Patent Application
20250052427
Priority is claimed to German Patent Application No. DE 10 2023 121 283.4, filed on Aug. 9, 2023, the entire disclosure of which is hereby incorporated by reference herein.
The invention relates to a cooking appliance comprising a housing having a cooking chamber delimited by a housing wall and a first viewing opening in the housing wall arranged above the cooking chamber, a camera device arranged above the first viewing opening for observing the cooking chamber with an image sensor and a lens defining an optical axis, and a heating device for heating food to be cooked that is placed in the cooking chamber, and/or a high-frequency generator for heating food to be cooked that is placed in the cooking chamber by means of microwave radiation.
Cooking appliances, in particular ovens with a microwave function (referred to as combination appliances), are known from the prior art. Cooking appliances with camera devices are also known in which a camera image allows the user to visually check the cooking status of the food to be cooked, for example when the cooking chamber door is closed, or which is used to identify a specific food to be cooked and to control various functions of the cooking appliance based thereon. For example, predefined cooking programs are started by the cooking appliance depending on the detected food to be cooked or, to achieve optimal cooking results, parameters of a cooking program are automatically adapted to the particular cooking state of the food to be cooked, which is recorded by means of an image analysis.
In principle, it is necessary to protect the camera device from excessive temperatures to avoid damaging it. Such damage threatens many camera devices or their lenses at temperatures from about 120° C. It is therefore already known to arrange the camera device outside the cooking chamber and to thermally decouple it therefrom, for example from publications EP 3 714 210 B1, EP 3 205 941 B1, WO 2023/110746 A1 and U.S. Pat. No. 8,660,297 B2.
In cooking appliances with a microwave function, in conjunction with the integration of camera devices, the problem also results that the camera electronics are extremely sensitive to microwave radiation. Depending on the intensity of the radiation, this can lead to disruptions in the recording of images and even irreparable damage, in particular to the image sensor. In addition, microwave radiation can escape through an opening through which the camera device looks into the cooking chamber.
In an embodiment, the present invention provides a cooking appliance, comprising: a housing having a cooking chamber delimited by a housing wall and a first viewing opening in the housing wall arranged above the cooking chamber; a camera device arranged above the first viewing opening, the camera device comprising an image sensor and a lens, the lens defining an optical axis for observing the cooking chamber; a heating device configured to heat food to be cooked placed in the cooking chamber and/or a high-frequency generator configured to heat food to be cooked placed in the cooking chamber by microwave radiation; and a shielding channel extending between the camera device and the first viewing opening so as to shield the camera device from heat and/or microwave radiation, wherein the first viewing opening is covered by a first viewing pane, and a second viewing pane is arranged at an upper end of the shielding channel, wherein an air chamber is formed between the shielding channel and the camera device, wherein an air supply configured to supply cooling air into the air chamber is arranged on the air chamber, wherein the air supply comprises a nozzle, and wherein the lens is at least partially arranged in the air chamber.
Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following:
In an embodiment, the present invention provides a cooking appliance having a camera device in which the camera device is sufficiently protected against damage.
To the extent that elements are designated by means of numbering, for example “first element,” “second element” and “third element,” this numbering is solely intended for differentiation in designation and does not indicate any dependency of the elements on one another or a mandatory order of the elements. This means in particular that, for example, a device or a method does not have to have a “first element” in order to be able to have a “second element”. The device or the method can also have a “first element” and a “third element”, but without necessarily having a “second element”. It is also possible to provide a plurality of units of an element of a single numbering, for example a plurality of “first elements.”
According to a first aspect of the invention, the object is achieved by a cooking appliance comprising a housing having a cooking chamber delimited by a housing wall and a first viewing opening in the housing wall arranged above the cooking chamber, a camera device arranged above the first viewing opening for observing the cooking chamber, a heating device for heating food to be cooked placed in the cooking chamber and/or a high-frequency generator for heating food to be cooked placed in the cooking chamber by means of microwave radiation, and a shielding channel extending between the camera device and the first viewing opening for shielding the camera device from heat and/or microwave radiation, wherein the first viewing opening is covered by a first viewing pane, and a second viewing pane is arranged at the upper end of the shielding channel, wherein an air chamber is formed between the shielding channel and the lens, and wherein an air supply for supplying cooling air to the air chamber is arranged on the air chamber:
A cooking appliance is designed in particular as an oven having a microwave function, in which temperatures of approximately 100-250° C. are provided in the cooking chamber for the preparation of food to be cooked. In particular, the cooking appliance therefore comprises a conventional heating device with top heat, bottom heat and/or circulating air heating means. The cooking appliance can in particular also be designed as an oven having a pyrolysis function and/or a steam cooking function. With a pyrolysis function, for example, temperatures between 400° C. and 500° C. are reached in the cooking chamber. The cooking appliance can also be designed as a microwave oven. The high-frequency generator comprises in particular a magnetron or a solid-state microwave generator and can, for example, expose the cooking chamber to microwave radiation, or couple microwave radiation into the cooking chamber.
The cooking chamber of the cooking appliance is designed as a cavity in the housing of the cooking appliance insulated from an outer wall of the cooking appliance by means of thermal insulation. Preferably, the cooking chamber can be filled with food to be cooked via an opening, or such food to be cooked can be removed from the cooking chamber via the opening, wherein the opening can be closed, for example, by means of a cooking chamber door. In or on the cooking chamber, means for heating the cooking chamber are provided, for example, means for radiating heat, for convective transfer of heat, for transferring heat by means of heat conduction and/or for transferring heat by means of induction, as well as means for circulating the air in the cooking chamber. “Heating” is understood to mean both increasing and maintaining a cooking chamber temperature with simultaneous heat loss, for example through waste heat.
The camera device is arranged outside the cooking chamber, wherein a first viewing opening is embedded in a housing wall through which the camera device can observe the cooking chamber. The viewing opening is dimensioned and positioned such that it spans a region of a viewing cone of the camera device and is transparent in this region. The camera device is arranged above the cooking chamber and looks from above at the region that is provided for the arrangement of the food to be cooked. The camera device comprises, for example, a 2D camera, but can alternatively or additionally also have a 3D camera, for example designed as a TOF camera.
The shielding channel extends in particular coaxially to the optical axis and has, for example, at least sectionally, a rectangular channel cross section and/or, at least sectionally, a round channel cross section. In this way, the shielding channel forms a waveguide at least sectionally, which attenuates the microwave radiation with the wavelengths typically used in cooking appliances, for example greater than or equal to 12 cm at a frequency of around 2.45 GHz, or 32 cm at a frequency of 915 MHz, along its longitudinal extent. Typical microwave frequencies are effectively shielded by this easily implemented structural design of the shielding channel, wherein only leakage radiation of negligible magnitude reaches the camera electronics. At the same time, the field of view of the camera device can remain largely free, which allows for reliable recording of meaningful images of the cooking chamber.
Preferably, the shielding channel tapers from the cooking chamber toward the camera device, i.e. in the shape of a funnel, so that the attenuation of the microwave radiation is further increased due to the tapered channel cross section. For the exact design of the cross-sectional geometries, depending on the selected shape of the (section of the) shielding channel, a waveguide having a corresponding cross-sectional geometry can be used, which is impassable for the relevant wavelength. For example, the shielding channel can have the shape of a pyramid or truncated cone at least sectionally, such that the first camera channel cross-section has a rectangular, circular or elliptical shape. Other cross-sectional shapes, such as polygons, are also conceivable.
Furthermore, this design makes it possible to create space beyond the channel cross-section, which widens congruently to the tapering channel cross-section. This space, which increases with distance from the cooking chamber, allows advantageous insulation against the heat in the cooking chamber.
Furthermore, the shielding channel defines a spatial distance between the first viewing pane and the second viewing pane.
Achieving the object with the cooking appliance described above therefore includes the teaching that, on the one hand, a shielding channel is provided that protects the camera device from damage caused by heat and/or microwave radiation that would reach the electronics of the camera device. On the other hand, the overall arrangement of the shielding channel, the viewing openings or viewing panes and the air chamber, which is actively cooled by means of the air supply or allows active cooling of the camera device, allows for in particular good thermal decoupling of the camera device from the cooking chamber, so that the camera device is also protected against damage caused by high temperatures. In particular, an insulating space is created between the first viewing pane and the second viewing pane. Overall, a cooking appliance is therefore provided in which the camera device is protected against damage for a plurality of functions, in particular comprising a microwave function and a pyrolysis function. In this case, achieving the object with the proposed cooking appliance is also structurally simple, inexpensive and durable.
In one embodiment of the cooking appliance, the air supply comprises a nozzle, wherein the nozzle is directed in particular toward a lens of the camera device, preferably in such a way that the lens is exposed to airflow from the side, i.e. substantially horizontally.
One aspect is that the airflow is oriented by means of the orientation of the nozzle, wherein the direction of the airflow is defined by a blowing axis of the nozzle, or by a deflection angle of the nozzle and a blowing axis of the nozzle.
The blowing axis encloses an angle with a normal plane of the optical axis, which angle is preferably at least 3 degrees and is in particular in a range of 5 degrees to 30 degrees.
Preferably, the airflow is free from fanning out. However, it is also possible that the nozzle is configured and designed in such a way that the airflow is fanned out by the nozzle. The nozzle has a deflection angle which defines the extent of the maximum deflection of the airflow from the blowing axis, and thus the extent to which the airflow fans out.
The deflection angle is preferably small, in particular an airflow that is free from fanning out has a deflection angle of 0 degrees. It has proven particularly advantageous that the deflection angle is less than 25 degrees, in particular the deflection angle is in a range of 5 degrees to 20 degrees.
In particular, a nozzle concentrates and accelerates the airflow of the cooling air so that components can be cooled in a targeted and in particular efficient manner by means of forced convection, or so that an air barrier can be formed in the air chamber. By directing the nozzle at the lens, this particularly damage-prone and temperature-sensitive component is cooled in a targeted and in particular efficient manner. In particular, the efficient cooling with the nozzle allows a relatively low airflow to be set to achieve sufficient cooling so that sufficient cooling is achieved cost-effectively and easily.
In a further embodiment, the cooking appliance has a camera housing having a second viewing opening, in particular wherein the camera device is arranged at least partially above the second viewing opening, i.e. further away from the cooking chamber than the second viewing opening. For example, the air chamber and the air supply are then arranged in the camera housing, while the shielding channel is arranged between the camera housing and the housing wall delimiting the cooking chamber. Particularly advantageously, the camera housing can be pre-assembled outside the cooking appliance and then inserted into the cooking appliance so that there is no need to arrange the individual components within the cramped cooking appliance. In addition, the camera housing can then be easily removed from the cooking appliance for maintenance, repair or replacement.
One aspect is that the entire camera device is arranged completely above the second viewing opening. In this case, the lens is at a distance from the plane of the lower wall of the camera housing. It is also possible that the distance from the lens to the plane of the lower wall of the camera housing is zero. However, it is also possible that the camera device is only partially arranged above the second viewing opening, in particular at least with its center of gravity. This also allows the lens to partially penetrate through the second viewing opening in the lower wall of the camera housing.
One aspect is that the second viewing pane is arranged at a distance from the second viewing opening, wherein the second viewing pane is positioned closer to the first viewing pane than the second viewing opening. In particular, the distance between the second viewing opening and the second viewing pane is greater than one tenth of the distance between the second viewing pane and the first viewing pane. This can prevent the airflow provided for cooling the lens from being unnecessarily heated by the second viewing pane because the second viewing pane is at a distance from the air chamber carrying the air.
Preferably, at least the wall of the camera housing in which the second viewing opening is arranged is made of mica. Mica has particularly favorable thermal properties compared to alternative materials, in particular a relatively low thermal conductivity, good thermal stability, and high tolerance to temperatures without mechanical influence, so that the heat transfer between the cooking chamber and the camera device can be further reduced. To ensure that heat transfer through the lower wall of the camera housing is as low as possible, it is preferably constructed from an appropriate material. Mica is just one solution. The bottom wall could also be made of plastics material or silicone, although plastics material is preferred.
One aspect is to equip the lower wall of the camera housing, i.e. the wall in the region of the second viewing pane or the wall that is closest to the second viewing pane, with targeted openings to the space below. The space below the lower wall of the camera housing is limited in the direction of the cooking chamber by the shielding channel and/or the second viewing pane. The openings can cause a slight overpressure in the air-filled space above the lower wall of the camera housing compared to the region of the appliance insulation or the space below the lower wall of the camera housing. Likewise, the slight overpressure in the air-filled space above the lower wall of the camera housing can also occur relative to the air-filled space in the shielding channel. A slight overpressure is defined as an additional pressure of less than one bar. The slight overpressure prevents vapors from the cooking chamber from penetrating and condensing through possible leaks or from the region of the appliance insulation.
Particularly preferably, a first seal, in particular a fiberglass seal, is arranged between the shielding channel and the camera housing. In this way, the inner region of the shielding channel or the second viewing pane is sealed against an adjacent outer region of the cooking chamber and is protected in particular against contamination by fibers of a thermal insulation arranged there. A fiberglass seal also prevents a thermal bridge between the shielding channel and the camera housing.
In a further embodiment of the cooking appliance, the shielding channel and the housing together form a plurality of contact points around the circumference of the shielding channel, wherein the shielding channel and the housing are contact-free between the contact points. In this way, a stable connection is created between the shielding channel and the housing or the housing wall, so that the shielding channel is fixed in its position and cannot shift even when installing/removing the camera housing or the camera device. At the same time, the contact surface between the shielding channel and the housing or housing wall is reduced to a necessary minimum in order to reduce the heat conduction between the two components as much as possible. The contact points are designed, for example, as welding points, screw connections and/or pin connections, in particular rivet connections. In particular, the distance of the contact points from each other is chosen such that microwave radiation of the relevant frequencies and wavelengths cannot pass through the gaps formed between the contact points.
Preferably, a second seal is arranged in the region of the contact points and/or between the shielding channel and the housing. This is arranged, for example, between the contact points, around the contact points, outside or inside the contact points, in particular around the shielding channel. In this way, the inner region of the shielding channel or the viewing panes is sealed against an adjacent outer region of the cooking chamber and is protected in particular against contamination from fibers of a thermal insulation arranged there. In addition, by choosing an appropriate insulating sealant, a thermal bridge between the shielding channel and the housing or housing wall is avoided.
One aspect is that the second seal is arranged between the first viewing pane and the second viewing pane. Preferably, the second seal is at a distance from the first viewing pane that is greater than one tenth, in particular greater than one third, of the distance between the first viewing pane and the second viewing pane.
The various features described above and their totality result in low heat transfer between the housing and the camera device so that a correspondingly small distance can be selected between the camera device and the housing without the risk of damage to the camera device. Advantageously, the viewing openings can be selected to be relatively small given a large viewing cone the camera device.
In a particularly preferred embodiment of the cooking appliance, the second viewing pane has an electrically conductive transparent layer, wherein the electrically conductive transparent layer is in galvanic contact with the shielding channel. In this way, the leakage radiation of microwave radiation that reaches the camera device is further reduced. In addition, the transparent layer causes a reflection of infrared radiation emitted from the cooking chamber so that the heat input from this infrared radiation to the camera device is reduced.
Preferably, the electrically conductive transparent layer is formed as an indium tin oxide coating, as a coating of fluorine-doped tin oxide, or as a metal grid. These materials offer good transparency so that the view of the camera device is not obstructed to any significant extent. At the same time, these materials offer good electrical conductivity and thus advantageous shielding of the camera device against leakage radiation.
The metal grid can be designed as a coating on the second viewing pane. It is also possible for the metal grid to be embedded in the second viewing pane. Preferably, the metal grid is not part of the second viewing pane but is a separate part that is arranged at a distance from the second viewing pane in the shielding channel. Regardless of the specific embodiment, the metal grid is galvanically connected to the shielding channel, in particular attached to the preferably metal shielding channel by a welded connection. Furthermore, an opaque electrically conductive layer is preferably formed in an edge region of the second viewing pane. This layer then lies outside the viewing cone of the camera device and therefore does not need to have transparent properties. The layer can then be simpler and more cost-effective than the transparent layer and provide the contact between the transparent layer and the shielding channel. For example, the opaque layer is formed by a metallically conductive film or by a metallically conductive lacquer applied in particular by screen printing.
One aspect is that the opaque electrically conductive edge coating is applied to the thin transparent coating. The edge coating serves in particular to protect or reinforce the transparent coating in the edge region. This is intended, for example, to prevent the thin transparent layer from being damaged by movement of the third seal.
Another aspect is that the conductive lacquer is designed as a paste that contains silver particles. After printing, said paste is sintered with the application of heat, for example in an oven, so that it forms a solid conductive connection to the coating of the pane.
Furthermore, an electrically conductive third seal is preferably arranged between the second viewing pane and the shielding channel, wherein the third seal forms the galvanic contact between the electrically conductive transparent layer and the shielding channel. For this purpose, the third seal can be in contact with the opaque layer and/or the transparent layer. For example, the third seal is formed from a metal mesh or from a silicone containing metal particles. Seals of metal mesh are formed from knitted, very thin wire that is pressed into a mold. A silicone containing metal particles has the advantage that the third seal, in addition to establishing the galvanic contact, also serves as a barrier against environmental influences and against the penetration of fibers from a thermal insulation arranged outside the cooking chamber.
In a particularly preferred embodiment, the camera device has an image sensor and a lens defining an optical axis, wherein the shielding channel has a first channel cross section having a cross sectional geometry that is impassable for microwave radiation having a wavelength greater than or equal to 12 cm at a microwave frequency of around 2.45 GHz, or for microwave radiation having a wavelength greater than or equal to 32 cm at a microwave frequency of around 915 MHz at a distance from an end of the lens facing the cooking chamber, which distance is measured parallel to the optical axis. These wavelengths or microwave frequencies represent the sizes most commonly used in cooking appliances, against which effective shielding is thus created. In a preferred embodiment of the invention, the distance from the first camera channel cross section to the end of the lens facing the cooking chamber is 20 mm to 50 mm, preferably 25 mm to 40 mm. Surprisingly, it has been found that with such distances of this size, a compact design with effective shielding of the microwave radiation can be achieved.
As already in part described above, the shielding channel is funnel-shaped, at least sectionally. In this way, effective attenuation of microwave radiation can be achieved using simple design means. Funnels having a rounded cross-sectional shape, such as an elliptical, oval or circular cross-sectional shape (truncated cone-shaped funnel), and having an angular cross sectional shape, such as a rectangular cross sectional shape (truncated pyramid-shaped funnel) or polygonal cross sectional shapes, are possible in this regard.
It has proven advantageous for all non-transparent components in the optical path of the camera to be low-reflection or matt black or coated. This prevents artifacts in the image that could otherwise be caused by a reflection from, for example, the cooking chamber lighting. This design or coating is provided in particular in the shielding channel, and/or in the funnel-shaped section of the first housing wall, and/or in the holder, and/or in the lower wall of the camera housing, and/or in a grid in the shielding channel.
In a preferred embodiment, the cooking appliance has a cooling air apparatus for providing cooling air, wherein the provided cooling air is supplied via the air supply to the air chamber and further to the high-frequency generator for its cooling. In this way, cooling air from a separate air circuit is advantageously supplied to both the camera device or the air chamber and the high-frequency generator, wherein it can be ensured that this cooling air is largely free of contaminants and in particular free of vapors from the cooking chamber. In order to cool the camera device sufficiently, relatively low airflows at relatively high temperatures can be sufficient, for example an airflow of at least 5 m/s with a round cross section of the air supply of 10 mm and at a cooling air temperature of no more than 85° C. Alternatively, a separate sensor cooling circuit can be provided for the camera device or the air chamber, which is only assigned to the camera device and, for example, draws in ambient air of the appliance or air from cooler regions within the appliance housing.
A further seal is preferably provided between the first viewing pane and the housing, which further seal is in particular designed to be elastic in order to compensate for dimensional tolerances and thermal expansion. Such an additional seal has the advantage of reliably preventing vapors from the cooking chamber from entering the shielding channel.
The third housing wall 4.3 is formed by a cooking chamber door 7, wherein 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 is made of multiple glazing, has a handle 7.1 and is scaled against the first housing wall 4.1 by means of a seal 7.2.
A camera device 15 is arranged above and outside the cooking chamber 3 and is designed for observing the cooking chamber 3 or the food to be cooked 6, and only rudimentary details of the invention are initially shown with regard to its arrangement in
The cooking appliance 1 has a schematically illustrated heating device 14 and/or a schematically illustrated high-frequency generator 13 for heating food to be cooked 6 placed in the cooking chamber 3. The heating device 14 can be designed, for example, with top heat, bottom heat and/or circulating air heating means, which is not shown in more detail.
A shielding channel 23 is arranged between the camera housing 20 and the first housing wall 4.1, and thermal insulation 24 is arranged on both sides of the shielding channel 23. The shielding channel 23 extends between a funnel-shaped portion 4.5 of the first housing wall 4.1 and the camera housing 20 and has an electrically conductive inner wall. The funnel-shaped portion 4.5 forms the first viewing opening 10.1 and is covered on its underside by the first viewing pane 9.1 held by means of a holder 28. A first seal 25.1 designed as a fiberglass seal is arranged between the camera housing 20 and the shielding channel 23. A second seal 25.2 is arranged between the shielding channel 23 and the funnel-shaped portion 4.5, wherein relevant details are shown in
A second viewing pane 9.2 is arranged at the upper end of the shielding channel 23, wherein an insulating air-filled chamber 30 is formed between the first viewing pane 9.1 and the second viewing pane 9.2, which is further defined by the funnel-shaped portion 4.5 and the shielding channel 23. A conductive transparent layer 29 is arranged on the second viewing pane 9.2. In the embodiment according to
While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. It will be understood that changes and modifications may be made by those of ordinary skill within the scope of the following claims. In particular, the present invention covers further embodiments with any combination of features from different embodiments described above and below. Additionally, statements made herein characterizing the invention refer to an embodiment of the invention and not necessarily all embodiments.
The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 121 283.4 | Aug 2023 | DE | national |
