DE102023122466A1 - lighting device with radar-transparent section - Google Patents

Abstract

A lighting device (2) comprising: at least one light source (100a, 100b) for emitting light; a light-guiding section (200) which, with respect to an optical axis (4) of the lighting device (2), is arranged radially outside a radar coupling surface (402) for coupling in radar beams (6) of an inner radar-transparent section (400) and extends at least in sections along an imaginary circumferential path (220), wherein the light-guiding section (200) comprises at least one light coupling surface (202) for coupling in light (102a) of the at least one light source (100, 100a, 100b), wherein the light-guiding section (200) guides the coupled-in light (102a) from the light coupling surface (202) to a light transition region (300) between the light-guiding section (200) and the radar-transparent section (400), and wherein the light-guiding section (200) to the light transition region (300) has a (2) has a light-guiding surface (206) formed by a convex outer contour (204) facing away; and the radar-transparent inner section (400) with the radar coupling surface (402) for coupling in the radar radiation (6) and with a coupling-out surface (404) for coupling out the coupled-in radar radiation (6) and for emitting a light distribution (104) depending on light (102b) introduced into the inner radar-transparent section (400) by means of the light-guiding section (200).

Description

State of the art

The invention relates to a lighting device with a radar-transparent section for a motor vehicle.

When designing a motor vehicle, the design freedom is often limited in terms of the available or specified installation space. This is particularly true when it comes to accommodating driver assistance systems such as radar equipment. If an aesthetic factor, such as the lighting of a logo, also has to be taken into account, the design freedom is further reduced.

disclosure of the invention

In order to ensure the best possible radar transparency, it is necessary to position a light source for illumination outside of a radar cone. In addition, it is not possible to provide deviations in the geometry within the radar cone, for example through microlenses or coupling contours, without significantly affecting the radar transparency.

Accordingly, radar-transparent illumination of a logo, for example in a front grille of a motor vehicle, is desirable, in which as much light from the light source as possible is directed into the center of the logo without significantly restricting the functionality of the radar device in the area of the radar cone.

This object is achieved by a lighting device according to an independent claim.

One aspect of the description relates to the following subject matter: A lighting device comprising at least one light source for emitting light; a light-guiding section which, with respect to an optical axis of the lighting device, is arranged outside, in particular radially outside, a radar coupling surface for coupling in radar beams of an inner radar-transparent section and extends at least in sections along an imaginary circumferential path, wherein the light-guiding section comprises at least one light coupling surface for coupling in light from the at least one light source, wherein the light-guiding section guides the coupled-in light from the light coupling surface to a light transition region between the light-guiding section and the radar-transparent section, and wherein the light-guiding section has a light-guiding surface formed by a convex outer contour facing away from the optical axis of the lighting device towards the light transition region; and the radar-transparent inner section with the radar coupling surface for coupling in the radar radiation and with a coupling-out surface for coupling out the coupled radar radiation and for emitting a light distribution depending on the light introduced into the inner radar-transparent section by means of the light guide section.

By arranging the light guide section outside the radar coupling surface, a lighting device is provided in which the inner radar-transparent section is illuminated without restricting the installation space for a radar device for transmitting and/or receiving the radar radiation. This enables further degrees of design freedom and a more flexible design, for example of an illuminated front grille of a motor vehicle, since the lighting device, in particular the light guide section, can be adapted to an existing installation space. In addition, the radar-transparent section can initially be optimally designed for the radar device and its function without taking into account the coupling of the light into it. The light guide section can then be adapted to the radar-transparent section and the remaining installation space. Due to the convex outer contour of the light guide section, the light coupled in by the at least one light source is guided into the radar-transparent section with a small number of reflections. In addition, the coupling of the light into the radar-transparent section can be further influenced by designing the convex outer contour, for example by choosing the focal points of this surface, thereby further increasing the flexibility of the lighting device.

An advantageous example is characterized in that the light guide section has a light guide surface towards the light transition region, which is formed by a concave inner contour facing the optical axis of the lighting device. By means of the concavely shaped inner contour, the light from the at least one light source, which is reflected on the light guide surface formed by the concave inner contour, is also guided into the radar-transparent section with a small number of reflections.

An advantageous example is characterized in that the light guide section is curved, particularly in a section encompassing the optical axis, in such a way that the light guided in the light guide section has a main light propagation direction in the light guide section which forms an angle with an imaginary vertical plane of the optical axis of the lighting device, which is greater than or equal to -15° and less than 70°, in particular greater than or equal to 0° and less than 60°, in particular greater than 3° and less than 50°, in particular greater than 5° and less than 45°. The curvature of the light guide section makes it possible to adjust the angle at which the light is guided into the radar-transparent section via the light transition area. This can influence a number of reflections in the radar-transparent area.

An advantageous example is characterized in that the light guide section and the radar-transparent section are separately manufactured components, wherein the at least one light guide section and the radar-transparent section are materially connected, in particular glued, in the light transition area. This makes it possible to produce a lighting device that could not be manufactured in one piece, for example due to undercuts. In addition, further degrees of design freedom arise when the light guide section and the radar-transparent section are manufactured separately.

An advantageous example is characterized by a joining surface that runs in steps. This makes the joining surface easy to produce and results in a large surface area, which improves bonding.

An advantageous example is characterized by the fact that a joining surface in the section encompassing the optical axis is continuously smooth, in particular straight or curved. This creates a self-centering joining surface that avoids air inclusions during bonding.

An advantageous example is characterized in that a proximal end of the convex outer contour of the light guide section and a proximal end of the inner contour of the light guide section lie in imaginary vertical planes of the optical axis that are spaced apart from one another by a distance. The distance improves the coupling of the light via the light transition area into the radar-transparent section, since the distance prevents undesirable reflections when coupling the light.

An advantageous example is characterized in that the distance is selected such that a cross-section of the light guide section that is effective for the luminous flux and is perpendicular to the main light propagation direction decreases towards the light transition region, namely by a maximum of 50%, in particular a maximum of 70%, in particular by a maximum of 80%, in particular in comparison to a largest cross-section of the light guide section.

An advantageous example is characterized in that the radar-transparent section comprises light-transparent openings in a transmission-inhibiting layer with a reduced degree of light transmission. The light-transparent openings allow the appearance of the emitted light distribution to be freely selected. For example, a logo or a brand can be displayed.

An advantageous example is characterized in that a reflection section of the radar-transparent section, which is arranged in the direction of the radar coupling surface for coupling in the radar radiation, comprises at least sections of reflection surfaces with an increased scattering effect for incident light. Due to the reflection surfaces with an increased scattering effect, the light coupled into the radar-transparent section is reflected more frequently in the direction of the radar coupling-out surface, whereby the radiated light distribution is improved in terms of its brightness and intensity.

An advantageous example is characterized by the fact that the reflection surfaces with increased scattering effect are arranged in such a way that the reflected and scattered light passes through the respective associated light-transparent opening. This orientation of the reflection surfaces with increased scattering effect improves the appearance of the emitted light distribution depicted through the light-transparent openings in terms of brightness and light intensity.

An advantageous example is characterized by the fact that a partially transparent layer, which appears to be chrome-like in appearance, for example, with a higher degree of transmission than the transmission-inhibiting layer, closes the openings at least in sections. The partially transparent layer can be used, for example, to select a color for the appearance shown through the light-transparent openings, which results in further degrees of design freedom for the lighting device.

• 1 eine schematische Darstellung eines Schnitts einer Beleuchtungseinrichtung;
• 2 eine schematische Darstellung des Schnitts einer Ausführungsform der Beleuchtungseinrichtung;
• 3 einen Teilbereich des Schnitts der Beleuchtungseinrichtung;
• 4 eine schematische Darstellung einer Draufsicht der Beleuchtungseinrichtung;
• 5 eine schematische Darstellung einzelner Teilbereiche der Beleuchtungseinrichtung im Schnitt.

Further advantageous embodiments emerge from the following description and the drawing. In the drawing:

• 1 a schematic representation of a section of a lighting device;
• 2 a schematic representation of the section of an embodiment of the lighting device;
• 3 a partial section of the lighting device;
• 4 a schematic representation of a top view of the lighting device;
• 5 a schematic representation of individual parts of the lighting device in section.

The 1 shows a schematic representation of a lighting device 2, in particular for a motor vehicle, in a section AA. The lighting device 2 comprises at least one light source 100a, 100b for emitting light, a light guide section 200, which is arranged with respect to an optical axis 4 of the lighting device 2 outside a radar coupling surface 402 for coupling in radar beams 6 of an inner radar-transparent section 400 and extends at least in sections along an imaginary circumferential section 220, which in 4 is shown. The imaginary circumferential section 220 can be designed, for example, to be circular, polygonal or as any desired line. The circumferential section 220 can be closed in itself or open in sections. In the example, the circumferential section 220 is essentially circular and closed in itself. It can be provided that the circumferential section 220 is adapted to a predetermined 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 source 100a, 100b is designed as an LED in the example. It can be provided that a plurality of LEDs are arranged on a circuit board and form the light source 100a, 100b. It can also be provided that an LED strip forms the light source 100a, 100b.

For example, the light source 100a, 100b is formed from a circuit board 102 with LEDs arranged thereon. It can be provided that the circuit board 102 is formed in a continuous or divided manner. The LEDs arranged on the continuous and/or divided circuit board 102 can be provided in groups of different numbers and with different or uniform distances between the LEDs or the groups. In one example, LEDs or groups of LEDs are supplied with different currents in order to optimize the homogeneity of the light distribution emitted by the lighting device 2.

In the example, the LEDs of the light source 100a, 100b are arranged in a plane 105. It can be provided that the LEDs are arranged in different planes.

The light guide section 200 comprises at least one light coupling surface 202 for coupling in light 102a of the at least one light source 100a, 100b, wherein the light guide section 200 guides the coupled light 102a 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 a light guide surface 206 towards the light transition region 300, which is formed by a convex outer contour 204 facing away from an imaginary extension of the optical axis 4 of the lighting device 2.

A curvature of the convex outer contour 204 can be adapted to the specified installation space for the lighting device 2. In addition, it can be provided that the curvature of the convex outer contour 204 is different at corresponding points on the imaginary circumferential section 220.

The convex outer contour 204 can be designed in its basic form as an ellipse, which can be deformed into a free-form surface due to given conditions or a desired guidance of the light 102a.

The lighting 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-out surface 404 for coupling out the coupled radar radiation 6 and for emitting a light distribution 104 depending on light 102b introduced into the inner radar-transparent section 400 by means of the light guide section 200.

The radar-transparent section 400 is also designed to couple incoming radar radiation into the radar-transparent section 400 at the coupling surface 404 and to couple it out at the radar coupling surface 402.

In the example, the radar radiation 6 is generated and processed by a radar device 8.

In the example, the light guide section 200 has a light guide surface 210 towards the light transition region 300, which is formed by a concave inner contour 208 facing the optical axis 4 of the lighting device 2.

A curvature of the convex outer contour 204 can be adapted to the specified installation space for the lighting device 2. In addition, it can be provided that the curvature of the concave inner contour 208 is different at corresponding points on the imaginary circumferential section 220.

It can be provided that the curvature of the concave inner contour 208 is different at the corresponding points to the curvature of the convex outer contour 204. It is also conceivable that the concave inner contour 208 and the convex outer contour 204 run parallel to each other.

In the example, the light guide section 200 is curved in the section A-A comprising the optical axis 4 such that the light 102a guided in the light guide section 200 has a main light propagation direction 106 in the light guide section 200, which in the light transition region 300 encloses an angle 108 with an imaginary vertical plane 110 of the optical axis 4, which is greater than or equal to -15° and less than 70°, in particular greater than or equal to 0° and less than 60°, in particular greater than 3° and less than 50°, in particular greater than 5° and less than 45°. The further the light coupling surface 202 is spaced from the optical axis 4, the flatter the angle 108 of the light 102b introduced into the radar-transparent section 400 becomes. The angle 108 influences a number of reflections of the light 102b coupled into the radar-transparent section 400 in the radar-transparent section 400; the flatter the angle 108, the lower this number of reflections becomes. As a result, the light 102b coupled into the radar-transparent section 400 loses less brightness.

In addition, a design of the convex outer surface 204 also has an influence on the angle 108. An ellipse is defined in its basic form by two focal points. In the case of an elliptical shape of the convex outer contour, in the example, depending on the precise dimensioning of the convex outer contour 204, a first focal point would result in the area of the light source 100a, 100b and a second focal point in the radar-transparent section 400. By deforming the elliptical basic shape of the convex outer contour 204 into a free-form surface, a position of the first and second focal points can be influenced. For example, if the second focal point in the radar-transparent section 400 is shifted further in the direction of the optical axis 4, a flatter angle 108 results.

The 2 shows schematically an embodiment of the lighting device 2 in the section AA, wherein the light guide section 200 and the radar-transparent section 400 are separately manufactured components, and wherein the at least one light guide section 200 and the radar-transparent section 400 are materially connected, in particular glued, in the light transition region 300.

In addition, the radar-transparent section 400 in this embodiment comprises a heating element 10 with heating coils 12. The heating element 10 ensures error-free functioning of the radar device 8, since, for example, icing of the coupling-out surface 404 can be prevented.

In the example, a joining surface 302a runs in steps. As shown in the 2 As shown, a joining surface 302b in the section AA comprising the optical axis 4 can run continuously smoothly, in particular straight or curved. Several steps or a conical course can also be provided in the joining surface 302a, 302b.

For efficient light coupling into the central area of the logo lighting, the greatest possible distance between the side of the radar-transparent section 400 facing the radome and the back of the heating element 10 is desirable. The smaller the distance, the steeper the light coupling into the logo lighting. This and the geometric expansion of the collar outwards influences the number of reflections of the light on the way from the collar to the center of the light guide, whereby the light intensity in the center in Figure A decreases particularly sharply.

Light emanating from the light source is guided from outside the radar-transparent section 400 to the radar-transparent section 400 by the surrounding light guide collar in the sense of the light guide section 200. The light guide collar/light guide section 200 has a circular shape and runs around the vehicle logo, for example. However, a "polygonal" shape of the surrounding coupling collar is also possible if this brings advantages for increasing efficiency or reducing the space required.

The light 12 is largely reflected by the semi-transparent layer 7 and is guided like in a light guide. On the underside of the heating element there is either a reflective layer or an interface with air, so that the underside acts like a light guide. The higher the reflection, the better the light-guiding effect.

The coupling out of the light in the overall system is done as follows: Light is coupled into the collar via the LEDs and guided along the outer walls of the collar in such a way that the highest possible reflection is guided into the light guide (area between 7 and 8 + 9) at the flattest possible angle. Within the light guide, the rays are reflected between the upper reflection level 7 and the lower final layer by the heating element 9, as can be seen in Figures A and B.

The 3 represents a section of the light guide section 200 of the lighting device 2. A proximal end 212 of the convex outer contour 204 of the light guide section 200 and a proximal end 214 of the inner contour 208 of the light guide section 200 lie in imaginary vertical planes 218a, 218b of the optical axis 4, which are spaced apart from one another by a distance 216. The larger the distance 216 is selected, the more light rays of the coupled light 102a are guided through the light transition region 300 into the radar-transparent section 400 without further reflections.

The distance 216 is selected such that a cross-section X, Y of the light guide section 200 that is effective for the luminous flux and is perpendicular to the main light propagation direction 106 decreases towards the light transition region 300, namely by a maximum of 50%, in particular a maximum of 70%, in particular by a maximum of 80%, in particular in comparison to a largest cross-section Y of the light guide section 200.

The 4 shows a top view of the lighting device 2 of the 2 , whereby in the following description both 2 as well as on 4 Reference is made to the radar-transparent section 400. The radar-transparent section 400 comprises light-transparent openings 406a, 406b in a transmission-inhibiting layer 406 with reduced light transmittance. In the example, the transmission-inhibiting layer 406 is provided as a lacquer layer. Films or other materials or intermediate layers are also conceivable. The transmission-inhibiting layer 406 can also be opaque.

By means of the light-transparent openings 406a, 406b in the transmission-inhibiting layer 406, any pattern or logo can be reproduced through which the light 102b introduced into the radar-transparent section 400 exits. This results in an illumination of the pattern reproduced through the light-transparent openings 406a, 406b, which is particularly recognizable in the top view of the lighting device 2.

It can be provided that a reflection section 408 of the radar-transparent section 400, which is arranged oriented in the direction of the radar coupling surface 402 for coupling in the radar radiation 6, comprises at least in sections reflection surfaces 410a, 410b with an increased scattering effect for incident light. As a result, the light 102b introduced into the radar-transparent section 400 onto the reflection surfaces 410a, 410b is scattered, whereby more light rays are directed in the direction of the optical axis 4 and the light-transparent openings 406a, 406b. More light rays thus pass through the openings 406a, 406b.

It can be provided that the reflection surfaces 410a, 410b with increased scattering effect are arranged in such a way that the reflected and scattered light passes through the respectively associated light-transparent opening 406a, 406b. In the example, the reflection surfaces 410a, 410b are aligned and arranged in alignment with the openings 406a, 406b.

The distance between the scattering surfaces or reflection surfaces 410a, 410b controls the viewing angle of the illuminated logo in such a way that more or less light can be specifically radiated into a respective viewing angle by the arrangement of the scattering surfaces 410.

Opposite the main light emission direction parallel to axis 4, 2 the scattering surfaces or reflection surfaces 410a, 410b are spaced behind the openings 406a and 406b of the transmission-inhibiting layer 406. As a result, the light intensity perceived by the viewer is increased opposite to the main radiation direction and rather reduced laterally.

In an example not shown, the scattering surfaces or reflection surfaces 410a, 410b are arranged offset from the openings 406a and 406b, so that the light intensity perceived by the observer is reduced opposite to the main radiation direction and is rather increased when looking at the lighting device from the side.

It can be provided that a partially transparent layer 412, which appears chrome-like in optical appearance, for example, with a higher degree of transmission than the transmission-inhibiting layer 406, closes the openings 406a, 406b at least in sections. In the example, the partially transparent layer 412 is formed continuously across the lighting device 2. The partially transparent layer 412 can be arranged in the optical direction before or after the transmission-inhibiting layer 406. Alternatively, other appearances of the partially transparent layer 412 are conceivable, such as color filters. The partially transparent layer 412 can influence the appearance of the pattern imaged through the openings 406a, 406b even when the light source 100a, 100b is switched off.

It can be provided that the lighting device 2 is designed as part of a front grille for a motor vehicle or is integrated or can be integrated into it.

The 5 shows the light guide section 200 as a part of the lighting device 2 in the 4 indicated sections B, C and D in a schematic representation. The sections B, C and D run through different points of the circumferential section 220 and the optical axis 4. In the example, sections B, C and D show different designs of the convex outer contour 204 and the concave inner contour 208. In the example, these differences relate to the curvature and the distance of the light coupling surface 202 from the optical axis 4.

By dimensioning the light guide section 200 at predetermined sections, in the example sections B, C and D, the light guide section 200 can be designed as desired along the circumferential section 220 and adapted to the allocated installation space. A course of the light guide section 200 between the light guide sections 200 dimensioned at the predetermined sections can be calculated or determined, for example, using various interpolation algorithms.

Claims (12)

A lighting device (2) comprising: at least one light source (100a, 100b) for emitting light; a light-guiding section (200) which, with respect to an optical axis (4) of the lighting device (2), is arranged outside a radar coupling surface (402) for coupling in radar beams (6) of an inner radar-transparent section (400) and extends at least in sections along an imaginary circumferential path (220), wherein the light-guiding section (200) comprises at least one light coupling surface (202) for coupling in light (102a) of the at least one light source (100, 100a, 100b), wherein the light-guiding section (200) guides the coupled-in light (102a) from the light coupling surface (202) to a light transition region (300) between the light-guiding section (200) and the radar-transparent section (400), and wherein the light-guiding section (200) to the light transition region (300) has a (2) has a convex outer contour (204) facing away from the light guide surface (206); and the radar-transparent inner section (400) with the radar coupling surface (402) for coupling in the radar radiation (6) and with a coupling-out surface (404) for coupling out the coupled-in radar radiation (6) and for emitting a light distribution (104) depending on the light (102b) introduced into the inner radar-transparent section (400) by means of the light guide section (200). The lighting device (2) according to claim 1 , wherein the light-guiding section (200) has a light-guiding surface (210) towards the light transition region (300) formed by a concave inner contour (208) facing the optical axis (4) of the lighting device (2). The lighting device (2) according to claim 1 or 2 , wherein the light guide section (200) is curved, in particular in a section (AA) comprising the optical axis (4), such that the light (102a) guided in the light guide section (200) has a main light propagation direction (106) in the light guide section (200) which, in the light transition region (300), encloses an angle (108) with an imaginary vertical plane (110) of the optical axis (4) of the lighting device (2), which angle is greater than or equal to -15° and less than 70°, in particular greater than or equal to 0° and less than 60°, in particular greater than 3° and less than 50°, in particular greater than 5° and less than 45°. The lighting device (2) according to one of the preceding claims, wherein the light-guiding section (200) and the radar-transparent section (400) are separately manufactured components, and wherein the at least one light-guiding section (200) and the radar-transparent section (400) are materially connected, in particular glued, in the light transition region (300). The lighting device (2) according to the claim 4 , wherein a joining surface (302a) extends in steps. The lighting device (2) according to the claim 4 , wherein a joining surface (302b) in the section (AA) comprising the optical axis (4) runs continuously smooth, in particular straight or curved. The lighting device (2) according to one of the preceding claims, wherein a proximal end (212) of the convex outer contour (204) of the light-guiding section (200) and a proximal end (214) of the inner contour (208) of the light-guiding section (200) lie in imaginary vertical planes (218a, 218b) of the optical axis (4) spaced apart from one another by a distance (216). The lighting device (2) according to one of the preceding claims, wherein the distance (216) is selected such that a cross-section (X, Y) of the light guide section (200) that is effective for the luminous flux and is perpendicular to the main light propagation direction (106) decreases towards the light transition region (300), namely by a maximum of 50%, in particular a maximum of 70%, in particular by a maximum of 80%, in particular in comparison to a largest cross-section (Y) of the light guide section (200). The lighting device (2) according to one of the preceding claims, wherein the radar-transparent portion (400) has light-transparent openings genes (406a, 406b) in a transmission-inhibiting layer (406) with reduced transmittance for light. The lighting device (2) according to the claim 9 , wherein a reflection section (408) of the radar-transparent section (400) arranged in the direction of the radar coupling surface (402) for coupling in the radar radiation (6) comprises at least sectionally reflection surfaces (410a, 410b) with increased scattering effect for incident light. The lighting device (2) according to the claim 10 , wherein the reflection surfaces (410a, 410b) with increased scattering effect are arranged such that the reflected and scattered light passes through the respectively associated light-transparent opening (406a, 406b). The lighting device (2) according to one of the Claims 9 until 11 , wherein a partially transparent layer (412), which appears, for example, chrome-like in optical appearance, with a higher transmittance than the transmission-inhibiting layer (406), closes the openings (406a, 406b) at least in sections.

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