Functionalized diffuser element for a display system

Abstract

An optical arrangement (91) for a head-up display system (90) on a deflection surface (190) comprises at least one projection unit (121), which is designed to project at least one image onto at least one functionalized diffuser element (122).

Description

[0001] DESCRIPTION

[0002] FUNCTIONALIZED DIFFUSER ELEMENT FOR DISPLAY SYSTEM

[0003] TECHNICAL AREA

[0004] Several examples of the disclosure relate to an optical arrangement for a display system, for example a head-up display or a digital instrument panel. Several examples relate in particular to the use of a functionalized diffuser element.

[0005] BACKGROUND

[0006] Head-up displays (HUDs; also known as windshield display devices) are used, for example, in vehicles to create a virtual image so that the driver does not have to take their eyes off the road. The HUD includes a projection unit and a wavefront manipulator.

[0007] The projection unit generates the optical information (e.g., speed, navigation instructions, warnings, etc.) used to create a virtual image. Typically, the projection unit is a compact projector mounted below the vehicle's dashboard. It uses either lasers, LEDs, or digital light processing (DLP) technology to create the virtual images.

[0008] The wavefront manipulator is an optical component that manipulates the light rays generated by the projection unit to produce a sharp and clearly visible virtual image. The wavefront manipulator can consist of lenses, mirrors, or one or more holographic optical elements (HOEs).

[0009] Unlike a real image displayed on a physical surface (e.g., a screen), a virtual image is generated on a virtual image plane located behind the windshield (i.e., in the vicinity of the vehicle), starting from the eyebox. The eyebox is the area in which the driver can see the virtual image clearly. In a digital instrument cluster, the virtual image can be freely suspended within a cavity formed in the vehicle's dashboard.

[0010] The following prior art is known: CN112946890A; DE102012222421 A1 ; DE102019131732A1 ; JPH08286139A; WO2023186627A1 .

[0011] SUMMARY

[0012] One objective of the present disclosure is to provide an optical arrangement for a display system that has compact dimensions and good optical properties, in particular high brightness and good contrast of the virtual image in the eyebox. The disclosure described herein is intended to enable display systems for use in a motor vehicle, for example, for a head-up display (HUD) or for a digital instrument panel in a vehicle dashboard.

[0013] This task is solved by the features of the independent claims. The dependent claims define embodiments.

[0014] An optical arrangement for a display system on a deflecting surface, e.g., a motor vehicle windshield or a deflecting lens arranged on a motor vehicle dashboard, is disclosed. If a virtual image is projected into the driver's field of vision while the driver is perceiving the vehicle's surroundings, the corresponding display system is referred to as a head-up display (HUD) system or simply HUD. If the driver turns their gaze away from the vehicle's surroundings and views an instrument panel on the vehicle's dashboard, a corresponding display system is typically referred to as a digital instrument panel (or simply digital instrument panel).Regardless of the specific system integration – that is, whether the optical arrangement is used for a HUD or a digital instrument panel – similar or identical setups, as described below, can be used for the optical arrangement.

[0015] The optical arrangement includes at least one projection unit. This projection unit is configured to project at least one image onto at least one functionalized diffuser element. The projection unit is configured to emit light along at least one beam path. The projection unit can, for example, use DLP technology. A digital micro mirror device (DMD) array could be used. The projection unit could, for example, use a liquid crystal display, such as an LCOS display (liquid crystal on silicon).

[0016] The optical arrangement also includes the at least one functionalized diffuser element, which is arranged along the at least one beam path. The at least one functionalized diffuser element is arranged such that it disperses the at least one beam path. In this way, a virtual image of the at least one picture, which is projected onto the functionalized diffuser element, becomes perceptible or visible in an eyebox of the display system. The virtual image appears – as perceived from the eyebox – behind the deflecting surface. Each of the at least one functionalized diffuser element can be formed in one piece, i.e., integrally shaped. If several functionalized diffuser elements are present, they can be formed in one piece; however, it would also be conceivable that several functionalized diffuser elements are not integrally shaped, i.e., that, for example, several separate substrates are used.

[0017] A diffuser element scatters light. It has a multitude of scattering centers. When parallel light rays strike a scattering center of a diffuser element, they are scattered in different directions, thus producing diffuse light. The type of scattering can also be described as the scattering characteristic. The scattering characteristic describes, for example, a specific angular distribution under which the light striking the diffuser element is scattered (scattering lobe). The diffuser element can therefore also be used to redirect the light by appropriately orienting the scattering lobe. Furthermore, the diffuser element can be used to reduce the divergence of the light path by creating a scattering lobe with a width smaller than the divergence of the light path before it reaches the diffuser element.

[0018] A simple diffuser element is a ground glass screen. Such a screen exhibits the same scattering characteristics at various lateral positions within its aperture. This is achieved through a microscopically random orientation of the scattering centers, so that on average all scattering directions occur with equal frequency. For example, the scattering lobe shows no dependence on the lateral position within the aperture of the ground glass screen. The scattering characteristics also show no dependence on, for example, the wavelength or polarization of the incident light. For these reasons, the ground glass screen is not a functionalized diffuser element.

[0019] In contrast, a functionalized diffuser element exhibits a scattering characteristic that depends on the lateral position within the aperture and / or the wavelength and / or the polarization of the incident light. A functionalized diffuser element can alternatively or additionally exhibit a non-uniform scattering characteristic. Thus, there is always a macroscopic order to the scattering. With a functionalized diffuser element, the scattering centers can be generated in a specific process. For example, a functionalized diffuser element can have a control characteristic with multiple maxima, meaning it preferentially scatters light in certain directions; this is a deviation from equally probable scattering in all directions within a spatial region. For instance, it would be conceivable that a functionalized diffuser element on a microscopic scale—i.e.,On a length scale corresponding to the order of the scattered light, a random scattering characteristic still exists; however, due to a macroscopic ordering of the scattering centers on the macroscopic scale, certain scattering directions are favored. In other words, this means that with a functionalized diffuser element, the scattering characteristic, e.g., the scattering lobe, is specifically tuned to certain properties that are required or advantageous for the optical system.

[0020] By using at least one functionalized diffuser element, an eyebox can be appropriately designed. This at least one functionalized diffuser element can concentrate the radiant power of the beam path towards the eyebox, thereby brightening the perceived image. For example, the lateral dimensions or size of the eyebox can be adjusted to prevent it from being too small or too large. By appropriately adjusting the scattering characteristics of the at least one functionalized diffuser element, the eyebox can be positioned and / or dimensioned appropriately. Stray light emitted by the at least one projection unit that does not reach the eyebox can be reduced.This allows the brightness of the virtual image, as perceived from the eyebox, to be increased compared to a reference implementation without functionalized diffuser elements, while maintaining the same light output from at least one projection unit.

[0021] The at least one functionalized diffuser element can, for example, be at least one holographic diffuser element. Each of the at least one holographic diffuser element can be assigned to a corresponding beam path, thus scattering a respective beam path along which light is emitted by the at least one projection unit.

[0022] A holographic diffuser element has a holographic optical element (HOE). The HOE forms the scattering surface. A holographic diffuser element achieves scattering of at least one beam path by diffraction of the light at the HOE. This means that, unlike a classical diffuser element, the holographic diffuser element does not have microscopic scattering centers; instead, an effect comparable to scattering (see the description of scattering above) is achieved through diffraction of the light. The HOE exhibits spatial modulation of the refractive index. This spatially variable refractive index forms a diffraction pattern, sometimes also called a diffraction grating. This grating diffraction pattern diffracts the incident light, provided its wavelength matches the periodicity of the diffraction pattern. The HOE is therefore wavelength-selective, so that the scattering characteristics differ for different wavelengths of the incident light.For example, the HOE can selectively scatter light within a relatively limited wavelength range, such as 0.5 to 30 nm. To scatter light across multiple wavelength ranges, it would be possible to use several HOEs or multiple holographic diffuser elements, for example, stacked together. This would allow for diffraction of light across multiple wavelength ranges, such as red (620-630 nm), green (520-530 nm), and blue (420-430 nm). The wavelength range can be adjusted depending on the application. This includes both the position and width of the wavelength range (selectivity). The HOE can optionally act selectively on light of a specific polarization, such as left- or right-circularly polarized. It can also optionally act selectively on light incident at a specific angle. Examples of polarization-sensitive HOE designs include...Described in Weng, Yishi, et al. “Polarization volume grating with high efficiency and large diffraction angle.” Optics Express 24.16 (2016): 17746-17759. Corresponding techniques can also be used to create a holographic diffuser element that selectively scatters light with a specific polarization.

[0023] The use of holographic diffuser elements offers certain advantages. For example, holographic diffuser elements can be manufactured with particularly large areas. This enables large virtual images even with relatively short projection lengths and large distances between the eyebox and the image plane of the virtual image, up to and including a virtual image positioned at infinity (for example, in combination with a microlens array). Holographic diffuser elements can be manufactured in a replication process, where a holographic master (e.g., using a contact printing process) is replicated. Holographic diffuser elements can be functionalized with great flexibility. For example, variable wavelength selectivity can be implemented, depending on the system integration requirements. Furthermore, it is possible to integrate a corresponding system with a smaller footprint.The use of holographic diffuser elements enables, for example, an optical arrangement for a HUD that requires significantly less installation space than a reference arrangement using a freeform mirror. The eyebox can be defined with a limited extent by using holographic diffuser elements. The eyebox can also be specially shaped, for example, with a curvature.

[0024] The at least one holographic diffuser element can comprise several holographic diffuser elements. These can be configured to diffract light with different wavelengths and / or different angles of incidence and / or different polarizations.

[0025] The multiple holographic diffuser elements can therefore be assigned to different optical channels. This allows for the targeted diffraction of multiple beam paths to varying degrees. It would also be possible to generate multicolored virtual images. It would be conceivable to operate multiple eyeboxes. It would be possible to generate multiple virtual images at varying distances from the eyebox using multiple holographic diffuser elements.

[0026] In this way, a sense of depth can be conveyed to the viewer.

[0027] In principle, it would be conceivable to use multiple projection units, each projecting different images onto different functionalized diffuser elements. For example, projection units could be positioned on different sides of the functionalized diffuser elements. This would allow for a compact design and system integration within a limited installation space.

[0028] Due to the selectivity in the diffraction of light, it is possible, but not necessary, for the multiple holographic diffuser elements to be stacked. A first holographic diffuser element can therefore extend along a second holographic diffuser element. This allows for a particularly compact design of the optical arrangements.

[0029] If the multiple holographic diffuser elements are stacked, a gap or space can be provided between them within the stack. It is not necessary in all variations for the multiple holographic diffuser elements to be stacked, meaning they do not extend in parallel planes at a constant distance. For example, it would also be conceivable for the first of the multiple holographic diffuser elements to be curved, while the second is flat. This allows for the creation of a targeted depth impression through the associated virtual images. In such a case, the distance between the two holographic diffuser elements varies due to the curvature of the first element, depending on its lateral position.

[0030] By means of such a curvature of at least one of the one or more holographic (or more generally, one or more functionalized) diffuser elements, it is possible—in addition to creating a desired depth impression of the virtual image—to alternatively or additionally compensate for the curvature of the deflecting surface (e.g., the windshield) or at least counteract it. For example, in some variants it may be desirable for the virtual image to be perceived with a specific curvature, or even with a flat curvature, while the windshield has a curvature that differs from this specific curvature. In this case, the curvature of the one or more functionalized diffuser elements can be chosen to correlate with the curvature of the windshield, thus compensating for it.For example, if the deflecting surface is convexly curved, the diffuser surface of the functionalized diffuser element can also be convexly curved (relative to the direction of incidence of the light emanating from the projection unit). Similarly, if the deflecting surface is concavely curved, the diffuser surface of the functionalized diffuser element can also be concavely curved (again, relative to the direction of incidence of the light emanating from the projection unit).

[0031] Another variant involves several holographic diffuser elements that are flat but tilted relative to each other. In such a case, the distance between the two holographic diffuser elements varies as a function of their lateral position due to the tilt. Yet another variant involves a one-dimensional or two-dimensional tilt of one or more holographic diffuser elements (or, more generally, one or more functionalized diffuser elements) relative to the deflecting surface. This means that the diffuser surface of a functionalized diffuser element has different distances to the deflecting surface, depending on its position on the diffuser surface. Such a tilt of the diffuser surface relative to the deflecting surface can, in particular, compensate for the tilt of the deflecting surface with respect to the virtual image.The virtual image, when perceived from the eyebox, is then, for example, vertically oriented in space (after system integration, for instance in a vehicle) and does not itself exhibit the tilt of the deflecting surface. This allows the tilt caused by system integration in the deflecting surface to be compensated for, achieving the desired spatial arrangement of the virtual image.

[0032] The virtual images of multiple holographic diffuser elements can implement different color channels (for example, red, green, and blue) of a common scene. Due to the offset in the depth direction—for example, the gap in stacked holographic diffuser elements—the image planes of the different virtual images of the multiple color channels can be offset relative to each other, creating a depth impression in the common scene. This means, for example, that the image plane of the blue color channel may appear closer or farther away from the eyebox than the image plane of the red color channel, to give just one example. For a clear depth impression, such a gap should be no smaller than 10% of the side lengths (corresponding to the aperture size, which correlates with the lateral extent of the virtual images) of the multiple holographic diffuser elements.

[0033] Multiple holographic diffuser elements (or, more generally, multiple functionalized diffuser elements) can be integrated into a single substrate. Multiple holographic diffuser elements (or, more generally, multiple functionalized diffuser elements) can be manufactured as a single piece. For example, volume HOE can be used within a single substrate. This means that a multitude of volume HOE can be stacked or laterally offset within a single substrate. This enables compact integration and simplified manufacturing. The at least one holographic diffuser element can be arranged in the beam path, for example, in a free-ray geometry or an edge-lit geometry. In edge-lit geometry, the light is coupled into the substrate via a side surface.The beam path then runs between the side surface and the scattering surface (which is tilted relative to the side surface) in the substrate.

[0034] Multiple holographic diffuser elements can operate different optical channels. For example, different projection units can be used for the different optical channels. Different optical channels can also operate different eyeboxes, either alternatively or additionally. For instance, a first eyebox, operated by a first optical channel, could be intended for the driver of a vehicle, and a second eyebox, operated by a second optical channel, could be intended for a passenger.

[0035] The multiple functionalized diffuser elements (for example, holographic diffuser elements) can be configured to separate two or more beam paths. This means that the scattering lobes of the different diffuser elements can be oriented in such a way as to separate the different beam paths. This allows, for example, the operation of multiple eyeboxes. A separate beam splitter, etc., is not necessary, thus enabling a compact design.

[0036] However, it would also be conceivable in general that several beam paths are combined through the diffuser elements.

[0037] The at least one functionalized diffuser element can be designed to better concentrate the light field into a limited solid angle. The scattering lobe can be particularly small. For example, a scattering lobe can be used that emits light only into a solid angle of 1° or no more than 5°. The divergence of a beam path dispersed by a functionalized diffuser element can be greater upstream of the functionalized diffuser element than downstream. In this way, the brightness of the virtual image can be increased while maintaining the same light output. Less stray light is lost. By reducing stray light, the distraction of people in the vicinity can also be reduced.

[0038] The at least one functionalized diffuser element is configured, for example, to redirect the at least one beam path to at least one eyebox of the HUD. This means that the at least one functionalized diffuser element can also have a redirection functionality. The angle of incidence of light onto the functionalized diffuser element can differ from the angle of reflection of the light. For example, the scattering lobe of the at least one functionalized diffuser element may not be oriented perpendicular to the scattering surface of the at least one functionalized diffuser element, but rather tilted relative to a corresponding plane normal. The corresponding angle of the scattering lobe can also vary as a function of the lateral position within the scattering surface. This can, for example, eliminate the need for a separate mirror to redirect the beam path.This allows the overall space required for the optical arrangement to be reduced.

[0039] Furthermore, by using a scattering lobe that varies as a function of the lateral position within the scattering area, it is possible to direct light over an extended area towards a specific eyebox. This allows for the generation of particularly large lateral images, while reducing the number of projection units compared to reference implementations. For example, it would be conceivable to use a single projection unit.

[0040] At least one of the at least one diffuser element can be in

[0041] The diffraction geometry should be arranged in a transmission pattern. This means that the beam path passes through the scattering surface of the respective diffuser element. Alternatively, it would also be conceivable that at least one of the at least one functionalized diffuser element could be arranged in a reflection pattern within the beam path.

[0042] It is possible that the optical arrangement includes one or more additional optical elements in at least one beam path.

[0043] The optical arrangement can, for example, include a deflecting element. This element is arranged, for instance, along the at least one beam path downstream from the at least one functionalized diffuser element (i.e., between the at least one functionalized diffuser element and the deflecting surface). The deflecting element is designed to redirect the at least one beam path. The deflecting element can be, for example, a prism or a mirror. The deflecting element allows for a particularly small installation space for the optical arrangement, which can be especially helpful for system integration, for example, beneath the dashboard of a motor vehicle.

[0044] For example, it would be conceivable that the deflecting element is arranged such that the at least one beam path forms a loop. This means that a first section of each beam path is intersected by a second section of the same beam path. In this way, a relatively long beam path can be enabled, which can be helpful for allowing large projection distances, i.e., distances between the at least one functionalized diffuser element and the image plane of the virtual image.

[0045] The optical arrangement can, for example, include a microlens array. This array can extend along the at least one functionalized diffuser element. A microlens array comprises a multitude of microlenses arranged side by side, each refracting the light. The microlens array can be positioned at a specific distance from the HOE of the functionalized holographic diffuser element. For instance, the microlens array could be positioned at a distance from the HOE corresponding to the "focal length" of the HOE. This causes the projected image on the HOE to be mapped to infinity, resulting in a so-called "infinity display": the virtual image is perceived at infinity.

[0046] The microlens array can extend along a scattering surface of the diffuser element. The microlens array can, for example, be applied to a suitably functionalized diffuser element. A refractive index-matched adhesive can be used for this purpose.

[0047] For example, each microlens of the microlens array can be assigned to a corresponding sub-area on the scattering surface of the functionalized diffuser element. The projection unit can be configured to project all the image information of the virtual image onto each sub-area. In other words, each sub-area is assigned to multiple projection pixels of the projection unit. The same image information is projected onto each sub-area. This projection mode differs from the projection mode used when no microlens array is present. When no microlens array is present, the virtual image is projected onto the functionalized diffuser element in such a way that it fills the entire scattering surface. In other words, the virtual image is then projected onto the functionalized diffuser element in such a way that it completely or predominantly fills the aperture of the functionalized diffuser element.

[0048] The at least one functionalized diffuser element can have a curved scattering surface. The curvature of the scattering surface creates a depth impression for the virtual image. This is because different areas of the scattering surface are positioned closer to or further away from the eyebox. To convey a particularly pronounced depth impression, the curvature can be comparatively strong. For example, the curvature could create an offset along the beam path of two points on the scattering surface that is no less than 10% of one side length of the scattering surface. A curved scattering surface can be easily produced, especially for holographic diffuser elements. This may be due to the manufacturing process of holographic diffuser elements.

[0049] A display system is also disclosed. This includes the optical arrangement and the deflection surface. The display system could, for example, be a head-up display (HUD) system. However, the display system could also be a display system for a digital instrument panel. The display system could implement a digital instrument panel for a motor vehicle.

[0050] The deflecting surface can be transparent. The deflecting surface can be a motor vehicle windshield.

[0051] The deflecting surface could also be a disc that is formed in a cavity or hollow space in the dashboard of a motor vehicle.

[0052] For example, the cavity can be elongated, meaning it extends in a longitudinal direction. This longitudinal direction could, for instance, run along the length of the dashboard. This means that the longitudinal direction could extend from the left driver's door to the right passenger's door. The deflecting surface can be designed as a deflecting disc and arranged within the cavity. The deflecting disc is also elongated.

[0053] For example, the cavity can have a darkened back panel. Such a display system for a digital instrument panel in a vehicle's dashboard can create the effect of a freely floating image within the cavity. In contrast to conventional analog instrument panels or even conventional digital instrument panels that use a screen, this can convey an enhanced sense of depth.

[0054] The deflecting surface could include a functional reflective element. This functional reflective element has reflective properties that exceed those of a normal mirror. For example, a specific direction or angular distribution can be defined. It could also have an asymmetric reflectance, such as a "one-way mirror." This would prevent additional stray light and increase the brightness with which the viewer perceives the virtual image. Alternatively, the light beam, originating from the projection unit, could first strike the back side of the deflecting surface; then pass through the deflecting surface and the functional reflective element with its asymmetric reflectance (because light coming from the back side is not significantly deflected or reflected); subsequently be dispersed by the diffuser element and redirected back towards the deflecting surface.The light beam then strikes the functional reflective element and is reflected or deflected by it towards the eyebox. The functional reflective element can, for example, be a one-way mirror, comprising, for instance, a stack of layers including a metallic layer and an antireflective coating. Alternatively, the functional reflective element could be a holographic optical element that deflects the light by diffraction. For example, the holographic optical element could be designed to diffract and deflect the light when it enters the element from the diffuser, but not when it enters the element from the opposite direction.

[0055] The components of the display system are arranged and set up to provide at least one eyebox.

[0056] A motor vehicle equipped with such a display system is also revealed.

[0057] For example, the system could have a backside darkening on one side of the deflecting surface that is opposite the side of the deflecting surface where at least one beam path is reflected. This would increase the contrast of the virtual image.

[0058] The features set out above and those described below can be used not only in the corresponding explicitly set out combinations, but also in further combinations or in isolation, without leaving the scope of protection of the present invention.

[0059] BRIEF DESCRIPTION OF THE FIGURES

[0060] FIG. 1 illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0061] FIG. 2 illustrates an exemplary dependence of the scattering lobe of a functionalized diffuser element for different positions in the aperture of the functionalized diffuser element. FIG. 3 illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0062] FIG. 4A illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0063] FIG. 4B illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0064] FIG. 5 illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0065] FIG. 6 illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0066] FIG. 7A illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0067] FIG. 7B illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0068] FIG. 7C is a perspective view of an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0069] FIG. 8 illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0070] FIG. 9 illustrates an exemplary variant of an optical arrangement for a HUD display system according to various examples.

[0071] FIG. 10 illustrates an exemplary system integration of an optical arrangement for a HUD display system according to various examples.

[0072] FIG. 11 illustrates an exemplary system integration of an optical arrangement for a HUD display system according to various examples.

[0073] FIG. 12 schematically illustrates the scattering of light (left) and the refraction of light (right).

[0074] FIG. 13 illustrates a variant of an optical arrangement for a digital instrument panel according to various examples. FIG. 14 illustrates a variant of an optical arrangement for a digital instrument panel according to various examples.

[0075] FIG. 15 illustrates a variant of an optical arrangement for a digital instrument panel according to various examples.

[0076] FIG. 16 illustrates a variant of an optical arrangement for a digital instrument panel according to various examples.

[0077] FIG. 17 illustrates a variant of an optical arrangement for a digital instrument panel according to various examples.

[0078] FIG. 18 is a top view of a variant of an optical arrangement for a digital display board according to various examples.

[0079] FIG. 19 is a top view of a reference implementation of an optical arrangement for a digital display board according to various examples.

[0080] FIG. 20 schematically illustrates an exemplary variant in which a functionalized diffuser element is integrated with a projection unit.

[0081] DETAILED DESCRIPTION

[0082] The properties, features and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings.

[0083] FIG. 1 illustrates a HUD display system 90. The HUD display system 90 comprises a windshield 190 of a motor vehicle, which incorporates a deflecting surface and has an inner surface 191 (facing the interior) and an outer surface 192 (facing the environment). The windshield 190 is shown in section. Furthermore, in the illustrated example, the HUD display system 90 has a back-side darkening 195 in an area of ​​the windshield 190 near its lower edge (facing the dashboard). The back-side darkening 195 (also referred to as "black backing") can be provided, for example, in the form of a black or gray coating or film. This is optional: it is also possible to omit the back-side darkening 195.

[0084] The HUD display system 90 also includes an optical arrangement 91 with a projection unit 121. The projection unit 121 is configured to project an image onto a functionalized diffuser element 122 by emitting light along a beam path 130. The functionalized diffuser element 122 is configured to diffuse the beam path 130. In the example shown in FIG. 1, the functionalized diffuser element 122 is arranged in transmission geometry within the beam path 130 (but could also be arranged in reflection geometry within the beam path 130).

[0085] The functionalized diffuser element 122 can be formed in a substrate, in particular in a one-piece substrate. The functionalized diffuser element 122 can be configured such that the scattering characteristic exhibits a dependence on a position along the surface of the functionalized diffuser element 122 in order to form an eyebox 95. Details are described below.

[0086] Figure 1 shows how two light rays from the beam path 130 strike two exemplary scattering centers 398, 399 of the functionalized diffuser element 122. The two scattering centers 398, 399 are located at different positions within the functionalized diffuser element 122. The light is scattered at the scattering centers 398, 399. However, the scattering lobes at the scattering centers 398, 399 are oriented differently. This results in the functionalized diffuser element 122 reducing the divergence of the beam path 130 when viewed across the entire aperture of the functionalized diffuser element 122. Between the projection unit 121 and the diffuser element 122, the width 395 of the light field along the beam path increases significantly (dashed arrow). Downstream of the diffuser element 122, the width 396 of the light field remains approximately constant (dotted arrow).The windshield 190, in conjunction with the location-dependent scattering characteristic of the functionalized diffuser element 122 (i.e., the differently oriented scattering lobes of the scattering centers 398, 399), then achieves focusing, i.e., the beam path 130 is convergent. Furthermore, the functionalized diffuser element is designed to deflect the beam path 130 towards the eyebox 95: the angle of incidence of the beam path 130 differs from the angle of reflection of the beam path 130. The virtual image 96 is also shown in FIG. 1.

[0087] The deflection of the beam path 130 is achieved by varying the angle of incidence of the beam path 130 on the windshield 190 depending on the field position. For example, FIG. 2 illustrates different scattering lobes 311, 312 for the functionalized diffuser element 122 from the example in FIG. 1. It can be seen there that the scattering lobe 311 on one side of the aperture of the functionalized diffuser element 122 is tilted more sharply at the scattering centers 398, or on one side of the field, relative to a plane normal 305 of a scattering plane 301 of the functionalized diffuser element 122 than the scattering lobe 312 on the other side of the aperture at the scattering centers 399. Furthermore, the scattering lobe 311 is wider than the scattering lobe 312.In general terms, the spatial dependence of the scattering characteristic of the functionalized diffuser element 122 can compensate for different distances between the functionalized diffuser element 122 and the inner surface 191 of the windshield 190, where the beam path 130 is reflected. Different angles of incidence on the windshield can also be compensated. Furthermore, the perceptibility of the virtual image 96, or a beam path converging towards the eyebox 95, is enabled. The dependence of the scattering characteristic shown in FIG. 2 is only an example intended to illustrate qualitative and quantitative relationships, but should not be understood as limiting.

[0088] Referring again to FIG. 1: there, the functionalized diffuser element 122 is illuminated in free-ray geometry. However, this is only one example. Another variant is shown in FIG. 3. In the HUD display system 90 in the variant of FIG. 3, the functionalized diffuser element 122 is integrated into an optical block (e.g., a flat plate) or a substrate 150. For example, the functionalized diffuser element 122 can be a holographic diffuser element, which is implemented by a volume HOE on one side of the substrate 150 facing the windshield 190. The substrate 150 has two opposing side surfaces 151, 152. The beam path 130 is coupled into the substrate 150 via the side surface 151. The beam path 130 then runs in the substrate 150 from the side surface 151 to the functionalized diffuser element 122, but without being reflected at any other outer surfaces of the substrate 150. In FIG.3 the functionalized diffuser element 122 is thus arranged in edge-lit geometry in the beam path 130.

[0089] FIG. 4A schematically illustrates another variant of the HUD display system 90 or the optical arrangement 91. The optical arrangement 91 in the variant of FIG. 4A comprises several optical channels. A first optical channel is associated with a first beam path 130-1, and a second optical channel is associated with a second beam path 130-2. The first optical channel has a first projection unit 121-1, and the second optical channel has a second projection unit 121-2. For example, it would be conceivable that the first projection unit 121-1 emits light in a first wavelength range, while the second projection unit 121-2 emits light in a second wavelength range, the first wavelength range being different from the second wavelength range. For example, the first projection unit 121-1 could emit red light, and the second projection unit 121-2 could emit blue light, to give just one example.The first optical channel has a first functionalized diffuser element 122-1, and the second optical channel has a second functionalized diffuser element 122-2. In the example of FIG. 4A, the two diffuser elements 122-1, 122-2 (e.g., holographic diffuser elements) are each arranged in a free-ray geometry at the beam paths 130-1, 130-2, but other variants are also conceivable.

[0090] In FIG. 4A, the first beam path 130-1 passes twice through the functionalized diffuser element 122-2 associated with the second optical channel. This is because the first functionalized diffuser element 122-1 is arranged in a reflection geometry in the first beam path 130-1, while the second functionalized diffuser element 122-2 is arranged in a transmission geometry in the second beam path 130-2. Furthermore, the first and second diffuser elements 122-1 are stacked. This means that the light traveling along beam path 130-1 is not, or only minimally, diffused by the functionalized diffuser element 122-2, and vice versa.

[0091] In FIG. 4A, the two functionalized diffuser elements 122-1 and 122-2 are shown.

[0092] Free-beam geometry illuminated. The functionalized diffuser element 122-1 is illuminated in reflection geometry from the beam path 130-1; the functionalized diffuser element 122-2 is illuminated in transmission geometry from the beam path 130-2. However, other variants are also conceivable, as illustrated, for example, in FIG. 4B. In the variant of FIG. 4B, the two functionalized diffuser elements 122-1, 122-2 (e.g., holographic diffuser elements) are illuminated in edge-illumination geometry and are formed in a common substrate 150. FIG. 5 shows yet another variant of the optical arrangement 91 with several diffuser elements 122-1, 122-2. In the variant of FIG. 5 are both the first functionalized diffuser element 122-1 and the second functionalized diffuser element 122-2 arranged in transmission geometry in the respective beam path 130-1 , 130-2.It would be conceivable that the two diffuser elements 122-1 , 122-2 are integrated in a common substrate (see FIG. 4B).

[0093] The light emitted by the first projection unit 121-1 along the first beam path 130-1 is not scattered by the second diffuser element 122-2. This is due to the functionalization of the second diffuser element 122-2. For example, the second functionalized diffuser element 122-2 can be wavelength-selective, such that the light emitted by the first projection unit 121-1 lies outside a wavelength range of light that is scattered by the second functionalized diffuser element 122-2. Besides such wavelength-based multiplexing, it would also be conceivable that the optical channels are multiplexed based on the polarization and / or angle of incidence of the respective light. Such multiplexing of light is made possible, in particular, by the use of holographic diffuser elements.

[0094] In the examples of FIG. 4A, FIG. 4B and FIG. 5, the two beam paths 130-1 , 130-2 (from the separate projection units 121-1 , 121-2) are combined by means of the diffuser elements 122-1 , 122-2.

[0095] The two diffuser elements 122-1, 122-2 are stacked apart from each other in FIGS. 4A, FIGS. 4B and FIG. 5; a corresponding gap 129 is illustrated in FIG. 4A. This gap 129 is dimensioned relative to the side length of the diffuser elements 122-1, 122-2, namely at approximately 15% of the side length. The gap 129 creates a distance 99 between the virtual images 96-1, 96-2; this allows a scene with a depth impression to be generated. A depth impression can also be achieved by curving the diffusing surface of a diffuser element.

[0096] FIGS. 6, 7A, and 7B illustrate variants of the HUD display system 90 and the optical arrangement 91, respectively, in which the respective functionalized diffuser element 122 is convexly or concavely curved. Such curvature gives the virtual image 96 depth (FIG. 6 and FIG. 7A) or can compensate for curvature of the windshield 190 (FIG. 7B). Besides convex or concave curvature, other curvature shapes are also conceivable, in particular freeform curvatures.

[0097] Another variant is shown in FIG. 7C. There, a tilt of the windshield 190 is compensated by a corresponding tilt of the diffuser element 122. As can be seen in FIG. 7C, the windshield 190 and the diffuser surface of the functionalized diffuser element 122 are tilted relative to each other (for example, by rotation about an axis of rotation parallel to the x-axis). As a result, the virtual image 96 does not exhibit a corresponding rotation when viewed from the eyebox 95. In principle, such a relative tilt of the diffuser surface with respect to the windshield 190 (or more generally, the deflection surface) can be a one-dimensional or a two-dimensional tilt.

[0098] FIG. 8 shows another variant of the HUD display system 90. FIG. 8 is a top view of the windshield 190 from the perspective of the vehicle's interior; that is, the inner surface 191 of the windshield 190 extends into the plane of the drawing. FIG. 8 shows that the two functionalized diffuser elements 122-1, 122-2 separate the beam paths 130-1, 130-2 by deflecting the corresponding beam paths 130-1, 130-2 differently. This allows two different eyeboxes 95-1, 95-2 to be operated. For example, eyebox 95-1 can be intended for the driver of the vehicle and eyebox 95-2 for a passenger. Also shown in FIG.As described above, light from the first optical channel can pass through the functionalized diffuser element 122-2 without being scattered because the light from the first optical channel has a wavelength and / or polarization to which the second holographic diffuser element 122-2 is not selective. This can be achieved in particular by using holographic diffuser elements.

[0099] Different eyeboxes can also be achieved with variants similar to FIG. 4A, FIG. 4B or FIG. 5, namely by having the different beam paths 130-1 , 130-2 have mutually opposed sources.

[0100] FIG. 9 illustrates a variant of the HUD display system 90 in which a microlens array 180 is provided. The microlens array 180 extends along the functionalized diffuser element 122. The microlens array 180 is arranged at a distance from the HOE of the functionalized diffuser element 122 that corresponds to a "focal length" of the HOE. In this case, the scattering characteristic of the HOE is configured to collect light. By means of the microlens array 180, it becomes possible to shift the virtual image 96 to infinity. This is evident in FIG. 9 because the rays of the beam path 130 run parallel in front of the eyebox 95.

[0101] Such a variant with a microlens array can be combined with other variants disclosed herein; in particular, multiple optical channels could be implemented by a stack of holographic diffuser elements with a common microlens array. This means that—for example, as shown in FIG. 4A—multiple holographic diffuser elements can be used, arranged offset from one another in the z-direction and extending along each other. Each of these holographic diffuser elements has a distinct scattering characteristic, so that the correspondingly scattered light is collected. A kind of "focal length" is thus defined. This focal length is different for the various holographic diffuser elements, corresponding to a distance in the z-direction between the holographic diffuser elements.This ensures that the microlens array is positioned at the "focal length" of each of the holographic diffuser elements. This allows the virtual image planes of all channels to be located at infinity.

[0102] FIG. 10 illustrates another variant of the HUD display system 90 or the optical arrangement 91. In the variant shown in FIG. 10, the optical arrangement 91 also includes a deflecting element 181, in this case a mirror 181. This mirror 181 deflects the beam path 130. The mirror 181 is arranged between the functionalized diffuser element 122 and the windshield 190. In particular, the mirror 181 is arranged with respect to the functionalized diffuser element 122 or the projection unit 121 such that the beam path 130 forms a loop. This allows the optical arrangement 91, according to the variant shown in FIG. 10, to be integrated into a particularly small installation space. For example, it would be conceivable that the mirror 181 is rotatable about an axis 182 (perpendicular to the drawing plane) (for example driven by a motor) in order to change or adjust the position of the eyebox 95.

[0103] Figure 11 illustrates the optical arrangement 91 according to the variant shown in Figure 10, and the installation space 405 is depicted. A beam trap 185 is also illustrated. The beam trap can capture stray light, such as that caused by unwanted Fresnel reflections or other reflections. Alternatively or additionally, it can prevent ambient light—e.g., from inside the vehicle—from entering the optical arrangement 91. The beam trap 185 can be configured as a microlouvered grating. Figure 11 also shows the projection distance 406 from the eyebox 95 to the virtual image 96. The projection distance 406 is particularly large due to the loop.

[0104] FIG. 12 – left – illustrates the scattering of an incident light ray at a scattering center; while FIG. 12 – right – shows the refraction of a light ray at an interface between two optical media with different refractive indices. In a holographic diffuser element, light is not scattered classically, but rather diffracted. However, the diffraction is designed in such a way that scattering centers are simulated in small areas (slightly larger than the wavelength of the light).

[0105] The preceding section illustrated aspects relating to a HUD display system 90 in which the windshield 190 implements a deflecting surface. These techniques can be used not only in connection with a HUD display system but also in connection with a display system for a digital instrument panel. In this case, the deflecting surface is no longer implemented by the windshield 190, but by a separate deflecting disc located in the area of ​​the dashboard. Otherwise, corresponding techniques, as explained in connection with the preceding figures, can also be used for such a display system for a digital instrument panel.

[0106] FIG. 13 illustrates a display system 890 for a digital instrument panel in the dashboard of a motor vehicle. The display system 890 is fundamentally configured according to the HUD display system 90, i.e., it includes the projection unit 121 and the functionalized diffuser element 122. In the example of the display system 890, however, the beam path is not deflected at the windshield 190; rather, a deflecting surface, or in particular a deflecting disc 820, is provided, which—from the driver's perspective—is located below the windshield in the area of ​​the dashboard. The dashboard forms a cavity 810 for this purpose (a section through the cavity is shown in FIG. 13). The cavity 810 is open towards the eyebox 95. The cavity 810 extends elongated in a direction perpendicular to the plane of the drawing (i.e., parallel to the y-axis). The deflecting disk 820 is arranged in cavity 810, which deflects the beam path towards the eyebox 95.The virtual image 96 is thus perceived from the eyebox 96 as floating freely within the interior space 811 formed by the cavity 810. For example, the cavity could have a darkening on its back side 812. In this case, the cavity is perceived as dark or black, and the virtual image 96 can be perceived as floating freely in this dark area with high brightness contrast.

[0107] It would also be conceivable that the deflecting disc 820 has a backside darkening.

[0108] While in the example of FIG. 13 the virtual image 96 is arranged in the interior 811 of the cavity 810, in other variants it would also be conceivable that the virtual image 96 - starting from the eyebox 95 - is arranged behind the back 812 of the cavity 810.

[0109] FIG. 14 shows a variant of the display system 890. In the variant shown in FIG. 14, the diffuser element 122 is not illuminated in transmission geometry, as in the variant shown in FIG. 13, but rather in reflection geometry (see, for example, FIG. 4A, diffuser element 122-1). The deflecting disk 820 is arranged between the projection unit 121 and the diffuser element 122; this means that the light beam originating from the projection unit 121 first passes through the deflecting disk 820 and then strikes the diffuser element 122. In the scenario shown in FIG. 14, a one-way mirror is mounted on the front (i.e., the side facing the eyebox 95) of the deflecting surface 820 (for example, a glass substrate). The one-way mirror is designed to reflect (significantly) only when the light strikes it from the front (i.e., coming from the diffuser element 122). For this purpose, the one-way mirror can, for example, be...It can be designed as a layer stack comprising an antireflective coating on the side facing away from the eyebox 95 and a metallic layer on the side facing the eyebox 95. Instead of a one-way mirror, a holographic optical element that simulates a one-way mirror through diffraction effects would also be conceivable. If such a functional reflective element with an asymmetric reflectance is used, the light beam, originating from the projection unit 121, can first pass through the deflecting disk 820 and the reflective element without significant losses before being deflected by the diffuser element 122 onto the reflective element.Reflectance is understood here as the proportion of light that is deflected by the functional optical element towards the eyebox; and it encompasses not only reflection effects (for example, in a one-way mirror with an anti-reflective coating) but also diffraction effects, for example, when a holographic optical element is used.

[0110] If no functional reflective element with an asymmetric reflectance is used, but only the deflecting disk (e.g., designed as a simple mirror), losses occur – this can also be acceptable. The variant in FIG. 14, for example, has a particularly high degree of integration compared to the variant in FIG. 13, meaning that the various elements can be integrated very compactly. The required installation space is particularly small.

[0111] FIG. 15 shows another variant of the display system 890. The variant in FIG. 15 is essentially the same as the variant in FIG. 14. In the example of FIG. 15, the diffuser element 122 is curved (see also FIG. 6). As a result, the virtual image 96 also has a curvature. This creates a depth impression.

[0112] FIG. 16 illustrates another variant of the 890 display system. The variant from

[0113] FIG. 16 is essentially the same as the variant shown in FIG. 14. In the variant shown in FIG. 16, two projection units 121-1 and 121-2 are present. These two projection units are arranged on opposite sides of the cavity 810. Projection unit 121-2 corresponds to projection unit 121 from the variant shown in FIG. 14. Projection unit 121-1 illuminates another diffuser element 122-1, which in the example shown in FIG. 16 is flat but tilted relative to diffuser element 122-2, which is illuminated by projection unit 121-2. This tilt also causes the corresponding virtual images 96-1 and 96-2 to be tilted relative to each other.By having the diffuser elements 122-1 , 122-3 designed holographically, selectivity can be achieved on the wavelength range of the light of the respective optical channel generated by the corresponding projection unit 121 -1 , 122-2 (see also FIG. 4B).

[0114] Due to the use of defined scattering characteristics for the diffuser element, it is generally possible for the projection unit—as shown in FIG. 16 for projection unit 121-1—to be arranged on the underside of cavity 810. The use of the diffuser element prevents light from the projection unit, thus arranged on the underside of cavity 810, from directly reaching the viewer's eye. In reference implementations that do not use a diffuser element (explained later in FIG. 19), corresponding screens cannot be arranged on the underside of the cavity without disturbing scattered light being perceived by the viewer.

[0115] Several variations of the corresponding display systems 890 are conceivable. For example, a variation could be conceivable in which one or both of the diffuser elements 1022-1, 122-2 are curved. A curvature can create a depth impression. This was already discussed above in connection with FIG. 7A.

[0116] FIG. 17 illustrates another variant of the display system 890 from FIG. 13. In FIG.

[0117] Figure 17 shows the display system 890 extended by light-emitting diodes 819, which are arranged in the area of ​​the rear side 812 of the cavity 810, that is, behind the deflecting disk 820, starting from the eyebox 95. The light-emitting diodes 819 generate a quasi-coherent light source for illuminating a HOE 817, which is attached to the deflecting disk 820. For example, the deflecting disk 820 and the HOE 817 could be formed on a common substrate. By illuminating the HOE 817, a hologram 818—here a free-floating 3D information element or other "image"—is reconstructed, which in the example of Figure 17 is arranged between the deflecting disk 820 and the eyebox 95. However, it would also be conceivable in principle for the hologram 818 to be arranged in the interior 811 of the cavity 810. Depending on the relative positioning of hologram 818 in relation to HOE 817, hologram 818 is reconstructed in transmission geometry or in reflection geometry.

[0118] Hologram 818, for example, can be selectively switched on or off by turning its backlight on or off. It would also be conceivable to stack several HOE units on the deflecting disk 820. In this way, multiple holograms could be selectively switched on or off, for example, by separating them using different wavelengths, polarizations, or reconstruction angles. This would allow for the provision of semi-dynamic information in the form of multiple holograms, activated, for example, according to specific situations.

[0119] All variants of the display system 890, as described above, have the advantage that a large virtual image 96 can be generated. In other words, the extent of the virtual image 96 along the y-axis—that is, along the longitudinal axis of the cavity—can be particularly large. This allows a great deal of information to be displayed on the digital instrument panel, such as large map sections or a multimodal graphical user interface. Details regarding this advantage of a large virtual image 96 are explained below. In particular, a virtual image 96 can be generated that has a large extent, for example, along the y-direction, that is, a large extent in the longitudinal direction of the cavity 810. This aspect is illustrated in FIG. 18.

[0120] Figure 18 shows a top view of the display system 890. The diffuser element 122 and the deflecting disk 820 extend longitudinally (parallel to the y-axis) within the cavity 810, which extends along this longitudinal direction. The projection unit 121 is located in a central area of ​​the cavity 810 and illuminates the entire diffuser element 122 and the entire deflecting disk 820, respectively. Nevertheless, the eyebox 95 is formed. This is achieved by scattering lobes of the functionalized diffuser element 122, each oriented towards the eyebox 95 (the orientation of the scattering lobes is illustrated by the dashed arrows in Figure 18). See also Figure 2, where a corresponding variation in the orientation of the scattering lobes 312 as a function of the lateral position along the x-axis is shown. A reference implementation of a comparable display system 990 is shown in Figure 2. 19 shown.There, several LCD displays 921-1, 921-2, 921-3 are used to illuminate a corresponding section 829-1, 829-2, 829-3 of the deflecting disk 820. In the reference implementation shown in FIG. 19, no diffuser element is used. Therefore, an eyebox cannot be formed. This necessitates having multiple LCD displays 921-1, 921-2, 921-3 for the different sections 829-1, 829-2, 829-3 of the deflecting disk 820. This requires a relatively large amount of installation space and is complex. Furthermore, a significant amount of light is lost, as it does not reach the viewer's eyes. Consequently, energy consumption increases compared to the variant shown in FIG. 18.

[0121] FIG. 20 shows a variant of the projection unit 121; in this variant, there is no spacing between the functionalized diffuser element 122 and the projection unit 121 – rather, the diffuser element 122 is integrated into the projection unit 121. In various variants, it would generally be conceivable for the functionalized diffuser element to be attached to or integrated into the projection unit. For example, the functionalized diffuser element 122 could be arranged as a location-dependent microstructure on a liquid crystal plane 121-2, which is illuminated in a backside geometry by a light source 121-1, or more generally, extend along this plane (see FIG. 20). The information related to FIG.The 20 aspects explained regarding the projection unit 121 can be combined with the various other aspects described herein (for example, with the design of the functionalized diffuser element as HOE, the curvature of the diffuser surface, etc.).

[0122] Naturally, the features of the embodiments and aspects of the invention described above can be combined with one another. In particular, the features can be used not only in the combinations described, but also in other combinations or individually, without departing from the scope of the invention. For example, techniques have been disclosed above in which a functionalized diffuser element is used to define an eyebox for a HUD. In particular, it has been explained how an HOE can be used to implement the functionalized diffuser element. In one variation, a projection unit projects multiple images onto an HOE, which replicates a microlens array. This means that the HOE replicates the refraction of light rays at the microlenses of the microlens array.Each microlens replicated by the HOE is assigned a perspective of a 3D scene (also referred to as elemental images); this enables a light field projection of the 3D image. In this way, a 3D display for a HUD, for example in a vehicle, can be made possible.

Claims

PATENT CLAIMS 1. Optical arrangement (91) for a display system (90, 890) on a deflecting surface (190, 820), wherein the optical arrangement (91) comprises: - at least one projection unit (121 , 121-1 , 121-2) configured to project at least one image onto at least one functionalized diffuser element (122, 122-1 , 122-2) by emitting light along at least one beam path (130, 130-1 , 130-2), and - the at least one functionalized diffuser element (122, 122-1 , 122-2) which is arranged along the at least one beam path (130, 130-1 , 130-2) and which is configured to diffuse the at least one beam path (130, 130-1 , 130-2) in such a way that a virtual image (96) of the projected at least one image is perceptible in at least one eyebox (95) of the display system (90, 890).

2. Optical arrangement (91) according to claim 1, wherein each of the at least one functionalized diffuser element (122, 122-1, 122-2) is formed in a one-piece substrate.

3. Optical arrangement according to claim 1 or 2, wherein the at least one functionalized diffuser element (122, 122-1 , 122- 2) is configured such that a scattering characteristic has a dependence on a position along the surface of the functionalized diffuser element and / or a wavelength of the light and / or a polarization of the light.

4. Optical arrangement (91) according to one of the preceding claims, wherein the at least one functionalized diffuser element (122, 122-1 , 122- 2) comprises at least one holographic diffuser element (122, 122-1 , 122-2).

5. Optical arrangement (91) according to claim 4, wherein the holographic diffuser element (122, 122-1 , 122-2) is formed in one or more substrates.

6. Optical arrangement (91) according to claim 4 or 5, wherein the at least one holographic diffuser element (122, 122-1 , 122- 2) comprises several holographic diffuser elements (122, 122-1 , 122-2) which are designed to diffract light with different wavelengths and / or different angles of incidence and / or different polarizations.

7. Optical arrangement (91) according to claim 6, wherein the multiple holographic diffuser elements (122, 122-1, 122-2) are arranged in a stacked configuration.

8. Optical arrangement (91) according to claim 7, wherein the multiple holographic diffuser elements (122, 122-1 , 122-2) are stacked spaced apart from each other.

9. Optical arrangement (91) according to claim 7, wherein a gap (129) between the multiple holographic diffuser elements (122, 122-1 , 122-2) is not less than 10% of a side length of the multiple holographic elements (122, 122-1 , 122-2).

10. Optical arrangement (91) according to claim 6, wherein the multiple holographic diffuser elements (122, 122-1, 122-2) are arranged tilted relative to each other.

11. Optical arrangement (91) according to claim 6 or 10, wherein a first of the several holographic diffuser elements (122, 122-1 , 122-2) is planar, wherein a second of the several holographic diffuser elements (122, 122-1 , 122-2) is curved.

12. Optical arrangement (91) according to one of claims 6 to 11, wherein the multiple holographic diffuser elements (122, 122-1, 122-2) are formed in a common substrate (150).

13. Optical arrangement (91) according to any one of claims 6 to 12, wherein the at least one holographic diffuser element (122, 122-1 , 122- 2) is arranged in edge illumination geometry in the at least one beam path (130, 130-1 , 130-2).

14. Optical arrangement (91) according to one of the preceding claims, wherein the at least one functionalized diffuser element (122, 122-1, 122- 2) comprising several functionalized diffuser elements (122, 122-1 , 122-2) wherein the several functionalized diffuser elements (122, 122-1 , 122-2) are configured to separate or combine two or more beam paths (130, 130-1 , 130-2).

15. Optical arrangement (91) according to one of the preceding claims, wherein the at least one functionalized diffuser element (122, 122-1, 122- 2) is further set up to reduce divergence of at least one beam path.

16. Optical arrangement (91) according to one of the preceding claims, wherein the at least one functionalized diffuser element (122, 122-1, 122- 2) is further set up to redirect at least one beam path (130, 130-1 , 130-2).

17. Optical arrangement (91) according to one of the preceding claims, wherein at least one of the at least one diffuser element (122, 122-1 , 122-2) is arranged in transmission geometry in the beam path (130, 130-1 , 130-2).

18. Optical arrangement (91) according to one of the preceding claims, wherein at least one of the at least one diffuser element (122, 122-1 , 122-2) is arranged in reflection geometry in the beam path (130, 130-1 , 130-2).

19. Optical arrangement (91) according to one of the preceding claims, wherein the optical arrangement (91) further comprises: - a deflecting element arranged along the at least one beam path downstream from the at least one diffuser element (122, 122-1 , 122-2) and configured to deflect the at least one beam path.

20. Optical arrangement (91) according to claim 19, wherein the deflecting element is arranged such that the at least one beam path forms a loop.

21. Optical arrangement (91) according to one of the preceding claims, wherein the optical arrangement (91) further comprises: - a microlens array (180) extending along the at least one functionalized diffuser element (122, 122-1 , 122-2).

22. Optical arrangement (91) according to claim 21, wherein the at least one functionalized diffuser element (122, 122-1, 122-2) comprises at least one holographic diffuser element (122, 122-1, 122-2) which has a holographic-optical element which defines a focal length for the light, wherein the microlens array (180) is arranged at a distance to the holographic-optical element which corresponds to the focal length.

23. Optical arrangement (91) according to one of the preceding claims, wherein at least one of the at least one functionalized Diffuser elements (122, 122-1 , 122-2) have a curved diffuser surface.

24. Display system (90, 890), which includes: - the optical arrangement (91) according to one of the preceding claims, and - the deflection area (190, 820).

25. Display system (890) according to claim 24, wherein the at least one beam path first strikes the deflecting surface (820) from a rear side and passes through it without deflection before the beam path strikes the at least one functionalized diffuser element.

26. Display system (90, 890) according to claim 24 or 25, wherein the deflecting surface (820) comprises a functional reflective element with an asymmetric reflectance.

27. Display system (90, 890) according to one of claims 24 to 26, wherein the at least one beam path is reflected at a first side of the deflecting surface (190, 820), wherein the display system (90, 890) further comprises a backside darkening (195) at a second side of the deflecting surface (190, 820).

28. Display system (890) according to any one of claims 24 to 27, further comprising: - a cavity (810) extending along a longitudinal direction, wherein the deflecting surface is designed as an elongated deflecting disk (820) which extends in the cavity (810) along the longitudinal direction (y).

29. Display system (890) according to claim 28, wherein the cavity is formed from a dashboard of a vehicle.

30. Display system (890) according to claim 28 or 29, wherein the cavity (810) has a backside darkening.

31. Display system (890) according to one of claims 28 to 30, further comprising: - a light source (819) arranged on a rear side (812) of the cavity (810), and - a holographic-optical element (817) extending along the deflecting surface (820) and configured to reconstruct a hologram (818) based on illumination by the light source.

32. Display system (90, 890) according to one of claims 24 to 31, wherein the deflecting surface and a diffuser surface of the at least one functionalized diffuser element are tilted relative to each other.

33. Display system (90, 890) according to one of claims 24 to 32, wherein the deflecting surface and a diffuser surface of the at least one functionalized diffuser element have different curvatures.

34. Display system (90, 890) according to claim 33, wherein the diffuser surface has a convex curvature, wherein the deflecting surface has a convex curvature, or wherein the diffuser surface has a concave curvature, wherein the deflecting surface has a concave curvature.

Images