Lighting device, in particular for a motor vehicle

Abstract

A lighting device (2), in particular for a motor vehicle, for the visible representation of at least one ornament (4) is proposed, which comprises: a plurality of light sources (100) for generating light; at least one outer light-guiding section (200) which, with respect to an optical axis (A) of the lighting device (2), is arranged outside a radar coupling surface (402) of at least one radar-transparent section (400) for coupling in radar beams, wherein the at least one outer light-guiding section (200) guides the light generated by the light sources (100) and coupled in via a respective coupling surface (202) from a respective light coupling surface (202 into the at least one radar-transparent section (400);and the at least one radar-transparent section (400) with the radar coupling surface (402) for coupling in the radar radiation and with a coupling-out surface (404) for coupling out the coupled radar radiation and for emitting a light distribution which represents the at least one ornament (4), depending on light introduced into an inner light-guiding section (406) of the radar-transparent section (400) by means of the outer light-guiding section (200) along an imaginary circumferential path (220);

Description

Prior ArtRadomes or covers for automotive radar systems installed in the radiator grille are arranged behind a manufacturer's emblem in the vehicle center of the radiator grille in the prior art.Disclosure of the InventionThe problems of the prior art are solved by a lighting device according to claim 1.An aspect of the description relates to the following subject matter: An illumination device, in particular for a motor vehicle, for the visible representation of at least one ornament, the illumination device comprising: a plurality of light sources for generating light; at least one outer light guide section, which is arranged with respect to an optical axis of the illumination device outside a radar coupling surface of at least one radar-transparent section for coupling radar beams, wherein the at least one outer light guide section guides the light generated by the light sources and coupled in via a respective coupling surface from a respective light coupling surface into the at least one radar-transparent section; and the at least one radar-transparent section having the radar coupling surface for coupling in the radar radiation and having a coupling-out surface for coupling out the coupled-in radar radiation and for emitting a light distribution which represents the at least one ornament, as a function of light introduced by means of the outer light guide section along an imaginary circumferential path into an inner light guide section of the radar-transparent section; wherein at least one air gap is arranged in the light path between the coupling-in surface of the outer light guide section and the coupling-out surface of the radar-transparent section, and wherein the air gap is bounded by at least one light coupling-out surface of the at least one outer light guide section and by a light coupling-in surface of the inner light guide section.The air gap couples the inner radar transparent section and the outer light guiding section structurally, but maintains their functional cohesion in order to present the ornament in the desired shape.Moreover, adhesive measures or other connection techniques between the outer light guide section and the radar-transparent section can be dispensed with, which has a positive effect on the mullibility and the service life of the lighting device. Particularly when the two components mentioned above are bonded together, bubbles can remain in the adhesive and air gaps can remain between the components, which interfere with the passage of light from the coupling unit into the light guide on the front panel and thus prevent the reliable, uniform illumination of the brand logo or ornament.An advantageous example is characterized in that at least one fastening means fixes the at least one radar-transparent section and the at least one outer light guide section relative to one another.Advantageously, the fastening means keeps the distance between the at least one light decoupling surface and the at least one light coupling surface constant during operation of the lighting device.An advantageous example is distinguished in that an outer light guide surface, facing away from the optical axis, of the at least one outer light guide section and an inner light guide surface, facing the optical axis, run parallel to one another in a section of the outer light guide section adjoining the light decoupling surface.By selecting the parallel light guide surfaces, the demolding capability of the outer light guide section and thus the mullibility of the lighting device are improved.An advantageous example is distinguished in that a distance between an outer light guide surface of the at least one outer light guide section facing away from the optical axis and an inner light guide surface facing the optical axis increases in the direction of the light decoupling surface in a section of the outer light guide section adjoining the light decoupling surface.This results, for example, in a shape that is tropute in section. The increased distance has a collimating effect on the light guided in the light guide, which has a positive effect on the light distribution decoupled via the light decoupling surface of the outer light guide section.An advantageous example is characterized in that the light decoupling surface is convexly curved.The light decoupling surface is thus configured in the form of a converging lens in order to emit the light to be decoupled as a light bundle with a lower divergence. Due to the smaller divergence of the beam bundle, the loss of efficiency due to a distance D from the light coupling surface 820 is less severe than in the case of a planar adhesive surface without an air gap.An advantageous example is distinguished in that light is decoupled from the light decoupling surface with a main light emission direction, wherein the light coupling surface follows an imaginary vertical plane of the main light emission direction at least in sections.An advantageous example is distinguished in that the main light emission direction associated with the light decoupling surface encloses an angle with the optical axis of 25° to 65°, in particular 35° to 55°, in particular 40° to 50°.The beams should be coupled as flat as possible into the front grill element in order to achieve the highest possible light guiding efficiency there. In order to increase the coupling efficiency in the case of the flat incidence selected by the angle of the main light emission direction with the optical axis, it is proposed to increase the light entry surface by means of the selected light coupling surface on the front grill element or on the radar-transparent section.An advantageous example is distinguished in that the light decoupling surface delimiting the at least one light gap and the light coupling surface delimiting the at least one light gap define a respective imaginary plane which intersect along an imaginary line which is arranged on the one hand between the light coupling surface and the optical axis and is arranged on the other hand facing away from the decoupling surface of the radar-transparent section.This steep positioning of the light coupling surface achieves efficient coupling, as a result of which the light beams from the light guide collar are refracted into the front grill element or the radar-transparent section.An advantageous example is characterized in that the illumination device comprises a radar component which is set up to receive and / or transmit radar waves through the radar-transparent section.In the drawing, the following are shown: FIG. 1 shows a lighting device for a motor vehicle in a schematic section; and FIGS. 2 to 6 each show the lighting device in the region of an air gap.FIG. 1 shows a lighting device 2, in particular for a motor vehicle, in a schematic illustration in a section. The illumination device 2 comprises a plurality of light sources for emitting light and a light guide section 200 which, with respect to an optical axis A of the illumination device 2, is arranged, for example, radially outside a radar coupling surface 402 of a radar-transparent section 400 for coupling radar beams 6 and extends at least in sections along an imaginary circumferential section 220 which is arranged at the transition of the section 400 into an inner light guide section 406. The imaginary circumferential section 220 can be designed, for example, in the form of a circle, polygon or as any desired line guide. In this case, the circumferential section 220 can be closed in itself or can be partially open. In the example, the circumferential section 220 is substantially circular and is formed closed in itself. It can be provided that the circumferential section 220 is adapted to a predefined installation space for the lighting device 2. As a result, the light guide section 200 can also be adapted or adapted to the installation space.The light sources 100 are configured as a respective LED in the example. It can be provided that a plurality of LEDs are arranged on one or more printed circuit boards 108 and form the light sources 100. Furthermore, it can be provided that an LED band provides the light sources. LEDs with one or more selected colors can be used or RGB LEDs, wherein the individual light sources of the RGB LEDs can generate the colors directly or at least a part of the colors will generate color converters / fluorescent dyes pumped with blue or UV light.It can be provided that the printed circuit board 108 is configured to be contiguous or divided. In this case, the LEDs arranged on the contiguous and / or divided printed circuit board 108 can be provided in groups of different numbers and with different or uniform distances between the LEDs or the groups.In the example shown, the light sources 100 are arranged in a plane 110. It can be provided that the LEDs are arranged in different planes.In another example, the light sources are arranged on four individual printed circuit boards which lie in the plane 110 and which are rotated clockwise by 45° or 90° adjacent to one another (axis of rotation is the optical axis in the direction of the travel direction). In this case, in each case two printed circuit boards on opposite sides are jointly actuated by a respective control function of the at least one control unit 500. Alternatively, the mutually opposite printed circuit boards or printed circuit boards are operated by a respectively assigned control device. As a result, the proportion of the luminous flux guided into the radome is halved if one of the two sides fails, as a result of which homologation as position light of the later overall panel can be realized later, although the division of the light sources does not take place geometrically mirror-symmetrically.The light guide section 200 comprises at least one light coupling surface 202 for coupling in the light of the light sources 100, 100 a, 100 b, wherein the light guide section 200 guides the coupled-in light 102 proceeding from the light coupling surface 202 to a light transition region 300 between the light guide section 200 and the radar-transparent section 400.In addition, the light guide section 200 has, toward the light transition region 300, a light guide surface 230 formed by a convex outer contour 206 facing away from an imaginary extension of the optical axis A of the illumination device 2.A curvature of the convex outer contour 206 can be adapted to the predefined installation space for the lighting device 2. In addition, it can be provided that the curvature of the convex outer contour 206 is differently formed at corresponding points on the imaginary circumferential section 220. In an exemplary embodiment, the light guide surface 230 is formed by a rotation of the convex outer contour 206 about the optical axis A.The convex outer contour 206 can be designed in its basic shape as an ellipse which can be deformed into a free-form surface on account of given conditions or a desired guidance of the light 102.The illumination device 2 further comprises the radar-transparent inner section 400 with the radar coupling surface 402 for coupling in the radar radiation 6 and with a coupling surface 404 for coupling out the coupled-in radar radiation 6 and for emitting a light distribution 106 depending on light introduced into the inner radar-transparent section 400 by means of the light guide section 200.Radar-transparent section 400 is designed to couple incoming radar radiation into radar-transparent section 400 at radar coupling-in surface 402 and to couple it out at coupling-out surface 404. Radar transparency as a property of the radar-transparent section corresponds to an attenuation of <2 dB.In the example, the radar radiation 6 is generated and / or processed by a radar device or component 8. The radar component 8 is thus arranged with respect to the radar transparent portion 400 such that the radar component 8 receives and / or transmits radar waves through the radar transparent portion 400.The radar component 8 receives and / or transmits the radar waves with a magnetic field direction and a field direction of the electric field, wherein a preferred direction V of the at least one heating wire 10 coincides with one of the magnetic field direction of the radar waves or encloses an angle with the magnetic field direction of less than 15°, in particular less than 10°, in particular less than 5°.The radar-transparent section 400 comprises at least one, in particular a plurality of heating elements or heating wires 10.The heating wire 10 is shown in the example as a plurality of heating coils. In the example, the heating coils consist of an electrically conductive material, in particular of a metal wire, for example a copper wire and / or nickel wire.In the example, the radar-transparent section 400 and the light guide section 200 consist of at least one material transparent to visible light, such as PC, PU, PUR, PMMA or silicone. Different materials can also be provided for the respective sections.It is provided, for example, that the at least one heating wire 10 leads at least in sections through the inner light guide section 406 of the radar-transparent section 400.The heating wire 10 is thereby integrated into the radar transparent section 400 and is surrounded by material transparent to visible light. An overall height of the illumination device along the optical axis A accordingly remains in a range of approximately a multiple of λ / 2 of the radar radiation 6 and at the same time a distance 302 of the light transition region 300 is increased. In one example, the radar radiation has a frequency of 76.5 GHz, as a result of which the overall height of the lighting device 2 is 1.4 mm when polycarbonate is used as the radar-transparent section 400. In multiples of this overall height, a transmission of the radar radiation 6 decreases with increasing order of the multiple.It can be provided that a surface 12 of the heating wire 10 comprises the color white or a white tone, in particular in the form of a layer applied to the heating wire 10.The heating wire 10 without the applied layer would be visible through the radar-transparent section 400 when the light source 100, 100 a, 100 bis switched off. When the light source 100, 100 a, 100 bis switched on, a shadow of the heating wire 10 without the applied layer would be visible through the radar-transparent section. The applied layer has the effect that the heating wire 10 is less recognizable when the light source 100, 100 a, 100 bis switched off. When the light source is switched on, the applied layer causes light impinging on the surface 12 of the heating wire 10 to be scattered in a plurality of directions, wherein the shadow of the heating wire 10, in particular parts of the heating wire, is less recognizable.The light sources 100 are operated by means of at least one control unit 500.The radar transparent portion 400 comprises light transparent openings 408 a, 408 bin a transmission-inhibiting layer 408 with a reduced transmittance for light. In the example, the transmission-inhibiting layer 408 is provided as a lacquer layer. Foils or other materials or intermediate layers are also conceivable. The transmission-inhibiting layer 408 can also be opaque.By means of the light-transparent openings 408 a, 408 bin the transmission-inhibiting layer 408, it is possible to image any desired patterns or logos in the sense of the ornament 4 through which the light 102 introduced into the radar-transparent section 400 exits. This results in illumination of the ornament formed by the light-transparent openings 408 a, 408 b, which is recognizable in particular in the top view of the illumination device 2.It can be provided that a reflection section 410 of the radar-transparent section 400, which is arranged oriented in the direction of the coupling-in surface 202 for coupling in the radar radiation 6, comprises reflection surfaces 412 a, 412 bwith an increased scattering effect for incident light at least in sections. As a result, the light of the light 102 bapplied to the reflection surfaces 412 a, 412 bis scattered by the radar transparent section 400, as a result of which more light beams are directed in the direction of the optical axis A and of the light transparent openings 408 a, 408 b. Thus, more light rays pass through the apertures 408a, 408b. The region of reflection section is a reflection region for visible light-not for radar radiation.It can be provided that the reflection surfaces 412 a, 412 bhaving an increased scattering effect are arranged in such a way that the reflected and scattered light passes through the respectively assigned light-transparent opening 408 a, 408 b. In the example, the reflective surfaces 412 a, 412 bare aligned and arranged in alignment with the openings 408 a, 408 b.It can be provided that a partially transparent layer 416 with a higher transmittance than the transmission-inhibiting layer 408, which appears chromium-like in optical appearance, for example, closes the openings 408 a, 408 bat least in sections. In the example, partially transparent layer 416 is formed continuously over illumination device 2. The partially transparent layer 416 can be arranged before or after the transmission-inhibiting layer 408 in the light emission direction. Alternatively, further appearances of the partially transparent layer 416 are conceivable, such as color filters, for example. The partially transparent layer 416 can influence the appearance of the pattern imaged by the openings 408 a, 408 b, even when the light source 100 a, 100 bis switched off.It can be provided that the lighting device 2 is designed as part of a front grill for a motor vehicle, or is integrated or integratable therein.It can be provided that the at least one heating wire 10 is arranged between the associated light-transparent opening 408 a, 408 band the reflection section 410, in particular one of the reflection surfaces 412 a, 412 bwith increased scattering effect.It can be provided that the light guide region 406 is produced separately at least in sections, in particular as a heating segment. Here, the light guide portion 406 may include the heating element 10.At least one air gap 800 is arranged in the light path between the coupling-in surface 202 of the outer light guide section 200 and the coupling-out surface 404 of the radar-transparent section 400, wherein the air gap 800 is bounded by at least one light coupling-out surface 810 of the at least one outer light guide section 200 and by a light coupling-in surface 820 of the inner light guide section 406.In the section shown in FIG. 1, the convex outer contour 206 and the opposite outer contour of the outer light guide section 200 have a concentrating effect on the light bundle coupled into the outer light guide section 200 by the respective light source 100, wherein this concentrating effect is, however, different from the concentrating effect in the section perpendicular thereto (distance from the axis of rotation). The optical focusing or collimation takes place here in the meridional plane or in the sectional plane to the imaginary circumferential section 220. In the saggital plane, the light guide is slightly or not changed.At least one fastening means 900 is provided, which fixes the at least one radar-transparent section 400 and the at least one outer light guide section 200 relative to one another.For example, fastening means 900 designed as retaining tabs are located in the vicinity of the coupling-in surface 202, wherein the respective retaining tab is arranged between adjacent light sources.In one example, a screw connection takes place into the outer light guide section 200, wherein a respective one of a plurality of screws is passed through a heat sink and the printed circuit board 108 and engages in an internal thread of the outer light guide section 200. Thus, the outer light guide portion 200 is fixed to the light sources 100. The placement to the panel or radar transparent section 400 is effected by pins on the frame of the panel or radar transparent section 400, wherein the pins define the position of the radar transparent section 400 and the outer light guide section 200 with respect to one another via the retaining lugs on the outer light guide section 200.FIG. 2 shows an example of the lighting device 2 in the region of the air gap 800 in a section. An outer light guide surface 230 of the at least one outer light guide section 200 facing away from the optical axis A and an inner light guide surface 240 facing the optical axis A run parallel to one another in a section of the outer light guide section 200 adjoining the light decoupling surface 810.FIG. 3 shows an example of the lighting device 2 in the region of the air gap 800 in a section. A distance between an outer light guide surface 230 of the at least one outer light guide section 200 facing away from the optical axis A and an inner light guide surface 240 facing the optical axis A in a section of the outer light guide section 200 adjoining the light decoupling surface 810 increases in the direction of the light decoupling surface 810.In other words, the distance between the light guide surfaces 230 and 240 perpendicular to the central longitudinal course M_ 200 of the outer light guide section 200 decreases starting from the associated light decoupling surface 810.FIG. 4 shows an example of the lighting device 2 in the region of the air gap 800 in a section. The light decoupling surface 810 is convexly curved. In particular, the light decoupling surface 810 is convexly curved in an imaginary plane which coincides with the optical axis A. This results in a converging lens shape for the light decoupling surface 810.FIG. 5 shows, in a development of the example from FIG. 4, an example of the lighting device 2 in the region of the air gap 800 in a section. Light from the light decoupling surface 810 is decoupled with a main light radiation direction H. The light coupling-in surface 820 follows, at least in sections, an imaginary plane perpendicular to the main light emission direction H.The light coupling surface 820 follows a first imaginary plane which is parallel to a second imaginary plane which the associated light coupling-out surface 810 follows.Since the efficiency of the coupling in decreases greatly in the case of an air gap due to the divergence of the beam bundle, it is proposed that the collar-like outer light guide section 200 is brought up to the light coupling surface 820 in such a way that a center line M 1 of the light coupling-out surface 810 running perpendicular to the plane of the drawing corresponds to the base point for a surface normal which points to a center line M 2 of the light coupling-in surface 820 running perpendicular to the plane of the drawing.The main light emission direction H associated with the light decoupling surface 810 encloses an angle of 25° to 65°, in particular 35° to 55°, in particular 40° to 50°, with the optical axis A.FIG. 6 shows an example of the lighting device 2 in the region of the air gap 800 in a section. The light decoupling surface 810 delimiting the at least one light gap 800 and the light coupling surface 820 delimiting the at least one light gap 800 define a respective imaginary plane 812, 822 which intersect along an imaginary line 830 which is arranged on the one hand between the light coupling surface 820 and the optical axis A and is arranged on the other hand facing away from the decoupling surface 404 of the radar-transparent section 400.

Claims

An illumination device (2), in particular for a motor vehicle, for the visible representation of at least one ornament (4), the illumination device (2) comprising: a plurality of light sources (100) for generating light; at least one outer light guide section (200), which is arranged with respect to an optical axis (A) of the illumination device (2) outside a radar coupling surface (402) of at least one radar-transparent section (400) for coupling radar beams, wherein the at least one outer light guide section (200) guides the light generated by the light sources (100) and coupled in via a respective coupling surface (202) from the respective coupling surface (202) into the at least one radar-transparent section (400); and the at least one radar-transparent section (400) having the radar coupling surface (402) for coupling in the radar radiation and having a coupling surface (404) for coupling out the coupled-in radar radiation and for emitting a light distribution which represents the at least one ornament (4), depending on light introduced by means of the outer light guide section (200) along an imaginary circumferential path (220) into an inner light guide section (406) of the radar-transparent section (400); wherein at least one air gap (800) is arranged in the light path between the coupling-in surface (202) of the outer light guide section (200) and the coupling-out surface (404) of the radar-transparent section (400), and wherein the air gap (800b) is bounded by at least one light coupling-out surface (810) of the at least one outer light guide section (200) and by a light coupling-in surface (820) of the inner light guide section (406).The lighting device (2) according to claim 1, wherein at least one fastening means (900) fixes the at least one radar transparent portion (400) and the at least one outer light guiding portion (200) to each other.The lighting device (2) according to claim 1 or 2, wherein an outer light guiding surface (230) of the at least one outer light guiding portion (200) facing away from the optical axis (A) and an inner light guiding surface (240) facing the optical axis (A) extend parallel to one another in a portion of the outer light guiding portion (200) adjoining the light decoupling surface (810).The lighting device (2) according to claim 1 or 2, wherein a distance between an outer light guiding surface (230) of the at least one outer light guiding portion (200) facing away from the optical axis (A) and an inner light guiding surface (240) facing the optical axis (A) increases in a direction of the light decoupling surface (810) in a portion of the outer light guiding portion (200) adjoining the light decoupling surface (810).The lighting device (2) according to one of the preceding claims, wherein the light decoupling surface (810) is convexly curved.The lighting device (2) according to one of the preceding claims, wherein light is coupled out of the light decoupling surface (810) with a main light radiation direction (H), and wherein the light coupling surface (820) follows an imaginary perpendicular plane of the main light radiation direction (H) at least in sections.The lighting device (2) according to any one of claims 1 to 6, wherein the main light emission direction (H) associated with the light decoupling surface (810) encloses an angle with the optical axis (A) of 25° to 65°, in particular 35° to 55°, in particular 40° to 50°.The lighting device (2) according to one of claims 1 to 5 or 7, wherein the light decoupling surface (810) delimiting the at least one light gap (800) and the light coupling surface (820) delimiting the at least one light gap (800) define a respective imaginary plane (812, 822) which intersect along an imaginary line (830) which is arranged on the one hand between the light coupling surface (820) and the optical axis (A) and is arranged on the other hand facing away from the decoupling surface (404) of the radar-transparent section (400).The lighting device (2) according to one of the preceding claims, comprising a radar component (6) which is set up to receive and / or transmit radar waves through the radar-transparent section (400).

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