Cooking appliance comprising an illuminating device having a plurality of freeform lenses
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-08-13
Smart Images
Figure EP2026052114_13082026_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Cooking appliance with a lighting device featuring multiple free-form lenses
[0003] The invention relates to a cooking appliance with a cooking chamber bounded by walls and closable by a door, a receiving system arranged in the cooking chamber for receiving the food carrier in one of several receiving levels, and a lighting device comprising a light source and designed to illuminate the food carrier received in the receiving system and at least partially extended from the cooking chamber. Such lighting devices can also be referred to as anteroom lighting. Typically, the light sources used are luminaires, such as LEDs, which exhibit a radiation pattern in which the intensity of the radiation is maximum along a defined optical axis or the normal direction and decreases with increasing beam angle relative to the optical axis (Lambert's law).The light is emitted in the form of a cone, resulting in a largely rotationally symmetrical light distribution. This creates the problem that the cooking tray, which typically has a rectangular surface, is illuminated unevenly. If the cone is too small, this leads to shadows and insufficient visibility of certain areas of the tray. If the cone is too large, some of the light is directed past the tray, causing reflections that detract from the aesthetic appearance of the cooking appliance and the kitchen, and can also dazzle the user.
[0004] German patent application DE 102017219497 A1 discloses a lighting device for an oven in which a simple geometric lens is arranged above the oven opening at a fixed distance from the extended cooking tray. The light cone can be limited to the shape of the cooking tray by means of an aperture.
[0005] The publication DE 102012224034 A1 shows several identical systems consisting of a light source and lens for illuminating the surface of a cooking tray, each illuminating a partial area of the cooking tray.
[0006] Since the cooking tray can be inserted and removed into the different mounting levels of the mounting system and thus into different height positions, the lighting must be designed flexibly in order to optimally illuminate each of these positions.
[0007] The invention therefore addresses the problem of providing a cooking appliance with a lighting device that enables more uniform illumination of, in particular, rectangular food carriers, even if these can be positioned in different mounting planes.
[0008] According to the invention, this problem is solved by a cooking appliance with the features of claim 1. Advantageous embodiments and further developments of the invention are described in the following dependent claims.
[0009] The cooking device according to the invention is characterized in that each of the several recording planes is assigned a free-form lens of the lighting device, wherein each of the free-form lenses has at least one free-form surface and is designed to direct light radiation emitted by the light source onto a cooking carrier surface of the cooking carrier received and extended in the respective assigned recording plane by means of light refraction.
[0010] The advantage achievable with the invention is that the use of freeform lenses results in a high degree of freedom in the design of the light distribution.
[0011] In particular, the light beam can be optimally adapted to the shape of the cooking tray to ensure ideal illumination. Furthermore, the freeform lenses require little installation space and are easy to integrate into the cooking appliance.
[0012] By using multiple freeform lenses, each lens can be aligned to optimally illuminate the food tray extended in its corresponding recording plane. This provides a lighting device that ensures uniform illumination of the food tray, regardless of its position in the recording plane.
[0013] Furthermore, it is ensured that the light-emitting surface on the cooking tray is of a similar geometric shape to the cooking tray, for example rectangular.
[0014] Furthermore, it is achieved that the light-emitting surface on the cooking carrier approximately coincides with the geometric boundaries of the cooking carrier; in particular, in the plane of the cooking carrier, the cross-sectional area of the light emission is at most 10 percent, preferably less than 5 percent, larger than the area of the cooking carrier.
[0015] Furthermore, it is achieved that the light-emitting surface on the cooking carrier approximately coincides with the geometric boundaries of the cooking carrier; in particular, in the plane of the cooking carrier, the cross-sectional area of the light emission is at most 10 percent, preferably less than 5 percent, smaller than the area of the cooking carrier.
[0016] Light direction in a freeform lens, as in any other lens, occurs through light refraction at a lens surface. In the case of a freeform lens, this is a complexly curved freeform surface. For the purposes of this invention, a freeform surface is understood to be, in particular, a lens surface that is non-rotationally symmetric and not planar. Complex freeform surfaces can typically be designed for specific applications using computer-aided numerical methods. The material of the freeform lens can, for example, be glass or plastic, such as polycarbonate or acrylic (polymethyl methacrylate, PMMA). Preferably, a rear surface of the freeform lens, opposite the freeform surface, is planar. This simplifies the manufacturing of the freeform lens. The fully extended position of the cooking tray is determined by the mounting system used.In this position, the cooking tray can be fully extended from the cooking chamber or still partially protrude into it. The mounting system can, for example, have a telescopic extension for the cooking tray at each mounting level, designed as a partial extension, full extension, or over-extension.
[0017] For the purposes of this invention, suitable cooking appliances include, in particular, ovens, steam cookers, microwave ovens and / or combination ovens with steam cooking and / or microwave functions. The cooking appliance according to the invention can be designed as a household appliance for use in private households or as a commercial appliance for professional use.
[0018] A preferred embodiment of the cooking device according to the invention provides that each free-form lens is designed to approximate the shape of the cooking carrier surface of the food carrier, which is received and extended in the respective associated receiving plane, by means of light refraction, compared to the light distribution exhibited by the light source or the lamp itself. In this way, the discrepancy between the round or rounded shape of the light cone and the rectangular shape of the cooking carrier can be significantly reduced. This counteracts shadow formation due to insufficient illumination as well as unfavorable light reflections due to excessive illumination.Preferably, the cooking carrier surface has a rectangular shape with four sides and four optionally rounded corners, wherein the freeform lenses are configured to compress the isolines of the light distribution relative to the isolines of the light distribution exhibited by the light source itself, in sections facing the center of one of the sides, towards a center of the light distribution, and / or to stretch them towards the corners in sections facing the corners. For the purposes of this invention, isolines are understood to be lines on the cooking carrier surface on which the same light intensity value occurs at every point. The light intensity value is also referred to as illuminance. By compressing the isolines, the curves of the light distribution of the light source are increasingly transformed into straight lines and adapted to the rectangular shape of the cooking carrier.Alternatively or additionally, the curves of the light distribution from the light source can be extended outwards in sections facing the corners of the cooking tray, so that they approximate the rectangular shape of the cooking tray. In particular, the cross-sectional contour of the light cone refracted in this way by the respective freeform lens and striking the surface of the cooking tray can be defined, at least in sections, by a superellipse or...
[0019] Hyperellipse can be described.
[0020] A further preferred embodiment of the cooking device according to the invention provides that the freeform lenses are designed to illuminate the surface of the food carrier, which is held in the respective associated recording plane and fully extended, in such a way that the light intensity in a centrally located inner region of the food carrier surface, comprising at least 50% of the surface area, corresponds to between 80% and 100% of the maximum light intensity of the light distribution. In particular, the centrally located inner region has a rectangular shape and is uniformly spaced from the sides of the food carrier. This illuminates a large area of the food carrier surface with a similar light intensity, thereby improving the visibility of the food carrier surface in an aesthetically pleasing manner.
[0021] A further preferred embodiment of the cooking device according to the invention provides that the freeform lenses are designed to illuminate the surface of the food carrier, which is held in the respective associated recording plane and fully extended, in such a way that the light intensity in a centrally located area of the food carrier surface, comprising at least 30% of the surface area, corresponds to between 90% and 100% of the maximum light intensity of the light distribution. In particular, the centrally located area has a rectangular shape and is uniformly spaced from the sides of the food carrier. This illuminates a substantial portion of the food carrier surface with nearly the same light intensity, thereby further improving the visibility of the food carrier surface.Another preferred embodiment of the cooking device according to the invention provides that the freeform lenses are designed to emit a maximum of 30%, preferably a maximum of 10%, of the total light intensity emitted by the lighting device away from the surface of the cooking carrier when the food carrier is fully extended and held in the respective associated recording plane. In other words, the amount of light that bypasses the cooking carrier is reduced. This results in fewer light reflections that could impair the aesthetic appearance of the cooking device and the kitchen or dazzle a user. Preferably, the freeform lenses are designed to emit the entire light intensity emitted by the lighting device onto the surface of the cooking carrier when the cooking carrier is fully extended. In other words, no light is bypassed by the cooking carrier.
[0022] Another preferred embodiment of the cooking device according to the invention provides that the freeform surfaces of the freeform lenses face the light source. In this way, the light refraction occurs closer to the light source, allowing the freeform lenses to capture more light. Furthermore, the lighting device can be designed more compactly.
[0023] A further preferred embodiment of the cooking appliance according to the invention provides that the cooking appliance has a detection device configured to detect in which of the several receiving planes the food carrier, at least partially extended from the cooking chamber, is received, and a control device configured to control the lighting device such that the light radiation emitted by the light source is guided through the free-form lens assigned to the detected receiving plane and directed onto the surface of the food carrier. The automatic, targeted illumination with the respective free-form lens ensures that the food carrier is optimally illuminated in each receiving plane. This guarantees uniform illumination and simultaneously offers a high degree of user-friendliness.Preferably, the detection device has at least one sensor designed to detect in which of several detection planes the food carrier, at least partially extended from the cooking chamber, is located. The sensor can, for example, be an occupancy sensor placed in the cooking chamber or in the respective detection plane, such as a capacitive, resistive, or inductive proximity sensor or a pressure sensor. Alternatively or additionally, an optical sensor, such as a camera, can be used, directed into the cooking chamber and / or the anteroom located in front of the cooking chamber. In principle, the detection of the food carrier's detection plane and the detection of its extended position can be performed independently of each other.For example, the information regarding which of the several mounting levels the cooking tray is positioned in can be specified by a selected operating program, so that this information can be processed by the detection device and only the ejection position of the cooking tray needs to be detected by a suitable sensor. The detection device and control device can be separate hardware or implemented on a common hardware unit. Another preferred embodiment of the cooking device according to the invention provides that each of the freeform lenses is assigned a light source, with each light source being designed to direct light rays exclusively onto its respective assigned freeform lens. This allows for targeted illumination with the respective freeform lens to be implemented in a structurally simple manner.
[0024] Another preferred embodiment of the cooking device according to the invention provides that the freeform lenses are arranged side by side along a horizontal line. This ensures a compact design of the lighting device, which can be easily integrated into the cooking device. In particular, the horizontal line extends along one of the widths of the cooking device. Preferably, the freeform lenses are arranged close together, with the distance between the freeform lenses measured along the line being less than or equal to 20 mm, preferably less than or equal to 10 mm, and most preferably less than or equal to 5 mm.
[0025] Another preferred embodiment of the cooking device according to the invention provides that the freeform lenses are arranged together on a transparent carrier plate. This achieves a compact design of the lighting device, which ensures stable and precise alignment of the lenses. At the same time, assembly and maintenance of the lighting device are simplified.
[0026] Another preferred embodiment of the cooking device according to the invention provides that each of the free-form lenses is assigned a flat light-emitting surface of the lighting device, facing away from the light source, from which light radiation can emerge from the lighting device to illuminate the surface of the food carrier that has been received and extended in the respective receiving plane. This allows for simpler manufacturing of the lighting device.
[0027] Furthermore, the light-emitting surface is easy to clean due to its smooth surface. Preferably, the light-emitting surfaces are oriented at an angle between 20° and 80°, more preferably at an angle between 40° and 60°, to the optical axis of the light source or the respective luminaire. This allows for a compact design of the lighting device, which ensures efficient illumination of the cooking appliance's anteroom and can be easily integrated into the cooking appliance's control panel. The light-emitting surface of a given freeform lens can be formed by the freeform lens itself; that is, the rear surface of the freeform lens opposite its freeform surface serves as the light-emitting surface.If the freeform lenses are arranged together on a transparent carrier plate, the light-emitting surface of each freeform lens can also be located on the back side of the carrier plate. To ensure optimal illumination of the cooking tray from different positions, according to a further preferred embodiment of the cooking device according to the invention, at least one of the light-emitting surfaces is inclined relative to the recording planes by an angle of inclination between 1° and 10°. If, for example, two freeform lenses are arranged side by side along the width of the cooking device, a slight lateral offset occurs between the light cones or light pyramids of the different freeform lenses. This offset can be compensated for by the inclination of the respective light-emitting surface.
[0028] Preferably, at least two of the light emission surfaces are inclined relative to the recording planes at different angles of inclination and / or at different directions of inclination.
[0029] Another preferred embodiment of the cooking device according to the invention provides that the lighting device has at least one opaque partition arranged between two of the freeform lenses. This allows the freeform lenses to be optically separated from each other in a simple and compact manner, so that optimal illumination can be achieved by selectively illuminating the food carrier with the appropriate freeform lens.
[0030] An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows
[0031] Figure 1a shows an embodiment of a cooking appliance according to the invention in a partial side view;
[0032] Figure 1b shows the embodiment from Figure 1a with a varied recording plane in a side partial view;
[0033] Figure 2a shows a detail of the lighting device of the cooking appliance from Figures 1a and 1b;
[0034] Figure 2b shows a further detail of the lighting device of the cooking appliance from Figures 1a and 1b;
[0035] Figure 2c shows a further detail of the lighting device of the cooking appliance from Figures 1a and 1b;
[0036] Figure 3 shows the illuminated cooking tray of the cooking appliance from Figures 1a and 1b according to one embodiment of the invention in a top view; Figure 4 shows the illuminated cooking tray of the cooking appliance from Figures 1a and 1b according to a further embodiment of the invention in a top view; and
[0037] Figure 5 shows a graphical comparison of the light distribution of the lighting device on a rectangular surface, both without and with freeform lenses.
[0038] Figures 1a and 1b show an embodiment of a cooking appliance 2 according to the invention, with a cooking chamber 10 bounded by walls and closable by means of a door 8. In this case, the cooking appliance 2 is designed as an oven. When used and arranged as intended, the cooking chamber 10 defines a vertical direction H, a horizontal direction B (directed into the plane of the figure), and a vertical direction T of the cooking appliance 2. The cooking appliance 2 has a receiving system 12 for receiving the food carrier 14 in one of several receiving planes E1, E2. The receiving planes E1, E2 extend parallel to the horizontal direction B and the vertical direction T. For receiving the food carrier 14, the receiving system 12 has, for example, a telescopic extension 16 in each receiving plane E1, E2 (see Figures 3 and 4). The telescopic extension 16 can be designed as a partial extension, full extension or over-extension.The cooking appliance further comprises a lighting device 20 (anteroom lighting) which includes a light source 22 and is designed to illuminate the food carrier 14, which is held in the receiving system 12 and at least partially extended from the cooking chamber 10. The lighting device 20 is arranged behind a control panel 4 of the cooking appliance 2. The food carrier 14 is designed in this case as a rectangular baking tray.
[0039] The choice of the receiving plane E1, E2, or height position in which the cooking tray 14 is placed during the cooking process typically depends on the type of dish and the desired cooking technique or the selected operating program. For example, the cooking tray 14 can be received in a first receiving plane E1, as shown in Figure 1a, or in a second receiving plane E2, as shown in Figure 1b. In Figures 1a and 1b, the cooking tray 14 is shown in its extended position, illuminated by the lighting device 20.
[0040] To ensure optimal illumination of the cooking carrier 14, each of the several receiving planes E1, E2 is assigned a freeform lens 28, 28a of the lighting device 20 (see Figure 2b), wherein each of the freeform lenses 28, 28a has at least one freeform surface 30, 30a and is designed to direct the light radiation emitted by the light source 22 onto a cooking carrier surface 140 of the cooking carrier 14, which is received and extended in the respective receiving plane E1, E2, by means of light refraction. By refraction of the light radiation emitted by the light source 22 at the respective freeform surface 30, 30a, the light distribution of the lighting device 20 can be approximated to the rectangular shape of the cooking carrier surface 140 of the cooking carrier 14, compared to the light distribution exhibited by the light source 22 itself.In this process, each freeform lens 28, 28a can be aligned so that it optimally illuminates the cooking carrier 14 in its respective recording plane E1, E2.
[0041] The cooking appliance 2 has a detection device 50 configured to detect in which of the several receiving levels E1, E2 the food carrier 14, which has been at least partially extended from the cooking chamber 10, is received. For this purpose, the detection device 50 has an occupancy sensor 51, 51a in each of the receiving levels E1, E2, which is configured to detect whether the food carrier 14 is received in the respective receiving level E1, E2 and whether the food carrier is in its extended position. The cooking appliance 2 also has a control device 40 configured to control the lighting device 20 such that the light radiation emitted by the light source 22 is guided through the freeform lens 28, 28a assigned to the detected receiving level E1, E2 and directed onto the surface 140 of the food carrier 14.The automatic targeted illumination with the appropriate freeform lens 28, 28a ensures that the cooking tray 14 is optimally illuminated in each recording plane E1, E2.
[0042] Figure 2a shows the lighting device 20 of the cooking appliance 2 in a side view, showing only a first light source 221 of the light source 22 and a first free-form lens 28 of the lighting device 20. The first light source 221 is, for example, an LED. The first free-form lens 28 is assigned to the first recording plane E1, i.e., the first free-form lens 28 optimally focuses the light emitted by the first light source 221 in the form of a light cone or light pyramid 23 onto the cooking tray 14 when the cooking tray 14 is positioned in the first recording plane E1 and is in its extended position (see Figure 1a).
[0043] The freeform surface 30 of the first freeform lens 28 faces the light source 22 or the first light source 221. In this way, the light refraction occurs closer to the light source 22, allowing the freeform lens 28 to capture more light and enabling the lighting device 20 to be designed more compactly as a whole. A rear surface 33 of the freeform lens 28, opposite the freeform surface 30, is flat and extends parallel to the recording planes E1, E2. The freeform lens 28 is mounted on a transparent support plate 26. The side of the support plate 26 facing away from the light source 22 forms a flat light-emitting surface 34 of the lighting device 20, from which light radiation can emerge from the lighting device 20 to illuminate the extended cooking tray 14.It has proven advantageous for the compactness of the lighting device 20 if the light emission surface 34 is oriented at an angle a between 20° and 80°, preferably at an angle a between 40° and 60°, to the optical axis A of the light source 22.
[0044] Figure 2b shows the lighting device 20 of the cooking appliance 2 in an isometric detail view. The first freeform lens 28 and a second freeform lens 28a are shown. The freeform lenses 28 and 28a are arranged side by side along a horizontal line L running parallel to the lateral direction B. The first light source 221 of the light source 22 is assigned to the first freeform lens 28. The light source 22 also has a second light source 222, e.g., in the form of an LED, which is assigned to the second freeform lens 28a and emits light radiation along a second optical axis A'. The second freeform lens 28a is assigned to the second receiving plane E2, i.e., the second freeform lens 28a focuses the light emitted by the second light source 222 by means of its freeform surface 30a in the form of a light cone.A light pyramid 23a is optimally directed onto the cooking tray 14 when the cooking tray 14 is positioned in the second recording plane E2 and is in its extended position (see Figure 1b). The configuration of the second freeform lens 28a and the second light source 222 corresponds essentially to the configuration shown in Figure 2a, except for the design of the freeform surface 30a. The freeform surfaces 30, 30a are non-rotationally symmetrical and not planar, and are only simplified to represent a smooth surface. Each freeform surface 30, 30a can, for example, be manufactured according to a surface design specifically developed using computer-aided numerical methods for the optimal illumination of the cooking tray 14 in the respective recording plane E1 or E2.Each of the freeform lenses 30, 30a can have a plurality of segments that are alternately convex and concave along the depth direction T and / or the width direction R. Each.
[0045] The light source 221, 222 is designed to direct light rays exclusively onto their respective freeform lenses 28, 28a. For this purpose, the lighting device 20 has an opaque partition 24 arranged between the freeform lenses 28, 28a. For clarity, the partition 24 is indicated by an area bounded by a dashed line. The freeform lenses 28, 28a are arranged together on the transparent carrier plate 26, which ensures stable and precise alignment of the freeform lenses 28, 28a. The freeform lenses 28, 28a can be attached to the carrier plate 26 or formed integrally with it. Figure 2c shows the first freeform lens 28 in a frontal detail view. For clarity, only the first optical axis A of the light source is shown.The carrier plate 26 forms a flat light-emitting surface 34 of the lighting device 20, which is associated with the first free-form lens 28. Light radiation can emerge from the lighting device 20 at the light-emitting surface 34 to illuminate the cooking carrier surface 140 of the cooking carrier 14, which is received and extended in the first recording plane E1.
[0046] Preferably, each of the freeform lenses 28, 28a is associated with such a light-emitting surface 34. If several freeform lenses 28, 28a are arranged side by side along the lateral direction B, as shown in Figure 2b, the light cones or light pyramids 23, 23a emitted by the freeform lenses 28, 28a are also offset from each other in the lateral direction B. To counteract this offset, the light-emitting surfaces 34 can be inclined at an angle β of between 1° and 10° relative to the recording planes E1, E2 or to the horizontal line L. In Figure 2c, i.e., viewed from a perspective in the depth direction T, the light-emitting surface 34 associated with the first freeform lens 28 is inclined at an angle β of 3° counterclockwise relative to the recording planes E1, E2 or to the horizontal line L.An exemplary light beam S emitted by the first light source 221 is thus refracted at the inclined light emission surface 34, thereby compensating for a lateral offset of the light cone or light pyramid. Preferably, the light emission surfaces 34 of different freeform lenses 28, 28a are inclined relative to the recording planes E1, E2 by different angles of inclination β and / or by different directions of inclination in order to compensate for the respective offset.
[0047] In principle, the number of freeform lenses can be adjusted to the number of recording planes present in the receiving system 12 of the cooking appliance 2. Figures 3 and 4 each show a top view of the cooking carrier 14 illuminated by the lighting device 20. The features of the respective freeform lens 28, 28a described below refer to a lens in the respective assigned
[0048] Recording level E1, E2 recorded cooking carrier 14.
[0049] Figure 3 shows isolines 32, 32a of a light distribution of the lighting device 20 with and without freeform lenses 28, 28a. For the purposes of this invention, isolines 32, 32a are understood to be lines on the cooking carrier surface 140 on which the same light intensity value occurs at every point. Since the light sources 221, 222 of the light source 22 have a radiation pattern in which the intensity of the radiation is maximum along the optical axis A, A' and decreases with increasing beam angle to the optical axis A, A', the isolines 32a of the light distribution exhibited by the light source 22 itself run essentially circularly around a center M of the cooking carrier surface 140. To achieve optimal illumination of the cooking carrier 14, the
[0050] Freeform lenses 28, 28a are configured to compress isolines 32 of the light distribution relative to isolines 32a of the light distribution exhibited by the light source 22 itself in sections 321 facing the center of one of the sides 141 towards the center M of the light distribution and / or to stretch them towards the corners 142 in sections 322 facing the corners 142. In this way, the round cross-sectional contour of the light distribution exhibited by the light source 22 itself can be increasingly transformed, at least section by section, into straight lines and adapted to the rectangular shape of the cooking carrier surface 140.
[0051] Figure 4 shows designated areas of the cooking carrier surface 140, each with defined light intensity limits. For the illumination of the cooking carrier 14, it has proven advantageous if the freeform lenses 28, 28a are designed to illuminate the cooking carrier surface 140 of the fully extended cooking carrier 14 in such a way that the light intensity in a centrally located inner area 143 of the cooking carrier surface 140, which comprises at least 50% of the cooking carrier surface 140, corresponds to between 80% and 100% of the maximum light intensity of the light distribution.Particularly advantageous illumination of the cooking carrier can be achieved if the freeform lenses 28, 28a are designed to illuminate the cooking carrier surface 140 of the fully extended cooking carrier 14 such that the light intensity in a centrally located area 144 of the cooking carrier surface 140, which comprises at least 30% of the cooking carrier surface 140, corresponds to between 90% and 100% of the maximum light intensity of the light distribution. The inner area 143 and / or central area 144 can each have a rectangular shape and must be evenly spaced from the sides 141 of the cooking carrier surface 140.
[0052] To counteract the formation of light reflections that could impair the aesthetic appearance of the cooking appliance 2 and the kitchen or dazzle a user, it is advantageous to reduce the amount of light emitted past the cooking carrier 14. Preferably, the freeform lenses 28, 28a are therefore designed to emit, when the cooking carrier 14 is fully extended, only a maximum of 30%, preferably a maximum of 10%, of the total light intensity emitted by the lighting device 20 away from the surface 140 of the cooking carrier 14. Particularly preferably, the freeform lenses 28, 28a are designed to emit, when the cooking carrier 14 is fully extended, the entire light intensity emitted by the lighting device 20 onto the surface 140 of the cooking carrier 14.Figure 5 shows a graphical comparison of the light distribution of the lighting device 20 on a rectangular, flat surface, both without and with freeform lenses 28, 28a. The two figures are based on computer simulations. The figure on the left shows a light distribution produced by the light emitted from the light source 22, which is then directed through a flat viewing window onto the flat surface. The isolines 32a are recognizably rounded and run concentrically to each other with a substantially constant radial spacing. The shape of the isolines 32a, and in particular the outer contour of the light distribution, does not correspond to the rectangular surface. Deviations from a rotationally symmetrical shape are due to the inclination of the optical axes A, A' to the flat surface.The figure on the right shows a light distribution produced by the light emitted from the light source 22, which is then directed onto the flat surface by a freeform lens 28, 28a of the type described above. The figure on the right thus shows a light distribution such as can be achieved with a cooking appliance 2 according to the invention. By using the freeform lens 28, the shape of the isolines 32 has been closely approximated to the rectangular shape of the flat surface. At the same time, the isolines 32 have been shifted towards the edges of the flat surface, so that an almost identical light intensity is provided in a relatively large central area.
Claims
Patent claims 1. Cooking appliance (2) with a cooking chamber (10) bounded by cooking chamber walls and closable by means of a cooking chamber door (8), a receiving system (12) arranged in the cooking chamber (10) for receiving a food carrier (14) in one of several receiving levels (E1, E2) and a lighting device (20) which has a light source (22) and is designed to illuminate the cooking carrier (14) which is received in the receiving system (12) and at least partially extended from the cooking chamber (10), characterized in that Each of the multiple recording planes (E1, E2) is assigned a freeform lens (28, 28a) of the illumination device (20), wherein each of the freeform lenses (28, 28a) has at least one freeform surface (30, 30a) and is designed to direct light radiation emitted by the light source (22) by refraction onto a cooking carrier surface (140) of the cooking carrier (14) received and extended in the respective associated recording plane (E1, E2), wherein the light-emitting surface on the cooking carrier surface coincides approximately with the geometric boundaries of the cooking carrier.
2. Cooking appliance (2) according to claim 1, characterized in that the cooking appliance (2) has a detection device (50) which is configured to detect in which of the several receiving planes (E1, E2) the food carrier (14) which has been at least partially removed from the cooking chamber (10) is received, and has a control device (40) which is configured to control the lighting device (20) in such a way that the light radiation emitted by the light source (22) is guided through the free-form lens (28, 28a) associated with the detected receiving plane (E1, E2) and directed onto the surface (140) of the food carrier (14).
3. Cooking appliance (2) according to claim 2, characterized in that the detection device (50) has at least one sensor (51, 51a) configured to detect in which of the several receiving planes (E1, E2) the food carrier (14), which has been at least partially removed from the cooking chamber (10), is received.
4. Cooking appliance (2) according to any one of claims 1 to 3, characterized in that each of the freeform lenses (E1, E2) is assigned a light source (221, 222) of the light source (22), wherein each light source (221, 222) is configured to direct light rays exclusively onto the respective assigned freeform lens (28, 28a).
5. Cooking appliance (2) according to one of claims 1 to 4, characterized in that the freeform lenses (28, 28a) are arranged next to each other along a horizontal line (L).
6. Cooking device (2) according to one of claims 1 to 5, characterized in that the freeform lenses (28, 28a) are arranged together on a transparent carrier plate (26).
7. Cooking device (2) according to one of claims 1 to 6, characterized in that each of the freeform lenses (28, 28a) is assigned a light emission surface (34) of the lighting device (20) facing away from the light source (22) and which is flat, from which light radiation can emerge from the lighting device (20) in order to illuminate the cooking carrier surface (140) of the cooking carrier (14) received and extended in the respective receiving plane (E1, E2).
8. Cooking appliance (2) according to claim 7, characterized in that at least one of the light emission surfaces (34) is inclined relative to the receiving planes (E1 , E2) by an angle of inclination (β) between 1° and 10°.
9. Cooking appliance (2) according to claim 8, characterized in that at least two of the light emission surfaces (34) are inclined relative to the receiving planes (E1, E2) by different angles of inclination (β) and / or by different directions of inclination.
10. Cooking appliance (2) according to one of claims 1 to 9, wherein the freeform lenses (28, 28a), in particular the freeform surfaces (30, 30a) of the respective freeform lenses (28, 28a), differ with respect to geometry and emission characteristics.
11. Cooking appliance (2) according to one of claims 1 to 10, characterized in that the lighting device (20) has at least one opaque partition (24) arranged between two of the freeform lenses (28, 28a).