Abstract
The invention describes an integral lighting assembly (1A, 1B, 1C, 1D, 1E) comprising an optical arrangement (2, 3); a first light source (S.sub.1) for generating a first beam (L.sub.1) of light; a first collimator (C.sub.1) for directing the first beam (L.sub.1) at the optical arrangement (2, 3); a second light source (S.sub.2) for generating a second beam (L.sub.2) of light; and a second collimator (C.sub.2) for directing the second beam (L.sub.2) at the optical arrangement (2, 3), wherein the optical arrangement (2, 3) is realized to manipulate the first and second light beams (L.sub.1, L.sub.2) to give a first exit beam (BLO) and a second exit beam (BRI) such that the first exit beam (BLO) and the second exit beam (BRI) are partially combined in an overlap region (44) on a projection plane (4) located at a predefined distance from the integral lighting assembly (1A, 1B, 1C, 1D, 1E). The invention further describes an automotive headlamp arrangement (12) comprising such an integral lighting assembly (1A, 1B, 1C, 1D, 1E).
Claims
1. An integral lighting assembly comprising: an optical arrangement; a first light source for generating a first beam of light; a first collimator for directing the first beam at the optical arrangement; a second light source for generating a second beam of light; and a second collimator for directing the second beam at the optical arrangement; wherein the collimators are arranged such that each collimator on one side of an optical axis of the lighting assembly directs its beam of light essentially at a region of the optical arrangement on the other side of the optical axis such that at least a portion of the first beam and at least a portion of the second beam cross the optical axis at a common point on the optical axis before arriving at the optical arrangement, wherein the optical arrangement is configured to manipulate the first beam to provide a low exit beam and to manipulate the second light beam to provide a high exit beam such that the low exit beam and the high exit beam are partially combined in an overlap region on a projection plane located at a predefined distance from the integral lighting assembly and such that a majority of the high exit beam is non-overlapping with respect to the low exit beam in the projection plane, and wherein the optical arrangement comprises a first lens and comprises, on a surface of said first lens, a plurality of linear prism elements and a plurality of linear lenses that are oriented on said surface essentially perpendicular to the linear prism elements such that one of said first beam and said second beam intersects said plurality of liner prism elements and the other of said first beam and said second beam intersects said plurality of linear lenses.
2. The integral lighting assembly according to claim 1, wherein the plurality of linear lenses compose a spreading element for horizontally spreading any light incident at the spreading element and the plurality of linear prism elements compose a shifting element for vertically shifting any light incident at the shifting element.
3. The integral lighting assembly according to claim 2 wherein the spreading element is configured to spread at least part of the first beam prior to manipulation by the first lens such that the low exit beam is projected to give two overlapping first beam regions in the projection plane.
4. The integral lighting assembly according to claim 2, wherein the shifting element is configured to shift at least part of the second beam prior to manipulation by the first lens such that the high exit beam is projected to give two overlapping second beam regions in the projection plane.
5. The integral lighting assembly according to claim 2, wherein the first lens is a projection lens and wherein the shifting element is arranged to vertically shift the light incident at the shifting element prior to refraction by the projection lens.
6. The integral lighting assembly according to claim 2, wherein the first lens is a projection lens and wherein the plurality of linear lenses are a plurality of cylindrical lens elements and are arranged to refract and horizontally spread the light incident at the spreader element prior to refraction by the projection lens.
7. The integral lighting assembly according to claim 1, wherein the first lens is a projection lens.
8. The integral lighting assembly according to claim 1, wherein the first and second beams intersect at least partially in a focal plane overlap region on a focal plane of the optical arrangement so that the projection plane overlap region corresponds to the focal plane overlap region.
9. The integral lighting assembly according to claim 1, comprising a collimator arrangement in which light exit openings of the first collimator and the second collimator are located in close proximity to the focal plane of the optical arrangement.
10. The integral lighting assembly according to claim 1, comprising a collimator arrangement in which at least one of the first or second collimators comprises a prism element at its corresponding light exit opening, wherein the prism element of the collimator arrangement is configured to refract the corresponding beam of light towards the optical axis.
11. The integral lighting assembly according to claim 1, wherein at least one of the first or second light sources comprises an LED source.
12. The integral lighting assembly according to claim 1, wherein at least one of the first or second collimators comprises a near-die collimator with a length of between 6 mm and 18 mm.
13. The integral lighting assembly according to claim 1, wherein the optical arrangement is further configured to manipulate the first and second light beams such that a majority of the low exit beam is non-overlapping with respect to the high exit beam in the projection plane.
14. The integral lighting assembly according to claim 13, wherein the predefined distance is 25 meters.
15. An automotive headlamp arrangement comprising the integral lighting assembly according to claim 1.
16. An integral lighting assembly comprising an optical arrangement; a first light source for generating a first beam of light; a first collimator for directing the first beam at the optical arrangement; a second light source for generating a second beam of light; and a second collimator for directing the second beam at the optical arrangement, wherein the collimators are arranged such that each collimator on one side of an optical axis of the lighting assembly directs its beam of light essentially at a region of the optical arrangement on the other side of the optical axis such that the first beam crosses the second beam before arriving at the optical arrangement, wherein the optical arrangement is configured to manipulate the first and second light beams to give a low exit beam and a high exit beam such that the low exit beam and the high exit beam are partially combined in an overlap region on a projection plane located at a predefined distance from the integral lighting assembly, and wherein the optical arrangement comprises a first lens and comprises, on a surface of said first lens, a plurality of linear prism elements and a plurality of linear lenses that are oriented on said surface essentially perpendicular to the linear prism elements such that one of said first beam and said second beam intersects said plurality of liner prism elements and the other of said first beam and said second beam intersects said plurality of linear lenses.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 is a schematic representation of an automobile with a prior art headlamp arrangement projecting a high beam and a low beam onto a virtual projection screen;
(2) FIG. 2a is a schematic representation of a prior art lighting arrangement for projecting a high beam and a low beam onto a virtual projection screen;
(3) FIG. 2b is a schematic representation of a further prior art lighting arrangement for projecting a high beam and a low beam onto a virtual projection screen;
(4) FIG. 3 is a schematic representation of an integral lighting arrangement according to a first embodiment of the invention;
(5) FIG. 4 is a schematic representation of an integral lighting arrangement according to a second embodiment of the invention;
(6) FIG. 5 is a schematic representation of an integral lighting arrangement according to a third embodiment of the invention;
(7) FIG. 6 is a schematic representation of an integral lighting arrangement according to a fourth embodiment of the invention;
(8) FIG. 7 shows a projection lens with added functional elements for use in an integral lighting arrangement according to the invention;
(9) FIG. 8 is a schematic representation of an integral lighting arrangement according to a fifth embodiment of the invention;
(10) FIG. 9 is a schematic representation of a headlamp arrangement according to an embodiment of the invention;
(11) FIG. 10 is a schematic representation of an automobile with a headlamp arrangement of FIG. 8 for projecting a high beam and a low beam onto a virtual projection screen.
(12) In the drawings, like numbers refer to like objects throughout. Objects in the diagrams are not necessarily drawn to scale; in particular, the elements and relative positions of an optical arrangement such as a lens and a collimator are only indicated in a very simplified manner.
DETAILED DESCRIPTION OF THE EMBODIMENTS
(13) FIG. 1 is a schematic representation of an automobile 10 with a prior art headlamp 11 with a lighting arrangement projecting a low beam 160 and a high beam 170 onto a virtual projection screen 4. In the upper part of the diagram, the virtual screen 4 is shown in a side view at a standard distance D from the headlamp arrangement. According to . . . standard, the distance D must comprise 25 m, and the spatial areas 41, 42 covered by the projections of the low and high beams on the screen must satisfy certain requirements. For example, the low beam 160 must illuminate a certain minimum region 42 to the front and sides of the headlamp. The low beam 160 must be directed towards the side of the automobile away from the centre of the road, so that the verge is better illuminated, while at the same time, the low beam 160 may not be directed at an area too high on the projection plane 4. Similarly, the high beam 170 must illuminate a certain minimum region 41 above the low beam region 110, so that the road is better illuminated over a long distance. The regions 41, 42 illuminated on a virtual screen 4 are shown in a plan view in the lower part of the diagram. This plan view of the virtual screen 4 illustrates the disadvantage of prior art lighting arrangements, showing that the regions 41, 42 covered by the high beam 170 and low beam 160 respectively do not give a complete illuminated area on the virtual screen, but are separated by a gap 43. This gap 43 manifests itself, from a driver's point of view, as a dark region or badly illuminated area, and may compromise the driver's safety or the safety of pedestrians or animals on the verge or roadside.
(14) FIG. 2a is a schematic representation of a prior art lighting arrangement for projecting a high beam 170 and a low beam 160 onto a virtual projection screen 4, and makes clear how the non-illuminated area 43 can arise. Obviously, the dimensions and distances in this and the following diagrams are rendered in an overly-simplified manner and are only intended to be explanatory in purpose. Here, two light sources S.sub.1, S.sub.2 are mounted on a carrier 13 or substrate 13 located behind a lens 2 in a headlight arrangement. One light source S.sub.1 is located ‘above’ an optical axis X, and the beam of light 16 originating from this light source S.sub.1 is imaged in a first exit beam 160 or low beam 160 to give the low beam projection 42 on the virtual screen. The other light source S.sub.2 is located ‘below’ the optical axis X, and the beam of light 17 originating from this light source S.sub.2 is imaged in a second exit beam 170 or high beam 170 to give the high beam projection 41 on the virtual screen 4. In this realization, the light sources emit in a Lambertian manner, so that a large proportion of the light output is lost, as indicated by the lines 15. The image 42 made of the upper light source S.sub.1 is indicated by lines originating from the centre of the light source S.sub.1, which converge at a point on the virtual screen 4 corresponding to the centre of the light source image 42 in the first exit beam 160. Similarly, the image 41 made of the lower light source S.sub.2 is indicated by lines originating from the centre of the light source S.sub.2, which converge at a point on the virtual screen 4 corresponding to the centre of the light source image 41 in the second exit beam 170 (for the sake of clarity, only the points describing the centre of a light source and its corresponding point in the image of that light source are shown in the diagram). The gap between the light sources S.sub.1, S.sub.2 is also ‘imaged’ as the gap 43 between the regions 41, 42 on the screen. However, because two clearly distinct imaged regions are required at the projection plane distance, it is not possible to simply place the light sources S.sub.1, S.sub.2 directly beside one another.
(15) FIG. 2b is a schematic representation of a further prior art lighting arrangement for projecting a high beam 170′ and a low beam 160′ onto a virtual projection screen 4. Here, each light source S.sub.1, S.sub.2 is located in a collimator C.sub.1, C.sub.2, so that more of the light can be used to render the light source images 41, 42 on the virtual screen 4. However, the light sources S.sub.1, S.sub.2 are still separate, so that the effective gap between the light sources S.sub.1, S.sub.2 (or the light exit openings of the collimators C.sub.1, C.sub.2) also results in a corresponding gap 43 between the images regions 41, 42 on the virtual screen 4.
(16) FIG. 3 is a schematic representation of an integral lighting arrangement 1A according to a first embodiment of the invention. Here, a pair of collimators C.sub.1, C.sub.2 each enclosing a light source S.sub.1, S.sub.2 is arranged behind an optical arrangement 2, in this case a projection lens 2, so that the light exit openings of the collimators C.sub.1, C.sub.2 are situated close to and behind the focal plane FP of the lens 2. Furthermore, the collimators C.sub.1, C.sub.2 are arranged so that each collimator directs its beam of light essentially at a part of the lens 2 on the opposite side of the optical axis X as the collimator. The term ‘optical axis’ is to be understood as an imaginary line defining the path of light propagation through the lens. In the case of an essentially symmetrical lens as shown here, the optical axis may be an axis of rotational symmetry of the lens. As the diagram shows, the first collimator C.sub.1 (above the optical axis X) directs its beam of light L.sub.1 at the lower part of the lens 2 (below the optical axis X), while the second collimator C.sub.2 (below the optical axis X) directs its beam of light L.sub.2 at the upper part of the lens 2 (above the optical axis X). The ‘tight’ light cones L.sub.1, L.sub.2 emitted by the collimators C.sub.1, C.sub.2 can be obtained, for example, by using collimators C.sub.1, C.sub.2 with essentially parallel side walls. The collimators C.sub.1, C.sub.2 are arranged so that the light beams L.sub.1, L.sub.2 partially intersect (as indicated by the shaded area) to give a focal plane overlap area L.sub.FP on the focal plane FP (indicated by the thicker line). An image of the ‘object’ in the focal plane FP is projected onto the virtual screen 4 to give a high-beam region 410 corresponding to the second light beam L.sub.2, and a low-beam region 420 corresponding to the first light beam L.sub.1. An overlap area 44 on the projection screen, being the overlap between the high-beam region 410 and the low-beam region 420, is effectively the ‘image’ of the focal plane overlap area L.sub.FP on the focal plane FP of the lens 2, and is emphasized by the thick black line. This overlap area 44 ensures that, from the driver's point of view, the area illuminated by the headlamps is optimally illuminated, without any ‘dark gap’ or non-illuminated area between low beam and high beam.
(17) FIG. 4 is a schematic representation of an integral lighting arrangement 1B according to a second embodiment of the invention. This realization is a further development of the realization of FIG. 3 described above. Here, the light beams L.sub.1, L.sub.2 exiting the collimators C.sub.1, C.sub.2 are first refracted by prism elements 6 mounted at the light exit openings of the collimators C.sub.1, C.sub.2, resulting in a larger focal plane overlap area L.sub.FP on the focal plane FP. This results in a better, larger overlap region 44 on the virtual screen 4, as indicated by the thicker black line.
(18) FIG. 5 is a schematic representation of an integral lighting arrangement 1C according to a third embodiment of the invention. The principle of operation is different in this realization compared to the previous two embodiments. Here, a pair of collimators C.sub.1, C.sub.2 each enclosing a light source S.sub.1, S.sub.2 is arranged behind a projection lens 2, but the collimators are arranged so that each collimator directs its beam of light essentially at a part of the lens 2 on the same side of the optical axis X as the collimator. A first beam L.sub.1 is generated by the light source S.sub.1 in the first collimator C.sub.1, and is directed largely at the top half of the lens above the optical axis X. A second beam L.sub.2 is generated by the light source S.sub.2 in the second collimator C.sub.2, and is directed largely at the bottom half of the lens below the optical axis X. The conical light cones L.sub.1, L.sub.2 emitted by the collimators C.sub.1, C.sub.2 can be obtained, for example, by using collimators C.sub.1, C.sub.2 with an essentially parabolic shape. The collimators C.sub.1, C.sub.2 could also be realized as a bi-cavity collimator with a dividing wall, and wherein the outer walls of each collimator C.sub.1, C.sub.2 have a parabolic shape and the focal point of the parabola is located close to the common dividing wall. The projection lens 2 is equipped with additional functional elements 21, 22. A spreading element 21 is attached to the rear of the lens 2 towards the top, and a shifting element 22 is attached to the rear of the lens towards the bottom. Part of the first light beam L.sub.1 arrives at a central region of the lens 2, mostly in the upper half, and is projected onto a region 420 of the virtual screen. The rest of the first beam L.sub.1 arrives at the spreading element 21 and is spread and subsequently projected onto a region 421 on the virtual screen 4. The second beam arrives mostly in the lower half of the lens above the shifting element 22, and is projected onto a high-beam region 410 of the virtual screen 4. The remainder of the second beam arrives at the shifting element 22 where it is refracted and subsequently projected onto a shifted high-beam region 411 on the virtual screen 4.
(19) FIG. 6 is a schematic representation of an integral lighting arrangement 1D according to a fourth embodiment of the invention. This realization is a combination of the principles of operation of the previous embodiments. Again, the collimators C.sub.1, C.sub.2 are arranged so that the first and second light beams L.sub.1, L.sub.2 intersect before the focal plane FP, but the lens 2 is also augmented by shifting element 22 and a spreading element 21. Because the collimators C.sub.1, C.sub.2 are arranged to direct their light beams L.sub.1, L.sub.2 across the optical axis X, the shifting element 22 is attached to the upper region of the lens 2, and the spreading element 21 is attached to the lower region of the lens 2. Parts of the first beam L.sub.1 and second beam L.sub.2, arriving at the lens 2 between the spreading element 21 and the shifting element 22, result in a low-beam region 420 and high-beam region 410 respectively on the virtual screen 4. The focal plane overlap area L.sub.FP on the focal plane FP is projected as the overlap area 44 on the virtual screen 4, while the spreading element 21 results in a more optimal low-beam region 421, and the shifting element 22 results in an improved high-beam region 411.
(20) FIG. 7 shows a projector lens 2 with added functional elements 21, 22 for use in the embodiments of the lighting arrangement according to the invention described in FIGS. 5 and 6 above. In this realization, the shifting element 22 comprises a series of flat prism elements 220 directed to refract the incoming light away from the optical axis of the lens. This shifting element 22 is used to obtain the optimized high-beam region 411 on the virtual screen 4. The spreading element 21 comprises a series of cylindrical lenses 210 which act to spread the incoming light at this region of the lens 2, and which are used to obtain the wider low-beam region 421 on the virtual screen 4.
(21) FIG. 8 is a schematic representation of an integral lighting arrangement 1E according to a fifth embodiment of the invention. Here, instead of a projection lens, a reflector 3 is used to direct the light out of the lighting arrangement 1. The reflector 3 is only schematically indicated in a simplified manner by the curved line, which represents a part of an essentially parabolic open-ended reflector. The pair of collimators C.sub.1, C.sub.2 are both arranged above an optical axis of the reflector 3 so that images of the light sources S.sub.1, S.sub.2 can be made without any ‘shadow’ of the collimator arrangement. The actual paths travelled by the light beams in three-dimensional space can only be indicated here in the diagram. Basically, some of the light issued by the first collimator C.sub.1 is directed at a spreading element 31 of the reflector 3. Similarly, some of the light issued by the second collimator C.sub.2 is directed at a shifting element 32 of the reflector. 3 These spreading and shifting elements 31, 32 can simply be appropriately shaped regions of the reflector 3, or they can be additional optical elements attached at appropriate positions on the inside wall of the reflector 3. The reflector 3 is designed to direct the light exiting the collimators C.sub.1, C.sub.2 to a low-beam region 420, a spread low-beam region 421, a high-beam region 410, and a shifted high-beam region 411 on a virtual screen 4. Again, an overlap region 44 is given by the overlap between the high-beam region 410 and the low-beam region 420.
(22) FIG. 9 is a schematic representation of a headlamp arrangement 12 according to an embodiment of the invention, and shows a optical arrangement comprising a pair of light sources S.sub.1, S.sub.2 arranged in a pair of collimators C.sub.1, C.sub.2 located behind a projection lens 2 in a housing 120. The light sources S.sub.1, S.sub.2, here LED light sources S.sub.1, S.sub.2 of a type such as Luxeon® Altilon, are mounted on a suitable heat sink 121. One or both of the collimators can be mounted on a moveable base which can be controlled to tilt the collimator towards or away from the optical axis X of the projection lens 2. A driver 122 supplies the necessary control signals for activating one or both of the light sources S.sub.1, S.sub.2, for example according to a user input (deliberately turning a high beam on), in response to a sensor (which may detect if the vehicle is passing over a crest of a hill or if the vehicle is turning into a corner), or in response to another appropriate control signal. For any situation then, the collimators C.sub.1, C.sub.2 of the lighting arrangement can be controlled so that the low beam and high beam optimally overlap in an overlap region as described above.
(23) FIG. 10 is a schematic representation of an automobile 10 with a headlamp arrangement 12 of FIG. 8 for projecting a high beam B.sub.HI and a low beam B.sub.LO onto a virtual projection screen 4 at a distance of 25 m from the headlamp arraignment 12. Using any of the embodiments described in FIGS. 3-7 to manipulate the low and high beams B.sub.LO, B.sub.HI, an optimal overlap region 44 can be obtained on the virtual screen 4, ensuring in increase in safety of the driver and other road-traffic participants.
(24) Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention. The integral lighting arrangement described herein can be used for any combination of two different types of light, for example high-beam/DRL (daytime running lights), fog/DRL, high-beam/fog, etc.
(25) For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.
