Component having at least one backlit surface and corresponding method for producing the same

Abstract

A component with at least one backlit surface, comprising a flexible substrate layer, a light-conducting layer arranged on the substrate layer, and a light source for illuminating the end side of the light-conducting layer, the component being distinguished by the fact that the light-conducting layer consists at least predominantly of a highly viscous, optically transparent material and that the light-conducting layer comprises optically transparent microbodies. In addition, a method for producing a backlit covering of a surface is proposed, the method comprising the steps of: a. providing a flexible substrate; b. arranging a light source on the substrate, applying a flexible, highly viscous and optically transparent layer on the substrate in such a way that a light exit opening of the light source is directed toward the end side of the transparent layer, wherein the transparent layer comprises optically transparent microbodies.

Description

Technical Field

[0001] The invention relates to a component having at least one backlit surface, a flexible substrate layer, a light guide layer arranged on the substrate layer, and a light source for illuminating the end side of the light guide layer. The invention also relates to a method for producing a backlit covering of a surface. Background Art

[0002] Such components are known from the prior art and are used, for example, for covering switches or as button covers, for example, on switches on steering columns. Current variants use light-conducting films as light-conducting layers, since they can be bent and thus allow deformation of the entire component at least within given limits. The component can thus be adapted to certain geometries. This makes it possible to arrange illuminated surfaces or illuminated symbols at the most diverse locations, for example at the most diverse locations of a motor vehicle, wherein the lighting device is usually a backlight.

[0003] In this case, a backlighting device is generally understood to be a lighting device which at least creates the impression that the backlit surface or the backlit component is emitting light as if autonomously.

[0004] For this purpose, light, for example light from an LED, is coupled laterally into a film applied to a substrate. A pattern corresponding to the symbol to be displayed can then be embossed on the film, so that light is coupled out in the embossed area and the desired symbol becomes visible.

[0005] Likewise, other solutions are known in which the light is not coupled into the optical waveguide at the side, but the light source is arranged directly behind the symbol to be shown or behind the surface to be illuminated. From DE 20 2017 104 082 U1, for example, a shaped part or covering part for the interior of a vehicle is known, which has a transparent or light-scattering carrier on which an opaque layer is arranged. A decorative layer and a protective layer are arranged above the opaque layer, wherein the opaque layer and the decorative layer are interrupted by congruent gaps, respectively. A translucent filling material is introduced into these gaps, which is coordinated with the decorative layer in color so that the observer perceives a surface that is as uniform as possible in the unilluminated state. If a light source arranged behind these gaps in the viewing direction is now turned on, the light is therefore transmitted through the translucent filling material and makes these gaps or the symbols formed by these gaps visible. Microscopic scatterers, such as microscopic glass balls, can be introduced into the translucent material as a scattering aid.

[0006] Components known from the prior art are either not deformable when using inflexible light guide plates or other inflexible materials, or are only deformable to a limited extent when using light guide films as light guide elements. Such films generally have the following properties: although they can be bent around an axis and thus deformed due to their planar configuration, further deformations around axes different from the first axis are not possible after such bending. In short, the most complex shape that can be formed with such light guide films is a cylinder. Therefore, only so-called 2.5-dimensional deformations are possible. Summary of the invention

[0007] The object of the present invention is therefore to specify a component of the generic type which can be deformed more flexibly, wherein this deformability should also be retained after the individual layers of the component have been joined. It is also an object of the present invention to specify a method of the generic type by means of which such a component can be produced.

[0008] This object is achieved according to the invention by a component of the type described in the introduction having at least one backlit surface, which is distinguished by the fact that the light guide layer consists at least predominantly of a highly viscous, optically transparent material and that it comprises optically transparent microbodies.

[0009] The component can be, for example, a cover for a switch or other operating element. It can also be, for example, a flat cover of any structure within the interior of a motor vehicle. A substrate is understood in particular to be a carrier material that can form the basis of a component. Here, it usually assumes structural tasks. At the same time, other functions can also be fulfilled by the substrate, such as electronic circuits and, for example, sensors or the like. For example, the substrate can be a printed circuit board, in particular a flexible printed circuit board.

[0010] “The layer or substrate is flexible” is understood in particular to mean that the layer or substrate is deformable, in particular bendable. Here, only small elastic restoring forces or no elastic restoring forces are generated, so that plastic deformability exists.

[0011] The embodiment according to the invention has the following advantages: Three-dimensional re-deformation of the overall component is now possible, since relatively rigid components such as plate-shaped light conductors or light conductor films are no longer used. Instead, a flexible, highly viscous material is used as the light conductor, which remains freely deformable even after being combined with other layers.

[0012] A highly viscous material is understood here in particular to be a material which, in the form of a thin layer, has very little rigidity and / or is viscous. This is therefore an amorphous material which has only hardened to such an extent that it changes its shape reversibly under the action of a force, wherein the elasticity of the material is very low.

[0013] According to a preferred embodiment, the light-conducting layer consists at least predominantly of OCA glue. OCA glue is understood here in particular to be a so-called "optically clear adhesive". Such materials are known in particular from the mobile phone industry, where they are used to connect different layers of a display device to one another. For example, in the case of such a display device, the outermost glass layer can be fixed to the actual display device with the aid of OCA glue. In this case, OCA glue is used in particular for this purpose in order to avoid undesired light reflections at the boundaries of different display device layers.

[0014] OCA glue is particularly distinguished by the fact that it has a high transmission of, for example, more than 90%, more than 95%, more than 98% or more than 99%, especially more than 99.5%, for light in the optically visible range, and by the fact that it remains flexible and deformable even after hardening. OCA glue is also generally very resistant to temperature changes, so that, for example, temperatures above 85°C and below -40°C do not have a negative impact on the material over a period of more than 500 hours, respectively. Suitable OCA glues can have a refractive index in the range of 1.4 to 1.6, especially in the range of 1.45 to 1.5. In addition, OCA glue has high adhesion and therefore high adhesion strength and high cohesive strength. OCA glue can be manufactured, for example, based on an acrylic or silicone base and hardened by means of ultraviolet radiation, by means of visible light, high-energy radiation or in a catalytic manner.

[0015] The optically transparent microbodies can be at least partially embedded in the light-conducting layer and at least partially protrude from the light-conducting layer on one side of the light-conducting layer. Such a structure simplifies the production of the optically transparent layer, because, for example, the OCA glue can be produced in large quantities as a thin layer and provided for further use, and can be brought into the form according to the invention by subsequently loading the OCA glue with optically transparent microbodies. OCA glue is usually produced in large quantities as a thin layer and transported to the processing plant in this shape for further processing. Then, the following modification can be made directly in the processing plant so that the OCA glue is pre-processed for further processing according to the invention. For this purpose, the OCA glue can be sprinkled with optically transparent microbodies, for example. Similarly, the surface of the OCA glue can be contacted with the microbodies in other ways, for example, the surface can be immersed in a large number of microbodies. These microbodies are then attached to the OCA glue due to the adhesive properties of the OCA glue. Excess microbodies can then be removed from the OCA glue, for example by brushing, scraping, or by a tumbling motion.

[0016] Depending on the embodiment, it may be advantageous to have the microbodies protrude from the light-conducting layer on the side facing away from the substrate layer. It may also be advantageous to have the microbodies protrude from the light-conducting layer on the side facing the substrate layer. The surface from which the microbodies protrude is at least partially passivated in this case due to the adhesive effect of the OCA glue, which may be advantageous or disadvantageous depending on the intended use or the specific configuration of the component. For example, for floodlights, it may be advantageous if the microbodies are arranged in the region of the surface of the optically transparent layer facing away from the substrate.

[0017] These microbodies can be spheres, hollow spheres, ellipsoids or polyhedrons made of glass or plastic. Spheres or hollow spheres made of glass are hereby inexpensively manufacturable, robust and simple in handling. However, other materials, such as plastics, may also be used to manufacture microbodies.

[0018] In a further development of the invention, the microbodies form a layer that is substantially as densely packed as possible in the sense of a monolayer. The passivation effect on the adhesion of the OCA glue is maximized. At the same time, the overall scattering effect of the microbodies is increased.

[0019] It has proven to be expedient if the microbodies have a diameter in the range between 50 μm and 300 μm, preferably between 100 μm and 200 μm.

[0020] Good results are also achieved if the light-conducting layer has a thickness of between 0.5 mm and 2 mm, preferably between 1 mm and 1.5 mm. However, thinner layers, for example with a thickness of between 0.2 mm and 1 mm and in particular between 0.2 mm and 0.5 mm, are also possible.

[0021] According to an extension of the invention, the light-conducting layer consists of a first sublayer and a second sublayer, which are separated from one another by a film, wherein only one of the sublayers has microbodies. In this case, the film can prevent the microbodies from moving in an unhindered manner in the light-conducting layer and thus, for example, unintentionally sinking from the surface of the light-conducting layer facing away from the substrate to the surface of the light-conducting layer facing the substrate or vice versa. This may be possible in other cases due to the viscosity of the material of the light-conducting layer. The two sublayers can be dimensioned here so that the total thickness of the sublayers corresponds to the previously mentioned thickness of the light-conducting layer in the embodiment with only a single light-conducting layer. It is also possible that the two sublayers have corresponding thicknesses and thus increase the total thickness of the light-conducting layer. The total thickness can then be up to twice the thickness mentioned previously.

[0022] Advantageously, it is possible to couple light into a sublayer without microbodies. After being transferred into the sublayer provided with microbodies and before being coupled out of the light guide element, the light can then first propagate unhindered in precisely that sublayer without microbodies.

[0023] As light sources, LEDs, for example so-called sidefire LEDs, can be used. However, any other light source, such as a diode laser or other light sources, can also be used. Due to the high light output and the low-cost production possibility, LEDs are currently preferred over other light sources in most applications.

[0024] According to an advantageous embodiment, no microbodies are arranged in surface areas in which light is not to be coupled out. It is thus possible, solely by structuring the light-conducting material, to achieve a configuration in which only certain areas of the surface of the component emit light toward an observer, so that, for example, an illuminated symbol can be displayed.

[0025] In order to increase the light output of the overall system, the side of the substrate layer facing the light-guiding layer may have reflective properties. In other words, the substrate layer may be mirror-coated.

[0026] The object is also achieved by a method for producing a backlit covering of a surface, the method comprising the following steps:

[0027] a. Providing a flexible substrate;

[0028] b. Arranging the light source on the substrate;

[0029] c. A flexible, highly adhesive and optically transparent layer is applied to the substrate in such a way that the light exit opening of the light source is directed toward the end face of the transparent layer, wherein the transparent layer has the optically transparent microbodies.

[0030] This method makes it possible to cover or mask any desired surface in a simple and cost-effective manner, wherein the surface can be selectively backlit.

[0031] The method according to the invention can be extended by the following additional steps:

[0032] d. Applying a covering layer onto the optically transparent layer, wherein the covering layer is likewise optically transparent in some areas and / or has recesses in some areas.

[0033] A component manufactured in this way is obtained so that it has a usable surface that can be backlit and / or provided with illuminated symbols. Such a component can be an operating element or a display element, in particular an operating element or a display element in a motor vehicle.

[0034] The number of components available for the method according to the invention can be increased by carrying out a three-dimensional deformation of the surface after step c. This additional step makes full use of the advantages according to the invention. The backlit surface can also be deformed after production or after the individual layers have been joined together, which creates a large number of new application possibilities.

[0035] As already described above in a similar manner, the method can be extended in such a way that a transparent layer is produced before step c. by producing a segment from the provided, plate-shaped batch of highly viscous, optically transparent material and sprinkling the segment with transparent microbodies. It is possible in a simple manner to modify an OCA adhesive that is available on the market in such a way that it can be used according to the invention. Such an OCA adhesive can also be referred to as an OCA adhesive tape.

[0036] Likewise, the method according to the invention can be strengthened by applying an additional layer of a highly viscous, optically transparent material which does not contain transparent microbodies to the substrate or to the optically transparent layer before or after the application of the optically transparent layer. The additional layer can be separated from the first optically transparent layer by a film. The advantages already described above of a multi-part system with an optically transparent layer are then obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Embodiments of the present invention are further described with reference to the accompanying drawings and the following description.

[0038] Figure 1 A first embodiment of a component according to the invention is shown in a cross-sectional side view;

[0039] Figure 2 A second embodiment of a component according to the invention is shown in a cross-sectional side view;

[0040] Figure 3 A third embodiment of a component according to the invention is shown in a cross-sectional side view; and

[0041] Figure 4 A top view of an embodiment of an optically transparent layer according to the invention is shown. DETAILED DESCRIPTION

[0042] Figure 1 A first embodiment of a component 2 according to the invention is shown in a cross-sectional side view. The basis of the component 2 is formed by a substrate 4, which can be a flexible substrate. For example, the substrate 4 can be a PCB (English "printed circuit board", German Leiterplatte (circuit board)) or FCB (English "flexible circuit board", German flexible Leiterplatte). A light source 12 is arranged on the substrate 4. The light source 12 is preferably a light emitting diode, such as a so-called side-emitting LED. A mirror element 14, such as a mirror film (Spiegelfolie), is arranged at the end of the substrate 4 opposite to the light source 12. The mirror element 14 is optional and can improve the light output.

[0043] The light source 12, the substrate and the mirror element 14 form a roughly U-shaped boundary of the following space in the cross section shown, wherein a transparent layer 8 is arranged in the space, which can be composed of OCA glue, for example. Glass beads 10 are embedded in the transparent layer 8, which are located near the surface 18 of the transparent layer 8 facing away from the substrate 4. In the present case, the surface 18 is the surface from which the light from the optically transparent layer 8, which is irradiated by the light source 4, should be coupled out and thus coupled out from the monolithic component 2. In the following text, this surface is also referred to as the coupling-out surface 18.

[0044] In the figure above, a cover 6 is arranged on a transparent layer 8. The cover 6 forms the visible side of the component 2 and closes the component to the outside. The substrate is usually arranged on other components or connected to other components in the installed state of the component 2. The side of the substrate 4 facing the optically transparent layer 8 can have a reflective coating, so that the proportion of light that leaves the component as desired through the outcoupling surface is also maximized in this way.

[0045] Further layers, such as films or other layers, can be arranged between the substrate 4 and the optically transparent layer 8. However, the optically transparent layer 8 can also be in direct contact with the substrate 4 and / or with the cover 6. Likewise, further layers, such as films, can also be arranged between the cover 6 and the optically transparent layer 8.

[0046] In the embodiment shown, the optically transparent layer 8 completely surrounds the glass balls. However, it is also possible that the glass balls 10 partially or mainly protrude from the optically transparent layer 8. During the operating phase with the activated lighting device or backlighting device, the light emitted by the light source 12 is coupled into the optically transparent layer through the end side 16 of the optically transparent layer 8. The light is reflected on the mirror element 14 and / or on the side of the substrate 4 facing the optically transparent layer 8 and is finally scattered at the glass balls 10 and coupled out from the component 2 through the coupling-out surface 18. The coupling-out surface 18 or the area not covered by the cover 6 is now perceived by the observer as luminous. In the cross section shown, the cover 6 completely covers the coupling-out surface 18. However, it should be seen in the complete, three-dimensional illustration or in the two-dimensional top view of the component that the cover 6 has gaps or optically transparent areas, which can, for example, show symbols.

[0047] Figure 2 A second exemplary embodiment of a component according to the invention is shown in a sectional side view. The substrate 4, the light source 12, the mirror element 14, the cover 6 and the transparent layer 8 with the glass balls 10 can be seen again. The second exemplary embodiment shown is similar to Figure 1The difference of the first embodiment shown in FIG. 1 is that the glass spheres 10 are arranged near the surface of the transparent layer 8 facing the substrate 4. This can be achieved, for example, by the transparent layer 8, for example OCA glue, being applied to the substrate 4 and being in contact with each other. Figure 1 The situation shown in is flipped compared to before the merger.

[0048] Figure 3 A third embodiment of the component according to the invention is shown in a cross-sectional side view. Here, it should also be seen that: substrate 4, light source 12, mirror element 14, cover 6 and transparent layer 8 with glass balls 10. In this embodiment, the optically transparent layer 8 is implemented in two parts. The optically transparent layer consists of a lower OCA layer 20 and an upper OCA layer 22, which are separated from each other by a film 24. In the embodiment shown, only the upper OCA layer 20 has glass balls 10, while the lower OCA layer 22 does not have glass balls 10. Depending on the viscosity of the OCA layer 20, 22 or 8, the glass balls 10 are movable within the layer 20, 22 or 8. The film 24 forms a barrier between the two viscous layers 20 and 22, which the glass balls cannot cross and thus limit the resting position of the glass balls 10 to the upper OCA layer 20. Alternatively, the glass balls can also be arranged in the lower OCA layer 22.

[0049] Figure 4 A top view of an embodiment of an optically transparent layer 8 according to the invention is shown. It can be seen that the OCA glue 8, on which glass balls 10 are distributed. The glass balls 10 are packed as densely as possible here, so that there are only small gaps between the glass balls 10. The glass balls 10 are arranged in a single layer here. In other words, there are only very small gaps between the glass balls. Most of the glass balls 10 are in direct contact with at least one other glass ball. At the same time, there is very little overlap between the individual glass balls 10. In other words, within the scope of production accuracy, there are no areas in which multiple glass balls are arranged one above the other, where "one above the other" means: perpendicular to the main extension direction (Hauptausdehnungsrichtung) of the output coupling surface in terms of layout or sequence.

[0050] Reference numerals list

[0051] 2 Backlighting components

[0052] 4 Substrate

[0053] 6 Covering

[0054] 8 OCA glue

[0055] 10 Glass beads

[0056] 12 Light Source

[0057] 14 Mirror film

[0058] 16 Interface

[0059] 18 Interface

[0060] 20 OCA layer below

[0061] 22 OCA layer above

[0062] 24 Membrane

[0063] 26 OCA layer with glass beads.

Claims

1. A component having at least one backlit surface, the component comprising a flexible substrate layer, a flexible light-guiding layer arranged on the substrate layer, and a light source for illuminating the end side of the flexible light-guiding layer, characterized in that: The flexible optical waveguide layer is composed of a highly viscous, optically transparent material, and the flexible optical waveguide layer has optically transparent microbodies constructed as glass balls or plastic balls, wherein the highly viscous, optically transparent material is OCA glue, wherein the microbodies constitute a layer that is essentially filled as densely as possible in the sense of a single layer, wherein a mirror element is arranged at the end of the substrate layer opposite to the light source, wherein the optical waveguide layer is composed of a first sublayer and a second sublayer, wherein the first sublayer and the second sublayer are separated from each other by a film, wherein only one of the sublayers has the microbodies, and the light is input coupled into the sublayer that does not have the microbodies.

2. The component according to claim 1, characterized in that The optically transparent microbodies are at least partially embedded in the light-guiding layer and at least partially protrude from the light-guiding layer on one side of the light-guiding layer.

3. The component according to claim 1 or 2, characterized in that The microbodies have a diameter in the range between 50 μm and 300 μm.

4. The component according to claim 1 or 2, characterized in that No microbodies are arranged in surface regions from which no coupled-out light is to be arranged.

5. The component according to claim 3, characterized in that The microbodies have a diameter in the range between 100 μm and 200 μm.

6. A method for producing a backlit covering of a surface, the method comprising the following steps: a. Providing a flexible substrate; b. Arranging the light source on the substrate; c. applying a flexible, highly viscous and optically transparent light-guiding layer on the substrate in such a way that the light exit opening of the light source is directed toward the end side of the light-guiding layer, wherein the light-guiding layer has optically transparent microbodies configured as glass spheres or plastic spheres, wherein the flexible, highly viscous and optically transparent layer is composed of OCA glue, wherein, The microbodies constitute a layer that is essentially as densely packed as possible in the sense of a single layer, wherein a mirror element is arranged at the end of the substrate opposite the light source, wherein the optical waveguide layer consists of a first sublayer and a second sublayer, which are separated from each other by a membrane, wherein only one of the sublayers has microbodies, and the light is input coupled into the sublayer that does not have microbodies.

7. The method according to claim 6, characterized in that After said step c. a three-dimensional deformation of said surface is performed.

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