Motor vehicle headlamp

Abstract

The invention relates to a motor vehicle headlamp (2) for use in a motor vehicle for illuminating a region in front of the motor vehicle with a predetermined light distribution, comprising a light source (20) for emitting light (22), a primary optical element (24) for focusing the emitted light (22) in an intermediate image plane (30) of the headlamp (2), and a secondary optical element (28) for imaging the light (52) from the intermediate image plane in the region in front of the motor vehicle and for generating the predetermined light distribution. It is proposed that the intermediate image plane (30) is divided into a plurality of sub-regions (50) illuminated by the light (26) of the primary optical element (24), and that the primary optical element (24) is designed such that the light (52) from each sub-region (50) of the intermediate image plane (30) illuminates at least 80% of an active surface (54) of the secondary optical element (28).

Description

[0001] This invention relates to a motor vehicle headlight used in a motor vehicle for illuminating the area in front of the vehicle with a predetermined light distribution. The headlight includes: a light source for emitting light; a main optical element for focusing the emitted light onto an intermediate image plane of the headlight; and a secondary optical element for imaging the light from the intermediate image plane onto the area in front of the vehicle and generating the predetermined light distribution. Therefore, this headlight is a so-called projection system, and the headlight module included therein is formed as a so-called projection module.

[0002] Modern high-power headlights—which feature dense semiconductor light sources such as LEDs (especially high-power LEDs) and laser light sources (especially laser diodes)—can also pose a hazard to the human eye when observing the emitted light radiation at close range under normal conditions, that is, during their regular operation and in the absence of defects in the light source (e.g., converter layers, etc.). Assessments of such hazards are standardized in standards DIN (German Institute for Standardization) / IEC (International Electrotechnical Commission) 60825 and DIN / IEC 62471. Detailed information on this topic can be found in publications such as:

[0003] -Schulmeister, Karl: Classification of Extended Source Products Conforming to IEC 60825-1, Paper #C101, 2015 Meeting Minutes, pp. 271-280;

[0004] -Schulmeister, Karl, Daem, Jan: Classification of laser light sources according to IEC 60825-1 standard, 3rd edition, paper #401. 2017 Meeting Minutes, pp. 174-180.

[0005] The subject matter of this patent application makes explicit references to the aforementioned publications and is therefore included in the disclosure of this invention. Accordingly, this also applies to the aforementioned laser standards DIN / IEC 60825 and DIN / IEC 62471.

[0006] More information can be found in the article "A Study of the C6 Factor (“Appearing Sources”) for Laser Classification" published in the first issue of *Laser Journal*, 2018, pages 20-21. This article states that laser classification is based on the acceptable radiation limit (GZS), as described in the DIN EN 60825-1 standard. In this standard, the GZS values ​​for all laser classes are summarized in tabular form as a function of wavelength, emission duration, and correction factors C1 to C7. In this table, the C6 factor specifically refers to Class 1, Class 1M, Class 2, Class 2M, and Class 3R, and the wavelength range from 400 nm to 1400 nm. For example, a laser with a wavelength λ = 680 nm, an exposure time t = 100 s, and a limit GZS = 5.10... -3 Lasers with a C6 W rating (see Table 7 of the aforementioned standard) are classified as Class 3R. As in this example, in all other cases, the GZS value for retinal thermal hazards increases linearly with C6. In practical applications, the maximum value can reach C6 = 66.

[0007] For the selected practical example, this means that, under certain conditions, the theoretical limit for Class 3R lasers can reach 330 mW (Note: C6 cannot be less than 1 by definition, see below). To determine the C6 factor, the apparent angle α of the laser source is needed. This angle α is the angle at which the observer can see the apparent laser source. Here, "apparent" means that the location of the light source does not necessarily have to be the laser itself, but can also be behind it (the angle α is often confused with the divergence angle of laser radiation). Angle α depends on the distance from the laser source and is based on the adaptability of the eye.

[0008] For classification, α is downward restricted to α. min = 1.5 mrad; the upward limit of α depends on the exposure duration (Einwirkungsdauer), which is α max (t), but the maximum is 100 mrad. The C6 factor is determined according to Table 9 of DIN EN 60825-1 standard, i.e., C6 = α / α min Therefore, it is location-dependent. Finally, classification is performed at the farthest distance from the laser source (that is, at the location where the ratio of acceptable radiation to GZS has a maximum). This distance is always ≥100mm, depending on the minimum adaptability of the glasses.

[0009] Section 5.4.3 of the DIN EN 60825-1 standard details the measurement method for classifying lasers with C6>1. This is based on simulating (apparently) the imaging of the laser source on the retina through experiments (including adaptation) at different distances between the laser and the eye. This is typically achieved using a measuring device in which a lens (“eye”) positioned on an optical track is placed in front of the laser at different distances, and a clear image is respectively set on a CCD array (“retina”) arranged behind it. Subsequently, the facing angle α can be derived from the geometry of the image.

[0010] This image of laser radiation on the retina, obtained through experimental simulation, yields a GZS value, taking into account real-world risks. It differs from the significantly less complex simple classification standard, where, in the "worst-case" scenario, C6 = 1, and the image is formed on the retina with a small focal point and correspondingly high intensity. This simple "standard classification method," where C6 = 1 (see the aforementioned standard), is essentially usable in any situation. However, the resulting laser category may have a high safety margin. There are many applications where the maximum possible laser power within a laser category should be fully utilized (e.g., distance measurement, velocity measurement).

[0011] In these cases, an "extended method" for C6 > 1 is required. This applies to lasers with a radiative divergence angle > 1.5 mrad within the aforementioned wavelength range. Typically, such lasers include linear lasers, laser diode arrays, multilayer laser diodes, laser sources with diffusers, and may also include laser pointers. In practice, a C6 factor of 10 has been achievable to date.

[0012] Based on the above-mentioned prior art, the object of the present invention is to design and further develop a motor vehicle headlight of the above type so as to minimize the harm to the eyes of observers near the headlight under normal conditions (that is, during the normal operation of the headlight and when there is no defect in the light source).

[0013] To address this issue, a motor vehicle headlight with the technical features of claim 1 is proposed. Specifically, based on the aforementioned type of headlight, a method is proposed in which the intermediate image plane is divided into multiple sub-regions illuminated by light from a primary optical element, and the primary optical element is designed such that light from each sub-region of the intermediate image plane illuminates the action surface of a secondary optical element. At least 80% of ().

[0014] Therefore, this invention proposes a motor vehicle headlight or headlight module that reduces hazard by maximizing the size of the apparent light source under normal operating conditions. Thus, it is a method for passively reducing the possibility of hazard. Through the design of the primary optical element proposed according to this invention, the illumination of the active surface of the secondary optical element or projection optical element can be selectively controlled to maximize the size of the apparent light source. The "active surface" of the secondary optical element is the portion of the secondary optical element through which light passes during normal operation of the motor vehicle headlight or headlight module, participating in the formation of the resulting headlight beam distribution. The "active surface" does not include, for example, the edge region of the secondary optical element, which is used to hold the secondary optical element within the headlight module. Furthermore, for the secondary optical element formed as a projection lens, it is perpendicular to the optical axis of the headlight module and has an off-circular shape, such as elliptical, triangular or quadrilateral, diamond-shaped, rhomboid, kite-shaped, or teardrop-shaped, so that the light used to generate the beam distribution passes only through the central region of the projection lens, which forms the "active surface," wherein the lens region outside the central region is not part of the "active surface."

[0015] The intermediate image plane is an imaginary plane, preferably located within the focal point or focal cloud of the secondary optical element. The intermediate image plane preferably extends perpendicularly to the axis, at least around the axis of the headlamp (e.g., the optical axis). The intermediate image plane can be formed as a planar plane or a curved plane.

[0016] The light source can essentially consist of any light source. For example, it is conceivable that the light source includes at least one arbitrary semiconductor light source (e.g., an LED). Particularly preferred is that the light source includes a laser semiconductor light source (a so-called laser diode). The advantages of the present invention are particularly significant for semiconductor light sources, because without the measures proposed according to the invention, the risk of harm to the observer's eyes is relatively high. With the present invention, the possibility of harm is significantly reduced during the normal, trouble-free operation of the semiconductor light source.

[0017] This invention proposes that, in order to increase the size of the surface light source and thereby reduce its harmfulness, radiation should be scattered to facilitate the formation of the maximum light distribution in order to achieve maximum lens illumination, thereby producing the largest possible image of the surface light source (C6 factor or C6 only, according to DIN / IEC 60825 or DIN / IEC 62471). The key here is that the secondary optics or projection optics are illuminated as extensively and uniformly as possible. That is, ideally, each sub-region in the intermediate image plane illuminates the projection optics with the maximum possible numerical aperture. Wherein, the numerical aperture A... N A is obtained by multiplying the sine of the half-object side opening angle (receiving angle) α with the refractive index n of the material between the objective lens and the focal point:N = n·sinα. Ideally, light from each sub-region of the intermediate image plane completely illuminates the entire optically active surface of the secondary optical element. However, in practice, it has been shown that when light from the intermediate image plane illuminates at least 80% of the active surface of the secondary optical element, it is possible to achieve a significant increase in the apparent image of the light source and a significant reduction in the resulting potential for harm.

[0018] The size of a visible light source is an important factor in evaluating lamp functionality related to eye hazards, because a larger visible light source distributes radiation over a larger area of ​​the retina, thus reducing harm. Therefore, laser standards allow for higher limits on light sources with larger C6 values. This allows for the use of light sources with greater luminous intensity, enabling a larger amount of light to be used for headlight functionality, while the risk of hazard to the observer remains within acceptable limits even when the headlight is operating normally.

[0019] Other preferred embodiments of the invention are the subject of the dependent claims. Therefore, according to another advantageous improvement, each sub-region of the intermediate image plane includes at least one point of the intermediate image plane. The sub-regions of the intermediate image plane can also each include one or more points of the intermediate image plane. If each of these sub-regions includes only one point, then each point of the intermediate image plane also illuminates at least 80% of the working surface of the secondary optical element. However, it is preferable that each of these sub-regions also includes multiple points of the intermediate image plane. Accordingly, the primary optical element is also designed such that the light from all points of each sub-region of the intermediate image plane collectively illuminates at least 80% of the working surface of the secondary optical element. It is not required that each individual point of the intermediate image plane illuminates at least 80% of the working surface of the secondary optical element.

[0020] The primary optical element for focusing light emitted from the light source can be formed in any manner. For example, it is conceivable that it includes one or more solid secondary optical elements (Vorsatzoptik) made of a transparent material (e.g., glass or plastic), which focus the passing light beam by means of refraction upon entering and exiting the secondary optical elements and / or by means of total internal reflection at one or more interfaces of the secondary optical elements. According to a preferred embodiment, the primary optical element includes a reflector. This reflector can be specifically designed as a free-form reflector whose reflecting surface is designed according to calculations or computer simulations, thereby reflecting light emitted from the light source into the intermediate image plane of the headlamp or headlamp module, such that light from each sub-region of the intermediate image plane illuminates at least 80% of the working surface of the secondary optical element.

[0021] The secondary optical element used to image light from the intermediate image plane in the forward region of a motor vehicle and to generate the light distribution of the headlights can be designed in any manner. For example, it is conceivable that the secondary optical element includes one or more imaging reflectors. According to a preferred embodiment, the secondary optical element includes a projection lens. This projection lens has an active surface on the side facing the intermediate image plane, which is illuminated by at least 80% of each sub-region of the intermediate image plane.

[0022] Therefore, light from a sub-region of the intermediate image plane can illuminate the working surface of the secondary optical element with a particularly large area and uniformly. It is advantageous if the primary optical element is designed such that each illuminated sub-region in the intermediate image plane is illuminated over the largest possible angular range. Furthermore, it is proposed that the primary optical element be designed such that the focused light has a beam that crosses between the primary optical element and the intermediate image plane. In this way, the beam transmitted from the primary optical element to the intermediate image plane is sufficiently diverged to illuminate at least 80%, preferably the entire working surface, of the secondary optical element as uniformly as possible. Therefore, the objective is to illuminate each sub-region of the intermediate image plane over the largest possible angular range, and also to illuminate as much of the working surface of the secondary optical element, i.e., at least 80%, preferably the entire working surface, of the secondary optical element, with light from each sub-region of the intermediate image plane. This can be achieved particularly well if at least a portion (preferably most) of the beam from the primary optical element crosses each other before reaching the intermediate image plane.

[0023] According to an advantageous improvement of the invention, the optically functional surface of the main optical element—for example, the reflecting surface of a reflector or the light-emitting surface of an additional optical element—is... —It is divided into multiple regions, and the main optics are designed such that each sub-region of the intermediate image plane is illuminated by as many different regions of the main optics as possible. In particular, the main optics are designed such that each sub-region of the intermediate image plane is illuminated by at least 80% of the different regions of the main optics.

[0024] According to another advantageous improvement of the invention, the main optical element has a microstructure or microfacet treatment on its optically active surface, such as the reflecting surface of a reflector or the emitting surface of an additional optical element. Different regions of the main optical element each comprise a plurality of microstructure elements or microfacets, and each region of the main optical element illuminates a plurality of sub-regions of the intermediate image plane. The microstructures or microfacets consist of individual microscattering elements having a height deviation relative to the basal plane in the micrometer range (approximately <500 μm, preferably <300 μm, particularly preferably <100 μm, especially 10 to 50 μm). The surface dimensions of the individual scattering elements in terms of width and length may also be outside the micrometer range, for example, in the range of 0.1 to 1.0 mm, preferably 0.1 to 0.5 mm. Preferably, the microscattering elements are arranged side-by-side on at least a portion of the optically active surface of the main optical element.

[0025] In the case of a transparent additional optical element made of a solid material, the micro-scattering element preferably formed on the light-emitting surface of the additional optical element is designed to refract the light emitted from the additional optical element through it in a desired manner, particularly in a desired direction. In the case of a reflector, the micro-scattering element preferably formed on the reflective surface of the reflector is designed to reflect the light incident upon it in a desired manner, particularly in a desired direction.

[0026] Microscattering elements do not simply scatter light from a light source randomly. Instead, they have specially formed and precisely defined dimensions and shapes to redirect light focused by the main optics via a surface with optical effect, or by microscattering elements arranged on that surface, towards one or more desired directions, particularly towards a desired sub-region of the intermediate image plane. Each region of the main optics has multiple microscattering elements, such that at least 80% of the sub-region of the intermediate image plane is illuminated not by each individual microscattering element, but by each individual region of the main optics, where multiple microscattering elements work together in each region of the main optics to achieve the desired illumination of the sub-region of the intermediate image plane.

[0027] According to another advantageous improvement of the invention, the main optical element has a plurality of facets on its optically active surface, wherein each facet of the main optical element illuminates a plurality of sub-regions of the intermediate image plane. In the case of a transparent supplementary optical element made of a solid material, the facets formed on the light-emitting surface of the supplementary optical element are preferably designed to refract light passing through them in a desired manner, particularly in a desired direction. In the case of a reflector, the facets formed on the reflecting surface of the reflector are preferably designed to reflect light incident upon it in a desired manner, particularly in a desired direction.

[0028] The facets have specially formed and precisely defined dimensions and shapes to redirect light focused by the main optics via an optically active surface or by facets arranged on that surface into one or more desired directions, particularly into desired sub-regions of the intermediate image plane. The active surface of the facet can have a certain inclination relative to the base plane of the main optics. The active surface can be designed to be planar or curved. The curvature of the active surface can vary. Each region of the main optics is formed by facets such that at least 80% of the sub-regions of the intermediate image plane are illuminated by each individual facet of the main optics, wherein the desired illumination in the intermediate image plane is achieved through individual facets.

[0029] In a preferred variant of the invention, the headlight has a beam stop (strahlenblende), particularly a specular stop (spiegel-blende), between the primary and secondary optical elements. The secondary optical element is designed such that at least one edge of the beam stop images in the forward region of the vehicle, thereby creating a light-dark boundary in the headlight's light distribution. The beam stop can be a vertical stop extending in the intermediate image plane, with its upper edge positioned in the region of the intermediate image plane and thus in the region of the focal point of the secondary optical element. Alternatively, the beam stop can be formed as a horizontal stop, particularly as a substantially horizontal specular stop extending generally perpendicular to the intermediate image plane, with its leading edge at least partially positioned in the region of the intermediate image plane and thus in the region of the focal point of the secondary optical element. The edge of the stop, imaged by the secondary optical element, can have straight, stepped, and / or curved extensions. The secondary optical element images its upper or leading edge in the forward region of the vehicle, thereby creating a horizontal light-dark boundary in the light distribution. Alternatively, the beam stop can also be formed as a vertical stop, particularly as a vertical mirror stop, which extends perpendicular to the intermediate image plane and spaced from the axis (particularly the optical axis of the headlight) and preferably substantially parallel to the axis. The leading edge of the beam stop is arranged in the region of the intermediate image plane and thus in the focal plane of the secondary optical element, and is imaged by the secondary optical element in the forward region of the vehicle to produce a vertical boundary between light and dark areas (e.g., partial high beam or marker light) in the light distribution.

[0030] Advantageously, the primary optical element is configured to illuminate not only the working surface of the secondary optical element across the entire plane, but also to provide the most uniform illumination possible. Preferably, the light incident on the secondary optical element has approximately a constant illumination intensity across the entire illuminated surface of the secondary optical element. This further reduces the risk of hazard.

[0031] Another advantageous design according to the invention proposes that the headlight has a transparent diffuser plate arranged in or near the intermediate image plane, extending in or parallel to the intermediate image plane. This diffuser plate ensures that light from the primary optical element illuminates as uniformly as possible the maximum possible portion of the working surface of the secondary optical element, preferably at least 80% of the working surface of the secondary optical element, and particularly preferably the entire working surface of the secondary optical element. To this end, the widening angle of the diffuser plate decreases towards its edge. This means that, preferably, the widening angle decreases towards the outer edge, starting from its maximum value located at the center of the diffuser plate.

[0032] Other features and advantages of the present invention will be described in detail below with reference to the accompanying drawings. The features shown in the drawings and described below can each independently serve as essential features of the invention. Furthermore, the invention includes any combination of features, even if such combinations are not explicitly shown in the drawings and not explicitly described below. The drawings are as follows:

[0033] Figure 1 It is a simplified graphical explanation of power measurement;

[0034] Figure 2 This is another simplified illustration illustrating the method used to measure the C6 value of a light source;

[0035] Figure 3 It is a headlight module of a motor vehicle headlight known from existing technology;

[0036] Figure 4 This is a headlight module for a motor vehicle headlight according to the present invention;

[0037] Figure 5 The headlight module according to the present invention; and

[0038] Figure 6 The present invention relates to a motor vehicle headlight.

[0039] Figure 6 The headlight 2 is a motor vehicle headlight according to the present invention, generally indicated by reference numeral 2. The headlight 2 is designed to be installed in a corresponding mounting opening on the front side of a motor vehicle. The headlight 2 includes a housing 4, which is preferably made of plastic. In the light emission direction 6, the housing 4 has a light emission opening 8, which is closed by a transparent cover plate 10. The cover plate 10 is preferably made of plastic or glass. It can be designed with or without optical elements (e.g., prisms or cylindrical lenses) for scattering passing light. A headlight module 12 is arranged inside the housing 4, which... Figure 6 The image is shown only schematically and can be referenced below. Figure 4 and 5 A detailed explanation will be provided.

[0040] The headlight module 12 is used to generate a light distribution for any headlight function or lamp function (so-called main lamp function) or a portion thereof. The headlight function may be, for example, a low beam, a high beam, a fog light, or any adaptive light distribution (e.g., in the form of an inclement weather light, a city light, a rural road light or an intercity street light, a highway street light, a so-called continuous high beam (also known as a glare-free high beam or a partial high beam), or a so-called marker light), or a part of such a lamp function.

[0041] In addition to the headlight module 12 shown, at least one other light module (not shown) can be arranged inside the housing 4 of the headlight 2. This module can either generate other headlight functions independently or together with the headlight module 12. This at least one other light module can be formed as a so-called reflector module or a projection module. Of course, this at least one other light module can also be formed as the headlight module according to the present invention. Furthermore, at least one light-emitting module can be arranged in the housing 4, which implements any light-emitting function (e.g., flash, daytime running light, position light, parking light).

[0042] An optical module 12 known from the prior art is described below according to Figure 3 A detailed description is provided. The headlight module 12 is preferably configured as a projection module. In the projection module, the light 22 emitted from the light source 20 is focused and directed onto the light emission direction 6 by means of a main optical element 24, for example, in the form of a reflector or lens element (so-called additional optical element). When a reflector is used, it generally has an elliptical basic shape. A secondary optical element 28 is provided in the beam path of the light 26 focused by the main optical element 24, which is, for example, in the form of a projection lens or projection reflector. This secondary optical element images the intermediate light distribution generated by the main optical element 24 in the intermediate image plane 30 (preferably corresponding to the focal plane of the secondary optical element 28, which often coincides with the focal plane of the main optical element 24) as the light distribution obtained by the headlight function of the headlight 2 in the forward area in front of the vehicle (especially on the road surface). In the beam path of the light 26 focused by the main optical element 24, preferably in the intermediate image plane 30, an aperture device 32 with an edge 34 can be provided, which blocks or redirects a portion of the focused light 26, and its edge 34 is projected onto the road surface by the secondary optical element 28 as the light-dark boundary of the light distribution controlled by the aperture.

[0043] exist Figure 3 In the image, a vertical aperture 32 with an upper edge 34 is drawn using dashed lines. Similarly, in... Figure 3 In the diagram, a mirror stop 32', having a leading edge 34', is drawn in dashed lines as an alternative to the vertical stop 32. This mirror stop 32' has a substantially horizontal extension that is generally parallel to the axis 36 (specifically the optical axis) of the light module 12 or the headlight 2. The mirror stop 32' may have a maximum deviation of approximately 20° from the horizontal plane.

[0044] The light source 20 preferably comprises any semiconductor light source chip, particularly an LED chip or a laser diode chip. The light source 20 preferably emits white light, which, in the case of an LED chip or laser diode chip, is generated in such a manner that at least one LED or laser diode emits light of a first wavelength (e.g., blue light or ultraviolet light), which strikes a converter material (e.g., a light-emitting material) of the chip, which converts at least a portion of the incident light into light having at least one other wavelength (e.g., blue light converted to yellow light, or ultraviolet light converted to both blue and yellow light, or to both red and green light). White light is obtained by additive color mixing of the first wavelength light with at least one other wavelength light.

[0045] Modern high-power headlights 2—which have dense semiconductor light sources 20 such as LEDs (especially high-power LEDs) and laser light sources (especially laser diodes)—can also pose a hazard to the human eye when observing the emitted light radiation at close range under normal conditions, that is, during their regular operation and in the absence of defects in the light source 20 (e.g., converter layers, etc.). The assessment of such hazards is standardized in DIN / IEC 60825 and DIN / IEC 62471. Accordingly, the C6 factor is used as a measure of the degree of hazard potential of the semiconductor light source. It depends on the size of the apparent light source. There are different methods for determining the C6 factor or the size of the apparent light source. For illustration, refer to [reference] below. Figure 1 and 2 A simple measurement method is illustrated below:

[0046] Light source 20 emits light radiation 22. In the case of headlight 2, the last optical element of the lamp function is used instead of the actual light source 22. Furthermore, in the case of projection module 12, the illuminated surface of secondary optical element 28 is used. The power of the light 22 emitted from light source 20 is measured by a measuring pupil 38 having an opening diameter of, for example, 7 mm. For example, for light source 20 in the form of a type 2 laser diode, the limit of permissible radiated power measured with a 7 mm pupil 38 at C6=1 is 1 mW.

[0047] The measuring pupil 38 is positioned at the point on which the highest radiant power can be measured (i.e., the "highest limit point" according to DIN EN60825-1). Then, to determine the size of the apparent light source, an image 42 of the light source 20 is generated on the measuring screen 44 via the measuring pupil 38 and lens 40. This image 42, with minimal expansion, determines the size of the apparent light source in mrad. For example, if the light source 20 is approximately point-like, only a very small image 42 can be generated on the measuring screen 44, and the C6 factor for such a light source 20 is very small. The same applies to a light source 20 that generates a parallel beam of radiation, as such a beam will also produce a very small image 42.

[0048] This invention provides a motor vehicle headlight 2, wherein the headlight module 12 is designed in a specific manner. The headlight module 12 of the headlight 2 according to the invention is described below in conjunction with... Figure 4 and 5 To be detailed in detail. The headlight 2 or headlight module 12 can have the same characteristics as described above and... Figure 6 The headlight 2 shown in the image or as described above and in Figure 3 The same components as the headlight module 12 shown. Specifically, based on the headlight 2 known from the prior art, the intermediate image plane 30 is divided into multiple sub-regions 50 or has multiple sub-regions 50, these sub-regions being illuminated by focused light 26 from the main optics 24, and the main optics 24 is designed such that light 52 from each sub-region 50 of the intermediate image plane 30 illuminates at least 80% of the working surface 54 of the secondary optics 28. Figure 4 For example, two sub-regions 50 are drawn as black circles. According to... Figure 4 It can be clearly seen that light 52 from each sub-region 50 of the intermediate image plane 30 illuminates a large portion of the working surface 54 of the secondary optical element 28. This working surface 54 can encompass all or only a portion of the secondary optical element 28. In this way, it is possible to achieve the largest possible apparent light source on the secondary optical element 28, achieve the largest possible C6 factor, and thereby minimize the potential for harm to the light source 20.

[0049] The present invention also proposes a headlight module 12 for a motor vehicle headlight 2 or such headlight 2, wherein hazard is reduced by maximizing the size of the apparent light source under normal operating conditions. Therefore, it is a method for passively reducing the likelihood of hazard. Through the design of the primary optical element 24 proposed according to the present invention, the illumination of the working surface 54 of the secondary optical element 28 or the projection optical element can be selectively controlled to maximize the size of the apparent light source.

[0050] The light source 20 can be composed of virtually any light source. For example, it is conceivable that the light source 20 includes at least one arbitrary semiconductor light source (e.g., an LED). It is particularly advantageous that the light source 20 includes a laser semiconductor light source (a so-called laser diode). The advantages of the present invention are particularly significant for semiconductor light sources, because reducing the potential for harm is especially important for semiconductor light sources in the form of laser diodes.

[0051] The present invention proposes that, in order to increase the size of the surface light source and thereby reduce its harm, light radiation 26, 52, which helps to form the maximum light distribution, should be scattered to achieve maximum lens illumination, thereby producing the largest possible image of the surface light source. The secondary optical element or projection optical element 28 should be illuminated as extensively and uniformly as possible. That is, ideally, each sub-region 50 in the intermediate image plane 30 illuminates the projection optical element 28 with the maximum possible numerical aperture. Wherein, the numerical aperture A... N A is obtained by multiplying the sine of the half-object side opening angle (receiving angle) α with the refractive index n of the material between the objective lens and the focal point: N = n·sinα. Ideally, light 52 from each sub-region 50 of the intermediate image plane 30 completely illuminates the entire optically active surface 54 of the secondary optical element 28. However, in practice, it has been demonstrated that when light 52 from each sub-region 50 of the intermediate image plane 30 illuminates at least 80% of the active surface 54 of the secondary optical element 28, a significant increase in the apparent image of the light source and a significant reduction in the resulting potential for harm can be achieved.

[0052] The size of the apparent light source is an important factor in evaluating lamp function in relation to eye hazards, because a larger apparent light source distributes radiation over a larger area of ​​the retina, thus reducing hazard. Therefore, laser standards allow for higher limits on light sources 20 with a larger C6. This allows for the use of a light source 20 with greater luminous intensity, resulting in a greater amount of light available for producing the lamp function of the headlight 2, while the risk of hazard to the observer remains within acceptable limits even when the headlight 2 is operating normally.

[0053] This invention describes a method for minimizing the potential hazards posed by the light radiation from a headlight module 12 or a motor vehicle headlight 2. The headlight module 12 can be designed (as described) as a projection system with a laser-excited light source 20. By cleverly distributing light 26 in the intermediate image plane 30 (the object plane of the secondary optics 28), the size of the apparent light source is maximized. According to laser standards (e.g., DIN / IEC 60825), this reduces the potential hazards caused by light radiation because the maximum possible illumination intensity on the retina of the human eye is reduced. To this end, the primary optics 24 are designed such that each illuminated sub-region 50 in the intermediate image plane 30 is illuminated over the largest possible angular range. This invention improves the safety of laser headlights without loss or additional components.

[0054] According to Figure 3 The beam paths of beams 22, 26, and 52 of the known optical module 12, illustrated by an example, clearly show that light source 20 emits light 22, which is redirected by reflector 24 to the intermediate image plane 30. The intermediate ray distribution on the intermediate image plane 30 is imaged onto the road surface by projection lens 28. The sub-region 50 plotted in the intermediate image plane 30 indicates that, after being imaged by projection lens 28, it significantly contributes to the measurement of the pupil 38. Figure 3 In this context, the C6 factor has a relatively small value and a relatively high potential for harm.

[0055] To increase the C6 factor, according to Figure 4 and 5 The main optical element 24 of the light module 12 of the headlight 2 of the present invention is preferably designed such that radiation 52 (which emanates from each sub-region 50) illuminates a large portion, preferably at least 80%, and ideally the entire effective surface 54 of the projection lens 28. Thus, the luminous surface in the intermediate plane 30 appears as a Lambert'scher radiator scattering light. Figure 4 and 5 In this context, the apparent size of the light source 20 (the surface illuminated on the projection lens 28) appears significantly larger than that of the surface illuminated on the projection lens 28. Figure 3 The apparent size in. Figure 4 and 5 In the case shown, the size of the light source 20 on the retina of the observer's eye can be determined based on the imaging ratio of the projection lens 28 and the diameter of the sub-region 50.

[0056] To achieve the effects according to the invention, it is necessary to design the main optical element 24 such that each point in the intermediate image plane 30 is illuminated by as many different regions of the reflector 24 as possible. This can be achieved by using microstructures on the main optical element 24 or by microfacetization of the main optical element 24. Conventional microfacetization of the main optical element 24 can also improve the C6 factor of the projection module 12. Preferably, each sub-region 50 in the intermediate image plane 30 is illuminated by each facet of the main optical element 24. Importantly, the light 52 emitted from each sub-region 50 of the intermediate image plane 30 fills the pupil 38 after passing through the projection lens 28. When assigning a numerical aperture (NA) to the projection lens 28, it is appropriate that each point in the intermediate image plane 30 should be illuminated with a NA typically between 80% and 110% of the projection lens's NA.

[0057] NA_projection lens = lens diameter / (2 × focal length).

[0058] Generally, for the headlight module 12 according to the invention, particularly for microstructures or microfacets optionally mounted on the optically active surface of the main optics 24, the requirements for the resulting light distribution must first be met, even if this hinders further increases in the C6 factor. Depending on the desired light distribution of the headlight 2, it is possible to divide the area of ​​the intermediate image plane 30 illuminated by the beam 26 of the main optics 24 into multiple sub-regions 50. Similarly, according to the invention, the light 52 of each sub-region 50 illuminates the projection lens 28, that is, at least 80% of the active surface 54 of the projection lens 28. It is particularly advantageous to use multiple light sources 20 with possibly multiple allocated main optics 24, which illuminate the entire secondary optics 28.

[0059] In one variant, the main optical element 24 includes one or more freeform optical elements (e.g., additional optical elements with freeform lenses). To further improve illumination, scattering structures / microstructures can also be additionally mounted on these freeform optical elements. Even though only the beam path in the horizontal plane is shown in the figures, this naturally applies equally (and simultaneously) to the beam path in the vertical plane. The maximum possible C6 factor is obtained when the illumination using the projection optical element 28 (with radiation falling into the measuring pupil 38) is optimal in both the horizontal and vertical directions.

[0060] It should be noted that the radiated power of each relevant sub-region 50 (i.e., with a certain minimum power) is dispersed from the intermediate image plane 30 through the exit surface of the projection lens 28. When the measuring pupil 38 (or the observer's eye) is positioned directly in front of the headlight 2 (at a distance of less than 200 mm), only a portion of the radiated power falls into the 7 mm-sized measuring pupil 38, because the diameter of the projection lens 28 is approximately 30 to 100 mm. This further reduces hazards unrelated to the C6 factor.

[0061] Based on the distance 56 measured from the pupil 38 to the imaginary intermediate plane (lens plane 58) of the projection lens 28 (see... Figure 4 In the case of [the previous sentence], it may also be advantageous to generate multiple sub-regions 50, each with a small radiative divergence angle, within the intermediate image plane 30, in order to optimize the C6 factor.

[0062] To enhance lens illumination and thus increase the C6 factor, a mirror stop 32' (which has a particularly horizontal extension) can be used instead of the vertical shutter stop 32 (see [reference]). Figure 3 By means of the aperture stop 32', the illumination of the projection lens 28 through a portion of the beam path 26 can be relatively easily increased.

[0063] Further optimization of the C6 factor is possible when the intensity distribution in the lens plane 58 is made as uniform as possible by means of the principal optical element 24 designed according to the invention, or when the intensity distribution of the radiation 60 (which falls into the measuring pupil 38) is distributed as uniformly as possible on the surface of the lens plane 58. This is particularly advantageous when the measurement is performed in a position where the measuring pupil 38 is very close to the lens 28.

[0064] An additional transparent scattering plate 62 can be inserted in the intermediate image plane 30 (see...) Figure 4The scattering structure 62 amplifies the radiation 26 at a certain scattering angle. Preferably, this scattering angle is chosen such that at least 80% (preferably the entire) of the secondary optical element 28 is illuminated by the illuminated point of the scattering plate 62. In an advantageous implementation of the scattering plate 62, the intensity (amplification angle) is not constant on the scattering plate 62, but decreases towards the outer edge of the scattering plate 62 or the outer edge of the image / object field, thereby reducing the beam amplification of the passing light 26 at the edge points, and thus not excessively affecting the efficiency of the entire system (lamp module 12 or headlight 2). Without this decreasing beam amplification towards the edge, there is a risk that a portion of the light 26, 52 (passing through the edge area of ​​the scattering plate 62) will pass by the secondary optical element 28. Furthermore, a potentially advantageous design is that the scattering structure 62 does not act isotropically, but rather deflects the passing light 26 more towards the secondary optical element 28, for example, at the edges.

[0065] It is suggested here that the main optical element 24 has microstructures or microfacets on its optically active surface 24' (e.g., the reflective surface of a reflector), wherein different regions of the main optical element 24 each include multiple microstructures or microfacets, and each region of the main optical element 24 illuminates multiple sub-regions 50 of the intermediate image plane 30. The microstructures or microfacets consist of individual microscattering elements whose dimensions, particularly their height deviation from the basal surface (e.g., the active surface 24' of the main optical element 24 without microstructures), are in the micrometer range (approximately <500 μm, preferably <300 μm, particularly preferably <100 μm, especially 10 to 50 μm). The surface dimensions of the microscattering elements in terms of width and length may also be outside the micrometer range, for example, in the range of 0.1 to 1.0 mm, preferably 0.1 to 0.5 mm. Preferably, the microscattering elements are arranged side-by-side on at least a portion of the active surface 24' of the main optical element 24.

[0066] When the main optical element 24 is in the form of a transparent additional optical element made of solid material, it is preferable that the micro-scattering element formed on the light-emitting surface of the additional optical element is designed to refract the light 22 passing through it in a desired manner, particularly in a desired direction. When the main optical element 24 is in the form of a reflector, it is preferable that the micro-scattering element formed on the reflecting surface of the reflector is designed to reflect the light 22 incident upon it in a desired manner, particularly in a desired direction.

[0067] The micro-scattering elements have specially formed and precisely defined dimensions and shapes to redirect light 26 focused by the main optical element 24 by means of the action surface 24' or scattering elements disposed thereon to one or more desired directions, particularly to desired sub-regions 50 of the intermediate image plane 30. Each region of the main optical element 24 has multiple micro-scattering elements, such that at least 80% of the sub-regions 50 of the intermediate image plane 30 are illuminated not through each individual micro-scattering element, but through each individual region of the main optical element 24, wherein in each region of the main optical element 24, multiple micro-scattering elements work together to achieve the desired illumination of the intermediate image plane 30.

[0068] According to another alternative embodiment of the invention, the main optical element 24 has a plurality of facets on the optically active surface 24', wherein each facet of the main optical element 24 illuminates a plurality of sub-regions 50 of the intermediate image plane 30, preferably illuminating 80% of all sub-regions 50. When the main optical element 24 is in the form of a transparent supplementary optical element made of a solid material, the facets formed on the light-emitting surface of the supplementary optical element are preferably designed to refract light passing through it in a desired manner, particularly in a desired direction. When the main optical element 24 is in the form of a reflector, the facets formed on the reflecting surface of the reflector are preferably designed to reflect light incident upon it in a desired manner, particularly in a desired direction.

[0069] The facets have specially formed and precisely defined dimensions and shapes to redirect light focused by the main optical element 24 by means of the action surface 24' or facets arranged on the action surface to one or more desired directions, particularly to desired sub-regions 50 of the intermediate image plane 30. Each region of the main optical element 24 is formed by a facet, such that at least 80% of all sub-regions 50 of the intermediate image plane 30 are illuminated by each individual facet of the main optical element 24, wherein the desired illumination of the intermediate image plane 50 is achieved by individual facets.

Claims

1. A motor vehicle headlamp (2) for use in a motor vehicle for illuminating an area in front of the motor vehicle with a predetermined light distribution, the headlamp (2) comprising: - a light source (20) for emitting light (22), - a primary optical element (24) for focusing the emitted light (22) in an intermediate image plane (30) of the headlamp (2), and - a secondary optical element (28) for imaging light (52) from the intermediate image plane in a front region in front of the motor vehicle and for generating a predetermined light distribution, characterized in that - the intermediate image plane (30) is divided into a plurality of subregions (50) illuminated by light (26) of the primary optical element (24), and - the primary optical element (24) is designed such that light (52) from each subregion (50) of the intermediate image plane (30) illuminates at least 80% of an active surface (54) of the secondary optical element (28), the primary optical element (24) having a microstructure or a microfacet treatment on an optically active surface (24'), wherein different regions of the primary optical element (24) each have a plurality of microstructured elements or microfacets, and each region of the primary optical element (24) illuminates a plurality of subregions (50) of the intermediate image plane (30).

2. Motor vehicle headlamp (2) according to Claim 1, characterized in that - the subregions (50) of the intermediate image plane (30) each comprise at least one point of the intermediate image plane (30).

3. Motor vehicle headlamp (2) according to Claim 1, characterized in that - the primary optical element (24) is designed such that light (26) from each subregion (50) of the intermediate image plane (30) completely illuminates the active surface (54) of the secondary optical element (28).

4. Motor vehicle headlamp (2) according to Claim 2, characterized in that - the primary optical element (24) is designed such that light (26) from each subregion (50) of the intermediate image plane (30) completely illuminates the active surface (54) of the secondary optical element (28).

5. Motor vehicle headlamp (2) according to any one of Claims 1 to 4, characterized in that - the primary optical element (24) comprises a reflector.

6. Motor vehicle headlamp (2) according to any one of Claims 1 to 4, characterized in that - the secondary optical element (28) comprises a projection lens.

7. Motor vehicle headlamp (2) according to any one of Claims 1 to 4, characterized in that - the light source (20) comprises at least one semiconductor light source, in particular a laser semiconductor light source.

8. Motor vehicle headlamp (2) according to any one of Claims 1 to 4, characterized in that - the primary optical element (24) is designed such that light (26) focused by the primary optical element (24) has a beam (26, 52) that intersects between the primary optical element (24) and the intermediate image plane (30).

9. Motor vehicle headlamp (2) according to any one of Claims 1 to 4, characterized in that The optically effective face (24') of the main optical element (24) is divided into a plurality of regions, and the main optical element (24) is designed such that each subregion (50) of the intermediate image plane (30) is illuminated by as many different regions of the main optical element (24) as possible.

10. Motor vehicle headlamp (2) according to claim 9, characterized in that the main optical element (24) is designed such that each subregion (50) of the intermediate image plane (30) is illuminated by at least 80% of different regions of the main optical element (24).

11. Motor vehicle headlamp (2) according to any one of claims 1 to 4, characterized in that the main optical element (24) has a plurality of facets on the optically effective face (24'), wherein each facet of the main optical element (24) illuminates a plurality of subregions (50) of the intermediate image plane (30).

12. Motor vehicle headlamp (2) according to any one of claims 1 to 4, characterized in that the headlamp (2) has a beam stop (32), in particular a mirror stop (32'), between the main optical element (24) and the secondary optical element (28), wherein the secondary optical element (28) is designed such that at least one edge (34; 34') of the beam stop (32; 32') is imaged in a front region in front of the motor vehicle and thereby produces the predetermined light distribution.

13. Motor vehicle headlamp (2) according to any one of claims 1 to 4, characterized in that the main optical element (24) is designed such that it uniformly illuminates the active face (54) of the secondary optical element (28).

14. Motor vehicle headlamp (2) according to any one of claims 1 to 4, characterized in that the headlamp (2) has a transparent scattering plate (62) arranged in and extending in the intermediate image plane (30).

15. Motor vehicle headlamp (2) according to claim 14, characterized in that an enlargement angle of the scattering plate (62) decreases toward an edge of the scattering plate (62).

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