Light-emitting element with improved backlighting and uses thereof

Abstract

The present invention relates to a light-emitting element (1), comprising: a light source assembly (2) having at least one light source (2a); a translucent panel (5) having a visible surface (S) facing an observer (B) and a back surface (R) facing away from the observer (B); a light guide body (4) arranged such that its optical coupling exit surface (4b) is adjacent to the back surface (R) of the panel (5) via a first air gap (7), wherein the light guide body (4) has an optical coupling inlet surface (4a) arranged laterally relative to the optical coupling exit surface (4b) and a reflective surface (4c) opposite to the optical coupling exit surface (4b); and a light guide member (3) having a light-inlet surface (3a) facing the light source assembly (2) and a light-inlet surface (4c) facing the light guide body (4). a) The light-emitting surface (3b) spaced apart by the second air gap (8) is used to couple the light (L) of the light source assembly (2) into the light guide body (4) with at least one internal reflection in the light guide (3), wherein the light guide (3) and the light guide body (4) are designed such that the first light coupled into the light guide body (4) is deflected, such as reflected and / or refracted, along the first beam path (I) toward the reflecting surface (4c) so as to be reflected in the direction of the light-emitting surface (4b) by internal reflection at the reflecting surface (4c), and the second light coupled into the light guide body (4) is deflected, such as reflected and / or refracted, along the second beam path (II) toward the light-emitting surface (4b).

Description

Technical Field

[0001] The present invention relates to a light-emitting element, particularly for use in the passenger unit of a motor vehicle. Background Technology

[0002] Light-emitting elements, especially those used to generate ambient light in motor vehicles, typically have a panel that forms a visible surface facing the observer or occupant. For backlighting this surface, multiple light sources, usually composed of light source assemblies, are typically arranged to provide the most uniform possible backlighting to the visible surface. This should be achieved with the lowest possible power input from the light sources, thereby saving energy, construction space, and weight. When the color spectrum of the light emitted by the light sources can be set by controlling the light sources, a problem of insufficient illumination uniformity arises, particularly because this is caused by the color mixing of light sources arranged side-by-side, resulting in a change in the optical path due to the bias towards the visible surface to be backlit, which in turn affects the uniformity of the backlighting. While it is possible to counteract this by using diffusers in the optical path, this in most cases increases the construction space and still affects light transmission efficiency. That is, this involves not only avoiding non-uniformity in the illumination of the visible surface to be backlit but also achieving cost, weight, and construction space savings and improved backlighting efficiency. Summary of the Invention

[0003] In this context, a solution for a light-emitting element is needed, which provides improved uniformity of backlight illumination on the relevant display surface, particularly saving construction space, cost, and weight, without at least affecting efficiency. This objective is achieved by the light-emitting element according to claim 1. Equally advantageous uses are the subject matter of the parallel claims. Advantageous designs are the subject matter of the dependent claims. It should be noted that the features individually detailed in the claims can be combined with each other in any technically meaningful manner and demonstrate other embodiments of the invention. The description, in particular, is appended with the drawings to characterize and describe the invention in detail.

[0004] This invention relates to a light-emitting element having a light source assembly with at least one light source, preferably multiple light sources. In a simple design, the light source assembly includes only one light source, such as a light-emitting diode (LED). The light source can, for example, be selectively activated and / or its light intensity can be adjusted by a control unit. Preferably, the invention relates to a light source in which at least two, more preferably three, light sources differ in the color spectrum of the light they emit, wherein differences within manufacturing tolerances are not considered differences in the color spectrum according to the invention. For example, the invention relates to a light source assembly formed of at least one RGB LED, in which three light sources with different color spectra are combined into a common (e.g., SMD construction) module.

[0005] According to the invention, a translucent panel is also provided, the panel having a visible surface facing the observer and to be backlit, and a back surface facing away from the observer. The term translucent should be considered as a minimum requirement. Therefore, the possibility of the panel being partially opaque or partially translucent should not be excluded. The panel is formed, for example, in one piece or in multiple pieces. The panel preferably has a panel body formed of a transparent material (such as transparent thermoplastic) and a translucent decorative layer forming the visible surface. For example, the decorative layer is a thin metal layer.

[0006] According to the present invention, the light-emitting element has a light-guiding body arranged to abut the back surface of the panel via a first air gap with its optical coupling exit surface. The light-guiding body according to the present invention has an optical coupling inlet surface arranged laterally relative to the optical coupling exit surface and a first reflective surface opposite to the optical coupling exit surface. Preferably, the light-guiding body is formed of transparent thermoplastic, except for an optional additional surface coating.

[0007] According to the present invention, the light-emitting element further comprises a light guide having an incident surface facing the light source assembly and an emitting surface facing the light coupling incident surface of the light guide body, separated by a second air gap, so as to couple the light of the light source assembly into the light guide body during at least one internal reflection in the light guide. The first air gap and the second air gap here are responsible for optical decoupling, so as to prevent the observer from "seeing through" to the light source assembly when viewing.

[0008] According to the present invention, the light guide and the light guide body are designed such that a first light coupled into the light guide body is deflected, such as reflected and / or refracted, along a first beam path by the light guide in the direction toward the reflecting surface, so as to be reflected in the direction of the optical coupling outlet by internal reflection at the reflecting surface, that is, indirectly reaching the panel, while a second light coupled into the light guide body is deflected, such as reflected and / or refracted, along a second beam path by the light guide in the direction toward the optical coupling outlet, so as to directly reach the panel or at least reach the optical coupling outlet of the light guide body.

[0009] This approach of providing multiple light paths for backlighting the visible surface improves the uniformity of backlighting without requiring an additional diffuser in the beam path between the light source assembly and the visible surface of the panel. Thus, uniform illumination of the illuminated surface (regardless of color) can be achieved through the different paths of each beam. Simultaneously, high light output is achieved within a smaller construction space. This also saves on cost, construction space, and weight.

[0010] Preferably, the second light from the second beam path is reflected at the optical coupling outlet of the optical guide body in the direction toward the reflective surface.

[0011] Preferably, the light guide is designed such that the light from the light source assembly is reflected multiple times at the inner interface of the light guide or is reflected at least once at the inner interface of the light guide and refracted as it leaves the light guide, so as to be coupled into the light guide body.

[0012] Preferably, a reflective coating is provided to provide a reflective surface for the light guide body. The reflective coating is, for example, a mirror-like opaque coating, such as a PVD or NCVM coating. However, it is also conceivable that the reflective coating is also applied to a substrate (such as a foil substrate) that is in mate with the base material of the light guide body.

[0013] To avoid light interference, according to a preferred design, a light baffle made of an opaque material is provided between the light source assembly and the observer, more preferably between the panel and the light guide. Preferably, the panel also covers the light baffle.

[0014] Preferably, the panel has a panel body and a transmissive decorative layer applied to or formed on the visible side. Preferably, the decorative layer is a metallic coating, applied as a thin layer, for example, using PVD or NCVM methods. This achieves the reverse reflection of external light from the passenger unit of the motor vehicle, thereby suppressing undesirable optical effects caused by external light penetrating into the panel.

[0015] Preferably, the light guide has a surface microstructured portion for generating internal reflection. For example, it is provided with a vertical microstructured portion. Preferably, the plane normals of a single independent surface form an angle of 4° to 12°.

[0016] Preferably, the light-emitting surface of the light guide is microstructured. The light-emitting surface may have, for example, microlens-shaped, micropyramid-shaped, or microcolumn-shaped structured portions.

[0017] Preferably, the light guide is configured to guide the light from the light source assembly to the light coupling surface of the light guide body through more than one internal reflection.

[0018] Preferably, the main emission direction of the light source assembly is not aligned with the back of the panel, and the light guide has, for example, the task of achieving a directional deflection of more than 270° in the initial main emission direction of the light source assembly.

[0019] The present invention also relates to the use of the light-emitting element in one of the previously described embodiments in a motor vehicle, particularly as an ambient light source, preferably arranged below the lower edge of the door window or in the dashboard. With the arrangement according to the invention, the observer (in this case, the driver or front passenger) can directly see the visible surface without being affected by undesirable reflections. Attached Figure Description

[0020] The invention is described in detail with reference to the following accompanying drawings. The drawings are to be understood as merely exemplary and form only two preferred embodiments. In the drawings: Figure 1 A cross-sectional view of a first embodiment of the light-emitting element 1 according to the present invention is shown; Figure 2 A cross-sectional view of a second embodiment of the light-emitting element 1 according to the present invention is shown. Specific Implementation This invention relates to a light-emitting element 1, which in a first embodiment... Figure 1The diagram shows a light source assembly 2 with multiple light sources 2a that differ in their respective color spectra. Here, the light source assembly is an RGB light-emitting diode module with an SMD structure applied to a circuit board, whose light sources 2a can be selectively activated and whose light intensity can be adjusted by a control unit (not shown). A translucent panel 5 is also provided on the observer B side, having a visible surface S facing the observer B and a back surface R facing away from the observer. The term translucent should be considered a minimum requirement. Therefore, the possibility of partially opaque or partially translucent panels 5 should not be excluded. Panel 5 can be formed, for example, as a single piece or multiple pieces. In the first embodiment shown, the panel has a panel body 5a formed of a transparent material (such as transparent thermoplastic) and a transmissive decorative layer 5b forming the visible surface S, wherein the decorative layer 5b is a thin metal layer. More precisely, the decorative layer 5b is a metal coating, applied as a thin layer, for example, in PVD or NCVM methods. This enables external light L from the passenger unit of the motor vehicle. The reverse reflection, in order to suppress the negative reflection due to external light L Undesirable optical effects caused by penetration into panel 5, wherein the first air gap 7 is formed for external light L Another reflective barrier.

[0022] The light-emitting element 1 also has a light guide body 4, which is arranged to abut the back surface R of the panel 5 via a first air gap 7 with its optical coupling exit surface 4b. The light guide body 4, provided according to the invention, has an optical coupling inlet surface 4a arranged laterally relative to the optical coupling exit surface 4b and a reflective surface 4c opposite to the optical coupling exit surface 4b. Except for a surface coating 4d, the light guide body 4 is formed of transparent thermoplastic. To provide the reflective surface 4c of the light guide body 4, the light guide body has a reflective coating 4d formed of a mirror-like opaque coating (such as a PVD or NCVM coating). However, it is also conceivable that the reflective coating 4d is also applied to a substrate (such as a foil substrate) that is matingly connected to the base material of the light guide body 4.

[0023] To couple the light L from the light source assembly 2 into the light guide body 4, the light-emitting element 1 also has a light guide 3, which has an incident surface 3a facing the light source assembly 2 and an emitting surface 3b facing the incident surface 4a of the light guide body 4, spaced apart by a second air gap 8. The light guide 3 is configured to couple the light L from the light source assembly 2 into the light guide body 4 after at least one internal reflection within the light guide 2. The first air gap 7 and the second air gap 8 are responsible for optical decoupling, preventing the observer B from "seeing through" to the light source assembly 2 during viewing.

[0024] The light guide 3 and the light guide body 4 are designed such that a first light coupled into the light guide body 4 is deflected, such as reflected and / or refracted, along a first beam path I by the light guide 3 in the direction toward the reflecting surface R, so as to be reflected in the direction of the optical coupling outlet 4b by internal reflection at the reflecting surface 4c, that is, indirectly reaching the panel 5. Simultaneously, a second light coupled into the light guide body 4 is deflected, such as reflected and / or refracted, along a second beam path II by the light guide 3 in the direction toward the optical coupling outlet 4b, so as to directly reach the panel 5 or at least reach the optical coupling outlet 4b of the light guide body 4. Here, the second light along the second beam path II is reflected in the opposite direction toward the reflecting surface 4c at the optical coupling outlet 4b of the light guide body 4.

[0025] In order to refract light in a proper manner, the light-emitting surface 3b of the light guide 3 is microstructured. The light-emitting surface may have, for example, microlens-shaped, micropyramid-shaped, or microcolumn-shaped structured portions.

[0026] This measure of providing multiple light paths for backlighting the visible surface S improves the uniformity of backlighting without requiring an additional diffuser in the beam path between the light source assembly 2 and the visible surface S of the panel 5. Thus, uniform illumination of the illuminated surface (regardless of color) can be achieved through the different paths of each beam. This also saves on cost, construction space, and weight.

[0027] To avoid light interference, a light baffle 6 made of opaque material is provided between the light source assembly 2 and the observer b, or more precisely between the panel 5 and the light guide 3, wherein the panel 5 also covers the light baffle 6.

[0028] Figure 2 The difference between the second embodiment and the first embodiment shown is mainly in the relative arrangement of the light source assembly 2 and the design of the light guide 3. Figure 1 In the first embodiment of the light-emitting element 1 shown, the main emission direction of the light source assembly 2 is aligned with the back surface R of the panel, while... Figure 2 The second embodiment shown is different, and the task of the light guide 3 is to achieve a directional deflection of more than 270° from the initial main emission direction of the light source assembly 2. Therefore, the second embodiment differs further in that the light guide 3 is formed to guide the light from the light source assembly 2 to the light coupling surface 4a of the light guide body 4 via more than one internal reflection. For this purpose, the light guide 3 has a surface microstructured portion 3c for generating internal reflection. For example, a vertical microstructured portion is provided. Preferably, the plane normals of a single independent surface form an angle of 4° to 12°.

Claims

1. A light-emitting element (1), comprising: A light source assembly (2) having at least one light source (2a); A translucent panel (5) having a visible face (S) facing the observer (B) and a back face (R) facing away from the observer (B). A light guide body (4) is arranged to abut the back surface (R) of the panel (5) via a first air gap (7) with its optical coupler exit surface (4b), wherein the light guide body (4) has an optical coupler in surface (4a) arranged laterally relative to the optical coupler exit surface (4b) and a reflective surface (4c) opposite to the optical coupler exit surface (4b). The light guide (3) has an incident surface (3a) facing the light source assembly (2) and an exit surface (3b) facing the light coupling incident surface (4a) of the light guide body (4) and separated by a second air gap (8), so as to couple the light (L) of the light source assembly (2) into the light guide body (4) in the case of at least one internal reflection in the light guide (3). The light guide (3) and the light guide body (4) are designed such that a first light coupled into the light guide body (4) is deflected, such as reflected and / or refracted, along a first beam path (I) by the first light guide (3) in the direction toward the reflecting surface (4c) so as to be reflected to the light output surface (4b) by internal reflection at the reflecting surface (4c), and a second light coupled into the light guide body (4) is deflected, such as reflected and / or refracted, along a second beam path (II) by the light guide (3) in the direction toward the light output surface (4b).

2. The light-emitting element (1) according to the preceding claim, wherein the reflective surface (4c) of the light guide body (4) is formed by a reflective coating (4d).

3. The light-emitting element (1) according to any one of the preceding claims, wherein the light (L) of the light source assembly (2) is reflected multiple times at the inner interface of the light guide (3) or reflected at least once at the inner interface of the light guide (3) and refracted as it leaves the light-emitting surface (3b) of the light guide (3) so as to be coupled into the light guide body (4).

4. The light-emitting element (1) according to any one of the preceding claims, wherein the second light of the second beam path (II) is reflected at the light-coupled surface (4b) of the light guide body (4) in a direction toward the reflecting surface (4c).

5. The light-emitting element (1) according to any one of the preceding claims, wherein a light baffle (6) made of an opaque material is provided between the light source assembly (2) and the observer (B), preferably between the panel (5) and the light guide (3).

6. The light-emitting element (1) according to the preceding claim, wherein the panel (5) further covers the light baffle (6).

7. The light-emitting element (1) according to any one of the preceding claims, wherein the panel (5) has a panel body (5a) and a transmissive decorative layer (5b) applied to or forming the visible surface (S) on one side of the visible surface (S).

8. The light-emitting element (1) according to the preceding claim, wherein the decorative layer (5b) is a metal coating.

9. The light-emitting element (1) according to any one of the preceding claims, wherein the light source assembly (2) comprises at least two, preferably three, light sources (2a) with different color spectra.

10. The light-emitting element (1) according to any one of the preceding claims, wherein the light guide (3) has a surface microstructured portion (3c) for generating internal reflection.

11. The light-emitting element (1) according to any one of the preceding claims, wherein the light-emitting surface (3b) of the light guide (3) is microstructured.

12. The light-emitting element (1) according to any one of the preceding claims, wherein the light guide (3) is formed to guide the light of the light source assembly (2) to the light coupling surface (4a) of the light guide body (4) by more than one internal reflection.

13. The light-emitting element (1) according to any one of the preceding claims, wherein the main emission direction of the light source (2a) of the light source assembly (2) is not aligned with the back surface (R) of the panel (5).

14. Use of the light-emitting element (1) according to any one of the preceding claims in a motor vehicle.

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