DE102011108404A1 - Lighting device for vehicle i.e. car, has optical element, where light beams enter into optical element to finally emerge in exit direction opposite to incident direction with former surface and light exit takes place in solid angle - Google Patents

Abstract

The device (1) has an optical element with surfaces formed of a solid body made of plastic material. A light source is uncoupled with one of the surfaces for providing a light function for a vehicle (2). A reflector is arranged such that light beams strike on the surface in incident direction when the surface is broken. The beams enter into the element after reflected from the reflector to finally emerge in exit direction opposite to the incident direction with the surface. Light exit takes place in a solid angle and in direction, which is parallel to the incident direction. The light source is designed as an LED. The optical element is designed as a plano convex lens.

Description

The present invention relates to a lighting device for a vehicle. The lighting device comprises an optical element which is formed from a solid body and which has a first and a second surface. Furthermore, the lighting device comprises at least one light source whose light emission is at least partially coupled into the optical element via the second surface of the optical element and is coupled out at the first surface for providing a light function of the vehicle.

In the redesign of vehicles there is the problem that due to the desired aerodynamics and the desired design, the space requirements for lighting equipment, especially for the taillights, headlamps and reflectors are very tight. However, the signal effect of a luminaire is determined by the circumferential size of the radiating surface and by the luminance. Furthermore, the lighting equipment of the vehicle contributes significantly to the design of the vehicle. Due to the design of the lighting devices, the vehicle is often to be given a characteristic appearance, which is easily recognized. Furthermore, there is the problem that the cost of producing the lights should be as low as possible.

From the DE 39 21 798 A1 For example, a headlamp for a vehicle is known which has a light source which is surrounded by a reflector. From the reflector, the light rays reach a lens through which the light rays emerge from the roadway. However, the lens or the exiting main beam fills only a part of the headlight front surface. At least one residual area has a reflector, which reflects incident light from the front onto the headlight front surface in the direction of incidence.

From the DE 10 2009 009 725 A1 a lighting unit for a passenger car is known, which has a housing and a light source arranged therein and a cover which covers the front opening of the housing. Between the light source and the cover a cover member is arranged, which covers the light source and which is provided at least on one side with a partially permeable coating. The coating is in particular a partially transparent mirror layer.

Finally, out of the DE 1 351 461 a retroreflector known, which is pressed, poured or sprayed from a crystal clear translucent plastic compound. On the back of a paint coating or a metallic Verspiegelungsbelag is attached.

The present invention has for its object to provide a lighting device of the type mentioned, which can provide at least two different optical functions with low space requirement.

According to the invention this object is achieved by a lighting device with the features of claim 1. Advantageous embodiments and further developments emerge from the dependent claims.

The lighting device according to the invention is characterized in that in the lighting device, a retroreflector is integrated. The lighting device according to the invention thus provides two optical functions. On the one hand, a light function of the vehicle is provided by the light source. On the other hand, the reflector function is provided by the lighting device.

The retroreflector of the lighting device according to the invention comprises a reflector which is arranged so that light rays which impinge in a direction of incidence on the first surface of the optical element are refracted at the first surface and enter the optical element, then reflected by the reflector to finally at the first surface of the optical element again emerge in a direction opposite to the direction of incidence exit direction. The light emission takes place in a solid angle, which includes a direction which is parallel to the direction of incidence. The retroreflector is thus formed by the combination of an optical element formed as a solid body and a reflector within the lighting device. In this way, a lighting device can be provided, which has a small space requirement, but provides the aforementioned two optical functions for the vehicle.

For the purposes of the invention, a solid body is understood to mean that there is no interface within the body of the optical element in which a discontinuous change in the refractive index results. Such discontinuous changes in refractive index occur only at the outer surface of the optical element. The solid body of the optical element is formed, in particular, from a plastic, in particular from polycarbonate or polymethyl methacrylate (PMMA). The refractive index of the material of the solid body of the optical element is, for example, in a range of 1.4 to 1.8, in particular, the refractive index is about 1.6.

In the case of the luminous device according to the invention, the outlet direction can be aligned parallel to the direction of incidence, but opposite to the direction of incidence. However, if the retroreflector serves to reflect, for example, the light of a headlight of a following vehicle back to the driver of the following vehicle, it is necessary that the reflected light beam in the exit direction at least partially has a certain deviation from a light beam aligned parallel to the direction of incidence is so that the light is reflected to the driver of the following vehicle. For this reason, the radiation of the retroreflector takes place in the exit direction in a solid angle, this solid angle includes at least one direction which is aligned parallel to the direction of incidence. The light beam emerging in the solid angle is radiated, in particular offset parallel to the incident light beam.

The opening angle of the solid angle may be dependent on the orientation of the plane which extends in the light emission direction of the lighting device. For example, the vertical opening angle of the solid angle may be in a range of 5 ° to 20 °. The vertical opening angle is in particular 10 °. Furthermore, it is in particular arranged symmetrically about the direction which is parallel to the direction of incidence. In this case, reflection takes place through the retroreflector at a vertical angle of ± 5 ° about the direction of incidence of a light beam. This relatively small vertical opening angle is sufficient so that light emissions from vehicles of other road users are reflected back to the other road users.

The horizontal opening angle of the solid angle is preferably greater than the vertical opening angle. The horizontal opening angle may be in a range of 30 ° to 50 °. He is in particular 40 °. If it is arranged symmetrically around a direction parallel to the direction of incidence, it is reflected by ± 20 ° around the direction of incidence. This larger horizontal opening angle of the solid angle takes into account the fact that the distribution of other road users in a horizontal direction in a larger

Opening angle may occur. From this it is achieved that the vehicle, which is equipped with the lighting device according to the invention, can be particularly well perceived by other road users.

According to a development of the lighting device according to the invention, the optical element for incident light rays forms a converging lens, in the focal point of which the reflector is arranged. This embodiment advantageously achieves that a very large proportion of the incident light is reflected by the retroreflector. Furthermore, one can generate a very exact retroreflective characteristic by the converging lens and the reflector.

In the luminous device according to the invention, the reflection required for the reflection takes place on a reflector surface of a reflector and not by total reflection at interfaces with different refractive index. The reflector is designed in particular as a mirror.

According to one embodiment of the lighting device according to the invention, the reflector is arranged on the third surface of the optical element. This third surface faces away from the first surface. It is thus the back of the optical element. This third surface of the optical element can be coated in particular with a reflection surface of the reflector. In this way, the reflector can advantageously be formed with a very small space requirement directly on the optical element of the lighting device. In addition, in this embodiment, the lighting device can be produced very inexpensively. The coating can be carried out in a manner known per se. For example, the optical element may be provided with a metal layer by vapor deposition or plating or otherwise. The third surface of the optical element is provided in particular with an aluminum layer.

According to another embodiment of the lighting device according to the invention, the reflector is arranged at a distance from the third surface of the optical element, which faces away from the first surface. In this case, incident light rays exit the optical element at the third surface, are then reflected by the reflector, and then enter the optical element again at the third surface. This embodiment of the lighting device is advantageous if sufficient space for the distance between the optical element and the reflector is available and the mass or volume of the solid body of the optical element for weight or cost reasons should be low.

The reflector of the lighting device according to the invention is arranged in particular with respect to the emission direction of the lighting device behind the second surface, in which the light emission of the light source is coupled. Also, with this embodiment, the space requirement of the lighting device according to the invention can be reduced, since the light source can be arranged with respect to an axis in the emission direction of the lighting device between the first surface and the reflector.

According to a development of the lighting device according to the invention, the first surface is bent convexly at least in one direction. The first surface is bent convexly, in particular in the case of a horizontal section through the optical element. In this way, it is advantageously achieved that the horizontal opening angle for the light entrance and light exit of the retroreflector is particularly large.

According to a development of the luminous device according to the invention, the retro-reflector radiates back light rays which are incident in a first plane, in particular a vertical plane, at an angle in a range of ± 10 ° to ± 20 ° about a central axis and in a second plane, in particular a horizontal plane , at an angle in a range of ± 20 ° to ± 40 ° around a central axis. In this way, it is advantageously achieved that incident light beams are reflected back from a very large solid angle range of the retroreflector of the lighting device according to the invention.

The invention will now be explained by means of embodiments with reference to the attached drawings:

1 shows a view of an embodiment of the lighting device according to the invention in a vehicle,

2 shows a perspective view of an embodiment of the lighting device according to the invention,

3 shows a view of the first surface of the lighting device of in 2 shown embodiment,

4 shows a horizontal section through the lighting device of in 2 shown embodiment,

5 schematically shows a section through a further embodiment of the lighting device according to the invention and

6 schematically shows a section through a further embodiment of the lighting device according to the invention.

The embodiments of the lighting device according to the invention described below relate to a tail lamp of a vehicle. The rear light can provide a rear reflector and a tail light function, a brake light function, a reversing light and / or a direction indicator. In the same way, however, the lighting device may also be a headlight for a vehicle. In this case, a low beam function, a high beam function, a daytime running light function and / or a direction indicator would be provided as the light function in particular.

The arrangement of the tail light 1 in the vehicle 2 is in 1 shown. The following is related to the 2 to 4 A first embodiment of the designed as a taillight lighting device 1 explains:
The lighting device 1 includes an optical element 3 , The optical element 3 is formed as a solid body of polycarbonate or polymethyl methacrylate (PMMA). The refractive index of the material of the optical element is about 1.6. The optical element may for example have a length of 210 mm, a width of 140 mm and a height of 40 mm. However, the dimensions can be adapted to the space requirements of the vehicle.

In the direction of radiation of the lighting device 1 has the optic element 3 a first surface 4 on. The optical element 3 can do so in the vehicle 2 be built in, that the first surface 4 an outer surface of the vehicle 2 forms. However, it is also possible that in the emission direction of the lighting device 1 still a separate lens is provided.

The first surface 4 is convexly curved or curved. In 4 the curvature is shown in a horizontal plane. The first surface 4 may have a similar curvature in the vertical direction. In cross section, the optical element is rectangular, wherein the extent in the horizontal direction is substantially greater than the extension in the vertical direction, so that the curvature in the vertical direction is less visible than the curvature in the horizontal direction.

For a second surface 5 of the optical element 3 Light from one or more light sources enters the optical element 3 coupled. In the present embodiment are at the lateral edge of the optical element 3 heatsink 6 arranged, in each of which boards are arranged with a plurality of light-emitting diodes. The light emission of the LEDs is via the collimator optics 8th at the second surface 5 in the optical element 3 coupled. The light beams L1 then penetrate the optical element 3 in the edge area and occur at the first surface 4 to provide the desired lighting function.

In the lighting device 1 Furthermore, a reflector is integrated. This is the one from the first surface 4 turned away surface 9 as a reflector 10 educated. The surface 9 is vapor-deposited with a metal layer that acts as a mirror. The surface 9 is parabolic, so through the reflector 10 a parabolic mirror is provided. The surface 9 is located in the emission direction of the lighting device 1 behind the second surface 5 in which the light emission of the light source into the optical element 3 is coupled.

The optical element 3 is for incident light rays 12 designed as a convergent lens. For a light beam incident in parallel from different directions, the reflector is located 10 each at the focal point of the condenser lens. It is thus for incident light bundles from different directions a reflection surface at the reflector 10 provided, which is always in the focal point of the lens. An incident light beam 12 is thus entering the optical element 3 Broken. In the visual element 3 the light beam spreads 13 then in the direction of the reflector 10 out. At the reflector 10 it is reflected, so that a ray of light 14 back to the first surface 4 at which it is broken again and in an exit direction as a light beam 15 from the optical element in the opposite direction to the direction of incidence of the light beam 12 exit. Ideally, the outgoing light beam 15 parallel to the incoming light beam 12 , But that the incoming light beam 12 is not reflected back exactly to the original light source is the optical element 3 or the reflector 10 designed so that a scattering of the reflected back light beam occurs, so that light emerges in a solid angle Ω. This solid angle Ω includes a direction parallel to the direction of incidence of the light beam 12 is. The vertical opening angle of this solid angle is 10 °, symmetrically ± 5 ° about the direction which is parallel to the direction of incidence of the light beam 12 is. In the horizontal direction, the opening angle of the solid angle is Ω 40 ° and ± 20 ° symmetrically about the direction which is parallel to the direction of incidence of the light beam 12 is.

The curvature of the first surface 4 is designed so that the reflector of the lighting device 1 Reflects rays of light which are incident in a vertical plane at an angle of ± 15 ° about a central axis M and which are incident in a horizontal plane at an angle of ± 30 ° about the central axis M.

In reference to 5 is another embodiment of the lighting device 1 described:
The lighting device 1 of the second embodiment differs from the lighting device 1 of the first embodiment in that the reflector 11 not directly on a surface of the optical element 3 is arranged, but spaced from the optical element 3 , The optical element 3 is formed in this case as a plano-convex converging lens, at the focal point of the spaced parabolic reflector 11 is arranged. An incident light beam 16 is thus at the first surface 4 of the optical element 3 broken, penetrating as a ray of light 17 the optical element 3 and then out of the optical element 3 withdraw. As a ray of light 18 becomes the incident light at the reflector 11 reflects and reaches as a light beam 19 back to the back surface of the optical element 3 , There it enters the optical element again 3 as a ray of light 110 one to at the first surface 4 exit as light beam L11. Ideally, the rays of light 16 and L11 in parallel. However, there is some scattering in the reverberation, so that, as in the first embodiment, light exits into the solid angle Ω.

Similar to the first embodiment, also in the second embodiment, at the outer edge of the optical element 3 designed as light emitting diodes light sources 7 with a heat sink 6 be arranged as it is schematic in 5 is shown.

In reference to 6 is another embodiment of the lighting device 1 explains:
This third embodiment differs from the first embodiment in that the second surface 5 not on the edge of the optical element 3 is arranged, but centrally in the middle. There, the light emission of the light source occurs 7 in the optical element 3 one. Next to the second surface 5 is the reflector 10 at the back surface of the optical element 3 educated. The reflector 10 is located as in the first embodiment in the focal point of the optical lens designed as a converging lens 3 , The beam path of the light rays 12 to 15 for the reflector of the lighting device 1 is thus the same as in the first embodiment.

In all Ausführungsbespielen the reflection of the reflector takes place not by total reflection as in known reflectors, but on the so-called cat's eye principle. Incident light rays are focused by a convex lens and reflected by a reflector located directly in the focal point of the lens.

LIST OF REFERENCE NUMBERS

1

lighting device

2

vehicle

3

optical element

4

first surface

5

second surface

6

heatsink

7

light source

8th

collimator optics

9

third surface

10

reflector

11

reflector

V

vertical direction / level

H

horizontal direction / level

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3921798 A1 [0003]
• DE 102009009725 A1 [0004]
• DE 1351461 [0005]

Claims (10)

Lighting device ( 1 ) for a vehicle ( 2 ) with - an optical element formed from a solid body ( 3 ) having a first and a second surface ( 4 ) and - at least one light source ( 7 ), whose light emission at least partially over the second surface ( 5 ) of the optical element ( 3 ) into the optical element ( 3 ) and at the first surface ( 4 ) for providing a light function of the vehicle ( 2 ), characterized in that - in that 1 ) a reflector is integrated, which is a reflector ( 10 ; 11 ), which is arranged such that light beams (L2, L6), which in a direction of incidence on the first surface ( 4 ) of the optical element ( 3 ), at the first surface ( 4 ) and into the optical element ( 3 ), then from the reflector ( 10 ; 11 ), and finally at the first surface ( 4 ) of the optical element ( 3 ) exit again in an exit direction opposite to the direction of incidence, wherein the light exit takes place in a solid angle (Ω), which comprises a direction which is parallel to the direction of incidence. Lighting device ( 1 ) according to claim 1, characterized in that the vertical opening angle of the solid angle (Ω) is in a range of 5 ° to 20 °. Lighting device ( 1 ) according to claim 1 or 2, characterized in that the horizontal opening angle of the solid angle (Ω) is in a range of 30 ° to 50 °. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the optical element ( 3 ) forms a converging lens for incident light beams (L2, L6), at the focal point of which the reflector ( 10 ; 11 ) is arranged. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the reflector ( 10 ) on a third surface ( 9 ) of the optical element ( 3 ) arranged from the first surface ( 4 ) is turned away. Lighting device ( 1 ) according to one of claims 1 to 4, characterized in that the reflector ( 11 ) spaced from a third surface ( 9 ) of the optical element ( 3 ) arranged from the first surface ( 4 ) is turned away, so that incident light rays ( 16 ) at the third surface ( 9 ) from the optics element ( 3 ), from the reflector ( 11 ) and then again at the third surface ( 9 ) into the optical element ( 3 ) enter. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the reflector ( 10 ; 11 ) with respect to the emission direction of the lighting device ( 1 ) behind the second surface ( 5 ) is arranged. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the solid body of the optical element ( 3 ) is formed of a plastic. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the first surface ( 4 ) is convexly curved in at least one direction. Lighting device ( 1 ) according to one of the preceding claims, characterized in that the retroreflector reflects back light rays incident in a first plane at an angle in a range of ± 10 ° to ± 20 ° about a central axis (M) and in a second plane in a Angle in a range of ± 20 ° to ± 40 ° around the central axis (M).

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