Motor vehicle headlight with a light module featuring a micro projector

Abstract

A motor vehicle headlight includes a light module, having a light source, a primary optics that collects light and micro projectors, of which each one comprises one respective input lens, one respective output lens and an aperture that is arranged between the input lens and the output lens. The input lens, the aperture and the output lens feature one width and one height. The primary optics, the input lens, the aperture and the output lens of one respective micro projector are arranged in such a way, that the light from the light source that emits from the primary optics illuminates the input lens, and the light of the light source that emits from the input lens illuminates the output lens. The headlight includes micro projectors, whose widths (b) are different and whose heights (h) are different.

Claims

1. A motor vehicle headlight featuring at least one light module, wherein each of said at least one light module includes one light source, one primary optics that focuses the light from said one light source as well as a plurality of micro projectors, wherein each of said plurality of micro projectors comprises one respective input lens, an output lens and an aperture that is arranged between the input lens and the output lens, wherein the input lens, the aperture and the output lens define a width (b) that extends parallel to a horizontal direction and a height (h) that extends parallel to a vertical direction, wherein the primary optics, the input lens, the aperture and the output lens of one respective micro projector are arranged in such a way, that the light from the light source that emits from the primary optics illuminates the input lens, and the light from the light source that emits from the input lens illuminates the output lens, and wherein the motor vehicle headlight comprises micro projectors of said plurality of micro projectors, whose widths (b) are different from the width (b) of at least one other of said plurality of micro projectors and whose heights (h) are different from the height (h) of at least one other of said plurality of micro projectors.

2. The motor vehicle headlight as set forth in claim 1, wherein focal points of the input lens of at least one of the micro projectors are located within one expansion direction of the light of the light source that is issuing from the input lens behind the aperture of the at least one micro projector.

3. The motor vehicle headlight as set forth in claim 1, wherein each of said output lens includes a light output surface that defines a curvature, and said light output surfaces of the output lenses of at least two of the micro projectors feature the same curvature.

4. The motor vehicle headlight as set forth in claim 1, wherein the motor vehicle headlight comprises first micro projectors that feature a first width and a first height, second micro projectors that feature a second width and a second height, and third micro projectors that feature a third width and a third height.

5. The motor vehicle headlight as set forth in claim 4, wherein it comprises several light modules.

6. The motor vehicle headlight as set forth in claim 5, wherein a first light module of the several light modules only comprises first micro projectors, whose widths are equal and whose heights are equal, and that a second light module of the several light modules only comprises second micro projectors, whose widths are equal and whose heights are equal, wherein the widths of the first micro projectors are different from the widths of the second micro projectors and wherein the heights of the first micro projectors are different from the heights of the second micro projectors.

7. The motor vehicle headlight as set forth in claim 1, wherein at least one of said plurality of micro projectors, has a width that is different from the width (b) of at least one other of said plurality of said micro projectors and a height that is different from the height (h) of at least one other of said plurality of said micro projectors.

8. The motor vehicle headlight as set forth in claim 7, wherein a sum of the widths of adjacently arranged micro projectors of one light module is less than 30 mm and that a sum of the heights of micro projectors of one light module that are arranged on top of each other is less than 30 mm.

9. The motor vehicle headlight as set forth in claim 1, wherein the micro projectors define depths and the widths of the micro projectors are less than 6 mm, the heights of the micro projectors are less than 4 mm and the depths of each respective lens of the micro projectors is less than 6 mm.

10. The motor vehicle headlight as set forth in claim 1, wherein the motor vehicle headlight comprises a plurality of light modules, wherein the light-collecting primary optics of at least two of the light modules bundle the light entering into them to different degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are depicted in the drawings and are further explained in the following description. Hereby the same reference signs in the various figures refer to respectively same elements or to elements that can at least be compared based on their function.

(2) FIG. 1 shows a superimposition of three high-beam light distributions;

(3) FIG. 2 shows herewith corresponding low-beam light distributions;

(4) FIG. 3 shows an embodiment of the motor vehicle headlight in accordance with the invention;

(5) FIGS. 4a-4d are perspective views of the micro projectors of the present invention;

(6) FIG. 5 is a horizontal section of one individual single (hot spot) micro projector;

(7) FIG. 6 is a horizontal section of one row of first micro projectors along with idealized light-beam courses;

(8) FIG. 7 depicts ISO-lines of equal intensity in a hot spot low-beam light distribution that was generated by one of the several first micro projectors.

(9) FIG. 8 is a horizontal section of one individual second (wide spread) micro projector;

(10) FIG. 9 is a horizontal section of one row of second micro projectors along with idealized light-beam courses;

(11) FIG. 10 shows ISO-lines of equal intensity in a wide spread low-beam light distribution that was generated by one of the several second micro projectors;

(12) FIG. 11 is a horizontal section of one individual third (extra wide spread) micro projector;

(13) FIG. 12 is a horizontal section of one row of third micro projectors along with idealized light-beam courses;

(14) FIG. 13 shows ISO-lines of equal intensity in an extra wide spread low-beam light distribution that was generated by one of the several third micro projectors;

(15) FIGS. 14a-14d show different light modules and an ensemble of these light modules; and

(16) FIGS. 15a and 15b show a hybrid light module which comprises micro projectors, whose widths are different and whose heights are different.

DETAILED DESCRIPTION OF THE INVENTION

(17) FIG. 1 shows purely qualitatively in detail a superimposition of three high-beam light distributions 10, 12, 14, as they appear on a perpendicular screen in front of a headlight, along with the indication of a vertical direction V and the indication of a horizontal direction H. The widest one of the three light distributions will also be referred to in the following as extra wide spread light distribution 10. The next less wide high-beam light distribution will also be referred to in the following as wide spread high-beam light distribution 12, and the narrowest one of the three light distributions will also be referred to in the following as hot spot light distribution 14.

(18) FIG. 2 shows the corresponding low-beam light distribution 16, 18, 20 with a cut-off line 22 that is congruent in the overlapping area for all three low-beam light distributions 16, 18, 20. The widest one of the three light distributions will also be referred to in the following as extra wide spread low-beam light distribution 16. The next less wide light distribution will also be referred to in the following as wide spread low-beam light distribution 18, and the narrowest one of the three light distributions will also be referred to in the following as hot spot low-beam light distribution 20.

(19) FIG. 3 depicts an embodiment of the motor vehicle headlight 24 according to the invention, in a sideway section. When the headlight 24 is used in a motor vehicle according to the intended purpose, the section plane is spanned from the direction 26 of a longitudinal axis and from the direction 28 of a vertical axis of the motor vehicle. The direction 30 of a transversal axis of the motor vehicle runs perpendicular to this section plane. Headlight 24 features one light module 30, which comprises one light source 32, one primary optics 36 that bundles and parallelizes the light 34 from light source 32 as well as a plurality of micro projectors 38. Light source 32 is a semiconductor light source, preferably a light diode or laser diode, or an array comprising several of such diodes. The light module is arranged in a housing 24.1 of headlight 24. A light aperture of the headlight is covered by a transparent cover screen 24.2.

(20) Micro projectors 38 vary partially in their height in parallel direction with regards to the vertical axis 28 in FIG. 1. The first micro projectors feature a small height h1. These micro projectors are used to generate a hot spot light distribution. The second micro projectors feature a medium height h2. These micro projectors are used to generate a wide spread light distribution. The third micro projectors feature a large height h3. These micro projectors are used to generate an extra wide spread light distribution. The terms small, medium and large are hereby used for the qualitative distinction of the three differently sized micro projectors and should therefore not be understood as limitations to certain quantitative values.

(21) Each micro projector 38 comprises one input lens 40, one aperture 42 (applies to low-beam micro projectors) and one output lens 44. The end faces of the input and output coupling surfaces have the same distances from the aperture area, for the hot spot as well as the wide spread and also the extra wide spread micro projectors. As a result, the magnifying factors of these micro projectors are also the same. Thus, the micro projectors produce unevenly large images in the far field. A brightness distribution in the far field results from the superimposition of differently large images. If the distances would not be equal, but would rather be different, this would require a scaling of the apertures. Larger distances increase the focal length and reduce the aperture angle of the output light cone.

(22) In the motor vehicle headlight of the present invention, differently sized light beam cross-sections, which are projected into the far field, are produced by different sizes of the input pupils of the micro projectors. The apertures 42 are only used to shape the cut-off line. Narrow light distributions in the far field are produced by narrow input pupils (e.g. hot spot). High intensities are produced by a superimposition of several narrow light distributions, i.e. by an overlapping of the contributions of comparatively many micro projectors. Wide light distributions in the far field are produced by wide input pupils (e.g. wide spread, extra wide spread). Lower intensities are produced by an overlapping of the contributions of few micro projectors.

(23) FIGS. 4a-4d show the respective micro projectors in a perspective depiction in the same scale and in an imagined superimposition for a comparison of the sizes. FIG. 4a hereby depicts a first micro projector 46, FIG. 4b a second micro projector 48, FIG. 4c a third micro projector 50, and FIG. 4d depicts the imagined superimposition of the three micro projectors 46, 48, 50. Each one of the FIGS. 4a to 4d also depicts an optical axis 52. When the headlight is used in according to the intended purpose, the optical axis 52 runs in the direction of the longitudinal axis of the motor vehicle.

(24) Each one of the micro projectors comprises an input lens 46.1, 48.1, 50.1, an output lens 46.2, 48.2, 50.2 and an aperture 46.3, 48.3, 50.3 that is arranged between the input lens of the output lens. When the motor vehicle headlight 10 is used in according to the intended purpose, the input lenses and the apertures feature a respective width b that is extending parallel towards a horizontal direction and a height h that is extending parallel towards the vertical direction.

(25) The same applies for the output lenses. Each output lens of a micro projector preferably features the same width b and the same height h as the corresponding input lens of the micro projector. The primary optics and the input lens, the aperture and the output lens of one respective micro projector are arranged in such a way, that the light from the light source that emits from the primary optics illuminates the input lens, and the light that emits from the input lens illuminates the output lens. The micro projectors are characterized in that their widths are different and that their heights are different.

(26) FIG. 5 depicts a horizontal section of one individual first (hot spot) micro projector 46 and FIG. 6 depicts a horizontal section of one row of first micro projectors 46 along with idealized light-beam courses. FIG. 7 depicts ISO-lines of equal intensity in a hot spot low-beam light distribution that was generated by one of the several first micro projectors. These are characterized by a sharp upward cut-off line and a gentle fading out towards the sides with a gradual decrease of the brightness. Examples of light intensities are provided on the right abscissa in candela (cd).

(27) Due to their small dimensions, the local shifts in the superimposition for an overall light distribution curves on the roadway are found in the same scale as the individual micro projectors. Thus, these are found within a millimeter range and are significantly smaller than the local cross-sectional expansion of their light cones on the roadway. Such a small local shift exerts almost no influence on the sharpness of the cut-off line and may at best only contribute to an improved color mixing, or homogenization of the overall light distribution curve.

(28) FIG. 8 depicts a horizontal section of one individual second (wide spread) micro projector 48 and FIG. 9 depicts a horizontal section of one row of second micro projectors along with idealized light-beam courses.

(29) FIG. 10 depicts ISO-lines of equal intensity in a wide spread low-beam light distribution that was generated by one of several second micro projectors. These are characterized by a sharp upward cut-off line and a gentle fading out towards the sides with a gradual decrease of the brightness. Examples of light intensities are provided on the right abscissa in candela (cd).

(30) The larger cross-section profile (input pupil) is responsible for the coverage of a larger output coupling angle. The amount of wide spread micro projectors is smaller when compared to the amount of hot spot micro projectors within a comparable construction space. Therefore, although the aperture projections are identical in the course of the cut-off line on the roadway, yet overall, they are wider and thus paler (lower light intensity) in their horizontal and vertical expansion. When compared, the light distribution that was generated by the wide spread micro projectors thus features a quantitatively weaker maximum at the same location, at which also the maximum of the hot spot light distribution is located. Towards the sides, there is a gentle fading out.

(31) FIG. 11 depicts a horizontal section of one individual third (extra wide spread) micro projector 50 and FIG. 12 depicts a horizontal section of one row of third micro projectors 50 along with idealized light-beam courses.

(32) FIG. 13 depicts ISO-lines of equal intensity in an extra wide spread low-beam light distribution that was generated by one of the several third micro projectors. These are characterized by a sharp upward cut-off line and a gentle fading out towards the sides with a gradual decrease of the brightness. Examples of light intensities are provided on the right abscissa in candela (cd). It applies in this case as well, that the cut-off line of the hot spot, wide spread and extra wide spread light distributions feature an identical course in the area of their superimposition. The respective aperture edges are projected, possibly also magnified differently, as same-sized images, even if differently wide light distributions and cut-off lines are generated by differently narrow beam paths. With the same focal length of the imaging micro lenses, the aperture edges are also formed (scaled) in the same scale, i.e. all micro projectors have identical imaging ratios.

(33) In one embodiment, the optical components of the micro projectors feature the following widths B, heights H and depths T and further dimensions: Hot spot lenses: 2.3 mm1.4 mm5.0 mm (BHT) Wide spread lenses: 3.6 mm2.1 mm5.0 mm (BHT) Extra wide spread lenses: 5.0 mm3.6 mm5.0 mm (BHT) Lens distance: 4.0 mm Aperture thickness: 0.1 mm, placed centered between input lens and output lens Focal length of the input lenses: 7.0 mm Shape of the optical surfaces and input lenses: (biconical, toric, freeform) Focal length of the output lenses: approx. 7.0 mm Shape of the optical surfaces and output lenses: (spherical, aspherical)

(34) The optical axes of the imaging micro projector lenses (spherical, aspherical) determine the optical axes of the respective micro projectors and are arranged parallel or almost parallel towards each other. The narrower the individual micro projectors are, the smaller the aperture angles of the individual micro beams are, despite short focal lengths. This particularly applies to the hot spot micro projectors. In this way, less color dispersion occurs at the lens edges.

(35) As it can be derived from FIGS. 5, 8, 11, the focal points of the input lenses of the micro projectors are located downstream of the luminous flux of the aperture of the respective micro projector.

(36) The light output surfaces of the output lenses of the micro projectors are preferably curved to the same degree.

(37) FIG. 14a depicts a first light module 54, which only comprises first micro projectors. FIG. 14b depicts a second light module 56, which only comprises second micro projectors and FIG. 14c depicts a third light module 58, which only comprises third micro projectors.

(38) The first light module 54 only comprises first micro projectors, whose first widths are equal and whose first heights are equal. The second light module 56 only comprises second micro projectors, whose second widths are equal and whose second heights are equal. The third light module 58 only comprises third micro projectors, whose third widths are equal and whose third heights are equal. The heights are respectively parallel towards the vertical axis 28. The widths are respectively parallel towards the transverse axis 30.

(39) The first widths of the first micro projectors differ from the second widths of the second micro projectors and from the third widths of the third micro projectors. The first heights of the first micro projectors differ from the second heights of the second micro projectors and from the third heights of the third micro projectors.

(40) In this way, e.g., three module types are created: hot spot, wide spread and extra wide spread. Each module is made up of a collimating primary optics, an array of input lenses, an array of apertures and an array of output lenses.

(41) Each module type features the dimensions of e.g. 25 mm25 mm30 mm (height Hwidth Bdepth T). It is characterizing that the micro projector cross-sections for hot spot, wide spread and extra wide spread are different in size. The higher light intensity in the hot spot is generated by micro projectors, whose cross-section is smaller than the cross-section of the wide spread micro projectors. The cross-sections of the wide spread micro projectors are smaller than the cross-sections of the extra wide spread micro projectors. The imaging quality is best near the common optical axis 52 up to approximately +/10 towards the sides. Starting from +/10, the imaging quality naturally decreases, due to the simple construction of the projectors.

(42) Due to the good imaging quality, a proper adjusting of the individual modules towards each other results in homogeneous, seamless superimpositions of the light distributions, so that the overall light distribution, which is a result of the superimposition, can be perceived as an overall homogeneous and color-compensated light distribution. No abrupt brightness differences occur between the individual partial light distributions.

(43) FIG. 14d depicts an ensemble 60 of such a first light module 54, of such a second light module 56 and of such a third light module 58. The three light modules are preferably used together in one headlight, in order to e.g. generate a low-beam light distribution that is made up of a hot spot portion, a wide spread portion and an extra wide spread portion.

(44) In a preferred embodiment, the motor vehicle headlight is characterized in that it comprises micro projectors, whose widths are different and whose heights are different.

(45) A superimposition of several partial light distributions, which are generated by micro projectors with varying cross-sections, can also be implemented with one single light module type.

(46) FIGS. 15a and 15b depict a light module 62 that comprises micro projectors, whose widths are different and whose heights are different. FIG. 15a hereby shows a depiction, which is pulled apart along the optical axis 52, in which light source 32, primary optics 36, the array of input lenses 64, the array of apertures 66 and the array of output lenses 68 can clearly be detected as they are separated from each other. FIG. 15b depicts light module 62 in an operational assembled state. FIG. 15b shows very clearly that micro projectors 46, 48, 50 of varying cross-sections are provided.

(47) FIGS. 15a and 15b depict examples of how the different types of micro projectors 46, 48, 50, which are distributed in rows or columns or according to another pattern, can be combined into a hybrid micro projector array, wherein the term hybrid in this application describes the use of micro projectors with varying cross-sections in connection with one common collimating primary optics 36 and light source 32. By using hybrid light modules 62, it is possible to compile various combinations of hot spot, wide spread and extra wide spread micro projectors. It is thus possible to highlight the varying portions of the overall light distribution to different degrees, so that e.g. an overall light distribution with a distinct maximum or with a larger or smaller horizontal and/or vertical aperture angle are produced. Different row or column combinations, even mixed rows are possible. The micro projectors can be arranged in any desired way towards each other (preferably parallel or almost parallel), so that the complete cross-section of the light beam of the light source, which is collimated by the primary optics, can be used.

(48) By use of the values for the heights and widths of the individual micro projectors, which can be separately stipulated during their construction, it is possible to control the portions of the thereof resulting partial light distribution in their superimposition of the individual partial light distributions, so that a desired course of the light intensity in horizontal and in vertical direction can be achieved in the superimposition.

(49) In a preferred embodiment, several of such hybrid light modules are used in one headlight, wherein each hybrid light module generates a complete, scaled light distribution (scaled: differently sized, but with the same proportions). It is thus possible to generate the required light distribution comprising e.g. two to three equal hybrid light modules by use of a suitable power supply of the light sources.

(50) For the hybrid light modules 62, micro projectors of differently sized cross-sections are combined in one single micro projector module 62, so that one light source 32 or one collimator 36 can be assigned to a hot spot, a wide spread as well as an extra wide spread micro projector array. The overall light distribution of such a module 62 thus covers the entire required angle range. The overall light distribution is being defined by the mixture ratio of the micro projector cross-section types and can be finely or continuously dimmed via the power supply of the light source. Its contrast ratios are hereby ideally maintained.

(51) In practice, the collimating primary optics 36 features a residual divergence. The light of the light source, which emits from the primary optics, is thus not fully parallel, but features an opening angle of a few degrees. The cross-section of the collimated or focused luminous flux features varying local light intensities. This has the effect that, depending on where the micro projector is located within the collimating light bundle, it projects the same geometric cut-off line image onto the roadway, but illuminates it differently. Each projection possibly features a different light focus or may even be only partially illuminated. In accordance with the superposition principle, the overall light distribution is a result of the sum of the individual images. It is the objective that by the superimposition of the individual images, dispersion-related color effects cancel themselves out in their entirety.

(52) During production, the proposed hybrid light module can lead to a simplification and to higher unit numbers. Only one module type would be necessary, instead of having to develop different modules for hot spot, wide spread and extra wide spread partial light distributions and having to manufacture these in smaller numbers.

(53) The dimensions of the active optics of a hybrid light module range e.g. at 25 mm25 mm (heightwidth) and at a construction depth of approx. 30 mm. If it is supposed that three modules would be required to generate a low-beam light distribution, this would result in e.g. 25 mm75 mm30 mm (heightwidthdepth). Compared with the dimensions of a conventional projection module of approx. 75 mm75 mm120 mm (heightwidthdepth), this results in a volume reduction in the magnitude of a factor 1/12.

(54) The potential of this technology is herein by far not exhausted. It is possible to scale such hybrid light modules in a dual linear manner, which corresponds to a further volume scaling factor of . In this way, volume scalings of 1/(128)= 1/96 with reference to a conventional projector system would be possible. Of course, other factors like heat, cooling, LED light flow, control electronics and manufacturability will also affect the scaling or counteract it. Still, the present invention opens new possibilities for a miniaturization, for light technological innovation and quality improvement, for the implementation of modern design ideas for new courses in the perception as well as for the cost reduction and value enhancement of future headlight generations.

(55) The invention opens the way for an impressive reduction of construction space (reduction of up to 1/100 are possible) and generates an extremely homogeneous overall light distribution with a distinct cut-off line. The modularity and excellent manufacturability and robust operation lead to the advantage of expecting low production costs.

(56) The invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.