Motor vehicle headlamp with projection light modules

Abstract

A vehicle headlight with a first projection light module is presented, comprising a first projection lens, a first auxiliary light source, and a first light guide plate. The light guide plate is arranged in a tilted position, such that the first part of the first light guide plate is located further away from the first projection lens along the first optical axis than the second part of the light guide plate. Configurations with partially colored light guide plates and white-emitting auxiliary light sources, as well as configurations with colorless light guide plates and colored auxiliary light sources, and with colorless light guide plates and white-emitting auxiliary light sources, are described.

Description

[0001] The present invention relates to a motor vehicle headlight according to the preamble of claim 1.

[0002] Such a motor vehicle headlight is already known from FR 3 079 597 A1.

[0003] Furthermore, a projection light module is known from DE 10 2018 113 768 A1 and comprises a first projection light module comprising a first semiconductor light source, a first projection lens, a first auxiliary light source, and a first light guide plate. The first projection lens has a first optical axis and a first light entry surface that can be illuminated by the first auxiliary light source through the first light guide plate. The first auxiliary light source is arranged on a narrow side of the first light guide plate such that light emanating from the first auxiliary light source enters the first light guide plate transversely to the first optical axis.The first light guide plate has a front emission side facing the first projection lens and a rear deflection side opposite the front emission side, as well as a first part located closer to the first optical axis and a second part located farther from the optical axis. The first part and the second part are components of the first light guide plate.

[0004] To implement automotive headlights with an LED low beam and an LED high beam or LED matrix high beam, these headlights are increasingly being equipped with a low beam LED module, which generates the full low beam of the headlight, and a matrix high beam module, which additionally performs the matrix function in the high beam case. A matrix function here means that the high beam distribution has a plurality of matrix elements in the form of segments of the light distribution, which can be individually dimmed to avoid glaring other road users while simultaneously achieving good illumination of the road with bright segments.

[0005] In motor vehicle headlights with a projection light module for high beam and a projection light module for low beam, it is desired that both projection lenses of the projection light modules appear luminous even when only the low beam is switched on in order to achieve a uniform appearance between the partial high beam and the low beam

[0006] For this purpose, an additional LED was previously installed on the LED board of the matrix high beam module, and its light was directed to the lens entrance side via two metallized reflectors. The arrangement of the reflectors was chosen so that the light path of the matrix function was not disrupted and the reflective surface of the second reflector was close to the image plane of the projection lens.

[0007] If the matrix elements of the high beam distribution are generated via converging lenses assigned to the respective LEDs, i.e. with a refractive attachment lens, and their imaging via the downstream common projection lens, the additional light used to brighten the projection lens runs via two metallized reflectors.

[0008] This results in a different light color than with matrix light. This cannot be completely compensated for even by selecting the appropriate LEDs, especially their corresponding color coordinates. The described optical system for lens illumination of the high beam module differs, above all, from that of the low beam module. This causes the light color of the auxiliary light to differ from that of the low beam.

[0009] Furthermore, the inevitable tilted arrangement of the second reflector of the known auxiliary light only inadequately approximates the image plane of the projection lens. This leads to an inhomogeneous appearance of the luminous lens.

[0010] According to the above-mentioned DE 10 2018 113 768 A1, a homogeneous luminance is generated at the level of the attachment optics of the matrix light module using a light guide plate. The light guide is fed with additional light from one LED at a time, located on the side of the matrix light LED board. The light propagating within the light guide plate is directed towards the projection lens by prisms attached to its back. This achieves homogeneous illumination of the light guide plate. This, and the position of the light guide in the image plane of the projection lens, already creates a homogeneous appearance of the projection lens for the viewer, corresponding to the shape of the projection lens, even if the projection lens is not fully illuminated for its actual purpose of generating a spotlight distribution.

[0011] Surprisingly, it has been shown that the tilted arrangement further improves the homogeneity of the illumination of the first projection lens with additional light. The object of the invention is to achieve an even more uniform appearance between the partial high beam and the low beam.

[0012] This object is achieved with the features of claim 1. A preferred embodiment is characterized in that the first projection light module is a high beam module. The matrix high beam has the property that the appearance of the lens changes depending on the position of the light and dark matrix elements. Therefore, the invention, which ensures a more uniform appearance, is particularly advantageous here.

[0013] It is also preferred that the motor vehicle headlight comprises a second projection light module, which comprises a second semiconductor light source, a second projection lens and a second additional light source as well as a second light guide plate, wherein the second projection lens has a second optical axis and a second light entry surface, which can be illuminated with the second additional light source through the second light guide plate, wherein the second additional light source is arranged on a narrow side of the second light guide plate in such a way thatthat light emanating from the second additional light source enters the second light guide plate transversely to the second optical axis, and the second light guide plate has a front emission side facing the second projection lens and a rear deflection side opposite the front emission side, as well as a first part located closer to the second optical axis and a second part located further away from the second optical axis, and that the light guide plate is arranged in a tilted position in which the first part of the second light guide plate is located further away from the second projection lens along the second optical axis than the second part of the second light guide plate.

[0014] It is further preferred that the second projection light module has a mirror cover running from the rear to the front in the motor vehicle headlight and that the light guide plate is arranged below the mirror cover.

[0015] This configuration provides a low-beam module with improved illumination of the projection lens. Surprisingly, it has been shown that this configuration also further improves the homogeneity of the illumination of the second projection lens with additional light. By using the same features in the low-beam module as in the high-beam module, additional homogenization and alignment of the light color of the lens illumination of the low-beam lens to the lens illumination of the high-beam lens can be achieved.

[0016] A further preferred embodiment is characterized in that the light color of the additional light source is fixed and differs from the light color of the high beam and / or the low beam. This embodiment results in a fixed illumination of the remaining colorless light guide that is deliberately different from the light color of the high beam and / or the low beam, thus resulting in a correspondingly multicolored illumination of the projection lens.

[0017] A further preferred embodiment is characterized in that the first light guide plate and / or the second light guide plate has at least one colored area.

[0018] It is also preferred that the colored area is a light entry area of ​​the otherwise colorless transparent light guide plate.

[0019] It is further preferred that the colored area is a colored coated light entry area of ​​the otherwise colorless light guide plate.

[0020] These embodiments, in which the light guide plate or parts thereof, in particular the feed area (2.1), are made of a colored-transparent material, have the effect that a desired colored illumination of the projection lens(es) can be achieved by feeding the light guide plate(s) with a white-light-emitting LED. This provides an alternative to the use of colored light sources.

[0021] This attachment lens would then be bi-colored, a so-called two-component (2K) part. Specifically, the interface between the two components, together with the entrance surface, can be optimized to ensure uniform colored illumination of the remaining light guide (2.2).

[0022] Another variant instead of a two-color light guide plate consists in a coating of the entrance surface of the otherwise colorless light guide plate, the optical properties of which are designed in such a way that it is only transparent to light of a fixed color or wavelength and absorbs or reflects all light of other colors or wavelengths.

[0023] It is also preferred that the light color of the first and / or second additional light source is controllably variable and can differ from the light color of the high beam and / or the low beam.

[0024] It is further preferred that the first and / or second additional light source has individually controllable, differently colored light-emitting diodes.

[0025] A temporally changing color of the lens illumination, especially a deliberately different color from the low beam and high beam main lighting functions, cannot be realized with the above-mentioned prior art. This limitation of the possible appearances, with which, for example, a colored welcome light can be created with the headlights, is eliminated by this design.

[0026] A further preferred embodiment is characterized in that the individually controllable, differently colored light-emitting diodes comprise a red light-emitting light-emitting diode, a green light-emitting light-emitting diode and a blue light-emitting light-emitting diode.

[0027] An alternative to the use of the light guide plate according to the invention could be one for both functions, i.e. for the function of generating a light distribution and the function of uniform illumination of the projection lenses, could be the use of an attachment optics common to these two functions.

[0028] Further advantages will become apparent from the following description, drawings and subclaims.

[0029] Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.

[0030] Showing, in schematic form: Figure 1 shows a motor vehicle headlight with details of its spatial arrangement; Figure 2 shows a vertical section through a motor vehicle headlight; Figure 3 shows a first projection light module from the front; Figure 4 shows a second projection light module; Figure 5 shows a front view of the second projection light module; and Figure 6 shows a schematic plan view of an RGB LED; Figure 7 shows a light guide plate that is made entirely or partially from a colored-transparent material. Figure 8 shows an arrangement with a tilted first light guide plate, which is characterized by a uniformly curved transition from its emission and deflection sides into the narrow sides used to feed in the additional light; Figure 9 shows an arrangement with a light guide plate that is less high in the vertical direction than the light guide plate of the Figure 8; and Figure 10 shows a further arrangement with a light guide plate which is less wide in the horizontal direction between right and left than the light guide plate of the Figure 8 .

[0031] In detail, the Figure 1 a motor vehicle headlight 10 with a main beam direction 12 pointing forward v. The designation h indicates a rear position, while the designations r and l indicate a right side and a left side, and the designations o and u indicate an upper and a lower position. The motor vehicle headlight 10 has a first projection light module 14 and a second projection light module 16. The location and position designations front, rear, right, left, top, and bottom each refer to an orientation of the motor vehicle headlight in space during its intended use in a motor vehicle.

[0032] Figure 2shows a vertical section through the motor vehicle headlight 10, running between the front v and rear h, which has a housing 18 whose light exit opening is covered by a transparent cover plate 20. The first projection light module 14 has a first semiconductor light source 22, a first projection lens 24, a first additional light source 26, and a first light guide plate 28. The first projection lens 24 has a first optical axis 30 and a first light entry surface 32. The first light entry surface 32 can be illuminated with additional light 34 from the first additional light source 26 through the first light guide plate 28.The first additional light source 26 is arranged on a narrow side 36 of the first light guide plate 28 such that additional light 34 emanating from the first additional light source 26 enters the first light guide plate 28 transversely (namely laterally, in particular in the right-left direction) to the first optical axis 30 running in the front-rear direction, and the first light guide plate 28 has a first front emission side 38 facing the first projection lens 24 and a first rear deflection side 40 opposite the first front emission side 38, as well as a first part 42 located closer to the first optical axis 30 and a second part 44 located further away from the first optical axis 30.According to the invention, the first light guide plate 28 is arranged in a tilted position in which the first part 42 of the first light guide plate 28 is located further away from the first projection lens 24 along the first optical axis 30 than the second part 44 of the first light guide plate 28. The light guide plate is not arranged at right angles to the first optical axis, in particular in the vertical section in which the first optical axis 30 also lies.

[0033] Figure 3shows the first projection light module 14 from the front. In this embodiment, two additional light sources 26 are provided, one of which is arranged on a right-hand narrow side 36.r and one on a left-hand narrow side 36.1. The additional light 34 emanating from the additional light sources 26 enters the first light guide plate 28 from the side and is distributed evenly in the first light guide plate 28, also through total internal reflection. At deflection structures arranged in the first rear deflection side 40 of the first light guide plate 28, the additional light 34 is deflected so steeply towards the first front emission side 38 of the first light guide plate 28 that it exits there in a uniformly distributed manner. By scattering structures 52 arranged in the first front emission side 38, the exited additional light 34 is scattered at least in the vertical direction such that it illuminates the first light entry surface 32 of the first projection lens 24 in a uniformly distributed manner.

[0034] The Figures 2 and 3 The first projection light module 14 shown is a high-beam module. The light emanating from the first semiconductor light source 22 is not shaded or redirected by a horizontal aperture.

[0035] The first semiconductor light source 22 of the first projection light module 14 has n LEDs arranged side by side, each of which illuminates exactly one first optical attachment section 56 of a first optical attachment 50, which is assigned only to it. The number of first optical attachment sections 56 is accordingly also equal to n. The number n here is equal to 6, without n being limited to this value. The individual LEDs and the first additional light source 26 are individually controllable by a control unit 58 of the first projection light module 14. The Figure 3The visible light exit surfaces of the first optical attachment sections 56 are projected forward by the first projection lens 24, with the images arranged in the same way as the light exit surfaces of the first optical attachment sections 56. By dimming individual LEDs, sections of the high beam distribution can be dimmed individually to avoid dazzling other road users. For this purpose, the control unit 58 processes signals from a vehicle environment sensor system, e.g., a camera and / or radar sensors.

[0036] In all embodiments of the first projection light module 14, the first (upper) part 42 of the first light guide plate 28 is located directly below the first optical attachment sections 56 and in or near the imaging plane of a first projection lens 24 or a projection lens system. This allows for homogeneous illumination of the first projection lens 24, which, as such, is visible even at small viewing angles (e.g., less than 5°) relative to the first optical axis 30 of the first projection lens 24.

[0037] Figure 4shows the motor vehicle headlight 10 with a second projection light module 16. The second projection light module 16 has a second semiconductor light source 74, a second projection lens 60 and a second additional light source 62 as well as a second light guide plate 64. The second projection lens 60 has a second optical axis 66 and a second light entry surface 54, which can be illuminated with the second additional light source 62 through the second light guide plate 64. The second additional light source 62 is arranged on a narrow side of the second light guide plate 64 such that light emanating from the second additional light source 62 enters the second light guide plate 64 transversely to the second optical axis 66.The second light guide plate 64 has a second front emission side 68 facing the second projection lens 60 and a second rear deflection side 70 opposite the second front emission side 68, as well as a first part 43 located closer to the second optical axis 66 and a second part 45 located further away from the second optical axis 66. The second light guide plate 64 is arranged in a tilted position in which the first part 43 of the second light guide plate 64 is located further away from the second projection lens 60 along the second optical axis 66 than the second part 45 of the second light guide plate 64. The second light guide plate 64 is not arranged at a right angle to the second optical axis 66, in particular in the vertical section in which the second optical axis 66 also lies.

[0038] A difference between the objects of Figures 2 and 3 on the one hand and the subject of Figures 4 and 5 on the other hand, is that the second projection light module 16 has a mirror cover 72 running from back to front in the motor vehicle headlight 10 and that the second light guide plate 64 is arranged below the mirror cover 72.

[0039] The mirror aperture 72 has a reflective surface facing the second semiconductor light source 74 and the second optical attachment 76, which extends from the rear to the front into the focal region of the second optical attachment 76 and the second projection lens 60. The second optical attachment 76 is a half-shell reflector with an ellipsoidal basic shape. The second semiconductor light source is arranged at a focal point of the half-shell reflector. A second focal point, or focal region, of the half-shell reflector is intersected by the aperture edge 78. The aperture edge 78 of the mirror aperture 72, located in the focal region, is imaged by the second projection lens 60 as the cut-off line of a low-beam distribution running between the right and left.

[0040] Figure 5shows a front view of the second projection light module 16 with the aperture edge 78 of the mirror aperture 72 running between the right and left, the second attachment optics 76 arranged above the mirror aperture 72 and the second light guide plate 64 arranged below the mirror aperture 72.

[0041] With regard to the function and details of the second light guide plate 64 and the additional light generation, the description of the Figures 2 and 3 also for the Figures 4 and 5 .

[0042] As an alternative to using a reflector as the second auxiliary optics 76, the second auxiliary optics 76 can be designed as a lens or light guide. In one embodiment, the light guide plates 28, 64 are preferably made of the same light guide material as the auxiliary optics. This allows the same light color to be achieved with the light guide plates as with the auxiliary optics. This applies in particular when, for example, the first auxiliary light source emits light of the same light color as the first semiconductor light source.

[0043] Other designs, however, provide for deliberately created differences between the light colors, which are primarily used to create light distributions, and the light colors, which are primarily used to evenly illuminate the projection lenses with the additional light.

[0044] For this purpose, a preferred embodiment provides for the use of colored LEDs as additional light sources. These additional light sources advantageously each comprise three LED chips R, G, and B arranged closely next to one another, which together form a second semiconductor light source 74.

[0045] Figure 6shows a top view of such an arrangement. The main radiation direction of this arrangement is perpendicular to the plane of the drawing. Each of these chips R, G, B emits a different, permanently assigned light color, ideally red, green, and blue. By operating the individual LED chips R, G, B at different brightness levels, the color of the light emitted by the additional light source, and thus of the additional light according to the RGB color model, can be adjusted almost freely. For this purpose, the colored LEDs R, G, B are controlled by the control unit 58. As already generally described for light from the additional light sources, the same applies to the colored light from RGB LEDs R, G, B: this light is fed into the light guide plate and deflected by a prism structure on the deflection side of the light guide plate 28, 64 towards an imaging projection lens 24, 60.This could, for example, transform the appearance of a motor vehicle headlight 10 into the appearance of a taillight. When reversing, the low beam and high beam could be switched off, and the associated projection lenses 24, 60 could be temporarily illuminated in red to fulfill a taillight and / or brake light function.

[0046] Figure 7 shows that the light guide plate 28 and / or 64 can be designed entirely or partially from a colored-transparent material as an alternative to the use of colored light sources, and this light guide plate is then fed with a white LED. This applies in particular to the feed area 80 or parts thereof.

[0047] This alternative would result in a fixed colored illumination of the remaining colorless light guide plate that is deliberately different from the light color of the low beam distribution and / or the high beam distribution and thus lead to a correspondingly colored additional light for the illumination of the projection lenses 24, 60.

[0048] Such a light guide plate 28, 64 would be two-colored, which can be manufactured as a so-called two-component (2K) part using a corresponding two-component injection molding process. Specifically, the interface between the two color-different components of the light guide plate 28, 64, together with the light entry surface of the light guide plate 28, 64, can be optimized to ensure uniform colored illumination of the rest of the light guide plate.

[0049] Another variant instead of a two-color light guide plate consists in a coating of the entrance surface of the otherwise colorless light guide plate, the optical properties of which are designed in such a way that it is only transparent to light of a fixed color or wavelength and absorbs or reflects all light of other colors or wavelengths.

[0050] The light guide plate 28, 64 has a narrow side 36, via which light from an additional light source 26, 62 (compare Figures 2 to 4) is fed into the light guide plate 28, 64. The narrow side 36 terminates in a coupling prism which has a trapezoidal cross-section and extends over the height of the prism. The narrow side 36 forms one of the two parallel surfaces of the prism. The surface of the prism parallel to this forms a transition surface with which the area 80 of the feed, which is identical to the prism here, merges into the rest of the light guide plate. The light from the additional light source fed into the light guide plate via the colored area 80 of the feed experiences total internal reflections at the obliquely positioned boundary surfaces of the prismatic area 31, which reduce the aperture angle of the fed-in light. This light is then deflected at a preferably curved edge area into an area of ​​the circuit board which has a flat, tilted central surface.This area is delimited to the rear by a deflecting surface and to the front by a radiating surface. Deflecting elements are arranged in the deflecting surface, which for example have vertically running edges that delimit inclined prism surfaces. The deflecting elements are shaped in such a way that light from the additional light source incident on them from the interior of the light guide plate is deflected by total internal reflection so steeply towards the front radiating surface that it exits the light guide plate there, with the light preferably being emitted obliquely upwards. Deflecting elements in the shape of roller sections are preferably arranged in the radiating surface, which distribute the light exiting from the radiating surface so widely that it homogeneously illuminates the light entry surface of the projection lens following in the beam path. The roller sections preferably extend from the narrow side serving as the light entry side across the entire width of the radiating surface.Convex roller sections and concave roller sections preferably alternate. The surface lines of the roller sections run parallel to each other. In the radiating surface, the surface lines run perpendicular to the optical axis between a left and a right position. The edges of the deflection elements arranged in the deflection surface, however, preferably run between an upper and a lower position, so that the deflection elements and the roller sections run perpendicular to each other.

[0051] Figure 8shows an arrangement comprising a first optical attachment 50, a tilted first light guide plate 28, a first auxiliary light source 26, and a first projection lens. The first light guide plate 28 is characterized by a uniformly curved transition from its emission and deflection sides into the lateral narrow sides 36 serving to feed in the auxiliary light. The narrow side 36 serving to feed in the auxiliary light is preferably located in the light entry plane of the optical attachment 76, 50. In this case, the auxiliary light source(s) and the LEDs serving to generate the headlight light distributions can be arranged on the same flat and rigid circuit board. This applies analogously to the Figures 9 and 10 . Figure 9 shows an arrangement with a light guide plate that is less high in the vertical direction than the light guide plate of the Figure 8 , and the Figure 10shows a further arrangement with a second light guide plate 64 which is less wide in the horizontal direction between right and left than the light guide plate of the Figure 8 , together with a projection lens system instead of a single first projection lens 24 or second projection lens 60. The light guide plate after the Figure 10 It has a bend at the transition between its emission side and its light input side. This allows for narrow emission sides, as the bends require less space for a change in direction than curved transitions.

Claims

1. Motor vehicle headlight (10) comprising a first projection light module (14) which has a first semiconductor light source (22), a first projection lens (24), and a first additional light source (26) as well as a first light guide plate (28), wherein the first projection lens (24) has a first optical axis (30) and a first light entry surface (32) which can be illuminated by the first additional light source (26) through the first light guide plate (28), wherein the first additional light source (26) is arranged on a narrow side (36) of the first light guide plate (28) such that light emanating from the first additional light source (26) enters the first light guide plate (28) transversely to the first optical axis (30) and the first light guide plate (28) has a front emission side (38), facing the first projection lens (24), and a first rear deflection side (40), opposite the first front emission side (38), as well as a first part (42) located closer to the first optical axis (30) and a second part (44) located further away from the first optical axis (30), wherein the first light guide plate (28) is arranged in a tilted position in which the first part (42) of the first light guide plate (28) is located further away from the first projection lens (24) along the first optical axis (30) than the second part (44) of the first light guide plate (28), characterized in that, at deflection structures arranged in the first rear deflection side (40) of the first light guide plate (28), the additional light (34) is deflected so steeply to the first front emission side (38) of the first light guide plate (28) that it emerges there in a uniformly distributed manner, and in that the emitted additional light (34) is scattered at least in the vertical direction by scattering structures (52) arranged in the first front emission side (38) such that it illuminates the first light entry surface (32) of the first projection lens (24) in a uniformly distributed manner.

2. Motor vehicle headlight (10) according to claim 1, characterized in that the first projection light module (14) is a high-beam module.

3. Motor vehicle headlight (10) according to claim 1, characterized by a second projection light module (16) which has a second semiconductor light source (74), a second projection lens (60), and a second additional light source (62) as well as a second light guide plate (64), wherein the second projection lens (60) has a second optical axis (66) and a second light entry surface (54) which can be illuminated by the second additional light source (62) through the second light guide plate (64), wherein the second additional light source (62) is arranged on a narrow side of the second light guide plate (64) such that light emanating from the second additional light source (62) enters the second light guide plate (64) transversely to the second optical axis (66) and the second light guide plate (64) has a front emission side (68), facing the second projection lens (60), and a second rear deflection side (70), opposite the second front emission side (68), as well as a first part (43) located closer to the second optical axis (66) and a second part (45) located further away from the second optical axis (66), and in that the second light guide plate (64) is arranged in a tilted position in which the first part (43) of the second light guide plate (64) is located further away from the second projection lens (60) along the second optical axis (66) than the second part (45) of the second light guide plate (64).

4. Motor vehicle headlight (10) according to claim 3, characterized in that the second projection light module (16) comprises a mirror shutter (72) extending from back to front in the motor vehicle headlight (10) and in that the second light guide plate (64) is arranged below the mirror shutter (72).

5. Motor vehicle headlight (10) according to claim 3, characterized in that the first light guide plate (28) and / or the second light guide plate (64) has at least one colored region.

6. Motor vehicle headlight (10) according to claim 5, characterized in that the colored region is a light entry region of the otherwise colorless transparent light guide plate.

7. Motor vehicle headlight (10) according to claim 5, characterized in that the colored region is a color-coated light entry region of the otherwise colorless transparent light guide plate.

8. Motor vehicle headlight (10) according to any of the preceding claims, characterized in that the light color of the first additional light source (26) is fixed and differs from the light color of a high beam and / or a low beam.

9. Motor vehicle headlight (10) according to any of claims 3 to 7, characterized in that the light color of the first additional light source (26) and / or second additional light source (62) is controllably variable and can differ from the light color of a high beam and / or a low beam.

10. Motor vehicle headlight (10) according to claim 9, characterized in that the first additional light source (26) and / or second additional light source (62) has individually controllable, differently colored light-emitting diodes (R, G, B).

11. Motor vehicle headlight (10) according to claim 10, characterized in that the individually controllable, differently colored light-emitting diodes comprise a red-light-emitting light-emitting diode (R), a green-light-emitting light-emitting diode (G) and a blue-light-emitting light-emitting diode (B).

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