Cooking appliance having an illumination device comprising a free-form lens

Abstract

The invention relates to a cooking appliance (2) having a cooking chamber (10), a receiving system (12) for receiving a cooking product support (14) on at least one receiving level (E) of the receiving system (12), and an illumination device (20) designed to illuminate the cooking product support (14) that is received on the receiving level (E) of the receiving system (12) and at least partially pulled out of the cooking chamber (10). According to the invention, the illumination device (20) is equipped with a free-form lens (28) which is designed to direct light radiation emitted by the light source (22) onto a cooking product support surface (140) of the pulled-out cooking product support (14) by refraction.

Description

[0001] Description

[0002] Cooking appliance with a lighting device featuring a free-form lens

[0003] The invention relates to a cooking appliance with a cooking chamber bounded by cooking chamber walls and closable by means of a cooking chamber door, a receiving system for receiving a food carrier in the cooking chamber in at least one receiving plane of the receiving system for the food carrier and a lighting device which has at least one light source and is designed to illuminate the food carrier which is received in the receiving plane of the receiving system and is at least partially extended from the cooking chamber.

[0004] Such lighting devices can also be referred to as anteroom lighting. Typically, light sources, such as LEDs, are used that 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 thus 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 light cone is too small, this leads to shadows and insufficient visibility of certain areas of the cooking tray.If the light cone is too large, some of the light will be directed past the cooking carrier, causing light reflections that impair the aesthetic appearance of the cooking appliance and the kitchen and can dazzle a user.

[0005] To improve light distribution on the cooking tray surface, it is known, for example, to influence the direction or opening angle of the emitted light cone using prisms or spherical lenses. However, such solutions are not able to sufficiently reduce the disadvantages described above.

[0006] 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.

[0007] According to the invention, this problem is solved by a cooking device with the features of claim 1. Advantageous embodiments and further developments of the invention are set forth in the following dependent claims. The cooking device according to the invention is characterized in that the lighting device has a freeform lens with at least one freeform surface, wherein the freeform lens is configured to direct light radiation emitted by the light source onto a cooking carrier surface of the extended cooking carrier by means of light refraction.

[0008] The advantage achievable with the invention lies in the fact that the use of a freeform lens allows for a high degree of freedom in designing the light distribution. In particular, the light cone can be optimally adapted to the shape of the cooking tray to ensure ideal illumination. Furthermore, the freeform lens requires little installation space and can be easily integrated into the cooking appliance. Moreover, in many cases, excellent illumination of the cooking tray in a given imaging plane can be achieved with just one light source and one freeform lens.

[0009] In a freeform lens, as in any other lens, light is directed by refraction at the 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). 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.

[0010] A preferred embodiment of the cooking device according to the invention provides that the free-form lens is designed to approximate the shape of the cooking carrier surface of the extended cooking carrier by means of light refraction. This approximates the light distribution of the lighting device, in contrast to the light distribution exhibited by the light source 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 lens is 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 illuminance occurs at every point.

[0011] The term illuminance can also be synonymous with the term light intensity or the term light intensity value.

[0012] By compressing the isolines, the curves of the light source's light distribution are increasingly transformed into straight lines and adapted to the rectangular shape of the cooking tray. Alternatively or additionally, the curves of the light source's light distribution can be stretched outwards in sections facing the corners of the cooking tray, so that they approximate the tray's rectangular shape.

[0013] In particular, the cross-sectional contour of the light cone refracted in this way by the freeform lens and striking the surface of the food carrier can be described, at least section by section, by a superellipse or hyperellipse.

[0014] Another preferred embodiment of the cooking device according to the invention provides that the freeform lens is designed to illuminate the surface of the fully extended food carrier such that the illuminance in a centrally located inner area of ​​the food carrier surface, comprising at least 50% of the surface area, corresponds to between 80% and 100% of the maximum illuminance of the light distribution. In particular, the centrally located inner area 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 illuminance, thereby improving the visibility of the food carrier surface in an aesthetically pleasing manner. The fully extended position of the food carrier is determined by the receiving system used.In this position, the cooking tray can be completely extended out of the cooking chamber or still protrude partially into the cooking chamber.

[0015] A further preferred embodiment of the cooking device according to the invention provides that the free-form lens is designed to illuminate the surface of the fully extended food carrier such that the illuminance 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 illuminance 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 ensures that a substantial portion of the food carrier surface is illuminated with a nearly uniform illuminance, thereby further improving the visibility of the food carrier surface.

[0016] Another preferred embodiment of the cooking device according to the invention provides that the freeform lens is designed to emit a maximum of 30%, preferably a maximum of 10%, of the total illuminance emitted by the lighting device away from the surface of the cooking carrier when the cooking tray is fully extended. 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 lens is designed to emit the entire illuminance emitted by the lighting device onto the surface of the cooking carrier when the cooking tray is fully extended. In other words, no light is bypassed by the cooking carrier.

[0017] Another preferred embodiment of the cooking device according to the invention provides that the freeform surface of the freeform lens faces the light source. In this way, the light refraction occurs closer to the light source, allowing the freeform lens to capture more light. Furthermore, the lighting device can be designed more compactly.

[0018] Another preferred embodiment of the cooking device according to the invention provides that a rear surface of the freeform lens, opposite the freeform surface of the freeform lens, is flat. This simplifies the manufacturing of the freeform lens. Furthermore, the rear surface can serve as the exit surface of the lighting device, which is easy to clean due to its smooth surface. Preferably, the flat rear surface of the freeform lens is 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. This allows for a compact design of the lighting device, ensuring efficient illumination of the cooking device's anteroom and enabling easy integration into the control panel of the cooking device.

[0019] In particular, the flat rear surface of the freeform lens extends parallel to the recording plane of the recording system.

[0020] An embodiment of the invention is shown purely schematically in the drawings and is described in more detail below. It shows

[0021] Figure 1 shows an embodiment of a cooking appliance according to the invention in a partial side view;

[0022] Figure 2 shows the lighting device of the cooking appliance from Figure 1 in a detailed view; Figure 3 shows the cooking carrier of the cooking appliance from Figure 1 illuminated according to an embodiment of the invention in a top view;

[0023] Figure 4 shows the cooking tray of the cooking appliance from Figure 1 illuminated according to a further embodiment of the invention in a top view; and Figure 5 shows a graphical comparison of the light distribution of the lighting device on a rectangular surface, both without and with a free-form lens.

[0024] Figure 1 shows 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. The cooking appliance 2 has a receiving system 12 with at least one receiving plane E extending parallel to the horizontal direction B and the vertical direction T, in which a food carrier 14 can be received in the cooking chamber 10. For receiving the food carrier 14 in the receiving plane E, the receiving system 12 has, for example, a telescopic extension 16 (see Figures 3 and 4). The telescopic extension 16 can be designed as a partial extension, a full extension, or an overextension.The cooking appliance 2 further comprises a lighting device 20, which includes at least one light source 22 and is designed to illuminate the food carrier 14, which is at least partially extended from the cooking chamber 10 and is received in the receiving plane E of the receiving system 12. 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.

[0025] To ensure optimal illumination of the rectangular cooking tray 14, the lighting device 20 has a freeform lens 28 with at least one freeform surface 30 (see Figure 2). The freeform lens 28 is designed to direct the light radiation emitted by the light source 22 onto a cooking tray surface 140 of the extended cooking tray 14 by means of light refraction. By refraction of the light radiation emitted by the light source 22 at the freeform surface 30, the light distribution of the lighting device 20 can be approximated to the rectangular shape of the cooking tray surface 140 of the extended cooking tray 14, compared to the light distribution exhibited by the light source 22 itself.

[0026] Figure 2 shows a detailed view of the lighting device 20 of the cooking appliance 2. The light source 22 is, for example, an LED. The freeform surface 30 of the freeform lens 28 faces the light source 22. 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 34 of the freeform lens 28, opposite the freeform surface 30 of the freeform lens 28, forms a light emission surface of the lighting device 20 facing the extended cooking tray 14 and is flat. The rear surface 34 can thus be easily cleaned. The flat rear surface 34 of the freeform lens 28 can extend parallel to the recording plane E.For the compactness of the lighting device 20, it has proven advantageous if the flat rear surface 34 of the freeform lens 28 is oriented at an angle α between 20° and 80°, preferably at an angle between 40° and 60°, to the optical axis A of the light source 22. Figures 3 and 4 each show the cooking tray 14 illuminated by the lighting device 20 in a top view.

[0027] Figure 3 shows isolines 32, 32a of a light distribution of the lighting device 20 with and without a freeform lens 28. For the purposes of this invention, isolines 32, 32a are understood to be lines on the cooking carrier surface 140 on which the same illuminance occurs at every point. Since the light source 22 has a radiation pattern in which the intensity of the radiation is maximum along the optical axis A and decreases with increasing beam angle to the optical axis, 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 tray 14, the freeform lens 28 is designed 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 in sections, into straight lines and adapted to the rectangular shape of the cooking tray surface 140.

[0028] Figure 4 shows designated areas of the cooking carrier surface 140, each with defined illuminance limits. For the illumination of the cooking carrier 14, it has proven advantageous if the freeform lens 28 is designed to illuminate the cooking carrier surface 140 of the fully extended cooking carrier 14 in such a way that the illuminance 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 illuminance of the light distribution.Particularly advantageous illumination of the cooking tray can be achieved if the freeform lens 28 is designed to illuminate the cooking tray surface 140 of the fully extended cooking tray 14 in such a way that the illuminance in a centrally located area 144 of the cooking tray surface 140, which comprises at least 30% of the cooking tray surface 140, corresponds to between 90% and 100% of the maximum illuminance of the light distribution. Interior area 143 and / or.

[0029] The central area 144 can each have a rectangular shape and is evenly spaced to the sides 141 of the cooking carrier surface 140.

[0030] 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 lens 28 is therefore designed to emit only a maximum of 30%, preferably a maximum of 10%, of the total illuminance emitted by the lighting device 20 away from the cooking carrier surface 140 of the cooking carrier 14 when the cooking carrier 14 is fully extended. Particularly preferably, the freeform lens 28 is designed to emit the entire illuminance emitted by the lighting device 20 onto the cooking carrier surface 140 of the cooking carrier 14 when the cooking carrier 14 is fully extended.

[0031] Figure 5 shows a graphical comparison of the light distribution of the lighting device 20 on a rectangular, flat surface, both with and without the freeform lens 28. 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 axis 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 free-form lens 28 of the type described above. The figure on the left thus shows a light distribution such as can be achieved with a cooking appliance 2 according to the invention. By using the free-form 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 illuminance is provided in a relatively large central area.

Claims

9 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) for receiving a food carrier (14) in the cooking chamber (10) in at least one receiving plane (E) of the receiving system (12) for the food carrier (14) and a lighting device (20) which has at least one light source (22) and is designed to illuminate the food carrier (14) which is received in the receiving plane (E) of the receiving system (12) and is at least partially extended from the cooking chamber (10), characterized in that the lighting device (20) has a free-form lens (28) with at least one free-form surface (30), wherein the free-form lens (28) is designed to direct light radiation emitted by the light source (22) onto a food carrier surface (140) of the extended food carrier (14) by refraction.

2. Cooking device (2) according to claim 1, characterized in that the freeform lens (28) is designed to approximate the light distribution of the lighting device (20) to the shape of the cooking carrier surface (140) of the extended cooking carrier (14) by refraction of light.

3. Cooking device (2) according to claim 2, characterized in that the cooking carrier surface (140) has a rectangular shape with four sides (141) and four optionally rounded corners (142), wherein the freeform lens (28) is designed to compress isolines (32) of the light distribution towards a center (M) of the light distribution in sections (321) facing a center of one of the sides (141) and / or to stretch them towards the corners (142) in sections (322) facing the corners (142).

4. Cooking device (2) according to one of claims 1 to 3, characterized in that the freeform lens (28) is designed to illuminate the cooking carrier surface (140) of the fully extended cooking carrier (14) in such a way that the illuminance in a centrally located inner area (143) of the cooking carrier surface (140), which makes up at least 50% of the cooking carrier surface (140), corresponds to between 80% and 100% of the maximum illuminance of the light distribution.

5. Cooking device (2) according to one of claims 1 to 4, characterized in that the freeform lens (28) is designed to illuminate the cooking carrier surface (140) of the fully extended cooking carrier (14) in such a way that the illuminance in a centrally located central area (144) of the cooking carrier surface (140), which makes up at least 30% of the cooking carrier surface (140), corresponds to between 90% and 100% of the maximum illuminance of the light distribution.

6. Cooking device (2) according to one of claims 1 to 5, characterized in that the freeform lens (28) is designed to emit a maximum of 30%, preferably a maximum of 10%, of the total illuminance emitted by the lighting device (20) away from the surface (140) of the cooking carrier (14) when the cooking carrier (14) is fully extended.

7. Cooking device (2) according to claim 6, characterized in that the freeform lens (28) is designed to emit the entire illuminance emitted by the lighting device (20) onto the cooking carrier surface (140) of the cooking carrier (14) when the cooking carrier (14) is fully extended.

8. Cooking appliance (2) according to one of claims 1 to 7, characterized in that the freeform surface (30) of the freeform lens (28) faces the light source (22).

9. Cooking appliance (2) according to one of claims 1 to 8, characterized in that a rear surface (34) of the freeform lens (28) opposite the freeform surface (30) of the freeform lens (28) is flat.

10. Cooking appliance (2) according to claim 9, characterized in that the flat rear surface (34) of the freeform lens (28) is oriented at an angle (a) between 20° and 80°, preferably at an angle between 40° and 60°, to the optical axis (A) of the light source (22).

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