Lighting device for vehicles

Abstract

The invention relates to a lighting device for vehicles with a first lighting unit (1) for generating a first lighting function and with a second lighting unit (2) for generating a second lighting function, wherein the first lighting unit (1) has a flat light guide (3) with opposing flat sides (4, 4') at which coupled light (L1) is totally reflected in a light guiding direction (19) within the flat light guide (3), and with a narrow side (5') connecting the flat sides (4, 4') at which light (L1) generated by the light source (6, 8) can be coupled into the flat light guide (3), wherein the second lighting unit (2) is arranged behind the first lighting unit (1) in the main emission direction (H), wherein light (L2) emitted by the second lighting unit (2) passes through the flat sides (4, 4') of the flat light guide (3) and is emitted in the main emission direction (H).wherein the second illuminating unit (2) is arranged in projection to a normal (N) of the flat light guide (3) in an edge region (15) of the same and / or outside the edge region (5) of the same, such that the second illuminating unit (2) has optical means (12) such that the light (L2) generated by a light source (8) of the second illuminating unit (2) passes through a light transmission area (20) of the flat light guide (3) which is larger than 50% of a total area of ​​the flat light guide (3).

Description

[0001] The invention relates to a lighting device for vehicles with a first lighting unit for generating a first lighting function and with a second lighting unit for generating a second lighting function, wherein the first lighting unit has a flat light guide with opposite flat sides on which coupled light in a light guiding direction is totally reflected within the flat light guide, and with a narrow side connecting the flat sides on which light generated by the light source can be coupled into the flat light guide, wherein the second lighting unit is arranged behind the first lighting unit in the main emission direction, wherein light emitted by the second lighting unit passes through the flat sides of the flat light guide and is emitted in the main emission direction.

[0002] From DE 10 2023 108 470 A1, a lighting device for vehicles is known, comprising a flat light guide with opposing, parallel flat sides and narrow sides connecting these flat sides. A light source is arranged on one narrow side, so that light is coupled into the flat light guide at this narrow side. This coupled light is then transmitted along the opposite flat sides of the flat light guide in the direction of light emission by total internal reflection. The flat light guide has a micro-optical structure on a flat side leading in the main emission direction, so that the coupled light is scattered and coupled out at this front flat side. A reflective surface is arranged on the rear side of the flat light guide, so that light coupled out at the rear can be reflected back and used for the lighting function.

[0003] From DE 10 2013 105 153 A1, a lighting device for vehicles is known, comprising a first lighting unit for generating a first lighting function and a second lighting unit for generating a second lighting function. The first lighting unit has a flat light guide with opposing flat sides and narrow sides connecting the opposing flat sides. Light is coupled into one narrow side of the flat light guide and totally reflected at the flat sides of the flat light guide in the direction of light transmission. In certain areas, the flat light guide has output coupling elements on its rear flat side in the main emission direction, so that coupled light striking these elements is deflected towards a front flat side serving as a light output surface, allowing it to exit the flat light guide. These output coupling elements are arranged in several spaced-apart sections of the rear flat side.Between these sections, sections free of coupling are provided, which serve as light transmission sections for the passage of light generated by the second lighting unit. The second lighting unit is arranged behind the flat light guide in the main emission direction and can include a light source and a reflector. A disadvantage of the known lighting device is that, due to its arrangement behind the flat light guide, the second lighting unit is visible to an observer from the outside. Furthermore, the luminous efficacy of the second lighting unit is limited because some of the emitted light is absorbed at the sections on the rear flat side of the flat light guide that are equipped with coupling elements.

[0004] US Patent 2024 / 0310015A1 discloses a vehicle lighting device in which a light guide with flattened coupling elements is arranged within the field of view of a main light module, so that its light can pass through almost undisturbed.

[0005] The object of the present invention is therefore to further develop a lighting device for vehicles in such a way that several lighting functions are provided, whereby a homogeneous and planar light emission surface is formed with a homogeneous appearance.

[0006] To solve this problem, the invention in conjunction with the preamble of claim 1 is characterized in that the second lighting unit is arranged in projection to a normal of the flat light guide in an edge region of the same and / or outside the edge region of the same, and that the second lighting unit has optical means such that the light generated by a light source of the second lighting unit passes through a light transmission area of ​​the flat light guide which is larger than 50% of a total area of ​​the flat light guide.

[0007] The particular advantage of the invention lies in the fact that a light-emitting surface with a homogeneous appearance is provided for both a first and a second lighting function, free from illuminated sections with differing light patterns. The basic concept of the invention is to utilize coupled light from a flat light guide for a first lighting function on the one hand, and the backlighting of the flat light guide across a closed and continuous surface for generating a second lighting function on the other. The flat light guide has a homogeneous structure and / or a uniform surface across its entire area (front and rear flat surfaces), resulting in a homogeneous appearance of the illuminated surface.The same surface sections or areas of the flat light guide thus serve for the transmission of light refracted at the flat light guide (generation of the second light function) and for the extraction of totally reflected light (generation of the first light function).

[0008] According to a preferred embodiment of the invention, the majority of the flat light guide surface is used for generating the first and second light functions. Preferably, a light transmission area for generating the second light function on a rear flat side of the flat light guide is smaller than a total internal reflection area of ​​the rear flat side, so that the total illuminated area of ​​the first light function is larger than that of the second light function.

[0009] According to a further development of the invention, the angle of incidence of the light emitted by the second light function onto the rear flat surface of the flat light guide is smaller than the critical angle of total internal reflection. This ensures that all the light emitted by the second light unit passes through the flat light guide and can be used to generate the second light function.

[0010] According to a further development of the invention, an optical element of the second lighting unit is designed such that the light emitted by the second lighting unit passes onto a single light-transmitting surface of the flat light guide. The light-transmitting surface is thus closed or continuous, so that a uniform appearance of the second lighting function is produced.

[0011] According to a further development of the invention, the flat light guide has no micro-optical elements or coupling elements. The light from the first lighting unit is thus coupled out solely due to total internal reflection at the rear flat surface and refraction at the front flat surface.

[0012] According to a further development of the invention, to increase the homogeneity of the illuminating surface for generating the first and second light functions, for example, the front flat side of the flat light guide can have optics with diverging optical elements. These diverging optical elements are evenly distributed over the entire surface of the front flat side of the flat light guide, so that the overall homogeneous appearance is maintained.

[0013] According to a further development of the invention, the optical element of the second lighting unit has such a width and / or such a minimum distance to the flat light guide that the light deflected by the optical element of the second lighting unit strikes at least 50% of the total area of ​​the flat light guide. This ensures that a relatively large area of ​​the flat light guide can be used for the light transmission of the second lighting unit.

[0014] According to a further development of the invention, the optical element of the second lighting unit is arranged in a first opening of a glazing wall, and an edge region of the flat light guide facing the light source of the first lighting unit is arranged in a second opening of the same glazing wall. This ensures that the light sources of the first and second lighting units, as well as the optical element of the second lighting unit, are concealed. Only the flat light guide is visible to an observer from the outside.

[0015] According to a further development of the invention, the optical element is designed as a Fresnel optical element with a plurality of prisms, which can be arranged flatly in the first opening of the diaphragm wall. Advantageously, this allows for homogeneous light deflection towards the flat light guide.

[0016] In a further development of the invention, the light sources of the first and second lighting units are arranged on a common circuit board, which is concealed by the glare shield. This advantageously allows for cost-effective and material-saving light generation.

[0017] According to a further development of the invention, the flat light guide is designed to be light-transparent and / or crystal clear. Since the flat light guide projects into a cavity of a housing of the lighting device, a lighting device with depth effect is created.

[0018] According to a preferred embodiment of the invention, the first lighting unit serves to generate a taillight function. The second lighting unit serves to generate a brake light function, wherein, when the brake light function is activated, both the light sources of the first and the second lighting units are switched on. The second lighting unit serves as a light amplifier for the first lighting unit, whereby the same color can be used for both lighting functions.

[0019] According to a further development of the invention, the flat light guide projects into a cavity in the housing of the lighting device, which is surrounded or bounded by the glare shield, a design diaphragm arranged essentially behind the flat light guide, and a transparent cover plate arranged in front of the flat light guide. Advantageously, this gives the lighting device a three-dimensional appearance.

[0020] Further advantages of the invention will become apparent from the further dependent claims.

[0021] An embodiment of the invention is explained in more detail below with reference to the drawing.

[0022] The figure shows a schematic cross-section through a lighting device.

[0023] A lighting device according to the invention can be arranged in a rear or front area of ​​a vehicle and serves to generate at least two lighting functions.

[0024] According to the figure, a first lighting unit 1 is provided for generating a first lighting function and a second lighting unit 2 for generating a second lighting function.

[0025] The first lighting unit 1 has a flat light guide 3 which has opposing flat sides 4, 4' and the same connecting narrow sides 5. At least one of the narrow sides 5' serves as a light coupling surface for light L1 emitted from a light source 6 of the first lighting unit 1.

[0026] For example, several light sources 6 can be arranged in a row and / or in a straight line and / or in an arc on a printed circuit board 7. Preferably, the several light sources 6 are arranged following the contour of the light coupling surface 5' of the flat light guide 3. If the flat light guide 3 is flat with a straight light coupling surface 5, the light sources 6 are also arranged in a straight line at a predetermined distance from each other.

[0027] The flat light guide 3 is designed to be light-transparent and / or crystal clear. It is definitely translucent to allow backlighting.

[0028] The second lighting unit 2 is arranged behind the first lighting unit 1 in a main emission direction H of the lighting device. The second lighting unit 2 comprises a number of light sources 8, which are preferably arranged on the same circuit board 7 as the light sources 6 of the first lighting unit 1. In the present embodiment, the circuit board 7 is flat, so that the light sources 8 of the second lighting unit 2 are arranged offset from the light sources 6 of the first lighting unit 1 opposite to the main emission direction H.

[0029] The axes A of the light source 6 of the first lighting unit 1 and the light source 8 of the second lighting unit 2 run perpendicular to a normal N of the flat light guide 3.

[0030] The circuit board 7 is covered by an opaque glare shield 9, wherein a first opening 10 is provided for the passage of light L2 emitted by the light source 8 of the second lighting unit 2 and a second opening 11 for the passage of light L1 emitted by the light source 6 of the first lighting unit 1.

[0031] In the first opening 10 of the baffle 9, a Fresnel optical element 12, comprising a plurality of prisms (not shown), is positioned as an optical element of the second lighting unit 2. In the present embodiment, the Fresnel optical element 12 extends perpendicular to the axis A of the light source 8 and parallel to the normal N of the flat light guide 3.

[0032] In the main emission direction H behind the first lighting unit 1 and the second lighting unit 2, a rear wall 13 of a design baffle 14 extends, which curves from a rear area of ​​the baffle 9, enclosing an edge area 15 of the flat light guide 3 that has the narrow sides 5 not assigned to the light source 6, so that the baffle 9 and the design baffle 14 form a pot-shaped housing. An opening of this housing is closed by a transparent cover plate 16. Only the flat light guide 3 projects into a cavity 17 formed by the housing (baffle 9 and design walls 14) and the cover plate 16.

[0033] The second lighting unit 2 does not project into the cavity 17. In the present embodiment, the second lighting unit 2, with its optical element 12, is set back in the main emission direction H towards an edge region 18 of the flat light guide 3 facing the light source 6. The optical element 12 is thus arranged in the edge region 18 of the flat light guide 3 in projection to the normal N of the flat light guide 3.

[0034] According to an alternative embodiment of the invention (not shown), the light source of the second lighting unit 2 could be arranged on a separate circuit board, such that the light source of the second lighting unit 2 and the optical element 12 are arranged further back from the glare shield 9 compared to the figure. In such an embodiment, the second lighting unit 2 or the optical element 12 would be arranged outside the edge region 18 in projection to the normal N of the flat light guide 3.

[0035] According to a further embodiment of the invention, not shown, the optical element 12 can be arranged raised above the baffle 9, projecting beyond the surface of the baffle 9 facing the cavity 17. However, a portion of the optical element 12 is always arranged within the first opening 10. The edge region 18 of the flat light guide 3 facing the light source 6 of the first lighting unit 1 is therefore not limited to the arrangement within the second opening 11, but can extend into the cavity 17. This would also be the case if, for example, the light source 6 of the first lighting unit 1 were arranged within the second opening 11 of the baffle 9.

[0036] The light L1 generated by the light source 6 of the first lighting unit 1 is coupled into the flat light guide 3 at the coupling surface 5' and is guided by total internal reflection in a light guidance direction 19 via a front flat side 4 and a rear flat side 4' of the flat light guide 3.

[0037] According to a first embodiment of the invention, the flat light guide 3 has scattering optical elements, for example on the front flat side 4 or the rear flat side 4' or within the flat light guide 3. This allows the coupled light to be deflected more precisely and / or a scattering of the light coupled out of the flat light guide 3 to be generated. This scattering effect can also be used to generate the light function produced by the second lighting unit 2 when the light from the second lighting unit 2 passes through the flat light guide 3.

[0038] The optical means 12 is configured such that the light L2 generated by the light source 8 of the second lighting unit 2 is deflected at an acute angle towards the flat light guide 3, which is arranged in the main emission direction H in front of the second lighting unit 2. The light L2 deflected by the optical means 12 strikes a light transmission area 20 of the flat light guide 3, which is larger than 50% of the total area of ​​the flat light guide 3. The light transmission area 20 is formed by a section of the rear flat side 4' of the flat light guide 3 that is smaller than the total area of ​​the rear flat side 4'. The light transmission area 20 has a minimum area that is larger than 50% of the area of ​​the rear flat side 4'. Preferably, the light transmission surface 20 has an area that is larger than 75%, and in particular larger than 80%, of the total area of ​​the flat light guide 3 or the total area of ​​the rear flat side 4' of the flat light guide 3.

[0039] A distance a between the first opening 10 and the second opening 11 of the baffle 9 or the optical element 12 to the flat light guide 3 is chosen to be such that the light beam L2 deflected by the optical element 12 strikes the intended light transmission surface 20 of the flat light guide 3. The further the optical element 12 is from the flat light guide 3, the larger the area of ​​the rear flat surface 4' that is backlit by the second lighting unit.

[0040] Furthermore, the optical element 12 has a width B, or extension perpendicular to the flat light guide 3, such that the deflected light L2 strikes the rear flat surface 4' of the flat light guide 3 at an angle of incidence β1, β2 such that it can pass through the flat light guide 3 by refraction at the rear flat surface 4' and then by refraction at the front flat surface 4 to generate the second light function. The optical element 12 has the minimum width B that ensures that the light rays L2 do not strike the flat light guide 3 at too shallow an angle, which would result in total internal reflection. The angles of incidence β1, β2, or an input angle range of the deflected light L2, are therefore always smaller than a critical angle for total internal reflection at the flat light guide 3.

[0041] As can be seen from the figure, a single closed and continuous light transmission surface 20 of the flat light guide 3 is formed, which is illuminated by the cone-shaped luminous flux L2 of the second lighting unit 2.

[0042] The design panel 14 can, for example, have a black surface. Alternatively, the design panel 14 can also have a reflective surface. It does not contribute to the generation of the light function produced by the second lighting unit 2.

[0043] For example, the first lighting unit 1 can serve to generate a taillight function if the lighting device is located in the rear of the vehicle. For this purpose, the light sources 6 of the first lighting unit 1 can emit red light. The flat light guide 3 can be colored red. Alternatively, it can also be crystal clear. After the light L1 emitted by the light source 6 is coupled into the light coupling surface 5' of the flat light guide 3, total internal reflection occurs at the rear flat side 4' and at the front flat side 4 until the coupled light is coupled out as a light beam L1 at the front flat side 4 (light coupling surface). The light coupling surface can correspond to a portion of the front flat side 4 projecting from the baffle 9.

[0044] To generate a brake light function, the light source 8 of the second lighting unit 2 is additionally switched on, so that after the light beam L2 generated by the second lighting unit 2 passes through the flat light guide 3 in the main emission direction H, a superposition of the first light beam L1 and L2 occurs with a higher illuminance that meets the requirements of the brake light function.

[0045] According to an alternative embodiment of the invention (not shown), the first lighting unit 1 can serve to generate a daytime running light function when the lighting device is located in the front area of ​​the vehicle. The second lighting unit 2 can serve to generate a turn signal function. For this purpose, the light source 8 emits yellow light. To generate the turn signal function, only the light sources 8 of the second lighting unit 2 are switched on, while the light source 6 of the first lighting unit 1 is switched off. The light source 6 of the first lighting unit 1 emits white light. In this embodiment, the flat light guide 3 is crystal clear, so that white light is emitted for the daytime running light function and yellow light is emitted for the turn signal function.

[0046] The light sources 6, 8 of the two lighting units 1, 2 are designed as LED light sources.

[0047] According to an alternative embodiment of the invention, the flat light guide 3 can have no scattering optics elements, so that the surfaces of the rear flat side 4' and the front flat side 4 are flat and smooth. Reference symbol list 1 first lighting unit 2 second light unit 3 flat light guides 4.4' front and rear flat side 5.5' narrow sides 6 light source 7 printed circuit board 8 Light source 9 Blind wall 10 first opening 11 second opening 12 Fresnel optical elements 13 Back panel 14 Design panel 15 Edge area 16 Cover plate 17 Cavity 18 Edge area 19 Light guidance direction 20 Light transmission area H Main radiation direction L1,L2 light N Normal axis AB minimum width a minimum distance

Claims

[1] Lighting device for vehicles comprising a first lighting unit (1) for generating a first lighting function and a second lighting unit (2) for generating a second lighting function, wherein the first lighting unit (1) has a flat light guide (3) with opposing flat sides (4, 4') at which coupled light (L1) is totally reflected in a light guiding direction (19) within the flat light guide (3), and with a narrow side (5') connecting the flat sides (4, 4') at which light (L1) generated by the light source (6, 8) can be coupled into the flat light guide (3), wherein the second lighting unit (2) is arranged behind the first lighting unit (1) in the main emission direction (H), wherein light (L2) emitted by the second lighting unit (2) passes through the flat sides (4, 4') of the flat light guide (3) and is emitted in the main emission direction (H), characterized by , - that the second luminaire unit (2) is arranged in projection to a normal (N) of the flat light guide (3) in an edge region (15) of the same and / or outside the edge region (15) of the same, - that the second illuminating unit (2) has optical means (12) such that the light (L2) generated by a light source (8) of the second illuminating unit (2) passes through a light transmission area (20) of the flat light guide (3) which is larger than 50% of a total area of ​​the flat light guide (3). [2] Lighting device according to claim 1, characterized by , that the light transmission area (20) of the flat light guide (3) is greater than 75%, in particular 80%, of the total area of ​​the flat light guide (3). [3] Lighting device according to claim 1 or 2, characterized by, that the optical means (12) is designed such that the light (L2) emitted by the second illuminating unit (2) strikes a rear flat side (4') of the flat light guide (3) in an angle of incidence range (β1, β2), wherein the angle of incidence range (β1, β2) is smaller than a critical angle of total internal reflection. [4] Lighting device according to any one of claims 1 to 3, characterized by , that the optical means (12) is designed such that the light (L2) emitted by the second luminaire (2) hits a single light transmission surface (20) of the flat light guide (3). [5] Lighting device according to any one of claims 1 to 4, characterized by , that the flat light guide (3) has diffusing optical elements on a front flat side (4) and / or a rear flat side (4') or within the flat light guide (3). [6] Lighting device according to any one of claims 1 to 4, characterized by, that the flat optical fiber (3) does not have any scattering optical elements, in particular no micro-optical elements. [7] Lighting device according to any one of claims 1 to 6, characterized by , that the optical means (12) has such a minimum width (B) and / or extends at such a minimum distance (a) to the flat light guide (3) that the light (L2) deflected by the optical means (12) of the second lighting unit (2) strikes at least 50%, preferably at least 75%, of the total area of ​​the rear flat side (4') of the flat light guide (3). [8] Lighting device according to any one of claims 1 to 7, characterized by , that the optical means (12) is arranged perpendicular to the flat light guide (3). [9] Lighting device according to any one of claims 1 to 8, characterized by, that the optical means (12) is arranged in a first opening (10) of a glare wall (9) and an edge region (18) of the flat light guide (3) is arranged in a second opening (11) of the glare wall (9). [10] Lighting device according to any one of claims 1 to 9, characterized by , that the optical means (12) is designed as a planar Fresnel optical element with a plurality of prisms. [11] Lighting device according to any one of claims 1 to 10, characterized by , that a light source (6) of the first lighting unit (1) and the light source (8) of the second lighting unit (2) are arranged on a common circuit board (7). [12] Lighting device according to any one of claims 1 to 11, characterized by that the flat light guide (3) is designed to be light-transparent and / or crystal clear. [13] Lighting device according to any one of claims 1 to 12, characterized by, that the light source (6) of the first lighting unit (1) and the light source (8) of the second lighting unit (2) are designed as an LED light source emitting red light, and that the light source (6, 8) of the first lighting unit (1) and the second lighting unit (2) can be controlled in such a way that when the light source (6) of the first lighting unit (1) is switched on, a taillight function is produced and when the light sources (6, 8) of the first lighting unit (1) and the second lighting unit (2) are switched on, a brake light function is produced. [14] Lighting device according to any one of claims 1 to 13, characterized by , that in the main emission direction (H) behind the flat light guide (3) a design aperture (14) is arranged which extends forward in the main emission direction (H) encompassing the flat light guide (3) to form a pot-shaped housing of the lighting device. [15] Lighting device according to any one of claims 1 to 14, characterized by , that the flat light guide (3) is essentially arranged in a cavity (17) formed by the pot-shaped housing, wherein an opening of the housing is closed by a transparent cover plate (16).

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