Projection unit for a field-of-view display device used in a vehicle

Abstract

This invention relates to a projection unit for a field-of-view display device for generating a virtual display image in the field of view of a user, particularly an occupant. The projection unit includes: a projector for generating a projection beam including display content; and a combination thereof disposed in its optical path, comprising a holographic diffuser and a refractive element extending behind the back side of the diffuser, wherein the projector, the holographic diffuser, and the refractive element are configured and arranged such that: the projection beam first enters the front side of the holographic diffuser facing the projector and is transmitted by the diffuser to the refractive element, and the projection beam is reflected back by the refractive element to the back side of the holographic diffuser; wherein the holographic diffuser is configured to be a transmissive diffuser with predetermined directional selectivity and / or scattering characteristics for the projection beam incident from the back side.

Description

Technical Field

[0001] This invention relates to a projection unit for a field-of-view display device, intended for use in land, air, or water vehicles, particularly in motor vehicles, wherein a virtual display image is generated in the occupant's field of vision by reflection of a projection beam onto a transparent projection glass, such as the windshield of the vehicle. The invention also relates to a corresponding field-of-view display device and a vehicle equipped with it. Background Technology

[0002] A head-up display (HUD) is a device used in motor vehicles to display information, such as instructions on speed limits or other navigation and vehicle operation tips, superimposed on a virtual image of the actual environment in front of the vehicle as observed by the driver. For this purpose, a head-up display typically includes a projection unit housed in the dashboard that generates a projection beam containing the desired display content and projects it onto the vehicle's windshield or, additionally, a transparent composite glass panel in front of the windshield, which reflects the projection beam back to the driver.

[0003] As a picture generating unit (PGU) used to generate the display content to be transmitted by the projection beam, a liquid crystal display (LCD) with an LED backlight is typically used in the projection unit of a conventional head-up display. However, this type of PGU is difficult to scale up for larger head-up displays, for example, those needed to extend the field of view that can be covered by a virtual display image, such as for Augmented Reality (AR) displays oriented on contact simulations of actual environmental objects.

[0004] To address this problem, it is known to use an imager instead of an LCD, in which a real image is generated, similar to a screen, on a transmissive or reflective diffuser. This diffuser is configured, for example, with a suitably structured surface or scattering centers distributed throughout its volume, to diffusely scatter the light projected onto it. The image is projected onto the diffuser, for example, using a DLP chip (Digital Light Processing, registered trademark) or a MEMS-based laser-beam-scanner. Such a configuration is significantly more efficient and thermally stable than an LCD-PGU, and thus easier to expand.

[0005] As in Figure 1 As shown in the diagram (further explained below), a known disadvantage of such a diffuser-based PGU compared to a conventional LCD-PGU is the potential loss of contrast on the diffuser during sunlight exposure due to sunlight reaching the projection unit from the outside and being scattered by the diffuser. In unfavorable diffuser designs (e.g., Lambert designs), the brightness of the scattered sunlight can, in the worst case, even exceed the brightness of the HUD image, thereby posing a safety hazard because the driver's view of the road may be überblenden. In contrast, for LCD-based projection units, an effective measure against interference from solar reflections directed towards the user is known: tilting the smooth, specularly reflective LCD surface toward the optical axis of the projection unit so as to deflect interfering sunlight from the optical path of the projection beam and, for example, into a light trap.

[0006] As a possible solution for dealing with interfering solar reflections in diffuser-based imagers, a so-called diffuser hologram is integrated into the projection unit of a head-up display instead of a conventional diffuser that includes a structured surface for diffuse scattering or scattering centers distributed in a volume. With the diffuser hologram, the incident and scattered light can be modulated or controlled not only wavelength-selectively but also direction-selectively.

[0007] For example, DE 10 2012 219 723 A1 discloses a field-of-view display instrument for projecting graphic information for an observer onto an eye region surface (eyebox) of the instrument. The instrument has a projector for providing graphic information along the optical axis of the instrument and a projection surface unit for converting the graphic information into a real image. This projection surface unit is disposed along the optical axis between the projector and the image output unit of the instrument and has or is implemented as a volume hologram, which includes scattering characteristics of the graphic information directed toward the eye region surface. When used in a vehicle, projection optics, particularly concave mirrors, are further disposed along the optical axis between the projection surface unit and the image output unit to amplify the image, directing it toward the windshield of the vehicle, which acts as a reflective surface, and adapting it to the eye region surface.

[0008] Specifically, in DE 10 2012 219 723 A1, the projection surface unit can be implemented in a transmitted light configuration, wherein the projector is positioned on the side opposite to its image output section and the volume hologram functions as a frosted glass with special transmission characteristics. Alternatively, to reduce the required structural space, the projection surface unit can also be implemented in a reflected light configuration, wherein the projector is pointed towards its side facing the image output section and the volume hologram functions as an ideal diffuser with special transmission characteristics.

[0009] A potential drawback of this technology is that the directional selectivity (reflected light configuration) of the diffuser hologram used for reflection cannot be adjusted as precisely as in the diffuser hologram used for transmission (transmitted light configuration), and despite this, backscattering of sunlight may still occur. Furthermore, projection units that include diffuser holograms for transmission typically require significantly larger structural space, which is often severely limited, especially in motor vehicles. Summary of the Invention

[0010] The object of the present invention is to provide an alternative and / or particularly improved projection unit for improving the visibility of virtual display images and / or spatial integration in a vehicle, the projection unit comprising an imager with a holographic diffuser, and to provide a field-of-view display device comprising such a projection unit and a corresponding vehicle, particularly a motor vehicle.

[0011] The disclosure of this invention

[0012] This task is solved by a projection unit according to the invention, a field-of-view display device according to the invention, and a corresponding transport vehicle. All further features and functions described herein for the projection unit also apply to the field-of-view display device and the transport vehicle, and vice versa.

[0013] According to the first aspect, a projection unit is specified for a field-of-view display device, such as a head-up display (HUD), particularly designed for use in a vehicle. The vehicle can be any land, air, or water vehicle, but particularly a motor vehicle. The projection unit is configured to generate a projection beam carrying desired display content and project it onto a projection glass, which is to be placed or placed outside the projection unit, is reflective on the user side, and is transparent on the back side, particularly the windshield of the vehicle, to generate a virtual display image in the field of view of the user, particularly the driver.

[0014] The projection unit here includes: a projector for imaging to generate a projection beam with desired display content; and a combination of a holographic diffuser and a refractive element extending on or behind the back side of the generated projection beam, disposed in the optical path of the generated projection beam, the refractive element being particularly configured as a plane mirror. The projector, holographic diffuser, and refractive element are configured and arranged such that the generated projection beam first incident on the front side of the holographic diffuser facing the projector for imaging and—particularly with as little alteration as possible—transmitted by the diffuser to the refractive element, the projection beam being reflected back by the refractive element, particularly again substantially without loss and / or with surface coverage, to the back side of the holographic diffuser. The holographic diffuser is configured for the projection beam incident from the back side as a transmissive diffuser having predetermined directional selectivity and / or scattering characteristics.

[0015] The refractive element can be configured in any suitable manner to reflect the projected beam incident upon it toward the back side of the holographic diffuser (and thereby for the refractive path) as well as possible. In addition to conventional mirrors, such as those comprising a metallic mirror surface, the refractive element can alternatively, and particularly also, be configured as a holographic mirror with suitable reflective properties, for example, to achieve a reflection angle different from the angle of incidence and / or to limit the wavelength selectivity of the projected light used, in order to additionally suppress external light, such as the aforementioned interfering solar reflection. Instead of a plane mirror, any other optical component with reflective properties suitable for the functionality described herein can also be used as the refractive element, such as a reflective polarizer or the like.

[0016] In addition to the directional selectivity for the projection beam incident from the back side, the holographic diffuser can also be configured to have suitable angular selectivity for light incident from the front and / or from the back side and / or suitable directional selectivity for light to be transmitted from the front side. This can again, in particular, help to filter external light out of the optical path of the projection unit. Furthermore, light traps for external light can also be provided in suitable locations in a manner known per se.

[0017] One concept of this arrangement is to combine a holographic diffuser designed for transmission, functioning as an imager, within the projection unit with a refractive element positioned close to or directly behind the holographic diffuser in the optical path of the projection light—especially covering the cross-section of the beam—in order to achieve a space saving that has so far only been known for reflective diffusers. Thus, this arrangement allows for the simultaneous utilization of all the advantages of a holographic diffuser designed for both transmission and reflection.

[0018] A significant advantage of holographic diffusers designed to have predetermined directional selectivity or scattering characteristics in transmission compared to reflective holographic diffusers is that the angle range around the diffuser's surface normal can be selectively adjusted not only for projection light entering from the back side but also for projection light exiting from the front side or being scattered. This angle range can, in principle, be arbitrarily close to or concentrated around the surface normal. This enables particularly high optical quality of the projection unit by redirecting, uniformly distributing, or concentrating the available light (projection light) onto the eyebox (i.e., the surface area set for the user's eye, perpendicular to the propagation direction of the projection beam), from which a virtual display image can be seen. However, for the same reason, using a transmissive holographic diffuser also allows for particularly simple and effective measures against interfering back reflections from sunlight or other external light, such as specular reflections at a suitable tilted positioning angle relative to the optical axis, including, if necessary, a counter-positioned light trap.

[0019] In particular, the directional selectivity of the projection light can be precisely adjusted, in principle, according to the requirements of a specific application, using the inherent construction of the projection unit. Furthermore, this projection unit can reliably and completely suppress backscattering of possible external light interference, such as sunlight, known to conventional imagers in the form of conventional diffusers or reflective holographic diffusers, by means of a suitable structure and orientation on the front side of the holographic diffuser and / or by means of suitable directional and / or wavelength selectivity of the holographic structure for the front-incident light implemented therein. All of this results in a reduction of structural space compared to conventional arrangements that include transmissive diffusers, while simultaneously leading to improved contrast for the user's virtual display image.

[0020] The holographic diffuser can, for example, be configured as a thin, particularly planar sheet or film made of a suitable material (typically a polymer), the sheet or film comprising a holographic structure housed therein, particularly a so-called diffuser hologram of the type mentioned earlier. In particular, the holographic structure can be a volumetric hologram. The aforementioned sheet or film can be attached to the holographic structure, having additional functional layers, such as one or more protective layers made of plastic or glass, which in particular can prevent further interference with the projected beam and / or suppress external light.

[0021] In the assembled field-of-view display device, the projection glass, which extends in the optical path of the projection beam output by the projection unit relative to the projection unit, can be formed in a manner known per se, for example, by means of the windshield of a vehicle or by means of a composite glass that is also reflective on the user side and transparent on the back side, located inside the vehicle in front of the windshield.

[0022] The projector for imaging can, in principle, be any device configured to generate a beam of projection rays carrying the desired display content and project it onto a holographic diffuser. In particular, the projector can be a MEMS-based laser scanner with one or three background colors, configured to scan a surface in front of the holographic diffuser determined by the initial light incidence. Alternatively, the projector may also comprise a digitally manipulated array of micromirrors including a separate projection light source (DLP, Digital Light Processing, registered trademark).

[0023] In particular, the configuration and arrangement of the projector for imaging, the holographic diffuser, and the refractive element can be such that the generated projection beam first enters the front side of the holographic diffuser facing the projector for imaging, and is transmitted through the holographic diffuser substantially unaltered and / or without loss towards the refractive element. This can particularly contribute to improved visibility of the virtual display image for the user, such as increased contrast.

[0024] In particular, the configuration and arrangement of the projector for imaging, the holographic diffuser, and the refractive element can be such that the holographic diffuser forms a projection screen for the projection beam that enters from the back side and exits from the front side, and the real image of the displayed content is generated on or in the projection screen in the manner mentioned above.

[0025] In a particular configuration, the predetermined directional selectivity of the holographic diffuser can be designed for the aforementioned projection beam incident from the back side to ensure maximum and / or substantially uniform projection light intensity within a predetermined beam cross-section and / or minimum and / or imperceptible projection light intensity outside that beam cross-section, which fills the eyebox or the virtual display image that can be generated as determined by the user's eye. In particular, the aforementioned maximum projection light intensity, for example, substantially constant within the predetermined beam cross-section, can provide an intermediate or main beam for the projection unit or field-of-view display device, guided from the center, for example, the front side of the surface of the holographic diffuser that functions as a projection screen, to the center of the eyebox or the virtual display image that can be generated. This predetermined directional selectivity can be defined, for example, by a predetermined range of incident angles on the back side and / or a predetermined range of scattering angles on the front side, which can vary, particularly in relation to position, within the back or front side of the holographic diffuser. This can be performed, particularly in a manner known for the transmissive diffuser hologram itself.

[0026] In one particular configuration, the refractive elements can extend behind the back side of the holographic diffuser at predetermined, constant intervals, particularly a few micrometers less than one millimeter, a few millimeters less than one centimeter, or even a few centimeters, especially no more than 1, 2, or 3 centimeters. This allows for a particularly space-saving arrangement.

[0027] In particular, however not mandatory, the projection unit may have one or more additional optical elements, such as a concave mirror or other optical projection element and / or other refractive elements for refracting the projection beam, in the optical path of the projection beam after the holographic diffuser.

[0028] According to another aspect, a field-of-view display device, particularly for use in a vehicle, is specified. This device has a projection unit of the type described herein and a projection glass, particularly the windshield of the vehicle, that is reflected on the user side and is transparent on the back side, arranged in the optical path of the projection beam output from the projection unit. The vehicle can be any land, air, or water transport, but particularly a motor vehicle. Here, the projection unit and the projection glass are configured and arranged relative to each other such that the projection beam output from the projection unit during operation is incident on the projection glass and reflected by the projection glass to the user, particularly the driver of the vehicle, thereby generating a virtual display image in the user's field of vision behind the projection glass.

[0029] According to another aspect, a means of transport, particularly a motor vehicle or any other land, air, or water transport, is specified. The means of transport herein includes: a windshield and an instrument panel, the upper side of which extends below the windshield; and a field-of-view display device of the type described herein, the projection glass of which is formed through the windshield and the projection unit of which is disposed in the instrument panel, so as to insert a virtual display image into the field of view of the occupant, particularly the driver, when looking through the windshield. The upper side of the instrument panel may, in a manner known per se, have an aperture for the projection beam and further mechanically and optically cover and protect the projection unit and its optics outwardly. Attached Figure Description

[0030] Brief description of the attached figures

[0031] The foregoing aspects of the invention, its embodiments, and particular constructions are then further explained with the aid of examples shown in the accompanying drawings. The drawings are purely schematic and should not, in particular, be construed as faithful to scale. The same reference numerals denote the same elements or elements corresponding to each other in their function. Drawings:

[0032] Figure 1 A schematic side cross-sectional view of a conventional field-of-view display device including an imager having a conventional diffuser for reflection is shown.

[0033] Figure 2 A schematic side cross-sectional view showing a field of vision display device of the type described herein in a motor vehicle; and

[0034] Figure 3 Show Figure 2 The magnified portion further illustrates a combination comprising a holographic diffuser that transmits light and a refractive element extending behind the back side of the diffuser, the holographic diffuser being transparent to the projected light on the front side and having predetermined directional selectivity and / or scattering characteristics on the back side. Detailed Implementation

[0035] Explanation of each implementation form

[0036] All the different embodiments, variations, and special design features of the projection unit, field display device, and transport vehicle mentioned above in the specification according to the foregoing aspects of the present invention can be implemented... Figure 2 and 3 The examples shown are implemented in [the document]. Therefore, they are not all repeated here. The same applies accordingly to the conceptual definitions already given above and regarding [the implementation of...]. Figure 2 Or the function of the various features shown in section 3.

[0037] Figure 1 First, a strongly simplified schematic vertical cross-sectional view shows the aforementioned field-of-view display device 100, known from the prior art, configured as a head-up display of a vehicle 200, and used to illustrate the aforementioned problem of interfering sunlight reflection when using a conventional diffuser 300 configured to reflect light in place of a liquid crystal display (LCD) for imaging.

[0038] The field-of-view display device 100 includes a projection glass 400 and a projection unit 700 disposed below it in the dashboard 600 of the vehicle 200, the projection glass being in... Figure 1 The windshield 500 of the vehicle 200 is a portion thereof. The projection unit 700 includes an imaging projector 800 for generating a projection beam L with the desired display content and a conventional diffuser 300 designed for reflection disposed in the optical path of the generated projection beam L. The diffuser thus constitutes a backscatterer for the diffusion of light incident on it at the front, for example, as a Lambertian radiator.

[0039] Here, on the front side 300a of the conventional diffuser 300, a real image is generated, for example, by scanning the front side by a projector 800 configured as a laser scanner (MEMS) and then projected onto a projection glass 400 by means of a concave mirror 900 designed for optical magnification and further adaptation. The image is reflected by the projection glass to an eye box 1000 determined for the occupant (not shown) so as to generate a virtual display image V inserted into the field of vision at a distance in front of the vehicle 200.

[0040] As in Figure 1 As shown, undesirable backscattering of sunlight S from the outside into the projection unit 700 can occur on a conventional diffuser 300 when sunlight shines on it. This is due to the sunlight S reaching the projection unit 700 from the outside. In unfavorable diffuser designs, such as Lambertian designs (in... Figure 1 The scattered sunlight S, indicated by arrows emanating from the front 300a in all directions, may be even brighter than the virtual display image V in the worst case, thus posing a safety risk by, for example, fading the driver's view of the road.

[0041] Figure 2 A strongly simplified schematic vertical cross-sectional view shows a field-of-view display device 1 of the type described herein, which includes a projection unit 7 according to the first aspect of the invention described above in a means of transport 2 (in the example, a motor vehicle), using which the field-of-view display device... Figure 1 The solar reflection interference represented in the figure can be reliably suppressed, and the contrast and brightness of the virtual display image V can be significantly improved, without needing to compare it with [other images]. Figure 1 This significantly increases the structural space required for the projection unit 7. The field of view display device 1 is configured here as a head-up display, purely by way of example.

[0042] In this example, the field of view display device 1 is similar to Figure 1 The vehicle 2 has a projection glass 4 and a projection unit 7 disposed below it in the dashboard 6 of the vehicle 2. The projection glass constitutes a section of the windshield 5 of the vehicle 2. The projection unit 7 has a projector 8 for imaging to generate a projection beam L with the desired display content. The projector may be configured, for example, as a DLP chip (DLP, Digital Light Processing, registered trademark) or a laser scanner based on MEMS technology.

[0043] according to Figure 2 The type of projection unit 7 described here and Figure 1 The decisive structural difference of the known arrangement is that, instead of a conventional diffuser 300, a combination of a holographic diffuser 3 and a refractive element 11 (in the example, a plane mirror) extending behind the back side 3b of the diffuser is provided in the optical path of the projection beam L generated by the projector 8. Figure 3 In China, with Figure 2 The corresponding enlarged portion is shown below:

[0044] As in Figure 3 As particularly evident in the diagram, the configuration and arrangement of the projector 8, the holographic diffuser 3, and the refractive element 11 are such that the generated projection beam L first enters the front side 3a of the holographic diffuser 3 facing the projector 8 and is transmitted through the diffuser to the refractive element 11 substantially unchanged. Subsequently, in this example, the projection beam L is again reflected back by the refractive element 11 substantially without loss and substantially covering the back side 3b to the back side 3b of the holographic diffuser 3. The holographic diffuser 3 is configured as a transmission diffuser with predetermined direction selectivity and scattering characteristics for the projection beam L incident from the back side.

[0045] The projected beam L1, originating from the front side 3a of the holographic diffuser 3 according to its direction selectivity and scattering characteristics, ... Figure 2 Then, purely exemplarily (similar) Figure 1The projection beam is reflected by a concave mirror 9 designed for optical magnification and further adaptation, and projected onto a projection glass 4. The projection beam is then reflected by the projection glass to an eyebox 10 defined for the occupant (not shown). This generates a virtual display image V in the occupant's field of vision, spaced some distance in front of the vehicle 2.

[0046] Here, the eyebox 10 is defined as a two-dimensional surface perpendicular to the direction of light propagation, located inside the vehicle in front of the windshield 5, through which the virtual display image V is visible to the occupant, such as the driver. Because the projection glass 4 is at least partially transparent to ambient light on its back side, the virtual display image V generated behind it is superimposed on the actual environment observed by the occupant in front of the vehicle 2 when viewed through the windshield 5.

[0047] The holographic diffuser 3 is in accordance with Figure 2 and 3 In this example, it is configured as a planar sheet made of a suitable material, such as a polymer, the sheet including a hologram structure therein as a volume hologram (in this example, a diffuser hologram with the predetermined direction selectivity and scattering characteristics described above).

[0048] In particular, the predetermined directional selectivity of the holographic diffuser 3 can be applied according to... Figure 2 and 3 The projection beam L, which is incident from the back side, is designed to: ensure the maximum and / or substantially uniform projection light intensity within a predetermined beam cross-section and the minimum or imperceptible projection light intensity outside that beam cross-section, which fills the eyebox 10 or the virtual display image V that can be generated.

[0049] exist Figure 2 and 3 In the particular configuration shown, the refractive element 11 extends behind the back side 3b of the holographic diffuser 3 at a predetermined constant distance D, such distance being, for example, a few micrometers less than one millimeter, a few millimeters less than one centimeter, or even a few centimeters. This allows for the best possible optical design of the projection unit 7 regarding the brightness and contrast of the virtual display image V, while also achieving a space-saving arrangement, which is superior to arrangements made according to... Figure 1 The conventional design requires almost no additional space in the dashboard 6 of the vehicle 2.

[0050] List of reference numerals

[0051] 1. 100° field of view display device

[0052] 2. 200 transport vehicles

[0053] 300 Traditional diffusers (i.e., without holograms)

[0054] 3 Holographic Diffuser

[0055] The front side of the 3a holographic diffuser

[0056] The back side of the 3b holographic diffuser

[0057] 4. 400 projection glass

[0058] 5.500 windshield

[0059] 6. 600 dashboard

[0060] 7.700 projection units

[0061] 8. 800 projector

[0062] 9. 900 concave mirror

[0063] 10, 1000 eye boxes

[0064] 11 refractive elements

[0065] L is the projection beam generated by the projector performing the imaging.

[0066] L1 is the projection beam emitted from the front of the holographic diffuser and output by the projection unit.

[0067] V virtual display image

[0068] S Sunshine

[0069] D is a predetermined distance.

Claims

1. A projection unit (7) for a field-of-view display device (1), the projection unit comprising: - A projector (8) for imaging, used to generate a projection beam (L) with the desired display content, and - A combination comprising a holographic diffuser (3) and a refractive element (11) extending on or behind the back side (3b) of the generated projection beam (L), wherein the projector (8), the holographic diffuser (3) and the refractive element (11) are configured and arranged to each other such that, - The generated projection beam (L) first enters the front side (3a) of the holographic diffuser (3) facing the projector (8) and is transmitted by the diffuser to the refractive element (11), and the projection beam is reflected back by the refractive element to the back side (3b) of the holographic diffuser (3). - Wherein, the holographic diffuser (3) is configured as a transmissive diffuser with predetermined direction selectivity and scattering characteristics for the projection beam incident from the back side, and the projection unit (7) is configured to project the resulting projection beam onto a transparent projection glass (4) to generate a virtual display image (V) in the user's field of vision. Backscattering caused by interference from external light reaching the projection unit is suppressed by the structure and orientation of the front side of the holographic diffuser and / or by the direction and / or wavelength selectivity of the holographic structure therein for light incident on the front side.

2. The projection unit (7) according to claim 1, wherein, The projection unit (7) is used in the transport vehicle (2).

3. The projection unit (7) according to claim 1, wherein, The refractive element (11) is a plane mirror.

4. The projection unit (7) according to claim 1, wherein, The user is the driver.

5. The projection unit (7) according to claim 1, wherein, The projector (8), the holographic diffuser (3), and the refractive element (11) are configured and arranged to each other such that, - The resulting projection beam (L) that is first incident on the front side (3a) of the holographic diffuser (3) facing the projector (8) is transmitted by the diffuser in the direction of the refractive element (11) without change and / or loss.

6. The projection unit (7) according to any one of claims 1 to 5, wherein, The projector (8), the holographic diffuser (3), and the refractive element (11) are configured and arranged to each other such that, - The holographic diffuser (3) produces a real image of the displayed content on the holographic diffuser for the projection beam that enters from the back side and exits from the front side.

7. The projection unit (7) according to any one of claims 1 to 5, wherein, The predetermined directional selectivity of the holographic diffuser (3) for the aforementioned projection beam (L) incident from the back side is designed to ensure the maximum and / or uniform projection light intensity in a predetermined beam cross section and / or the minimum and / or imperceptible projection light intensity outside the beam cross section, the beam cross section filling the eyebox (10) determined for the user's eye or the virtual display image (V) that can be generated.

8. The projection unit (7) according to any one of claims 1 to 5, wherein, The refractive element (11) extends behind the back side (3b) of the holographic diffuser (3) at a predetermined distance (D).

9. The projection unit (7) according to claim 8, wherein, The predetermined distance (D) is constant.

10. The projection unit (7) according to claim 8, wherein, The distance is from a few millimeters to a few centimeters.

11. The projection unit (7) according to any one of claims 1 to 5, wherein, The holographic structure of the holographic diffuser (3) is a volume hologram.

12. The projection unit (7) according to claim 11, wherein, The diffuser hologram of the holographic diffuser (3) is configured as a volume hologram.

13. The projection unit (7) according to any one of claims 1 to 5, wherein, The holographic diffuser (3) is configured as a sheet or film.

14. The projection unit (7) according to claim 13, wherein, The sheet or film is planar.

15. The projection unit (7) according to any one of claims 1 to 5, wherein, The projection unit has one or more additional optical elements in the optical path of the projection beam, following the holographic diffuser (3).

16. The projection unit (7) according to claim 15, wherein, The one or more additional optical elements are concave mirrors (9).

17. A field of view display device (1), the field of view display device comprising a projection unit (7) according to any one of claims 1 to 16 and a projection glass (4) disposed in the optical path of a projection beam output from the projection unit, which is reflective on the user side and transparent on the back side. - in, The projection unit (7) and the projection glass (4) are configured relative to each other such that the projection beam output by the projection unit (7) during operation is incident on the projection glass (4) and reflected by the projection glass to the user, thereby generating a virtual display image (V) behind the projection glass in the user's field of vision.

18. The field-of-view display device (1) according to claim 17, wherein, The field of view display device (1) is used in a vehicle (2).

19. The field-of-view display device (1) according to claim 17, wherein, The projection glass (4) is the windshield (5) of the vehicle (2).

20. The field-of-view display device (1) according to claim 17, wherein, The user is the driver of the transport vehicle (2).

21. Means of transport (2), including: - A windshield (5) and a dashboard (6), the upper side of which extends below the windshield (5), and - The field of view display device (1) according to any one of claims 17 to 20, wherein the projection glass (4) of the field of view display device is formed through the windshield (5) and the projection unit (7) of the field of view display device is disposed in the dashboard (6) for inserting a virtual display image (V) into the field of view of an occupant when the occupant looks through the windshield (5).

22. The means of transport (2) according to claim 21, wherein, The upper side of the instrument panel (6) has an opening aperture for the projection beam output by the projection unit (7).

23. The means of transport (2) according to claim 21 or 22, wherein, The means of transport (2) is a motor vehicle.

24. The means of transport (2) according to claim 21 or 22, wherein, The passenger in question is the driver.

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