Lighting device and motor vehicle lamp

Abstract

The invention relates to a lighting device (1), wherein the lighting device (1) comprises a light source (2) for generating an illumination light (7), and a hologram arrangement (4) which can be illuminated by the illumination light (7). The hologram arrangement (4) is designed to separate the illumination light (7) into a first portion (7.1) for generating a holographic image (12) and a second portion (7.2) for generating a lighting function (13).

Description

[0001] LIGHTING DEVICE AND MOTOR VEHICLE LIGHT

[0002] The present disclosure relates to a lighting device, e.g. for a motor vehicle, and / or a motor vehicle lamp.

[0003] Motor vehicles have various types of lighting devices, e.g., interior lighting, displays and / or exterior lighting devices, whereby the exterior lighting devices usually serve to ensure driving safety, e.g., to illuminate a road ahead in the dark, to ensure visibility for other road users in the dark, and / or to warn or inform other road users (e.g., direction indicators and / or brake lights).

[0004] In addition to these functions, lighting devices are also known that are additionally provided with a characteristic luminous signature. These lighting devices are designed in such a way that the light emitted by the respective lighting device creates a characteristic shape, e.g., company- or manufacturer-specific. This shape can, for example, be three-dimensional.

[0005] One possibility for implementing luminous signatures is the use of holograms, which create holographic images from which the light of the lighting device appears to emanate. This makes it possible to create lighting functions for motor vehicles, such as taillights or brake lights, that appear to originate outside the vehicle and / or to implement characteristic luminous signatures.

[0006] Such illumination devices typically comprise the hologram, which generates the desired luminous signature, and a light source to illuminate the hologram. To achieve an appropriate quality of the luminous signature, the reconstruction of the holograms used must exhibit certain parameters, e.g., a narrow angular and spectral distribution, as well as a small deviation from the design parameters. This places high demands on the light-shaping optics that generate such a reconstruction light wave. The combination of at least one light-emitting diode as a light source results in a relatively high light loss, since only a small portion of the original light is used for reconstruction.

[0007] Against the background of this prior art, the object of the present disclosure is to provide a device which is each suitable for enriching the prior art.

[0008] The problem is solved by the features of the independent claims. The subclaims each contain optional developments of the disclosure.

[0009] The task is then solved by a lighting device, e.g. for a motor vehicle.

[0010] The lighting device comprises a light source for generating an illuminating light.

[0011] The lighting device comprises a hologram array that can be illuminated by the illumination light. In other words, the hologram array can be arranged such that it can be illuminated by the illumination light and / or the illumination light falls onto the hologram array.

[0012] The hologram arrangement is designed to separate the illumination light into a first portion for generating a holographic image (and / or a luminous signature) and a second portion for generating an (optionally non-holographic) luminous function (and / or to output it in different directions).

[0013] The hologram arrangement may comprise at least one (volume) hologram. The at least one hologram may also be referred to as at least one holographic grating.

[0014] A hologram or volume hologram can be understood as a (phase) grating, i.e. a light-sensitive volume material in which a refractive index or refractive indices have been specifically changed locally (e.g. by holographic exposure). This structure leads to local phase changes of an incoming light wave and thus causes the incoming light wave to be diffracted or redirected in a specific direction. By illuminating a hologram with light, the image information contained in the hologram can be reproduced. Such illumination can also be referred to as reconstruction. A holographic function of a hologram determines how the hologram modifies incident light, for example to reproduce image information.

[0015] In general, any optical function can be realized using a hologram. The degree of freedom in optical design is significantly higher with a hologram than with conventional solutions, e.g., using lenses, mirrors, and the like.

[0016] A hologram can generally be wavelength- and / or angle-selective. This selectivity can be specifically adjusted through the design of the hologram, e.g., via the thickness of the hologram and the angle at which the exposure occurs to reproduce the image information contained in the hologram during the production of the hologram. These properties can be used to design the emission characteristics of a light source, e.g., at least one light-emitting diode. Wavelength selectivity and / or angle selectivity allows beam shaping and color filtering to be combined in one hologram. Transmission and / or reflection holograms (or transmission and / or reflection gratings), for example, can be used for this type of beam shaping and / or filtering function.

[0017] The lighting device described above offers a number of advantages. Among other things, it enables improved and more effective use of the light generated by the light source. For example, a portion of the light that would normally be lost unused can be used for other purposes, such as additional lighting effects and / or lights. Thus, the illumination light can advantageously be divided into at least two portions, which can, for example, be optimized such that as little light as possible from the first portion is lost unused without contributing to the generation of the holographic image. Instead, this light can be assigned to the second portion during the division, thereby creating the lighting function.

[0018] The use of the hologram arrangement to split the illumination light also advantageously enables a more compact arrangement than a solution using, for example, mirrors and / or lenses.

[0019] Possible further developments of the lighting device described above are explained in detail below.

[0020] The lighting device may comprise a (e.g., non-holographic) optical element that may be configured to generate the lighting function, e.g., additional illumination, in response to illumination of the optical element by means of the second portion. The optical element may be configured to generate the lighting function by means of the second portion that illuminates the optical element and / or is incident on the optical element, e.g., by deflecting (at least a portion) of the second portion. The hologram arrangement may comprise a primary hologram. The primary hologram may be configured to generate (and / or reconstruct) a holographic image (or a light signature) by means of the first portion of the illumination light, e.g., by deflecting and / or reflecting the first portion.

[0021] The primary hologram can be illuminated by the illumination light. In other words, the primary hologram can be arranged such that it is illuminated by the illumination light and / or the illumination light falls on the primary hologram. The primary hologram can be configured to separate the illumination light into the first portion and the second portion. The primary hologram can be configured to output the second portion toward the optical element.

[0022] The light source and the primary hologram can be arranged relative to one another such that the illumination light falls at a (predetermined) angle or angular range, e.g., directly, onto the primary hologram. Alternatively, the lighting device can have at least one further optical element or hologram element for deflecting and / or reflecting the illumination light (toward the primary hologram). The further optical element or hologram element can be designed and / or arranged such that the illumination light falls onto the primary hologram at the angle or angular range. The angle or angular range can be selected such that the primary hologram generates the holographic image in response to being illuminated by the illumination light, and / or can correspond to an angle or angular range for which the primary hologram is designed to generate the holographic image.

[0023] An image can be recorded in the primary hologram, which defines the holographic image or light signature and redirects and / or reflects the first portion (at least partially) into or on the primary hologram to generate the holographic image. The first holographic image can be generated or created outside the lighting device, e.g., freely suspended.

[0024] The primary hologram can be designed such that the second portion passes through the primary hologram without deflection. The primary hologram can be transparent to the second portion. The second portion can comprise the zero-order illumination light (or light rays of the illumination light) or consist of the zero-order illumination light.

[0025] The primary hologram can be arranged between the light source and the optical element.

[0026] The primary hologram can be illuminated with the illumination light on a first side of the primary hologram. The optical element can be arranged on a second side of the primary hologram opposite (or facing away from) the first side.

[0027] The hologram arrangement may include a secondary hologram that can be illuminated, e.g., directly, by the illumination light. In other words, the secondary hologram may be arranged such that it is or can be illuminated by the illumination light and / or the illumination light falls on the secondary hologram.

[0028] The secondary hologram can be configured to separate the illumination light into the first portion and the second portion (and / or output it in different directions). The secondary hologram can be configured to output the first portion toward the primary hologram and the second portion toward the optical element. The secondary hologram can split the illumination light into the multiple portions for more efficient use. The secondary hologram also advantageously enables a more compact arrangement than a solution using, for example, a mirror.

[0029] The secondary hologram can be designed in such a way and / or the secondary hologram and the primary hologram can be arranged in such a way that the first portion falls on the primary hologram at a (predetermined) angle or angular range. The angle or angular range can be selected such that the primary hologram generates the holographic image in response to illumination by the first portion. In other words, the angle or angular range can correspond to an (e.g. desired) angle or angular range for which the primary hologram is designed to generate the holographic image. Through this arrangement, the first portion can be advantageously optimized for an angular range so that as little light from the first portion as possible is lost unused, e.g. light that passes through the primary hologram or is reflected by the primary hologram without contributing to the holographic image. In addition, the contrast orthe sharpness of the holographic image can be improved.

[0030] The secondary hologram can be configured to separate the illumination light into a first portion and a second portion based on wavelength. The first portion can comprise light wavelengths from one wavelength range, and the second portion can comprise light wavelengths outside the wavelength range. The wavelength range can correspond to a wavelength range for which the primary hologram is designed to generate the holographic image. This allows the first portion to be optimized so that as little light from the first portion as possible is lost unused without contributing to the holographic image. Furthermore, this can improve the contrast or sharpness of the holographic image.

[0031] The wavelength-selective separation of the first and second components also advantageously implements a spectral filter function through the secondary hologram. This makes it possible, for example, to use broadband light sources without having to provide separate (spectral) filters.

[0032] The secondary hologram can be configured to separate the illumination light into the first and second portions, such that the first portion is redirected toward the primary hologram and the second portion passes through the secondary hologram without redirection. The secondary hologram can be transparent to the second portion (or, for example, to light wavelengths outside the wavelength range). In other words, the secondary hologram can be configured to redirect and / or reflect only the first portion or light with light wavelengths within the wavelength range.

[0033] The light source, the secondary hologram and the optical element can be arranged in alignment with each other or along a common axis, wherein the secondary hologram can be arranged between the light source and the optical element.

[0034] Alternatively, the secondary hologram can be configured to separate the illumination light into the first and second portions such that the first portion passes through the secondary hologram without deflection, and the second portion is deflected toward the optical element. The secondary hologram can be transparent to the first portion (or, for example, to light wavelengths within the wavelength range). In other words, the secondary hologram can be configured to deflect and / or reflect only the second portion or light with wavelengths outside the wavelength range.

[0035] The light source, the secondary hologram, and the primary hologram can be arranged in alignment with each other or along a common axis, with the secondary hologram being arranged between the light source and the primary hologram. The lighting device can comprise an additional light source for generating additional illumination light.

[0036] The secondary hologram can be illuminated by the additional illumination light. The secondary hologram can be configured to separate the additional illumination light into a first additional portion and a second additional portion. The secondary hologram can be configured to output the first additional portion toward the primary hologram and the second additional portion toward the optical element.

[0037] For example, the secondary hologram can be designed to separate the additional illumination light into the first additional portion and the second additional portion such that the first additional portion is deflected (or reflected) towards the primary hologram and the second additional portion passes through the secondary hologram without deflection (or is transmitted by the secondary hologram without deflection).

[0038] Alternatively, the secondary hologram can be designed to separate the additional illumination light into the first additional portion and the second additional portion such that the first additional portion passes through the secondary hologram without deflection (or is transmitted by the secondary hologram without deflection) and the second additional portion is deflected (or reflected) towards the optical element.

[0039] The secondary hologram can be arranged to be illuminated simultaneously by the light source and the additional light source. The secondary hologram can be designed to superimpose the first portion and the first additional portion and / or output them simultaneously in the direction of the primary hologram. Analogously, the secondary hologram can be designed to superimpose the second portion and the second additional portion and / or output them simultaneously in the direction of the optical element. By simultaneously illuminating the secondary hologram by the light source and the additional light source and thereby simultaneously outputting the first portion and the first additional portion or the second portion and the second additional portion, e.g. as respectively superimposed light, the respective light intensities for the various functions, i.e. the generation of the holographic image and the luminous function, can be advantageously increased.Furthermore, it is conceivable to add further light properties and / or functions by illuminating with the additional light source, e.g., different colors and / or the generation of another holographic image.

[0040] The secondary hologram can be configured to separate the additional illumination light wavelength-selectively into the first additional portion and the second additional portion. The first additional portion can comprise light wavelengths from the wavelength range, and the second additional portion can comprise light wavelengths outside the wavelength range.

[0041] The lighting device can be configured to generate a holographic image of different colors and / or a lighting function of different colors, e.g., a lighting function with yellow and red light. For this purpose, the illumination light and the additional illumination light can have different light colors and / or different wavelength ranges. Alternatively, or additionally, the secondary hologram can be configured to form, through the first portion and the first additional portion, an illumination for generating the holographic image with multiple light colors and / or different wavelength ranges. The first portion and the first additional portion can have different light colors and / or wavelength ranges from one another.Furthermore, alternatively or additionally, the secondary hologram can be configured to form an illumination for generating the luminous function with multiple light colors and / or different wavelength ranges through the second portion and the second additional portion. The second portion and the second additional portion can have different light colors and / or wavelength ranges from one another.

[0042] The secondary hologram can be configured to generate illumination with multiple colors and / or different wavelength ranges, e.g., illumination with yellow and red light, by means of the second portion and the second additional portion.

[0043] The secondary hologram can comprise a (wave-selective) reflection hologram and / or a transmission hologram with a collimation function or can be designed as a reflection hologram and / or a transmission hologram with a collimation function. The transmission hologram can be a transmission hologram with edge illumination (also: edgelit transmission hologram) and / or the reflection hologram can be a reflection hologram with edge illumination (also: edgelit

[0044] reflection hologram). The secondary hologram may comprise a waveguide substrate.

[0045] The collimation function can be understood as meaning that light rays of the first portion and / or the second portion (and optionally the first additional portion and / or the second additional portion) are collimated or at least output from the secondary hologram with modified divergence angles. This can improve the beam quality of the respective portion and allow the respective portion to be utilized by the primary hologram or the optical element with the greatest possible efficiency.

[0046] It is conceivable that the secondary hologram comprises a plurality of hologram elements and optionally at least one (non-holographic) optical element. The secondary hologram can comprise, for example, a waveguide substrate (e.g., made of glass or a transparent plastic), an input hologram for coupling the illumination light into the waveguide substrate, and an output hologram for coupling the first or second portion (and optionally the first or second additional portion) out of the waveguide substrate. The output hologram can, for example, be configured to output the first portion in the direction of the primary hologram, while the second portion passes through the waveguide substrate without deflection. Alternatively, the output hologram can be configured to output the second portion in the direction of the optical element, while the first portion passes through the waveguide substrate without deflection.

[0047] By providing a waveguide substrate in conjunction with the input hologram and the output hologram, it is advantageously possible to achieve essentially any arrangement of the secondary hologram relative to the primary hologram and thus to achieve the most optimized use of available installation space.

[0048] The input hologram and the output hologram can each be designed as a wave-selective reflection hologram and / or transmission hologram.

[0049] The output hologram can be arranged on a side of the waveguide substrate facing the primary hologram or on a side of the waveguide substrate facing away from the primary hologram.

[0050] The coupling hologram can be arranged on a side of the waveguide substrate facing the light source or on a side of the waveguide substrate facing away from the light source.

[0051] The optical element may comprise a light guide and / or a light diffuser. The light diffuser may be designed to (e.g., broadly) illuminate an object.

[0052] The optical element can, for example, comprise a light guide for coupling and transmitting the second portion (and optionally the second additional portion) and a light diffuser for coupling the second portion (and optionally the second additional portion). The light guide and the light diffuser can be formed as a single piece and optionally from the same material.

[0053] The primary hologram can be a transmission hologram, a reflection hologram, an edge-lit reflection hologram or an edge-lit transmission hologram.

[0054] Furthermore, it is conceivable that the primary hologram comprises several holograms or hologram elements, e.g. depending on the desired holographic image.

[0055] The light source may, for example, comprise at least one light-emitting diode, at least one white light source and / or at least one RGB light (i.e., a light having light sources for red, green, and blue light and generating a total light formed by superposition with the corresponding spectral colors red, green, and blue).

[0056] The lighting device may comprise at least one further optical element, e.g. a collimator, which may be arranged between the light source and the secondary hologram (or between the light source and the primary hologram).

[0057] The primary hologram can be interchangeable. This allows the same arrangement of the light source and, optionally, the secondary hologram to be used to generate different holographic images or light signatures, thus advantageously simplifying the manufacture or assembly of the lighting device for different holographic images.

[0058] The lighting device may comprise a housing in which the light source, the hologram array, and the optical element are arranged, e.g., mounted. The hologram array (e.g., the primary hologram and / or the secondary hologram) and / or the optical element may be replaceably mounted in the housing.

[0059] The lighting device can be designed as a structural unit. This advantageously allows the lighting device to be pre-assembled and functional, allowing final assembly for the desired purpose, e.g., in a motor vehicle, to be carried out as simply and quickly as possible.

[0060] The lighting device can be designed as a lighting device (e.g., a rear light device) for a motor vehicle or as part of a motor vehicle lamp. The lighting device can, for example, be designed as part of an interior lighting system, a display, and / or an exterior lighting device for a motor vehicle.

[0061] The lighting device may comprise a tertiary hologram which is arranged (and optionally aligned) at a distance from the primary hologram such that it can be illuminated by a reflected portion of the first portion (or of the illumination light) which, when the primary hologram is illuminated, is reflected by a Fresnel reflection at a boundary surface of the primary hologram.

[0062] The tertiary hologram arrangement described above offers several advantages. Among other things, it enables improved and more effective use of the light generated by the light source, whereby at least a portion of the light (e.g., the first portion), which is usually lost unused, can be captured by the tertiary hologram for further purposes.

[0063] For example, holograms, such as freestanding reflection holograms, typically exhibit Fresnel reflections at a respective interface or front surface upon which an incoming light or light wave impinges. Fresnel reflections are a well-known phenomenon. These reflections depend, among other things, on the angle of incidence of the light, the polarization of the light, and the refractive index(es) of the media at the interface, and can be described by the well-known Fresnel formulas. This light reflected by Fresnel reflections does not contribute to the generation of a respective luminous function, e.g., the generation of a holographic image.

[0064] The present disclosure now offers the possibility of capturing such a light component, which is reflected by the primary hologram through Fresnel reflections, by the tertiary hologram in order to forward it for further use, for example, or to use it for another lighting function.

[0065] Furthermore, the reflected light of the Fresnel reflection has the same spectral distribution as the light used to generate the first luminous function, so that it is advantageously possible to achieve another luminous function with the same color representation.

[0066] By adjusting the angle of incidence of the illuminating light onto the primary hologram, it is possible to control how much of the illuminating light is coupled into the primary hologram (or the hologram material of the primary hologram) (via the relationship between the Fresnel formulas). This makes it possible to control how much light or radiant power of the illuminating light can (potentially) be diffracted by the primary hologram. This can also determine how much light is available to reconstruct the tertiary hologram (i.e. the reflected portion or Fresnel reflection of the primary hologram). Furthermore, by varying the angle of incidence of the illuminating light onto the primary hologram, the degree and composition of polarization can be influenced accordingly. This can apply analogously to the tertiary hologram, since Fresnel reflection can also occur there. Depending on the exposure orAt different reconstruction angles, the two holograms diffract s-polarized and p-polarized light with different efficiencies (s-polar is generally more efficient than p-polar). By cleverly combining these two relationships, the brightness of the holographic images reconstructed by the two holograms can be controlled or adjusted to each other. The size of the refractive index modulation should be chosen so that the light predominantly ends up in the 1st order of diffraction (useful order) and not in the 0th order of diffraction (unless one deliberately wants to use this, for example, for additional illumination). By varying the size of the refractive index modulations of the primary and tertiary holograms, the brightness of the holographic images reconstructed by the two holograms can also be adjusted, but with the disadvantage that a lot of light ends up in a potentially unused 0th order of diffraction.

[0067] The tertiary hologram can be configured to generate a second luminous function in response to illumination by the reflected portion. In other words, the tertiary hologram can be configured to generate a second luminous function by means of the reflected portion, e.g., by deflecting (at least a portion of) the reflected portion.

[0068] The second illumination function can be the generation (or reconstruction) of a second holographic image (or a second light signature). A second image can be recorded in the tertiary hologram, which defines the second holographic image or the second light signature and redirects and / or reflects the reflected portion of the illumination light (at least partially) in or on the tertiary hologram to generate the second holographic image. The second holographic image can be generated or can be generated outside the illumination device, e.g., freely suspended.

[0069] Thus, two separate holographic images can be created (or two separate holograms can be reconstructed) using the illuminating light, whereby the light of both images has the same spectral distribution and thus the same color representation.

[0070] The primary hologram and the tertiary hologram may be configured to generate the (first) holographic image (of the primary hologram) and the second holographic image (of the tertiary hologram) in a same direction.

[0071] The primary hologram and the tertiary hologram may be configured to generate the (first) holographic image and the second holographic image such that the (first) holographic image and the second holographic image are simultaneously perceivable by a viewer.

[0072] The tertiary hologram may be arranged facing the interface of the primary hologram.

[0073] The primary hologram can be arranged between the tertiary hologram and the light source.

[0074] The tertiary hologram can be a transmission or reflection hologram.

[0075] The tertiary hologram may be replaceable and / or arranged, e.g., (replaceably) fixed, in the housing of the lighting device.

[0076] Furthermore, a motor vehicle lamp, e.g., a motor vehicle tail lamp, is provided, wherein the motor vehicle lamp comprises the lighting device described above. The lighting function can be used (and / or configured) as a tail light, a brake light, and / or a lighting device for a vehicle license plate.

[0077] What has been described above with reference to the lighting device also applies analogously to the motor vehicle lamp and vice versa.

[0078] Optional embodiments are described below with reference to Figures 1 to 4. Figure 1 schematically shows the lighting device according to a first optional embodiment and intensity distributions of the (split) illumination light used to generate a holographic image and an additional lighting function;

[0079] Fig. 2 shows schematically the lighting device according to a second optional embodiment and intensity distributions of the (divided) illumination light;

[0080] Fig. 3 shows schematically the lighting device according to a third optional embodiment;

[0081] Fig. 4 shows schematically the lighting device according to a fourth optional embodiment;

[0082] Fig. 5 shows schematically the lighting device according to a fifth optional embodiment; and

[0083] Fig. 6 shows schematically a primary hologram of the hologram arrangement as an example of a transmission hologram, a reflection hologram, a reflection hologram with edge illumination and a transmission hologram with edge illumination.

[0084] Figure 1 shows purely schematically the lighting device 1 according to a first optional embodiment.

[0085] The lighting device 1 comprises a light source 2 for generating an illumination light 7, an optical element 3 configured to generate a lighting function 13, e.g., additional lighting, in response to illumination of the optical element 3, and a hologram arrangement 4. The optical element 3 may, for example, comprise a light guide and / or a light diffuser. The hologram arrangement 4 can be illuminated by the illumination light 7, wherein the hologram arrangement 4 is configured to separate the illumination light 7 into a first portion 7.1 for generating a holographic image 12 and a second portion 7.2 for illuminating the optical element 3.

[0086] The hologram arrangement 4 has a primary hologram 5. The primary hologram 5 is configured to generate a holographic image 12 using the first portion 7.1 of the illumination light 7.

[0087] The holographic image 12 and the luminous function 13 are only indicated in Figure 1 (and also in the subsequent Figures 2 to 4) by arrows, which schematically represent the redirected light for generating the holographic image and the light for providing the luminous function, respectively. In particular, the holographic image is not explicitly depicted in the figures.

[0088] The primary hologram 5 can be, for example, a transmission hologram, a reflection hologram, a reflection hologram with edge illumination or a transmission hologram with edge illumination, as shown by way of example in Figure 6.

[0089] Figure 6(a) shows a configuration in which the primary hologram 5 is designed as a transmission hologram. This means that the first portion 7.1 falls on one side of the primary hologram 5, is transmitted through the hologram 5, and is diffracted according to the image or grating recorded in the primary hologram 5. Finally, the diffracted light is output to generate the holographic image 12 on a side of the primary hologram 5 opposite the side onto which the first portion 7.1 falls.

[0090] Figure 6(b) shows a configuration in which the primary hologram 5 is designed as a reflection hologram. Here, the first portion 7.1 falls on the same side of the primary hologram 5 on which the diffracted light for generating the holographic image 12 is output, as the primary hologram 5 diffracts the first portion 7.1 in a corresponding light direction. Figures 6(c) and 6(d) each show the primary hologram 5 as an edge-illuminated hologram, whereby a transmission or a reflection hologram can be used as the primary hologram 5. Edge-illuminated in this case means that the first portion 7.1 is coupled into the primary hologram 5 via a side surface thereof. The primary hologram 5 is expediently designed as a light guide with a hologram, wherein the first portion 7.1 is coupled into a side surface of the light guide, propagated to the hologram and diffracted out there by the hologram.

[0091] In Figure 6(c), the first portion 7.1 is coupled to the side of the primary hologram 5 where the diffracted light is output to generate the holographic image 12. The primary hologram 5 then essentially functions as a transmission hologram. In Figure 6(d), the first portion 7.1 is coupled to the side of the primary hologram 5 opposite the side where the diffracted light is output to generate the holographic image 12. Here, the primary hologram 5 then essentially functions as a reflection hologram.

[0092] The hologram arrangement 4 further comprises a secondary hologram 6. The secondary hologram 6, which may comprise, for example, a reflection hologram and / or a transmission hologram, is arranged such that it can be illuminated by the illumination light 7. The secondary hologram 6 is further configured to separate the illumination light into the first portion 7.1 and the second portion 7.2, wherein the first portion 7.1 is output toward the primary hologram 5 and the second portion 7.2 is output toward the optical element 3.

[0093] As shown in Figure 1, the light source 2, the secondary hologram 6, and the optical element 3 are arranged in alignment with one another or along a common axis, with the secondary hologram 6 located between the light source 2 and the optical element 3. Additionally, a collimator 11 can be arranged between the light source 2 and the secondary hologram 6. The secondary hologram 6 can be designed to separate the illumination light 7 into the first portion 7.1 and the second portion 7.2 such that the first portion 7.1 is deflected toward the primary hologram 5 and the second portion 7.2 passes through the secondary hologram 6 without deflection. For example, the first portion 7.1 can be deflected such that it falls onto the primary hologram 5 at a predetermined angle, wherein the predetermined angle can be selected such that the primary hologram 5 generates the holographic image 12 in response to the illumination by the first portion 7.1.In this way, a desired angular range can be selected so that the amount of light of the first portion 7.1, which does not contribute to the holographic image 12 and is thus lost unused, is minimized.

[0094] In order to further increase the efficiency of the first part 7.1, the secondary hologram 6 can also have a collimation function so that the light rays of the first part 7.1 are output as uniformly as possible and accordingly impinge on the primary hologram 5 as uniformly as possible.

[0095] The secondary hologram 6 can further be configured to separate the illumination light 7 wavelength-selectively into the first portion 7.1 and the second portion 7.2, wherein the first portion 7.1 has light wavelengths from one wavelength range and the second portion 7.2 has light wavelengths outside the wavelength range. The wavelength range can correspond to a wavelength range for which the primary hologram 5 is designed to generate the holographic image 12. As a result, the first portion 7.1 can be optimized so that as little light as possible from the first portion 7.1 is lost unused without contributing to the holographic image 12. By minimizing the amount of light from the first portion 7.1 that passes through or is reflected by the primary hologram 5 without contributing to the holographic image 12, the contrast or sharpness of the holographic image 12 can also be improved.Figure 1 further shows an intensity distribution AO of the illumination light 7 as well as the intensity distributions A1 and A2 of the first portion 7.1 and the second portion 7.2 respectively after the separation of the illumination light 7 by the secondary hologram 6. The intensity distributions are each plotted as a function of the light wavelengths, wherein the intensity distributions A1 and A2 are further shown cumulatively to yield the intensity distribution AO in sum.

[0096] Thus, a broadband light source 2 can be used, which emits the illumination light 7 across a broad wavelength spectrum. The secondary hologram 6 can implement a spectral filter function, whereby light from a desired light wavelength range, for which the primary hologram 5 is designed to generate the holographic image 12, can be filtered out of the illumination light 7 by redirecting it. This allows the first portion 7.1 with the light of intensity distribution A1 to be selected. The remaining light outside the light wavelength range, i.e., the light of intensity distribution A2, can be used accordingly for the second portion 7.2 and thus for implementing the lighting function 13.

[0097] Figure 2 shows schematically the lighting device 1 according to a second optional embodiment.

[0098] The second embodiment differs from the first embodiment by swapping the positions of the optical element 3 and the primary hologram 5. In other words, in the second embodiment, the secondary hologram 6 is arranged between the light source 2 and the primary hologram 5.

[0099] Accordingly, the secondary hologram 6 is designed to separate the illumination light 7 into the first portion 7.1 and the second portion 7.2 such that the first portion 7.1 passes through the secondary hologram 6 without deflection, and the second portion 7.2 is deflected toward the optical element 3. Figure 2 also shows an intensity distribution AO of the illumination light 7 as well as the intensity distributions A1 and A2 of the first portion 7.1 and the second portion 7.2, respectively, after the illumination light 7 has been separated by the secondary hologram 6. Thus, the secondary hologram 6 can also implement a spectral filter function here, wherein, in this embodiment, light outside the desired light wavelength range can be filtered out of the broadband illumination light 7 by deflection. As a result, the second portion 7.2 can be selected with the light of intensity distribution A2 and output in the direction of the optical element 3.The remaining light within the light wavelength range, ie the light of intensity distribution A1, can be used accordingly for the first portion 7.1 and thus for illuminating the primary hologram 5 and thus for generating the holographic image 12.

[0100] It should be noted that the intensity distributions in Figures 1 and 2 merely have exemplary shapes that serve to explain the separation of the illumination light 7 into the two components 7.1 and 7.2. For example, the intensity distribution AO in Figure 2 can also have the shape of a (narrow) peak and, for example, include several (smaller) secondary peaks or secondary maxima.

[0101] Figure 3 schematically shows the lighting device 1 according to a third optional embodiment, which essentially corresponds to a combination of the first embodiment and the second embodiment.

[0102] The lighting device 1 comprises an additional light source 8 for generating an additional illumination light 9. The secondary hologram 6 can be illuminated by the additional illumination light 9 and is designed to separate the additional illumination light 9 into a first additional portion 9.1 and a second additional portion 9.2. The first additional portion 9.1 is output by the secondary hologram 6 in the direction of the primary hologram 5, and the second additional portion 9.2 is output by the secondary hologram 6 in the direction of the optical element 3. By simultaneously illuminating the secondary hologram 6, the light intensities of the first portion 7.1 and the second portion 7.2 can be increased due to the respective superposition by the first additional portion 9.1 and the second additional portion 9.2, respectively, whereby the holographic image 12 or the lighting function 13 can each be generated with a higher light intensity.

[0103] Furthermore, it is conceivable that the lighting device 1 can be configured to generate a multi-colored holographic image 12 and / or a multi-colored lighting function 13. For example, red and yellow light can be generated for the lighting function 13, e.g., for a brake light and a turn signal of a motor vehicle.

[0104] For this purpose, the illumination light 7 and the additional illumination light 9 can have different light colors and / or different wavelength ranges. Alternatively, or additionally, the secondary hologram 6 can be configured to form, through the first portion 7.1 and the first additional portion 9.1, an illumination for generating the holographic image 12 with multiple light colors and / or different wavelength ranges. Furthermore, alternatively, or additionally, the secondary hologram 6 can be configured to form, through the second portion 7.2 and the second additional portion 9.2, an illumination for generating the luminous function 13 with multiple light colors and / or different wavelength ranges.

[0105] Furthermore, it is conceivable to generate illumination with multiple colors or wavelength ranges at one location using the second component 7.2 and the second additional component 9.2. For example, red and yellow light can be generated, e.g., for a brake light and a turn signal of a motor vehicle.

[0106] The secondary hologram 6 can be configured to, analogously to the illumination light 7 of the light source 2, separate the additional illumination light 9 of the additional light source 7 into the first additional portion 9.1 and the second additional portion 9.2 based on wavelength. The first additional portion 9.1, like the first portion 7.1, can have light wavelengths from the wavelength range. Similarly, the second additional portion 9.2, like the second portion 7.2, can have light wavelengths outside the wavelength range.

[0107] In Figure 3, the arrangement comprising the light source 2, the primary hologram 5, the secondary hologram 6 and the optical element 3 is the first embodiment (according to Figure 1) and the arrangement comprising the additional light source 8, the primary hologram 5, the secondary hologram 6 and the optical element 3 is the second embodiment (according to Figure 2). Accordingly, the secondary hologram 6 is designed such that the first portion 7.1 is deflected towards the primary hologram 5 and the second portion 7.2 passes through the secondary hologram 6 without deflection, and at the same time the first additional portion 9.1 passes through the secondary hologram 6 without deflection and the second additional portion 8.2 is deflected towards the optical element 3.

[0108] It is conceivable, for example, that the secondary hologram 6 consists of a first hologram section for separating the illumination light 7 into the first portion 7.1 and the second portion 7.2, and of a second hologram section for separating the additional illumination light 9 into the first additional portion 9.1 and the second additional portion 9.2. The light source 2 and the secondary hologram 6 can be arranged relative to one another such that the illumination light 7 is emitted in the direction of the first hologram section. Analogously, the additional light source 8 and the secondary hologram 6 can be arranged relative to one another such that the additional illumination light 9 is emitted in the direction of the second hologram section.

[0109] In addition to the arrangement of the individual components of the lighting device 1 as shown in Figure 3, it is also possible, for example, for the arrangement of the light source 2, the primary hologram 5, the secondary hologram 6 and the optical element 3 to be the second embodiment (according to Figure 2) and for the arrangement of the additional light source 8, the primary hologram 5, the secondary hologram 6 and the optical element 3 to be the first embodiment (according to Figure 1). Accordingly, the secondary hologram 6 can be designed such that the first portion 7.1 passes through the secondary hologram 6 without deflection and the second portion 7.2 is deflected towards the optical element 3, and at the same time the first additional portion 9.1 is deflected towards the primary hologram 5 and the second additional portion 9.2 passes through the secondary hologram 6 without deflection.

[0110] Figure 4 shows schematically the lighting device 1 according to a fourth optional embodiment.

[0111] Compared to the other embodiments shown in Figures 1 to 3, the hologram arrangement 4 has only the primary hologram 5.

[0112] Accordingly, the primary hologram 5 is arranged such that it can be illuminated by the illumination light 7. Additionally, the primary hologram 5 is configured to separate the illumination light 7 into the first portion 7.1 and the second portion 7.2. The first portion 7.1 serves to generate the holographic image 12, while the second portion 7.2 is output toward the optical element 3.

[0113] The light source 2 and the primary hologram 5 can be arranged relative to one another in such a way that the illumination light 7 falls onto the primary hologram at the predetermined angle (and / or couples into the primary hologram). Alternatively, the lighting device 7 can have at least one further optical element or hologram element 10 for deflecting or reflecting the illumination light 7 (towards the primary hologram 5), wherein the further optical element or hologram element 10 can be designed and / or arranged in such a way that the illumination light 7 falls onto the primary hologram 5 at the predetermined angle. For this purpose, the primary hologram 5 can be designed in such a way that the second portion 7.2 passes through the primary hologram 5 without deflection and only the first portion 7.1 is diffracted by the primary hologram 5 for the holographic image 12. For this purpose, the primary hologram 5 can be arranged between the light source 2 and the optical element 3 orbe illuminable with the illumination light 7 on a first side of the primary hologram 5, while the optical element 3 is arranged on a second side of the primary hologram 5 opposite the first side.

[0114] For example, the optical element 3 in this embodiment can comprise a waveguide and a diffuser. For example, the zero-order illumination light 7 or light rays of the zero-order illumination light 7 (as the second portion 7.2) can be coupled into the waveguide or the substrate of the waveguide and guided to the diffuser. There, the second portion 7.2 can be scattered to illuminate an object. The object to be illuminated can be positioned such that the diffuser is not visible when looking through the holographic image 12 or the primary hologram 5 into the substrate of the waveguide.

[0115] Alternatively, it is conceivable that the optical element 3 can be arranged between the light source 2 and the primary hologram 5. The optical element 3 can be arranged and / or configured in such a way that it can be illuminated by the illumination light 7 and that it can separate the illumination light 7 into the first portion 7.1 and the second portion 7.2. The optical element 3 can, for example, be configured in such a way that the first portion 7.1 is transmitted without deflection (and output in the direction of the primary hologram 5) and the second portion 7.2 is used for the lighting function 13, e.g., by directing the second portion 7.2 to the diffuser.

[0116] The lighting device 1 according to the present disclosure, e.g., the previously described embodiments, can be designed as a structural unit. Furthermore, the lighting device 1 can be designed for a motor vehicle, e.g., as a rear lighting device, wherein the lighting function 13 can be used or configured, e.g., as a tail light, a brake light, and / or a lighting device for a vehicle license plate.

[0117] Figure 5 schematically shows the lighting device 1 according to a fifth optional embodiment, which is based on the third embodiment and additionally comprises a tertiary hologram 14.

[0118] The tertiary hologram 14 is arranged at a distance from the primary hologram 5 such that it can be illuminated by a reflected portion 7.3 of the first portion 7.1 of the illumination light 7 and a reflected additional portion 9.3 of the first additional portion 9.1 of the additional illumination light 9, which are reflected by a Fresnel reflection at a boundary surface 5.1 of the primary hologram 5 when the primary hologram 5 is illuminated.

[0119] The tertiary hologram 14 is arranged facing the interface 5.1 of the primary hologram 5, wherein the primary hologram 5 is arranged between the tertiary hologram 14 and the light source 2.

[0120] The tertiary hologram 14 can be configured to generate a second holographic image 15 in response to illumination by the reflected portion 7.3 and the reflected additional portion 9.3. For example, a position and orientation of the tertiary hologram 14 (relative to the primary hologram 3) can be selected such that the second holographic image 15 generated by the tertiary hologram 14 has maximum light intensity, maximum contrast, and / or maximum image sharpness.

[0121] The primary hologram 5 and the tertiary hologram 14 can be configured to generate the holographic image 12 and the second holographic image 15 in the same direction and / or to generate them in such a way that the holographic image 12 and the second holographic image 15 are simultaneously perceivable by a viewer. Analogous to the arrangement in Figure 5, it is also conceivable to additionally equip the first, second, or fourth embodiment with the tertiary hologram in order to utilize light reflected by the primary hologram 5 to generate the second holographic image 15.

[0122]

[0123] 1 lighting device

[0124] 2 light source

[0125] 3 optical element

[0126] 4 Hologram arrangement

[0127] 5 primary hologram

[0128] 6 secondary hologram

[0129] 7 Illumination light

[0130] 7.1 first part of the illumination light

[0131] 7.2 second part of the illumination light

[0132] 7.3 reflected portion of the first portion of the illumination light

[0133] 8 additional light sources

[0134] 9 additional lighting light

[0135] 9.1 first part of the additional illumination light

[0136] 9.2 second part of the additional illumination light

[0137] 9.3 reflected portion of the first portion of the additional illumination light

[0138] 10 additional optical element or hologram element

[0139] 11 Collimator

[0140] 12 holographic image or redirected light to generate the holographic image

[0141] 13 Lighting function or light to provide the lighting function

[0142] 14 tertiary hologram

[0143] 15 second holographic image or deflected light for generating the second holographic image

[0144] AO, A1 , A2 intensity distributions

Claims

Patent claims 1. Lighting device (1 ), wherein the lighting device (1 ) comprises: - a light source (2) for generating an illuminating light (7); and - a hologram arrangement (4) which can be illuminated by the illuminating light (7), wherein the hologram arrangement (4) is designed to: - to separate the illumination light (7) into a first portion (7.1) for generating a holographic image (12) and a second portion (7.2) for generating a luminous function (13).

2. Lighting device (1) according to claim 1, wherein: - the lighting device (1 ) comprises: - an optical element (3) designed to generate the lighting function (13) in response to illuminating the optical element (3) by means of the second portion (7.2) of the illuminating light (7); and - the hologram arrangement (4) comprises: - a primary hologram (5) designed to generate a holographic image (12) by means of the first portion (7.1) of the illumination light (7).

3. Lighting device (1) according to claim 2, wherein the primary hologram (5) is illuminable by the illuminating light (7) and is designed to: - to separate the illumination light (7) into the first part (7.1) and the second part (7.2); and - to output the second portion (7.2) in the direction of the optical element (3).

4. Lighting device (1) according to claim 3, wherein - the primary hologram (5) is designed such that the second portion (7.2) passes through the primary hologram (5) without deflection; and / or - the primary hologram (5) is arranged between the light source (2) and the optical element (3); and / or - the primary hologram (5) can be illuminated with the illumination light (7) on a first side of the primary hologram (5), and the optical element (3) is arranged on a second side of the primary hologram (5) opposite the first side.

5. Lighting device (1) according to claim 2, wherein the hologram arrangement (4) has: - a secondary hologram (6) which can be illuminated by the illuminating light (7) and is designed to: - to separate the illumination light into the first part (7.1) and the second part (7.2); - the first part (7.1 ) in the direction of the primary hologram (5) to issue; and - to output the second portion (7.2) in the direction of the optical element (3).

6. Lighting device (1 ) according to claim 5, wherein the secondary hologram (6) is designed to: - to separate the illumination light (7) wavelength-selectively into the first portion (7.1) and the second portion (7.2), wherein the first portion (7.1) has light wavelengths from one wavelength range and the second portion (7.2) has light wavelengths outside the wavelength range.

7. Lighting device (1) according to claim 5 or 6, wherein the secondary hologram (6) for separating the illumination light (7) into the first part (7.1) and the second part (7.2) is designed such that - the first portion (7.1) is deflected towards the primary hologram (5) and the second portion (7.2) passes through the secondary hologram (6) without deflection; or - the first portion (7.1) passes through the secondary hologram (6) without deflection and the second portion (7.2) is deflected towards the optical element (3).

8. Lighting device (1) according to one of claims 5 to 7, wherein - the lighting device (1 ) comprises: - an additional light source (8) for generating an additional illumination light (9); and - the secondary hologram (6) can be illuminated by the additional illumination light (9) and is designed to: - to separate the additional illumination light (9) into a first additional component (9.1) and a second additional component (9.2); - to output the first additional portion (9.1) in the direction of the primary hologram (5); and - to output the second additional portion (9.2) in the direction of the optical element (3).

9. Lighting device (1) according to claim 8, when dependent on claim 6, wherein the secondary hologram (6) is designed to: - to separate the additional illumination light (9) wavelength-selectively into the first additional portion (9.1) and the second additional portion (9.2), wherein the first additional portion (9.1) has light wavelengths from the wavelength range and the second additional portion (9.2) has light wavelengths outside the wavelength range.

10. Lighting device (1) according to claim 8 or 9, wherein - the illuminating light (7) and the additional illuminating light (9) have different light colours and / or different wavelength ranges; and / or - the secondary hologram (6) is designed to form, by means of the first portion (7.1) and the first additional portion (9.1), an illumination for generating the holographic image (12) with a plurality of light colors and / or different wavelength ranges; and / or - the secondary hologram (6) is designed to form, by means of the second portion (7.2) and the second additional portion (9.2), an illumination for generating the luminous function (13) with a plurality of light colors and / or different wavelength ranges.

11. Lighting device (1) according to one of claims 8 to 10, wherein the secondary hologram (6) for separating the additional illumination light (9) into the first additional portion (9.1) and the second additional portion (9.2) is designed such that - the first additional portion (9.1) is deflected towards the primary hologram (5) and the second additional portion (9.2) passes through the secondary hologram (6) without deflection; or - the first additional portion (9.1) passes through the secondary hologram (6) without deflection and the second additional portion (9.2) is deflected towards the optical element (3).

12. Lighting device (1) according to one of claims 5 to 11, wherein the secondary hologram (6) comprises a reflection hologram and / or a transmission hologram with collimation function, optionally with edge illumination and / or comprising a waveguide substrate.

13. Lighting device (1) according to one of the preceding claims, wherein the optical element (3) comprises a light guide and / or a light diffuser.

14. Lighting device (1) according to one of the preceding claims, wherein the primary hologram (5) is a transmission hologram, a reflection hologram, an edge-illuminated reflection hologram or an edge-illuminated transmission hologram.

15. Motor vehicle lamp, the motor vehicle lamp comprising: - a lighting device (1) according to one of the preceding claims, wherein the lighting function (13) can be used as a tail light, a brake light and / or a lighting for a vehicle license plate.

Images