Display device for an electrical appliance, electrical appliance having such a display device, and method for producing a display device

Abstract

A display device for an electrical appliance has a light-permeable display screen and a flat mask with an upper face and a lower face underneath, wherein the flat mask is basically opaque and has, in the opaque surface thereof, light passages in the form of light indicators to be displayed luminously. The display device also has a flat spacer with an upper face and a lower face, the spacer having light channels which pass through the spacer and coincide with the light passages in the mask and are arranged correspondingly thereto. Lighting means are provided below the spacer and in the light channels thereof. The spacer has a matte, black, or non-reflective surface on the spacer upper face pointing towards the mask, and / or the mask has a matte, black, or non-reflective surface on the mask lower face pointing towards the spacer.

Description

[0001] Display device for an electrical appliance, electrical appliance with such a display device and method for manufacturing a display device

[0002] SCOPE OF APPLICATION AND STATE OF THE ART

[0003] The invention relates to a display device for an electrical appliance, an electrical appliance equipped with such a display device, and a method for manufacturing such a display device.

[0004] Display devices for electrical appliances such as cooktops are known in the prior art; see, for example, EP 3 121 965 B1 or DE 10326684 A1. In these devices, an LED indicator is positioned behind a cooktop element as a display panel. To ensure a sharp, clear display visible from above, a mask with corresponding light passages or cutouts is provided below the cooktop element.

[0005] TASK AND SOLUTION

[0006] The invention is based on the objective of providing a display device for an electrical appliance as mentioned above, an electrical appliance equipped with such a display device, and a method for manufacturing such a display device, with which problems of the prior art can be solved and, in particular, it is possible to manufacture a display device with low effort and high quality of the light display, as well as to create an electrical appliance that has the best possible light display.

[0007] This problem is solved by a display device with the features of claim 1, by an electrical device with the features of claim 11, and by a method for manufacturing a aforementioned display device with the features of claim 13. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features are described only for the display device, only for the electrical device, or only for the manufacturing method. However, they should be able to apply independently and autonomously to such a display device, such an electrical device, and such a manufacturing method. The wording of the claims is made part of the description by express reference. The display device has a planar display panel, advantageously flat or planar and extended.The display panel is at least partially translucent or consists of a translucent material, which is advantageously not completely transparent but colored. Furthermore, the display device has a flat mask, the mask having a top and a bottom. The mask is arranged below the display panel, advantageously attached to or pressed against its underside. The flat mask is generally opaque, either by coating or by using a suitable material, and light passages are provided in its opaque area. These light passages are in the form of illuminated displays, which are intended to be seen by an operator. These light passages, and thus the illuminated displays, can be numbers, letters, symbols, pictograms, or the like. A flat, extended orA specially designed spacer is provided, which also has a top and a bottom. It features light channels running through it, from the top to the bottom. These light channels should correspond to the light apertures of the mask and be arranged accordingly. Advantageously, they are positioned directly above one another and are exactly the same size. Light sources, preferably LEDs, are arranged below the spacer, and can be positioned in or below the light channels. This allows them to shine through the channels and thus through the spacer, through the mask above the spacer, and upwards through the display aperture. In this way, they are visible as an illuminated display. Therefore, in addition to the mask with its light apertures, the spacer with its light channels also serves to create the precise shape and type of illuminated display.

[0008] According to the invention, in a first embodiment, the spacer has a matte or black or non-reflective surface on its upper surface. This upper surface faces the mask and may even be in contact with the underside of the mask. Alternatively, in a second embodiment, the mask can have the aforementioned matte or black or non-reflective surface on its underside, which also faces or is in contact with the spacer. In essence, the invention provides the aforementioned surface, coating, or layer, which is matte, black, or non-reflective, between the upper surface of the spacer and the mask or its underside.This surface with these properties has the advantage that scattered or reflected light, which passes from the aforementioned light sources through the spacer's light channels and the mask's light apertures, is not reflected laterally due to reflections from the top of the spacer or the underside of the mask. This allows the light to spread laterally through multiple reflections and then shine upwards through adjacent light apertures in the mask. From an external perspective, this would create the effect of light shining not only through one aperture as intended, but also through an adjacent one. This would result in an unsightly and, in the worst case, indistinct or even undetectable light pattern. This should be avoided whenever possible.

[0009] The matte, black, or non-reflective surface on the top of the spacer is advantageous. This ensures that its exposed surface, i.e., the top of the spacer, faces the underside of the mask, maximizing its non-reflective properties. This prevents light from being coupled into or reflected into the mask outside the light apertures due to reflection off this surface. However, the underside of the mask is also suitable for this coating to prevent reflections. This offers production advantages, as the spacer then does not need to be coated or processed.

[0010] In one embodiment of the invention, the display device has a component carrier which is arranged on the underside of the spacer or on which the spacer rests with its underside. This component carrier is advantageously a printed circuit board. At least the aforementioned light sources can be arranged on it and electrically connected, advantageously in the form of LEDs, and particularly advantageously in the form of soldered SMD LEDs.

[0011] In a further embodiment of the invention, the mask itself can be made of translucent material, advantageously transparent material. A somewhat thicker plastic film, for example made of polyethylene or PET material, is suitable for this purpose. To achieve the aforementioned properties of opacity, an opaque cover layer can be provided on at least one side, preferably on the top side facing the display aperture. This cover layer can be applied as a coating, for example with paint, or alternatively as a film or adhesive. Advantageously, the cover layer can first be applied to the entire surface of the top side of the mask, for example as a suitable coating or paint. It can then be removed in the desired shape to create the aforementioned light transmission or in the shape required for the desired illuminated display.This removal can be done mechanically, or alternatively and preferably by means of a laser. This is known in the prior art. This makes it possible to produce masks or display devices in small quantities with individual customization, since reprogramming a laser to remove the coating is relatively straightforward. In an embodiment of the invention, the mask can be relatively thin compared to the display aperture and / or the spacer. Its thickness can be less than 2 mm, advantageously between 0.05 mm and 0.5 mm. This is sufficient to create a sufficiently sharp edge for the illuminated display with a suitable opaque coating or the like, advantageously as the aforementioned cover layer. Furthermore, this allows the overall height of the display device below the display aperture to be kept as low as possible, thus saving installation space.

[0012] In a further development of the invention, the spacer can be at least as large as the mask, preferably having a corresponding shape. This can be such that the mask does not project beyond the spacer on any outer surface. The spacer can extend as far as the mask on each outer surface or along its outer contour, or even project beyond it. It can be advantageous to provide that the mask is attached to the spacer, so that both together form a single unit. Adhesive bonding is suitable for this purpose, as are clamping or fastening by means of plastic welding or similar methods. If this is carried out automatically in a method according to the invention for manufacturing the display device, it can be done very precisely, so that the desired alignment of the light transmission of the mask with the light channels in the spacer is achieved as closely as possible.

[0013] The LEDs mentioned can be arranged within the light channels, so that the spacer's underside rests directly on the top of the component carrier. The light sources or LEDs mounted on the component carrier then protrude into these light channels.

[0014] In this embodiment of the invention, the spacer consists of an opaque material, advantageously plastic. A colored plastic, such as white, is particularly advantageous. This allows light to be reflected in the walls of the light channels within the spacer and then shine upwards through the light apertures in the mask as part of the illuminated display. This increases the luminous efficacy. For this purpose, the walls of the light channels can also be glossy or highly reflective. Preferably, however, the material from which the spacer is manufactured is different from the material used in the invention to create the non-reflective surface.

[0015] In a further development of the invention, the aforementioned non-reflective surface can be created by coating either the top surface of the spacer and / or the underside of the mask with a black coating, preferably as deep black as possible. This coating should have a matte black surface, i.e., be as non-reflective as possible. This surface should therefore be made of a different material than the spacer and the mask, which can be made of a transparent material. It can thus be a separate material altogether. The thickness of this coating should be less than 1 mm, advantageously being between 0.02 mm and 0.5 mm. This is certainly sufficient to prevent light from passing through it at the luminance levels expected for display devices in electronic equipment. Ultimately, it is the surface properties that are crucial.

[0016] As an alternative to the aforementioned coating, which achieves the matte black surface, the top surface of the spacer and / or the underside of the mask can be roughened, for which subsequent processing such as sanding or etching is suitable. Thus, no additional material with the desired surface properties is applied; rather, the surface of the material itself, i.e., the spacer or the mask, is treated so that it becomes non-reflective or loses any reflective properties.

[0017] In a further development of the invention, it can be provided that the underside of the mask, which faces the spacer, has no coating and is untreated. In this case, the top surface of the spacer forms or has the non-reflective surface. This underside of the mask is then simply exposed or formed from the mask material itself.

[0018] In this embodiment of the invention, the light channels of the spacer are designed as openings, meaning they are empty or contain no material. This ensures maximum light transmission while simultaneously saving material and creating more installation space for the aforementioned light sources.

[0019] In an electrical appliance according to the invention with a display device as described above, the display device or its display panel can be integrated into an outer surface of the electrical appliance, be part of this outer surface, or form the entire outer surface of the electrical appliance. This allows for a simple and practical design of the electrical appliance. An example of such an electrical appliance is a cooktop that has a continuous, full-surface glass-ceramic cooktop surface. This glass-ceramic cooktop surface forms the display panel, and the mask is pressed onto its underside. This mask rests on the spacer, which in turn rests on the component carrier. Heating elements of the cooktop, as are generally known from the prior art, can be arranged laterally next to the mask and spacer.Other possibilities for an electrical appliance according to the invention include ovens, microwave ovens, washing machines and tumble dryers, as well as dishwashers. These also have displays and display panels, as is known.

[0020] These and other features are evident not only from the claims but also from the description and the drawings, whereby the individual features, either alone or in combination, may be implemented in one embodiment of the invention and in other fields, and may represent advantageous and individually protectable embodiments for which protection is claimed here. The division of the application into individual sections and subheadings does not limit the general validity of the statements made therein.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Exemplary embodiments of the invention are shown schematically in the drawings and are explained in more detail below. The drawings show:

[0023] Fig. 1 shows a simplified sectional view through a cooktop as an electrical appliance according to the invention, comprising a heating device and a display device according to the invention.

[0024] Fig. 2 shows a display representation of a seven-segment display as a display device with differently illuminated segments,

[0025] Fig. 3 shows a display device according to the prior art without the matte black surface according to the invention on the underside of the mask,

[0026] Fig. 4 shows an exploded sectional view through a display device according to the invention on the hob from Fig. 1 with hob plate as display panel, mask and spacer on a circuit board and

[0027] Fig. 5 shows the display device from Fig. 3 in its assembled state.

[0028] DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES

[0029] Figure 1 shows a cross-sectional view of a portion of a cooktop 11 according to the invention, comprising a cooktop surface 12 with a top surface 13 and a bottom surface 14. On the left side of Figure 1, a heating element 16 is positioned beneath the cooktop surface 12, specifically pressed against its underside 14. To the right of this, a display device 18 according to the invention is pressed against the underside 14. The heating element 16 can be a radiant heating element or, advantageously, an induction heating coil. The cooktop surface 12 is a glass-ceramic plate, advantageously a single, continuous piece, which, in a known manner, forms the surface on which a cooking vessel can be placed above the heating element 16 for heating or cooking. Furthermore, the cooktop surface 12 also forms a display panel for the display device 18 according to the invention, thus covering and protecting it.The display device 18 or adjacent to it also has operating elements, such as advantageously capacitive or optical controls, as is known for cooktops. These are operated by placing a finger above them. However, operating the cooktop 11 during its cooking operation is not relevant here.

[0030] Figure 2 shows a seven-segment display 21 as an illuminated display 20. The seven-segment display 21 has seven segments 23 arranged as a bar, a concept that is generally known. The two vertical left segments 23 are unilluminated. The other segments 23 are illuminated, as indicated by the hatching, possibly with a specific color, for example, red. These colors are then not only visible on the display device 18 or on the seven-segment display 21 itself, but also through the cooktop 12. They should be displayed as precisely and with as sharp a contour as possible. Overexposure from one segment 23 to an adjacent segment 23 should be prevented.

[0031] A seven-segment display according to the prior art is shown in Fig. 3. Here, an LED is positioned at the very bottom of a printed circuit board (PCB) LP, specifically within a light channel LK of a spacer AH resting on the PCB LP. A mask M rests on the spacer AH and is adhered to it with a transparent adhesive layer K on its underside. The mask M has a conductive layer L on its upper side, which is electrically conductive and designed in specific structures according to the prior art to form capacitive touch switches as the aforementioned operating elements.

[0032] A diffuser layer D, advantageously formed by a film, is arranged on the conductive layer L. This layer can be light-transmitting but translucent to ensure uniform illumination and thus a uniform light display. A cover layer A is located on the diffuser layer D. It consists of light and a thin, transparent coating material, which is removed as desired, for example, as shown in Fig. 2 with the individual segments. This cover layer A is used to press the light display onto the underside of the cooktop panel GK. Fig. 3 shows how light could be reflected from the LED at the underside of the mask M according to the dotted line, so that it shines downwards again through the transparent adhesive layer K. It could then be reflected upwards again at the top of the spacer AH, and then either exit upwards or be reflected downwards once more.With each reflection, the light beam will travel further in a lateral direction and could then spread laterally within the mask M, so that it could emerge upwards at another free point in the cover layer A. Referring to Fig. 2, this could lead to a situation where, even next to or adjacent to a segment 23 that is to be illuminated, a segment that is not intended to be illuminated would still be illuminated and visible from above. This would negatively impair the clarity and distinctness of the indicator light 20. The invention prevents this; no reflection can form at an interface between the underside of the mask 26 and the top side of the spacer 40.

[0033] Figure 4 shows the display device 18 according to the invention in a sectional view. A gap is shown between the underside 14 of the cooktop plate 12 and a mask 26, which does not exist in practice; see also Figure 5. The mask 26 is a plastic film approximately half a millimeter thick; it is actually transparent or consists of completely transparent material. A cover layer 28 is provided on its upper surface, which has been removed in a cutout 29. The cutout 29 corresponds in shape exactly to a desired segment 23 as shown in Figure 2. Otherwise, the cover layer is opaque and advantageously black. It can be designed to cover or coat the entire mask 26 made of film material. For the seven-segment display 21, three such segments 23 have been removed or laser-cut from the cover layer 28.Light from a light source positioned below can shine through here and form the illuminated indicator 20 in this area. Such cover layers, as well as methods for processing or removing them, are generally known in the prior art.

[0034] A diffuser layer 31 is provided below the cover layer 28. It consists of a translucent material that evens out the transmitted light. The diffuser layer 31 can be applied to the mask 26 as a liquid or paste-like coating and then harden there. Alternatively, it can be a separate film that is placed on the mask 26, for example, by gluing it in place.

[0035] Below the diffuser layer 31, or directly on the top surface of the mask 26, a layer is provided in which electrically conductive areas are included. Unlike the cover layer 28 and the diffuser layer 31, this conductive layer 33 is not provided across the entire surface or largely across the entire surface, but only in relatively limited areas. Reference is made, for example, to DE 102008018450 A1. The aforementioned touch switches, as well as their connecting wires, can be designed as capacitive operating elements using fields made from this conductive layer 33.

[0036] Directly on the underside of the mask 26, a lower cover layer 35 is provided, which is advantageously made of the same material as the upper cover layer 28. It can have the same cutout 36 as the upper cutout 29, advantageously with the same shape and exactly vertically above it. The cutout 36 is also advantageously manufactured in the same way as the cutout 29.

[0037] Below the lower cover layer 35, an adhesive layer 38 is applied, advantageously made of transparent and translucent adhesive. It can be provided with a removable protective film so that, when the entire cooktop 11 or at least the display device 18 is mounted, the mask 26 can be adhered to a spacer 40. While the mask 26 itself, including the layer structure on the top and bottom, should be less than 2 mm thick, the spacer 40 can have a thickness or height of 3 mm to 10 mm.

[0038] The spacer 40 has a light channel 41, shown with a dashed line, which is located exactly vertically below the cutouts 29 and 36 on the mask 26. This light channel 41 contains no material from the spacer 40; the spacer 40 has a closed surface around the top of the light channel 41.

[0039] The spacer 40 is made of opaque plastic, preferably white plastic. It is placed directly onto a circuit board 44, preferably also attached to it, for example by screws. An LED 46 is arranged as a light source within the light channel 41 on the circuit board 44. The LED 46 is preferably an SMD LED of any color. Several such LEDs can also be arranged in the light channel 41, for example in different colors, to create a multi-colored indicator light.

[0040] The channel walls 42 of the light channel 41 can either be smooth and reflective so that light from the LED 46, which is emitted laterally and not directly upwards through the cutouts 29 and 36, is potentially reflected upwards. This can contribute to the increased light intensity of the indicator light 20. However, this light can also, due to its oblique angle relative to the top of the mask 26 or the cooktop 12, cause the indicator light 20 to appear less sharp when viewed from above. In this case, the light channel 41 and its channel walls 42 should be as matte and non-reflective as possible. They can also be coated black, for example.

[0041] In the assembled state shown in Fig. 5, it can be seen that the lower cover layer 35, which according to the invention is matte black or non-reflective and points towards the spacer 40, prevents light from the LED 46 from being reflected back downwards towards the top of the spacer 40.

[0042] In the aforementioned further embodiment of the invention, it is also conceivable that not only is a lower cover layer 35 with a corresponding cutout 36 provided on the underside of the mask 26 to prevent reflection towards the spacer 40 or its upper surface, but additionally or alternatively also on the upper surface of the spacer 40 itself. This further increases the certainty that light is not coupled laterally into the transparent layer of the mask 26 by reflection similar to that shown in Fig. 3, where it is further coupled laterally at an oblique angle and then emitted upwards at an unforeseen location, for example, an adjacent upper cutout in the upper cover layer 28.

Claims

Patent claims 1. Display device for an electrical appliance, the display device comprising: a planar display panel which is at least partially transparent, a planar mask with a top and a bottom below the display panel, wherein the planar mask is generally opaque and has light passages in the opaque area, wherein the light passages have the form of illuminated indicators to be displayed, a spacer with a top and a bottom, which is planar and which has light channels extending from the top to the bottom, wherein the light channels correspond to and are arranged in a corresponding manner with the light passages of the mask. Light sources below the spacer, wherein the light sources are arranged in or below the light channels, characterized in that the spacer has a matte or black or non-reflective surface on its upper side, which faces the mask, and / or the mask has a matte or black or non-reflective surface on its lower side, which faces the spacer.

2. Display device according to claim 1, characterized in that it has a component carrier which is arranged on the underside of the spacer, wherein the light sources are arranged on the component carrier and electrically connected, 3. Display device according to claim 1 or 2, characterized in that the mask consists of a translucent material, in particular a transparent material, and has an opaque covering layer on at least one side, preferably on the upper side facing the display aperture, wherein the covering layer is preferably applied over the entire surface and has been removed in the form of the light display.

4. Display device according to one of the preceding claims, characterized in that the thickness of the mask is less than 2 mm, preferably between 0.05 mm and 0.5 mm.

5. Display device according to one of the preceding claims, characterized in that the spacer is at least as large as the mask and has a corresponding shape, wherein preferably the mask does not project beyond the spacer on any outer side or the spacer projects beyond the mask on every outer side.

6. Display device according to one of the preceding claims, characterized in that the spacer is made of opaque material, preferably of a different material than the material for the top.

7. Display device according to one of the preceding claims, characterized in that the top of the spacer and / or the bottom of the mask is provided with a black coating having a matte black surface, wherein the black coating is made of a different material than the spacer or the mask, wherein the thickness of the black coating is preferably less than 1 mm, preferably between 0.02 mm and 0.5 mm.

8. Display device according to one of claims 1 to 6, characterized in that the top of the spacer and / or the bottom of the mask is roughened by subsequent processing such as grinding or etching.

9. Display device according to one of the preceding claims, characterized in that no material is present in the light channels of the spacer or the light channels are designed as empty openings, wherein preferably the side walls of the light channels are non-reflective or matte.

10. Display device according to one of the preceding claims, characterized in that the mask has no coating and is untreated on the underside facing the spacer, wherein in particular the material of which the mask essentially consists forms the underside.

11. Electrical appliance with a display device according to one of the preceding claims, characterized in that the display panel is inserted into an outer surface of the electrical appliance or is part of this outer surface or forms a complete outer surface of the electrical appliance.

12. Electrical appliance according to claim 11, characterized in that it is a hob with a hob plate and heating devices on the hob plate, wherein the hob plate forms the display panel and is made in particular of a translucent material such as glass ceramic or tempered glass.

13. Method for manufacturing a display device according to one of claims 1 to 10, characterized in that the top of the spacer and / or the bottom of the mask are made matte or non-reflective by coating or by subsequent processing, wherein the subsequent processing is preferably grinding or roughening or etching.

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