Lighting device for motor vehicles

Abstract

Lighting device for motor vehicles with a plurality of light sources (1) and an optical unit upstream of them, by means of which the light (8) emitted by the light source (1) is guided and coupled out according to a predetermined light function, wherein the optical unit has a planar light guide element (22) with two opposing flat sides (10, 11) and with two opposing curved narrow sides (5, 12), wherein the first narrow side (5) of the planar light guide element (22) facing the light sources (1) is designed as a light coupling side (5) for coupling in the light emitted by the light sources (1), and wherein the coupled light (8) is totally internally reflected at the opposing flat sides (10, 11) for light guidance towards a light coupling surface, wherein the coupled light (8) is coupled out at the second narrow side of the planar light guide element (22) forming the light coupling surface.wherein the planar light guiding element (22) on the light coupling side has a number of light coupling segments (23) each assigned to one of the light sources (1), characterized in that , - each light source (1) is arranged on a flat end surface of the associated light coupling segment (23), - the light coupling segments (23) taper towards their flat end surface, - the tapered area of ​​the light coupling segments (23) has a parabolic or a free-surface essentially parabolic contour in cross-section, - in some of the light coupling segments (23) there are slots (24) between the individual light coupling segments (23), wherein the slots (24) taper to a point in the main emission direction (3) of the light sources (1), and wherein the slots (24) of adjacent light coupling segments (23) are arranged next to each other when viewed perpendicular to the main emission direction (3).

Description

[0001] The invention relates to a lighting device according to the preamble of claim 1.

[0002] From EP 1 033 526 A2, a lighting device for motor vehicles is known, comprising a light source and an optical unit, wherein the optical unit has a plurality of rod-shaped light guide elements arranged side by side. Each rod-shaped light guide element has an LED light source at one end, which couples light in from a first narrow side of the respective rod-shaped light guide element. The coupled-in light is totally reflected at the lateral surface of the rod-shaped light guide elements. Because a rear side of the lateral surface is provided with prism-shaped optical elements, the coupled-in light is coupled out on an opposite front side. Using individual rod-shaped light guide elements results in linear illumination, while using several rod-shaped light guide elements arranged side by side results in area illumination.A disadvantage of the known lighting device is that the prismatic optical elements on the back of the rod-shaped light guide elements limit the luminaire's contour. These prismatic optical elements on the back must be aligned according to the desired light emission direction. In particular, achieving an arc-shaped or wave-shaped luminaire contour is difficult.

[0003] From DE 102 07 694 A1, a lighting device for motor vehicles is known, comprising a light source and an optical unit, wherein the optical unit includes a planar light guide element. A number of row-arranged LED light sources are arranged on a first narrow side of the planar light guide element, and their emitted light is coupled into the planar light guide element via this first narrow side. The planar light guide element has opposite flat sides at which the coupled-in light is totally reflected and directed in a plane of extension of the planar light guide element. A plurality of prism-shaped optical elements are arranged on a flat side located at the rear of the lighting device in the main emission direction, such that the coupled-in light incident on this side is deflected towards a front flat side and coupled out at the same side.The prism-shaped optical elements are arranged such that homogeneous light emission occurs from the front flat surface of the planar light guide element. The front flat surface thus serves as a relatively large light extraction area, acting like a "light curtain" to enable planar light emission. The luminance or illuminance of the planar light guide element is relatively low, so that the planar light guide element can only be used to generate a taillight or side marker light function.

[0004] The subsequently published DE 10 2007 057 399 A1 discloses a lighting device with parabolically contoured light coupling segments. No adjoining slots are provided.

[0005] From DE 102 31 326 A1 a lighting device with a planar light guide element is known, wherein the planar light guide element has light guide bodies assigned to each light source, each of which has parabolic lateral surfaces which converge to form a light disk at a light exit side.

[0006] From DE 10 2006 032 373 A1, a lighting device is known comprising a light source and an optical unit including a planar light-guiding element. The flat sides of the planar light-guiding element serve, on the one hand, for total internal reflection of the light and, on the other hand, as design surfaces for additional light emission. The planar light-guiding element has a light-input surface facing the light source and, on an opposite side, a light-output surface from which the light totally reflected from the flat sides can exit.

[0007] The object of the present invention is to further develop a lighting device for motor vehicles comprising a planar light guiding element in such a way that an extended selection of lighting contours is provided in a simple manner, whereby a relatively homogeneous illumination of a light output surface of the lighting device is achieved.

[0008] To solve this problem, the invention has the features of claim 1.

[0009] A particular advantage of the invention is that the lighting device according to the invention enables a multitude of differently shaped narrow light bands or illuminating contours by means of at least one planar light-guiding element. In particular, any linear light emission surface can be formed, whereby the width of this linear light emission surface can be relatively small or homogeneous illumination can be achieved at the light emission surface. A homogeneous light emission along the "light band" can be achieved by means of a predetermined depth of the planar light-guiding element. The styling possibilities of a lighting device can thus be expanded, since the illuminating contour can be arc-shaped or C-shaped, circular, elliptical, curved, wavy, and in particular closed.The basic concept of the invention is to couple light coupled into the planar light guide element at a rear narrow side and to decouple it at a front narrow side, with the flat sides of the planar light guide element essentially serving to guide the light towards the front narrow side. This results in a planar light guide element with a depth corresponding to the direction of light guidance. According to the invention, the planar light guide element has light coupling segments in a light coupling area facing the light sources, which have a parabolic or free-form contour. Advantageously, this allows for light guidance or direction, enabling a relatively strong signal light function such as brake light, reversing light, rear fog light, turn signal, or daytime running light.

[0010] According to a preferred embodiment of the invention, a first flat side and a second flat side of the planar light guide element are planar and parallel to each other in the main emission direction, with both flat sides maintaining a constant distance from each other. Advantageously, this gives the planar light guide element a preferred orientation that runs parallel to the main emission direction or parallel to the longitudinal axis of the vehicle. Thus, the planar light guide element is arranged in a relatively space-saving manner within the housing of the lighting device, allowing for the arrangement of a further lighting unit in a rearward region of the housing in the main emission direction to generate an additional lighting function. If the planar light guide element has a closed or open orientation perpendicular to the main emission direction, it can, for example, be arranged coaxially to a further lighting unit.If the planar light guide element has a flat path, it can be arranged adjacent to another lighting unit.

[0011] According to a further development of the invention, the planar light-guiding element has a depth extending between a light-input surface and a light-output surface of the same, which is at least five times the distance between the first and second flat sides of the planar light-guiding element. Preferably, the depth is ten times the distance. Advantageously, this depth extension of the planar light-guiding element in the main emission direction allows sufficient "mixing" of the coupled light within the planar light-guiding element, so that homogeneous illumination at the light-output surface is achieved. Furthermore, the lighting device, for example with a crystal-clear cover plate, acquires a spatial character or stylistic feature determined by the shape of the light-guiding element.

[0012] According to a further development of the invention, the first flat side and the second flat side of the planar light-guiding element are planar and run perpendicular to the main light emission direction. The planar light-guiding element can be composed of several integrally connected planar light-guiding segments, ensuring a continuous linear light-emitting surface of the light-guiding segments. Advantageously, this allows for a wide range of stylistic requirements regarding luminaire contouring to be met.

[0013] The light guide can also be advantageously used to accommodate components of other lighting units.

[0014] According to a further development of the invention, the LED lighting elements are arranged oriented in the direction of a normal to the planar light coupling surface. An optical axis of the LED lighting elements is thus perpendicular to the light coupling surface. Advantageously, the planar light guide element can be used to emit light for a taillight, side marker light, or position light function.

[0015] Further advantages of the invention will become apparent from the further dependent claims.

[0016] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings.

[0017] They show: Fig. 1 a top view of a lighting device with a plurality of LED lighting elements and a front-mounted planar light guide element as an optical unit, Fig. 2 a vertical section through the lighting device along section line II - II in Fig. 1 without drawn light rays, Fig. 3. Make a vertical section through the lighting device along section line II - II in Fig. 1 with light rays shown, Fig. 4. A top view of the lighting device - as shown in Fig. 1 - , where light beams emitted by some light sources are shown, Fig. 5 a top view of a lighting device according to a second embodiment with parabolic light coupling segments of the planar light guiding element assigned to each light source, Fig. 6 a top view of a lighting device according to a third embodiment with parabolic light coupling segments of the planar light guide element assigned to each light source, wherein the light coupling segments are extended in the main emission direction as a result of incisions, Fig. 7 a vertical section through a lighting device according to a fourth embodiment, wherein a first light unit with the planar light guiding element for generating a first light function and a second light unit with a reflector as a reflector unit for generating a second light function are arranged parallel in the vertical direction and Fig. 8 a schematic front view of a lighting device seen opposite the main direction of emission.

[0018] A lighting device for vehicles is preferably arranged in a rear area of ​​the motor vehicle and serves to generate a signal function such as brake light, flashing light, daytime running light, tail light, side marker light or position light function.

[0019] According to a first embodiment of the invention according to the Fig. In a housing (not shown), a light source unit with a plurality of light sources 1 and an optical unit with a planar light guide 2 are provided in sections 1 to 4. In the main light emission direction 3, a cover plate 4, for example colored or crystal clear, is positioned in front of the planar light guide 2, typically covering a front opening of the housing (not shown). The light sources 1 are designed as LED light elements arranged at intervals from each other in an arc shape. The LED light elements 1 are assigned to a first narrow side 5 of the planar light guide 2, which serves as a light coupling surface. The LED light elements 1 are designed as side-mounted LED light elements arranged on a common circuit board 6 that runs parallel to the extent of the planar light guide 2.

[0020] As from the Fig. 2 and Fig. As can be seen in Figure 3, a principal axis 7 of the housing of the side-mounted LED lighting element 1 runs perpendicular to the circuit board 6 or the plane of extension of the planar light guide element 2, wherein the light 8 emitted by the side-mounted LED lighting elements 1 is emitted laterally in the direction of the light coupling surface 5. The light coupling surface 5 is planar, with an optical axis 9 of the side-mounted LED lighting element 1 forming a normal to the light coupling surface 5 of the planar light guide element 2. Optionally, the planar light guide element 2 may have support ribs (not shown) for guidance on the circuit board 6. Preferably, the circuit board 6 and the planar light guide element 2 are attached laterally to the housing of the lighting device (not shown).

[0021] The planar light-guiding element 2 has a first flat side 10 (upper) and a second flat side 11 (lower) extending parallel to each other at a constant distance A from the first narrow side 5 to an opposite second narrow side 12. The first flat side 10 and the second flat side 11 are flat and free of optics, i.e., smooth, so that the coupled light 8 is totally reflected at them and guided towards the second narrow side 12. Side surfaces 16 extend along the edges of the first flat side 10 and the second flat side 11, preferably perpendicular to the rear narrow side 5 and / or the front narrow side 12.

[0022] As especially from Fig. As can be seen in Figure 3, the second narrow side 12 serves as the light extraction surface of the planar light guiding element 2, from which the light 8 is emitted in the main light emission direction 3 at a scattering angle. The light extraction surface 12 can be provided with cylindrical or pincushion-shaped scattering optic elements 13 – see Figure 3. Fig. 1 -, so that an adjustment can be made with regard to the requirements for the homogeneity of the illumination. If necessary, the second narrow side 12 can also be free of diffusing optical elements 13.

[0023] According to an embodiment of the invention (not shown), an additional disc, which is frosted and / or translucent and / or colored, can be arranged between the cover disc 4 and the second narrow side 12 of the planar light-guiding element 2. Advantageously, in this embodiment, the additional light-guiding disc can be backlit as a "glowing body" by means of the planar light-guiding element.

[0024] The planar light-guiding element 2 extends horizontally in an arc perpendicular to the main light emission direction 3, with the first narrow side 5 and the second narrow side 12 running parallel to each other. The front second narrow side 12 defines the illuminated contour. It is a linear illuminated contour that extends horizontally in an arc. The flat sides 10, 11 adjoining the front narrow side 12 extend horizontally and in a plane. Alternatively, the first flat side 10 and the second flat side 11 can also extend in an arc perpendicular to the main light emission direction 3, see [reference]. Fig. 8.

[0025] According to an alternative embodiment, the planar light guiding element 2 can also extend in a vertical direction.

[0026] As from the Fig. 2 and Fig. As can be seen in Figure 3, the planar light-guiding element 2 has a depth T which, in the present embodiment, is ten times greater than the thickness of the light-guiding element 2 formed by the distance A between the first flat side 10 and the second flat side 11. For example, the depth T between the light-input area 5 and the light-output area 12 can be at least five times greater than the distance A between the flat sides 10 and 11. In the present embodiment, the distance A = 4 mm and the depth T = 40 mm.

[0027] As from Fig. As can be seen in Figure 4, two light cones 14 of the coupled light 8 are formed in the planar light guiding element, wherein the light of the first light cone 14' is formed by a first light source 1' and the light of a second light cone 14'' by a second light source 1''. These are shown by way of example in Fig. Figure 3 shows that the light cones 14 of adjacent light sources 1 overlap within the planar light guide element 2, or at least on the front narrow side 12, to form illuminating zones, thus providing illumination on the front narrow side 12. A distance s between adjacent LED illuminating elements 1 is dimensioned according to the depth T of the light guide element 2 such that a corresponding overlap of the illuminating zones can occur.

[0028] The planar light guiding element 2 according to the Fig. 1 to 4 is preferably used to generate a less strong signal function such as a tail light, side marker or position light function.

[0029] According to an alternative embodiment not covered by the patent claims, as described in the Fig. In contrast to the light unit of the first embodiment, embodiment 5 provides a planar light guide element 20 which has parabolic or free-form light coupling segments 21 in a light coupling area, each of which is assigned a single light source 1. Advantageously, the illuminance or light intensity can be increased to such an extent by forming light coupling segments 21 on the light coupling side of the planar light guide element 20 that the light unit can be used to generate a brake light, turn signal, reversing light, or daytime running light function.

[0030] According to a further embodiment of a light unit according to the Fig. 6 can have a planar light guiding element 22 parabolic or free-area light coupling segments 23, which, in contrast to the light coupling segments 21 according to the planar guiding element 20, Fig. 5 additionally have incisions or slots 24. This allows the light guiding effect on the coupling side to be further improved, so that brighter light functions can be generated.

[0031] In the exemplary embodiments according to Fig. 5 and Fig. The light sources 1 are each parallel to each other and aligned in the main light emission direction 3. The light coupling surfaces 5 assigned to each light source 1 are arranged parallel to each other.

[0032] According to a further embodiment not covered by the patent claims, as described in the Fig. In the first lighting unit 25, a number of parallel, planar light guide elements 26, 27 and their respective light sources 1 are formed by a number of parallel, planar light guide elements 26, 27 and their respective coupling sides. A second lighting unit 28 is arranged between the horizontally arranged light guide elements 26, 27, which are positioned at a predetermined distance from one another. This second lighting unit comprises a number of light sources 29 and their respective reflectors 30. The second lighting unit 28 can, for example, be used to generate a brake light function, while the first lighting unit 25 is used to generate a tail light function. The light sources 29 of the second lighting unit 28 are identical in design to the light sources 1 of the first lighting unit 25. The light sources 1, 29 are arranged on a common circuit board 31, which extends transversely to the main light emission direction 3. This embodiment of the lighting device advantageously has a space-saving design.

[0033] According to a further embodiment not covered by the patent claims, as described in the Fig.8. A lighting device with a first lighting function can be formed, which is composed of a plurality of planar light-guiding elements 35, 36, 37, 38. The planar light-guiding elements 35, 36, 37, 38 are shaped such that they form an arc-shaped illuminating contour at the light-outlet side. The planar light-guiding elements 35, 36, 37, 38 each have side surfaces 35' or 35'', 36' or 36'', 37' or 37'', 38' or 38'', respectively, wherein the side surface 35'' is arranged directly adjacent to a central region (lower flat side) of the light-guiding element 36 and a first end 35' is open. A first side surface 36' of the second light-guiding element 36 abuts directly against a first end 37' of the third light-guiding element. A first end 38' of the fourth light guide element 38 lies against a lower flat side of the third light guide element 37 and a second end 38'' of the light guide element 38 lies against a side surface 37'' of the light guide element 37.The invention thus enables a wide variation of illumination contours, wherein the light-guiding elements 35, 36, 37, 38 can each have straight and arc-shaped light-guiding segments. This results in an illumination contour structure that can have closed and / or open lines. A continuous light contour is formed because the side surfaces of the light-guiding elements can directly abut flat sides or side surfaces of other light-guiding elements.

[0034] According to an embodiment of the invention not shown, the light output surface of the planar light guide element 12 can have an eroded or etched structure.

[0035] Identical components or component functions of the exemplary embodiments are provided with the same reference numerals.

[0036] According to an alternative embodiment of the invention (not shown), the first flat surface 10 and / or the second flat surface 11 of the planar light-guiding element can be provided with extraction means, such as optical surfaces, frosting, optical structuring, or printing, so that a small portion of the coupled-in light is extracted at at least one of the flat surfaces 10, 11. In particular, one flat surface 10, 11 is partially provided with optical elements, so that a small portion of the coupled-in light serves to visualize the flat surface at which the light is extracted. Advantageously, this can create a three-dimensional appearance of the planar light-guiding element.

[0037] According to an alternative embodiment not shown, the flat sides 10, 11 can also be arranged antiparallel, with the first flat side being arranged at an angle to the second flat side.

[0038] According to a further embodiment of the invention, the light coupling surface 5 of the planar light guiding element 2, 20, 26, 35, 36, 37, 38 can also be designed as an optical surface for light coupling, for example it can be spherical or cylindrical.

[0039] According to a further embodiment of the invention, the at least one planar light guide element together with the associated light sources forms a first lighting unit, for example the planar light guide elements can be arranged at such a distance from each other that a second lighting unit can be positioned between them with a reflector extending between the light guide elements and a light source located behind in the main direction of emission to form a further lighting function.

Claims

[1] Lighting device for motor vehicles with a plurality of light sources (1) and an optical unit upstream of them, by means of which the light (8) emitted by the light source (1) is guided and coupled out according to a predetermined light function, wherein the optical unit has a planar light guide element (22) with two opposing flat sides (10, 11) and with two opposing curved narrow sides (5, 12), wherein the first narrow side (5) of the planar light guide element (22) facing the light sources (1) is designed as a light coupling side (5) for coupling in the light emitted by the light sources (1), and wherein the coupled light (8) is totally internally reflected at the opposing flat sides (10, 11) for light guidance towards a light coupling surface, wherein the coupled light (8) is coupled out at the second narrow side of the planar light guide element (22) forming the light coupling surface becomes,wherein the planar light guiding element (22) on the light coupling side has a number of light coupling segments (23) each assigned to one of the light sources (1), characterized by , that - each light source (1) is arranged on a flat end surface of the associated light coupling segment (23), - the light coupling segments (23) taper towards their flat end surface, - the tapered area of ​​the light coupling segments (23) has a parabolic or a free-surface essentially parabolic contour in cross-section, - in some of the light coupling segments (23) there are slots (24) between the individual light coupling segments (23), wherein the slots (24) taper to a point in the main emission direction (3) of the light sources (1), and wherein the slots (24) of adjacent light coupling segments (23) are arranged next to each other when viewed perpendicular to the main emission direction (3). [2] Lighting device according to claim 1, characterized by , that the flat sides (10, 11) of the planar light guiding element (22) are designed without optics, such that the coupled light (8) is exclusively totally reflected at the flat sides (10, 11). [3] Lighting device according to claim 1 or 2, characterized by , that a first flat side (10) and a second flat side (11) of the planar light guiding element (22) are arranged at a constant distance (A) from each other. [4] Lighting device according to any one of claims 1 to 3, characterized by , that the first flat side (10) and the second flat side (11) run parallel in the main light emission direction (3). [5] Lighting device according to any one of claims 1 to 4, characterized by , that the first flat side (10) and the second flat side (11) run horizontally and / or vertically in the main light emission direction (3). [6] Lighting device according to any one of claims 1 to 5, characterized by , that the first flat side (10) and the second flat side (11) run perpendicular to the main direction of light emission (3). [7] Lighting device according to any one of claims 1 to 6, characterized by , that the planar light guiding element (22) has a depth extending between the light coupling surface (5) and the light coupling surface (12) which is at least five times as large as the distance (A) of the first flat side (10) to the second flat side (11). [8] Lighting device according to any one of claims 1 to 7, characterized by , that a plurality of LED light elements arranged along the same and spaced apart from each other are assigned as light sources (1) to the light coupling side of the planar light guiding element (22), whose optical axis (9) is each oriented normal to the light coupling surface (5). [9] Lighting device according to any one of claims 1 to 8, characterized by , that the light output surface (12) of the planar light guiding element (22) has scattering optic elements (13). [10] Lighting device according to any one of claims 1 to 9, characterized by , that a frosted or translucent additional light disc is arranged between the planar light guiding element (22) and a cover disc covering an opening of the housing of the lighting device.

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