Abstract
The invention describes a lighting assembly for use in a lighting arrangement of a vehicle. The lighting assembly includes a projection lens and a light source array, wherein a center of the light source array and an optical axis of the projection lens have a lateral offset, and light sources of the light source array are individually controllable to adjust a swivel angle of a light beam generated by that lighting assembly. The invention further describes a controller for controlling the light sources of such a lighting assembly. The invention also describes a lighting arrangement for a vehicle, comprising such a lighting assembly and such a controller for controlling the light sources of the lighting assembly to adjust the swivel angle of the light beam. The invention also describes a method of generating a front beam for a vehicle comprising such a lighting assembly.
Claims
1. A lighting assembly for use in a lighting arrangement of a vehicle, comprising a projection lens and a light source array, wherein: a center of the light source array and an optical axis of the projection lens have a lateral offset; and light sources of the light source array are individually controllable to adjust a swivel angle of a light beam generated by that lighting assembly.
2. The lighting assembly of claim 1, wherein the optical axis of the projection lens is arranged parallel to a longitudinal axis of the vehicle.
3. The lighting assembly of claim 1, wherein the lighting assembly generates a front left beam and the center of the light source array is offset to the right of the optical axis of the projection lens.
4. The lighting assembly according to claim 1, wherein the light source array is arranged essentially perpendicularly to the optical axis of the projection lens.
5. The lighting assembly according to claim 1, wherein a light source of the light source array comprises an LED.
6. A controller for controlling light sources of the light source array in the lighting assembly according to claim 1 to adjust the swivel angle of a light beam generated by that lighting assembly, the controller comprising a control signal generation unit for generating a control signal for selectively activating specific light sources of the lighting source array on the basis of the lateral offset between the center of the light source array and the optical axis of the projection lens.
7. A lighting arrangement for a vehicle, comprising a lighting assembly for generating a light beam, and a controller according to claim 6 for controlling the light sources of the light source array to adjust the swivel angle of the light beam.
8. A method of generating a front beam for a vehicle comprising a lighting assembly for generating the beam, wherein (1) a center of a light source array and an optical axis of a projection lens have a lateral offset and (2) the projection lens is positioned to receive and project light from each of the light sources in the array, the method comprising: sensing an angle of turning of the vehicle; and generating a control signal for the lighting assembly on the basis of the lateral offset and on the basis of the angle of turning to selectively activate specific light sources of the light source array to adjust a swivel angle of the beam.
9. The method of claim 8, wherein the optical axis of the projection lens is arranged parallel to a longitudinal axis of the vehicle.
10. The method of claim 8, wherein the lighting assembly generates a front left beam and the center of the light source array is offset to the right of the optical axis of the projection lens.
11. The method of claim 8, wherein the light source array is arranged essentially perpendicularly to the optical axis of the projection lens.
12. The method of claim 8, wherein a light source of the light source array comprises an LED.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1 shows a simplified plan view of a vehicle with a prior art lighting arrangement;
(2) FIG. 2 shows a prior art lighting arrangement of a vehicle;
(3) FIG. 3 shows a lighting arrangement according to a first embodiment of the invention;
(4) FIG. 4 shows a lighting arrangement according to a second embodiment of the invention;
(5) FIG. 5 shows a lighting arrangement according to a further embodiment of the invention;
(6) FIG. 6 shows a schematic view of a lighting assembly according to an embodiment of the invention.
(7) In the drawings, like numbers refer to like objects throughout. Objects in the diagrams are not necessarily drawn to scale. In particular, the refraction of light beams through projection lenses is only schematically indicated in the diagrams.
DETAILED DESCRIPTION OF THE EMBODIMENTS
(8) FIG. 1 shows a simplified plan view of a vehicle 1 with a prior art lighting arrangement comprising left and right headlamps 40, each with an AFL front lighting assembly 40, for generating a front beam B.sub.L, B.sub.R, which front beam B.sub.L, B.sub.R comprises a left beam B.sub.L and a right beam B.sub.R. Each AFL front lighting assembly 40 comprises a projection lens 42 in front of a point light source 43, such as a xenon or halogen lamp 43. In the top of the diagram, the vehicle 1 is shown driving straight ahead, so that the front beam B.sub.L, B.sub.R is directed essentially parallel to a longitudinal axis L of the vehicle 1. The complete headlamp 40, comprising the projection lens 42 and the light source 43, can be mechanically swiveled to control the direction of projection of the front beam B.sub.L, B.sub.R. In the bottom part of the diagram, the vehicle 1 is turning to the left, and the front beam B.sub.L, B.sub.R is also directed or swiveled to the left. As the diagram shows, the lighting assemblies 40 are swiveled in order to direct the beams B.sub.L, B.sub.R in the desired direction. The amount of beam swivel is largely determined by the turning angle of the vehicle. However, for extreme turning angles, the outside beam (in this example the right-hand beam B.sub.R) is to some extent cut off, as indicated by the broken line, since the body of the vehicle 1 presents an obstruction to the beam as the projection lens 42 is directed ‘into’ the body of the vehicle.
(9) FIG. 2 shows a prior art lighting arrangement of a vehicle for generating a front beam B.sub.L, B.sub.R, comprising two lighting assemblies 50 on either side of a longitudinal axis L of the vehicle, and the lighting assemblies 50 are arranged so that the optical axis X in each case is arranged parallel to the longitudinal axis L of the vehicle. For the sake of clarity, the vehicle in which the lighting arrangement is incorporated is not shown. The lighting assembly 50 on the left-hand side of the longitudinal axis L is used to generate the left beam B.sub.L, and the lighting assembly 50 on the right-hand side of the longitudinal axis L is used to generate the right beam B.sub.R. This type of lighting arrangement does not require that the lighting assemblies 50 be movable. The light sources S.sub.51, . . . , S.sub.58 of each lighting assembly 50 can be arranged in an array 52 or matrix essentially centered about an optical axis 54 of the projection lens 51. To generate a beam that is directed essentially outwards in the direction of travel, as shown in the upper part of the diagram, only those light sources S.sub.53, S.sub.54 close to the optical axis X need to be activated, while the remainder can be turned off. To cause the beam to swivel, as shown in the lower part of the diagram, other light sources S.sub.57, S.sub.58 further away from the optical axis X are activated, while the remainder are switched off. The symmetrical arrangement of the light sources about the optical axis X of the lighting assembly 50 means that the same light sources on each side can be activated to obtain the desired beam swivel. The maximum beam swivel angle σ is indicated in the lower half of the diagram. However, for extreme angles, this type of lighting arrangement has the same disadvantage mentioned in FIG. 1 above, namely that for the outside beam, the body of the vehicle represents an obstruction so that some of the light is effectively blocked. Furthermore, this solution also suffers from poor beam definition since the light sources that are furthest away from the optical axis X—in this case light sources S.sub.51, S.sub.58 generate light which is subject to significant aberration as it passes through the projection lens 51. Therefore, when turning into a corner, the highly swiveled beam may be may not be sharp enough to comply with the front beam regulation. A more complex projection lens is required to compensate for the poor beam quality, thus adding to the overall expense.
(10) FIG. 3 shows a left lighting assembly 10 and a right lighting assembly 20 of a lighting arrangement according to a first embodiment of the invention. Here, a light source array 12 of the first lighting assembly 10 is arranged with a lateral offset d.sub.1 from the optical axis X.sub.1 of the first lighting assembly 10. Therefore, the light sources S.sub.11, . . . , S.sub.16 of the light source array 12 are arranged asymmetrically about the optical axis X.sub.1 of the first lighting assembly 10. Similarly, a light source array 22 of the second lighting assembly 20 is arranged with a lateral offset d.sub.2 from the optical axis X.sub.2 of the second lighting assembly 10, so that the light sources S.sub.21, . . . , S.sub.26 of the light source array 22 are arranged asymmetrically about the optical axis X.sub.2 of the second lighting assembly 20. In each case, the optical axis X.sub.1, X.sub.2 is arranged parallel to the longitudinal axis L of the vehicle. In this realization, each lighting assembly 10, 20 can generate a beam with a high degree of swivel, while only including those light sources that are actually required for a beam a. Light sources that would not contribute to a highly swiveled beam are simply left out, so that this design requires less light sources that the prior art solution described in FIG. 2.
(11) FIG. 4 shows a left lighting assembly 10′ and a right lighting assembly 20′ of a lighting arrangement according to a first embodiment of the invention. The first lighting assembly 10 is used for generating a left beam B.sub.L and the second lighting assembly 20′ is used for generating a right beam B.sub.R. Each lighting assembly 10′, 20′ comprises an array 12, 22 of light sources S.sub.11, . . . , S.sub.16, S.sub.21, . . . , S.sub.26 arranged symmetrically about an optical axis X.sub.1, X.sub.2 of the lighting assembly 10′, 20′. The optical axis X.sub.1, X.sub.2 of each lighting assembly 10′, 20′, in turn, is arranged at an angle Φ.sub.1, Φ.sub.2 to the longitudinal axis L of the vehicle 1. The left lighting assembly 10′ has an optical axis X.sub.1 arranged at a first angle Di to the longitudinal axis L of the vehicle 1, and the optical axis X.sub.2 of the second lighting assembly 20′ is arranged at a second angle Φ.sub.2 to the longitudinal axis L of the vehicle 1. In other words, the left-hand lighting assembly 10′ points somewhat to the left of the direction of travel of the vehicle, while the right-hand lighting assembly 20′ points somewhat to the right of the direction of travel of the vehicle. The top part of the diagram shows a front beam being generated. To this end, one or both of the light sources close to the optical axis X.sub.1, X.sub.2 are active, while the remaining light sources are turned off. Since the lighting assemblies 10′, 20′ are tilted with respect to the longitudinal axis of the vehicle, the left beam B.sub.L can be generated by activating one two of the light sources S.sub.12, S.sub.13 just to the left of the optical axis X.sub.1 of the left-hand lighting assembly 10′, while the right beam B.sub.R can be generated by activating one two of the light sources S.sub.24, S.sub.25 just to the right of the optical axis X.sub.2 of the right-hand lighting assembly 20′.
(12) When turning the vehicle into a corner, the front beam B.sub.L, B.sub.R is swiveled, whereby the degree of beam swivel is controlled by the choice of light sources that are activated. This can be done as shown in the bottom half of the diagram, where an extreme left-swiveled front beam is shown. To generate a swiveled beam into a left turn, groups of light sources of the left-hand lighting assembly 10′ and groups of light sources of the right-hand lighting assembly 20′ are successively turned on while the remaining light sources are turned off. An exemplary sequence of activated light source groups may be S.sub.12, S.sub.13; S.sub.13, S.sub.14; S.sub.14, S.sub.15; S.sub.15, S.sub.16 for the left-hand lighting assembly 10 and S.sub.23, S.sub.22; S.sub.22, S.sub.21 for the right-hand lighting assembly 20. When taking a turn to the right, the sequences would run in the opposite direction, in this case light sources S.sub.12, S.sub.13; S.sub.12, S.sub.11 for the left-hand lighting assembly 10 and light sources S.sub.22, S.sub.23; S.sub.23, S.sub.24; S.sub.24, S.sub.25; S.sub.25, S.sub.26 for the right-hand lighting assembly 20 would be activated while the other light sources are turned off. The degree of beam swivel σ.sub.1, σ.sub.2 obtainable by the lighting assembly 10′, 20′ according to the invention is less that that shown by the prior art solutions described above. However, by arranging each lighting assembly 10′, 20′ so that its optical axis is at an angle to the longitudinal axis L of the vehicle 1, the front beam can still be satisfactorily directed into the turn, while requiring less light sources that the prior art solution. Furthermore, the beam quality of the swiveled front beam obtained in this manner is satisfactorily high without requiring any complex lens design.
(13) FIG. 5 shows a lighting arrangement 2 according to the invention, with a controller 3 for controlling the light sources S.sub.11, . . . , S.sub.16, S.sub.21, . . . , S.sub.26 of the lighting arrangement 2. As already described in FIG. 4 above, the lighting arrangement 2 comprises left-hand lighting assembly 10′ and a right-hand lighting assembly 20′, in each case with an optical axis X.sub.1, X.sub.2 arranged at an angle Φ.sub.1, Φ.sub.2 to the longitudinal axis L of the vehicle. The degree of beam swivel is controlled according to the direction of travel of the vehicle. This can be determined by an appropriate sensor or signal, for example a signal obtained from the steering column of the vehicle. In this example, a signal 51 from the steering column is analyzed by an analysis unit 30 to determine an angle of turning θ. This is used by a control signal generation unit 31 which generates a control signal 13 for the left hand lighting assembly 10′ and a control signal 23 for the right-hand lighting assembly 20′. Each control signal 13, 23 comprises a number of signals 131, . . . 136, 231, . . . , 236 for individually controlling the light sources S.sub.11, . . . , S.sub.16, S.sub.21, . . . , S.sub.26 of each lighting assembly 10′, 20′. The choice of light source to be turned on or off for each light source array can also depend on the fixed angle Φ.sub.1, Φ.sub.2 of the optical axis X.sub.1, X.sub.2 of the lighting assembly 10′, 20′ to the longitudinal axis L of the vehicle. This information may, for example, be stored in the signal generation unit 31. The speed with which the front beam B.sub.L, B.sub.R is swiveled (i.e. the speed with which successive groups of light sources of a light source array are activated) may be directly related to the rate at which the vehicle is being directed into the turn. This can be determined by the analysis unit 30, for example, which may be equipped to analyze the signal 51 to determine a rate of turning of the vehicle. Using the information provided to the control unit 3, light sources S.sub.11, . . . , S.sub.16, S.sub.21, . . . , S.sub.26 of each lighting assembly 10′, 20′ can be individually turned on or turned off to control the degree of beam swivel of the front beam B.sub.L, B.sub.R.
(14) FIG. 6 shows a schematic view of a lighting assembly 10 according to an embodiment of the invention. Here, an array 12 of six naked-die LEDs S.sub.11, . . . , S.sub.16 on a substrate 60 is arranged asymmetrically, with a lateral offset d.sub.1, about the optical axis X.sub.1 of an aspheric projection lens 11. The light emitted by each LED S.sub.11, . . . , S.sub.16 is optimally directed at the projection lens 11 by a collimator 61. Each collimator 61 can have an essentially square or rectangular light exit opening, so that the collimators 61 can be placed in close proximity to each other in a one-dimensional or two-dimensional array 12. The light emitted by neighboring light sources will then appear to originate from a single light source when imaged by the projection lens 11.
(15) 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.
(16) 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. A “unit” or “module” can comprise a number of units or modules.
