Display device with a sequence of a plurality of floating real image surfaces for improving the optical quality

Abstract

The invention relates to a display device which is composed of a plurality of floating display modules, wherein: each individual module comprises an image-generating display, having a flat display surface, and a flat imaging optical unit which is provided at a specified axial distance therefrom, extends along the display surface, and is designed to image display content generated on the display surface onto a real image surface which is freely floating in the air and lies on the user-side of the imaging optical unit facing away from the display; and the individual display surfaces are arranged at such specified lateral distances to one another and at such specified setting angles with respect to one another that the associated floating real image surfaces seamlessly adjoin one another in each case, thereby resulting in an uninterrupted composite floating real image surface which is concave from the user's point of view.

Description

[0001] 24-0721

[0002] 1

[0003] Description

[0004] Display device with a series of several floating real image surfaces for optical quality improvement

[0005] The invention relates to a display device, which may be designed in particular for installation in a vehicle. The invention therefore also relates to a vehicle equipped with such a device, which may be a motor vehicle or another type of land, air, or water vehicle.

[0006] For example, WO 2017 / 155748 A2 describes floating displays based on microlens arrays (MLAs) or lens systems in the form of reconvergent films for generating a floating display in which a real image appears to hover in the air in front of the viewer. Lens systems of this type generate the floating real image with high efficiency and are independent of both wavelength and polarization. Furthermore, it is known, for example, from JP 2014-067071 A, to avoid touching a touchscreen with fingers, by means of an imaging device arranged above a display (for example, a lens or a multi-path mirror consisting of a planar arrangement of a large number of orthogonal mirror pairs) that generates a real display image floating in a defined spatial area above the imaging device.

[0007] However, this creates a problem: at wider viewing angles, there are significant limitations, such as double images or a deterioration in image quality and color performance. 24-0721

[0008] 2. To prevent this, the viewing angle range must be restricted, which is usually achieved by appropriately limiting the image size of the floating real image.

[0009] The object of the invention is to provide an alternative and / or improved display concept, particularly for vehicles, which can avoid such problems.

[0010] This problem is solved by a display device according to claim 1 and by a vehicle equipped therewith according to the dependent claim. Further embodiments are specified in the dependent claims. All further features and effects mentioned in the claims and in the following description for the display device also apply to the vehicle, and vice versa.

[0011] According to a first aspect, a display device is provided which can be designed, in particular, for installation in a vehicle. The vehicle can be a motor vehicle, but also any other land, air, or watercraft. When used in a vehicle, all spatial orientation terms used herein, such as "above," "below," "horizontal," "vertical," etc., refer, unless otherwise specified, to the usual vehicle-fixed Cartesian coordinate system with mutually perpendicular longitudinal, transverse, and vertical directions of the vehicle.

[0012] The display device consists of several floating display modules. Each of these modules comprises an image-generating display with a flat display surface and a flat imaging optic extending at a predetermined axial distance from the display surface. The terms "axial distance" and "lateral distance" used herein refer to 24-0721.

[0013] 3 an optical axis of the respective display module, which corresponds to a normal direction of its display surface.

[0014] The imaging optics are designed to project content generated on the display surface onto a real image surface that floats freely in the air and is located on the user-facing side of the imaging optics, away from the display. This floating real image surface can also be essentially flat and extend approximately parallel to the display surface. While a largely parallel alignment of all optically relevant surfaces within a module can be advantageous, for example, for its spatial compactness, ease of manufacture, and / or optical properties, curved surfaces and / or surfaces angled in a predetermined way relative to the display surface are also possible for the imaging optics and / or the floating real image surface. This allows for greater design freedom and the achievement of related additional effects.For similar reasons, the individual modules can, but do not all have to, be identically designed and dimensioned and / or angled identically to each other in pairs in order to achieve the effects described below.

[0015] The display surfaces of the individual modules are arranged at predetermined lateral distances and angles to each other such that the corresponding floating real image surfaces seamlessly connect to one another, resulting in an uninterrupted (i.e., without gaps or cracks) composite floating real image surface that appears concave from the user's perspective. In other words, the respective adjacent floating real image surfaces, which connect seamlessly along a straight line, meet at a predetermined angle of less than 180° from the user's perspective. This angle, which can be between approximately 150° and approximately 170°, is measured in a plane perpendicular to the aforementioned straight line and 24-0721

[0016] 4 generally corresponds (among other things, in the case of a parallel alignment of all optical surfaces within a module) to the aforementioned angle of inclination of the individual display surfaces (which, however, unlike their real images, which result in the floating real image surfaces, do not directly border each other, but have the aforementioned lateral distance to each other, which can be used, for example, for mounting, cooling, etc. of the individual modules).

[0017] The individual modules within the display device can be permanently connected to one another, for example, by means of fasteners designed to maintain the specified distances and angles of inclination. Examples include a rear mounting plate, a protective housing, or mounting strips positioned between each pair of modules, among others. Alternatively, the individual modules can be attached not directly to each other, but to a higher-level system, such as a vehicle in which the display device is installed, in the aforementioned arrangement.

[0018] One idea of ​​the display device proposed herein is to divide the imaging unit into individual modules (each designed for floating, real image generation) and to orient these modules at different angles so that the aforementioned limitations of the viewing angle range, known for prior art floating displays, are eliminated. This arrangement also offers the additional advantage that the transitions between the individual visible display planes are uninterrupted, since they float, even though the imaging unit itself has gaps between its individual modules. These gaps can be useful, for example, for mounting, insulating, and / or cooling the correspondingly larger imaging unit when the combined display area is enlarged. Furthermore, the proposed arrangement results in a real floating image. 24-0721

[0019] 5 with a depth effect (curvature) which provides additional benefits through the possibility of depth representation or better image perception for the viewer, for example in terms of ergonomics or image distance from his eyes.

[0020] In other words, the concave display surface (a composite, real, floating image surface) at least partially surrounds the area around its user, enabling a particularly natural and pleasant perception and thus an ergonomic effect of the displayed content. The depicted floating image is real; that is, it can be captured by light-sensitive material and made visible to everyone by a light-diffusing surface, if such a material or surface were placed at the image's position.

[0021] The aforementioned imaging optics, particularly through a suitable choice of its effective focal length, allow the real image to be generated at the most suitable and comfortable viewing distance from the user's eyes. This viewing distance can be significantly shorter, especially compared to a hard display surface or virtual image generation. It can be, for example, less than one meter or even less than half a meter. Such viewing distances are ideally suited (similar to a computer screen) for displaying and reading small print and / or high-resolution information.

[0022] In principle, any imaging technology is suitable for the respective display. It can be designed, in particular, to dynamically generate the required or desired display content in a two-dimensional pixel matrix. For example, it can be a light-transmitting or light-emitting flat panel display, such as a liquid crystal display (LCD) or a pLED or 24-0721.

[0023] 6

[0024] OLED display, but alternatively also designed as a projector-based image transmitter or a waveguide-based display.

[0025] According to one embodiment, the imaging optics of each module are designed such that a beam of light rays generated by its display surface, which carries the displayed content, reaches only an eyebox predetermined for the user's eyes (in particular, that of a single user); and the sizes and angles of the individual display surfaces are selected such that the maximum opening angle of the respective floating real image surface required to illuminate the entire eyebox is smaller than a predetermined maximum opening angle. The maximum required opening angle of the respective floating real image surface is defined as the largest angle measured at the edge of this image surface between its surface normal and a straight line connecting the same edge point of the image with the furthest edge point of the eyebox.

[0026] The eyebox, as is customary, is understood to be the area of ​​space from which the displayed, floating real-world image is fully visible. In other words, the beam of light is essentially confined to this area. The eyebox can be dimensioned accordingly for use by a single person. For example, in a vehicle application, the eyebox can be limited to the width and height of the user's seat or headrest, ensuring that no other people nearby can see the floating real-world image. This allows the user to view confidential content ("privacy"). At the same time, it prevents other people in the user's vicinity, such as other vehicle occupants or bystanders, from being visually disturbed by the display, as they cannot see it.Furthermore, by spatially limiting the light beam to a single-user eyebox, the light energy required for its generation can be saved. 24-0721.

[0027] 7

[0028] In this embodiment, the predetermined maximum opening angle can be, for example, less than 45°, less than 35°, or even less than 25°. For this purpose, three to five appropriately small individual modules, arranged in a horizontal direction and at an angle to one another as described herein, can suffice to cover a large horizontal field of view of, for example, more than 40°, 60°, or 80° with high image quality (i.e., in particular, without double images and / or with largely consistent sharpness, scaling, color performance, homogeneity, and / or brightness). The same can, of course, also be provided in the vertical direction to extend the user's field of view, which can be covered by the assembled floating real image, vertically as well, while maintaining consistently high image quality.

[0029] Alternatively or additionally to the above embodiment, the angles of inclination of the individual display surfaces can be dimensioned such that their corresponding floating real image surfaces have a substantially equal image distance from the aforementioned eyebox, defined as the distance from the center of the respective floating real image surface to the center of the eyebox. This can lead to increased comfort, particularly with an eyebox designed for a single user, as the combined, and therefore potentially arbitrarily large, floating real display surface maintains a largely constant image distance from the user's eyes across its entire display area. This can be especially ergonomic for reading, working, or gaming, for example, and thus allow the user to use the device for extended periods without fatigue.

[0030] The imaging optics of each module may, for example, comprise a microlens array (MLA) or an arrangement of two or more microlens arrays arranged successively in the beam path, which is used to image the display area or the display content generated therein onto the 24-0721

[0031] The image surface is formed by eight associated, freely suspended real image areas. The number of microlens arrays and their lens or surface geometry can be selected differently depending on the requirements of a specific application in order to enable different aperture angles and imaging properties (such as magnification, image distance, etc.). Alternatively or additionally, the imaging optics can also include one or more other types of imaging and / or deflecting optical elements for the same purpose, such as a (for example, plane-parallel) film or plate structured with mirrors, prisms, or other refractive and / or reflective microstructures.

[0032] Due to the overall flat design of the training optics, the respective module can have a total thickness of less than 5 cm, for example of about 3 to 4 cm, about 3 to 3.5 cm or even less, which can further facilitate its integration in a vehicle where the installation space is typically limited.

[0033] The two or more microlens arrays arranged successively in the beam path can be mirror-symmetrical to each other in the beam propagation direction. This allows for particularly good optical functionality, especially very high image quality for the floating real image.

[0034] Optionally, each module can include a cover plate or layer located on the user-side of the imaging optics, forming a user-side module surface and designed to transmit the beam of light generated by its display area. In this case, the floating real image area of ​​the respective module lies in the air between its cover plate or layer and an eyebox predetermined for the user's eyes. 24-0721

[0035] 9

[0036] The cover plate / layer can be made of any material transparent to the display light, such as plastic or glass. It, and in particular its user-facing surface, can be planar (i.e., flat). However, the cover plate / layer can also have a freeform surface on one or both sides to create a predetermined optical effect and / or a predefined geometry, for example, of a vehicle component. Finally, the cover plate / layer can also provide mechanical protection for the module's optical components, especially its imaging optics. In the version with MLAs, the cover plate can be formed on a user-facing surface of the last microlens array in the beam path. Alternatively, the cover plate can be separate from the microlens array.the arrangement of the microlens arrays is provided for, which means additional design freedom for both the last microlens array in the beam path and for the cover plate itself.

[0037] To significantly impede or even almost completely prevent the user and others from seeing inside the module through the cover plate or layer, the cover plate or layer can be at least partially opaque to ambient light. This can be achieved, for example, by incorporating a perforated film, adding particles, coloring, tinting, a polarizing filter, and / or an LC layer that can be switched uniformly (i.e., as a whole) or segmentally. In particular, the cover plate or layer can have a higher transmittance for the outward-exiting display light than for the incoming ambient light, for example, through light-blocking layers / structures on one side or suitable polarizing filters, possibly in combination with appropriately polarized display light. 24-0721

[0038] 10

[0039] This reduction in transparency allows the cover plate / layer to be darkened to such an extent that it forms a dark or even black background for a particularly high-contrast display of the floating real-world image. In other words, the cover plate / layer, through its targeted darkening, can serve as a contrast medium for displaying the floating real-world image with the desired contrast. Since ambient light, unlike the display light, must pass through the cover plate / layer twice to illuminate the interior of the respective module when viewed from the outside, this ambient light can be attenuated at least twice as much as the display light by light-absorbing particles, perforations, or a suitable polarizing filter in the cover plate / layer.For example, a perforated film with a transmission rate of about 40% can ensure perfect visibility of the floating real image for the user because it allows less than 16% of the disturbing ambient light to pass through and therefore forms an almost black image background.

[0040] According to a further aspect, the above-mentioned vehicle, in particular a motor vehicle, is intended. The vehicle comprises a passenger compartment and one or more display devices of the type presented herein, each designed to generate a real image suspended in the air either in the passenger compartment or on the exterior of the vehicle, and for this purpose arranged accordingly in the passenger compartment or in an exterior vehicle element. The display devices can, for example, be integrated into an instrument panel, armrests, A-, B-, C-, or D-pillars, vehicle doors, and / or tailgates.

[0041] The above aspects of the invention, its embodiments, and specific configurations are explained in more detail below with reference to an example illustrated in the accompanying drawing. Drawing 24-0721

[0042] Figure 11 is to be understood as a purely schematic illustration of the basic structural and functional principle, that is, not to scale. It shows:

[0043] Figure 1 shows a cross-sectional view of the basic structure of a display device according to an embodiment of the invention.

[0044] All the various embodiments, alternatives, and specific features of the display device and the vehicle mentioned above in the description and in the subsequent claims, according to the aspects of the invention described above, can be implemented in the example shown in Figure 1, particularly as alternatives or additional features to those shown therein. Therefore, they are not all repeated below. The same applies accordingly to the definitions and effects of terms already given above with regard to individual features shown in Figure 1.

[0045] Fig. 1 shows a highly simplified schematic cross-sectional view (here, purely by way of example, a horizontal longitudinal section) of a display device 1 according to an embodiment of the invention. In this example, the display device 1 is designed for individual use by a single user 2. For the user to see its display in the intended display quality, their eyes must be located within a predetermined spatial area (eyebox E). The display device 1 can, for example, be integrated as an interior or exterior display in a vehicle (not shown), in particular a motor vehicle. As already mentioned, in this case, the spatial orientation terms such as "up," "down," "left," "right," "horizontal," "vertical," etc., refer to the usual vehicle-mounted Cartesian coordinate system with mutually perpendicular longitudinal, transverse, and vertical directions of the vehicle. 24-0721

[0046] 12

[0047] The display device 1 in Fig. 1 is composed, purely by way of example, of three individual floating display modules 3, which are identical in design and dimensions. However, two, four, five, or more individual modules 3 of this type can also be provided in the display device 1 according to the same arrangement principle. Each module 3 comprises an image-generating display 4 with a flat display surface 5 and a flat imaging optic 6, which in this example is designed as a microlens array (MLA) and extends at a predetermined constant axial distance from the display surface 5. The terms "axial distance" and "lateral distance" refer to an optical axis of the respective display module 3, which corresponds to a normal direction N of its display surface 5.

[0048] The imaging optics 6 are designed to project the entire display area 5, or any display content generated on the display area 5, onto a real image surface 7 that floats freely in the air and is located on the user-facing side of the imaging optics 6, away from the display 4. In this example, the respective floating real image surface 7 is also planar and extends approximately parallel to the corresponding display area 5, so that their normal directions N also coincide approximately.

[0049] The display surfaces 5 of the individual modules 3 are arranged at predetermined lateral (i.e., side) distances from one another and at predetermined angles to one another such that the corresponding floating real image surfaces 7 seamlessly connect to one another, thereby forming an uninterrupted composite floating real image surface R, which is concave from the user's perspective 2. In other words, the respective adjacent floating real image surfaces 7, which seamlessly connect to one another along a straight line, meet at a predetermined angle of less than 180° from the user's perspective. This angle, which can be approximately 150°, 160°, or 170°, for example, is specified in a diagram relating to 24-0721.

[0050] The perpendicular plane mentioned in 13 (which corresponds to the drawing plane of Fig. 1) is measured and in this example also corresponds to the mentioned angle of inclination of the individual display surfaces 5 (which, however, unlike their real representations, i.e. the floating real image surfaces 7, do not directly border each other, but have the lateral distance to each other clearly recognizable in Fig. 1, which can be used, for example, for fastening, cooling, etc. of the individual modules 3).

[0051] This arrangement ensures that the maximum opening angle β or y required to illuminate the entire eyebox E of the respective floating real image surface 7 is smaller than a predetermined maximum opening angle at which the respective floating real image surface 7 is visible from the entire eyebox E with the intended optical quality. As illustrated in Fig. 1, the maximum required opening angle β or y of the respective floating real image surface 7 is defined as the largest angle measured at the edge of the respective image surface 7 between its surface normal N and a light ray L connecting the same edge point of the image with the furthest edge point of the eyebox.

[0052] If, instead, a display area of ​​the same size as in Fig. 1 were created with a single module 3, i.e. with a flat display area 5 three times as large, the aforementioned maximum required opening angle would also be correspondingly larger, which would lead to significant losses in quality such as double images, reduced brightness, deteriorated color representation, inhomogeneities, etc., especially in the edge areas of the display area or in the edge areas of the eyebox E.

[0053] As a positive additional effect of the angled arrangement of the individual modules 3 to each other presented here, the concave display surface (that is, the composite real floating image surface R) partially surrounds a 24-0721

[0054] 14

[0055] The spatial area around the user 2 allows for a particularly natural and pleasant perception and thus an ergonomic effect of the display content shown in this composite display surface. Furthermore, with a seamless, floating display surface R, the lateral gaps between the individual modules 3 that are still possible are extremely useful for their mounting, cooling, etc.

[0056] 24-0721

[0057] 15

[0058] Reference symbol list

[0059] 1 Display device 2 Users

[0060] 3 individual floating display module 4 image-generating display

[0061] 5 Display area 6 Image optics

[0062] 7 floating real image surface of a module L light beam

[0063] R continuously composite floating real image area E Eyebox N Normal direction

Claims

24-0721 16 Claims 1. Display device (1) comprising several floating display modules (3), wherein: each individual module (3) comprises an image-generating display (4) with a flat display surface (5) and a flat imaging optic (6) arranged at a predetermined axial distance therefrom, extending along the display surface (5) and designed to project a display content generated in the display surface (5) onto a real image surface (7) floating freely in the air, located on a user-side side of the imaging optic (6) facing away from the display (4); and the individual display surfaces (5) are arranged at predetermined lateral distances from one another and at predetermined angles to one another such that the associated floating real image surfaces (7) each seamlessly connect to one another, thereby forming an uninterrupted composite floating real image surface (R) which is concave from the user's perspective.

2. Display device (1) according to claim 1, wherein the imaging optics (6) of each module (3) are designed such that a beam of light rays generated by its display surface (5) with the display content reaches only an eyebox (E) predetermined for user eyes; and the sizes and angles of inclination of the individual display surfaces (5) are dimensioned such that a maximum opening angle of the respective floating real image surface (7) required to illuminate the entire eyebox (E), defined as the largest at 24-0721 17 The angles measured at the edge of this image area (7) between its surface normal (N) and a light ray (L) connecting the same image edge point with a furthest eyebox edge point are smaller than a predetermined maximum opening angle.

3. Display device (1) according to claim 2, wherein the predetermined maximum opening angle is less than 45°, preferably less than 35°, particularly preferably less than 25°.

4. Display device (1) according to one of the preceding claims, wherein the imaging optics (6) of each module (3) is designed such that a beam of light rays generated by its display surface (5) with the display content reaches only an eyebox (E) predetermined for user eyes; and the angles of inclination of the individual display surfaces (5) are dimensioned such that their associated floating real image surfaces (7) have a substantially equal image distance from the eyebox (E), which is defined as a distance from a center of the respective floating real image surface (7) to an eyebox center.

5. Display device (1) according to one of the preceding claims, wherein the imaging optics (6) of each module (6) comprises a microlens array or an arrangement of two or more successive microlens arrays in the beam path, which(s) are used to image the display area (5) or 24-0721 18 of the display content generated therein is / are formed on the associated real image surface (7) which is freely suspended in the air.

6. Display device (1) according to claim 5, wherein the two or more successive microlens arrays in the beam path are arranged and designed in a mirror-symmetrical manner relative to each other in the direction of beam propagation.

7. Display device (1) according to one of the preceding claims, wherein the imaging optics (6) of each module (3) comprises a film or plate structured with mirrors, prisms or other refractive and / or reflective microstructures, which is / are designed to image the display surface (5) or the display content generated therein onto the associated real image surface (7) floating freely in the air.

8. Display device (1) according to one of the preceding claims, wherein each module (3) further comprises a cover plate or layer arranged on the user-side side of the imaging optics (6), which forms a user-side module surface and is designed to allow the light beam generated by its display (4) to pass through with the display content; and the floating real image area (7) of the respective module (3) lies in the air between its cover plate or layer and an eyebox (E) predetermined for user eyes.

9. Display device (1) according to claim 8, wherein 24-0721 19 the cover plate or layer is made opaque to ambient light incident on it from the outside by a perforated film, a particle addition, coloring, tinting, a polarizing filter and / or a segmentally or uniformly switchable LC layer to such an extent that it substantially prevents the view into the interior of the module (3).

10. Vehicle, in particular a motor vehicle, comprising: a passenger compartment; and at least one display device (1) according to one of the preceding claims, each designed to generate a real image suspended in the air in the passenger compartment or on the outside of the vehicle and is accordingly integrated in the passenger compartment or in an external vehicle element.

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