EP3857273A1

EP3857273A1 - Lighting device for a vehicle

Info

Publication number: EP3857273A1
Application number: EP19782932.8A
Authority: EP
Inventors: Matthias Cumme; Arnaud Deparnay; Roman KLEINDIENST
Original assignee: Carl Zeiss Jena GmbH
Current assignee: Jenoptik AG
Priority date: 2018-09-26
Filing date: 2019-09-25
Publication date: 2021-08-04
Also published as: DE102018123789A1; CN112805599B; WO2020064803A1; US11566765B2; US20220034464A1; CN117968006A; CN112805599A

Abstract

A lighting device is provided, comprising a spatially extended light source with an emitting surface greater than 0.5 mm² and an aspheric TIR lens, which is configured to collimate light from the spatially extended light source, and a refractive diffuser, which is configured to generate a light distribution on the basis of the collimated light.

Description

description

Lighting device for a vehicle

The present application relates to lighting devices for vehicles.

In the field of vehicle lighting technology, lighting devices have to meet numerous complex requirements. These requirements are partly in

Opposites to each other and in many cases require compromises.

For example, there are high requirements with regard to energy efficiency as well as tight specifications in the framework conditions, for example cost pressure,

Service life requirements and space restrictions e.g. due to space requirements of other vehicle components as well as aerodynamic considerations. The

Quality requirements for the lighting distribution provided, described by the so-called lighting function, are continuously increasing and are characterized, for example, in the field of headlights by the desire for lighting functions for wide spectral ranges, for example white light, with complex, high-resolution lighting angles that are defined depending on the solid angle. In many fields of application, asymmetrical lighting functions are particularly required, for example with dipped and cornering lights. Here are achromatic properties of the

Lighting devices are required to avoid, for example, color fringing and over-radiating areas, so-called "hot spots", when illuminating the road, in order to avoid disturbances for vehicle drivers and other road users. An example of such

Faults are blue fringes of color that occur with moving vehicles, for example

Warning signals from emergency vehicles, so-called rotating beacons, could be confused. Corresponding requirements can be found for other vehicle lighting devices, for example taillights, fog lights, daytime running lights, brake lights or

Direction indicators.

In order to meet efficiency requirements, light emitting diodes, LED ("light emitting diodes") are available as light sources. Due to the achievable luminance of LEDs and the need to dissipate the thermal power loss, high-power LEDs also have larger radiation areas with increasing light output. So that is

Beam area in currently available systems, for example, with a luminous flux of 600 lumens 2.1 x 1 mm ² and with a luminous flux of 1200 lumens 4.4 mm ² . Such extensive radiation surfaces emitting in a wide solid angle range are more difficult to collimate with increasing surface, ie the radiation also has a residual divergence that is generally too high after the collimation in order to be able to implement desired lighting functions. If the residual divergence is too great, high-resolution beam shaping is made significantly more difficult.

Efficiency and brightness requirements and the requirement for a long service life therefore conflict with the requirement for minimal residual divergence. On the other hand, for example, the requirement for improved collimation of an extended light source conflicts with the requirement for the limited installation space. Furthermore, the desired achromatic properties require that the beam shaping system be so low

Color defects as possible, which also with space requirements and

Cost claims can collide.

FR 2 919 913 is a light source in combination with a collimator for one

Point light source and a device for beam shaping known, in particular for

Realization of a fog light, taillight or brake light. The collimator is there

for example a TIR (“total internal reflection”) lens, a Fresnel lens or a dome lens that ideally generates parallel beams for an idealized point light source. However, FR 2 919 913 does not disclose anything about the handling of a finally extended light source and the problems of the aforementioned hot spots, such as those caused by the use of holographic diffusers as described in FR 2 919 913, the zeroth or higher diffraction orders have, can occur.

From the prior art are lighting devices, which mirrors for

Use beamforming, known. However, such known arrangements often do not meet requirements in terms of small installation space and low costs.

In order to meet the requirement for achromatic properties at the same time, the collimation and beam shaping system should have as few color errors as possible. That would be e.g. possible if the beam formation and collimation by reflection optics (e.g.

Concave mirror for collimation and segmented mirror system for beam shaping) would be realized. However, such an arrangement could also violate the requirement for space and cost reduction.

The object of the invention is therefore to provide an improved lighting device which at the same time meets the above requirements to a greater extent: For this purpose, a lighting device according to claim 1 is provided. The sub-claims define further embodiments.

The lighting device comprises a spatially extended light source with a luminous area greater than 0.5 mm ² . Furthermore, the lighting device comprises an aspherical TIR lens, which is set up to collimate light from the spatially extended light source, and a refractive diffuser, which is set up to generate a light distribution based on the collimated light.

A TIR (“total internal reflection”) is understood to mean an optical device which transmits at least some of the incident light beams by means of total reflection. TIR lenses are explained in more detail below.

An aspherical lens is understood to mean a lens in which at least one of the refractive surfaces has a surface deviating from a spherical or planar shape.

A refractive diffuser is a component known per se, which has refractive, scattering or diffractive properties on a surface. In the context of this application, refractive diffusers are understood to mean diffusers with smooth surface profile shapes which do not contain any cracks and whose properties are characterized by the

Refraction are dominated. Such diffusers typically have a wave-optically calculated, "smooth" "free-form surface" with a statistical surface profile.

With such a diffuser, the result from any location, e.g. a surface of the diffuser (the location can be specified by coordinates x, y), emitted light waves in their entirety the desired light distribution.

In some examples, the refractive diffuser can comprise a large number of surface areas, each of which contains all the information required for beam shaping. If, for example, a single surface area is illuminated with such refractive diffusers, the desired light distribution is created in the far field. The surface areas can have sizes of 300-1000 pm, for example. All surface areas can be calculated so that they contain stochastically distributed structures. Furthermore, all surface areas can be designed in such a way that they are statistically independent of one another. In addition, all surface areas can be designed in such a way that they can be continuously joined to one another without any visible boundaries being created. In particular, it can be avoided that jump points on the there are joined surface areas, in particular it can be achieved that the refractive diffuser can be continuously differentiated over several surface areas.

The use of surface areas that are statistically independent of one another can have the advantage that inhomogeneities caused by the speckles (sometimes also referred to as light granulation or speckle pattern) occurring on diffusers with partially coherent light can be significantly reduced. In addition, by executing the surface areas as a continuously differentiable surface, the continuously differentiable

can be joined together, have the advantage that scattering centers are avoided, whereby the efficiency and the achievable contrast can be increased.

The calculation of such structures, also referred to as continuous or refractive phase elements, is described, for example, in J. Neauport et al., Applied Optics, Vol. 42, No. 13, pages 2377 ff or in K.-H. Brenner et al, Diffractive optics and microoptics (DOMO) 2000: Conference Edition; OSA Technical Digest, pages 237 ff, ISBN 1-55752-635-4 explained.

By using a refractive diffuser, a large design freedom for the lighting device can be achieved with a relatively small installation space. As a result, a

Installation space can be minimized. In addition, in contrast to diffractive diffusers, a refractive diffuser cannot have a technologically determined zero diffraction order or undesirable higher diffraction orders. This can result in the occurrence of undesirable light effects such as Hot spots and lighting inhomogeneities can be avoided.

An ideal lighting device can be approximated by such a lighting device. Such an ideal lighting device would consist of the following components: a fully collimatable light source, for example a point light source, a collimator, which ensures ideal collimation, and a high-resolution achromatic one

Beam shaping optics with complex, low-scatter beam shaping function. The advantages of the described device, which allow an approach to such an ideal lighting device, are described below.

In some examples, the refractive diffuser is an achromatic refractive diffuser.

Achromatic is understood to mean that the change in the light path, for example due to refraction, is essentially not dependent on the wavelength of the light. This can apply in particular to a range of wavelengths, for example for a specific wavelength range, for example for the visible wavelength range. Achromatic properties of such refractive diffusers are described in M. Cumme and A.

Deparnay, Advanced Optical Technologies, Vol. 4, Issue 1, pages 47-61, 2004. These are based on a combination of diffractive and refractive properties, in which an opposite angular dispersion is used to compensate for chromatic errors. These achromatic properties make it possible to provide an improved light distribution that is free of color fringes, for example blue, for example

Color fringing in white light as described above is.

The refractive diffusers described above potentially have a significantly higher efficiency than all other known diffusers. They can therefore be suitable for fulfilling the desire for increased efficiency in the field of vehicle lighting. This can also make it possible to achieve high brightness or high overall performance.

In some examples, the achromatic refractive diffuser has an optical diffuser surface which is set up to provide the luminous distribution on the basis of the collimated light, the diffuser surface being continuously differentiable.

This can have the advantage that such a continuously differentiable, “smooth” shape of the diffuser surface can significantly reduce or even completely avoid the occurrence of zeroth diffraction orders in the light distribution. Such diffusers also offer a very high efficiency of typically 93% to 97% transmission, even with large ones

Beam angles, for example at a numerical aperture NA up to 0.7, for example at 633 nm. The continuously differentiable shape also prevents phase jumps in the transmitted light. As a result, there are no technological zero diffraction orders and scattering effects. The design freedom when creating the optical diffuser enables almost any, even asymmetrical, far field distributions.

It can thus be possible to provide lighting functions with complex, high-resolution and / or solid angle-defined lighting distribution. Such

Lighting functions can go beyond simple geometric shapes such as circles, ellipses and squares. In some examples, the

Lighting functions have smooth transitions in intensity; in other examples, the lighting functions can have sharp transitions in intensity. A combination is also possible. For example, the intensity can have smooth transitions in a first angular direction, in a second perpendicular to the first angular direction

Angular direction, however, have hard transitions. A hard transition can be understood, for example, to mean a change in the intensity by> 50%, for example by> 75%, for example> 85% in a solid angle range that corresponds to the half-width width solid angle range, FWHM (Full Width Half Maximum) - solid angle range that corresponds to the lighting . A soft transition can be understood, for example, to mean a change in the intensity by <50%, for example <25%, for example <15%, for example <5%, for example <3% in a solid angle range which corresponds to the FWHM solid angle range of the lighting.

The FWHM solid angle range of the lighting is understood to mean the solid angle range that is illuminated by the lighting arrangement described above, consisting of spatially extended LED and TIR lens, and only such

Includes angles of illumination at which the intensity is greater than half the maximum intensity.

In some exemplary embodiments, the refractive diffuser can be designed such that a residual divergence that occurs when it is illuminated, e.g. is created by the system consisting of an extended LED light source and TIR lens, is taken into account in the optical design. This can have the advantage that the deviation of the illumination angle distribution caused by the residual divergence is reduced. This enables the system to be designed in such a way that an ideal lighting device is better approximated. This allows the

Luminous distribution have an improved quality.

In some examples, the diffuser surface has stochastically distributed structures with convex and concave structural components, the structural components having typical lateral dimensions of 15 pm-500 pm.

This can enable inexpensive production with high quality of the light distribution, for example because production using methods suitable for mass production, for example by means of injection molding, is possible. This means that the minimum structure size can already be restricted in the design process, which means that mold tools can be more durable and the mold process can be demolded.This procedure can also be used during the calculation to produce low-resolution optical lithographic processes, e.g. laser beam writing at 1 pm Dissolution, which can also reduce the cost of manufacture. These factors can contribute to a cost reduction with the same or even increased quality of the light distribution. It should be noted that some of the refractive diffusers in optics design offer a choice of profile height and lateral structure size of the element structures while maintaining the generated angular distribution, the profile height and lateral structure size representing coupled quantities that are proportional to one another. This is called scalability of the design. For example, a predetermined illumination angle distribution A could be generated with a diffuser B, in which the average structure depth is, for example, 3 pm and the average lateral structure size is 50 pm. With a scalable design, it is possible to generate the same illumination angle distribution A with a scaled diffuser C in which the average structure depth is, for example, 6 pm and the average lateral structure size is correspondingly 100 pm.

The scalability described above, which can be applied to refractive diffusers, allows a freedom of design that can be used to design as an achromatic refractive diffuser. This can make the compensation more chromatic

Deflection angle errors can be achieved by the combination of light diffraction and light refraction. In each diffuser, light is deflected at all locations on its illuminated surface. Light can be diffracted, e.g. on a blaze grid (cf.

https: //de.wikipedia.orq/w/index.php? title = Blazeqitter & oldid = 175256423, accessed on

16.08.2018), as well as by refraction, e.g. be deflected on the prism. However, the light deflections caused by refraction or diffraction show

opposite changes in the deflection angle as the wavelength changes. Thus, the deflection angle caused by refraction with normal dispersion, e.g. in optical glasses in the visible wavelength range, smaller when the wavelength increases. However, the deflection angle caused by diffraction increases as the wavelength increases. If a prism and a blaze grating were illuminated with a white beam of light and if the orientation of both elements were such that the light would be deflected in the same direction, then a color spectrum would be visible behind both elements, although both color gradients would be oriented mirror-symmetrically to one another.

If you consider a blaze grille as described above as a scalable element and if you were to increase the profile depth and the period piece by piece with a blaze grille, then the grille would initially have a pure diffractive effect. In the case of an extremely long period and a correspondingly increased profile depth, for example if the light beam illuminates only a few or only one period, the diffractive effect would disappear and the optical effect would only be determined by the refractive effect. As a result, there is an intermediate area in which both a refractive effect and a diffractive effect occur. If this range is selected or the period and profile depth are set so that the refractive and diffractive effects are the same, then this is due the opposite dependence of the deflection angle on the wavelength enables a color correction.

This principle can also be used for color correction with refractive diffusers whose structure sizes are scalable. Such diffusers have a structure size in which both diffraction and refraction occur, and the structure size is selected in such a way that the wavelength dependencies of the local deflection angles are compensated for. In particular, achromatic refractive diffusers, as described above, can have an optical design which is based on the considerations described. In contrast to blaze gratings, it is also possible with achromatic refractive diffusers to avoid a technologically determined zero diffraction maximum.

Such achromatic refractive diffusers can therefore have the advantage that color fringes can be avoided when illuminating the roadway.

In some exemplary embodiments, the refractive diffuser comprises at least one region that contains a hybrid structure, the hybrid structure comprising a combination of an achromatic refractive diffuser with a globally acting diffractive structure.

The refractive diffuser can be an achromatic refractive diffuser in whole or in part. In such cases, the hybrid structure can also lie outside the areas of the refractive diffuser in which the refractive diffuser is an achromatic refractive diffuser. Areas of the refractive diffuser can also be achromatic refractive

Diffuser areas that have no hybrid structure.

The at least one region can be part of the refractive diffuser or can include the entire refractive diffuser. It is also possible for there to be a plurality of regions with hybrid structures which can overlap and / or can be spaced apart from one another.

A globally acting diffractive structure is understood here to mean that the structure exerts a diffractive optical function on light which passes through the globally acting diffractive structure, all local areas of the structure deflecting the light in such a way that the deflection occurs in a predetermined relationship all other areas. A given relationship to all other areas means, for example, that all light rays passing through the global structure intersect in one place or in several places, for example located on a circular line. This one or more places can also be one virtual point or several virtual points, as is known, for example, in the case of diffusion lenses.

This can be provided, for example, by a diffractive lens

for example with a Fresnel lens, but also the use of other diffractive structures is possible. Globally acting can mean that the diffractive effect not only locally, but globally, the angular distribution of incoming light, for example on a scale of at least 20%, for example at least 40%, for example at least 60%, for example at least 80%, for example 100% of the Dimension of the globally acting diffractive structure influenced. Such a global effect can be expressed, for example, by focusing parallel light on one point.

Such a globally acting diffractive structure can be set up so that a

Color angle spectrum of the light collimated by the aspherical TIR lens can be reduced. This can be achieved, for example, by optimizing the diffractive structure taking into account the color angle spectrum of the light collimated by the TIR lens, for example by means of optimization calculations as described below. It may also be possible to optimize the TIR lens and the globally acting diffractive structure together. This can further improve the quality of the light distribution.

In contrast to the refractive diffuser structures described above, such a globally acting diffractive structure and / or hybrid structure can include discontinuities. These can be optimized with regard to a central wavelength, for example for a central wavelength A. The central wavelength can be determined by A =! (A _m ax + A _m in), where A _max indicates the maximum wavelength and A _mm the minimum wavelength of the spectral range for which the achromatic correction is aimed for. The globally acting diffractive structure can be designed in such a way that there are jumps for light with the center wavelength l 2tt ^* h, where n = 1 in particular can be selected. However, other essentially integer values for n are also possible. Such discontinuities in the global refractive structure can lead to the occurrence of a zeroth diffraction order, which can be disadvantageous, as already explained above. However, since the jump points of the global refractive structure in the hybrid structure act in combination with an achromatic refractive diffuser, the jump points can each have a different one, for example if they are stochastic, but also in other exemplary embodiments, in combination with the achromatic refractive diffuser have randomly distributed, phase relationship to each other. Thus, all light contributions occurring at the jump points, which could lead to a zero-order diffraction pattern in the light distribution, mutually at least essentially, preferably completely, are compensated for by interference.

A combination of an achromatic refractive diffuser with a globally acting diffractive structure is understood to mean that the two elements are combined. This can be done, for example, by superpositioning profiles of the two structures, for example by superimposing height profiles of the two structures, for example by adding. In other exemplary embodiments, the hybrid structure can be composed of different optical components, which are arranged one behind the other, for example, so that the combination only results from the passing light.

In some exemplary embodiments, the globally acting diffractive structure comprises a Fresnel lens.

It may be possible to design the hybrid structure in such a way that a color correction is carried out by the hybrid structure, for example if color errors arise due to the collimation. This can be done by determining the chromatic properties of the aspherical TIR lens and including them as input parameters in the optical design of the hybrid structure.

In some examples, the spatially extended light source is configured to provide white light as the light.

White light is understood here to mean light that has a combination of different spectral ranges, so that a white color impression is produced for the human eye.

In some examples, the light source includes a light emitting diode and / or a laser diode. The light source may further comprise a phosphor target. This is an inexpensive

Providing a light source of sufficient coherence is possible. It may also be possible to achieve a long service life for the components.

In some examples, the light distribution may have one or more of the following shapes: a symmetrical shape, an asymmetrical shape, a round shape, a square shape, an elliptical shape.

Here, several of the above shapes mean that some shapes can have a combination of the shapes mentioned. For example, an elliptical shape can have symmetrical properties, for example a mirror symmetry along the Major axes. In this respect, the light distribution can also have a combination of the shapes mentioned, for example an elliptical shape in a first area and a round shape in a second area, which can be different from the first area. Other combinations are also possible.

In some examples, the light distribution has one or more of the following

Intensity distributions on: a homogeneous intensity distribution, a top hat-shaped

Intensity distribution, a Gaussian intensity distribution, a super Gaussian

Intensity distribution.

Several of the intensity distributions here means that the intensity distribution

different aspects, for example for certain solid angle ranges, combined. For example, an asymmetrical intensity distribution can be achieved by superimposing a top-hat-shaped intensity distribution with a super Gaussian intensity distribution. As a result, asymmetrical intensity distributions can be provided that the

Road traffic requirements are sufficient and in some examples a tough one

Avoid transition from illuminated to unlit areas.

In addition, the light distribution can be designed in such a way that sharp contours are created in some places. For example, Lettering or certain characters such as Arrows are generated that show a strong contrast when they are projected onto the road.

Likewise, the illuminated areas can be any, mathematically defined

Brightness modulations included, i.e. Changes in brightness across the light distribution.

In some embodiments, the aspherical TIR lens is not rotationally symmetrical.

For example, for a spatially extended light source that has an asymmetrical, for example rectangular, shape, the collimation cannot be performed by a

rotationally symmetrical TIR lens can be improved compared to a rotationally symmetrical TIR lens. This will be explained in more detail later.

In some examples, the coupling-in surfaces, that is to say the surfaces which face the light source, enclose the TIR lens as far as possible around the extended light source and thus ensure that radiation emanating from the light source is in the largest possible solid angle range, for example essentially Half space around the light source into which the TIR lens is coupled. Essentially encompassing a half space around a region is understood to mean that the spatially extended light source occupies a large part of the solid angle range of the half space, for example 80%, for example 85%, for example 90%, for example 95%, for example 100% of the solid angle range of the half space. This can have the advantage that a large part of the light emitted by the spatially extended light source is received and collimated by the TIR lens, which prevents losses and thus improves the efficiency of the system.

In some examples, the spatially extended light source has a shape that includes a first length in a first direction and a second length in a second direction that is different from the first direction. The first length is greater than the second length.

In some examples, the shape of the light source may be a rectangular shape having a first side length and a second side length, the first length being the first side length and the second length being the second side length.

This can have the advantage that industrially available light sources can be used and that the shape can improve other properties of the light source, for example heat dissipation, which can improve the service life and efficiency.

In some examples, the aspherical TIR lens has a first dimension in the first direction and a second dimension in the second direction, the first

Extent is greater than the second extent.

This can have the advantage that the TIR lens shaped in this way has improved optical properties compared to a TIR lens that is not adapted to the shape of the spatially extended light source, i.e. collimation adapted in the first and second directions.

In some examples, the aspherical TIR lens is set up to produce an essentially rotationally symmetrical collimation of the spatially extended light source.

A rotationally symmetrical collimation is understood here to mean that the deviation from an ideal collimation has a rotational symmetry with respect to the optical axis of the TIR lens, for example is constant in the amount of the deviation angle from the ideal collimation. Under an essentially rotationally symmetrical collimation understood accordingly that the deviation is essentially constant, for example less than 20%, for example less than 10, for example less than 5%, in particular less than 1%.

In the idealized case of a point light source, it is possible to achieve perfect collimation with an angular deviation from the optical axis of 0 ° using an aspherical lens.

In the case of an extended light source in a plane perpendicular to the optical axis, this is no longer possible. In any section plane perpendicular to the optical axis, the angular deviation, also referred to as the local divergence angle, to the optical axis is proportional to the extension of the light source in relation to the lens diameter in the section plane perpendicular to the optical axis and to the reciprocal focal length of the lens.

In the case of an asymmetrical light source, the extent of the light source depends on the choice of the section plane perpendicular to the optical axis. So that's local too

Divergence angle depending on the choice of the cutting plane.

Because the TIR lens has a first dimension in the first direction and a second dimension in the second direction, the first dimension being greater than the second dimension, this effect can now be at least partially compensated for.

For example, in the case of an elliptical light source, an elliptical shape of the TIR lens can be selected, so that the angle of divergence is the same again for all cutting planes, because in the cutting planes in which the light source has a larger extension, the TIR lens also has a larger extension .

In the case of an angular light source, for example a rectangular light source, this property can essentially also be achieved. An elliptical shape of the TIR lens can also be selected here in order to take into account the different dimensions of the light source in different directions and to improve the collimation. In order to additionally reduce the influence of such deviations, the focal length of the TIR lens can be increased, whereby an optimization process can be carried out together with other opposing requirements, for example construction volume.

The elliptical shape of the TIR lens is only one example of non-rotationally symmetrical shapes of the TIR lens.

In some exemplary embodiments, another non-rotationally symmetrical shape of the aspherical TIR lens can also be selected. Here, the non-rotationally symmetrical Shape of the TIR lens can be selected depending on the shape of the spatially extended light source.

In some embodiments, a shape of the aspherical TIR lens can be based on a shape of the spatially extended light source.

For example, for an elliptical shape or a rectangular shape, the spatial

extended light source, a TIR lens has an elliptical shape in the section plane perpendicular to the optical axis.

The above-mentioned procedures can have the advantage that improved collimation can be achieved in the same installation space.

This can have the advantage that the extended shape of the TIR lens can reduce the influence of the asymmetry of an asymmetrical, spatially extended light source on the collimation.

In some examples, the aspherical TIR lens includes an axis, a first surface, a second surface, an exit surface, and a reflector surface, wherein

the axis runs through the spatially extended light source,

the exit surface is planar and perpendicular to the axis, the

Exit surface that provides collimated light

the first surface has a bi-aspherical shape and intersects the axis, the second surface has a free shape and does not intersect the axis and

wherein the reflector surface has a parabolic shape.

In the examples in which the TIR lens has a first dimension that is greater than a second dimension, the shapes can be defined in a sectional plane that runs through the axis, for example in a cross-sectional plane of the TIR lens. In other sectional planes, the shapes can also be deformed in these planes in accordance with the deformation of the TIR lens with respect to the cross-sectional plane, as is known in the field of computer-aided design (CAD), for example from loft features.

In some examples the shapes are centered shapes, in other examples decentered shapes, for example the first surface can be a decentered bi-aspherical shape. Here, the bi-aspherical shape can be different for different cutting planes through the TIR lens that run through the axis. In some exemplary embodiments, TIR lenses with first and second surfaces, as described above, are combined with hybrid structures, as previously described in connection with exemplary embodiments of the refractive diffusers. In these exemplary embodiments, the at least one region can fill at least part of a projection of the first surface and / or the second surface onto the refractive diffuser. The projection can take place along the axis. However, the projection can also be carried out by means of ray tracing of the light, whereby a projection onto a part of the refractive diffuser can be determined by tracking a light bundle emanating from the light source and determining the area in which cross the light beam through the refractive diffuser, the area determined in this way then being able to be determined as the at least one region.

In some examples, the aspherical TIR lens includes a bump region between the first and second surfaces, the bump region having a surface shape that is one

Manufacturing radius is not less and is designed such that a light component is deflected from the spatially extended light source that passes through the impact region so that the corresponding light component does not fall within a solid angle range behind the TIR lens, so that the overall light distribution behind that of the diffuser is essential being affected.

Including that the light portion deflected from the impact region affects the light distribution in the

Essentially not influenced, it is understood that the light component does not essentially influence a luminous distribution that is generated without light that passes through the impact region. This can mean that the solid angle-dependent intensity of the light distribution behind the diffuser for no solid angle due to the proportion of light that passes through the impact region, for example by more than 20%, for example 15%, for example 10%, for example 5%, for example 1%, based on the the desired solid angle dependent intensity behind the diffuser is changed.

The aforementioned criteria and targets can be obtained from a specialist at

Creation of the optical design are taken into account, for example, by this

Targets as optimization goals for numerical optimization processes for optical

Design software based on ray tracing is specified, for example as a "merit function" in the optical design software Zemax OpticStudio.

A production radius is understood to mean the smallest possible curvature that can still be produced using a production method, for example based on

Tool sizes or due to material properties. This can have the advantage that a cost optimization of the manufacturing costs is achieved in that a suitable manufacturing radius is already taken into account in the design phase. In particular, the influence of light from the impact region on the luminous distribution is to be minimized or the impact region is to be designed in such a way that the light emanating therefrom is specifically converted into the useful distribution. In this way, it can be avoided that light which passes through the impact region leads to the formation of hot spots in the light distribution, which could be the case, for example, due to a reflection at the impact region and subsequent reflection in the TIR lens. In some examples, the luminous distribution can be prevented from having an undesirable distance dependency due to non-collimated light from the impact region.

In some exemplary embodiments, the proportion of light which passes through the impact region and is directed in the direction of the exit surface is over 95%.

The light component can also make up other components, for example in the range between 70% and 100%. In this case, a higher proportion is desirable in many cases, although lower values can also be useful as part of an optimization process.

for example, to allow larger production radii and thus cheaper production, as long as the resulting light distribution meets the requirements.

Because the butt region is included in the optical design, it is possible that the manufacture of such a lighting device can be possible using inexpensive methods. Some cheap manufacturing processes, such as injection molding, are characterized in that certain manufacturing radii cannot be undercut, since the removal of radii that are too small can lead to unpredictable effects in relation to the deflection of light. This is not limited to injection molding, but also applies to numerous other manufacturing processes.

In some exemplary embodiments, the free form of the second surface is defined using Q polynomials.

Q polynomials are, for example, from I. Kaya et al., Comparative assessment of freeform polynomials as optical surface descriptions, OPTICS EXPRESS 22683, Vol. 20, No. September 20, 24, 2012. The free form definition using Q polynomials has the advantage that numerical optimization of the free form and / or other forms becomes more robust and easier. In some embodiments, the Q polynomials can be decentered Q polynomials. In order to decenter the Q polynomials, offset values corresponding to the required decentration, ie lateral displacement, must be provided for the location coordinates. As a result, the surfaces described by Q polynomials are shifted relative to the optical axis, which results in additional degrees of freedom for the optical design.

In some embodiments, the aspherical TIR lens and the refractive diffuser can be integrally formed as one component. In some cases

Embodiments of the refractive diffuser can be formed in one piece with the exit surface of the aspherical TIR lens.

This can have the advantage that the manufacturing costs can be reduced. At the same time, due to the one-piece production, an exact and reproducible fit between the TIR lens and the refractive diffuser can be achieved. This can

Arrangement errors of these components to one another can be avoided and it may be possible to dispense with an adjustment of components.

This can have the advantage that production is particularly simple and therefore particularly cost-effective.

In some exemplary embodiments, the aspherical TIR lens and / or the refractive diffuser can be produced by means of an injection molding process.

In some exemplary embodiments, the lighting device can be designed as a lighting device for a vehicle. Here, the lighting device can, for example, as a

Headlights, a high beam, a fog light, a low beam, a rear light or be designed as a daytime running light. Use as other lighting equipment is also possible. The lighting device can be used particularly advantageously when the achromatic properties are advantageous. This is for example at

Luminous devices, which are intended to provide broad spectral ranges of light, for example in the case of white light. However, other constellations are also conceivable, for example a lighting device for a combined brake light and direction indicator, the brake light in the red spectral range and the turn signal in the yellow spectral range emitting light, which can also be advantageously implemented by a lighting device according to the invention.

For better understanding, exemplary embodiments are explained in more detail below with reference to the accompanying drawings. Show it: 1 is a lighting device according to an embodiment,

Fig. 2 shows a spatially extended light source with a luminous area according to one

Embodiment,

3A and 3B show a TIR lens in accordance with an exemplary embodiment, in this case FIG. 3A shows a cross-sectional view and FIG. 3B shows a frontal view of the TIR lens with each

corresponding markings of the sub-areas of the TIR lens,

4 shows a refractive diffuser according to an exemplary embodiment,

5A and 5B show a light distribution according to an exemplary embodiment,

Fig. 6 shows an embodiment of an achromatic refractive diffuser with a

Hybrid structure.

Various exemplary embodiments are now explained in detail below. This detailed description is not to be interpreted as restrictive. One is in particular

Description of an exemplary embodiment with a large number of features, components or details should not be interpreted to mean that all of these features, components and details are necessary for implementation. Variations and modifications which have been described for one of the exemplary embodiments can also be applied to other exemplary embodiments, unless stated otherwise. Characteristics of different

Embodiments can also be combined with each other to create further

To form embodiments.

Fig. 1 shows a lighting device according to an embodiment. The light from a spatially extended light source 110 is collimated by an aspherical TIR (total internal reflection) lens 120 and transformed by a refractive diffuser 130 in order to produce a luminous distribution 140 based on the collimated light. In some exemplary embodiments, a protective layer 150, for example made of glass, may also be present, which protects the structure 110, 120, 130 from environmental influences. In other exemplary embodiments, the protective layer 150 can be embodied in one piece with the refractive diffuser 130. The spatially extended light source 110 has a luminous area greater than 0.5 mm ² . In some exemplary embodiments, the spatially extended light source 110 is realized as a light-emitting diode, LED (“light emitting diode”) or groups of LEDs. This is explained in more detail below in connection with FIG. 2. in the

1, the refractive diffuser 130 is a divergence-adapted achromatic refractive diffuser. The light distribution 140 shown in FIG. 1 is a defined asymmetrical, high-resolution white light distribution.

2 shows a spatially extended light source with a luminous area according to one

Embodiment. FIG. 2 shows a spatially extended light source 200, which comprises a first LED 210 and a second LED 220. The spatially extended light source 200 can be described by a first direction R1 and in a second direction R2, the spatially extended light source being extended in the first direction R1 and second direction R2. The spatially extended light source 200 has a first length L1 in the first direction R1 and a second length L2 in the second direction R2. In the example shown in FIG. 2, the first length L1 is greater than the second length L2, so that a rectangular shape of the light source 200 results in the example of FIG. 2. As previously described, a

The challenge is to collimate such an extensive light source. Such collimation can be achieved in an efficient form by means of the TIR lenses described below in connection with FIGS. 3A and 3B.

3A and 3B show a TIR lens 300, 301 according to an exemplary embodiment, with FIG. 3A showing a cross-sectional view 300 of the TIR lens and FIG. 3B showing a frontal view 301 of the TIR lens. The TIR lens 300, 301 is set up to collimate light from the

To provide light source 302. In the example shown, the light source 302 is an LED, which can correspond to the light source 200 in FIG. 2. However, other light sources 302 are also possible. In the example shown, the light source 302 has a rectangular shape with different first lengths L1 and second lengths L2, wherein the first length L1 can run in a first direction R1 and the second length L2 can run in a second direction L2. The lengths and directions can correspond to the lengths and directions of FIG. 2.

In order to improve the quality of the collimation of the spatially extended luminous area, the TIR lens 300, 301 is asymmetrically shaped. In the exemplary embodiment shown, the TIR lens is elliptically shaped and has a first dimension D1 in the first direction R1 and a second dimension D2 in the second direction R2 around the center point M. Here, the first dimension D1 is larger than the second dimension D2.

Due to the asymmetrical shape of the TIR lens 300, 301, it may be possible that the structure meets the requirements for the lighting device 100 and provides an angular distribution in the angular region behind the collimator, which has a residual divergence that is as small as possible and as uniform as possible in all directions . 3A shows two different beam entry areas for the light of the spatially extended light source 302, namely a first area 306 and a second area 307, as well as an exit area 310 and a reflector area 308. The axis 350 running through the center point M runs through the spatially extended light source 302. In the exemplary embodiment shown, the exit surface 310 is planar and extends perpendicular to the axis 350, the exit surface 310 providing the collimated light. The first surface 306 and the second surface 307 are formed independently of one another. in the

In the exemplary embodiment, the first surface 306 has a bi-aspherical shape and intersects the axis 350. The second surface 307, however, has a free form and does not intersect the axis 350. The cross-sectional view 300 of the reflector surface 308 has a paraboloid shape. The planar shape of the exit surface 310 has the advantage that in some examples this surface can be formed in one piece with the refractive diffuser. This can enable a collimation diffuser module to be manufactured in a single injection molding process. The two surfaces 306, 307 enclose a half space around the spatially extended light source and thus ensure that a large part of the radiation is coupled into the transparent material of the TIR lens. This will also

Radiation components recorded in angular ranges far from the axis, which increases the efficiency of the device.

The TIR lens is shaped in such a way that the surfaces are as perpendicular as possible to the incident partial beam of the light source. In this way, it can be achieved that relatively small deflection angles are produced at the interfaces due to refraction when coupling into the material of the TIR lens, which results in a reduction in the chromatic aberration due to the material-dependent dispersion, as well as a high coupling efficiency into the material of the TIR Lens results. 3A clearly shows that the first surface 306 and the second surface 307 are one

Have butt region 309 between the first surface 306 and the second surface 307. As indicated schematically in FIG. 3A, the impact region 309 has a surface shape that does not fall below a manufacturing radius and is designed in such a way that a proportion of light from the spatially extended light source 302 that passes through the impact region 309 is as high as possible in the direction of FIG Exit surface 310 is directed and in particular is not directed to the reflector surface 308. This has the advantage that areas of high intensity (previously mentioned hot spots) in the resulting light distribution, which could otherwise occur if the impact region 309 is not carefully optimized, and in the light distribution (see light distribution 140 of FIG. 1) can be avoided ) would have a negative impact. This could be the case in particular in the case of an uncontrollable production of the joint, that is to say when production radii are required which are below the possible production radii. Here, the light coming from the light source 302 can be different Beams are described. The beam 304 emerges from the lower angular range of the total beam and has an oval shape in the front view of FIG. 3B, which corresponds to the surface 306 in FIG. 3B. The beam 305 passes through the impact region 309. The beam 303 results from the higher angular range of the total beam and passes through the second surface 307 and has an oval-annular shape which corresponds to the reflector surface 308 in the front view of FIG. 3B. A low chromatic aberration is realized by the design shown, since the shape ensures that the beam 303 is deflected mainly by reflection on the surface 308, the reflections being free of achromatic aberrations. The collimator shown in FIGS. 3A and 3B thus enables spectrally homogeneous collimation with minimized chromatic aberration, high efficiency of light transmission with low residual divergence of less than 6 ° and at the same time a compact design. In addition, the component can be produced monolithically using the injection molding process, it being possible to also produce a refractive diffuser structure, for example an achromatic refractive diffuser structure, in one piece using the injection molding process. The diffuser structure is explained below in connection with FIG. 4.

4 shows a refractive diffuser 400, which is designed as an achromatic refractive diffuser. On the left side of FIG. 4, a height contour 421 of the refractive diffuser as a function of the location along the path 410 is shown in the diagram 420. The height contour describes a topography function for path 410. As can be seen from the height contour 421, the height profile changes continuously differentiable by an average value 440, the standard deviation of the height contour 421 added with the mean value of the height contour 422 and the standard deviation subtracted from the mean value of the height contour 423 being shown as a reference. Here, the height contour 421 runs through local maxima 430 and minima 431. The fact that the height contour 421 is continuously differentiable makes it possible

Avoid phase jumps in the wavefront of the transmitted light. In this way, technologically caused zero diffraction orders are avoided and very good transmission properties, as described above, can be achieved. The already described scalability of the diffuser offers further degrees of design freedom for the

Luminous distribution in the far field and in particular possibilities of an achromatic

Generate light distribution. This is described below in connection with FIGS. 5A and 5B.

5A and 5B show a light distribution according to an exemplary embodiment.

5A shows a possible light distribution 500 of the lighting device. Such a light distribution 500 can be generated, for example, by the lighting device in FIG. 1 will. In the example in FIG. 5A, an asymmetrical form of the light distribution is achieved. The possible combination of the spatially extended light source with the aspherical TIR lens and the refractive diffuser results in numerous

Design options and degrees of design freedom for the light distribution 500, as described above and below. In order to clarify the asymmetrical light distribution 500 achieved, various intensity profiles 511, 521, 531 for cuts 510, 520, 530 in FIG. 5B are plotted as a function of the radiation angle.

FIG. 5B shows the intensity of the white light for the cuts of FIG. 5A in arbitrary units as a function of the radiation angle in arbitrary units. Curve 51 1 shows the intensity profile of section 510, curve 521 the intensity profile of section 520 and curve 531 the intensity profile of section 530. As can be seen from the curves, various symmetrical and asymmetrical light distributions can be seen in FIG

different areas of the light distribution 500 can be achieved. Thus, curve 531 has an almost symmetrical super-Gaussian shape, whereas curve 521 has an almost symmetrical top-hat-shaped super-Gaussian distribution. Curve 51 1, on the other hand, is highly asymmetrical and represents a superposition of two modified super-Gaussian intensity distributions. These intensity distributions can be determined by optimizing the various components with large degrees of design freedom.

In particular, very soft intensity transitions, such as the example of the

Intensity curve shown in curve 531 can be achieved, but also sharper transitions, such as, for example, in the intensity curve of curve 521, are possible.

6 shows an embodiment of a refractive diffuser with a hybrid structure.

In some exemplary embodiments, at least part of the refractive diffuser can have a hybrid structure, as explained at the beginning. Such hybrid structures can have the advantage that chromatic errors of the TIR lens can be compensated for.

In the exemplary embodiment in FIG. 6, a height contour of an achromatic refractive diffuser 610 is shown as an example as a function of the location along a path. As previously explained, the diffuser can also be a refractive diffuser in other exemplary embodiments. The achromatic refractive diffuser shown can, for example, correspond to the achromatic refractive diffuser 400 of FIG. 4. The height profile of the achromatic refractive diffuser is now used as the starting point for a diffuser with a hybrid structure

to provide. For this purpose, a height profile of a globally acting diffractive structure 620 is overlaid with the height profile of the achromatic refractive diffuser 610. 6 this is carried out by way of example for a profile, the height profiles 610, 620 being added are superimposed. A hybrid structure is obtained by superimposing the height profiles of the achromatic refractive diffuser and the globally acting diffractive structure. A height contour of the hybrid structure 630 is also shown in FIG. 6 as an example.

In the example shown, the globally acting diffractive structure is restricted to region A. Region B, on the other hand, has no globally active diffractive structure. In the example shown, the globally acting diffractive structure in region A is designed as a Fresnel lens 621, which is designed to make 2u phase jumps of light for a wavelength l

bring about.

In other exemplary embodiments, region A can extend over other regions, also fill the entire region, so that region B is omitted, or there can be several different regions such as A and B. In particular, the structures can be designed at different locations for different center wavelengths. This can be advantageous, for example, if it is known that there is a different spectral light distribution in certain regions than in other areas. This can be the case, for example, due to chromatic aberration in optical components, for example in the TIR lens.

The hybrid structure in region B is unchanged from the original height profile of the achromatic refractive diffuser. The hybrid structure in region B can have the advantage that a color angle spectrum of the light collimated by the aspherical TIR lens can be reduced.

The diffuser with a hybrid structure can, for example, be arranged on the exit surface 310 of FIGS. 3a and 3b, and the region A can be selected such that the beam 304 passes through the region A. Then the hybrid structure can at least partially compensate for a chromatic error, which can arise, for example, due to refraction on surface 306. This can further improve the quality of the light distribution. At the same time, the hybrid structure, as described above, prevents the formation of zeroth diffraction orders in the light distribution.

Thus, different types of can be used with refractive diffusers and TIR reflectors

Lighting devices for vehicles, in particular headlights, but also

Direction indicators, reversing lights, fog lights, brake lights and the like can be provided with the desired light distributions, which allows great design freedom.

Claims

1. Lighting device (100) comprising:

a spatially extended light source (110, 200, 302) with a luminous area (230) larger than 0.5 mm ² ,

an aspherical TIR lens (120, 300, 301) configured to collimate light from the spatially extended light source (110, 200, 302) and

a refractive diffuser (130, 400), which is set up to generate a light distribution (140, 500) based on the collimated light.

2. Lighting device (100) according to claim 1, wherein the refractive diffuser (130, 400) is an achromatic refractive diffuser (400).

3. Luminous device (100) according to claim 1 or 2, wherein the refractive diffuser (130, 400) is set up to receive the collimated light with a residual divergence, the refractive diffuser for generating the luminous distribution (140, 500) based on the collimated Light is set up with the residual divergence.

4. Lighting device (100) according to one of the preceding claims, wherein the achromatic refractive diffuser (400) has an optical diffuser surface (400) which is set up to provide the light distribution (140, 500) on the basis of the collimated light, the diffuser surface ( 400) is continuously differentiable.

5. The lighting device (100) according to claim 4, wherein the diffuser surface (400) has stochastically distributed structures (430, 431) with convex (430) and concave (431) structural components, the structural components having lateral dimensions of 15 pm-500 pm.

6. Lighting device (100) according to one of the preceding claims, wherein the

Luminous distribution (140, 500) has one or more of the following shapes:

a symmetrical shape, an asymmetrical shape, a round shape, a square shape, an elliptical shape.

7. Lighting device (100) according to one of the preceding claims, wherein the light distribution (140, 500) has one or more of the following intensity distributions:

a homogeneous intensity distribution, a top-hat-shaped intensity distribution, a Gaussian intensity distribution, a super-Gaussian intensity distribution.

8. Lighting device (100) according to one of the preceding claims, wherein the aspherical TIR lens (120, 300, 301) is not rotationally symmetrical and wherein the aspherical TIR lens (120, 300, 301) is in a solid angle range, starting from one

The center (M) of the spatially extended light source (110, 200, 302) is located, the solid angle region essentially comprising the half space around the spatially extended light source (110, 200, 302).

9. lighting device (100) according to any one of the preceding claims, wherein the spatial

extended light source (1 10, 200, 302) a shape comprising a first length (L1) in a first direction (R1) and a second length (L2) in a second direction (R2) which is different from the first direction (R1 ), the first length (L1) being greater than the second length (L2).

10. Lighting device (100) according to claim 9, wherein the aspherical TIR lens (120, 300,

301) a first extension (D1) in the first direction (R1) and a second

Extension (D2) in the second direction (R2), the first extension (D1) being greater than the second extension (D2).

1 1. lighting device (100) according to one of claims 9 or 10, wherein the aspherical TIR lens (120, 300, 301) is set up to generate a substantially rotationally symmetrical collimation of the spatially extended light source (110, 200, 302).

12. Lighting device (100) according to one of the preceding claims, wherein the aspherical TIR lens (120, 300, 301) an axis (350), a first surface (306), a second surface (307), an exit surface (310) and a reflector surface (308), wherein:

the axis (350) runs through the spatially extended light source (110, 200, 302), the exit surface (310) is planar and perpendicular to the axis (350), the exit surface (310) providing the collimated light,

the first surface (306) has a bi-aspherical shape and intersects the axis (350), the second surface (307) has a free form and does not intersect the axis (350) and wherein the reflector surface (308) has a paraboloid shape.

13. The lighting device (100) according to claim 12, wherein the aspherical TIR lens (120, 300, 301) comprises a collision region (309) between the first (306) and the second (307) surface, the collision region (309) one Has surface shape that a

Manufacturing radius is not less and is designed such that a light component is deflected by the spatially extended light source (110, 200, 302) that passes through the impact region so that the light component does not essentially influence the light distribution.

14. The lighting device (100) according to claim 13, wherein the light portion is directed to a portion of at least 70% in the direction of the exit surface (310) and not to

Reflector surface (308) is steered.

15. Lighting device (100) according to claim 14, wherein the proportion is over 95%.

16. Lighting device (100) according to any one of claims 12-15, wherein the free form of the second surface (307) is defined by means of Q polynomials.

17. Lighting device according to one of the preceding claims, wherein the refractive diffuser comprises at least one region which contains a hybrid structure (630), wherein the

Hybrid structure (600) comprises a combination of an achromatic refractive diffuser (400, 610) with a globally acting diffractive structure (620).

18. Lighting device according to claim 17, wherein the globally acting diffractive structure (620) comprises a Fresnel lens (621).

19. Lighting device according to claim 12 and 17 or 12 and 18, wherein the at least one region fills at least part of a projection of the first surface (306) and / or the second surface (307) onto the refractive diffuser (130, 400).

20. Lighting device (100) according to one of the preceding claims, wherein the aspherical TIR lens (120, 300, 301) and the refractive diffuser (130, 400) are integrally formed as a component.

21. The lighting device (100) according to claim 20, wherein the refractive diffuser (130, 400) is formed in one piece with the exit surface (310) of the aspherical TIR lens (120, 300, 301).

22. Lighting device (100) according to one of the preceding claims, wherein the aspherical

TIR lens (120, 300, 301) and / or the refractive diffuser (130, 400) are produced by means of an injection molding process.

23. Lighting device (100) according to one of the preceding claims, wherein the

Lighting device (100) is designed as a lighting device for a vehicle.