or chemical treatment of the surfaces

Ceramic layer can be achieved.

In one embodiment, the cooking appliance has an opening for filling the

Cooking space and at least one cooking space door for closing the opening, the cooking space door forming a cooking space wall and the first viewing window being embedded in the cooking space door. The first viewing window serves in particular for a person standing in front of the cooking appliance to observe the cooking space,

7 BE2022/5079 for checking the doneness of the food being cooked. Furthermore, a camera for observing the cooking chamber can also be arranged in front of a first viewing window embedded in the cooking chamber door and outside the housing, for example for controlling the cooking appliance and/or for observing the cooking chamber from the

Distance via a device. Through the above-described training of the first

Viewing window with a ceramic layer then has the advantage that the person standing in front of the cooking appliance or the camera positioned in front of the first viewing window have the clearest possible view of the cooking space or the food to be cooked therein at all times, with the first viewing window being free of

Mist and/or dirt remains.

In an embodiment in which the cooking chamber door, and correspondingly also the first viewing window, extend in a vertical plane, the above-described hydrophilic ceramic oxide coating further achieves the advantage that no drops form on the first viewing window and run down the first viewing window and meet a seal at a lower end. Instead, a layer of water forms on the first viewing window, which has a more favorable surface area ratio than the drops

Has volume and thus promotes rapid mass transport of the liquid back into the vapor phase. In this respect, there is no need for a liquid-tight seal from the environment in the lower region of the first viewing window in order to prevent liquid from escaping from the cooking appliance. Seals that are suitable for higher temperatures, but only vapor-tight, can therefore be used.

The task is also solved by a cooking appliance with a housing and a cooking space arranged in the housing, the cooking space being through

Cooking chamber walls are limited, being in the housing outside the

A camera for observing the cooking chamber is arranged in the cooking chamber, a first viewing window being embedded between the camera and the cooking chamber in a first area of the cooking chamber walls, the first viewing window being formed through a transparent substrate and on the substrate on the cooking chamber side

8 BE2022/5079 applied hydrophilic ceramic layer is formed, and wherein the

Ceramic layer is formed in a transparent layer thickness.

Such a cooking appliance has the advantages already described with regard to the relevant features. In particular, the cooking device for a camera located inside the housing has the advantage that water deposited on the first viewing window forms a small contact angle and thus creates a thin layer of water, which produces less light refraction than would otherwise form water drops. The water does not form any fog on the first viewing window, as already described with regard to the first solution, and the view through the first viewing window is not blocked or prevented by such fog. The camera is preferably arranged above the cooking space, with the first viewing window being embedded in a cooking space wall that delimits the cooking space at the top and extending in a horizontal plane. By avoiding

Misting on the first viewing window, i.e. the formation of fine droplets, is advantageously avoided, such droplets detaching from the surface of the first viewing window and dripping onto the food to be cooked.

In one embodiment, the ceramic layer of the first viewing window also has a previously described lipophobic property, so that no dirt can be deposited on the first viewing window.

In a preferred embodiment of one of the solutions described above

The object of the cooking appliance is to have a second viewing window embedded in a second area of the cooking chamber walls, the second viewing window being formed by a transparent substrate and a hydrophilic ceramic layer applied to the substrate on the cooking chamber side, and wherein the ceramic layer is formed in a transparent layer thickness. The second viewing window then also has the above-described advantageous properties when water deposits and remains free of fog.

In one embodiment of this embodiment with at least one camera arranged outside the cooking space for observing the cooking space, one

9 BE2022/5079

Opening for filling the cooking space and at least one cooking space door

Closing the opening, with the cooking chamber door forming a cooking chamber wall, is the first viewing window between the camera and the cooking chamber in one

The cooking chamber wall is recessed and the second viewing window is recessed in the cooking chamber door. An improved view is achieved both for the viewing window in the door and for the viewing window through which the camera observes the cooking space or the food being cooked.

In a preferred embodiment, the ceramic layer of the second viewing window also has a previously described lipophobic property, so that no contamination can accumulate on the second viewing window.

In an embodiment of one of the solutions described above, in which the

Cooking appliance has a cooking compartment door, the cooking appliance has a door seal

Sealing the opening closed by the cooking chamber door against one

Surroundings of the cooking appliance, with the door seal in particular

Glass fiber is formed. Such a seal prevents leakage

Steam and/or liquid from the cooking space into the environment

Avoid placing the cooking appliance on the door. A door seal made of glass silk also has the advantage that it can withstand high temperatures in the cooking chamber, such as those that occur during pyrolysis cleaning, without

show any damage or leaks.

In a further embodiment of one of the aforementioned solutions is the

Ceramic layer of the first viewing window and / or the second viewing window as

Ceramic oxide layer, for example with silicon nitride, titanium dioxide and/or

Aluminum oxide formed. These ceramic oxides can advantageously achieve favorable hydrophilic properties with layer thicknesses that are transparent and temperature-resistant, even at the temperatures required for pyrolysis cleaning, and have a good longevity. The hydrophilic properties can therefore be achieved with the materials mentioned even with such thin layer thicknesses that the ceramic oxide layer can be applied to the substrate sufficiently thinly to be transparent. The ceramic oxide layer can

10 BE2022/5079 also have a plurality of materials, in particular in order to develop a lipophobic property in addition to a hydrophilic property. For this purpose, for example, the ceramic oxide is embedded in another material.

In another embodiment, one of the aforementioned solutions is

Ceramic layer of the first viewing window and / or the second viewing window as

Non-oxide ceramic layer, for example with silicon carbide, silicon nitride,

Titanium nitride formed.

In one embodiment, the layer thickness of the ceramic layer is the first

Viewing window and/or the second viewing window between 50 nanometers and 1500 nanometers. With such a layer thickness is depending on the

Ceramic layer used material or materials used, a sufficient hydrophilic effect to avoid fogging on the

Viewing window and to achieve, whereby the ceramic layer is transparent. A lipophobic property can also be developed favorably with such a layer thickness. Preferably, the layer thickness is as thick as possible when existing

Transparency was chosen to make the ceramic layer as durable as possible.

In a further embodiment, the ceramic layer forms the first

Viewing window and/or the second viewing window with water

Contact angle less than 15°. Particularly preferably, the ceramic layer of the first viewing window and/or the second viewing window forms one with water

Contact angle less than 12°. With such a contact angle, a sufficiently low degree of light refraction is achieved in a viewing window wetted with water, so that the view through the window is not obstructed or only to an acceptable extent by the water layer.

In another preferred embodiment, the ceramic layer is the first

Viewing window and / or the second viewing window are applied by a sol-gel process, a PVD process, a CVD process and / or a PECVD process. In a sol-gel process, the ceramic layer is made from colloidal dispersions. PVD stands for “physical vapor deposition” and describes a vacuum-based process in which the material is used for the

11 BE2022/5079

Ceramic layer is transferred into the gas phase and condensed out on the substrate to form the ceramic layer. CVD stands for “chemical vapor deposition” and describes a process in which a heated

Surface of the substrate the ceramic layer as a result of a chemical

Reaction is separated from the gas phase. A PECVD corresponds to a CVD process, whereby the preceding PE stands for “plasma enhanced” and indicates that in such a CVD process the chemical reaction is enhanced by a plasma.

In one embodiment, at least one of the first viewing window and the second viewing window has a structuring of the surface on the cooking chamber side. By means of such structuring, a hydrophilic and/or lipophobic property of the ceramic can be further improved. For example, the contact angle that water occupies on the surface can be reduced, or the contact angle that a fat or oil occupies on the surface can be increased. The surface is structured, for example, using a laser-based process or a chemical process.

The object is also achieved by a viewing window for a cooking appliance described above, comprising a transparent substrate and a hydrophilic ceramic layer applied to the substrate, the ceramic layer being formed in a transparent layer thickness and the ceramic layer having a lipophobic property. The advantages described above with regard to a cooking appliance are achieved accordingly with such a viewing window.

Brief description of the drawings

The invention is explained below with reference to the attached

Drawings explained in more detail using preferred exemplary embodiments. The

Formulation Figure is abbreviated as Fig. in the drawings.

Show in the drawings

12 BE2022/5079

Fig. 1a is a schematic sectional view through a cooking appliance according to one

aspect of the invention;

Fig. 1b shows a detail from Fig. 1a;

Fig. 1c shows a further detail from Fig. 1a;

2a shows a schematic representation of a viewing window for a cooking appliance according to an aspect of the invention in a first embodiment;

Fig. 2b shows a schematic representation of a viewing window for a cooking appliance according to one aspect of the invention in a second

embodiment; and

Fig. 2c is a schematic representation of a viewing window for a cooking appliance according to an aspect of the invention in a third embodiment.

Detailed description of the exemplary embodiments

The exemplary embodiments described are merely examples that can be modified and/or supplemented in a variety of ways within the scope of the claims.

Each feature described for a particular embodiment may be used alone or in combination with other features in any other embodiment. Any feature that is described for an embodiment of a particular claim category can also be described in a corresponding manner in an embodiment of another

Claim category can be used.

Figure 1a shows a cooking appliance 1 designed as an oven with a housing (not shown) and a cooking space 3 arranged in the housing.

The oven is in particular in a manner not shown with a

Equipped with a steam cooking function and a pyrolysis function. The cooking chamber 3 is connected to an upper side by a first cooking chamber wall 4.1, to a lower side by a second cooking chamber wall 4.2, to a front side by a third cooking chamber wall 4.3 and to a rear side by a

13 BE2022/5079 fourth cooking chamber wall 4.4 is limited, with the cooking chamber 3 still being limited to a right side and a left side by cooking chamber walls, not shown. A food support 5 is arranged in the cooking space 3 and the food 6 rests on it. The cooking space walls 4.1, 4.2, 4.4 can be insulated from the housing in a manner not shown.

The third cooking chamber wall 4.3 is formed by a cooking chamber door 7, whereby the

Cooking chamber door 7 can be swung open to open or close an opening 8 of the cooking chamber 3. The cooking chamber door 7 has a handle 7.1 and a second viewing window 9.2 embedded in it, the second viewing window 9.2 being designed as the inner one of three panes of multiple glazing and being sealed against the first cooking chamber wall 4.1 by means of a door seal 10.

The door seal 10 is made in particular from glass fiber.

A camera 15 is arranged above and outside the cooking chamber 3, which is surrounded by a cooling air volume 16, in which, for example, cooling air compressed by a compressor (not shown) circulates, such as by means of two

indicated by arrows. The cooling air can be cooled using means not shown, such as a heat exchanger and/or a heat pump. Between the camera 15 and the cooking chamber 3 there is a first viewing window 9.1 in the first

Cooking chamber wall 4.1 embedded, wherein the first viewing window 9.1 can be sealed from the first cooking chamber wall 4.1 by means of a seal, not shown. The first viewing window 9.1 borders the cooking chamber 3 with one side of the cooking chamber and the side facing away from the cooking chamber 3

Cooling air volume 16. The camera 15 is directed downwards and observes the food 6 located in the cooking chamber 3 through the first viewing window 9.1, as indicated by a viewing cone of the camera 15.

Figure 1b is a detailed view from Figure 1a, in which the area around the camera 15 is shown. It can be seen that the first viewing window 9.1 is formed by a transparent substrate 20 and a ceramic layer 21 applied thereto. The hydrophilic ceramic layer 21 extends over the entire first viewing window 9.1 and results in a reduced contact angle between

14 BE2022/5079 water adhering to the first viewing window 9.1 and the first viewing window 9.1, so that the water causes no or significantly reduced impairment of the visibility through the first viewing window 9.1. In the same way as in

The first viewing window 9.1 is shown in Figure 1b and is shown in Figure 1c

Detailed view from Figure 1a shown, which shows the cooking chamber door 7. Here it can be seen that the second viewing window 9.2 also consists of a substrate 20 and one applied to the substrate 20 with the same effect

Ceramic layer 21 is formed.

Figures 2a to 2c show different embodiments of the first

Viewing window 9.1 and/or the second viewing window 9.2 in a side section.

The viewing windows 9.1, 9.2 each have a substrate 20, whereby the

Substrate 20 is designed to be transparent. For example, the substrate 20 is off

Glass formed. In a first embodiment according to Figure 2a is on the

A ceramic layer 21 is applied to the substrate, the ceramic layer 21 having a transparent layer thickness d. In a second embodiment according to

2b, a carrier layer 22 is applied to the substrate, whereby the

Carrier layer 22 is in turn formed in a transparent layer thickness.

A ceramic layer 21 is again applied to the carrier layer 22 in a transparent layer thickness d, which can be designed corresponding to the ceramic layer 21 according to FIG. 2a. In a third embodiment according to

Figure 2c shows a combined layer 23 on the substrate 20, consisting of a carrier material and one introduced on or in the carrier material

Ceramic oxide applied. Such a combined layer represents in the sense of

Invention represents a ceramic layer.

Furthermore, in Figures 2a to 2c there is one on the surface of the

Water drop 24 located in the ceramic layer 21 is shown, in which wetting occurs due to the hydrophilic properties of the ceramic layer 21, i.e. the water drop 24 assumes a very small contact angle relative to the surface of the ceramic layer 21, so that the surface of the water drop 24 is approximately parallel to the surface of the ceramic layer 21 runs.

In addition to the water drop 24, an oil drop 25 is also shown, which, if the ceramic layer 21 has lipophobic properties, cannot wet its surface, but instead assumes a drop shape with a very large contact angle.

The oil drop 25 can therefore not adhere to the surface of the ceramic layer 21 and contaminate it.

16 BE2022/5079

List of reference symbols 1 cooking appliance 3 cooking chamber 4.1 first cooking chamber wall 4.2 second cooking chamber wall 4.3 third cooking chamber wall 4.4 fourth cooking chamber wall 5 food support 6 food 7 cooking chamber door 7.1 handle of the cooking chamber door 8 opening 9.1 first viewing window 9.2 second viewing window 10 door seal 15 camera 16 cooling air volume

Substrate 21 ceramic layer 20 22 carrier layer 23 combined layer 24 water drops

Oil drop d layer thickness 25

Claims (1)

17 BE2022/5079 patent claims 1. Cooking appliance (1) with a housing and a cooking space (3) arranged in the housing, the cooking space (3) being delimited by cooking space walls (4.1, 4.2, 4.3, 4.4), in a first area of the cooking space walls (4.1, 4.2, 4.3, 4.4) a first viewing window (9.1, 9.2), the first viewing window (9.1, 9.2) being formed by a transparent substrate (20) and a hydrophilic ceramic layer (21) applied to the substrate (20) on the cooking chamber side, the ceramic layer (21) having a transparent layer thickness ( d) is formed, and wherein the ceramic layer (21) has a lipophobic property. 2. Cooking appliance (1) according to claim 1, having an opening (8) for filling the cooking space (3) and at least one cooking space door (7) for closing the opening (8), the cooking space door (7) forming a cooking space wall (4.3). and the first viewing window (9.2) is embedded in the cooking chamber door (7). 3. Cooking appliance (1) with a housing and a cooking space (3) arranged in the housing, the cooking space (3) being delimited by cooking space walls (4.1, 4.2, 4.3, 4.4), in the housing outside the cooking space (3) a camera (15) is arranged for observing the cooking chamber (3), and wherein in a first area of the cooking chamber walls (4.1, 4.2, 4.3, 4.4) there is a first viewing window (9.1) between the camera (15) and the cooking chamber (3) is embedded, characterized in that the first viewing window (9.1) is formed by a transparent substrate (20) and a hydrophilic ceramic layer (21) applied to the substrate (20) on the cooking chamber side, the ceramic layer (21) having a transparent layer thickness (i.e ) is trained. 4. Cooking appliance (1) according to one of the preceding claims, wherein a second viewing window (9.2) is embedded in a second area of the cooking chamber walls (4.1, 4.2, 4.3, 4.4), the second viewing window (9.2) being through a 18 BE2022/5079 transparent substrate (20) and a hydrophilic ceramic layer (21) applied to the substrate (20) on the cooking chamber side is formed, and wherein the ceramic layer (21) is formed in a transparent layer thickness (d). 5. Cooking appliance (1) according to claim 4, comprising at least one camera (15) arranged outside the cooking space (3) for observing the cooking space (3), an opening (8) for filling the cooking space (3) and at least one cooking space door (7 ) for closing the opening (8), the cooking chamber door (7) forming a cooking chamber wall (4.3), the first viewing window (9.1) being embedded between the camera (15) and the cooking chamber (3) in a cooking chamber wall (4.1) and wherein the second viewing window (9.2) is embedded in the cooking chamber door (7). 6. Cooking appliance (1) according to claim 4 or 5, wherein the ceramic layer (21) of the second viewing window (9.2) has a lipophobic property. 7. Cooking appliance (1) according to one of claims 3, 5 or 6, wherein a first viewing window (9.1) embedded between the camera (15) and the cooking space (3) in a cooking space wall (4.1) extends in a horizontal plane. 8. Cooking appliance (1) according to one of claims 2, 5 or 6, wherein a first viewing window (9.2) or second viewing window embedded in the cooking chamber door (7). (9.2) extends in a vertical plane. 9. Gargerâät (1) according to one of claims 2, 5, 6 or 7, having a door seal (10) for sealing the opening (8) closed by the cooking chamber door (7) from an environment of the cooking appliance (1), the door seal (10) is made in particular from glass fiber. 10. Cooking appliance (1) according to one of the preceding claims 1 to 9, wherein the ceramic layer (21) of the first viewing window (9.1, 9.2) and / or the second viewing window (9.2) is formed as a ceramic oxide layer, for example with zirconium oxide, titanium dioxide and / or aluminum oxide is. 19 BE2022/5079 11. Cooking appliance (1) according to one of the preceding claims 1 to 9, wherein the ceramic layer (21) of the first viewing window (9.1, 9.2) and / or the second viewing window (9.2) is designed as a non-oxide ceramic layer, for example with silicon carbide, silicon nitride, titanium nitride . 12. Cooking appliance (1) according to one of the preceding claims, wherein the layer thickness (d) of the ceramic layer (21) of the first viewing window (9.1, 9.2) and / or the second viewing window (9.1) is between 50 nanometers and 1500 nanometers. 13. Cooking appliance (1) according to one of the preceding claims, wherein the ceramic layer (21) of the first viewing window (9.1, 9.2) and / or the second viewing window (9.2) forms a contact angle with water of less than 15°, in particular less than 12°. 14. Cooking appliance (1) according to one of the preceding claims, wherein the ceramic layer (21) of the first viewing window (9.1, 9.2) and / or the second viewing window (9.2) by a sol-gel process, a PVD process, a CVD - Process and/or a PECVD process is applied. 15. Cooking appliance (1) according to one of the preceding claims, wherein at least one of the first viewing window (9.1, 9.2) and the second viewing window (9.2) has a structuring of the surface on the cooking chamber side. 16. Viewing window (9.1, 9.2) for a cooking appliance (1) according to one of the preceding claims, comprising a transparent substrate (20) and a hydrophilic ceramic layer (21) applied to the substrate (20), the ceramic layer (21) being in one transparent layer thickness (d) is formed and wherein the ceramic layer (21) has a lipophobic property.