Decorative part with planar light guide

Abstract

The present invention relates to a surface light guide (1) comprising at least three layers (3, 4, 5, 7), two of which are formed as films (4) with a lower refractive index than a light guide layer (3) arranged between them, the film (4) comprising a light out-coupling structure (6). The present invention is characterized in that the layers (3, 4, 5, 7) form a film composite (2), in which the light guide layer is formed as a film (3). Furthermore, the present invention relates to a light-emitting device comprising such a surface light guide (1) and an in-coupling light guide (8) coupled thereto. Furthermore, a decorative part (10) is described in which a light source, comprising light-emitting means (14, 16) and an in-coupling light guide (8), coupled to the surface light guide (1) is arranged such that the surface portion is actively illuminated and the light-impermeable surface portion obscures the light source and the connection when viewed in the line of sight (B).

Description

[Technical field]

[0001] The invention relates to a decorative part comprising an areal light guide for active illumination of a surface area of ​​the kind defined in detail in the preamble of claim 1. [Background technology]

[0002] Planar light guides are known in principle from the prior art. WO 2005 / 023363 describes an illumination device with such a planar light guide. The light guide is formed from two films which are connected to the actual light guide in that the material of the light guide, for example polycarbonate, is embedded by injection molding between two films having a lower refractive index than the light guide. The entire construction can thereby be realized relatively flat with a component thickness of only a few millimeters, typically 3 millimeters or more. However, this does not allow significant flexibility. With the dimensions typically required for injection molding, the above-mentioned thin constructions of less than 3 mm are not realistic either.

[0003] US Patent No. 5,399,633 claims a surface lighting element comprising a light source and a surface light guide, as well as a transparent film, where the film and the light guide are made from materials having different refractive indices, and the light guide is formed by rear injection molding of the film, i.e. similar to the prior art described above.

[0004] US Patent No. 5,399,663 describes a flexible optical element with an optical waveguide. US Patent No. 5,399,663 describes a light guide film that can be incorporated into a film composite.

[0005] US Patent No. 5,399,436 further describes a surface emitter composed of several different layers, where each core is a transparent support structure, which is combined with a light guide formed from a film, thereby forming a support structure having a lower refractive index than the original light guide film, which is further covered by another film with a lower refractive index and a separation structure to separate the light through the transparent support structure.

[0006] US Pat. No. 5,399,633 describes a similar arrangement using a coupling element or light coupling by a light guide made of optical fibers.

[0007] US Pat. Nos. 5,993,343 and 5,993,633 describe two light guide films that can be placed on vehicle windows.

[0008] These last-mentioned constructions are then not very flexible and are relatively bulky, especially with regard to their thickness.

[0009] An illuminated decorative part is known from DE 199 02 04 113 A1. In this case, the light beam generated by the light emitting means is coupled into a composite film having a light guide layer. A very similar decorative part is also known from DE 199 02 04 113 A1.

[0010] For other prior art, reference is also made to US Pat. No. 5,399,623 and US Pat. No. 5,499,633, which are from the field of display illumination or backlighting and also feature thin light guide layers. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] DE 102019001333 A1 [Patent Document 2] German Patent No. 102014006490 [Patent Document 3] US Patent Application Publication No. 2007 / 0133935 [Patent Document 4] DE 102019202804 [Patent Document 5] DE 102013021600 [Patent Document 6] International Publication No. 2007 / 077099 [Patent Document 7] DE 102019112889 [Patent Document 8] DE 102013010163 [Patent Document 9] DE 102014112470 [Patent Document 10] US Patent Application Publication No. 2021 / 0055567 [Patent Document 11] US Patent Application Publication No. 2006 / 0002675 [Patent Document 12] European Patent Application Publication No. 2157366 Summary of the Invention [Problem to be solved by the invention]

[0012] SUMMARY OF THE DISCLOSURE It is therefore an object of the present invention to provide an improved decorative part with a surface light guide for actively illuminating a surface portion. [Means for solving the problem]

[0013] In that case, a decorative part according to the invention, which comprises an area light guide for actively illuminating a surface part and at least one light source arranged on the end side of the area light guide, is intended to include at least one light emitting means, the light source being directly or indirectly connected to the area light guide, which is arranged behind the non-light-transmitting surface part in a concealed manner in the direction of sight to the decorative part and connected to the area light guide. In other words, in such a decorative part, the assembly and coupling of the light source is arranged in the area behind the part that is not particularly transparent to light. This part, which is formed as an opaque surface part of the decorative part, conceals the light coupling to the area light guide as well as the light source itself. Inhomogeneities as well as particularly brightly lit points or areas are thereby covered by a kind of shade, so that the decorative part according to the invention allows a very homogeneous, uniform and easily produced color scheme that allows a large design freedom while giving an impression of high quality through a corresponding transparent decoration arranged directly or upstream in the area of ​​its actively lit surface.

[0014] The surface light guide of the decorative part according to the invention comprises three layers, similar to the light guide described in the prior art at the beginning, two layers formed as films having a lower refractive index than the light guide layer arranged between them. Furthermore, one of the films has a light separation structure, similar to the prior art at the beginning. Thus, according to the invention, these layers form a film composite, in which the light guide layer is also formed as a film. Such constructions, which have always been made from surface materials made of hard materials, for example polycarbonate or the like, or by integral or rear injection molding, in principle always have a relatively large thickness, typically at least 3-5 mm, and a relatively low flexibility. The construction according to the invention, which consists of three films forming a film composite, the two outer films having a lower refractive index than the light guide film located in the middle, avoids all these disadvantages. In practice, a very compact construction is obtained, which can be easily realized with a thickness of the film composite much smaller than 1 millimeter, in particular a thickness of about 0.5 mm.

[0015] The films of the planar light guide are coextruded, which allows for easier and more efficient production. The films themselves can consist, for example, of two polymethylmethacrylate (PMMA) films, between which a film made of polycarbonate (PC) is inserted as light-guiding layer. The entire construction can be produced simply and efficiently by coextrusion, with very small layer thicknesses and high mechanical strength compared to the layer thickness.

[0016] In the decorative part according to the invention, the light source is formed by an in-coupling light guide with at least one integrated light emitting means. This is of course advantageous, in particular, if the surface light guide consists of a film composite, in which case, in particular, the surface light guide and the in-coupling light guide together can form one light emitting element.

[0017] In an advantageous development of the decorative part according to the invention, it can furthermore be provided that the film composite is provided with a protective layer on one or both sides. This protective layer can itself also be a film, for example, in each case another polycarbonate film, but it can also be a paint or the like. Naturally, the protective layer can also be omitted in constructions in which, for example, a decoration is applied on one side and a transparent or, in particular, opaque support is applied on the other side by injection molding or the surface light guide or the film composite consisting of three layers is directly processed by integral injection molding.

[0018] The light-emitting element of the decorative part according to the invention can include the planar light guide described above and a light guide of a larger thickness combined with a film composite, the thickness being in contrast to the light-guiding film of the film composite, where this light guide, not particularly made of a film, is used to couple light into the light-guiding layer made as a film of the planar light guide.

[0019] According to an advantageous development, it can therefore be provided that this light guide of greater thickness is combined with at least one light emitting means. In that case, the combination can be realised in such a way that the light emitting means or means, in particular LEDs, can be mechanically coupled to the construction, for example in a strip made of polycarbonate. However, the light emitting means and optionally the control electronics for the light emitting means can be integrated directly into this light guide of greater thickness, for example embedded by injection moulding.

[0020] The role of this larger thickness light guide, which can also be called an in-coupling light guide, is then to accept the light emitted by the light emitting means accordingly, especially when various colors are used, and to homogenize this light within its entire length before it is introduced into the light-guiding film as light-guiding layer. The light yield of the light emitting means can thus be ideally utilized, which is not directly possible with a film due to its small thickness. Furthermore, polychromatic light always requires a certain light propagation length in the light guide until a homogeneous color mixture is obtained, which can also be achieved in the larger light guide before the homogeneous light is coupled into the corresponding light-guiding layer of the planar light guide. The larger thickness light guide can then also be glued, welded or directly injection-molded into the film composite. This light guide can then be made conventionally, i.e. surrounded by an air gap, for example from a single material, such as polycarbonate, whereby the light-guiding properties, i.e. total internal reflection at the interface between the material of the light guide and air, are achieved. Alternatively, it is also conceivable that this light guide of greater thickness is surrounded by a coating made of a material with a lower refractive index. This material may also be, for example, a film made of PMMA or the like, so that in principle it is possible to provide a construction of a light guide of greater thickness from the prior art mentioned at the beginning of the document WO 2007 / 023366. Naturally, alternative coatings, for example by paint or the like, are also conceivable.

[0021] Another very advantageous embodiment of the decorative part according to the invention can then further provide that the surface light guide is connected to the support and the decoration by co-extrusion, calendering and / or back injection molding. In that case, this construction consisting of the support, the decoration and the surface light guide can be integrally injection molded to the non-light-guiding surface parts and the light source, or vice versa. Overall, a very compact and efficient decorative part results, especially if the surface light guide is formed as the above-mentioned film composite. In that case, the components are very simply and efficiently connected to one another within the light guide, resulting in a stable construction that does not creak and the individual parts cannot collide with one another even if the decorative part is used for a relatively long period of time, for example when used in a vehicle, due to vibrations and the inevitable relative movement of the parts in the vehicle.

[0022] The planar light guide according to the present invention, the light-emitting device according to the present invention, and the decorative part according to the present invention provide further advantages and embodiments which will become apparent from the examples which are described in detail below, in particular with reference to the drawings. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic diagram of a possible embodiment of a planar light guide. [Diagram 2] FIG. 2 is a schematic cross-sectional view of a possible decorative part according to the present invention having a first embodiment of a light-emitting element. [Diagram 3] 2 is a schematic cross-sectional view of a possible decorative part according to the present invention having another embodiment of a light-emitting element. [Figure 4] 11A-11D are diagrams of some possibilities for coupling the light emitting means to the light guide. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In the illustration of FIG. 1, a possible structure of a surface light guide 1 made of a film composite 2 is shown in a schematic manner. The film composite 2 consists of at least three films. A central light guide layer is formed as a light guide film 3. This is realized, for example, as a polycarbonate film. This light guide film 3 is surrounded by two films 4, 5 having a lower refractive index than that of the light guide film 3. The two films 4, 5 can be made, for example, from PMMA (polymethylmethacrylate). One of these two films, here the film 5 illustrated in FIG. 1, further comprises separation structures, indicated with 6, in the film 5. These separation structures 6 can be realized, for example, by a polished surface, by structures provided by laser processing, by structures printed by screen printing, or the like. They can be adapted to a subsequent curvature or the like of the surface light guide 1 in order to achieve a uniform and homogeneous light separation independent of the three-dimensional geometric form of the subsequent construction. In that case, the direction in which the light is separated is upward in the illustration of FIG. 1, and thus the planar light guide 1 is viewed from above according to the viewing direction B.

[0025] For the actual film composite 2 of the surface light guide 1, this construction made of the three films 3, 4, 5 described here is entirely sufficient. Depending on the further processing, this construction can be realized with a molded decorative layer, a molded support layer, or the like. In particular, this construction can also be three-dimensionally formed in a corresponding injection mold, and then completed by rear injection molding a support layer and / or providing a decorative layer on the surface above in the viewing direction B, and hardened to the shape predetermined by the mold.

[0026] Independently of this, in addition to the three layers 3, 4, 5 mentioned above, it is also possible to incorporate two protective layers 7, for example in the form of thin polycarbonate films, together in the film composite 3. This optional embodiment can be seen in the illustration in Fig. 1, where, as mentioned above, the two protective films 7 can also be omitted. Depending on the construction, only one of the two protective films 7 can be provided, for example only the protective film on the visible side, if the support is integrally injection molded on the opposite side.

[0027] Unlike the constructions mentioned in the prior art at the outset, where the light guide can be produced only by injection molding, for example where the light guide is embedded between two PMMA films by injection molding, here it is possible to produce the entire film composite 3 by coextrusion and therefore to make it much thinner. The film composite 3 shown exemplarily in FIG. 1 then has a thickness of less than 1 mm. By omitting one or both protective layers 7, the thickness of the construction can be further reduced, so that a functional planar light guide can be realized, for example, consisting of three films 3, 4, 5 with a layer thickness of about 0.5 mm. The enclosed light guide layer of the light guide film 3 is then somewhat thicker than the respective layer thickness of the adjacent PMMA films 4, 5, as shown approximately to scale in the illustration in FIG. 2.

[0028] In principle, light coupling from the edge into such a film composite 2 is conceivable. In practice, however, this is very difficult, since even small light emitting means such as microLEDs have a certain size and width, and they emit light in particular at an angle of typically about 120°. A significant part of the light would therefore be lost in the case of direct coupling to the edge of the film composite 2.

[0029] Thus, the film complex 2 of the surface light guide 1 can preferably be combined with an in-coupling light guide 8 having a larger thickness. This is shown in principle in the following illustration of FIG. 2. The construction shown there comprises a decorative part 10 with a surface light guide 1. It is constituted by a film complex 2 with in particular three films 3, 4, 5, of which only a separation structure, designated 6, is again shown in the illustration of FIG. 2 in order to be able to recognize the orientation of the film complex 2 of the surface light guide 1. Here, the light direction is upwards, so that the viewing direction B runs from top to bottom towards the decorative part 10. It consists of a plastic support 11 and a decorative plate, for example made of polycarbonate, wood, aluminum or similar. The decorative plate is back-illuminated by light that is separated by the surface light guide 1 in the direction opposite to the viewing direction B. The light-transmitting surface portion 12 is further adjoined by an opaque surface portion, designated here 13 and indicated with a correspondingly modified hatching. This part 13 is non-transparent to light and therefore, seen from the viewing direction B, hides the components located behind it in the viewing direction B. In the embodiment shown here, this is an in-coupling light guide 8 with a greater thickness, which is formed as a conventional light guide and has a corresponding separation structure 9 in a manner known per se. This separation light guide can be realized, for example, by integral injection molding into the film composite 2 of the areal light guide 1 in order to transmit the light coupled into the light guide 8 via the luminous means described below into the areal light guide. In that case, from the viewing direction B, the structure of the light guide 8 and its connection with the film composite 2 are located below the light-non-transparent surface, so that the in-coupling and transmission of light is not visible through the light-transmitting part 12 of the decorative plate. That is to say, the decorative part 10 can be realized with a homogeneous illumination of its actively illuminated surface part 12 by the film composite 2 of the areal light guide 1, without the typically inhomogeneously illuminated areas of the light in-coupling points being visible.

[0030] In that case, the conventional light guide 8 is used to collect the light of the individual light emitting means, and due to its larger thickness, the light of the light emitting means can be collected very well, so that a large part of the light reaches the conventional light guide 8 and through it the surface light guide 1. Furthermore, light emitting means of different colors or light emitting means capable of producing different colors, for example RGB-LEDs, can be used. The size of the conventional light guide 8 provides a sufficient light propagation path, so that the colors are well mixed and the light color in the area of ​​the surface light guide 1 is homogenous.

[0031] In the embodiment shown here, the conventional light guide 8 is surrounded by air, so it is sufficient to make it from a material such as polycarbonate, for example, since the surrounding air then forms an ambient environment with a lower refractive index than that of polycarbonate, and a corresponding light guiding effect is achieved, and light can be almost completely coupled into the film composite 2 of the planar light guide 1.

[0032] An alternative embodiment can be seen in the illustration of FIG. 3. This corresponds roughly to the illustration shown in FIG. 2. In this case, however, a conventional light guide 8 is injection molded into the film composite 2 construction on the one hand and into the decorative part 10 construction on the other hand. Here, the construction is, for example, coated with a surface portion 13 that is non-transparent to light. In order to ensure the properties of the light guide in such an integrally injection molded or completely injection molded construction, in which a plastic support 11 further surrounds the conventional light guide 8, which is also conceivable here, it is then necessary to provide the conventional light guide 8 with a corresponding coating made of a material with a low refractive index. The light guide can be surrounded by a film made of PMMA, for example, or coated with a corresponding paint having low refractive index properties.

[0033] Otherwise, the same applies to the arrangement shown in FIG. 3 as has already been explained within the scope of FIG.

[0034] Finally, in the illustration of Fig. 4 three different possibilities are shown for coupling light into a conventional light guide 8. In the illustration of Fig. 4a a number of light emitting means 14, here RGB-LEDs, are mechanically coupled to the light guide arrangement and correspondingly light is provided to the surface of this arrangement, which is transmitted according to the depicted arrow, indicated with 15, to the in particular integrally injection moulded film composite 2.

[0035] An alternative arrangement is shown in the illustration of Fig. 4b. Instead of a number of small light emitting means 14, as in the illustration of Fig. 4a, here two relatively large light emitting means 16 are respectively arranged at the end faces of a conventional light guide 8 and couple the light in. The light can then be separated from the conventional light guide 8 via a separating structure, not shown here, for example upwards or downwards, or towards or away from the viewer.

[0036] In the illustration of Fig. 4c, further variants of conventional light guides 8 can also be seen. The light emitting means 14 are here again formed as LEDs, which are smaller than those shown in Fig. 4b. In contrast to the previous illustrations, they are embedded by direct injection into the material of the light guide 8, i.e. for example polycarbonate. Naturally, it is also conceivable that the arrangement has larger light emitting means in the region of the end faces in addition to or instead of the arrangement shown here. The light incouplings of Fig. 4a and Fig. 4b can also be combined with one another. It is furthermore conceivable to couple light correspondingly into conventional light guides 8 on the one hand via injected light emitting means 14, 16 and on the other hand via further light emitting means 14, 16 which are simply coupled in addition to this.

Claims

1. A decorative part (10) comprising a surface light guide (1) for actively illuminating a surface portion (12) and at least one light source arranged on an end side of the surface light guide (1), the surface light guide (1) having at least three layers (3, 4, 5, 7), two layers formed as films (4) having a lower refractive index than a light guide layer (3) arranged between the two layers, one of the films (4) having a light separation structure (6), the layers (3, 4, 5, 7) forming a film complex (2), the light guide layer (3) being formed as a film (3) in the film complex, the light source comprising at least one light emitting means (14, 16) indirectly connected to the surface light guide (1), the light source being arranged behind a light non-transmitting surface portion (13) in a concealed manner as viewed in a line of sight (B) towards the decorative part (10) and connected to the surface light guide (1), The films (3, 4, 5, 7) are coextruded, said light source being formed by an in-coupling light guide (8) having at least one integrated light emitting means (14, 16), The planar light guide (1) and the in-coupling light guide (8) are characterized in that they have a light emitting element consisting of the planar light guide (1) and a light guide (8) of greater thickness combined with the film composite (2).

2. A decorative part (10) comprising a surface light guide (1) for actively illuminating a surface portion (12) and at least one light source arranged on an end side of the surface light guide (1), the surface light guide (1) having at least three layers (3, 4, 5, 7), two layers formed as films (4) having a lower refractive index than a light guide layer (3) arranged between the two layers, one of the films (4) having a light separation structure (6), the layers (3, 4, 5, 7) forming a film complex (2), the light guide layer (3) being formed as a film (3) in the film complex, the light source comprising at least one light emitting means (14, 16) indirectly connected to the surface light guide (1), the light source being arranged behind a light non-transmitting surface portion (13) in a concealed manner as viewed in a line of sight (B) towards the decorative part (10) and connected to the surface light guide (1), The films (3, 4, 5, 7) are coextruded, said light source being formed by an in-coupling light guide (8) having at least one integrated light emitting means (14, 16), The surface light guide (1) is connected to the support (11) and the light-transmitting decoration (12) by co-extrusion, calendaring and / or rear injection molding, and a structure including the surface light guide (1), the support (11) and the light-transmitting decoration (12) is injection molded onto the light-impermeable surface portion (13) and the light source, or the light-impermeable surface portion and the light source are injection molded onto the structure (10).

3. 3. Decorative part (10) according to claim 1 or 2, characterized in that the film composite (2) has a thickness of less than 1 mm.

4. Decorative part (10) according to any one of claims 1 to 3, characterized in that one or both surfaces of the film composite (2) are provided with a protective layer, in particular a protective film (7).

5. 2. A decorative part (10) according to claim 1, characterized in that the light guide (8) of greater thickness is glued, welded or integrally injection molded into the film composite (2).

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