Light Unit for a Motor Vehicle Headlamp

Abstract

The invention relates to a lamp unit (100) for a motor-vehicle lighting device, comprising: a dipped-beam module (101), a main-beam module (102), an imaging optical element (103, 503) connected downstream of the dipped-beam module (101) and the main-beam module (102), having an optical axis (104, 204, 404, 504) and a focal surface (116) orientated normal to the optical axis (104, 204, 404, 504), and a diaphragm (105, 405), which has a diaphragm edge (106, 206, 306) and extends essentially up to the focal surface (116) of the imaging optical element (103, 503) for generating the horizontal cut-off line in a light image generated by the lamp unit (100), wherein the diaphragm (105, 405) has an opaque diaphragm region (107, 407) and has a transparent diaphragm region (108, 408) with a geometric structure (109, 409) made from a transparent material at the diaphragm edge (106, 206, 306) in the region of the focal surface (116), the geometric structure (109, 409) has at least one prism body (110, 210, 310, 410, 510) with a triangular cross-sectional area, which is elongated and the longitudinal extent runs substantially transversely to the optical axis (104, 204, 404), the at least one prism body (110, 210, 310, 410, 510) has a first, a second and a third prism surface, the second prism surface (112, 212, 312, 512) encloses an internal angle α1≥θ with the first prism surface (111, 211, 311), and the third prism surface (113, 213, 313, 513) encloses an internal angle α2≥θ with the first prism surface (111, 211, 311), wherein θ is the critical angle of total internal reflection of the transparent material, the internal angles α1 and α2 are the same or different, and with the proviso that the internal angle α1 or the internal angle α2 is not 45°.

Claims

1. A lamp unit (100) for a lighting device of a motor vehicle, particularly for a motor-vehicle headlamp, comprising: at least one dipped-beam module (101) for generating a dipped-beam light distribution, for the most part below a horizontal cut-off line imaged substantially in front of the motor vehicle, at least one main-beam module (102) for generating a main-beam light distribution, for the most part above the cut-off line, an imaging optical element (103, 503) connected downstream of the dipped-beam module (101) and the main-beam module (102) in the optical beam direction for generating a total light distribution of the light modules, having an optical axis (104, 204, 404, 504) and a focal surface (116) orientated substantially normal to the optical axis (104, 204, 404, 504), and a diaphragm (105, 405), which has a diaphragm edge (106, 206, 306, 506) and extends essentially up to the focal surface (116) of the imaging optical element (103, 503) for generating the horizontal cut-off line in a light image generated by the lamp unit (100), wherein the diaphragm (105, 405) has a substantially flat opaque diaphragm region (107, 407) and has a transparent diaphragm region (108, 408) with a geometric structure (109, 409) made from a transparent material at the diaphragm edge (106, 206, 306, 506) in the region of the focal surface (116), wherein the geometric structure (109, 409) comprises at least one prism body (110, 210, 310, 410, 510) with a substantially triangular cross-sectional area, the at least one prism body (110, 210, 310, 410, 510) is elongated and the longitudinal extent runs substantially transversely to the optical axis (104, 204, 404, 504), the at least one prism body (110, 210, 310, 410, 510) has a first, a second and a third prism surface, wherein the first prism surface (111, 211, 311, 511) is substantially flush with the flat opaque diaphragm region (107, 407), the second prism surface (112, 212, 312, 512) faces the opaque diaphragm region (107, 407) and encloses an internal angle α1≥θ with the first prism surface (111, 211, 311), and the third prism surface (113, 213, 313, 513) faces away from the opaque diaphragm region (107, 407) and encloses an internal angle α2≥θ with the first prism surface (111, 211, 311), wherein θ is the critical angle of total internal reflection of the transparent material, the internal angles α1 and α2 are the same or different, and with the proviso that the internal angle α1 or the internal angle α2 is not 45°.

2. The lamp unit according to claim 1, wherein the geometric structure (109, 409) comprises at least two prism bodies (110, 310, 410) arranged one behind the other in the optical beam direction, the first prism surfaces (111, 311) of which adjoin one another longitudinally and are flush with one another.

3. The lamp unit according to claim 2, wherein the geometric structure (109, 409) comprises at least two prism bodies (110, 410) arranged one behind the other in the optical beam direction, the first prism surfaces (111) of which adjoin one another longitudinally and are flush with one another.

4. The lamp unit according to claim 1, wherein the at least one prism body (410) has two regions (410a, 410b) transitioning into one another in the longitudinal direction, which regions are offset with respect to one another in terms of height, and are connected to one another by means of a transition region (410c) through which the optical axis (404) runs.

5. The lamp unit according to claim 1, wherein the diaphragm is manufactured in one piece from the transparent material and the opaque diaphragm region is metal vapour coated or mirror coated.

6. The lamp unit according to claim 1, wherein the opaque diaphragm region is manufactured from an opaque material and the transparent diaphragm region comprising the geometric structure is an insert made from the transparent material, or the diaphragm is produced by means of a multi-component injection moulding method using transparent and opaque plastic materials.

7. The lamp unit according to claim 1, wherein the transparent material is plastic or glass.

8. The lamp unit according to claim 1, wherein the second and/or third prism surface (112, 113, 212, 213, 312, 313) is substantially planar.

9. The lamp unit according to claim 1, wherein the second and/or third prism surface (512, 513) is curved.

10. The lamp unit according to claim 1, wherein the at least one dipped-beam module (101) and the at least one main-beam module (102) comprise at least one light source in each case, wherein a collimator is assigned to each light source in the optical beam direction and the collimator is configured to reduce the size of the beam angle of the light beams generated by the light source.

11. The lamp unit according to claim 1, wherein the diaphragm (101) has at least one light window (115), wherein at least one light path runs from the dipped-beam and/or main-beam modules (101, 102) through the at least one light window (115) and through the imaging optical element (103) to the outside.

12. The lamp unit according to claim 11, wherein the at least one light path runs through the at least one light window (115) exclusively from the dipped-beam module (101) through the at least one light window (115) and through the imaging optical element (103) to the outside.

13. The lamp unit according to claim 11, wherein the at least one light window (115) is configured to be arranged in the opaque diaphragm region (107) of the diaphragm (105) and delimited by the same, wherein the light window (115) is constructed as a recess in the opaque diaphragm region of the diaphragm or consists of a transparent material.

14. A motor-vehicle headlamp having at least one lamp unit (100) according to claim 1.

15. A motor-vehicle comprising at least one lamp unit (100) according to claim 1.

16. The lamp unit according to claim 4, wherein the transition region is oblique.

17. The lamp unit according to claim 9, wherein the third prism surface (513) is curved inwardly.

Description

[0041] It is understood that the embodiments described here are merely used for illustration and are not to be considered as limiting for the invention; but rather all configurations, which the person skilled in the art may find on the basis of the description, fall within the protective scope of the invention, wherein the protective scope is determined by the claims.

[0042] In the figures, for the purposes of simpler explanation and illustration, the same reference numbers are used for the same or comparable elements. The reference numbers used in the claims should further merely facilitate the readability of the claims and the understanding of the invention and in no way have a character impairing the protective scope of the invention.

[0043] FIG. 1 shows a schematic illustration of a design variant of a lamp unit 100 according to the invention in a perspective view. FIG. 2 shows the lamp unit 100 from FIG. 1 in a side view. The lamp unit 100 is provided for installation in a lighting device of a motor vehicle, particularly for a motor-vehicle headlamp (front headlamp). The lamp unit 100 comprises a dipped-beam module 101, a main-beam module 102 and an imaging optical element, in the form of a projection lens 103 with an optical axis 104 and a focal surface 116 orientated substantially normal to the optical axis 104, also termed a Petzval surface, which imaging optical element is connected downstream of the dipped-beam module 101 and the main-beam module 102 in the optical beam direction for generating a total light distribution of the light module. The dipped-beam module 101 is set up for generating a dipped-beam light distribution, for the most part below a horizontal cut-off line imaged substantially in front of the motor vehicle. The main-beam module 102 is set up for generating a main-beam light distribution, for the most part above the cut-off line. Furthermore, the lamp unit 100 comprises an essentially horizontally lying diaphragm 105, which has a diaphragm edge 106 and extends essentially up to the focal surface 116 of the downstream-connected projection lens 103 for generating the horizontal cut-off line in a light image generated by the lamp unit 100. In this case, the diaphragm edge 106 reaches as far as the focal surface 116 or up to the focal point F of the projection lens 103.

[0044] In the example shown, the dipped-beam module 101 and the main-beam module 102 together form a collimator module, which is structured according to generally known principles and does not have to be explained in more detail at this point (see also description of collimators, e.g. TIR collimator lenses, above). The dipped-beam module 101 and the main-beam module 102 in each case comprise a plurality of light sources, which are not illustrated in more detail, e.g. realized as LEDs, wherein a collimator, which is likewise not illustrated in any more detail, is assigned to each light source in the optical beam direction. Each collimator is set up to reduce the divergence of the light beams generated by the light source. The collimator module also comprises further optical components, such as e.g. lenses or reflectors. The dipped-beam module 101 and the main-beam module 102 can however also be structured according to other design principles and are not limited to the collimator structure illustrated schematically in FIG. 1 and FIG. 2. Alternatively, the dipped-beam module and/or the main-beam module may have reflectors according to the classic PES (poly ellipsoid system) headlamp type, which is sufficiently known in the specialist field.

[0045] The features according to the invention of the lamp unit 100 are found in the diaphragm 105, which is explained in more detail in the following figures.

[0046] FIG. 3 shows the diaphragm 105 of the lamp unit 100 illustrated in FIGS. 1 and 2 in a perspective view, FIG. 4 shows a plan view onto the diaphragm 105 and FIG. 5 shows a section through diaphragm 105. FIG. 6 shows the geometric prism structure of the diaphragm of the lamp unit illustrated in FIGS. 1 and 2 in detail. The diaphragm 105 has a substantially flat opaque diaphragm region 107 and has a transparent diaphragm region 108 with a geometric structure 109 made from a transparent material at the diaphragm edge 106 in the region of the focal surface 116. It is understood implicitly that the opaque diaphragm region 107 may have a reflective surface at least to some extent.

[0047] In the example shown, the opaque diaphragm region 107 is manufactured from metal and the transparent diaphragm region 108 comprising the geometric structure 109 is an insert made from the transparent material. It is however also possible to manufacture the diaphragm 105 in one piece from the transparent material and the opaque diaphragm region 107 is vapour coated according to the known manner, e.g. vapour coated using a metal such as aluminium, wherein the transparent diaphragm region 108 is left out and is therefore not vapour coated. In the example shown, the transparent material is plastic. Instead of plastic, glass may also be chosen as opaque material.

[0048] The geometric structure 109 of the exemplary diaphragm 105 comprises two prism bodies 110 with a substantially triangular cross-sectional area in each case. Each prism body 110 is elongated and the longitudinal extent runs substantially transversely to the optical axis 104. Each prism body has a first, a second and a third prism surface, wherein the first prism surface 111 is substantially flush with the flat opaque diaphragm region 107, the second prism surface 112 faces the opaque diaphragm region 107 and encloses an internal angle α1≥θ with the first prism surface 111, and the third prism surface 113 faces away from the opaque diaphragm region 107 and encloses an internal angle α2≥θ with the first prism surface 111, wherein θ is the critical angle of total internal reflection of the transparent material, the internal angles α1 and α2 are the same or different, and with the proviso that the internal angle α1 or the internal angle α2 is not 45°.

[0049] FIG. 7 illustrates the beam path of the light beams, which are emitted by the dipped-beam module or by the main-beam module, through one of the two prism bodies 110 of the diaphragm 105 used according to the invention. The light beams 114 generated by the dipped-beam module 101 pass through the second prism surface 112 into the prism body 110 and are totally internally reflected at the first prism surface 111 and exit through the third prism surface 113, so that the generation of disruptive scattered light in the region above the H-H line is prevented. The light beams 117 which are generated by the main-beam module 102 enter through the first prism surface 111, are transmitted by the prism body and diffracted slightly upon exit through the third prism surface 113, so that the gap between the dipped beam and the main beam in the light image of the main beam function (i.e. dipped beam and main beam are switched on) is closed.

[0050] A development of the invention is likewise represented in the diaphragm 105. The diaphragm 105 has a light window 115, which is arranged in the opaque diaphragm region 107 of the diaphragm 105 and is delimited by the same. The light window 115 is created in that a window-shaped recess in the opaque diaphragm region 107 is closed using an insert plate made from transparent plastic. The light path from the dipped-beam and/or main-beam modules can run through the light window 115 and through the projection lens to the outside. By means of this development, it is possible additionally to mix the light beams, which are generated by the dipped-beam module and the main-beam module, in a targeted manner and additionally to minimize inhomogeneities in the light image of a main beam function. Furthermore, a targeted radiation of light beams is possible in regions of the light image, which are usually of particular importance for illuminating road signs (what is known as a “sign light”). For example, it may be provided that the light path runs through the light window 115 exclusively from the dipped-beam module 101 through the light window 115 and through the imaging optical element 101 to the outside. This is shown in FIG. 8, which shows a detail view of a section through the diaphragm in FIG. 1 and FIG. 2 and illustrates the beam path of the light beams 114, which are emitted by the dipped-beam module 101, through the light window 115 arranged in the diaphragm 105 (“sign light”). FIG. 8a shows an enlarged view of FIG. 8, wherein the beam path of the light beams 117, which are emitted by the main-beam module 102, is additionally illustrated. The light beams 117 from the main-beam module are totally internally reflected at the lower boundary surface 118 of the light window 115, which boundary surface is inclined to the optical axis 104 (in FIG. 8a, the totally internally reflected light beams are labelled with 117*). Thus, the light beams 117 have an angle of incidence to the normal n to the boundary surface 118 greater than the angle of total internal reflection. As a result, it is prevented that light from the main-beam module contributes to the near field in the dipped-beam light distribution and thus allows compliance with legal requirements {USA FMVSS-108 TableXVIII UB2: measuring point [4D,V] with a specification for the luminous intensity <12000 cd Maximum Photometric Intensity}. The required inclination may also be achieved by a prismatic configuration of this lower boundary surface 118.

[0051] FIG. 9 illustrates two exemplary alternative variants for triangular prisms of a diaphragm used according to the invention, namely on the one hand the arrangement of a single large triangular prism 210 with a height H and, alternatively to that, on the other hand the arrangement of a plurality of (in total five) small triangular prisms 310. The triangular prisms 210 or 310 are in each case arranged in the transparent region on the diaphragm edge of a diaphragm used according to the invention and positioned in the lamp unit according to the invention with respect to the focal surface or the focal point F of the imaging optical element (e.g. a projection lens 103 from FIG. 1 and FIG. 2). With respect to the description of the prism bodies 110 above, the triangular prisms 210 or 310 in each case comprise a first prism surface 211 or 311, a second prism surface 212 or 312, and a third prism surface 213 or 313. As can be seen well in FIG. 9, the respectively first prism surface 211 or 311 of the triangular prisms 210 or 310 runs substantially parallel to the optical axis 204. As can be seen well from FIG. 9, the second prism surfaces 312 of the five small triangular prisms 310 lie parallel to the second prism surface 212 of the large triangular prism 210; the third prism surfaces 313 of the small triangular prisms 310 lie parallel to the third prism surface 213 of the large triangular prism 210. The diaphragm edge 206 or 306 is defined by the prism edge formed from prism surfaces 211 and 213 or 311 and 313 (in the case of the small triangular prisms 310 by the outermost prism 310 located closest to the imaging optical element). In FIG. 9, the diaphragm edge 206 or 306 extends exactly up to the focal point F of the imaging optical element/projection lens.

[0052] The small triangular prisms 310 shown in FIG. 9 all have the same height H′. However, it will be evident to a person skilled in the art in the field that the heights of the prisms arranged in arranged in a row may increase steadily. This has the advantage that a smaller triangular prism triangular prism lying closer to the focal point shades proportionately fewer light beams of the main beam, which enter into the transparent geometric structure of the diaphragm through the first prism surfaces of the triangular prisms. For example, fewer light beams of the main beam are totally internally reflected at a second prism surface of a prism with a smaller height lying closer to the focal point, which enter via a first prism surface of a triangular prism with greater height. The increase of the heights of the triangular prisms advantageously follows a parabolic curve trace.

[0053] FIG. 10 shows a modified variant of a diaphragm 405 for a lamp unit according to the invention. The diaphragm 405 is substantially like the above-described diaphragm 105. The diaphragm 405 has a substantially flat opaque diaphragm region 407 and has a transparent diaphragm region 408 with a geometric structure 409 comprising two prism bodies 410 made from a transparent material at the diaphragm edge 406 in the region of the focal surface. The prism bodies 410 have two regions 410a and 410b transitioning into one another in the longitudinal direction, which regions are offset with respect to one another in terms of height, and are connected to one another by means of an oblique transition region 410c, through which the optical axis 404 runs. Likewise, the opaque region 407 also comprises two regions 407a and 407b transitioning into one another and offset with respect to one another in terms of height, which are connected to one another by means of an oblique transition region 407c, through which the optical axis 404 runs. As a result, it is possible to realize an increase in asymmetry in the light distribution. Thus, as in the case of the above-described prism bodies 110, 210 and 310, the prism bodies 410 comprise a first, a second and a third prism surface (not provided with reference numbers in FIG. 10 for reasons of space), the second prism surface faces the opaque diaphragm region 407 and encloses an internal angle α1≥θ with the first prism surface, and the third prism surface faces away from the opaque diaphragm region 407 and encloses an internal angle α2≥θ with the first prism surface, wherein θ is the critical angle of total internal reflection of the transparent material, the internal angles α1 and α2 are the same or different, and with the proviso that the internal angle α1 or the internal angle α2 is not 45°. Thus, like the diaphragm 105, the diaphragm 405 can of course also be provided with a light window 115 for creating a “sign light” function.

[0054] FIG. 11 illustrates a gradient shape for softening the cut-off line in a dipped-beam light distribution with the aid of a diaphragm used according to the invention, which has a prism body with curved prism surfaces. FIG. 12 shows an exemplary light distribution with cut-off line in a two-dimensional angular space on the basis of the lines H-H and V-V for a gradient shape according to FIG. 11. An advantage lies in the fact that the light beams totally internally reflected at the prism structure, which are radiated by the dipped-beam module, are refracted in slightly different directions, so that a softer transition or a legally compliant gradient value of the cut-off line is generated, wherein the cut-off line is primarily determined by the diaphragm edge 506. A vehicle driver then perceives the light distribution without an irritating boundary line between illuminated and dark road surface. Thus, no further measures, e.g. a microstructure on the imaging optical element, have to be put in place, in order to effect a desired softening of the cut-off line. An advantageous development of the invention is illustrated in FIG. 11. In this development, a third prism surface 513 of a prism body 510 is curved inwards, wherein the cross-sectional area is uniform in the longitudinal extent. The prism body 510 is, as described above, a component of a diaphragm used according to the invention, which is not illustrated in more detail here, however. The use of a curved third prism surface 513 (and/or a curved second prism surface 512) has the advantage, that the gradient of the cut-off line is therefore set up in a particularly targeted manner and can be positively influenced, so that the cut-off line is split and imaged in a wider manner. For an observer or the vehicle driver, a particularly soft transition of the cut-off line therefore results in the light image. The light path of light beams 516 emitted by the dipped-beam module from the curved third prism surface 513 up to the passage through a projection lens 503 is illustrated in FIG. 11 on the basis of arrows. An exemplary parallel bundle of beams 516 undergoes a divergent total internal reflection bundle of beams 516′ owing to different surface normals on the curved third prism surface 513. The divergence δ is enlarged further by the projection lens 503 owing to the different refraction of the light distribution bundle of beams 516″. Similar is also true for light beams which enter into the prism body 510 via a generally curved second prism surface 512 and after total internal reflection at the generally planar first prism surface 511, leave the prism body 510 via the curved third prism surface 513. Light is refracted at the two prism surfaces 512 and 513 according to Snell's law of refraction. It can be seen from FIG. 12 that the cut-off line HDG, which runs somewhat below and parallel to the H-H line is widened further, as a result of which the gradient decreases.

[0055] The invention may be modified in any desired manner known to the person skilled in the art and is not limited to the embodiments shown. Also, individual aspects of the invention may be picked up and substantially combined with one another. What are important are the ideas upon which the invention is based, which may be realized by a person skilled in the art, upon considering this teaching, in myriad ways and be maintained as such in spite of that.